ORNL
Oak Ridge
National
Laboratory
Operated by
Union Carbide Corporation for the
Department of Energy
Oak Ridge, Tennessee 37830
ORNL/EIS-128
EPA
United States
Environmental Protection
Agency
Office of Research and Development
Health Effects Research Laboratory
Cincinnati, Ohio 45268
EPA-600/1-79-012
REVIEWS OF THE ENVIRONMENTAL
EFFECTS OF POLLUTANTS:
XI. Chlorophenols
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL HEALTH EFFECTS RE-
SEARCH series. This series describes projects and studies relating to the toler-
ances of man for unhealthful substances or conditions. This work is generally
assessed from a medical viewpoint, including physiological or psychological
studies. In addition to toxicology and other medical specialities, study areas in-
clude biomedical instrumentation and health research techniques utilizing ani-
mals — but always with intended application to human health measures.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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ORNL/EIS-128
EPA-600/1-79-012
REVIEWS OF THE ENVIRONMENTAL EFFECTS OF POLLUTANTS: XI. CHLOROPHENOLS
Report prepared by
Van P. Kozak, Geronimo V. Simsiman, Gordon Chesters, David Stensby,
and John Harkin
Water Resources Center
University of Wisconsin
Madison, Wisconsin 53706
under Subcontract No. 7028 for
Information Center Complex
Information Division
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee 37830
operated by
UNION CARBIDE CORPORATION
for the
DEPARTMENT OF ENERGY
Contract No. W-7405-eng-26
Reviewer and Assessment Chapter Author
Gary A. Van Gelder
University of Missouri
Columbia, Missouri 65201
Interagency Agreement No. D5-0403
Project Officer
Jerry F. Stara
Office of Program Operations
Health Effects Research Laboratory
Cincinnati, Ohio 45268
Date Published: June 1979
Prepared for
HEALTH EFFECTS RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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This report was prepared as an account of work sponsored by an agency
of the United States Government. Neither the United States Government nor
any agency thereof, nor any of their employees, contractors, subcontractors,
or their employees, makes any warranty, express or implied, nor assumes any
legal liability or responsibility for any third party's use or the results
of such use of any information, apparatus, product or process disclosed in
this report, nor represents that its use by such third party would not
infringe privately owned rights.
This report has been reviewed by the Health Effects Research Laboratory,
U.S. Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and policies
of the U.S. Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation for use.
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CONTENTS
Tables
Part A — Summary of Comparative Relationships of Chlorophenols .
A. 2.1 Physical Properties
A. 2. 3 Uses
A. 2. 4 Chemical Reactivity
A. 2. 5 Transport and Transformation in the Environment. .
A. 3 Biological Aspects in Microorganisms
A. 3.1 Bacteria
A. 3. 1.1 Metabolism
A. 3. 1.2 Effects
A. 3. 2 Fungi
A. 3. 2.1 Metabolism
A. 3. 2. 2 Effects
A. 3. 3.1 Metabolism
A. 3. 3. 2 Effects
A. 4. 1.2 Transport and Distribution
A. 4. 1.3 Biotransformation
A. 4. 1.4 Elimination
A. 4. 2 Effects
A. 4. 2.1 Physiological or Biochemical Role ....
A. 4. 2. 2 Toxicity
A. 5 Biological Aspects in Wild and Domestic Animals
A.ST1 THnlogiral Aspects in Birds AnH MAnpnal s
A. 5. 1.1 Metabolism
A. 5. 1.2 Effects
A. 5. 2 Biological Aspects in Fish and Other Aquatic
A. 5. 2.1 Metabolism
A. 5. 2. 2 Effects
A. 6 Biological Aspects in Humans
A. 6.1 Metabolism
A. 6. 1.2 Transport and Distribution
A. 6. 1.3 Biotransformation
A. 6. 1.4 Elimination
XV
1
3
4
4
4
4
7
7
7
9
9
9
10
12
12
13
13
13
13
18
18
18
18
19
19
20
20
20
24
24
24
25
26
26
27
33
33
33
33
35
36
iii
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IV
A.6.2 Effects 38
A.6.2.1 Physiological or Biochemical Role 38
A. 6.2.2 Toxicity 38
A.6.2.3 Carcinogenicity 45
A. 6.2.4 Teratogenicity 45
A. 6.2.5 Mutagenicity 45
A.6.2.6 Aplastic Anemia 46
A.7 Environmental Distribution and Transformation 49
A. 7.1 Trends in Production and Use 49
A. 7.2 Sources of Pollution 49
A. 7.3 Environmental Fate 51
A. 7.3.1 Mobility and Persistence in Air 51
A.7.3.2 Mobility and Persistence in Aquatic
Environments 51
A. 7.3.3 Mobility and Persistence in Soil 53
A. 7.4 Waste Management 54
A.8 Environmental Interactions and Their Consequences 57
A.8.1 Environmental Cycling of Chlorophenols 57
A.8.2 Chlorophenols in Food 59
Part B — 2-Chlorophenol and 2,4-Dichlorophenol 63
B.I Summary 65
B.I.I Discussion of Findings 65
B.I. 2 Conclusions 70
B.2 Chemical and Physical Properties and Analysis 72
B.2.1 Physical Properties 72
B.2.2 Manufacture 72
B.2.3 Uses 73
B.2.4 Chemical Reactivity 73
B.2.5 Transport and Transformation in the Environment. . . 74
B.2.5.1 Air 74
B.2.5.2 Aquatic Environment 74
B.2.5.3 Soils 75
B.2.6 Analysis 75
B.2.6.1 Sampling, Storage, and Preservation .... 76
B.2.6.2 Sample Preparation for Analysis 76
B.2.6.3 Determination and Identification 77
B.2.6.4 Assessment of Methods 82
B.3 Biological Aspects in Microorganisms 87
B.3.1 Bacteria 87
B.3.1.1 Metabolism 87
B.3.1.2 Effects 87
B.3.2 Fungi 89
B.3.2.1 Metabolism 89
B.3.2.2 Effects 90
B.3.3 Algae 91
B.3.3.1 Metabolism 91
B.3.3.2 Effects 91
B.4 Biological Aspects in Plants 94
B.4.1 Metabolism 94
B.4.1.1 Uptake and Absorption 94
B.4.1.2 Transport and Distribution 97
B.4.1.3 Biotransformation 98
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B.5
B.6
B.7
i.
V
B.8
Part C
C.I
C.2
B.4.1.4 Elimination
B.4.2 Effects
B.4.2.1 Physiological or Biochemical Role
B.4.2.2 Toxicity
Biological Aspects in Wild and Domestic Animals
B.5.1 Biological Aspects in Birds and Mammals
B.5. 1.1 Metabolism
B.5. 1.2 Effects
B.5. 2 Biological Aspects in Fish and Other Aquatic
Organisms
B.5. 2.1 Metabolism
B.5. 2. 2 Effects
B.6.1 Metabolism
B.6. 1.3 Biotransformation
B.6. 1.4 Elimination
B.6. 2 Effects
B.6. 2.1 Physiological or Biochemical Role
B.6. 2. 2 Toxicity
Environmental Distribution and Transformation
B.7.1 Trends in Production and Use
B.7. 2 Sources of Pollution
B.7. 2.1 Distribution in Air
B.7. 2. 2 Distribution in Aquatic Environments. . . .
B.7. 2. 3 Distribution in Soil
B.7. 3 Environmental Fate
B.7. 3.1 Mobility and Persistence in Air
B.7. 3. 2 Mobility and Persistence in Aquatic
Environments
B.7. 3. 3 Mobility and Persistence in Soil
B.7. 3. 4 Microbial Decomposition in Soils and
Aquatic Environments
B.7. 3. 5 Photodecomposition
B.7. 4 .waste Management
— B . 7 . 4 . 1 Primary Treatment
B.7. 4. 3 Soil Disposal
B.7. 4. 4 Chemical Oxidation
B.7. 4. 5 Ion Exchange
Environmental Interactions and Their Consequences ......
B.8.1 Environmental Cycling of 2-Chlorophenol and
B.8. 2 2-Chlorophenol and 2,4-Dichlorophenol in Food. . . .
— 2,4,5-Trichlorophenol, 2,4,6-Trichlorophenol, and
C.I. 2 Conclusions
Chemical and Physical Properties and Analysis
99
100
100
100
107
107
107
110
110
110
110
114
114
114
114
114
115
117
117
117
124
124
125
125
125
127
127
127
128
131
134
137
139
139
139
140
140
141
141
146
146
147
149
151
151
157
160
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vi
C.2.1 Physical Properties 160
C.2.2 Manufacture 160
C.2.3 Uses 160
C.2.4 Chemical Reactivity 161
C.2.5 Transport and Transformation in the Environment. . . 162
C.2.5.1 Air 162
C.2.5.2 Aquatic Environment 162
C.2.5.3 Soils 163
C.2.6 Analysis 163
C.2.6.1 Sampling, Storage, and Preservation .... 163
C.2.6.2 Sample Preparation for Analysis 163
C.2.6.3 Determination and Identification 163
C.3 Biological Aspects in Microorganisms 172
C.3.1 Bacteria 172
C.3.1.1 Metabolism 172
C.3.1.2 Effects 172
C.3.2 Fungi 175
C.3.2.1 Metabolism 175
C.3.2.2 Effects 175
C.3.3 Algae 179
C.3.3.1 Metabolism 179
C.3.3.2 Effects 179
C.4 Biological Aspects in Plants 182
C.4.1 Metabolism 182
C.4.1.1 Uptake and Absorption 182
C.4.1.2 Transport and Distribution 182
C.4.1.3 Biotransfonnation 182
C.4.1.4 Elimination 183
C.4.2 Effects 183
C.4.2.1 Physiological or Biochemical Role 183
C.4.2.2 Toxicity 183
C.5 Biological Aspects in Wild and Domestic Animals 186
C.5.1 Biological Aspects in Birds and Mammals. ...... 186
C.5.1.1 Metabolism 186
C.5.1.2 Effects 188
C.5.2 Biological Aspects in Fish and Other Aquatic
Organisms 190
C.5.2.1 Metabolism 190
C.5.2.2 Effects 190
C.6 Biological Aspects in Humans 194
C.6.1 Metabolism 194
C.6.1.1 Uptake and Absorption 194
C.6.1.2 Transport and Distribution 197
C.6.1.3 Biotransfonnation 198
C.6.1.4 Elimination 199
C.6.2 Effects 200
C.6.2.1 Physiological or Biochemical Role 200
C.6.2.2 Toxicity 200
C.7 Environmental Distribution and Transformation 208
C.7.1 Trends in Production and Use 208
C.7.2 Sources of Pollution 209
C.7.2.1 Distribution in Air 209
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vii
C.8
Part D
D.I
D.2
D.3
D.4
C.7.2.2 Distribution in Aquatic Environments. . . .
C.7.2.3 Distribution in Soil
C . 7 . 3 Environmental Fate
C.7.3.1 Mobility and Persistence in Air
C.7.3.2 Mobility and Persistence in Aquatic
Environments
C.7.3.3 Mobility and Persistence in Soil
C.7.3.4 Microbial Decomposition in Soils and
Aquatic Environments
C.7.3.6 Pyrolysis
C.7.4.1 Primary Treatment
C.7.4.2 Secondary Treatment
C.7.4.3 Soil Disposal
C.7.4.4 Chemical Oxidation
C.7.4.5 Ion Exchange
C.7.4.6 Activated Carbon Adsorption
Environmental Interactions and Their Consequences
C.8.1 Environmental Cycling of Trichlorophenols and
Tetrachlorophenols
C.8. 2 Trichlorophenols and Tetrachlorophenols in Food. . .
Summary
D.I.I Discussion of Findings -.
D.I. 2 Conclusions
D.2.1 Physical Properties
D.2. 2 Manufacture
D.2. 3 Uses
D.2. 4 Chemical Reactivity
D.2. 5 Transport and Transformation in the Environment. . .
D.2. 5.1 Air
D . 2 . 5 . 2 Aquatic Environment
D.2. 5. 3 Soils
D.2. 6 Analytical Methods
Biological Aspects in Microorganisms
D.3.1 Bacteria
D.3. 1.1 Metabolism
D.3. 1.2 Effects :
D.3. 2 Fungi
D.3. 2.1 Metabolism
D.3. 2. 2 Effects
D.3. 3 Algae
D.3. 3.1 Metabolism
D.3. 3. 2 Effects
Biological Aspects in Plants
D.4.1 Metabolism
D.4. 2 Effects
D.4. 2.1 Physiological or Biochemical Role
D.4. 2. 2 Toxicity
209
210
210
210
210
211
213
216
218
218
219
219
219
219
220
220
225
225
226
229
231
231
243
246
246
246
246
246
247
247
247
248
250
260
260
260
261
263
263
264
264
264
264
272
272
274
274
275
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Vlll
D.5 Biological Aspects in Wild and Domestic Animals 282
D.5.1 Biological Aspects in Birds and Mammals 282
D.5.1.1 Metabolism 282
D.5.1.2 Effects 286
D.5.2 Biological Aspects in Fish and Other Aquatic
Organisms 297
D.5.2.1 Metabolism 297
D.5.2.2 Effects 312
D.6 Biological Aspects in Humans 333
D.6.1 Metabolism 333
D.6.1.1 Uptake and Absorption 333
D.6.1.2 Transport and Distribution 344
D.6.1.3 Biotransformation 357
D.6.1.4 Elimination 367
D.6.2 Effects 373
D.6.2.1 Physiological or Biochemical Role 373
D..6.2.2 Toxicity 373
D.6.2.3 Carcinogenicity 409
D.6.2.4 Teratogenicity 409
D.6.2.5 Mutagenicity 409
D.7 Environmental Distribution and Transformation 419
D.7.1 Trends in Production and Use 419
D.7.2 Sources of Pollution 419
D.7.2.1 Distribution in Air 419
D.7.2.2 Distribution in Aquatic Environments. . . . 423
D.7.2.3 Distribution in Soil 425
D.7.3 Environmental Fate 426
D.7.3.1 Mobility and Persistence in Air 427
D.7.3.2 Mobility and Persistence in Aquatic
Environments 427
D.7.3.3 Mobility and Persistence in Soil 428
D.7.3.4 Mobility and Persistence in Treated Wood. . 431
D.7.3.5 Microbial Decomposition in Soils and
Water 435
D.7.3.6 Photodecomposition 439
D.7.4 Waste Management 442
D.7.4.1 Primary Treatment 442
D.7.4.2 Secondary Treatment 442
D.7.4.3 Chemical Oxidation 443
D.7.4.4 Activated Carbon Adsorption 444
D.8 Environmental Interactions and Their Consequences 450
D.8.1 Environmental Cycling of Pentachlorophenol 450
D.8.2 Human Exposure 450
D.8.3 Biomagnification in Food Chains 451
D.8.3.1 Terrestrial Ecosystems 452
D.8.3.2 Aquatic Ecosystems 452
Part E — Environmental Assessment of Chlorophenols 455
E.I Introduction 457
E.2 Monochlorophenols and Dichlorophenols 457
E.2.1 Production, Uses, and Potential Environmental
Contamination 457
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E.2.1.1 Production 457
E.2.1.2 Uses 458
E.2.1.3 Losses to the Environment 458
E.2.2 Environmental Persistence 458
E.2.2.1 Physical and Chemical Properties 458
E.2.2.2 Analytical Methods 459
E.2.2. 3 Biological Degradation 460
E.2.3 Effects on Lower Life Forms 461
E.2.3.1 Effects on Bacteria, Fungi, and Algae . . . 461
E.2.3.2 Effects on Plants 461
E.2.4 Effects on Animals 462
E.2.4.1 Effects on Fish and Other Aquatic
Organisms 462
E.2.4.2 Effects on Birds, Wildlife, and Domestic
Animals 462
E.2.4.3 Effects on Laboratory Animals 463
E.2.5 Effects on Humans 463
E.2.6 Teratogenicity, Mutagenicity, and Carcinogenicity. . 463
E.2.7 Residues in Food and Water 464
E.3 Trichlorophenols and Tetrachlorophenols 464
E.3.1 Production, Uses, and Environmental Contamination. . 464
E.3.1.1 Production 464
E.3.1.2 Uses 465
E.3.1.3 Environmental Residues 465
E.3.2 Environmental Persistence 466
E.3.2.1 Chemical and Physical Properties 466
E.3.2.2 Analytical Methods 466
E.3.2.3 Biological Degradation 466
E.3.3 Effects on Lower Life Forms 467
E.3.3.1 Effects on Bacteria, Fungi, and Algae . . . 467
E.3.3.2 Effects on Plants 468
E.3.4 Effects on Animals 468
E.3.4.1 Effects on Aquatic Organisms 468
E.3.4.2 Effects on Birds 468
E.3.4.3 Effects on Mammals 468
E.3.5 Effects on Humans 469
E.3.6 Carcinogenicity and Teratogenicity 470
E.3.7 Standards and Regulations 470
E.4 Pentachlorophenol 470
E.4.1 Production, Uses, and Potential Environmental
Contamination 470
E.4.1.1 Production 470
E.4.1.2 Uses 470
E.4.1.3 Losses to the Environment 471
E.4.1.4 Environmental Residues 471
E.4.2 Environmental Persistence. ..... 472
E.4.2.1 Physical and Chemical Properties 472
E.4.2.2 Analytical Methods 473
E.4.2.3 Biological Degradation 473
E.4.3 Effects on Lower Life Forms 474
E.4.3.1 Effects on Bacteria, Fungi, and Algae ... 474
E.4.3.2 Effects on Plants 474
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E.4.4 Effects on Animals 475
E.4.4.1 Effects on Fish 475
E.4.4.2 Effects on Birds 475
E.4.4.3 Effects on Mammals 476
E.4.5 Effects on Humans 479
E.4.5.1 Exposure Factors 479
E.4.5.2 Toxicity 481
E.4.6 Teratogenic and Carcinogenic Effects 482
E.4.7 Standards and Regulations 482
E.4.8 Recommendations. 482
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FIGURES
A.4.1 Relationship between the logarithms of the solubilities
of chlorophenols and the logarithms of the LDSO in
Lerma minor 21
A.8.1 Possible cycling of chlorophenols in the environment .... 58
A.8.2 Proposed metabolic pathway for lindane in rats 60
B.7.1 Removal of 2,4-dichlorophenol and 2,4-D from solution in
aeration basin effluent by continuous aeration 130
B.7.2 Proposed pathway of 2-chlorophenol degradation by
Pseudomonas sp 135
B.7.3 Pathway for degradation of 2,4-dichlorophenol and
chlorocatechol by Arthrobacter sp 136
B.7.4 Photolysis pathway for 2,4-D . 138
C.5.1 Conversion of 2,3,4,6-tetrachlorophenol to 2,3,4,6-
tetrachloroanisole in simulated broiler house litter . . . 189
C.7.1 Removal of 2,4,5-trichlorophenol and 2,4,5-T from solution
in aeration basin effluent with continuous aeration. . . . 212
C.7.2 Removal of 2,4,6-trichlorophenol and 2,4,6-T from solution
in aeration basin effluent with continuous aeration. . . . 212
C.7.3 Degradation of tetrachlorophenol isomers in paddy soil . . . 214
C.7.4 Changes in amounts of pentachlorophenol degradation
products during incubation under flooded and upland
conditions 214
C.7.5 Proposed photodecomposition pathway for 2,4,5-T in aqueous
solution «.f_ . 217
>./>
C.7.6 Reaction scheme for the chlorination of phenol 220
D.2.1 Effect of pH on the adsorption of pentachlorophenol by
isolated allophanes 251
D.3.1 Probable detoxification of pentachlorophenol by the laccase
of Coriolus versicolor 265
D.4.1 Schematic illustration of the inhibition of phytate
decomposition by pentachlorophenol in germinating rice
seeds 276
xi
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Xll
D.5.1 Decrease of pentachlorophenol concentration in water
during culture of rainbow trout 298
D.5.2 Accumulation of pentachlorophenol in goldfish surviving in
pentachlorophenol media (0.1, 0.2, and 0.4 mg/liter) . . . 299
D.5.3 Pentachlorophenol levels in various tissues of eels from
seawater and freshwater tests 301
D.5.A Change with time of culture in amounts of free and bound
pentachlorophenol in the medium and of pentachlorophenol
in Tapes philippincantm from the medium 306
D.5.5 Change in amounts of pentachlorophenol in goldfish and in
free and bound pentachlorophenol in pentachlorophenol-
free water 307
D.5.6 Relative detoxification capacities of key organisms in a
model aquatic ecosystem following treatment with radio-
active pentachlorophenol 310
D.5.7 Retention of pentachlorophenol in goldfish during culture
in running water after a 24-hr exposure to pentachloro-
phenol media (0.1 and 0.2 mg/liter) 311
D.5.8 Retention of pentachlorophenol in goldfish during culture
in running water after various exposures (6 to 48 hr)
to 0.2 mg/liter pentachlorophenol 311
D.5.9 Boundary of lethal area for a variety of fish species,
relating lethal concentration of sodium pentachloro-
phenate to time of survival 315
D.5.10 Action of pentachlorophenol on eels in vivo 321
D.6.1 Pentachlorophenol in urine of two subjects following
respiratory exposure 336
D.6.2 Pentachlorophenol in paired blood and urine samples of
wood treaters and nonoccupationally exposed people .... 337
D.6.3 Pentachlorophenol in blood of rabbits after a single
oral dose of sodium pentachlorophenate 339
D.6.4 Pentachlorophenol in blood and urine of rabbits exposed
to a single oral dose 340
D.6.5 Pentachlorophenol remaining in two human subjects after
inhalation exposure 347
D.6.6 Relationship between pentachlorophenol concentrations in
plasma and urine 348
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xiii
D.6.7 Tissue distribution of [1AC]pentachlorophenol and/or
its labeled metabolites 40 hr after oral administration
to rats 354
D.6.8 Turnover of pentachlorophenol and/or its metabolites in
the mouse 355
D.6.9 Proposed turnover of pentachlorophenol and/or its
metabolites in mammals 356
D.6.10 [ 1
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TABLES
A. 2.1 Physical properties of chlorophenols 5
A.2.2 Synthesis, uses, and reactions of chlorophenols 6
A.3.1 Antibacterial efficiencies of the higher chlorophenols ... 11
A.3.2 Bactericidal activities of halogenated phenols 12
A. 3.3 Antifungal efficiencies of chlorophenols 14
A.3.4 Effect of chlorophenols on chlorophyll synthesis by
Chlofella pyreno-idosa 15
A.3.5 Toxicity constants of chlorophenols to Chlorella
pyveno-idosa 16
A.4.1 Concentration of chlorophenols necessary for 50% mortality
of Lemna minor 20
A.5.1 Toxicity of chlorophenols to aquatic organisms 28
A.6.1 Absorption of chlorophenols by humans and experimental
animals 34
A.6.2 Effect of chlorophenols on oxidative phosphorylation in
rat liver mitochondria 39
A.6.3 Local effects of chlorophenols on humans or experimental
animals 40
A.6.4 Acute toxicity of chlorophenols to experimental animals. . . 42
A.7.1 Degradation of chlorophenols in acclimated activated
sludge 53
A.7.2 Microbial decomposition of chlorophenols in soil
suspensions 55
B.2.1 Methods of determination of 2-chlorophenol and 2,4-
dichlorophenol in several sample materials 78
B.3.1 Metabolism of chlorophenols by an Avbhi'dbactey species
grown on 2,4-D or citrate 88
B.3.2 Inhibitory effect of phenolic compounds on Aspergilliis
nigev 90
B.4.1 Uptake of ^C-labeled 2,4-dichlorophenol by ten-day-old
oat and soybean plants from nutrient solutions contain-
ing 0.18 to 0.26 mg/liter 2,4-dichlorophenol 95
xv
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xvi
B.4.2 Uptake of 1AC-labeled 2,4-dichlorophenol by oats and
soybeans from soil containing 0.07 mg/kg of
2,4-dichlorophenol 96
B.4.3 Levels of 2,4-dichlorophenol and 2,4-D in aerial portions
of plants after treatment with 2,4-D 102
B.4.4 Levels of 2,4-dichlorophenol and 2,4-D in plants whose
roots were treated with 2,4-D 102
B.4.5 Effect of 2,4-dichlorophenol on mitotic abnormalities in
root preparations of Vic-La faba 103
B.4.6 Percentage of abnormal pollen mother cells after treatment
of Vioia faba with 2,4-dichlorophenol 104
B.5.1 Residues of 2,4-D and 2,4-dichlorophenol in sheep and
cattle fed 2,4-D for 28 days 108
B.5.2 Residues of 2,4-dichlorophenol in laying hens fed diets
containing nemacide [0-2,4-dichlorophenol)0,0-diethyl
phosphorothioate] for 55 weeks 109
B.5.3 Median tolerance limits of bluegill (Lepomis maarochLrus)
and trout (Salmo gairdnerii,') to 2-chlorophenol Ill
B.5.4 Respiratory median tolerance limits of trout tissues to
2-chlorophenol 112
B.6.1 Abundance of the principal urinary 2,4-dichlorophenol-
containing metabolites from hexachlorocyclohexane
isomers in the mouse 115
B.6.2 Histological changes in major organs of male mice (seven
animals per group) fed 2,4-dichlorophenol daily for six
months 119
B.6.3 Summary of data for 26 workers involved in manufacture of
2,4-dichlorophenol and 2,4,5-trichlorophenol 120
B.6.4 Appearance of skin tumors in mice treated cutaneously with
phenols following a cutaneous dose of 0.3% dimethyl-
benzanthracene in acetone 121
B.7.1 Production of 2,4-D compounds in the United States, 1967-
1975 124
B.7.2 Analysis of industrial plant waste from Hercules, Inc.,
Jacksonville, Arkansas, 1970 126
B.7.3 Relative chlorophenol content of industrial waste from
Hercules, Inc., Jacksonville, Arkansas, 1970 126
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xvii
B.7.4 Persistence of monochlorophenols added to several surface
waters at 20°C 128
B.7.5 Persistence of 2,4-dichlorophenol in lake water after addi-
tions of 100, 500, or 1000 yg/liter 2,4-dichlorophenol . . 129
B.7.6 Effect of temperature and pH on the degradation of
2-chlorophenol 132
B.7.7 Effect of concentration on the degradation of
2,4-dichlorophenol 132
B.7.8 Amount of clays required to reduce the concentrations of
2,4-dichlorophenol and 2,4-D compounds to 2.0 mg/liter . . 133
C.2.1 Methods of determination of 2,4,5-trichlorophenol, 2,4,6-
trichlorophenol, and tetrachlorophenols 164
C.3.1 Metabolism of 2,3,4,6-tetrachlorophenol by fungal isolates . 176
C.5.1 Residues of 2,4,5-T and 2,4,5-trichlorophenol in milk and
cream from cows fed 2,4,5-T 187
C.5.2 Applied versus measured concentrations of 2,4,6-trichloro-
phenol in a flow-through bioassay system 191
C.6.1 Chlorophenols detected in animal tissue or excretion
following administration of related organic compounds. . . 195
C.6.2 Residues of 2,4,5-T and 2,4,5-trichlorophenol in sheep fed
60 mg/kg 2,4,5-T daily for 28 days 197
C.6.3 Appearance of skin tumors in mice treated cutaneously with
phenols following a cutaneous dose of 0.3% dimethyl-
benzanthracene in acetone 204
C.7.1 Production of 2,4,5-trichlorophenol, 2,4,5-T, and silvex in
the United States, 1965-1975 208
C.7.2 Growth of the bacillus KC-3 in chlorophenol-mineral salts
media 215
C.7.3 Methylation of 2,4,6-trichlorophenol and 2,3,4,6-tetra-
chlorophenol by different fungal species 216
C.7.4 Adsorption of chlorinated phenoxyacetic acids by activated
carbon 221
D.2.1 Methods of determination of pentachlorophenol in several
sample materials 252
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xviii
D.2.2 Methods of determination of pentachlorophenol in several
sample materials containing other phenols 254
D.3.1 Antimicrobial efficiencies of pentachlorophenol 261
D.3.2 Growth inhibition of bacteria by pentachlorophenol 262
D.3.3 Length of lag phase and rate of growth of Trichoderma
viride, GHooladiwn vivide, and Cephaloascus fragrans
in malt agar containing sodium pentachlorophenate 264
D.3.4 Threshold values for pentachlorophenol toxicity to wood-
destroying fungi 266
D.3.5 Toxicity of pentachlorophenol and sodium pentachlorophenate
to fungi 267
D.3.6 Effects of pentachlorophenol (0.01 mole/liter) on spore
germination, growth, and sporulation of Helminthosporiton
oryzae, Altemcaria solan-i, and Ciupvulapia lunata 268
D.3.7 Control of Chora and Nitella species with chemicals applied
60 days after transplanting the paddy 269
D.4.1 Distribution of [1AC]pentachlorophenol in sugar cane after
foliar application 272
D.4.2 Distribution of [1*C]pentachlorophenol in sugar cane grown
for four weeks in pentachlorophenol-treated nutrient
solution and transferred to pentachlorophenol-free
solution 273
D.4.3 Effect of pentachlorophenol preservative treatment of
wooden flats on the growth of tomato plants 276
D.4.4 Death or injury to conifer seedlings grown in
pentachlorophenol-treated wooden trays 277
D.4.5 Death or injury to red and jack pine seedlings grown in
pentachlorophenol-treated flats 278
D.4.6 Effect of pentachlorophenol on mitotic abnormalities in
root preparations of Vioia faba 280
D.5.1 Mortality of pigs farrowed in crates treated with
pentachlorophenol 283
D.5.2 Retention of pentachlorophenol in various biological
materials from swine drenched with a solution containing
5% pentachlorophenol, 5% diacetone alcohol, and 90%
mineral spirits 285
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XIX
D.5.3 Variability of pentachlorophenol levels in blood of five
sheep force-fed pentachlorophenol-impregnated sawdust. . . 285
D.5.4 Comparison of average weight of pigs involved in experi-
ments to determine toxicity of pentachlorophenol 289
D.5.5 Pentachlorophenol in composite samples of snails, frogs,
and fish collected in rice fields at Wageningen,
Surinam, November 1971 290
D.5.6 Pesticide residues in 17 snail kites found dead at a
roost adjacent to rice fields at Wageningen, Surinam,
November 27-28, 1971 291
D.5.7 Comparison of pentachlorophenol residues in snail kites
foraging in pentachlorophenol-treated rice fields and
those in a freshwater marsh at Wageningen, Surinam,
November 29 — December 3, 1971 292
D.5.8 Pentachlorophenol residues in composite tissue samples of
birds and spectacled caiman collected on rice fields at
Wageningen, Surinam, October 21-31, 1971 293
D.5.9 Chronic toxicity dose rates and effects of pentachloro-
phenol on treated sheep 294
D.5.10 Chronic toxicity dose rates and effects of pentachloro-
phenol on treated calves 294
D.5.11 Detection thresholds for chloroanisoles in aqueous
solution 296
D.5.12 Chlorophenol and chloroanisole levels in fresh shavings
and spent litter from broiler chicken houses 296
D.5.13 Pentachlorophenol levels in fish and water downstream from
a pulp mill 297
D.5.14 Distribution of pentachlorophenol in the short-necked clam
(Tapes phi-lippincanon) 300
D.5.15 Changes in amount of pentachlorophenol accumulated in
goldfish tissues during exposure to a medium containing
0.2 mg/liter [14C]pentachlorophenol 303
D.5.16 Changes in retention of pentachlorophenol in goldfish
tissues during culture in running water after a 24-hr
exposure to a 0.2 mg/liter [li'C]pentachlorophenol medium . 304
D.5.17 Distribution of pentachlorophenol and degradation products
in a model aquatic ecosystem 308
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XX
D.5.18 Biodegradability indexes of organic chemicals determined
for mosquito fish in a model aquatic ecosystem 309
D.5.19 Acute toxicity of pentachlorophenol to aquatic organisms . . 313
D.5.20 Chronic effects of pentachlorophenol on aquatic organisms. . 318
D.5.21 Metabolic effects of pentachlorophenol (0.1 mg/liter) on
eels in freshwater 319
D.5.22 Metabolic effects of pentachlorophenol (0.1 mg/liter) on
eels in seawater 320
D.5.23 Effects of pentachlorophenol on the eel 321
D.5.24 Summary of results reported by seven laboratories using
sodium pentachlorophenate as a reference toxicant for
salmonid bioassays 322
D.5.25 The 48- and 96-hr LC50 values and the lethal threshold
concentration of sodium pentachlorophenate for fathead
minnows at 15°C and 25°C 323
D.5.26 Ecological magnification of organic chemicals by mosquito
fish in a model aquatic ecosystem 325
D.5.27 Distribution of hexachlorobenzene and degradation products
in a model aquatic ecosystem 326
D.6.1 Inhalation of pentachlorophenol by two human subjects and
recovery in urine 335
D.6.2 Residues of pentachlorophenol in urine of individual after
cutaneous absorption 342
D.6.3 Levels of pentachlorophenol in serum and urine from
healthy persons at a hospital where a pentachlorophenol
poisoning incident occurred 344
D.6.4 Minimum lethal doses of pentachlorophenol and sodium
pentachlorophenate applied cutaneously to experimental
animals 345
D.6.5 Autopsy analyses of two humans fatally poisoned by
pentachlorophenol 349
D.6.6 Content of pentachlorophenol in tissues of a fatally
poisoned infant 349
D.6.7 Autopsy report on 16-year-old patient fatally poisoned
with pentachlorophenol 350
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XXI
D.6.8 Autopsy findings from three persons fatally poisoned
with pentachlorophenol 350
D.6.9 Concentration of pentachlorophenol in tissues of rabbits
after cutaneous application of 10 ml of 1% aqueous
sodium pentachlorophenate for 100 consecutive days,
except Sundays 352
D.6.10 Distribution of pentachlorophenol in tissues of two rab-
bits following oral doses of sodium pentachlorophenate . . 352
D.6.11 Excretion and distribution of [1/JC]pentachlorophenol after
intraperitoneal injection 353
D.6.12 Pentachlorophenol biotransformation in mammals 358
D.6.13 Recovery of pentachlorophenol in the carcasses and excreta
of rats following a single intraperitoneal dose of 2.4
mg pentachlorophenol per animal 361
D.6.14 Carbon-14 activity in urine collected 0 to 24 hr after
intraperitoneal injection of [lfcC]pentachlorophenol in
mice 362
D.6.15 Carbon-14 activity in urine of rats and mice receiving 10
to 25 mg/kg pentachlorophenol in a single intraperitoneal
dose 364
D.6.16 Pharmacokinetics of pentachlorophenol in rats 371
D.6.17 Effects of various concentrations of pentachlorophenol on
snail tissue and rat liver in vitro 374
D.6.18 Enzyme inhibition by pentachlorophenol 375
D.6.19 Activity of microsomal liver enzymes in rats maintained on
diets containing pentachlorophenol for 12 weeks 380
D.6.20 Pentachlorophenol levels in urine of fatally and nonfatally
poisoned humans. 383
D.6.21 Lethal doses of pentachlorophenol and sodium pentachloro-
phenate administered orally and cutaneously to rats,
rabbits, and guinea pigs 384
D.6.22 Clinical effects of cutaneous administration of sodium
pentachlorophenate to rabbits 386
D.6.23 Comparison of the toxicities of pentachlorophenol and
sodium pentachlorophenate to rabbits 386
D.6.24 Chronic toxicity of sodium pentachlorophenate to rabbits . . 387
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XX11
D.6.25 Toxicity of pentachlorophenol to rats in a 12-week
feeding study 39°
D.6.26 Histopathology of liver and kidney tissues following oral
administration of pentachlorophenol to rats for 12 weeks . 392
D.6.27 Hepatic effects of pure and technical grade pentachloro-
phenol in female rats during an eight-month feeding
study 393
D.6.28 Comparison of the toxicities of pure and technical grade
pentachlorophenol in male rats in a 90-day study 394
D.6.29 Toxicity of pentachlorophenol with a low nonphenolic
content to rats during a 90-day study 396
D.6.30 Chronic toxicity of pentachlorophenol with low nonphenolic
content to male and female rats 397
D.6.31 Concentrations of pentachlorophenol in urine of Hawaiians. . 399
D.6.32 Concentration range of pentachlorophenol in human urine. . . 400
D.6.33 Pentachlorophenol concentrations in air from plants and
urine of mill workers in Oregon 401
D.6.34 Pentachlorophenol levels in adipose tissue of nonoccupa-
tionally exposed persons 402
D.6.35 Cases of pentachlorophenol-related health problems
reported by employees of wood preserving plants operated
by the Koppers Company over a ten-year period 404
D.6.36 Average incidence and daily intake of pentachlorophenol
in food in the United States 404
D.6.37 Average daily intake of pentachlorophenol from eight food
classes in the United States 405
D.6.38 Levels of pentachlorophenol in 24-hr composite influent
and effluent samples and total pentachlorophenol output
from sewage treatment plants in Oregon 406
D.6.39 Concentration and removal of pentachlorophenol at various
stages of the water treatment process at the Taylor
Plant in Corvallis, Oregon 407
D.6.40 Incidence of primary tumous (based on histopathological
diagnosis) in rats fed pentachlorophenol for 22 months
(males) and 24 months (females) 410
D.7.1 Producers of pentachlorophenol in the United States 420
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xxiii
D.7.2 Pentachlorophenol in rainwater, Oahu, Hawaii, 1971-1972. . . 421
D.7.3 Air contaminant control methods used in pentachlorophenol
manufacture 423
D.7.4 Concentration of pentachlorophenol in aquatic fauna and
commercial fish food in New Brunswick, Canada 426
D.7.5 Simple correlation coefficients relating degradation rate
of pentachlorophenol to properties of soils 430
D.7.6 Persistence of pentachlorophenol in soil 432
D.7.7 Determination of pentachlorophenol in soil surrounding
pentachlorophenol-treated utility poles 433
D.7.8 Oxidation of pentachlorophenol by a heterogeneous accli-
mating biomass 437
D.7.9 Leaching of pentachlorophenol from "penta sludges" in soil
in 205 days 438
D.7.10 Snail eggs killed within 24 hr by irradiated and untreated
solutions when each solution was diluted to the sodium
pentachlorophenate concentration 441
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FOREWORD
A vast amount of published material is accumulating as numerous
research investigations are conducted to develop a data base on the
adverse effects of environmental pollution. As this information is
amassed, it becomes continually more critical to focus on pertinent,
well-designed studies. Research data must be summarized and interpreted
in order to adequately evaluate the potential hazards of these substances
to ecosystems and ultimately to public health. The Reviews of the Environ-
mental Effects of Pollutants (REEPs) series represents an extensive com-
pilation of relevant research and forms an up-to-date compendium of the
environmental effect data en selected pollutants.
Reviews of the Environmental Effects of Pollutants: XI. Chlorophenols
includes information on chemical and physical properties; pertinent
analytical techniques; transport processes to the environment and sub-
sequent distribution and deposition; impact on microorganisms, plants,
and wildlife; toxicologic data in experimental animals including metabo-
lism, toxicity, mutagenicity, teratogenicity, and carcinogenicity; and an
assessment of its health effects in man. The large volume of factual
information presented in this document is summarized and interpreted in
the final chapter, "Environmental Assessment," which presents an overall
evaluation of the potential hazard resulting from present concentrations
of chlorophenols in the environment. This final chapter represents a major
contribution by Gary A. Van Gelder from the University of Missouri.
The REEPs are intended to serve various technical and administrative
personnel within the Agency in the decision-making processes, i.e., in
the development of criteria documents and environmental standards, and
for other regulatory actions. The breadth of these documents makes them
a useful resource for public health personnel, environmental specialists,
and control officers. Upon request these documents will be made available
to any interested individuals or firms, both in and out of the government.
Depending on the supply, the document can be obtained directly by writing
to:
Dr. Jerry F. Stara
U.S. Environmental Protection Agency
Health Effects Research Laboratory
26 W. St. Clair Street
Cincinnati, Ohio 45268
R. J. Garner
Director
Health Effects Research Laboratory
xxv
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ACKNOWLEDGMENTS
The authors would like to underscore their appreciation to the follow-
ing Water Resources Center staff who were instrumental in the preparation
of this report: Ms. Karen Sy for her outstanding efforts in implementing
and coordinating the literature searches and data acquisition; Mr. Frank
Priznar for his preview and categorization of the documents; Mr. Glenn
Harold for his drafting efforts and tolerance of change; Mr. J. Peter Wall
for his comments on the preparation of the manuscript; Ms. Cindy Geller,
whose efforts in typing the original manuscript cannot be overstated; and
Mrs. Frances Johnson and Mrs. Rita Chilton for their typing contributions.
The authors are grateful to Dr. Roger Rowell of the U.S. Forest
Products Laboratory for his assistance and advice during preparation of
the manuscript and to Ms. Anna Hammons and Dr. Gerald Ulrikson of Oak Ridge
National Laboratory and Dr. Jerry Stara, EPA Project Officer, for their
invaluable advice and assistance. The authors also thank Carol McGlothin,
editor, and Donna Stokes and Patricia Hartman, typists, of Oak Ridge
National Laboratory for preparing the manuscript for publication.
Appreciation is also expressed to Bonita M. Smith, Karen L. Blackburn,
and Donna J. Sivulka for EPA in-house reviews and editing and for coordi-
nating contractual arrangements. The efforts of Allan Susten and Rosa
Raskin in coordinating early processing of the reviews were important in
laying the groundwork for document preparation. The support of R. John
Garner, Director of Health Effects Research Laboratory, is much appreci-
ated. Thanks are also expressed to Carol A. Haynes for typing correspond-
ence and corrected reviews.
xxvii
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ABSTRACT
This study reviews the health and environmental effects of chloro-
phenols. It includes discussions of physical and chemical properties;
analytical methods; biological aspects in microorganisms, plants, animals,
and humans; environmental distribution and transformation; and environ-
mental interactions and their consequences. All of the economically or
environmentally important chlorophenol isomers are reviewed: 2-chloro-
phenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol,
tetrachlorophenols, and pentachlorophenol. Approximately 400 references
are cited.
2-Chlorophenol is used mainly as a starting material for further
chlorination to 2,4-dichlorophenol, 2,4,6-trichlorophenol, and penta-
chlorophenol. Similarly, 2,4-dichlorophenol and 2,4,5-trichlorophenol
are utilized principally as intermediates for the synthesis of 2,4-
dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid
(2,4,5-T) respectively. 2,4,5-Trichlorophenol, 2,4,6-trichlorophenol,
2,3,4,6-tetrachlorophenol, and their salts are important germicides for
the preservation of wood, glue, latex, leather, and textiles. Penta-
chlorophenol has been widely used as a fungicide for wood preservation.
The toxicity of the chlorophenol isomers to higher organisms increases
with increased chlorine substitution. Pentachlorophenol is the most toxic
of the isomers. Fish kills, extensive losses of wildlife, toxic effects
in domestic animals, and human fatalities have resulted from exposure to
pentachlorophenol. Available evidence indicates that moderate bioconcen-
tration and biomagnification of pentachlorophenol may occur in aquatic
organisms.
The primary source of human exposure to chlorophenols (except penta-
chlorophenol) is likely the degradation of chemically related phenoxy-
alkanoic herbicides such as 2,4-D and 2,4,5-T. Use of pentachlorophenol
as a wood preservative is the major source of human exposure. Chlorina-
tion of drinking water or wastewater may result in the production of
chlorophenols. Several isomers possess potent organoleptic properties.
Pentachlorophenol is ubiquitous in the environment. Low, but detectable,
levels have been found in river water, municipal water supplies, human
foodstuffs, and in the blood, urine, and fat of nonoccupationally exposed
humans. The exact sources of these residues have not been identified.
Monitoring data on the other chlorophenol isomers are not available.
Chronic toxicity of chlorophenols to humans has not been documented.
Available data indicate that chlorophenols do not possess tumorigenic,
mutagenic, or teratogenic properties. Several isomers may be embryotoxic.
2-Chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol may promote
tumors in mice. Available data fail to suggest a direct carcinogenic
potential of any of the isomers reviewed.
This report was submitted in partial fulfillment of Interagency Agree-
ment No. D5-0403 between the Department of Energy and the U.S. Environ-
mental Protection Agency. The draft report was submitted for review in
July 1977. The final report was completed in November 1978.
xxix
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PART A
SUMMARY OF COMPARATIVE RELATIONSHIPS OF CHLOROPHENOLS
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A.I INTRODUCTION
Part A provides a comparative overview of the environmental effects
of chlorophenols. Whenever possible, comparisons are made among the
compounds 2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol,
2,4,6-trichlorophenol, tetrachlorophenols, and pentachlorophenol. A
lack of information indicates that valid comparisons based on the avail-
able data cannot be made. In the interest of clarity and readability,
brief summary statements are occasionally used when individual compounds
are discussed even though a lack of adequate data on the other compounds
precludes a comparative statement. No attempt is made to summarize the
data and conclusions completely. More detailed and complete summaries
of the environmental and biological aspects of these compounds are found
at the beginning of Parts B, C, and D of the report. In Part A, refer-
ence citations are used only when specific data are presented in tabular
form. The reader is referred to individual sections and their bibliog-
raphies for complete reference information.
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A.2 PHYSICAL AND CHEMICAL PROPERTIES AND ANALYSIS
A.2.1 PHYSICAL PROPERTIES
All chlorophenols listed in Table A.2.1 are solids at room tempera-
ture except 2-chlorophenol, which is a liquid. They have pungent, medic-
inal odors which are more intense and persistent with 2-chlorophenol
and 2,4-dichlorophenol. A wide variation in boiling points, which
increase with increased chlorination, exists among chlorophenols. This
variation allows convenient separation of the chemicals by fractional
distillation. They can be steam distilled, but only 2-chlorophenol vola-
tilizes from aqueous alkaline solutions. Chlorophenols behave as weak
acids, and the acidity increases with increased chlorination, as shown
by the dissociation constants. This behavior implies that ionization of
higher chlorophenols in aqueous solutions occurs over a wider pH range
(i.e., pentachlorophenol begins to dissociate at a pH of about 3.5, but
2-chlorophenol does not dissociate below pH 7). Dissociation of the
chemicals influences their sorption on colloids and their toxicological
properties. The toxicity of 2,4,6-trichlorophenol and pentachlorophenol
to fungi is decreased as the degree of dissociation increases. Volatility
and water solubility of chlorophenols decrease with increasing degree of
chlorination. Although their solubility in water is low, they are readily
soluble in many organic solvents. Partition coefficients in favor of the
organic solvents facilitate isolation of the compounds for analysis.
A.2.2 MANUFACTURE
Two main processes are presently utilized in the manufacture of
chlorophenols (Table A.2.2). The chemistry of these processes is wel'l
known and no patent currently exists. With the exception of 2,4,5-
trichlorophenol, commercial synthesis of chlorophenols involves the
direct chlorination of phenol to various extents until the desired prod-
uct is obtained. The production of 2,4,5-trichlorophenol is accomplished
by hydrolysis of 1,2,4,5-tetrachlorobenzene with sodium hydroxide.
A.2.3 USES
2-Chlorophenol is used mainly as a starting material for further
chlorination to 2,4-dichlorophenol, 2,4,6-trichlorophenol, and penta-
chlorophenol (Table A.2.2). Similarly, 2,4-dichlorophenol and 2,4,5-tri-
chlorophenol are utilized principally as intermediates for the synthesis
of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxy-
acetic acid (2,4,5-T) respectively. 2,4,5-Trichlorophenol, 2,4,6-tri-
chlorophenol, 2,3,4,6-tetrachlorophenol, and their salts are important
germicides for the preservation of wood, glue, latex, leather, and
textiles. Pentachlorophenol has been widely used as a fungicide for
wood preservation.
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TABLE A.2.1. PHYSICAL PROPERTIES OF CHLOROPHENOLS
Property
Empirical formula
Molecular weight
Melting point, °C
Boiling point, °C
Density, g/cm"
Vapor pressure,
mm Hgd
Dissociation constant
(at 25°C)
Solubility, g/100 g
solvent
Water
Mcthanol
Dlethyl ether
Ethanol
Acetone
Xylenc
Benzene
Carbon
tetrachlorlde
Rtlier
Cliloroform
Methyl chloride
Toluene-
2-Chlorophenol
C.HsCIO
128.56
9
175
1.24 (18/15)h
1 (12.1°C)
3.2 x 10-*
2.85 (20"C)
a
a
>200
Soluble
a
Very soluble
7
>200
a'
a
a
2,4-Dichloro-
phenol
C.lUCljO
163.01
45
210
1.38 (60/7)h
1 (53°C)
2.1 x 10'°
0.45 (20°C)
a
a
Very soluble
j
a
Very soluble
a
Very soluble
Very soluble
Very soluble
a
2,4,5-Trl-
chlorophenol
C.HjCljO
197.46
66-67
245-246
1.68 (25/25)°
1 (72°C)
3.7 x 10'8
Slightly
soluble
615
1
ti
615
a
163
a
11
a
a
a
2,4,6-Trl-
chlorophenol
C.H,C1,0
197.46
68
246
1.49 (75/4)fc
1 (76.5°C)
3.8 x 10-'
Slightly
soluble
525
a
I!
500
a
113
«
Very soluble
a
a
100
2,3,4,6-Tetra-
chlorophenol
C.HiCUO
231.91
69-70
Decomposes at
150°C at 16
nun llg
a
1 (100°C)
4.2 x lO'"
0.01 (25°C)
319
1
a
570
a
a
a
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TABLE A.2.2. SYNTHESIS, USES, AMD REACTIONS OF CHLOROPHENOLS
Compound
Commercial synthesis
Principal uses
Important reactions
2-Chlorophenol
Direct chlorination of phenol
2,4-Dichlorophenol Direct chlorination of phenol
2,4,5-Tri-
chlorophenol
2,4,6-Tri-
chlorophenol
2,3,4,6-Tetra-
chlorophenol
Pentachlorophenol
Hydrolysis of 1,2,4,5-tetra-
chlorobenzene
Direct chlorination of phenol
Direct chlorination of phenol
or chlorination of lower
chlorophenols
Direct chlorination of phenol
or chlorination of lower
chlorophenols
Starting material for further
chlorination to 2,4-dichloro-
phenol, 2,4,6-trichlorophenol,
and pentachlorophenol
Intermediate for production of
2,4-D; ingredient of anti-
septics
Intermediate in manufacture of
2,4,5-T and related herbicides;
fungicide and bactericide
Germicide, particularly for
preservation of wood, leather,
glue, and textiles; ingredient
in preparation of insecticides
and soap germicides
Fungicide and bactericide for
latex, wood, and leather
preservation; insecticide
Fungicide, chiefly for wood
preservation; herbicide and
general biocide
Substitution in aromatic ring; phenolic
group undergoes etherification, ester-
ification, and condensation reactions
and reacts with metallic salts
Substitution in aromatic ring; phenolic
group undergoes etherification, ester-
ification, and condensation reactions
and reacts with metallic salts
Substitution in aromatic ring; phenolic
group undergoes etherification, ester-
ification, and condensation reactions
and reacts with metallic salts
Substitution in aromatic ring; phenolic
group undergoes etherification, ester-
ification, and condensation reactions
and reacts with metallic salts
Phenolic group reacts with metallic
salts
Phenolic group reacts with metallic
salts
Lower chlorophenols include 2-chlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol.
Source: Compiled from Doedens, 1963; Dow Chemical Company, undated; Freiter and Schneider, 1977.
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A.2.4 CHEMICAL REACTIVITY
Chlorophenols undergo several reactions; some of the important ones
are listed in Table A.2.2. Substitution readily occurs in the aromatic
ring of 2-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol.
Further chlorination of 2-chlorophenol results in the formation of 2,4-
and 2,6-dichlorophenol; 2,4-dichlorophenol reacts to form 2,4,6-tri-
chlorophenol, and 2,4,6-trichlorophenol is converted to 2,3,4,6-tetra-
chlorophenol and pentachlorophenol. Bromination of 2-chlorophenol,
2,4-dichlorophenol, and 2,4,6-trichlorophenol yields the monosubstituted
and disubstituted derivatives. Direct nitration is possible for 2-chloro-
phenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol to the monosubsti-
tuted and disubstituted derivatives. The phenolic group of chlorophenols
undergoes interesting reactions which yield important pesticidal and
germicidal compounds. For example, the herbicides 2,4-D and 2,4,5-T
are synthesized by the etherification of 2,4-dichlorophenol and 2,4,5-
trichlorophenol, respectively, with monochloroacetic acid. Metal
chlorophenates are prepared easily by reacting the phenolic group with
metal salts in the presence of organic solvents. The salt forms of
chlorophenols are more soluble in water but are less soluble in organic
solvents.
Most of the reactions described can only be performed under con-
trolled laboratory conditions. However, conversion of 2-chlorophenol to
2,4- and 2,6-dichlorophenol and of 2,4-dichlorophenol to 2,4,6-trichloro-
phenol may occur during the chlorination of drinking water and waste-
water. These reactions are of great concern because dichlorophenols have
been implicated as the compounds contributing largely to the objection-
able phenolic odor and taste of water.
A.2.5 TRANSPORT AND TRANSFORMATION IN THE ENVIRONMENT
The transport and transformation mechanisms of chlorophenols in the
atmosphere, soils, and aquatic environment are summarized in Section A.7.
A.2.6 ANALYSIS
Common procedures for sample collection and preservation, sample
preparation for analysis, and determination are used for all chloro-
phenols. Electron-capture gas-liquid chromatography is the method of
choice for the separation, identification, and quantification of low
levels of chlorophenols found in a wide variety of environmental samples.
This rapid and sensitive method provides excellent simultaneous resolu-
tion of chlorophenol isomers. The aminoantipyrine colorimetric method,
although simple and rapid, lacks specificity and is limited to gross
determination of chlorophenols or to a single isomer present in a
relatively high concentration.
-------
8
SECTION A.2
REFERENCES
1. Bevenue, A., and H. Beckman. 1967. Pentachlorophenol: A Discus-
sion of Its Properties and Its Occurrence as a Residue in Human and
Animal Tissues. Residue Rev. 19:83-134.
2. Deichmann, W. B., and M. L. Keplinger. 1963. Phenols and Phenolic
Compounds. In: Industrial Hygiene and Toxicology, 2nd ed., Vol. 2,
Toxicology, D. W. Fassett and D. D. Irish, eds. John Wiley and Sons,
Interscience Publishers, New York. pp. 1363-1408.
3. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons,
Interscience Publishers, New York. pp. 325-338.
4. Dow Chemical Company. Undated. Organic Chemicals from Dow — Chlo-
rinated Aromatics. Midland, Mich. 11 pp.
5. Freiter, E. R., and J. A. Schneider. 1977. Personal Communication.
6. Weast, R. C., ed. 1975. Handbook of Chemistry and Physics, 56th ed.
CRC Press, Cleveland, pp. C470-C471.
-------
A.3 BIOLOGICAL ASPECTS IN MICROORGANISMS
A.3.1 BACTERIA
A.3.1.1 Metabolism
2-Chlorophenol and 2,4-dichlorophenol are amenable to metabolism by
bacteria found in soil and aquatic environments. Phenol-adapted bacteria
isolated from soil rapidly metabolize 2-chlorophenol to produce 3-chloro-
catecol (3-chloro-l,2-dihydroxybenzene). Microbial breakdown proceeds
further to include ring cleavage. Soil bacteria capable of growing on
and degrading 2,4—dichlorophenoxyacetic acid (2,4-D) are also adapted to
metabolism of 2-chlorophenol and 2,4-dichlorophenol. Degradation by
these bacteria proceeds through the formation of 3,5-dichlorocatechol to
eventually form dicarboxylic acids, acetate, and chloride. ^Metabolic
breakdown of 2-chlorophenol and 2,4-dichlorophenol also occurs in the
presence of certain aquatic bacteria, principally those found in acti-
vated sludge. The presence of these bacteria is extremely important for
the biological treatment of waste generated from the manufacture of
chlorophenols and 2,4-D.
Effective microbial degradation of trichlorophenol and tetrachloro-
phenol has been demonstrated in activated sludge, lagoon effluent, and
enrichment cultures. Thus, effective waste treatment of chlorophenol-
containing wastewaters likely occurs when appropriate bacterial populations
are present. Microorganisms capable of metabolizing trichlorophenols and
tetrachlorophenols have not been isolated from soils, nor have degradation
pathways been elucidated. More research is warranted to determine whether
bacteria capable of metabolizing higher chlorophenols are widespread in
the environment.
Although pentachorophenol is the most refractory of the chlorophenol
compounds to microbial degradation, bacteria capable of pentachlorophenol
metabolism have been found in soil, water, pentachlorophenol-treated wood,
and sewage treatment plants exposed to pentachlorophenol-containing efflu-
ents . Certain soil bacteria are able to detoxify pentachlorophenol by
methylation, forming pentachloroanisole. Other bacterial strains isolated
from continuous-flow enrichment cultures are able to metabolize penta-
chlorophenol quantitatively with the release of chloride, quantitative
disappearance of the substrate, and almost quantitative oxygen uptake.
Most bacterial strains capable of degrading pentachlorophenol readily
either have been isolated from areas where the compound is commonly found
or have been artificially developed in the laboratory, utilizing gradual
enrichment and acclimation of the bacteria to increasing levels of penta-
chlorophenol. The extent to which pentachlorophenol-metabolizing bacteria
are present in the environment is not known. In most cases, rapid penta-
chlorophenol metabolism depends on gradual acclimation. Thus, the hazard
posed by pentachlorophenol in environments where the compound has not
previously been present may be increased.
-------
10
A.3.1.2 Effects
All chlorophenols possess bactericidal properties; the potency gener-
ally increases with the degree of chlorine substitution up to the trichloro
derivatives. The tetrachloro isomers are considerably less active than any
of the trichloro isomers; pentachlorophenol is less effective than the
tetrachloro isomers and is about as effective as phenol itself. However,
some of the higher chlorophenols, particularly pentachlorophenol, have en-
hanced fungicidal activity. The antibacterial action of phenolic compounds
involves several steps: adsorption to the bacterial cell wall, inactiva-
tion of essential enzymes, and finally lysis and death of the cell. Phe-
nolic compounds bind and denature proteins and, at high concentrations,
act as gross protoplasmic poisons which penetrate rapidly and rupture
the cell wall. However, chlorophenols are frequently toxic at levels too
low to denature proteins. Thus, another mechanism must be operative at
these lower concentration levels. Some studies of the mechanism of
action of chlorophenols have indicated that cell membrane damage is a
primary effect. Association with cellular lipids and subsequent altera-
tion of cell permeability may be responsible for the toxicity of many
chlorophenols.
Other mechanisms for toxicity may be operative in the case of higher
chlorophenols. Pentachlorophenol and the tetrachlorophenols are potent
uncouplers of oxidative phosphorylation, and it is believed that this
effect is of major importance in the toxicity of pentachlorophenol (and
likely the tetrachlorophenols) to bacteria. However, many bacteria which
are susceptible to control by pentachlorophenol depend primarily on anaer-
obic fermentation as an energy source. Thus, a mechanism for pentachloro-
phenol toxicity must include an explanation for the sensitivity of anaerobes
to this compound. Although the mechanism of this effect on anaerobes is not
understood, results have indicated that pentachlorophenol affects the genera-
tion of ATP by substrate-level phosphorylation. Additionally, the inhibition
of glycolytic enzymes demonstrated in higher animals may be responsible for
the effect noted in bacteria, although no information addressing this point
was found.
Although chlorophenols are effective microbicides and several of the
compounds find primary usage as disinfectants, detailed data on the rela-
tive toxicity of chlorophenols to bacteria are not available. Antibacterial
effectiveness of higher chlorophenols is presented in Table A.3.1. Un-
fortunately, bactericidal activities of lower chlorophenols have been
described in the literature only in terms of phenol coefficients. Thus,
direct comparison of the relative toxicities of the chlorophenols is
difficult. Bactericidal activities of lower chlorophenols and of 2,4,6-
trichlorophenol are presented in Table A.3.2. The phenol coefficient'
measures, under identical conditions, the highest dilution of the test
disinfectant effective to kill in 10 min relative to phenol. Thus, dis-
infectants with phenol coefficients greater than 1 are more potent!
Because the data in Tables A.3.1 and A.3.2 cannot be compared directly,
only generalizations are possible in assessing the relative antibacterial
effectiveness of the compounds. In general, antibacterial effectiveness
apparently improves with increased chlorine substitution up to the tri-
chloro derivatives.
-------
TABLE A.3.1. ANTIBACTERIAL EFFICIENCIES OF THE HIGHER CHLOROPHENOLS
Compound
Test organism
Chlorophenol
concentration for
complete inhibition
(mg/liter)
Source
Sodium 2,4,5-trichlorophenate
2
2
, 4 , 5-Trichlorophenol
,3,4, 6-Tetrachlorophenol
Pentachlorophenol
Pseudomonas aeruginosa
Enterobacter aerogenes
Bacillus subtilis
Flavobacterium arborescens
Aerobacter aerogenes
Bacillus mycoides
Aerobacter aerogenes
Bacillus mycoides
Bacillus cereus var. mycoides
Bacillus subtilis
Escherichia coli
Pseudomonas aeruginosa
Enterobacter aerogenes
Streptomyces griseus
Flavobacterium arborescens
300-400
25-50
10-25
10-25
20
15
400
7
5-10
50-100
250-500
1000-2500
500-1000
5-10
2.5-5
Dow Chemical Company, 1969a
Dow Chemical Company, 1969<2
Dow Chemical Company, 1969a
Dow Chemical Company, 1969a
Walko, 1972
Walko, 1972
Walko, 1972
Walko, 1972
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow dhemical Company, undated
Dow Chemical Company, undated
-------
12
TABLE A.3.2. BACTERICIDAL ACTIVITIES OF
HALOGENATED PHENOLS
Phenol coefficient at 37 °C
Compound
Phenol (unsubstituted)
2-Chlorophenol
4-Chlorophenol
2 , 4-Dichlorophenol
2,4, 6-Trichlorophenol
4-Methyl-2-chlorophenol
4-Ethyl-2-chlorophenol
4-n-Butyl-2-chlorophenol
4-n-Heptyl-2-chlorophenol
2-Methyl-4-chlorophenol
2-Ethyl-4-chlorophenol
2-n-Butyl-4-chlorophenol
2-n-Heptyl-4-chlorophenol
Salmonella
typhosa
1.0
3.6
3.9
13.3
23.0
17.2
6.3
86.0
16.7
28.6
12.5
146.0
20.0
Staphy lococaus
aureus
1.0
3.7
4.6
12.7
25.0
15.7
7.5
94.0
375.0
34.4
12.5
257.0
1500.0
Source: Compiled from Sykes, 1965, Table 33, p. 314,
and Baker, Schumacher, and Roman, Tables 26.1 and 26.2, p.
632. Data collected from several sources. Reprinted by per-
mission of the publishers.
In view of the potent antimicrobial activity of chlorophenols, any
of these compounds may pose a threat to sewage treatment plants which
have not been previously exposed to them. On the other hand, sewage
treatment plants regularly exposed to chlorophenols can probably be
operated safely with adequate degradation of chlorophenols. In many
cases, pentachlorophenol does not exhibit any detectable biochemical
oxygen demand (BOD). Because BOD determinations are commonly used in
assessing the effectiveness of sewage treatment processes, pentachloro-
phenol (in the absence of pentachlorophenol-adapted bacteria) will not
be detected as a component of the measured BOD, and the compound could
conceivably be released from the facility in the absence of other diag-
nostic tools for its determination.
A. 3.2 FUNGI
A.3.2.1 Metabolism
Oxidases (lactase, tyrosinase, and peroxidase) found in white rot
fungi are believed to be involved in the degradation of ehlorophenols.
Most of the information regarding fungal metabolism of chlorophenols is
-------
13
derived from studies of musty taint in broiler chickens. Musty taint
results from the uptake of anisoles (formed by methylation of chloro-
phenols in poultry litter) by chickens, causing an unappetizing taint in
the chicken meat. 2,4,6-Trichlorophenol, 2,3,4,6-tetrachlorophenol, and
pentachlorophenol are methylated readily by fungi present in poultry
litter. Removal of chlorophenols from broiler house litter, whether by
methylation or by another mechanism, probably involves many different
species of fungi and more than one metabolic route. The degradation of
2-chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol by fungi
is not well documented. It is believed that fungal metabolism through
methylation probably occurs if appropriate fungal strains are present.
The mechanism of chlorophenol detoxification by fungi is not well under-
stood. Methylation of the compound may be a primary step in detoxifica-
tion, and production of compounds such as quinones, chloranil, and
tetrachlorobenzoquinone may result from further metabolism of the com-
pounds . The extent to which fungal metabolism contributes to dissipation
of chlorophenols from the environment is not known, and further research
is warranted.
A.3.2.2 Effects
Information on the mechanism of action of chlorophenols on fungi is
not available. Toxicity of chlorophenols to fungi may result from mech-
anisms similar to those discussed for bacteria (Section A.3.1.2). Reported
effects on oxidative phosphorylation, particularly with respect to higher
chlorophenols, may also be important in the toxicity of these compounds
to fungi. 2,4,5-Trichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetra-
chlorophenol, and pentachlorophenol are commonly used as preservatives
and general purpose microbicides. The antifungal activity of these com-
pounds has been documented; their toxicity to various species of fungi
is presented in Table A.3.3. No information on the antifungal activity
of 2-chlorophenol and 2,4-dichlorophenol was found.
A. 3.3 ALGAE
A.3.3.1 Metabolism
No information is available on the metabolism of chlorophenols by
algae.
A.3.3.2 Effects
Chlorophenols are toxic to algae. Their toxicity to algae has been
studied under laboratory conditions and expressed in terms of effects on
chlorophyll synthesis (Table A.3.4). Table A.3.5 lists the toxicity
constants for chlorophenols. Increasing the number of chlorine atoms on
the aromatic rings of chlorophenols enhances their toxicity. The tri-
chlorophenol isomers, 2,4,5- and 2,4,6-trichlorophenol, are at least 100
times more toxic to algae than either 2-chlorophenol or 2,4-dichloro-
phenol. Pentachlorophenol is extremely toxic to algae and is the most
toxic compound among the ten halogenated phenols tested for their effects
on chlorophyll synthesis. Even at concentrations as low as 1.5 mg/liter,
-------
TABLE A.3.3. ANTIFUNGAL EFFICIENCIES OF CHLOROPHENOLS
Compound
Test organism
Chlorophenol
concentration for
complete inhibition
(rag/liter)
Source
Sodium 2,4,5-trichlorophenate
2,4, 5-Tr ichlorophenol
2,4, 6-Tr ichlorophenol
Sodium 2,3,4,6-tetrachlorophenate
2,3,4, 6-Tetrachlorophenol
Pentachlorophenol
Rhizopua nigriaana
Rhizoatonia aolani
Chaetomium globoeum
Hormiaaium gelatinoaum
Aepergillus No. 29
Polyporua tulipiferae
Aepergillua flavus
Lenzitea trabea
Ceratoatomella pilifera
Triohophyton interdigitale
Trichophyton roaaaeum
Aapergillus nigev
Aepepgillue niger
Peniaillium expansion
Rhizopua nigriaana
Rhizoatonia aolani
Chaetomium globosum
Hormiaaium gelatinoaum
Aapergillua No. 29
Polypoma tulipfevae
Aspevgillue flavue
Lenzitea tvabea
Ceratostomella pilifera
Triahophybon interdigitale
Trichophyton vosaaewn
Trichoderma vifide
Aapergillue nigev
Aepergillus nigev
Penioillium exponaum
Triohodevma viride
Trichoderma viride
Trichodevma sp.
Ceratooyatia pilifeva
Polypopus tulipifevae
Rhizopua etolonifer
Lenzitee tvabea
Ceratoayetia ipa
Chaetomium globoeian
Aapergillua niger
40-55
4-6
8-17
11-28
6-11
8-11
6-11
4-6
6-11
2-40
11-22
75
15
7
35-50
4-5
8-15
10-25
5-10
7-10
5-10
4-5
5-10
2-4
10-20
7a
310
20
30 a
0.8a
25-50
10-25
5-10
<1
1
1-2.5
10-25
1-2.5
10-25
Dow Chemical Company, 1969a
Dow Chemical Company, 1969a
Dow Chemical Company, 1969a
Dow Chemical Company, 1969
Dow Chemical Company, 1969i
Dow Chemical Company, 1969i>
Dow Chemical Company, 1969b
Dow Chemical Company, 1969b
Dow Chemical Company, 19692)
Dow Chemical Company, 1969i>
Dow Chemical Company, 1969i>
Dow Chemical Company, 1969b
Dow Chemical Company, 1969i>
Dow Chemical Company, 1969i
Blackmail, Parke, and Carton, 1955
Mason, Brown, and Minga, 1951
Walko, 1972
Walko, 1972
Blackman, Parke, and Carton, 1955
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
Dow Chemical Company, undated
?Value for 50% inhibition of growth.
Dow Chemical Company purified grade, proprietary name Dowicide EC-7.
-------
15
TABLE A.3.4.
EFFECT OF CHLOROPHENOLS ON CHLOROPHYLL SYNTHESIS BY
CHLORELLA PYRENOIDOSA
Compound
2-Chlorophenol
3-Chlorophenol
4-Chlorophenol
2 , 4-Dichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
Pentachlorophenol
Concentration
(rag/liter)
Control
10
50
100
250
500
Control
10
50
100
250
500
Control
10
50
100
250
500
Control
1
10
25
50
100
Control
1.0
2.5
5.0
7.5
10.0
Control
1.0
2.5
5.0
7.5
10.0
Control
0.0008
0.0015
0.0038
0.0075
Chlorophyll (mg/ liter)
After
0 day
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
9.6
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
10.4
9.7
9.7
9.7
9.7
9.7
After
1 day
24.8
25.6
16.8
10.4
9.6
6.4
24.8
24.8
18.4
10.0
6.0
0
24.8
24.6
20.0
11.6
6.8
2.0
24.8
25.6
12.8
9.6
8.0
5.0
24.8
20.0
16.0
12.2
8.8
6.2
24.8
24.8
18.4
15.6
11.6
8.8
26.4
11.6
7.0
4.6
2.4
After
2 days
74.6
76.8
40.0
28.0
8.4
2.4
74.6
76.0
22.8
9.4
3.2
0
74.6
75.6
25.2
12.8
4.4
0
77.0
46.8
36.6
15.6
11.6
1.6
77.0
52.8
18.4
9.6
6.2
1.6
77.0
74.4
26.0
12.8
7.2
4.4
77.6
23.6
7.0
5.2
0
After
3 days
66.8
64.8
52.0
44.0
8.0
1.2
66.8
64.8
32.0
8.4
1.2
0
66.8
66.8
36.0
13.6
2.0
0
64.8
60.0
50.2
24.0
12.8
0
65.8
56.8
26.4
8.0
2.4
0
64.8
58.4
32.0
9.6
4.4
0
68.8
44.4
20.0
6.8
0
Source: Adapted from Huang and Gloyna, 1967, Table 3-9, p. 56, and
Table 3-10, p. 61.
-------
TABLE A.3.5.
16
TOXICITY CONSTANTS OF CHLOROPHENOLS TO
CHLORELLA PYRENOIDOSA
Organic
compound
Phenol
2-Bromophenol
3-Bromophenol
4-Bromophenol
2-Chlorophenol
3-Chlorophenol
4-Chlorophenol
2 , 4-Dichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
Pentachlorophenol
Toxicity
constant
(x 10-3)
2.99
8.88
20.53
18.75
7.18
18.12
15.28
32.70
472.00
412.00
656,000.00
Phenol
coefficient
1.00
2.97
6.85
6.28
2.40
6.06
5.11
10.90
158.00
138.00
222,000.00
Concentration
tested showing
no toxicity
(mg/liter)
10.0
10.0
10.0
10.0
10.0
10.0
1.0
1.0
1.0
Source: Compiled from Huang and Gloyna, 1967.
pentachlorophenol inhibited chlorophyll synthesis for two days. Penta-
chlorophenol and sodium pentachlorophenate are effective algicides and
have been used commercially for this purpose. The potential for serious
effects on waste stabilization ponds (where the healthy growth of algae
is important in waste treatment) may be jeopardized by the presence of
higher chlorophenols (trichlorophenols and pentachlorophenol). Tetra-
chlorophenols have not been tested for their effect on algae, but their
toxicity may be similar to that of pentachlorophenol.
-------
17
SECTION A.3
REFERENCES
1. Baker, J. W., I. Schumacher, and D. P. Roman. 1970. Antiseptics
and Disinfectants. In: Medicinal Chemistry, Part I, 4th ed., A.
Burger, ed. John Wiley and Sons, Interscience Publishers, New York.
pp. 627-661.
2. Blackman, G. E., M. H. Parke, and G. Carton. 1955. The Physiological
Activity of Substituted Phenols: I. Relationships between Chemical
Structure and Physiological Activity. Arch. Biochem. Biophys.
54:45-54.
3. Dow Chemical Company. 1969a. Hazards Due to Toxicity and Precautions
for Safe Handling and Use. In: Antimicrobial Agents, Section 1-10,
Dowicide B Antimicrobial. Midland, Mich. 3 pp.
4. Dow Chemical Company. 19692?. Hazards Due to Toxicity and Precautions
for Safe Handling and Use. In: Antimicrobial Agents, Section 1-2,
Dowicide 2 Antimicrobial. Midland, Mich. 3 pp.
5. Dow Chemical Company. Undated. Dowicide EC-7 Antimicrobial. Midland,
Mich. 3 pp.
6. Huang, J. C., and E. F. Gloyna. 1967. Effects of Toxic Organics on
Photosynthetic Reoxygenation. University of Texas, Center for Research
in Water Resources, Austin. 163 pp.
7. Mason, C. T., R. W. Brown, and A. E. Minga. 1951. The Relationship
between Fungicidal Activity and Chemical Constitution. Phytopathology
41:164-171.
8. Sykes, G. 1965. Phenols, Soaps, Alcohols and Related Compounds. In:
Disinfection and Sterilization, 2nd ed. E. and F. N. Spon Ltd.,
London, pp. 311-349.
9. Walko, J. F. 1972. Controlling Biological Fouling in Cooling Systems -
Part II. Chem. Eng. (N.Y.) 79:104.
-------
A.4 BIOLOGICAL ASPECTS IN PLANTS
A.4.1 METABOLISM
A.4.1.1 Uptake and Absorption
Data on the uptake and absorption of chlorophenols by vascular plants
are scant. 2,4-Dichlorophenol is rapidly absorbed by the roots of oats
and soybeans grown in nutrient solution or soil containing 2,4-dichloro-
phenol. More 2,4-dichlorophenol is absorbed when the plants are grown in
nutrient solution than in soil; absorption depends on such factors as
plant species, age, growth, and media composition. Pentachlorophenol is
absorbed readily by vascular plants. The compound is absorbed following
foliar application to sugar cane and cotton plants, and rapid absorption
by the roots occurs in sugar cane grown in nutrient solutions containing
pentachlorophenol. Data on other chlorophenols are not available.
A.4.1.2 Transport and Distribution
Small, detectable quantities of 2,4-dichlorophenol are transported
to shoots of oats and soybeans following root absorption from nutrient
solutions or soils. The substance is not translocated to the grain of
oat plants; however, small quantities are found in soybean seeds follow-
ing absorption. Oats appear capable of concentrating 2,4-dichlorophenol
from nutrient solution by a factor of 9; however, no concentration effect
is seen when oats are grown in soil containing 2,4-dichlorophenol, nor is
concentration seen when soybeans are grown in nutrient solution or soil.
2,4-Dichlorophenol appears to be relatively immobile following foliar
application to soybeans.
Transport of pentachlorophenol in vascular plants depends on species
characteristics. Very little pentachlorophenol is transported in sugar
cane grown in nutrient solution containing pentachlorophenol, although
a small quantity of the substance is found in the stalks and suckers.
Similarly, pentachlorophenol remains at the site of foliar application
in sugar cane until the leaves abscise and the compound is lost from
the plant. Conversely, some pentachlorophenol is translocated in cotton
plants. Detectable levels of pentachlorophenol were found in cotton seed
kernels of bolls which were closed at the time the plants were sprayed
with a solution containing pentachlorophenol, indicating translocation
from the exterior of the bolls to the kernels. Furthermore, some penta-
chlorophenol translocation occurred within cotton seedlings following
foliar application.
Based on the available data, contamination of food crops with chloro-
phenols present in soil is not likely. Absorption by roots, on the other
hand, may pose a problem in the cultivation of roots and tubers in soils
contaminated with chlorophenols. Furthermore, limited data indicate that
pentachlorophenol may be transported within cotton plants following foliar
application.
18
-------
19
A.4.1.3 Biotransformation
Plants are capable of metabolizing a number of chlorophenols. Glyco-
side formation (conjugation) and subsequent immobilization of 2-chloro-
phenol has been demonstrated in the roots of tomato plants grown in sand
cultures containing the compound. The further fate of the conjugate
identified as 3-0-chlorophenyl gentiobioside is not known.
Glycoside formation and Immobilization of 2,4-dichlorophenol in
strawberry leaves has also been reported. The appearance and subsequent
dissipation of 2,4-dichlorophenol from rice plants and soils following
application of the herbicide dichlorophenoxyacetic acid (2,4-D) has been
demonstrated. As the plants matured, 2,4-dichlorophenol residues declined
in the plants, and no 2,4-dichlorophenol was detected at maturity. The
metabolic fate of the compound is not known.
Both free 2,3,4,6-tetrachlorophenol and unidentified tetrachloro-
phenol conjugates have been reported in lettuce plants following treatment
with lindane.
The metabolism of pentachlorophenol in sugar cane roots has been
demonstrated, but it is not known whether conjugation or another mechanism
is responsible for the degradation. Based on evidence presented for other
chlorophenols, conjugate formation of pentachlorophenol may occur in
vascular plants, but the pathways responsible for further metabolism have
not been elucidated.
A.4.1.4 Elimination
Chlorophenols may be dissipated from plants in four ways: (1) vola-
tilization from leaf surfaces or stems, (2) metabolism with subsequent
excretion of metabolites, (3) excretion through the roots, and (4) loss
through abscission of leaves and other plant parts.
The substantial vapor pressure of chlorophenols indicates that vola-
tilization provides a route of elimination from vascular plants. Vola-
tilization has been proposed as a mechanism for the elimination of
2,4-dichlorophenol from soybean plants receiving foliar applications and
for the loss of pentachlorophenol following application to sugar cane.
Excretion of the herbicide 2,4-D through the roots of vascular plants
has been demonstrated, and it is proposed that 2,4-dichlorophenol (a major
metabolite of the herbicide) may also be excreted in this manner. Excre-
tion of pentachlorophenol from the roots of sugar cane following absorp-
tion has also been shown.
Chlorophenols present in vascular plants may also be eliminated by
abscission of leaves and other plant parts if the compound is not trans-
ported or removed rapidly from the plant in other ways. Data indicate
that chlorophenols are relatively immobile compounds and that elimination
by this mechanism may be important.
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20
A, 4.2 EFFECTS
A.4.2.1 Physiological or Biochemical Role
No physiological or biochemical requirement for chlorophenols by
vascular plants has been documented.
A.4.2.2 Toxicity
A.4.2.2.1 Mechanisms of Action — The mechanism of the phytotoxic
action of chlorophenols is not well understood. Both 2-chlorophenol and
2,4-dichlorophenol are capable of inhibiting the enzyme catalase. The
contribution of this enzymatic effect to the phytotoxicity of chloro-
phenols is not known. Pentachlorophenol is capable of uncoupling oxida-
tive phosphorylation in both plants and animals. This mechanism appears
to be the most likely explanation for the clearly demonstrable toxicity
of pentachlorophenol. It seems likely — based on evidence with other
organisms — that other chlorophenols (particularly the tetrachlorophenols)
share this property with pentachlorophenol.
A.4.2.2.2 General Toxicity — No documented cases of 2-chlorophenol
phytotoxicity were found in the literature. Only one report documented
the phytotoxicity of 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-
trichlorophenol, and 2,3,4,6-tetrachlorophenol. The concentrations of
these compounds required to obtain 50% mortality in the aquatic plant
Lemna minor are given in Table A.4.1. Increasing chlorine substitution
appears to enhance toxicity. The data in Table A.4.1 have been corrected
for disassociation effects at the experimental pH of 5.1. Logarithms of
these data were plotted against the logarithms of the solubility of chlo-
rophenols (Figure A.4.1); the linear relationship indicates that the phys-
iological effect (toxicity) is increased as the pH of the medium approaches
TABLE A.4.1. CONCENTRATION OF CHLOROPHENOLS NECESSARY
FOR 50% MORTALITY OF LEMNA MINOR
Concentration
Compound
(moles/liter) (mg/liter)
Phenol
4-Chlorophenol
2 , 4-Dichlorophenol
2,4, 6-Trichlorophenol
2,4, 5-Trichlorophenol
2,3,4, 6-Tetrachlorophenol
Pentachlorophenol
1.6 x 10-2
2.2 x 1(T3
3.6 x 10-"
3.0 x 10-s
8.4 x 10-°
2.6 x 10-°
7.1 x 10~7
1500
283
59
6.0
1.7
0.61
0.19
Source: Adapted from Blackman, Parke, and Carton,
1955a, Table I, p. 50. Reprinted by permission of the
publisher.
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21
-2
ORNL-OWG 78-10496
-3
o
in
0
-4
-5
4-CHLOROPHENOL,*
2,4-DICHLOROPHENOL
• / 2,4,6-TRICHLOROPHENOL
• ~
2,4,5-TRICHLOROPHENOL
2,3,4,6-TETRACHLOROPHENOL
PENTACHLOROPHENOL
I I
-2
LOG SOLUBILITY
Figure A.4.1. Relationship between the logarithms of the solubili-
ties of chlorophenols and the logarithms of the LDSo in Lernna minor.
Source: Adapted from Blackman, Parke, and Carton, 19552?, Figure 2, p. 63.
Reprinted by permission of the publisher.
the pK of the chlorophenol. It is evident that pH is of major importance
in assessing chlorophenol toxicity to aquatic plants. No other informa-
tion on the phytotoxic effects of the lower chlorophenols is available.
However, pentachlorophenol is clearly phytotoxic and has been used as a
herbicide. Deaths of terrestrial plants grown in pentachlorophenol-
treated containers or near pentachlorophenol-treated fence posts have
been reported. When direct plant contact with pentachlorophenol was not
evident, pentachlorophenol in the air was thought to be responsible for
plant injury. Pentachlorophenol also has been used as an effective
general herbicide, and caution must be exercised when the compound is
used in proximity to crops. Pentachlorophenol was the most toxic of the
chlorophenols when tested with the aquatic plant Lenma minor (Table
A.4.1, Figure A.4.1), and contamination of waterways with pentachloro-
phenols poses a potentially serious hazard to aquatic flora.
A.4.2.2.3 Mitotic Effects — Several chlorophenols affect mitosis
in vascular plants. 2,4-Dichlorophenol treatment of the European broad
bean (Vieia faba) caused an increased frequency of mitotic anomalies in
pollen mother cells. This effect depended on plant age, but decreased
plant yield was noted through the second generation. 2,4,5-Trichloro-
phenol did not affect the frequency of mitotic anomalies when tested in
the same system.
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22
Pentachlorophenol is also capable of increasing the number of
mitotic abnormalities in plants treated with the compound. A positive
effect of pentachlorophenol on the number of mitotic anomalies, a
considerable decrease in the mitotic index of a root preparation of
Vieia faba, and an increase in the number of mitotic abnormalities in
a root tip preparation of water hyacinth (Eichhornia arassipes) have
been reported. Other chlorophenols have not been tested for the presence
or absence of this effect.
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23
SECTION A.4
REFERENCES
1. Blackman, G. E., M. H. Parke, and G. Carton. 1955a. The Physio-
logical Activity of Substituted Phenols: I. Relationships between
Chemical Structure and Physiological Activity. Arch. Biochem.
Biophys. 54:45-54.
2. Blackman, G. E., M. H. Parke, and G. Carton. 1955&. The Physio-
logical Activity of Substituted Phenols: II. Relationships between
Physical Properties and Physiological Activity. Arch. Biochem.
Biophys. 54:55-71.
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A.5 BIOLOGICAL ASPECTS IN WILD AND DOMESTIC ANIMALS
A.5.1 BIOLOGICAL ASPECTS IN BIRDS AND MAMMALS
A.5.1.1 Metabolism
A.5.1.1.1 Uptake and Absorption — No information is available on
the direct absorption of lower chlorophenols by birds or domestic mam-
mals. Ample evidence exists, however, that pentachlorophenol is absorbed
by inhalation, through the skin, or following ingestion and that it pro-
duces toxic symptoms. It is speculated that tetrachlorophenols share
similar properties with pentachlorophenol because their chemical struc-
tures are similar and the mechanisms of their toxicity appear similar,
but no definitive data are available. The possible routes of uptake of
lower chlorophenols are speculative.
A.5.1.1.2 Transport and Distribution — Following entry into the
body, chlorophenols are transported mainly by the blood. Pentachloro-
phenol is known to be transported by this route, but direct data on the
mode of transport of other chlorophenols in domestic mammals and birds
are not available.
Data on the tissue distribution of chlorophenols in birds and mam-
mals are sketchy. Most data on lower chlorophenols are derived from
experiments tracing the metabolic fate of pesticides in the organisms.
Many pesticides and commonly used organic chemicals produce chlorophenols
as metabolites. The applicability of tissue distribution data following
administration of precursor compounds as opposed to direct administration
of a chlorophenol is not understood. However, indirect information sheds
some light on tissue distribution. 2,4-Dichlorophenol has been detected
in the liver and kidneys of sheep and cattle following dichlorophenoxy-
acetic acid (2,4-D) administration, but none was found in the muscles or
fat. 2,4-Dichlorophenol was detected in liver tissue and egg yolk from
chickens dosed with nemacide [0-(2,4-dichlorophenyl)0,0-diethyl phos-
phorothioate] but was not found in muscle or fat. Following administra-
tion of high doses of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) to cows,
2,4,5-trichlorophenol was detected in milk and cream from the animals.
Tissue levels of 2,4,5-trichlorophenol were not determined. High levels
of pentachlorophenol were found in the kidneys of swine fed pentachloro-
phenol, but very little was found in fat, liver, or muscle.
Much of the available information on the transport and distribution
of chlorophenols has been derived from experiments conducted with labora-
tory animals. This information is summarized primarily in Section A.6.1.2;
the reader is referred to that section for information obtained by extrap-
olating from laboratory animals to domestic animals and wildlife.
A.5.1.1.3 Biotransformation — Information on the metabolism of
chlorophenols is mainly derived from experimental animals (Section
A.6.1.3).
24
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25
A.5.1.1.4 Elimination — No information on the elimination of lower
chlorophenols from domestic animals or wildlife is available. It seems
likely that chlorophenols are excreted primarily in the urine. Penta-
chlorophenol is rapidly excreted in the urine, but some residues have
been detected in the feces of sheep and cattle following administration
of the compound. Pentachlorophenol is the most lipophilic of the com-
pounds examined in this report. Since elimination of pentachlorophenol
from the body occurs rapidly through the urine, the more soluble, less
lipophilic, lower chlorophenols would probably be excreted even more
rapidly.
A.5.1.2 Effects
A.5.1.2.1 Physiological or Biochemical Role — No evidence indicates
that any chlorophenols play a physiological or biochemical role in domes-
tic animals or birds, and it is unlikely that any nutritional require-
ments for the compounds exist.
A.5.1.2.2 Toxicity — Of all chlorophenols, only pentachlorophenol
has a documented toxic effect on domestic animals and wildlife. 2,4,5-
Trichlorophenol was fed to cattle at levels up to 159 mg/kg body weight
for 78 days, and no effect on the animals was noted at any dose level.
The toxicity of pentachlorophenol to many animals — including swine,
cattle, sheep, cats, rabbits, and other laboratory animals — is well doc-
umented. Both local effects (irritation and necrosis of the skin) and
systemic effects, including death, have been reported. Constant direct
cutaneous exposure to pentachlorophenol-treated wood has caused mortality
in swine. However, present evidence does not indicate a direct hazard to
domestic or wild animals from pentachlorophenol-treated wood unless they
are in constant contact with the wood. Nonetheless, more information is
needed to demonstrate whether chronic exposure to low levels of pentachlo-
rophenol poses a subtle hazard to the. health of domestic and wild animals.
Levels of pentachlorophenol in the tissues of domestic animals exposed to
pentachlorophenol rarely have been documented. Humans would be exposed
to pentachlorophenol if meat were contaminated; therefore, further research
in this area is highly recommended. Another hazard may be posed by the
use of pentachlorophenol as a herbicide or molluscicide. Extensive losses
of wildlife, including fish, frogs, snails, and birds, were attributed to
molluscicidal application of pentachlorophenol in Surinam. Sublethal lev-
els of the compound were also detected in animals which were not killed;
the effect of these levels is not known. Chlorophenols other than penta-
chlorophenol are not used directly as herbicides and their use as preserv-
atives is limited.
Anisoles — metabolites of chlorophenols — are responsible for the
presence of a musty taint occasionally associated with broiler chickens.
2,4,6-Trichloroanisole, 2,3,4,6-tetrachloroanisole, and pentachloroanisole,
which are formed from the corresponding chlorophenols in poultry litter,
are responsible for this phenomenon. Because tainted chickens are unap-
petizing, the hazards to humans that may be associated with ingestion of
the anisoles are minimized, and the problem becomes primarily an economic
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26
issue. Rearing chickens on litter which does not contain chlorophenols
or removal of chickens from tainted litter several weeks prior to slaugh-
ter usually resolves the problem. The question of whether or not chloro-
phenols are absorbed directly by the chickens along with the anisoles
warrants further research.
A.5.2 BIOLOGICAL ASPECTS IN FISH AND OTHER AQUATIC ORGANISMS
Data on the metabolism of lower chlorophenols and their effects on
aquatic organisms are extremely scarce. The toxic levels of these com-
pounds for various aquatic organisms are available, but the great bulk of
information relates to pentachlorophenol. Information on the metabolism
and toxicity of pentachlorophenol to aquatic organisms found in Section
D.5.2 will not be duplicated in this section; only a brief overview is
presented below.
A.5.2.1 Metabolism
A.5.2.1.1 Uptake and Absorption — Uptake of chlorophenols by aquatic
organisms can be inferred from the documented toxicity of these compounds
(Section A.5.2.2). Fish and other aquatic organisms absorb chlorophenols
through the gills, the gastrointestinal tract, or directly through the
body surfaces. Most available toxicity data do not deal with the route
of uptake of the compound, and rates of chlorophenol uptake are frequently
speculative. No direct data on the route or rates of uptake of lower
chlorophenols by aquatic organisms were found. Pentachlorophenol is rap-
idly removed from the surrounding water by the rainbow trout, short-necked
clam, eel, and goldfish. This rapid uptake is followed by excretion of
pentachlorophenol, detoxification of pentachlorophenol by conjugation,
subsequent excretion of the detoxified conjugate, and accumulation, par-
ticularly in the fat of the eel.
A.5.2.1.2 Transport and Distribution — Transport and distribution
of lower chlorophenols following absorption by aquatic organisms have
not been studied. However, considerable evidence on the transport and
distribution of pentachlorophenol in aquatic organisms is available.
Following absorption of pentachlorophenol by the short-necked clam, high
levels of the compound appear in the bojanus1 organ, the liver, and the
digestive tract. Pentachlorophenol appears to be transported primarily
by the blood in aquatic organisms. High levels of pentachlorophenol were
detected in the liver and muscle of eels dosed with the compound. Gold-
fish accumulate large quantities of pentachlorophenol in the gallbladder,
and measurable amounts are also detected in the gills, kidney, and
hepatopancreas.
A.5.2.1.3 Biotransformation — No information on the metabolism of
lower chlorophenols in aquatic organisms is available. Pentachloro-
phenol appears to be detoxified by the short-necked clam and the gold-
fish; detoxification is accomplished by a similar mechanism in both
cases. Sulfate conjugation and subsequent excretion have been demon-
strated following uptake of pentachlorophenol by these organisms. It
has been suggested that pentachlorophenol is detoxified in fish follow-
ing transfer to the hepatopancreas and that the metabolites, in part,
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27
are transported to the gallbladder and bile. The extent to which con-
jugate formation occurs as a detoxification mechanism in other aquatic
organisms is not known.
A.5.2.1.4 Elimination — Routes and rates of elimination of lower
chlorophenols from aquatic organisms are not known. Pentachlorophenol
is excreted as a sulfate ester from the short-necked clam and the gold-
fish following uptake. There are apparently at least two rates of ex-
cretion by goldfish. Pentachlorophenol excretion is initially rapid;
approximately 80% of the pentachlorophenol content of the fish is excreted
within 20 hr. Excretion of the remaining 20% is much slower. The hepa-
topancreas and the gallbladder are believed to play important roles in
the excretion of pentachlorophenol by goldfish; the slow excretion seen
after the initial rapid excretion stage may result partially from the
storage of the compound in the gallbladder. The gallbladder may also
play an important role in the excretion of pentachlorophenol by mammals.
A.5.2.2 Effects
A.5.2.2.1 Physiological or Biochemical Role — No evidence indicates
that any chlorophenols play a physiological or biochemical role in aquatic
organisms, and it is unlikely that any nutritional requirement for the
compounds exists.
A.5.2.2.2 Toxicity
A.5.2.2.2.1 Mechanism of action — The mechanism of toxic action of
chlorophenols on aquatic organisms is not well understood. 2-Chlorophenol
inhibits oxygen uptake in in vitro systems utilizing various fish tissue
preparations, but the contribution of this effect to the toxicity of 2-
chlorophenol in intact organisms is unknown. The biochemical mechanism
of pentachlorophenol toxicity probably derives from its ability to uncouple
oxidative phosphorylation and, at higher concentrations, to inactivate
glycolytic enzymes. This effect has been well documented in experimental
mammals, and it is believed that the same effect is responsible for the
toxic action of the compound in aquatic organisms.
A.5.2.2.2.2 Acute toxicity — Information on the toxicity of lower
chlorophenols to aquatic organisms is limited. Dosages and effects on
various aquatic organisms are presented in Table A.5.1. Toxicity data
on 2,4,5-trichlorophenol and the tetrachlorophenols were not found. The
acute toxicity of pentachlorophenol to aquatic organisms has been well
studied; a few typical values are listed in Table A.5.1. The reader is
referred to Section D.5.2.2.2 for data on toxicity of pentachlorophenol
to a large number of fish and invertebrate species. Although it is
difficult to draw conclusions from the limited data in Table A.5.1, the
toxicity of chlorophenols to aquatic organisms likely increases with in-
creasing chlorination of the parent phenol. Pentachlorophenol is by far
the most toxic compound for which data are available. Fish kills have
been reported when pentachlorophenol reaches waterways either from penta-
chlorophenol-contaminated effluents, spillage of the concentrated com-
pound, or herbicide use. Pentachlorophenol concentrations resulting in
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TABLE A.5.1. TOXIC!TY OF CHLOROPHENOLS TO AQUATIC ORGANISMS
Compound
2-Chlorophenol
2,4-Dichlorophenol
Test organism
Bluegill
(Lepomis maaroahirua )
Rainbow trout
(Salmo jairdnei'ii )
Daphniii majm
Fertilized sea urchin eggs
Level of
chlorophenol
(mg/liter)
8.1
2.7
7.4
10.3
48-hr TL,,/'
48-hr TLW
48-hr Tlw
Decreased rate of
Source
Lammering and
Burbank, 1960
Slettcn and
Burbank, 1972
Kopperman, Carlson,
and Caple, 1974
Clowes, 1951
2,4,6-Trichlorophenol
Pentachlorophenol
t tia puna tula ta)
Daphni
Goodnight, 1942
Goodnight, 1942
NJ
00
— Median tolerance limit.
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29
50% mortality of fish depend on the species and range from a low of 30
lag/liter for the bluegill to as high as 460 yg/liter for the channel cat-
fish and 600 yg/liter for the top minnow (Fundulus notatus). Some aqua-
tic invertebrates, including several species of commercial shellfish, are
as sensitive to pentachlorophenol as fish. On the other hand, many aqua-
tic invertebrates can survive concentrations as high as 5 to 10 mg/liter
with no apparent toxic effects. Of all chlorophenols, pentachlorophenol
clearly poses the greatest potential hazard to aquatic flora and fauna.
A.5.2.2.2.3 Chronic toxicity — The lethal dose values in Table
A.5.1 are at best a poor indication of the true environmental signifi-
cance of chlorophenols. Although dramatic effects such as massive fish
kills are seen readily and are aesthetically objectionable, more subtle
effects may occur in aquatic communities exposed to chlorophenols. Such
effects may decrease the ability of some species to reproduce, thereby
affecting the survival of a species or perhaps the survival and integrity
of entire biological communities. Data addressing the chronic or sub-
lethal effects of lower chlorophenols are scant. 2,4-Dichlorophenol and
2,4,6-trichlorophenol adversely affected the development of fertilized
sea urchin eggs at concentrations of 10.3 mg/liter and 6.2 mg/liter
respectively.
Data suggest that sublethal levels of pentachlorophenol subtly
affect aquatic organisms. Pentachlorophenol is lethal to developing
trout embryos and alevins at a concentration of 40 yg/liter. Decreased
growth and curtailment of food conversion efficiency in the sockeye sal-
mon reportedly occurs at pentachlorophenol levels of less than 2 yg/liter.
Other more serious effects, including renal degeneration, liver damage,
and retarded gonadal development, may occur at higher concentrations
(500 yg/liter). A large number of metabolic parameters, including the
activity of a number of liver enzymes, were affected in eels exposed to
100 yg/liter pentachlorophenol. Other reports indicated severe devel-
opmental abnormalities in a number of fish species at pentachlorophenol
concentrations greater than 1 mg/liter. It has been suggested that the
maximum permissible concentration of pentachlorophenol in water should
be 0.1 mg/liter. In view of the adverse effects seen at concentrations
as low as 2 yg/liter, this maximum concentration seems far too high.
The seriousness of the potential problem is emphasized by data which
indicate that pentachlorophenol may bioaccumlate in aquatic organisms
living in pentachlorophenol-contaminated water and in other organisms
which may be exposed to the compound through food chain interactions.
Due to a lack of information, the hazard to aquatic organisms posed by
lower chlorophenols cannot be assessed.
A.5.2.2.2.4 Effect of environmental parameters on toxicity — Pub-
lished toxicity values are valid only for the specific conditions used
by individual investigators. Differing environmental conditions can
affect the toxicity of chlorophenols to aquatic organisms. For example,
the toxicity of pentachlorophenol to aquatic animals is enhanced by de-
creases in pH and dissolved oxygen content. Pentachlorophenol toxicity
is also enhanced by an increase in temperature. The effects of these
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30
factors, as well as others which have not been examined, on pentachloro-
phenol toxicity must be assessed on an individual basis. Another poten-
tial hazard in interpreting chlorophenol toxicity is the possible presence
of other pollutants — either natural or man-made. Other compounds may
either enhance or decrease the toxicity of individual chlorophenols;
these synergistic effects in the aquatic environment are poorly understood.
A.5.2.2.2.5 Bioconcentration and biomagnification in aquatic
organisms — It is not known whether biomagnification either from the
surrounding water or from food chain interactions occurs with any lower
chlorophenols. Evidence exists that these processes occur when penta-
chlorophenol is present in the water. Pentachlorophenol levels in fish
taken from a lake receiving discharges of pulp mill effluents were found
to be 100- to 1000-fold higher than pentachlorophenol levels in the lake
water. The eel, a species with a higher than normal fat content, concen-
trated pentachlorophenol to the greatest extent. In laboratory experi-
ments, pentachlorophenol levels in goldfish were found to be 1000-fold
higher than the concentration in the medium following an exposure time
of 120 hr. The high levels of pentachlorophenol found in goldfish pro-
bably resulted from direct absorption and biomagnification by the fish.
Other species of fish have been shown to concentrate pentachlorophenol,
but not to the same extent. High levels found in fish taken from a con-
taminated lake may have been caused by either direct absorption and con-
centration of the compound or by food chain biomagnification.
Biomagnification of pentachlorophenol in a simple laboratory six-
element food chain has been demonstrated. The model aquatic ecosystem
contained algae, snails, daphnia, mosquito larvae, and mosquito fish. At
the termination of the experiment the organisms contained higher concen-
trations of pentachlorophenol than did the medium. The ecological magni-
fication factors (defined as ratio of concentration of pentachlorophenol
in the organisms to concentration of pentachlorophenol in the water) for
these organisms were: algae, 1.58; mosquito larvae, 16; snail, 131;
daphnia, 165; and mosquito fish, 296. Although food chain biomagnifica-
tion is not shown conclusively by these data, a strong correlation between
the trophic status of the organisms and the ecological magnification fac-
tors is evident. Data relating to food chain biomagnification in the
environment are not available; however, the process may be responsible
for some of the high levels of pentachlorophenol detected in aquatic
organisms. Although pentachlorophenol is metabolized rapidly by many
aquatic organisms, the hazards posed to aquatic ecosystems and eventually
to humans must be carefully considered. Evidence exists that pentachloro-
phenol may persist in fish for as long as two months following exposure
to the compound and transfer to clean water. These levels, although low,
present the potential for chronic low-level exposure to humans.
The above experiment with the model aquatic ecosystem was also con-
ducted with a number of other commonly used organic compounds. Pentachlo-
rophenol was roughly intermediate among the compounds tested with respect
to ecological magnification value. For example, DDT was found to have an
ecological magnification factor of 17,000. Food chain hazards associated
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31
with DDT have been well documented; hazards posed by pentachlorophenol are
probably of a lower degree. Ecological magnification values for hexachlo-
rocyclohexane and chlorobenzene were 1166 and 650 respectively. These
values are of interest because pentachlorophenol may be formed following
metabolism of these compounds in higher organisms. For example, substan-
tial amounts of pentachlorophenol were formed by members of the model com-
munity as a metabolic breakdown product of hexachlorocyclohexane. Thus,
levels of pentachlorophenol in waterways may result in part from the
degradation of other compounds and, if pentachlorophenol does not reach
waterways directly, the compound may be produced by these metabolic proc-
esses. Thus, total elimination of pentachlorophenol from waterways may
be a formidable, if not impossible, task.
A.5.2.2.2.6 Detection and avoidance reactions — Fish are capable
of detecting pentachlorophenol and demonstrate an avoidance reaction to
the compound when placed in a pentachlorophenol gradient. Species differ-
ences play a major part in the pentachlorophenol level which can be dis-
criminated by fish. The usefulness of this mechanism to the individual
organism in avoiding areas of local pentachlorophenol toxicity is ques-
tionable because levels of pentachlorophenol which cause chronic toxicity
are in many cases below the detectable threshold discrimination of fish.
Furthermore, an avoidance reaction may have little usefulness when all
or a large portion of the environment of the fish is contaminated with
the compound. No evidence suggests that fish are capable of detecting
and avoiding other chlorophenols.
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32
SECTION A.5
REFERENCES
1. Clemens, H. P., and K. E. Sneed. 1959. Lethal Doses of Several
Commercial Chemicals for Fingerling Channel Catfish. U.S. Fish and
Wildlife Service Special Scientific Report — Fisheries No. 316.
U.S. Department of the Interior, Washington, D.C. 10 pp.
2. Clowes, G.H.A. 1951. The Inhibition of Cell Division by Substituted
Phenols with Special Reference to the Metabolism of Dividing Cells.
Ann. N.Y. Acad. Sci. 51:1409-1431.
3. Goodnight, C. J. 1942. Toxicity of Sodium Pentachlorophenate and
Pentachlorophenol to Fish. Ind. Eng. Chem. 34(7):868-872.
4. Inglis, A., and E. L. Davis. 1973. Effects of Water Hardness on
the Toxicity of Several Organic and Inorganic Herbicides to Fish.
U.S. Bureau of Sport Fisheries and Wildlife Technical Paper No. 67.
U.S. Department of the Interior, Washington, D.C. 22 pp.
5. Kopperman, H. L., R. M. Carlson, and R. Caple. 1974. Aqueous Chlor-
ination and Ozonation Studies: I. Structure-Toxicity Correlations
of Phenolic Compounds to Dapknia magna. Chem. Biol. Interact.
9(4):245-251.
6. Lammering, M. W., and N. C. Burbank, Jr. 1960. The Toxicity of
Phenol, o-Chlorophenol, and o-Nitrophenol to Bluegill Sunfish. Proc.
Ind. Waste Conf. 15:541-555.
7. Manufacturing Chemists Association. 1972. The Effect of Chlorina-
tion on Selected Organic Chemicals. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C. pp.
73-100.
8. Sletten, 0., and N. C. Burbank, Jr. 1972. A Respirometric Screening
Test for Toxic Substances. Eng. Bull. Purdue Univ. Eng. Ext. Ser.
141(1):24-32.
9. Tomiyama, T., and K. Kawabe. 1962. The Toxic Effect of Pentachloro-
phenate, a Herbicide, on Fishery Organisms in Coastal Waters: I.
The Effect on Certain Fishes and a Shrimp. Bull. Jpn. Soc. Sci.
Fish. 28(3):379-382.
10. Tomiyama, T., K. Kobayashi, and K. Kawabe. 1962a. The Toxic Effect
of Pentachlorophenate, a Herbicide, on Fishery Organisms in Coastal
Waters: II. The Effect of PGP on Conchocelis. Bull. Jpn. Soc. Sci.
Fish. 28(3):383-386.
11. Tomiyama, T., K. Kobayashi, and K. Kawabe. 19622). The Toxic Effect
of Pentachlorophenate, a Herbicide, on Fishery Organisms in Coastal
Waters: III. The Effect on Venerupis phCUppincanm. Bull. Jpn. Soc.
Sci. Fish. 28(4):417-421.
-------
A.6 BIOLOGICAL ASPECTS IN HUMANS
A.6.1 METABOLISM
A.6.1.1 Uptake and Absorption
Uptake and absorption data for chlorophenols is derived mainly from
experimental animals. Documented human systemic toxicity cases are only
available for pentachlorophenol. Absorption can occur via the oral,
cutaneous, or respiratory routes in humans. Information on absorption
mechanisms and rates for lower chlorophenols is not available. Table
A.6.1 summarizes information on the absorption of chlorophenols derived
primarily from toxicity data. Chlorophenol toxicity in experimental
animals has been demonstrated following parenteral injection with appro-
priately high doses; oral toxicity has also been demonstrated. Respira-
tory absorption has been shown only for pentachlorophenol. The effects
of cutaneous absorption depend on the degree of chlorination of the
phenol. 2-Chlorophenol is readily absorbed through the skin, but 2,4-
dichlorophenol is absorbed less rapidly. The 2,4,5- and 2,4,6-trichloro-
phenol isomers are not absorbed by the cutaneous route, at least in toxic
amounts, but 2,3,4,6-tetrachlorophenol and pentachlorophenol are absorbed
readily.
Some information on the uptake of pentachlorophenol by humans and
experimental animals is available. Systemic toxicity can result from
cutaneous or oral exposure to the compound. Some differences in the
relative toxicities of pentachlorophenol and sodium pentachlorophenate
are evident. Pentachlorophenol administered by the oral or cutaneous
route appears to be approximately twice as toxic as sodium pentachloro-
phenate. The toxicity of pentachlorophenol depends on the solvent in
which it is carried, but no explanation has been provided for this phenom-
enon. It seems likely that the absorption and/or toxicity of other
chlorophenols may depend on the solvent in which the compounds are dis-
solved prior to contact, but more information is needed.
A.6.1.2 Transport and Distribution
No information is available on the transport and distribution of
lower chlorophenols in humans and experimental animals. However, limited
information is available on the tissue distribution of some of the tri-
chlorophenol and tetrachlorophenol isomers in experimental animals follow-
ing administration of organochlorine precursor compounds which yield
chlorophenols as metabolites. The data are difficult to interpret because
distribution sites within the organism may depend on factors such as the
sites within the body where the chlorophenol is produced and perhaps the
site within the body where the precursor preferentially locates.
Sheep fed a diet containing the herbicide 2,4,5-trichlorophenoxy-
acetic acid (2,4,5-T) had residues of 2,4,5-trichlorophenol in liver,
kidney, and muscle tissues but not in fat. When the diets containing
2,4,5-T were withdrawn one week prior to slaughter, 2,4,5-trichlorophenol
33
-------
TABLE A.6.1. ABSORPTION OF CHLOROPHENOLS BY HUMANS AND EXPERIMENTAL ANIMALS
Compound
2-Chlorophenol
2 , 4-Dichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2,3,4, 6-Tetrachlorophenol
2,3,5, 6-Tetrachlorophenol
Pentachlorophenol
Route of administration
Oral
Yes
Yes
Yes
Yes
Yes
Yesa
Cutaneous
Yes
Probably
No
No
Yes
Yes*
Respiratory Subcutaneous
Yes
Yes
Yes
Yes
Yesa Yes
Intraperitoneal
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Intravenous
Yes
Yes
Determined from human data.
-------
35
levels in muscle decreased, but liver and kidney tissues retained most of
the accumulated 2,4,5-trichlorophenol. When rats were dosed with lindane
for 19 consecutive days, 2,4,6-trichlorophenol and 2,3,4,6-tetrachloro-
phenol were found in the heart. The liver contained detectable levels of
2,3,4,6- and 2,3,5,6-tetrachlorophenol, and the kidneys contained 2,4,6-
trichlorophenol and both tetrachlorophenols. Available data indicate
that urine is the primary route of elimination. In view of the known
detoxification role of the liver, it is not surprising to find chloro-
phenol residues in this organ. If extrapolation from pentachlorophenol
data is valid, chlorophenols are likely transported in the blood. Whether
pentachlorophenol is absorbed through the skin, via the respiratory tract,
or through injection, it is distributed by the blood. Substantial data
have shown the presence of pentachlorophenol in the blood following up-
take by each of these routes. In addition, autopsy reports on victims
poisoned by pentachlorophenol show the presence of pentachlorophenol in.
the blood. Pentachlorophenol apparently does not bind to blood cells,
but evidence suggests binding to plasma protein. This binding may
account for the slower rate of pentachlorophenol loss in the later stages
of excretion.
Data for tissue distribution following uptake of pentachlorophenol
by humans is derived mainly from autopsy results of fatal cases of penta-
chlorophenol intoxication. These cases have consistently revealed the
presence of the compound in the liver, kidney, and usually the stomach.
Detectable residues also are occasionally seen in the brain, adrenal
glands, heart, lungs, and connective tissue. A recent survey indicated
that parts-per-billion levels of pentachlorophenol were present in adipose
tissue samples taken from the general population. The definitive kinetics
of pentachlorophenol accumulation in fat are unknown and are worthy of
further investigation.
The postmortem findings in humans poisoned by pentachlorophenol are
similar to findings in experimental animals. Pentachlorophenol appears
in most tissues (including stomach, intestines, kidney, liver, and gall-
bladder) of rabbits, mice, and rats dosed by the cutaneous, oral, or
intraperitoneal routes. A scheme for pentachlorophenol transport and
distribution in mammals is presented in Section D.6.1.2. Transfer of
pentachlorophenol across the placenta requires more study.
A.6.1.3 Biotransformation
Metabolic alteration of chlorophenols in mammals has been studied in
experimental animals, and data on the metabolic alterations of pentachloro-
phenol in humans have recently been reported. Very little information on
the metabolism of lower chlorophenols following uptake by mammals is
available. The metabolic fate of the chlorophenols formed from other
organochlorine compounds in the body may reflect the fate of chlorophenols
administered directly to animals. Data on chlorophenol metabolism in
higher animals indicate that conjugation is a major metabolic route.
Conjugation to sulfuric and glucuronic acids has been demonstrated for
chlorophenols following direct administration and following the produc-
tion of chlorophenols from precursor compounds.
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36
2-Chlorophenol was excreted in the urine of dogs in free and con-
jugated forms. Following administration, 87% of the compound was ex-
creted in the form of sulfuric and glucuronic acid conjugates. Free
2-chlorophenol as well as conjugates of sulfuric and glucuronic acids
have been detected in rabbits given chlorobenzene. Some investigators
have suggested that ortho methylation may be another route for 2-chloro-
phenol detoxification in mammals, but data are not available. 2,4-
Dichlorophenol was produced in mice following administration of 3- or
y-hexachlorocyclohexane. 2,4-Dichlorophenol was excreted in the free
state as well as in the form of sulfate and glucuronide conjugates;
other metabolites included 2,4,6-trichlorophenol and its sulfate and
glucuronide conjugates and trace amounts of 2,4,5-trichlorophenol and
its conjugates. Rats excreted 2,4,5-trichlorophenol and 2,4,5-trichloro-
phenol conjugates after administration of 4-(2,4,5-trichlorophenoxy)-
butyric acid. The 2,3,4,5-, 2,3,4,6-, and 2,3,5,6-tetrachlorophenol
isomers and their glucuronide conjugates were detected in urine from rats
dosed with pentachlorophenol. Data on other metabolic pathways for lower
chlorophenols are not available, although conjugation is a major metabolic
fate of these compounds in some experimental animals.
More data are available on the metabolic fate of pentachlorophenol
in experimental mammals. Conjugate formation occurs frequently with
pentachlorophenol. The formation of pentachlorphenyl-3-glucuronide has
been reported in rabbits. The production of tetrachlorohydroquinone and
its conjugates has been verified in mice and rats following pentachloro-
phenol administration. Furthermore, chloranil, a compound closely related
to tetrachlorohydroquinone, has been reported as a constituent of rabbit
urine following administration of pentachlorophenol. A proposed meta-
bolic pathway for pentachlorophenol in mammals has been constructed based
on available data (Section D.6.1.3). Because urinary levels of penta-
chlorophenol have been used to estimate pentachlorophenol exposure in
humans, a true assessment of the degree of exposure should include analy-
sis of urine for tetrachlorohydroquinone, chloranil, and the conjugated
compounds.
Large amounts of pentachlorophenol are found in the liver relative
to other tissues. Based on the known role of the liver in detoxifica-
tion of foreign substances, it is probable that metabolic breakdown takes
place in the liver, but direct information is not currently available.
Detoxification of other chlorophenols may also occur in this organ.
A.6.1.4 Elimination
Following human exposure to chlorophenols, the primary mode of elim-
ination has been shown to be through the urine. Information on the elim-
ination of chlorophenols other than pentachlorophenol is sketchy.
Following administration of 2-chlorophenol to dogs, 87% of the com-
pound was excreted in conjugation with sulfuric and glucuronic acids in
the urine. 2-Chlorophenol results from metabolism of chlorobenzene in
rabbits, and the compound is excreted in free and conjugated forms in the
urine; excretion rates are not available. 2,4-Dichlorophenol has been
-------
37
detected in rabbit and rat urine following nemacide [<9-(2,4-dichloro-
phenyl)0,0-diethyl phosphorothioate] administration. 2,4-Dichlorophenol
is apparently the major metabolite of nemacide in mammals. Approximately
70% of the nemacide dose appeared in the urine as 2,4-dichlorophenol
within three days of administration; the fate of the remaining 30% of
the compound is not known.
Following injection of the 3- or y-hexachlorocyclohexane isomers
into mice, a number of chlorophenols and their conjugates, including
2,4,5- and 2,4,6-trichlorophenol and 2,3,4,5-tetrachlorophenol, appeared
in the urine. When pentachlorophenol was administered to rats, 2,3,4,5-,
2,3,4,6-, and 2,3,5,6-tetrachlorophenol were detected as metabolites in
the urine.
Present evidence indicates that the lindane metabolites 2,4,5- and
2,4,6-trichlorophenol and 2,3,4,5- and 2,3,4,6-tetrachlorophenol are
excreted by rats for at least one month following treatment; this may
reflect the rate of lindane metabolism. On the other hand, following
administration of ronnel [0,0-dimethyl 0-(2,4,5-trichlorophenyl) phos-
phorothioate], rats excreted 2,4,5-trichlorophenol for two days. The
difference in these rates likely depends on the chemical nature of the
precursor compound. Although lack of information precludes definitive
conclusions, it is speculated that the tetrachlorophenol compounds in
particular may behave in a manner similar to pentachlorophenol because
their chemical structures and lipid solubilities are similar. Lower
chlorophenols should be excreted more rapidly due to their higher water
solubility.
Although the primary mode of pentachlorophenol excretion appears to
be the urine, fecal excretion also plays a role. Values ranging from 4%
of the injected dose in the rabbit to 14% in rats over a ten-day period
have been reported in the feces. In humans, initial elimination of penta-
chlorophenol in the urine may be very rapid, but return to urinary back-
ground levels of pentachlorophenol may take as long as one month. It is
difficult to determine from the studies whether all of the pentachloro-
phenol has been excreted within this time, whether some may be stored in
various deposits in the body, or whether there was continuous exposure.
A two-component urinary excretion pattern of pentachlorophenol by rats
has been demonstrated.
Dose and route of exposure also apparently affect the excretion
rate of pentachlorophenol. In humans, pentachlorophenol is excreted more
rapidly at high dose levels than when the body burden is lower. The
exact relationships between excretion rate and dose and between excretion
rate and route of exposure have not been verified. In mammals, the bulk
of pentachlorophenol administered appears to be excreted relatively
rapidly — approximately 50% is excreted in the urine in 24 hr for rats,
rabbits, and mice and 70% to 85% is eliminated in four days. Excretion
of the remaining pentachlorophenol may take longer, and the effect of
this low-level contamination on the organism is unknown.
-------
38
The applicability of the information on pentachlorophenol elimination
to other chlorophenols is uncertain. However, elimination of at least the
tetrachlorophenols may parallel that of pentachlorophenol.
A.6.2 EFFECTS
A.6.2.1 Physiological or Biochemical Role
There is no evidence that chlorophenols play a normal biochemical
or physiological role in humans or mammals.
A. 6.2.2 Toxicity
Except for pentachlorophenol, most information on the general toxic-
ity of chlorophenols to humans is derived from investigations with ex-
perimental animals. Documented human toxicity following pentachlorophenol
exposure is available, and much of the information on symptoms and patho-
logical changes is derived from these cases. No documented reports of
human systemic toxicity due to exposure to lower chlorophenols are
available.
A. 6.2.2.1 Mechanism of Action — All chlorophenol isomers examined
in this report appear to uncouple oxidative phosphorylation in higher
mammals and humans, leading to serious metabolic disturbances. The
potency of these compounds in producing this effect appears to increase
with increased chlorination of the parent phenol. The effect of chloro-
phenols on oxidative phosphorylation in rat liver mitochondrial prepara-
tions (Table A.6.2) and in rat brain homogenates has been determined.
Pentachlorophenol is the strongest inhibitor of oxidative phosphorylation,
followed by 2,3,4,6-tetrachlorophenol; tetrachlorophenol possesses about
50% of the activity seen with pentachlorophenol. Decreasing chlorination
results in decreased activity; 2,4,5-trichlorophenol possesses approxi-
mately 30% and 2,4,6-trichlorophenol possesses 5% of the activity of
pentachlorophenol. 2-Chlorophenol was the weakest chlorophenol tested
in this in vitro assay system.
Typical clinical signs of pentachlorophenol poisoning in experi-
mental animals correspond closely with clinical symptoms from poisoning
by higher chlorophenol isomers. Present evidence suggests that the toxic
action of chlorophenols, with the possible exception of 2-chlorophenol,
in experimental animals is due to inhibition of oxidative phosphorylation,
thereby short-circuiting metabolism. The dosages or concentrations re-
quired to elicit this effect are different for different compounds, but
with sufficient uptake of any of these compounds, symptoms similar to the
toxicological picture found with pentachlorophenol are likely to ensue.
The mechanism of action of 2-chlorophenol may be different. 2-Chlo-
rophenol is capable of causing convulsions in experimental animals.
Phenol can cause convulsions with no apparent effect on oxidative phos-
phorylation. 2-Chlorophenol is apparently more effective in eliciting
convulsions than phenol. Coupled with its relatively weak action on the
energy systems of the cell, this evidence indicates that the mechanism of
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39
TABLE A.6.2. EFFECT OF CHLOROPHENOLS ON OXIDATIVE
PHOSPHORYLATION IN RAT LIVER MITOCHONDRIA
I a
Compound , . *° /n ._ N
(micromoles/ liter)
2-Chlorophenol
2 , 4-Dichlorophenol
2,4, 6-Trichlorophenol
2,4, 5-Trichlorophenol
2,3,4, 6-Tetrachlorophenol
Pentachlorophenol
520
42
18
3
2
1
T a
LSO
(mg/liter)
67
7.0
3.6
0.59
0.46
0.27
Concentration required to decrease oxidative phosphory-
lation to 50% of normal levels.
Source: Adapted from Mitsuda, Murakami, and Kawai,
1963, Table I, p. 369. Reprinted by permission of the
publisher.
action of 2-chlorophenol may more closely resemble that found in phenol
poisoning; however, more information is needed. A convulsive effect is
also noted when 2,4,6-trichlorophenol is administered to experimental
animals. As Table A.6.2 indicates, the effect of 2,4,6-trichlorophenol
on oxidative phosphorylation is weaker than that of other higher chloro-
phenols. Thus, in some respects, 2,4,6-trichlorophenol poisoning may
have a mechanism of action similar to that of 2-chlorophenol in experi-
mental animals.
A general property of uncouplers is the ability to inhibit the
enzymes lactate dehydrogenase and hexokinase in in vitro systems. 2,4-
Dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, and
pentachlorophenol are all capable of inhibiting these enzymes; 2-chloro-
phenol has not been tested.
Pentachlorophenol is clearly a strong uncoupler of oxidative phos-
phorylation, but the molecular mechanism remains unclear. Biochemical
effects of pentachlorophenol have been divided into three groups, depend-
ing on the pentachlorophenol concentration. Low concentrations uncouple
oxidative phosphorylation and result in an increased respiration. High
levels drastically curtail glycolytic phosphorylation, causing inactiva-
tion of respiratory enzymes with a drastic reduction in respiration.
Intermediate amounts inhibit the action of mitochondrial ATPase and
myosin ATPase. Convincing evidence exists that binding of pentachloro-
phenol to mitochondrial protein is necessary for any of these biochemical
processes to occur. The basic effect of pentachlorophenol in uncoupling
oxidative phosphorylation may be responsible for all effects at the bio-
chemical level. The effects noted with high pentachlorophenol levels
may be due to (1) the drastic curtailment of metabolic processes in the
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40
cell and subsequent breakdown in other enzyme systems or (2) the direct
binding of pentachlorophenol to other crucial enzymes in the cell and
inactivation of other essential pathways. Total breakdown of mitochon-
drial integrity has been reported and could be the final stage of penta-
chlorophenol toxicity in the cell.
A.6.2.2.2 Local and Systemic Pathology — All chlorophenols tested
are irritating to the nose, throat, skin, and eyes. Local effects of
the various chlorophenols are summarized in Table A.6.3; detailed infor-
mation is found in later sections of the report. Chloracne has occurred
in humans following prolonged (over a period of years) contact with
several chlorophenol isomers (Table A.6.3). It is likely that chloracne
largely results from exposure to impurities found commonly in commercial
chlorophenol preparations. These impurities, namely chlorodibenzo-p-
dioxins, are capable of causing chloracne when they are applied in the
pure state.
TABLE A.6.3. LOCAL EFFECTS OF CHLOROPHENOLS ON HUMANS
OR EXPERIMENTAL ANIMALS
Skin effects Eye effects
Redness _, , Chemical _ ...... Corneal
, , Chloracne Irritation . .
and edema burn injury
2-Chlorophenol
2,4, -Dichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2,3,4, 6-Tetrachlorophenol
2,3,5, 6-Tetrachlorophenol
Tetrachlorophenol
Pentachlorophenol
Yes
Yes
Yes
Yes
Maybe
Yes
Yes
Yes
Yes
Maybe
Maybe
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Isomer not identified.
Except for pentachlorophenol, information on the tissue pathology
of experimental animals or humans following chlorophenol intoxication
is scant. Administration of 2-chlorophenol to the rat or the blue fox
resulted in marked kidney injury, fatty infiltration of liver tissue,
renal granular dystrophy, and necrosis of the stomach and intestinal
mucosa. Chronic feeding of 2,4-dichlorophenol to mice at daily levels
up to 230 mg/kg for six months resulted in only minor histological
changes in the liver. 2,4-Dichlorophenol is considered a relatively
safe substance, with 100 mg/kg daily as a maximum no-effect level.
Similarly, 2,4,5-trichlorophenol appears to be only mildly toxic.
Rabbits fed 20 doses of the compound (500 mg/kg in each dose) showed
-------
41
mild, reversible kidney and liver changes. Rats fed 2,4,6-trichloro-
phenol at levels of 10 to 1000 mg/kg body weight showed no adverse
effects at levels less than 100 mg/kg daily as judged by gross appear-
ance and behavior, mortality, food consumption, growth, hematologic
values, final average body and organ weight ratios, or gross and micro-
scopic examination of the tissues. At 300 or 1000 mg/kg daily, rats
sustained minor microscopic damage to the kidneys and liver. The pathol-
ogist stated that the changes in the liver and kidneys of the animals
were mild, reversible, and probably of minor significance. Pentachloro-
phenol data from experimental animal studies and autopsies of fatally
poisoned humans have been reported. Autopsies of victims showed moderate
to severe pathological changes in the gastrointestinal tract, lungs,
spleen, liver, kidneys, and cardiovascular system. The pathological
changes of pentachlorophenol intoxication are discussed in Section D.6.2.
The general hyperpyrexia caused by pentachlorophenol may be the indirect
cause of many of these pathological changes.
A.6.2.2.3 Acute Toxicity — The exact dosage in accidental or sui-
cidal poisoning cases is difficult to determine; therefore, experimental
animal studies are preferable for comparing the toxic effects of chloro-
phenols. Some typical LD50 values for chlorophenols are compiled in
Table A.6.4. As shown in the table, pentachlorophenol is the most toxic
phenol, although the toxicity of 2,3,4,6-tetrachlorophenol is close to
that of pentachlorophenol. 2-Chlorophenol appears to be approximately
five times less toxic than higher chlorophenols; 2,4-dichlorophenol is
still less toxic, and the trichlorophenol isomers must be administered
in gram-per-kilogram quantities to cause death in experimental animals.
Chlorophenols are separated into two general categories on the basis
of their toxicological effects: (1) the convulsive chlorophenols, in-
cluding 2-chlorophenol and 2,4,6-trichlorophenol, and (2) the noncon-
vulsive chlorophenols. Convulsions and tremors are very prominent when
experimental animals are treated with convulsive phenols; pronounced
hypotonia and coma are characteristic of poisoning by the nonconvulsive
chlorophenols. Poisoning by all chlorophenols is characterized by a
marked rise in temperature and, in most cases, an initial increase in
respiratory rate followed by a decreased rate and onset of coma. Clini-
cal signs of poisoning by the convulsive phenols generally occur in the
following sequence: (1) soon after administration of the compound, rest-
lessness and an increased rate of respiration are evident; (2) somewhat
later motor weakness develops and tremors and convulsions are induced by
noise or touch; (3) eventually, dyspnea, coma, and death occur. The
clinical symptoms of poisoning with nonconvulsive chlorophenols is quite
different. All of these symptoms apply to poisoning by pentachloro-
phenol. Toxicological symptoms of poisoning by other nonconvulsive chlo-
rophenols resemble those for pentachlorophenol, but all of these symptoms
may not be present when mammals are exposed to some of the lower chlori-
nated phenols. Tetrachlorophenol poisoning appears to most closely
resemble pentachlorophenol poisoning. Symptoms in humans poisoned by
acute or chronic high-level doses of pentachlorophenol include weight
loss, general weakness, fatigue, dizziness, mental weakness, headache,
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42
TABLE A.6.4. ACUTE TOXICITY OF CHLOROPHENOLS TO EXPERIMENTAL ANIMALS
Compound
2-Chlorophenol
2 , 4-Dichlorophenol
2 ,4 , 5-Trichlorophenol
2,4, 6-Tr ichlorophenol
2,3,4, 6-Tetrachlorophenol
2,3,5, 6-Tetrachlorophenol
Pen tachloropheno 1
Sodium pentachlorophenate
Animal
Rat
Rat
Albino rat
Rabbit
Rabbit
Guinea pig
Mouse
Blue fox
Unknown mammal
Rat
Rat
Rat
Mouse
Rat
Rat
Rat
Rat
Rat
Rat
Unknown mammal
Rat
Rat
Rat
Rat
Rat
Rat
Mouse
Rat
Mouse
Mouse
Rat
Rabbit
Guinea pig
Rabbit
Rabbit
Rat
Rabbit
Guinea pig
Rabbit
Route of
administration
Oral
Subcutaneous
Intraperitoneal
Subcutaneous
Intraveneous
Subcutaneous
Oral
Oral
Oral
Oral
Intraperitoneal
Subcutaneous
Oral
Oral
Oral
Oral
Oral
Subcutaneous
Intraperitoneal
Unknown
Oral
Oral
Oral
Intraperitoneal
Oral
Subcutaneous
Subcutaneous
Intraperitoneal
Intraperitoneal
Intraperitoneal
Oral
Oral
Oral
Cutaneous
Sub cutaneous
Oral
Oral
Oral
Cutaneous
LD50
(mg/kg)
670
950
230
950a
120*
800a
670
440
440
580
430
1730
1600
2830
2460
820
2960
2260
355
150,
1620*
2800
820
276
140
210
120
130
250a
500a
78
70-130
50-140
100-200
70-85
210
275
80-160
100-300
Source
Christensen and Luginbyhl, 1975
Christensen and Luginbyhl, 1975
Farquharson, Gage, and
Northover, 1958
Christensen and Luginbyhl, 1975
von Oettingen, 1949
Christensen and Luginbyhl, 1975
Bubnov, Yaphizov, and Ogryzkov,
1969
Bubnov, Yaphizov, and Ogryskov,
1969
Christensen and Luginbyhl, 1975
Christensen and Luginbyhl, 1975
Christensen and Luginbyhl, 1975
Christensen and Luginbyhl, 1975
Christensen and Luginbyhl, 1975
Howard and Durkin, 1973
Howard and Durkin, 1973
Deichmann, 1943
McCollister, Lockwood, and Rowe,
1961
Deichmann, 1943
Farquharson, Gage, and
Northover, 1958
Christensen and Luginbyhl, 1975
Howard and Durkin, 1973
Gosselin et al., 1976
Christensen and Luginbyhl, 1975
Farquharson, Gage, and
Northover, 1958
Deichmann, 1943
Deichmann, 1943
Bechold and Ehlrich, 1906
Farquharson , Gage , and
Northover, 1958
Christensen and Luginbyhl, 1975
Christensen and Luginbyhl, 1975
Deichmann et al., 1942
Flickinger, 1971
Flickinger, 1971
Dow Chemical Company, 1969a
Deichmann et al., 1942
Dow Chemical Company, 19692)
Dow Chemical Company, 19692)
Dow Chemical Company, 19692)
Dow Chemical Company, 19692)
TMinimum lethal dose.
Sodium salt of 2,4,5-trichlorophenol
-------
43
anorexia, nausea and vomiting, dyspnea, hyperpyrexia, respiratory dis-
tress, tachycardia, hepatomegaly, profuse perspiration, and elevated
basal metabolic rate. The most common symptoms of poisoning are general
weakness, weight loss, and profuse perspiration. Fever and profuse
sweating result from the uncoupling of oxidative phosphorylation. Hyper-
pyrexia may be the primary factor leading to circulatory and respiratory
failure due to the central and peripheral effects of fever as in heat
stroke. Although the exact dose of pentachlorophenol causing illness in
humans is not known, data indicate that pentachlorophenol quantities
absorbed through the skin of newborn infants can be lethal.
Fifty-one cases of poisoning from pentachlorophenol ingestion or
absorption have been reported, with 30 resulting in death. No specific
antidote is known, and death can occur in spite of conventional support-
ive therapy. In a recent case, the use of intravenous fluids and electro-
lytes was successful. In acute pentachlorophenol poisoning, onset of
symptoms is very rapid and death occurs in 2 to 3 hr. In nonfatal cases
of pentachlorophenol poisoning, onset of symptoms occurs at blood concen-
trations of 40 to 80 mg/liter with corresponding concentrations of 40 to
80 mg/liter in urine. Blood levels in fatal cases ranged from 46 to 156
mg/liter and urine levels ranged from 28 to 520 mg/liter. The acute oral
lethal dose of pentachlorophenol has been listed as 29 mg/kg body weight
for humans; however, the actual amount required to cause systemic toxicity
in humans is unknown and probably depends on the renal competency of the
individual. For individuals whose ability to excrete the compound is
reduced, the lethal dose may be considerably lower. Most cases of fatal
and nonfatal human pentachlorophenol intoxication have resulted from
improper handling of the compound. Elevated pentachlorophenol levels
have been reported in the blood and urine of workers in the wood preserva-
tion industry.
A.6.2.2.4 Chronic Toxicity
A.6.2.2.4.1 In experimental animals — The chronic toxicity of lower
chlorophenols in experimental animals has not been adequately studied.
Mice fed 2,4-dichlorophenol over a six-month period were evaluated for
average body weight, food consumption, organ weight, and histology of
major organs. No adverse changes in the behavior, growth rate, or levels
of blood glutamic oxaloacetate and glutamic or pyruvate transaminases
were found in mice receiving up to 230 mg/kg daily; minor histological
changes occurred in the liver. A similar low chronic toxicity has been
demonstrated for 2,4,5-trichlorophenol. Rats daily fed 2,4,5-trichloro-
phenol at levels up to 1000 mg/kg body weight sustained only minor micro-
scopic damage to the kidneys and liver. Moderate, probably reversible,
changes occurred in animals receiving 2,4,5-trichlorophenol at daily
dosages greater than 300 mg/kg body weight. It has been speculated that
the toxicity of 2,4,6-trichlorophenol and 2-chlorophenol may parallel the
relatively low toxicity of 2,4-dichlorophenol or 2,4,5-trichlorophenol.
Chronic effects of the tetrachlorophenol isomers, on the other hand, are
speculated to more closely resemble the chronic effects documented for
pentachlorophenol. Specific information is not available.
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44
No chronic systemic disease was noted in rabbits when pentachloro-
phenol was applied cutaneously at levels low enough to avoid gross skin
damage. Daily subcutaneous or intraperitoneal doses of pentachlorophenol
to rabbits may cause severe symptoms and death if the doses are high enough.
The amount of pentachlorophenol in small divided doses necessary to cause
death is very similar to the minimum lethal dose with a single administra-
tion of the compound. Renal competency may determine the chronic levels
of pentachlorophenol which may be tolerated. Chronic poisoning results
not from a storage-type accumulation of the compound in the system, but
rather from uptake of the substance in excess of its excretion rate.
Rats fed diets containing pentachlorophenol at 1 to 3 mg/kg for 90 days
to two years did not show adverse health effects. Levels of 10 to 30
mg/kg caused some changes but were not lethal.
In summary, lower chlorophenols appear to be only mildly toxic
following high-level chronic doses. Chronic pentachlorophenol poisoning
can result when daily exposures are sufficient to achieve a steady-state
level of pentachlorophenol in the organism which is high enough to cause
systemic intoxication. Chronic effects resulting from storage-type
accumulation of pentachlorophenol or any other chlorophenols in experi-
mental animals have not been demonstrated and are not expected to occur
because of the rapid elimination of chlorophenols.
A.6.2.2.4.2 In humans — Chronic effects resulting from low-dose ex-
posure to chlorophenols have not been reported. Long- or short-term chronic
effects following exposure to chlorophenols other than pentachlorophenol
have not been demonstrated. Apparently, low-dose pentachlorophenol exposure
does not result in chronic effects in humans. Although low, but detectable,
levels of pentachlorophenol have been found in the blood and urine of non-
occupationally exposed persons, chronic effects resulting from these pre-
valent levels have not been demonstrated. Chronic exposure to pentachloro-
phenol among individuals involved in the wood-treatment industry may have
reversible effects on kidney function. Significant differences in blood
and urinary phosphorus levels and in creatinine clearance have been found
in wood treaters before, during, and after vacation. It was concluded
that pentachlorophenol exposure results in reversible decreases in creati-
nine clearance and phosphorus reabsorption in the kidney. Such minor
effects on kidney function are probably insignificant in most cases; how-
ever, the question warrants further study.
Other evidence indicates that workers chronically exposed to penta-
chlorophenol may have significantly higher prevalence of C-reactive protein
in the sera. Although the clinical significance of these elevated levels
is not known, C-reactive protein levels are often elevated in acute states
of various inflammatory disorders or tissue damage. It has been inferred
that the elevated levels of C-reactive protein in individuals exposed to
pentachlorophenol indicate inflammation or tissue injury. These data have
not been verified, and the significance of elevated levels of C-reactive
protein in individuals exposed to pentachlorophenol remains speculative.
Pentachlorophenol levels of 12 to 45 ug/kg have been found in fat
of individuals not occupationally exposed. The significance of these
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45
pentachlorophenol levels in the fat is unknown; pentachlorophenol in fat
at these levels is toxicologically insignificant. Levels of pentachloro-
phenol in the fat of individuals actively exposed to the compound in their
daily work have not been reported. The potential for pentachlorophenol
biomagnification in human adipose tissue is an open question warranting
further investigation.
The nearly ubiquitous presence of pentachlorophenol in the human
population may result in part from the metabolism of other organochlorine
compounds. For example, pentachlorophenol has been isolated from the
excreta of rats and monkeys following administration of lindane. These
results suggest an alternative explanation for the nearly ubiquitous
presence of pentachlorophenol in the human population and question the
tacit assumption that pentachlorophenol in human urine, serum, and tissue
results from exposure to pentachlorophenol. Additional investigations in
these areas are urgently needed.
A.6.2.3 Carcinogenicity
Pentachlorophenol and 2,4,6-trichlorophenol have shown no significant
indication of tumorigenicity following oral administration to mice. How-
ever, repeated application of phenol and some substituted phenols is
reportedly capable of promoting the appearance of skin tumors in mice
following a single initiating dose of dimethyIbenzanthracene. Tumors
also developed in mice (not exposed to dimethylbenzanthracene) treated
with phenol alone over a long period. When 2-chlorophenol, 2,4-dichloro-
phenol, 2,4,5- and 2,4,6-trichlorophenol, and pentachlorophenol were
tested in a similar system, no tumorigenic or tumor-promoting activity
was seen with 2,4,6-trichlorophenol or pentachlorophenol; 2-chlorophenol,
2,4-dichlorophenol, and 2,4,5-trichlorophenol possessed approximately the
same activity in promoting tumor formation as phenol. Both benign and
malignant tumors were formed. However, no tumorigenic effect was seen in
the absence of an initiating dose of dimethylbenzanthracene.
A.6.2.4 Teratogenicity
2,4,5-Trichlorophenol and pentachlorophenol are the only chloro-
phenols tested for possible teratogenic effects in experimental animals.
No teratogenic effect of 2,4,5-trichlorophenol was seen at daily doses
of 0.9 or 9 mg/kg body weight administered on days 6 through 15 of preg-
nancy. Pentachlorophenol is fetotoxic but is not truly teratogenic in
rats and the golden Syrian hamster.
A.6.2.5 Mutagenicity
Data on possible mutagenic effects of lower chlorophenols are not
available. Pentachlorophenol did not demonstrate mutagenic properties
when tested in a microbiological or mammalian system or when tested for
mutagenic properties in the fruit fly (Drosophila melanogaster).
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46
A.6.2.6 Aplastic Anemia
One case of aplastic anemia due to pentachlorophenol and a tetra-
chlorophenol isomer has been reported. The individual was exposed to a
formulation containing pentachlorophenol and tetrachlorophenol. Because
the postmortem examination failed to reveal any other cause for aplastic
anemia, it was concluded that the damage to the bone marrow was caused by
these chlorophenols. No reports of aplastic anemia resulting from exposure
to other chlorophenols were found.
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47
SECTION A.6
REFERENCES
1. Bechold, H., and P. Ehrlich. 1906. Beziehungen zwischen chemischer
Konstitution und Desinfektionswirkung (Relation between Chemical
Constitution and Disinfecting Action). Z. Physiol. Chem. 47:173-199.
2. Bubnov, W. D., F. N. Yaphizov, and S. E. Ogryzkov. 1969. The Toxic
Properties of Activated o-Chlorophenol for White Mice and Blue Foxes.
Tr. Vses. Nauchno Issled. Inst. Vet. Sanit. Ektoparazitol. 33:258-263.
3. Christensen, H. E., and T. T. Luginbyhl, eds. 1975. Registry of
Toxic Effects of Chemical Substances. U.S. Department of Health,
Education, and Welfare, Rockville, Md. pp. 861-862.
4. Deichmann, W. 1943. The Toxicity of Chlorophenols for Rats. Fed.
Proc. Fed. Am. Soc. Exp. Biol. 2(l):76-77-
5. Deichmann, W., W. Machle, K. V. Kitzmiller, and G. Thomas. 1942.
Acute and Chronic Effects of Pentachlorophenol and Sodium Penta-
chlorophenate upon Experimental Animals. J. Pharmacol. Exp. Ther.
76:104-117.
6. Dow Chemical Company. 1969a. Hazards Due to Toxicity and Precautions
for Safe Handling and Use. Antimicrobial Agents, Section IV-7,
Dowicide 7 Antimicrobial. Midland, Mich. 2 pp.
7. Dow Chemical Company. 1969Z?. Hazards Due to Toxicity and Precautions
for Safe Handling and Use. Antimicrobial Agents, Section IV-12,
Dowicide G Antimicrobial. Midland, Mich. 2 pp.
8. Farquharson, M. E., J. C. Gage, and J. Northover. 1958. The Bio-
logical Action of Chlorophenols. Br. J. Pharmacol. 13:20-24.
9. Flickinger, C. W. 1971. Pentachlorophenol and Sodium Pentachloro-
phenate (internal report). Koppers Co., Pittsburgh. 27 pp.
10. Gosselin, R. E., H. C. Hodge, R. P. Smith, and M. N. Gleason. 1976.
Clinical Toxicology of Commercial Products: Acute Poisoning, 4th ed.
Williams and Wilkins Co., Baltimore, pp. 130-132.
11. Howard, P. H., and P. R. Durkin. 1973. Chlorophenols. In: Pre-
liminary Environmental Hazard Assessment of Chlorinated Naphthalenes,
Silicones, Fluorocarbons, Benzenepolycarboxylates, and Chlorophenols.
U.S. Environmental Protection Agency, Washington, D.C. pp. 204-263.
12. McCollister, D. D., D. T. Lockwood, and V. K. Rowe. 1961. Toxicologic
Information on 2,4,5-Trichlorophenol. Toxicol. Appl. Pharmacol.
3:63-70.
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48
13. Mitsuda, H., K. Murakami, and F. Kawai. 1963. Effect of Chloro-
phenol Analogues on the Oxidative Phosphorylation in Rat Liver
Mitochondria. Agric. Biol. Chem. 27(5):366-372.
14. von Oettingen, W. F. 1949. The Halogenated Phenols. In: Phenol
and Its Derivatives: The Relation between Their Chemical Constitu-
tion and Their Effect on the Organism. National Institute of Health
Bulletin No. 190. U.S. Public Health Service, Washington, D.C.
pp. 193-220.
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A.7 ENVIRONMENTAL DISTRIBUTION AND TRANSFORMATION
A.7.1 TRENDS IN PRODUCTION AND USE
Among the chlorophenols examined in this report, only three — 2,4,6-
trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol — have
been used to any large extent in the environment. 2,4,6-Trichlorophenol,
2,3,4,6-tetrachlorophenol, and pentachlorophenol are mainly used as fun-
gicides and microbicides, particularly for the preservation of wood,
leather, and glue. 2,4,6-Trichlorophenol and 2,3,4,6-tetrachlorophenol
are used to only a small extent, but pentachlorophenol is widely used in
the wood preservation industry as well as for preservation of a wide
variety of other materials. Pentachlorophenol has also been used as a
herbicide and preharvest desiccant, as an algicide or molluscicide, and
in food processing plants and pulp mills for the control of slime and
mold. Although production figures for 2,4,6-trichlorophenol and 2,3,4,6-
tetrachlorophenol are not available, the production of pentachlorophenol
(26,000,000 kg in 1976) far exceeds the estimated production and usage
of the other two chlorophenols. Obviously, the potential for environ-
mental contamination is greatest for pentachlorophenol.
2-Chlorophenol, 2,4-dichlorophenol, and 2,4,5-trichlorophenol are
not used to any large extent as preservatives or microbicides. The
principal uses of these compounds are as intermediates for the manufac-
ture of higher chlorophenols or as intermediates for the manufacture of
other organic compounds, including the widely used herbicides 2,4-
dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic
acid (2,4,5-T). Other phenoxyalkanoic herbicides are also manufactured
with these compounds as precursors. Because the direct usage of these
compounds as bactericides or germicides is probably negligible, environ-
mental contamination is most likely to result from degradation of com-
monly used pesticides in the environment.
A.7.2 SOURCES OF POLLUTION
Information on the atmospheric distribution of chlorophenols other
than pentachlorophenol is not available. Discharges of lower chlorophe-
nols to the atmosphere may occur in facilities where these compounds and
the phenoxyalkanoic herbicides are manufactured. Because all lower chlo-
rophenols are relatively volatile, volatilization from water, soil, foli-
age, and impervious surfaces may play an important role in their dispersal
to the atmosphere. Incineration of containers and trash containing chlo-
rophenols could generate volatile products to the atmosphere.
Monitoring data for pentachlorophenol in the general atmosphere are
unavailable. Circumstantial evidence indicates that pentachlorophenol may
be present in the atmosphere. Levels of pentachlorophenol in rainwater
and snow samples taken from the Mauna Kea Summit in Hawaii indicate that
pentachlorophenol is likely present in the atmosphere either as a vapor
or as an occlusion of dust particles and that the compound is likely re-
moved from the atmosphere by washout. Pentachlorophenol may be discharged
49
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50
in gaseous and particulate forms from chemical firms that manufacture
pentachlorophenol, but detailed information on pentachlorophenol levels
in the atmosphere surrounding such plants is not available.
Monitoring data on the presence of monochlorophenols, dichlorophenols,
trichlorophenols, and tetrachlorophenols in air, water, or soil are not
available. Monitoring data for pentachlorophenol levels in water are also
rare. Fish kills following industrial accidents involving spillage and
seepage of concentrated pentachlorophenol as well as deleterious effects
on aquatic organisms following the widespread distribution of pentachloro-
phenol as a molluscicide or algicide have been reported. However, these
lethal occurrences are usually associated with the presence of extremely
high levels of pentachlorophenol in water. Documentation of low-level
pentachlorophenol contamination of water is not available. Pentachloro-
phenol is known to be present in treated and untreated wastewaters from
wood treatment plants. Pentachlorophenol has also been detected in storm
water draining industrial sites where treated lumber has been stored and
in municipal sewage. Measurable pentachlorophenol levels have been de-
tected in the Willamette River in Oregon, in a creek in Pennsylvania,
and in the drinking water supplies of Tallahassee, Florida, and Corvallis,
Oregon. Levels are generally low, and the presence or absence of penta-
chlorophenol residues in other water bodies is speculative.
Industrial waste discharge is likely the principal point source of
water pollution by chlorophenols. During the manufacture of chlorophenols
and the widely used herbicides 2,4-D, 2,4,5-T, and silvex, chemical waste
is generated from incomplete reaction of the starting material, by-product
formation, and incomplete recovery of desired products. These wastes con-
tain a variety of phenols and other compounds. A typical waste arising
from the manufacture of 2,4-D and 2,4,5-T contains 2-chlorophenol, 2,4-
dichlorophenol, 2,4,5-trichlorophenol, and other chlorinated phenols. Run-
off from urban and agricultural watersheds could be an important nonpoint
source of chlorophenols in aquatic environments, but this has not been
reported. Primary sources include the presence of chlorophenols as impur-
ities in commercial formulations of the phenoxyalkanoic herbicides and as
degradation products of these compounds in soils.
The primary source of soil contamination by chlorophenols is probably
through the application of the phenoxyalkanoic herbicides 2,4-D, 2,4,5-T
and its derivatives, and silvex. Additionally, trichlorophenols and tetra-
chlorophenols may appear in soil folllowing application and degradation of
pentachlorophenol or lindane. Soil contamination by pentachlorophenol is
likely indirect except when the chemical is used as a herbicide or pre-
harvest desiccant. Monitoring data for chlorophenol levels in soil are
not available, except for soil migration studies around pentachlorophenol-
treated poles.
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A.7.3 ENVIRONMENTAL FATE
A.7.3.1 Mobility and Persistence in Air
The movement, fate, and persistence of chlorophenols in the atmos-
phere are matters for speculation. Circumstantial evidence (the detection
of pentachlorophenol in rainwater and snow) indicates that pentachloro-
phenol is present in the atmosphere; however, the presence of any other
chlorophenol in the atmosphere has not been documented.
A.7.3.2 Mobility and Persistence in Aquatic Environments
Chlorophenols may be present in aquatic environments in one or more
of the following three forms: (1) dissolved in either free or complexed
form, (2) adsorbed to suspended and/or bottom sediments, or (3) carried
in biological tissues. Movement of the compounds in water has not been
well studied, but it is believed that mobility depends primarily on hydro-
logical considerations such as currents and, in the case of transportation
by organisms, on movement and migration of the organisms. The persistence
of chlorophenols in the aquatic environment depends on a number of envi-
ronmental variables, but the interrelationships have not been fully char-
acterized. Dissipation of chlorophenols from the aqueous phase may occur
by volatilization to the atmosphere, photoinactivation, sorption to sus-
pended and/or bottom sediments, or biodegradation. The contribution of
volatilization to the dissipation of chlorophenols from aquatic systems
is unclear. The pentachlorophenol content of aerated solutions decreases
rapidly in laboratory experiments, presumably due to volatilization. The
higher vapor pressures of other chlorophenols suggest that volatilization
plays a role in their dissipation from water; however, definitive data
are not available.
Many organic compounds, including chlorophenols, undergo photochem-
ical decomposition when exposed to ultraviolet light. Photochemically
induced degradation occurs at surfaces of airborne particulates and water.
In finding their way to surfaces by various mechanisms, chlorophenols are
exposed to sunlight and are thereby susceptible to photochemical degrada-
tion. Information on photodecomposition of 2-chlorophenol is not avail-
able. 2,4-Dichlorophenol rapidly degrades in aqueous solutions exposed
to ultraviolet light. Direct information on the photochemical reactions
of trichlorophenols and tetrachlorophenols is scant. Insight into their
photodecomposition has been obtained from closely related compounds such
as pentachlorophenol and 2,4,5-T. 2,4,5-Trichlorophenol is subject to
rapid photodecomposition. Information is lacking on the photodecomposi-
tion of 2,4,6-trichlorophenol or any of the tetrachlorophenol isomers.
These compounds are likely subject to photodecomposition when conditions
are appropriate (i.e., water of sufficient clarity to allow adequate ul-
traviolet penetration). Evidence exists that pentachlorophenol and sodium
pentachlorophenate are subject to rapid photodecomposition in aqueous
solution. Practical experience in the field indicates that photodecom-
position may be a primary mode of pentachlorophenol dissipation in aquatic
systems under some conditions. The extent of photoinduced losses of
chlorophenols in natural systems has yet to be demonstrated. Despite
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52
ready photoinactivation of chlorophenols in laboratory systems, condi-
tions which prevent adequate ultraviolet penetration of water are fre-
quently found in the environment; therefore, the major route of
cb.lorophenol dissipation in water results from biodegradation.
Adsorption to suspended and/or bottom sediments may also play a
role in the dissipation of chlorophenols from water. Laboratory studies
indicate that in general monochlorophenols, dichlorophenols, and tri-
chlorophenols are only weakly sorbed by soil particles. Thus, removal
of these compounds from the aqueous system by sorption appears unlikely.
On the other hand, pentachlorophenol may be strongly sorbed to certain
soil types when conditions such as pH are appropriate. Dissipation of
pentachlorophenol from aqueous systems through sorption is a likely
possibility; however, the extent to which sorption contributes to the
removal of pentachlorophenol from water remains speculative. The chemi-
cal similarity of the tetrachlorophenols to pentachlorophenol suggests
that sorption may play a role in the dissipation of 2,3,4,6-tetrachloro-
phenol and other tetrachlorophenol isomers from aquatic systems.
Biodegradation is probably the major route of chlorophenol dissipa-
tion from aquatic environments. In view of the known microbial toxicity
of chlorophenols, ready degradation of these compounds in aquatic environ-
ments probably requires acclimated or adapted bacterial strains. This
expectation has been confirmed in experimental studies. Low concentra-
tions of 2-chlorophenol added to domestic sewage were not removed during
periods of 20 to 30 days; however, similar concentrations added to pol-
luted river waters dissipated in 15 to 23 days. Other experiments have
indicated that the removal of monochlorophenols from water requires the
presence of specialized microflora. Activated sludge preparations accli-
mated to 2-chlorophenol rapidly degrade the compound. In a similar vein,
2,4-dichlorophenol is degraded rapidly in the presence of acclimated
activated sludge.
The location of chlorine on the phenol nucleus affects degradation.
The presence of a chlorine atom at the meta position of the phenol ring
retards biodegradation. For example, 2,4,5-trichlorophenol is more per-
sistent than 2,4,6-trichlorophenol. Limited data indicate that 2,4,5-
and 2,4,6-trichlorophenol are degraded rapidly under specified conditions
in activated sludge or aeration lagoon effluent. Although no data are
available to indicate the persistence of 2,3,4,6-tetrachlorophenol in
aquatic systems, soil suspensions have been tested for ability,to degrade
chlorophenols. These data may shed some light on the expected persistence
of the various chlorophenol isomers in natural water-soil systems. Table
A.7.1 indicates that 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol,
and pentachlorophenol are persistent in the absence of acclimated micro-
organisms. When acclimated microorganisms are present, all chlorophenol
isomers are degraded relatively rapidly, with pentachlorophenol being
the most refractory.
Many investigations have shown that pentachlorophenol degradation
does not occur readily in aquatic environments (Table A.7.1). However,
other investigations have indicated that under appropriate conditions -
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53
TABLE A.7.1. DEGRADATION OF CHLOROPHENOLS IN ACCLIMATED
ACTIVATED SLUDGEa
Ring Production of
,, , degradation chloride ion
Compound 6
(%) (days) (%) (days)
2-Chlorophenol
3-Chlorophenol
4-Chlorophenol
2 , 4-Dichlorophenol
2 , 5-Dichlorophenol
2,4, 6-Trichlorophenol
Sodium pentachlorophenate
Dichloroquinone
2, 5-Dichlorophenol benzoquinone
100
100
100
100
52
100
0
100
30
3
2
3
5
4
3
4
1
1
100
100
100
100
16
75
0
50
0
4
3
3
5
4
3
4
3
1
Concentration of 100 mg/liter.
Source: Adapted from Ingols, Gaffney, and Stevenson, 1966,
Table IV, p. 631. Reprinted by permission of the publisher.
pentachlorophenol is degraded rapidly in activated sludge or under labor-
atory conditions where suitably activated microbial populations are pres-
ent. Under specified conditions, pentachlorophenol levels in water
declined to negligible amounts in 48 hr, but other experiments indicated
that substantial amounts of pentachlorophenol may remain in a laboratory
system for more than 120 days. Thus, depending on environmental condi-
tions, pentachlorophenol may degrade rapidly and pose little or no environ-
mental hazard, or it may have marked longevity, thereby posing a potential
hazard of indeterminate proportions. Despite the lack of data on the
persistence of 2,4,5,6-tetrachlorophenol, this compound is speculated to
behave in a manner similar to pentachlorophenol. None of the chloro-
phenols should be allowed to reach unacclimated bodies of water where
their persistence may be considerably extended. The ecological effects
resulting from their presence remain largely undefined.
A.7.3.3 Mobility and Persistence in Soil
The movement of chlorophenols in soil depends on the interaction and
persistence of the chemicals. More persistent compounds have a greater
chance to interact with the soil particles, particularly by the sorption
process. The extent of sorption determines whether the chemicals are car-
ried in association with eroded soils during overland flow or are leached
through the soil profile during infiltration. Soil factors affecting sorp-
tion include pH, moisture, and clay and organic matter content. Sorption
characteristics of chlorophenols other than pentachlorophenol have not been
studied adequately. Based on limited data, 2-chlorophenol, 2,4-dichloro-
phenol, and 2,4,5- and 2,4,6-trichlorophenol seem to be sorbed only weakly
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54
by soil particles. Thus, the potential for downward movement through the
soil profile and for groundwater contamination exists. Severe cases of
contamination due to infiltration of 2,4-D and 2,4-dichlorophenol into the
groundwater have been reported. Two instances of groundwater pollution
resulting from emptying wastes containing 2,4-D and 2,4-dichlorophenol into
local sewage systems and from discharge of the compounds into lagoons have
been reported. In view of the ready biodegradability of these compounds
in soil and the very small quantities which are expected to contaminate
soil in the routine usage of the herbicides 2,4-D and 2,4,5-T, groundwater
contamination is not likely to occur. However, when highly concentrated
solutions have been allowed to seep through the soil, contamination of
groundwater has resulted. Pentachlorophenol, on the other hand, is tightly
bound by soil particles and the likelihood of leaching through the soil
profile into groundwater is reduced markedly. 2,3,4,6-Tetrachlorophenol
.may share this property with pentachlorophenol, but direct data are not
available.
Biodegradation plays a crucial role in the dissipation of the chlo-
rophenols from soil. Microbial decomposition in soil suspensions occurs
rapidly for 2-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol,
but 2,4,5-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophe-
nol are more persistent (Table A.7.2). All chlorophenols persist longer
in soil under conditions unfavorable for microbial growth and activity;
the presence of acclimated populations of bacteria and fungi increases
the degradation rate of these compounds. Under appropriate conditions,
even the more persistent chlorophenols (2,4,5-trichlorophenol-, 2,3,4,6-
tetrachlorophenol, and pentachlorophenol) are degraded. The rate of
degradation depends on a wide variety of soil parameters. The complexity
of the interactions between soil microbial populations and any given
chlorophenol frequently precludes general predictions of persistence.
For example, persistence of pentachlorophenol in soil ranges from 21 to
200 days, depending on the specific conditions at the site of application.
A.7.4 Waste Management
Chlorophenols are degraded readily in well-designed wastewater treat-
ment plants. However, dumping or seepage of these compounds into unaccli-
mated bodies of water or shock loading of sewage treatment plants may pose
serious hazards. Wastewater treatment of chlorophenols involves relatively
long retention times and precautions to avoid leaching of lower chlorophe-
nol isomers through the soil profile into groundwater supplies. The dis-
tribution of chlorophenol-metabolizing microorganisms in the environment
is not known, and further research in this area is warranted. The major
ecological hazard is likely posed by highly chlorinated chlorophenols such
as pentachlorophenol and tetrachlorophenols. In view of the fact that
these are the most toxic chlorophenols, caution should be used in the dis-
posal of these compounds to insure that large quantities do not reach
sensitive areas of the environment.
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TABLE A.7.2. MICROBIAL DECOMPOSITION OF CHLOROPHENOLS
IN SOIL SUSPENSIONS
Time for complete
dissipation (days)
Compound
Dunkirk Mardin
silt loama silt loama
Phenol 2 1
2-Chlorophenol 14 47
3-Chlorophenol >72 >47
4-Chlorophenol 9 3
2-Bromophenol 14 b
3-Bromophenol >72 b
4-Bromophenol 16 b
2,4-Dichlorophenol 9 5
2,5-Dichlorophenol >72 b
2,4,5-Trichlorophenol >72 >47
2,4,6-Trichlorophenol 5 13
2,3,4,6-Tetrachlorophenol >72 b
Pentachlorophenol >72 b
2,4-D 26 23
2,4,5-T >205 >47
Silvex [2-(2,4,5-trichlorophenoxy)
propionic acid] >205 >47
fSubstrate added, 50 mg/liter.
No data.
Source: Adapted from Alexander and Aleem, 1961, Tables I
and II, p. 45. Reprinted by permission of the publisher.
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56
SECTION A.7
REFERENCES
1. Alexander, M., and M.I.H. Aleem. 1961. Effect of Chemical Structure
on Microbial Decomposition of Aromatic Herbicides. J. Agric. Food
Chem. 9(1):44-47.
2. Ingols, R. S., P. E. Gaffney, and P. C. Stevenson. 1966. Biological
Activity of Halophenols. J. Water Pollut. Control Fed. 38(4):629-635.
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A.8 ENVIRONMENTAL INTERACTIONS AND THEIR CONSEQUENCES
A.8.1 ENVIRONMENTAL CYCLING OF CHLOROPHENOLS
The sources, distribution, and fate of chlorophenols in soil,
aquatic environments, and the atmosphere are discussed in Section A.7.
A possible cycle of these chemicals in the environment showing likely
sources of contamination, interaction, and sinks is depicted in Figure
A.8.1. Caution should be used in interpretation of this cycle because
the limited data available make it difficult to establish any pattern
of distribution and flow of the chemicals into various parts of the
environment.
Soil and aquatic systems could be contaminated through direct usage
of chlorophenols or closely related compounds, discharge of industrial
wastes and sewage, and chlorination of water containing phenols. Al-
though no documentation is available on the relative contribution of
each source, it is logical that contamination with 2-chlorophenol,
2,4-dichlorophenol, and 2,4,5-trichlorophenol occurs mainly by applica-
tion of the chemically related phenoxyalkanoic herbicides such as
2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic
acid (2,4,5-T), which may contain chlorophenols as contaminants and
produce them as degradation products. 2,4,6-Trichlorophenol is used as
a microbicide, and residues are expected to result from the usage and
manufacture of the compound. Pentachlorophenol and 2,3,4,6-tetrachloro-
phenol have been used as broad-spectrum biocides and wood preservatives.
2,3,4,6-Tetrachlorophenol is used only sparingly, but pentachlorophenol
is used extensively as a wood preservative and microbicide. Additionally,
2,3,4,6-tetrachlorophenol may be present as an impurity of technical-grade
pentachlorophenol preparations. Leaching from preservative-treated items
and dissemination of pentachlorophenol as a herbicide, molluscicide, algi-
cide, or slimicide are likely sources for pentachlorophenol contamination
of the environment. Chlorophenols are volatile; the degree of volatility
decreases with increased chlorine substitution. Data on the presence of
chlorophenols in the atmosphere and their subsequent redeposition during
precipitation and fallout are extremely limited.
Chlorophenols undergo physicochemical and biological interactions
with various components of the environment. The chemicals can be sorbed
by soils, sediment, and airborne particulate material. Sorption plays a
major role in the downward and overland movement of contaminants from
soil surfaces. Tightly bound compounds tend to associate with the eroded
soil particles during runoff, but weakly bound compounds may move with
the water phase during runoff and infiltration. Limited evidence indi-
cates that the sorption of 2-chlorophenol, 2,4-dichlorophenol, and perhaps
the trichlorophenols is insignificant, suggesting that these compounds are
mobile and would not be associated with particulate materials in the run-
off process. On the other hand, 2,3,4,6-tetrachlorophenol and penta-
chlorophenol appear to be tightly bound to soil particles under most
conditions. Thus, these compounds are expected to remain in the soil
until biodegradation or other dissipation mechanisms remove them.
57
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ORNL-DWG 78-10497
DEGRADATION
DIRECT
APPLICATION, SPILLAGE,
INDUSTRIAL
WASTE .SEWAGE
PRECIPITATION,
FALLOUT
PRECIPITATION,
FALLOUT
- -ABSORPTION,.- DECAY" _ ^l_ ~^V— - —
- - • T . . ._ . — • — —^. —
——' *— ~ t^= _^^~—r= EXCRETION——=n AQUATIC
ADSORPTION-ZDESeRPTIONL-:- DECAY AUU«IH,
=r*^ ORGAN ISM
-SUBSURFACE WATER'-^--fc— ^E-^-^---r
DIRECT APPLICATION, SPILLAGE,
INDUSTRIAL WASTE, SEWAGE,
WATER TREATMENT
Ui
oo
DEGRADATION
DEGRADATION
Figure A.8.1 Possible cycling of chlorophenols in the environment.
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59
The rates of chemical and biological transformation of chlorophenols
determine their persistence and subsequent degree of movement in a partic-
ular segment of the environment. Chemical oxidation may occur during
treatment of wastewater, and photodecomposition is possible when the
compounds are present at water, soil, and airborne particulate surfaces
exposed to sunlight. It has been shown, although data are limited and
fragmentary, that each chlorophenol reviewed in this report can be assim-
ilated by soil and aquatic microorganisms, absorbed by plants, and
absorbed and/or ingested by mammals. Microbial degradation appears to be
the principal mechanism of dissipation. The degree of metabolism and
mode of distribution of absorbed or ingested chlorophenols in plants,
wildlife, and mammals may influence possible bioaccumulation. Evidence
suggests that pentachlorophenol may bioaccumulate in liver and kidney to
a limited extent in terrestrial animals, and limited biomagnification
almost certainly occurs in aquatic ecosystems. Information on the bio-
accumulation of other chlorophenols is lacking. Bioaccumulated chloro-
phenols, if they persist, can be returned either to the soil and water
system during decay and excretion or be consumed by higher organisms,
including humans, through the food chain.
A.8.2 CHLOROPKENOLS IN FOOD
With the exception of pentachlorophenol, none of the chlorophenols
examined in this report are used directly in agricultural production.
In fact, the limited use of pentachlorophenol as a herbicide places it
generally in the same category. Despite this lack of agricultural use,
the compounds may find their way into crops (e.g., metabolism of chemi-
cally related herbicides by plants or animals). Degradation of lindane
in rats results in the production of a large number of chlorophenol
isomers (Figure A.8.2). The extent to which herbicides or other similar
organic chemicals are degraded to form chlorophenols in the environment
remains speculative. Present data indicate that these processes are
likely to occur, but the extent to which these lower chlorophenols appear
in foods is unknown. Large amounts of 2,4-D and 2,4,5-T must be con-
sumed to cause detectable concentrations of chlorophenols in domestic
animals; it seems highly unlikely that sufficient quantities of the
phenoxyalkanoic herbicides would be ingested to cause a chlorophenol
problem.
Transfer of the chlorophenols to humans through the food chain is
remote, with the exception of pentachlorophenol. Small amounts of penta-
chlorophenol have been detected in food samples analyzed by the Food and
Drug Administration of the U.S. Department of Health, Education, and
Welfare. Thus, some portion of the nation's population is exposed to
low levels of pentachlorophenol through food consumption, but it is
impossible to describe the extent of the associated hazards. The source
of the pentachlorophenol in food is unclear. Contact of produce and
meat with pentachlorophenol-treated items during packaging and distribu-
tion may in part be responsible for low pentachlorophenol levels in food
products. Also, the widespread use of pentachlorophenol as a wood pre-
servative may allow some degree of absorption by plants and domestic
animals in contact with treated lumber. Whatever the source, no chronic
health problems have been associated with the low levels of pentachloro-
phenol detected in human urine.
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60
ORNL-DWG 78 — 10498
y-1,2,3,4,5,6-HEXACHLOROCYCLOHEXANE (BHC)
—k-MERCAPTURIC ACIOS
y-2,3,4,5,6-PENTACHLOROCYCLOHEXENE
TETRACHLOROCYCLOHEXENOL
2,3,4,5,6-
PENTACHLOROCYCLOHEXENE
TETRACHLOROPHENOL
PENTACHLOROPHENOL
TRICHLOROPHENOL
TRICHLOR08ENZENE
<2CI
DICHLOROPHENOL
DICHLORO8ENZENE
Figure A.8.2. Proposed metabolic pathway for lindane in rats.
Source: Adapted from Engst et al., 1976, Figure 12, p. 113. Reprinted
by courtesy of Marcel Dekker, Inc.
Pentachlorophenol appears to accumulate in the tissues of aquatic
organisms exposed to ambient levels of the substance. The extent to
which pentachlorophenol bioconcentrates or biomagnifies in aquatic food
chains is unknown and this question warrants further research.
In summary, the available data on environmental contamination by
chlorophenols preclude the formulation of definitive conclusions regard-
ing the effects of these compounds on humans. The extent to which the
wide distribution of chlorophenols, particularly pentachlorophenol,
affects human health and welfare and the integrity of the environment
requires further investigation so that policymakers as well as the public
can be fully informed concerning the environmental impact of chlorophenol
use and can determine if additional regulatory measures are warranted.
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61
SECTION A.8
REFERENCES
Engst, R., R. M. Macholz, M. Kujawa, H. J. Lewerenz, and R. Plass. 1976.
The Metabolism of Lindane and Its Metabolites gamma-2,3,4,5,6-Penta-
chlorocyclohexene, Pentachlorobenzene, and Pentachlorophenol in Rats and
the Pathways of Lindane Metabolism. J. Environ. Sci. Health Bll(2):95-117,
Marcel Dekker, Inc., New York.
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PART B
2-CHLOROPHENOL AND 2,4-DICHLOROPHENOL
63
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B. 1 SUMMARY
E.I.I DISCUSSION OF FINDINGS
2-Chlorophenol, a light ambers-colored liquid at room temperature,
has a pungent medicinal odor. It is slightly soluble in water but it is
readily soluble in organic solvents and aqueous alkaline solutions. The
compound possesses a substantial vapor pressure and readily volatilizes
with steam, even from aqueous alkaline solutions. This characteristic
may contribute to its distribution in the environment. Most 2-chloro-
phenol produced is used as an intermediate in the synthesis of higher
chlorophenols. It has been used as a polymer intermediate in the manu-
facture of fire-retardant varnishes and as an aminizing agent for cotton
fabric to provide rot resistance and crease recovery.
2-Chlorophenol may be converted to higher chlorophenols (particularly
2,4- and 2,6-dichlorophenol) during chlorination of drinking water or
wastewater. The resulting chlorophenols contribute significantly to the
objectionable phenolic odor and taste of water, making it unfit for human
consumption. Another important reaction of 2-chlorophenol is increasing
ionization of the compound at pH values above its pK value. The result-
ing ions may form salts with alkali metals and these compounds, being
more soluble in water, may be transported more easily in the ecosystem.
2,4-Dichlorophenol exists as colorless crystals at room temperature.
Like 2-chlorophenol, its solubility in water is very low, but its solubil-
ity in organic solvents and in aqueous alkaline solutions is high. 2,4-
Dichlorophenol is much less volatile than 2-chlorophenol, and transport
through the atmosphere is less likely to occur. 2,4-Dichlorophenol serves
primarily as a starting material in the manufacture of other compounds,
particularly pesticides. The most important use of 2,4-dichlorophenol is
in the production of 2,4-dichlorophenoxyacetic acid (2,4-D). Other com-
monly used pesticides such as sesone and nitrofen are also manufactured
from 2.4-dichlorophenol. Widespread use of these pesticides may contrib-
ute to 2,4-dichlorophenol contamination of the environment as a result of
pesticide degradation. Some metal salts of 2,4-dichlorophenol have been
used as germicides and antiseptics.
2,4-Dichlorophenol undergoes reactions similar to those of 2-chloro-
phenol in the environment. Dichlorophenols have been implicated as com-
pounds partially responsible for the objectionable phenolic odor and taste
in water. In addition, 2,4-dichlorophenol may be chlorinated during chlo-
rination of drinking water or wastewater, resulting in the formation of
higher chlorophenols which are more potent in causing objectionable taste
and odor. Solubility and sorption properties of 2,4-dichlorophenol may
be altered by pH-ionization effects.
A number of analytical techniques have been used in the identifica-
tion and quantification of 2-chlorophenol and 2,4-dichlorophenol in samples
of soil, water, and biological tissues. Gas-liquid chromatography (employ-
ing either electron-capture or flame-ionization detectors) appears to be
65
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66
the best method for separation, identification, and quantification of low
levels of chlorophenols found in a wide variety of environmental samples.
Colorimetric methods, although simple and rapid, lack specificity and thus
are only useful for gross determination of chlorophenols. Other methods
of detection, including thin-layer chromatography, infrared and ultravi-
olet spectrophotometry, and mass spectrometry, provide specific identifi-
cation but are useful only for determination of relatively large
concentrations.
Both 2-chlorophenol and 2,4-dichlorophenol are bactericidal, fungi-
cidal, and algicidal. 2,4-Dichlorophenol has been used in the past as a
bactericide, but its use has now been supplanted by more effective agents..
2,4-Dichlorophenol is generally a more effective microbicide than 2-chlo-
rophenol. It has been proposed that the bactericidal action of these
compounds stems from effects on the lip ids of bacteria, causing cell wall
damage, changes in permeability, and perhaps enzyme inhibition. In gen-
eral, bactericidal and algicidal potency increases with increased chlorine
substitution of the parent phenol up to the trichlorophenol isomers.
2-Chlorophenol and 2,4-dichlorophenol are not highly toxic to plants.
2,4-Dichlorophenol may appear in vascular plants following application of
2,4-D. Large amounts of 2,4-dichlorophenol are sorbed by the roots of
oats and soybeans grown in 2,4-dichlorophenol-treated soils or nutrient
solutions. Although small quantities of the compound are detected in the
shoots of treated plants, transport does not appear to occur readily.
2,4-Dichlorophenol does not concentrate in the seeds of soybeans or oats.
2,4-Dichlorophenol applied to leaves does not appear to be translocated.
Biotransformation of lower chlorophenols by vascular plants is not
well studied. It has been proposed that conjugation specifically by
glycoside formation and immobilization of the compound may occur when
2-chlorophenol or 2,4-dichlorophenol are absorbed by plants. A glycoside
of 2-chlorophenol, g-0-chlorophenyl gentiobioside, has been isolated from
the roots of tomato plants grown in culture media containing 2-chloro-
phenol. The mechanism of toxic action of lower chlorophenols to vascular
plants is not well studied. 2-Chlorophenol and 2,4-dichlorophenol are
capable of inhibiting certain plant enzyme systems. No information
exists on the phytotoxic effects of 2-chlorophenol in vascular plants,
but 2,4-dichlorophenol has been shown to inhibit root growth in flax
seedlings, cell expansion in wheat coleoptiles, and the growth-stimulating
effect of indoleacetic acid in wheat. 2,4-Dichlorophenol clearly induces
increased frequency of mitotic abnormalities in the European broad bean.
Effects on the productivity of treated plants are minimal, however, and
the significance of the mitotic effect to domestic and wild plants is
not known.
Biological impacts of 2-chlorophenol and 2,4-dichlorophenol in birds
and mammals are generally unknown. Sheep and cattle ingesting 2,4-D in
large amounts generally exhibited a weakened condition. Small doses were
well tolerated with no detectable adverse effect. These animals metabo-
lized 2,4-D to form 2,4-dichlorophenol, which was detected in the liver
and kidney. 2,4-Dichlorophenol was retained in the liver over a one-week
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67
withdrawal. The significance of 2,4-dichlorophenol in producing clinical
toxicity in this study is unknown. 2,4-Dichlorophenol has also been
detected in laying hens administered nemacide. Relatively high levels
of the compound were detected in the liver and the egg yolk, but no resi-
dues were found in the fat or in breast muscle. Substantial levels of
2,4-dichlorophenol were detected in the liver for as long as 21 days fol-
lowing removal from treated feed. No signs of toxicity were noted in
the hens.
2-Chlorophenol is toxic to aquatic organisms. Median lethal toler-
ance limits for fish range from 2.6 to 8.2 mg/liter. 2,4-Dichlorophenol
affects oxygen consumption and cell division in fertilized sea urchin
eggs at a concentration of 10 mg/liter. The 48-hr median lethal toler-
ance limit of 2,4-dichlorophenol to daphnia is reportedly 2.6 mg/liter.
The mechanism of action of these compounds in aquatic organisms is spec-
ulative. Both compounds can inhibit oxidative phosphorylation in higher
animals, and it has been proposed that this effect also contributes to
toxicity in aquatic organisms.
2-Chlorophenol and 2,4-dichlorophenol are corrosive to the skin of
humans and experimental animals. Both compounds may be absorbed directly
through the skin, but 2-chlorophenol is more easily absorbed by this
route. 2-Chlorophenol administered subcutaneously, intravenously, intra-
peritoneally, or orally is toxic to experimental animals. Median lethal
doses for 2-chlorophenol range from 100 to 800 mg/kg body weight. Oral,
intraperitoneal, or subcutaneous administration of 2,4-dichlorophenol to
experimental animals results in LDSO values of 430 to 1730 mg/kg. Chronic
feedings of 2,4-dichlorophenol to mice at levels as high as 100 mg/kg
daily had no discernable effect over a six-month period. 2-Chlorophenol
has not been chronically administered to experimental animals. No docu-
mented cases of human poisoning by either compound were found.
2-Chlorophenol and 2,4-dichlorophenol are apparently excreted pri-
marily in the urine, and the formation of conjugates (particularly with
sulfuric and glucuronic acids) has been demonstrated. 2,4-Dichlorophenol
and its conjugates have been detected in the urine of experimental animals
administered y-1,2,3,4,5,6-hexachlorocyclohexane (lindane). Elimination
of 2,4-dichlorophenol following its production from other organic sub-
stances appears to be relatively rapid.
As mentioned above, 2,4-dichlorophenol appears in mammals as a result
of metabolism of other organic compounds (e.g., lindane and nemacide).
Similarly, 2-chlorophenol has been detected as a metabolite of organic
compounds, including chlorobenzene isomers. Exposure of animals or humans
to these precursor compounds is more probable than direct exposure to
either 2-chlorophenol or 2,4-dichlorophenol. Neither compound is used
widely, and exposure is therefore likely to be limited to workers in the
manufacturing industry. Exposure of the general population is more likely
to occur through contact with compounds such as lindane or nemacide, which
have been widely used as pesticides.
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68
No physiological or biochemical role for 2-chlorophenol or 2,4-
dichlorophenol in any biological system has been found; therefore, it is
unlikely that a nutritional requirement for either of these compounds
exists. The mechanism of toxic action of 2-chlorophenol and 2,4-dichlo-
rophenol on higher organisms is speculative. Both compounds have inhib-
ited oxidative phosphorylation in in vitro tests. They are relatively
weak uncouplers of oxidative phosphorylation, but if dosages are high
enough, this effect can cause death. 2,4-Dichlorophenol also affects
various enzyme systems in the cell.
Experimental animals fatally poisoned by 2-chlorophenol usually
exhibit tremors and convulsions, but symptoms of 2,4-dichlorophenol poi-
soning are vague and do not include nervous effects. The biological basis
for these different clinical pictures is not known.
2-Chlorophenol and 2,4-dichlorophenol promote the appearance of benign
and malignant skin tumors in mice following a single initiating dose of
the compound dimethyIbenzanthracene. No evidence exists, however, that
either compound causes tumors in the absence of an initiator. Despite
this fact and the questionable hazard to humans, protracted skin contact
is not recommended because of the potential for tumor formation and because
both compounds are primary skin irritants.
Only one study has suggested that 2,4-dichlorophenol may have adverse
effects in humans. Acquired chloracne and porphyria (indicative of some
liver damage) have been reported among workers involved in the manufacture
of 2,4-dichlorophenol and 2,4,5-trichlorophenol. The wide variety of chem-
icals to which these workers were exposed precludes an absolute identifi-
cation of the responsible substance, but available evidence indicates that
tetrachlorodibenzo-p-dioxin was involved.
Monitoring data on the presence of 2-chlorophenol or 2,4-dichloro-
phenol in air, water, or soil are not available. The moderate volatility
of these compounds suggests that volatilization is a mechanism for dis-
persing the chemicals into the atmosphere. Incineration might also gen-
erate volatile products to the atmosphere through the burning of containers
and trash containing chlorophenols. Movement, persistence, and fate of
the compounds in the atmosphere are not understood. Possibly, photode-
composition contributes to their dissipation.
Contamination of water with 2-chlorophenol and 2,4-dichlorophenol
could arise from (1) chlorination of phenols present in natural water and
in primary and secondary effluents of waste treatment plants, (2) direct
addition of the chemicals from industrial sources or as contaminants or
degradation products of 2,4-D used for aquatic weed control, and (3) wet
and dry atmospheric fallout. Additionally, runoff from agricultural land
where 2,4-D or similar herbicides are used could be an important source
of chlorophenols in aquatic environments. 2-Chlorophenol and 2,4-dichloro-
phenol may be transported in aquatic environments in the dissolved form,
associated with suspended matter and bottom sediments, or absorbed in bio-
logical tissues. Both 2-chlorophenol and 2,4-dichlorophenol appear to
dissipate rather rapidly in aquatic systems. Microorganisms apparently
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69
play a crucial role in the degradation of these compounds, although it
is known that 2,4-dichlorophenol undergoes photolysis when exposed to
ultraviolet light. Thus, solar radiation may contribute to the degrada-
tion of the compound in water of sufficient clarity to allow penetration
of solar radiation.
Neither 2-chlorophenol nor 2,4-dichlorophenol appear to pose a ser-
ious hazard to waste treatment facilities which are normally exposed to
these compounds; they are readily degraded by activated sludge and by
microbial populations in aeration lagoon effluent. Some investigations
have shown that a specialized microflora is necessary for rapid dissipa-
tion of the compounds. Additionally, limnological factors such as oxygen
depletion affect degradation rates. Some hazard therefore exists if
wastes containing high levels of these compounds are discharged to an
unacclimated body of water or sewage treatment facility. 2-Chlorophenol
and 2,4-dichlorophenol are apparently totally degraded under optimum
conditions within five days; pH, temperature, and concentration of the
compounds affect the speed of degradation.
The primary source of soil contamination by chlorophenols is probably
through the application of 2,4-D and its derivatives on croplands, although
atmospheric fallout or washout may also contribute to contamination. The
herbicide 2,^-D and its derivatives are used widely. In 1971, U.S. farmers
applied almost 16 million kilograms of 2,4-D, which represents 15% of all
organic herbicide usage. 2,4-Dichlorophenol may be applied directly to
croplands as an impurity in 2,4-D preparations. Amounts ranging from 70
to 4500 mg/kg of 2,4-D have been reported. Therefore, 2,4-dichlorophenol
(and possibly 2-chlorophenol) generated from herbicide applications has
the potential to accumulate depending on environmental conditions and the
presence or absence of microorganisms capable of its further degradation.
Groundwater contamination with 2,4-D and 2,4-dichlorophenol has been re-
ported in two serious cases. Wastewaters containing 2,4-D and 2,4-dichlo-
rophenol were dumped into local sewage systems with the resultant phenolic
tastes and odors downstream in shallow wells; the problem persisted for
three years. In Colorado, 2,4-D was manufactured and wastes were dis-
charged into lagoons from 1943 to 1957. Groundwater contamination was
first reported in 1951 when crops were damaged by irrigation well water.
Seven to eight years were required for the contaminant to migrate 5.6 km
and to affect an area of 16.8 km2.
Present data indicate that 2-chlorophenol and 2,4-dichlorophenol are
not bound tightly to soil and that sorption, when it occurs, is likely to
be weak. Desorption and downward movement through the soil profile may
occur; however, contamination of groundwater is expected to occur only
when highly concentrated solutions are applied to soil. Evidence suggests
that microorganisms found commonly in soil are capable of degrading both
2-chlorophenol and 2,4-dichlorophenol. Microbial decomposition appears
to be the dominant dissipation mechanism for these compounds in soil.
Percolation experiments have indicated that 2-chlorophenol may be degraded
within ten days, and 2,4-dichlorophenol is similarly short-lived in soils.
Both bacterial and fungal species are capable of degrading chlorophenols,
and a number of bacterial species may utilize the lower chlorophenols as
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70
their sole source of organic carbon and energy. Whether or not fungal
strains are capable of utilizing lower chlorophenols as a sole carbon
source is not known.
Food contamination with 2-chlorophenol and 2,4-dichlorophenol appears
to be minimal; thus, transfer to humans through the food chain is appar-
ently remote. The direct exposure of humans to these chemicals during
manufacture constitutes the major hazard. Widespread distribution and
accumulation of 2-chlorophenol and 2,4-dichlorophenol in the environment
is unlikely because these compounds tend to degrade readily in soil and
aquatic systems. No data are available, however, to conclusively prove
these contentions. More definitive investigations are needed to assess
the environmental hazards associated with the usage of the compounds. Ac-
cumulation in fish and other aquatic organisms exposed to waters contami-
nated with the chemicals has not been investigated. The widespread use
of chlorination for waste treatment and water purification also must be
questioned. The presence of lower chlorophenols may allow the formation
of the more dangerous highly chlorinated phenols in wastewater or drinking
water.
B.I.2 CONCLUSIONS
1. 2-Chlorophenol can be converted to higher chlorophenols (including
2,4-dichlorophenol) during chlorination of drinking water or waste-
water, imparting objectionable phenolic odor and taste to the water.
2. 2,4-Dichlorophenol may be converted to higher chlorophenols during
chlorination of drinking water or wastewater.
3. Gas-liquid chromatography is the best method for separation, identi-
fication, and quantification of low levels of 2-chlorophenol and
2,4-dichlorophenol in environmental samples.
4. 2-Chlorophenol and 2,4-dichlorophenol are bactericidal, fungicidal,
and algicidal.
5. 2-Chlorophenol and 2,4-dichlorophenol are not highly toxic to plants,
terrestrial animals, or humans.
6. 2,4-Dichlorophenol may appear in domestic animals following absorp-
tion of the chemically related phenoxyalkanoic herbicides.
7. 2-Chlorophenol and 2,4-dichlorophenol are moderately toxic to aquatic
organisms; LCSO values range from 2.6 to 8.2 mg/liter.
8. Elimination of 2-chlorophenol or 2,4-dichlorophenol occurs primarily
through the urine, and the presence of sulfuric and glucuronic acid
conjugates has been reported.
9. Chronic toxicity of 2-chlorophenol and 2,4-dichlorophenol has not
been documented.
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71
10. 2-Chlorophenol and 2,4-dichlorophenol promote the appearance of tumors
in mice following an initiating dose of dimethylbenzanthracene, but
neither compound causes tumors in the absence of an initiator.
11. Relatively rapid degradation of 2-chlorophenol and 2,4-dichlorophenol
occurs in aquatic systems, including activated sludge and aeration
lagoons, but a specialized microflora is necessary for optimum deg-
radation rates of the compounds.
12. The primary source for soil (and perhaps water) contamination by
lower chlorophenols is likely degradation of chemically related
phenoxyalkanoic herbicides such as 2,4-D.
13. 2-Chlorophenol and 2,4-dichlorophenol are not tightly bound to soil
particles, and groundwater contamination may result when large amounts
(or highly concentrated solutions) of the compounds are dumped into
local sewage systems or retained in waste lagoons.
14. Microbial decomposition readily dissipates 2-chlorophenol and 2,4-
dichlorophenol from soils.
15. Food contamination with 2-chlorophenol and 2,4-dichlorophenol is
minimal and transfer to humans through the food chain appears to
be remote.
16. The possible accumulation of 2-chlorophenol and 2,4-dichlorophenol
by fish and other aquatic organisms has not been investigated.
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B.2 CHEMICAL AND PHYSICAL PROPERTIES AND ANALYSIS
B.2.1 PHYSICAL PROPERTIES
2-Chlorophenol is a light amber-colored liquid at room temperature
and has a pungent, medicinal odor. It is slightly soluble in water but
is readily soluble in several organic solvents and aqueous caustic alka-
line solutions. It volatilizes with steam, even from aqueous alkaline
solutions. Table A.2.1 lists the important physical properties of
2-chlorophenol.
2,4-Dichlorophenol exists as colorless crystals at room temperature.
It has an unpleasant and persistent odor similar to iodoform. Its solu-
bility in water is very low, although it is easily soluble in many organic
solvents and is also soluble in aqueous alkaline solutions. This compound
generally behaves as a weak acid and volatilizes with steam, but unlike
2-chlorophenol, it is not volatile from aqueous alkaline solutions. Some
of the important physical properties of 2,4-dichlorophenol are given in
Table A.2.1.
2,4-Dichlorophenol has higher boiling and melting points than 2-
chlorophenol. This wide variation in boiling points is useful in separat-
ing the two compounds by fractional distillation. Another factor that can
be utilized in separating the monochlorophenol from the dichlorophenol is
volatilization. Both chemicals are volatile, but 2-chlorophenol has a much
higher vapor pressure (1 mm Hg at 12.1°C) than 2,4-dichlorophenol (1 mm Hg
at 53°C), making it more susceptible to volatilization.
B.2.2 MANUFACTURE
2-Chlorophenol can be synthesized by diazotization of 2-chloroaniline,
direct chlorination of phenol, or hydrolysis of 1,2-dichlorobenzene (Doedens,
1963). The most commonly used process in the commercial production of 2-
chlorophenol is direct chlorination of phenol. Direct chlorination is
carried out by passing gaseous chlorine into molten phenol at temperatures
of 50°C to 150°C. This process leads to the formation of both 2- and 4-
chlorophenol and the isomers are separated by fractional distillation
because the difference in boiling points is greater than 40°C. Most of
the 2-chlorophenol used commercially in the United States is recovered as
a by-product from the manufacture of 4-chlorophenol by direct chlorination
of phenol.
The production of 2,4-dichlorophenol by direct chlorination of phenol
with 2 moles of chlorine was patented by Imperial Chemical Industries in
1948 (Doedens, 1963). This method involves passing chlorine into molten
phenol at 80°C to 100°C until a product with a melting point of 34°C to
36°C is obtained. The reaction results in the formation of small amounts
of 2,6-dichlorophenol and 2,4,6-trichlorophenol. 2,4-Dichlorophenol can
be isolated in a yield of 80% to 90%. Another method of preparing 2,4-
dichlorophenol is the further chlorination of 2- or 4-chlorophenol. Chlo-
rination of 2-chlorophenol yields a mixture of 2,4- and 2,6-dichlorophenol.
72
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73
High-purity 2,4-dichlorophenol may be manufactured through chlorination
of 4-chlorophenol by controlling the chlorine ratio to avoid formation of
trichlorophenols.
B.2.3 USES
Most of the 2-chlorophenol produced in the United States is used as an
intermediate in the synthesis of higher chlorophenols (Doedens, 1963). It
can be used as a polymer intermediate in the manufacture of fire-retardant
varnishes and as an aminizing agent for cotton fabric to provide rot re-
sistance and crease recovery. Its use in fire-retardant products may now
be insignificant because bromide compounds have largely been utilized as
replacements. Although 2-chlorophenol possesses pesticidal and bacteri-
cidal properties, its use has been supplanted by more effective higher
chlorophenols (Dow Chemical Company, 1977).
2,4-Dichlorophenol is primarily used as a starting material in the
manufacture of pesticides (Doedens, 1963; Dow Chemical Company, undated).
Its most important use is in the production of 2,4-dichlorophenoxyacetic
acid (2,4-D). This compound and its derivatives have been used widely as
hormone-type herbicides. Other herbicides produced with 2,4-dichlorophenol
as an intermediate are sesone (sodium 2,4-dichlorophenoxy-ethyl sulfate)
and nitrofen (2,4-dichlorophenyl 2-nitrophenyl ether). The dialkyl phos-
phorothioates and aryl and alkyl sulfonates of 2,4-dichlorophenol have been
used as insecticides, nematocides, and miticides. For example, nemacide
[0-(2,4-dichlorophenyl)0jC>-diethyl phosphorothioate] is used both as an
insecticide and nematocide, and Genite-EM-923 (2,4-dichlorophenyl benzene-
sulfonate) is used as a miticide. The metal salts of 2,4-dichlorophenol
are used as germicides and antiseptics. 2,4-Dichlorophenol also has been
used as a raw material to form polyether carbonate and polyester films
(Dow Chemical Company, undated).
B.2.4 CHEMICAL REACTIVITY
2-Chlorophenol can undergo several chemical reactions (Doedens, 1963).
Because the phenolic group activates the aromatic ring toward electrophilic
substitution, many ring-substitution reactions are possible. Among the
more important ones are further chlorination to 2,4- and 2,6-dichlorophenol,
bromination, iodation, and nitration to monosubstituted and disubstituted
derivatives. Condensation reactions of 2-chlorophenol with formaldehyde
produce phenolic resin intermediates or methylene bridged polymers. The
phenolic group behaves like phenol in etherification reactions, Claisen
condensations, allylic rearrangements, and esterification with phosphorous
oxychlorides. Under proper conditions, the hydroxyl group may ionize, and
in the presence of alkali metals, metallic salts are formed.
Substitution occurs in the aromatic ring of 2,4-dichlorophenol
(Doedens, 1963). It undergoes halogenation and nitration readily with
substitution in the 6 position. Further chlorination of 2,4-dichlorophenol
yields 2,4,6-trichlorophenol. Reaction with formaldehyde yields condensa-
tion products that are methylene bridged dimers. The phenolic group of
2,4-dichlorophenol reacts with acyl chlorides, ketenes, alkyl halides,
-------
74
sulfonyl halides, and oxides. Salt formation is accomplished easily by
reaction with alkali metals.
Perhaps the most important reaction of the phenolic group of 2,4-
dichlorophenol is in the synthesis of 2,4-D. Commercial production of
2,4-D involves reacting 2,4-dichlorophenol with monochloroacetic acid in
the presence of sodium hydroxide. Other pesticides are also produced by
reaction of the phenolic group. Reactions of chloronitrobenzene, ethyl
sodium sulfate, and diethyl chlorothiophosphate with 2,4-dichlorophenol
produce nitrofen, sesone, and nemacide respectively.
Most of the chemical reactions described can only be performed under
controlled laboratory conditions. Two reactions may be particularly im-
portant in the environment — the conversions of 2-chlorophenol to 2,4- and
2,6-dichlorophenol and of 2,4-dichlorophenol to 2,4,6-trichlorophenol dur-
ing chlorination of drinking water or wastewater. Dichlorophenols have
been implicated as the compounds contributing largely to the objectionable
phenolic odor and taste of water (Burttschell et al., 1959; Baker, 1965).
Burttschell et al. (1959) reported that the threshold odor and taste con-
centrations for 2,4-dichlorophenol range from 2 to 8 yg/liter. Because
2-chlorophenol and 2,4-dichlorophenol have some weak acid characteristics,
they can be ionized slowly in aqueous solutions. At pH values near or
above their pKa values, they may exist in the ionized form and may form
salts in the presence of high concentrations of alkali metals. The salt
forms of these chlorophenols are more soluble in water, which may favor
their transport in solution in the ecosystem. The molecular form (non-
ionized) of the two compounds may prevail at low pH values. The reactive
form of the compounds (i.e., ionized or molecular) could play a role in
the sorption of chlorophenols in soil, sediments, or particulate matter.
B.2.5 TRANSPORT AND TRANSFORMATION IN THE ENVIRONMENT
Transport mechanisms and transformation of 2-chlorophenol and 2,4-
dichlorophenol in air, soil, and aquatic environments are discussed in
detail in Section B.7. The summary presented below gives a perspective
on the possible relationships of the physical and chemical properties of
the chemicals to their interactions with different segments of the
environment.
B.2.5.1 Air
Both 2-chlorophenol and 2,4-dichlorophenol are highly volatile, and
volatilization may be the major dispersal mechanism of the chemicals in
the atmosphere. However, because monitoring data indicating their pres-
ence are not available, transportation and transformation mechanisms in
the atmosphere cannot be determined.
B.2.5.2 Aquatic Environment
2-Chlorophenol and 2,4-dichlorophenol may exist in the aquatic envi-
ronment in the dissolved form, may be associated with suspended matter and
bottom sediments, or may be absorbed in biological tissues. Metal salts
-------
75
of these compounds have greater water solubility, and if they are intro-
duced or formed in situ, they would exist primarily in the dissolved form.
Because chlorophenols are weak acids, they tend to ionize, depending on
the pH of the system. They are nonionized in aqueous solution with pH
lower than 5 and become increasingly dissociated as the pH rises (Cserjesi,
1972). The degree of dissociation could determine their sorption. Limited
information indicates that they may not be sorbed significantly by colloids
present in the aquatic environment. Hydrological factors such as current
pattern and mixing and degradation and migration of organisms affect the
movement of these chemicals.
A few investigations indicate that the dissipation of 2-chlorophenol
(Ettinger and Ruchhoft, 1950) and 2,4-dichlorophenol (Aly and Faust, 1964)
is largely microbiological. Persistence appears to be short, but limno-
logical factors such as oxygen deficiency may delay degradation (Aly and
Faust, 1964). Microorganisms found in activated sludge and waste lagoons
degrade the two chemicals rather readily (Sidwell, 1971; Nachtigall and
Butler, 1974).
2,4-Dichlorophenol undergoes photolysis when it is exposed to ultra-
violet light (Aly and Faust, 1964). This process may be an important natu-
ral mechanism for its removal from water. Whether the amount of ultraviolet
light from solar radiation is sufficient to cause photolytic reaction under
natural conditions has not been determined.
B.2.5.3 Soils
The mobility of 2-chlorophenol and 2,4-dichlorophenol in soils may be
influenced largely by sorption. The extent of sorption determines whether
the chemicals are carried with soil during erosion or move through the soil
profile during infiltration. Aly and Faust (1964) reported that only a
small amount of 2,4-dichlorophenol was sorbed by clay minerals. Soil or-
ganic matter plays a major role in the sorption of many organic pesticides
(Weber, 1972). It is generally accepted that although acidic pesticides
such as 2,4-D are sorbed by organic matter, the sorption bond strength is
weak. 2,4-Dichlorophenol is probably sorbed in a similar manner as 2,4-D,
which makes it potentially susceptible to downward movement in soil with
water.
There is strong evidence for the participation of microorganisms in
the dissipation of 2-chlorophenol and 2,4-dichlorophenol in soils. Bac-
teria isolated from soils, including those known to degrade phenoxyacetic
herbicides, are capable of metabolizing the compounds (Bollag, Helling, and
Alexander, 1968; Evans et al., 1971; Spokes and Walker, 1974). Limited
information indicates short persistence of the chemicals in soil (Walker,
1954; Alexander and Aleem, 1961).
B.2.6 ANALYSIS v
Because the sample preparation, isolation, and determination of
2-chlorophenol and 2,4-dichlorophenol are the same, their analyses will
be discussed concurrently.
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76
B.2.6.1 Sampling, Storage, and Preservation
One of the most important considerations in the analysis of chloro-
phenols is sample collection, handling, and storage. The importance of
proper sampling and preservation is underscored by the fact that present
methods allow analyses at the nanogram level. Efforts should be made to
eliminate contamination of samples and degradation of compounds. Infor-
mation dealing specifically with chlorophenols does not exist; however,
sampling and storage information for pesticides in Standard Methods for
the Examination of Water and Wastewater (Rand, Greenburg, and Taras, 1976)
and in a report by Chesters, Pionke, and Daniel (1974) may provide useful
guidelines.
In sampling air, water, soil, and biological tissues, representative
samples must be obtained. For any medium sampled, the reaction of the
compounds in relation to the characteristics of the medium should be re-
viewed, and the physical and chemical characteristics of the sampling area
should be investigated. The number of samples collected depends on the
area and size of the medium to be sampled and the objectives of the study.
Glass or plastic containers can be used to hold samples, but samples ana-
lyzed for organic compounds are best held in glass containers to prevent
adsorption on the walls of the container.
Ideally, samples should be extracted and analyzed immediately after
collection. If analysis is delayed, samples must be preserved to prevent
biochemical and chemical changes. The commonly used method for samples
not analyzed upon receipt is storage at 2°C to 4°C or at freezing temper-
atures. Chemical preservatives should be used only when they will not
interfere with the ultimate analysis. Acidification with H3PO<, and CuSOi,
treatment followed by refrigeration at 5°C to 10°C has been recommended
for the preservation of wastewater samples for phenol analysis (Rand,
Greenberg, and Taras, 1976).
B.2.6.2 Sample Preparation for Analysis
Regardless of the kind of sample analyzed for 2-chlorophenol and 2,4-
dichlorophenol, some form of sample preparation is necessary to obtain a
reliable and accurate determination. This preparation involves isolation
and cleanup methods (Table B.2.1). Isolation methods include blending,
liquid-liquid extraction, and distillation. Direct-aqueous-injection gas-
liquid chromatography techniques have been reported (Baker, 1966; Baird
et al., 1974), but this method is limited to "clean" water samples. Com-
plex samples such as soils and biological tissues need vigorous isolation
and cleanup processes prior to chlorophenol determination.
The extraction technique used depends on the kind of samples analyzed.
For biological tissues (i.e., plant and animal tissues), blending with sol-
vent or hydrolysis with acid and alkali solutions prior to solvent extrac-
tion has been successful (Sherman, Beck, and Herrick, 1972; Steen et al.,
1974; Clark et al., 1975). Chlorophenols in aqueous samples such as urine,
milk, and bacterial cultures can be extracted directly after acidification
(Loos, Roberts, and Alexander, 1967; Bjerke et al., 1972; Kuhihara and
Nakajima, 1974; Nakagawa and Crosby, 1974; Rand, Greenberg, and Taras,
-------
77
1976). In some instances, steam distillation with or without further
extraction is sufficient (Loos, Roberts, and Alexander, 1967; Zigler and
Phillips, 1967; Evans et al., 1971; Rand, Greenberg, and Taras, 1976).
Fritz and Willis (1973) reported the separation of phenolic compounds, in-
cluding 2-chlorophenol and 2,4-dichlorophenol, using high-pressure liquid
chromatography with a polyacrylate resin column. The isolation and con-
centration of phenolic contaminants in water has also been accomplished
by freeze-drying (Baker, 1966) and by adsorption on activated carbon fol-
lowed by chloroform extraction (Eichelberger, Dressman, and Longbottom,
1970). Among the organic solvents used for the extraction of 2-chlorophe-
nol and 2,4-dichlorophenol are hexane, ethyl acetate, ethyl ether, diethyl
ether, carbon disulfide, methylene chloride, benzene, and petroleum ether.
The ultimate objective of sample preparation is to eliminate inter-
ferences so that samples are adequately clean for the determination and
identification of the compound of interest. This procedure is particu-
larly important with very low levels of 2-chlorophenol and 2,4-dichloro-
phenol in the environment. Liquid-liquid extraction and distillation could
provide a means of eliminating interferences and concentrating samples.
However, these processes are nonspecific, and other organic compounds may
be coextracted or codistilled with the chlorophenols, causing interference
problems; therefore, further cleanup must be performed on the extract or
distillate. Cleanup methods are indicated in Table B.2.1. The most com-
monly used method is column chromatography (Bjerke et al., 1972; Shafik,
Sullivan, and Enos, 1973; Steen et al., 1974). In this technique, extracts
are passed through silica or alumina (Florisil) columns and the compound
is eluted by organic solvents such as ether and/or hexane-benzene combina-
tions. Shafik, Sullivan, and Enos (1973) concluded that silica gel column
chromatography not only provided a clean sample for gas chromatographic
analysis, but also conveniently separated the halogenated phenols from
nitrophenols by varying the concentration of the eluting solution. Thin-
layer chromatography also has been used for the purification of extracts
(Kurihara and Nakajima, 1974).
B.2.6.3 Determination and Identification
Methods for detection of 2-chlorophenol and 2,4-dichlorophenol in
environmental samples include colorimetry, chromatography, ultraviolet
and infrared spectrophotometry, and mass spectrometry (Table B.2.1). The
classic technique employed in the analysis of chlorophenol in water is
the 4-aminoantipyrine colorimetric method (Ettinger, Ruchhoft, and Lishka,
1951; Faust and Aly, 1962; Rand, Greenberg, and Taras, 1976). This method
is quite sensitive and easy to use, but it is nonspecific because the ami-
noantipyrine reacts with several isomers of chlorophenols to produce the
same color. Thus, it is not suitable for distinguishing between 2-chlo-
rophenol and 2,4-dichlorophenol contained in a sample.
Chromatographic techniques offer excellent selective separation and
identification of chlorophenols. Paper chromatography was used by Loos,
Roberts, and Alexander (1967) and Evans et al. (1971) to separate 2-chlo-
rophenol and 2,4-dichlorophenol from bacterial cultures fed with 2,4-D.
Evans et al. (1971) detected 2-chlorophenol and 2,4-dichlorophenol on the
-------
TABLE B.2.1. METHODS OF DETERMINATION OF 2-CHLOROPHENOL AND 2,4-DICHLOROPHENOL IN SEVERAL SAMPLE MATERIALS
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Source
Aqueous solution of 2-chloro-
phenol, 2,4-dlchlorophenol,
and 2,4,5-trichlorophenol
2,4-Dichlorophenol, 2,4,5- and
2,4,6-trichlorophenol in
natural waters
2-Chlorophenol, 2,4-dichloro-
phenol, and 2,3,4,5-tetra-
chlorophenol In mixtures
of standard phenols
2-Chlorophenol, 2,4-dichloro-
phenol, and 2,4,6-trichlo-
rophenol in mixtures of
standard chlorophenols
2,4-Dichlorophenol and 2,4,5-
trichlorophenol in rat urine
2,4-Dichlorophenol, 2,4,5- and
2,4,6-trichlorophenol, and
2,3,4,5- and 2,3,4,6-tetra-
chlorophenol in rabbit urine
Samples extracted with hexane and
dansyl derivatives of chloro-
phenols separated by thin-layer
chromatography
1000-ml acidified samples
extracted with petroleum ether
Phenols separated on a polyacry-
late resin column
1- to 5-ml samples hydrolyzed
with HjSOi. followed by extrac-
tion with ethyl ether and
ethylation with diazoethane;
eluted from silica gel column
with benzene-hexane
Extracted with diethyl ether;
concentrated by distillation;
eluted from silica gel column
successively with hexane and
benzene in hexane; eluate
extracted with NaOH
Fluorescence spectrometry
of dansyl derivatives
Two-dimensional thin-layer
chromatography at 1
yg/liter
High-pressure liquid chrom-
-^ atography with uv detector
Gas-liquid chromatography
Gas-liquid chromatography
using electron-capture
detector at levels of 0.1
mg/liter for 2,4-dichloro-
phenol and 0.01 ng/liter
for 2,4,5-trichlorophenol
Thermal conductivity gas-
liquid chromatography
In situ measurement of
fluorescence on thin-
layer chromatographic
plate; confirmation
analysis of deriva-
tives by mass spec-
troscopy
No interferences found
with coextractives
Elution of 21 phenols
described
Frei-HMusler, Frie, and
Hutzinger, 1973
Zigler and Phillips,
1967
Fritz and Willis, 1973
Barry, Vasishth,
Shelton, 1962
and
Comparable data obtained
by gas-liquid chroma-
tography and infrared
spectrometry
Silica gel chromatography Shafik, Sullivan, and
for cleanup; no inter- Enos, 1973
ference from impurities
eluted by benzene
00
Silica gel column for
cleanup; confirmation
by infrared and mass
spectrometry of chlo-
rophenols and/or anisole
derivatives; gas-liquid
chromatography with
electron-capture detec-
tor unsuitable because
of tailing and nonrepro-
ducible detector response
Karapally, Sana, and
Lee, 1973
(continued)
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TABLE B.2.1 (continued)
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Source
2,4-Dichlorophenol, 2,4,5- and
2,4,6-trichlorophenol in
mouse urine
2,4-Dichlorophenol and 2,4,5-
trichlorophenol in milk and
cream
2,4-Dichlorophenol arid 2,4,5-
trichlorophenol in sheep and
cattle tissues
2,4-Dichlorophenol in tissues
of legumes, grass, and small
grain plants
2-Chlorophenol and 2,4-dichlo-
rophenol in bacterial culture
2,4-Dichlorophenol in bacterial
culture
2,4-Dichlorophenol in bacterial
culture
Partitioned into benzene and
water; phenols determined in
both phases
Thermal conductivity gas-
liquid chromatography
Kurihara and Nakajima,
1974
10-g acidified sample extracted
with diethyl ether; eluted
through alumina column with
diethyl ether, followed by
series of extractions of eluate
with dilute NaOH and benzene
5-g sample acid hydrolyzed with
or without prior alkaline diges-
tion; codistilled with water,
followed by partitioning into
methylene chloride formation
of trimethylsilyl ether
Homogenized in methanol; extracted
with diethyl ether; eluted
through alumina column; eluate
extracted with NH«OH, acidified
and partitioned into benzene
Culture extracted with ether and
steam distilled
Culture fed with 2,4-D and centri-
fuged; supernatant containing
2,4-dichlorophenol acidified and
and extracted with CS2
Culture fed with 2,4-D and centri-
fuged; supernatant containing
2,4-dichlorophenol acidified
and steam distilled
Gas-liquid chromatography
using microcoulometric
or electron-capture
detector at levels of
0.05 ug/ml
Gas-liquid chromatography
at levels of 0.01 to 0.02
Ug/g
Gas-liquid chromatography
using electron-capture
detector at levels of
0.1 wg/g
Paper chromatography
Gas-liquid chromatography
using electron-capture
detector, infrared
spectrometry
Ultraviolet absorption
spectrometry
Bjerke et al., 1972
Thin-layer chromatog-
raphy used for puri-
fication of compounds;
enzyme hydrolysis of
water-soluble chloro-
phenol conjugates;
confirmation by mass
fragmentography
Column chromatography
for cleanup; NaOH or
benzene extraction of
eluate unnecessary
for 2,4,5-trichloro-
phenol; recovery >80%
Distillation for clean- Clark et al., 1975
up; no interference
of coextractives; alka-
line digestion increases
recovery; recovery >95%
Removal of plant pigments Steen et al., 1974
with methylene dichlo-
ride; further cleanup
on alumina column
Evans et al., 1971
Loos, Roberts, and
Alexander, 1967
Loos, Roberts, and
Alexander, 1967
vo
(continued)
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TABLE B.2.1 (continued)
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Source
2,4-Dichlorophenol in bacterial
culture
2,4-Dichlorophenol in egg yolk
2,4-Dichlorophenol in hen muscle
2,4-Dichlorophenol in hen liver
2-Chlorophenol and 2,4-dichlo-
rophenol in polluted water
2-Chlorophenol and 2,4-diehlo-
rophenol in wastewater
2-Chlorophenol, 2,4-dichloro-
phenol, 2,4,5- and 2,4,6-
trlchlorophenol in water
2-Chlorophenol and 2,4-dlchlo-
rophenol in surface water
2-Chlorophenol, 2,4-d ichloro-
phenol, and 2,4,6-trichlo-
rophenol in water
Formation of 2,4-dinltrophenol
with NaNO,
20-g sample blended in an ethanol,
H3SO,., and hexane mixture;
extracted with hexane-benzene
100-g sample blended in a hexane
and HjSOi. mixture; extracted
stepwlse with NaOH and hexane
25 g of liver ground and eluted
with hexane; eluate extracted
with CHjCN followed by hexane
100-ml sample steam distilled,
acidified, and extracted with
petroleum ether
Sample Injected directly
Chlorophenols absorbed on activated
carbon; adsorbates removed by
stepwise extraction with CHC19,
NaOH, and diethyl ether
Chlorophenols absorbed on activated
carbon; adsorbates removed by
extraction with CHClj and par-
titioned into acetone
Sample used to prepare 4-amlnoantl-
pyrine and p-nitrophenylazo dye
derivatives and extracted with
CHClj or ether •
Paper chromatography
Gas-liquid chromatography
using electron-capture
detector tit nanogram
levels
Gas-liquid chromatography
using electron-capture
detector at nanogram
levels
Gas-liquid chromatography
using electron-capture
detector at nanogram
levels
Reaction with 4-aminoanti-
pyrlne, colorimetry; 70
Ug/liter
Gas-liquid chromatography
using flame ionlzation
detector at submilligram
per liter levels
Gas-liquid chromatography
Formation of pentafluoro-
benzyl ether derivatives
followed by gas-liquid
chromatography using
electron-capture detec-
tor at subnanogram levels
Thin-layer chromatography
column for
cleanup
Cleanup accomplished
during distillation
and extraction
Filter to remove sus-
pended materials
which may interfere;
interference from
organics eliminated
by distillation
Florisil column for
cleanup
Derivative formation
eliminated cleanup
step
Loos, Roberts, and
Alexander, 1967
Sherman, Beck, and
Herrick, 1972
Sherman, Beck, and
Herrick, 1972
Sherman, Beck, and
Herrick, 1972
Rand, Greenberg, and
Taras, 1976
Baker, 1966; Baird et
al., 1974; Rand,
Greenberg, and Taras,
1976
Eichelberger, Dressraan,
and Longbottom, 1970
Kawahara, 1971
00
o
Aly, 1968
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81
chromatogram as the diazo dyes, and Loos, Roberts, and Alexander (1967)
detected the nitro derivative of 2,4-dichlorophenol. Estimation of chlo-
rophenols in water by thin-layer chromatography was reported (Zigler and
Phillips, 1967; Aly, 1968). Zigler and Phillips (1967) separated 2,4-
dichlorophenol from other chlorophenols using two-dimensional thin-layer
chromatography with AgN03 and 4-aminoantipyrine as the solvents. The use
of two chromogenic reagents provided a high degree of specificity. Aly
(1968) formed antipyryl and p-nitrophenylazo dye derivatives of 2-chloro-
phenol and 2,4-dichlorophenol before subjecting them to separation by thin-
layer chromatography. Better resolution of the two isomers was obtained
with the p-nitrophenylazo derivative. Paper chromatography and thin-layer
chromatography are simple and rapid and provide excellent resolution of
chlorophenols.
Gas-liquid chromatography, the most widely used technique of separat-
ing, identifying, and quantifying chlorophenols in various kinds of sam-
ples, employs either electron-capture or flame-ionization detectors (Table
B.2.1). Because gas-liquid chromatography is sensitive to nanogram levels,
it is adaptable for the quantitation of trace amounts of chlorophenols.
Although paper chromatography and thin-layer chromatography can resolve
chlorophenols satisfactorily, they are, at best, semiquantitative methods.
Gas-liquid chromatographic analysis of water and wastewater by direct aque-
ous injection (Baker, 1966; Baird et al., 1974) or by injection after ex-
traction and cleanup of samples (Eichelberger, Dressman, and Longbottom,
1970; Kawahara, 1971) has been described. Direct injection of water sam-
ples simplifies gas-liquid chromatographic analysis but requires removal
of interferences due to particulate matter and other organic compounds to
obtain good resolution and to prolong the life of the columns. Addition-
ally, injecting an aqueous medium may decrease the sensitivity of the
detector. Kawahara (1971) successfully determined 2-chlorophenol and 2,4-
dichlorophenol in surface waters in the presence of organic contaminants
such as mercaptans and organic acids by electron-capture gas-liquid chroma-
tography after forming the pentafluorobenzyl derivatives of the compounds.
Cleanup was not necessary because of the selective specificity and sensi-
tivity of the pentafluorobenzyl derivatives. 2,4-Dichlorophenol has been
identified by gas-liquid chromatography as one of the major metabolites in
the metabolism of 2,4-D in microorganisms (Loos, Roberts, and Alexander,
1967), animals (Bjerke et al., 1972; Clark et al., 1975), and plants (Steen
et al., 1974); of lindane in animals (Karapally, Saha, and Lee, 1973;
Kurihara and Nakajima, 1974); and of nemacide in hens (Sherman, Beck,
and Herrick, 1972).
Biological samples such as animal and plant tissues require more
extensive cleanup than water samples before they are suitable for gas-
liquid chromatography. Problems of poor resolution and tailing encountered
on some samples can be corrected by judicious selection of columns and type
of derivatization (Kawahara, 1971; Karapally, Saha, and Lee, 1973; Shafik,
Sullivan, and Enos, 1973; Baird et al., 1974). Columns reported to be
satisfactory for the separation of 2-chlorophenol and 2,4-dichlorophenol
include 4% dinonyl phthalate on 80/100-mesh Chromosorb G (Baird et al.,
1974), 10% FFAP (free fatty acid phase) on 60/80-mesh Chromosorb T (Baker,
1966; Kawahara, 1971), 20% Carbowax 20M-terephthalic acid on 60/80-mesh
-------
82
Chromosorb W-AW (Baker, 1966), 4% SE-30/6% QF-1 on 80/100-mesh Chromosorb
W-HP (Shafik, Sullivan, and Enos, 1973), 1.5% neopentyl glycol succinate
polyester on 60/80-mesh Chromosorb W-AW (Kurihara and Nakajima, 1974), 6%
DC-200 silicone oil on 80/100-mesh Gas-Chrom Q (Bjerke et al., 1972), 15%
diethylene glycol succinate/2% H3PO<, on 80/100-mesh Gas-Chrom P (Steen et
al., 1974), 3% OV-1 on 80/90-mesh Chromosorb W (Clark et al., 1975), and
3% OV-17 on 60/80-mesh Chromosorb W-AW-DMCS (Kurihara and Nakajima, 1974).
Cook and Spangelo (1974) reported the use of columns utilizing liquid crys-
tal stationary phases for the separation of m- and p-substituted isomeric
chlorophenols with similar boiling points and polarities. The ether deriv-
ative of chlorophenols formed with diazomethane or diazoethane is commonly
used to improve the resolution and to confirm the identity of 2-chlorophe-
nol and 2,4-dichlorophenol (Shafik, Sullivan, and Enos, 1973; Kurihara and
Nakajima, 1974). Shafik, Sullivan, and Enos (1973) obtained better gas
chromatographic resolution of more volatile chlorophenols by preparing the
ethyl rather than the methyl esters. Kawahara (1971) was able to deter-
mine subnanogram amounts of 2-chlorophenol and 2,4-dichlorophenol without
cleanup by reacting the compounds with <=-bromo-2,3,4,5,6-pentafluorotoluene
to form the pentafluorobenzyl esters. Cook and Spangelo (1974.) completely
separated the isomers when the chlorophenols were converted to substituted
phenyl n-alkyl ethers.
Ultraviolet and infrared spectrophotometry have also been used to
identify 2-chlorophenol and 2,4-dichlorophenol (Barry, Vasishth, and
Shelton, 1962; Loos, Roberts, and Alexander, 1967). However, these methods
are less sensitive than gas-liquid chromatography and are probably more
useful to confirm the identity of the compounds. Mass spectrometry is
also used for confirmatory analysis of chlorophenols (Frei-Hausler, Frei,
and Hutzinger, 1973; Safe, Jamieson, and Hutzinger, 1974), but this tech-
nique is complex and expensive. All of these methods require prior sepa-
ration of the compounds of interest before identification is made.
B.2.6.4 Assessment of Methods
Gas-liquid chromatography is the apparent method of choice for the
separation, identification, and quantification of low levels of chloro-
phenols found in a wide variety of environmental samples. This method
is rapid and sensitive and provides excellent simultaneous resolution of
chlorophenol isomers. The cost of the basic instrument is probably com-
petitive with ultraviolet and infrared instruments but is much less expen-
sive than the mass spectrometer. The aminoantipyrine colorimetric method,
although simple and rapid, lacks specificity; thus, it is only useful for
gross determination of chlorophenols. Thin-layer chromatography, infrared
and ultraviolet spectrophotometry, and mass spectrometry provide specific
identification but require large concentrations for detection.
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83
SECTION B.2
REFERENCES
1. Alexander, M., and M.I.H. Aleem. 1961. Effect of Chemical Struc-
ture on Microbial Decomposition of Aromatic Herbicides. J. Agric.
Food Chem. 9(1):44-47.
2. Aly, 0. M. 1968. Separation of Phenols in Waters by Thin Layer
Chromatography. Water Res. 2:587-595.
3. Aly, 0. M., and S. D. Faust. 1964. Studies on the Fate of 2,4-D
and Ester Derivatives in Natural Surface Waters. J. Agric. Food
Chem. 12(6):541-546.
4. Baird, R. B., C. L. Kuo, J. S. Shapiro, and W. A. Yanko. 1974. The
Fate of Phenolics in Wastewater — Determination by Direct-Injection
GLC and Warburg Respirometry. Arch. Environ. Contam. Toxicol.
2(2):165-178.
5. Baker, R. A. 1965. Microchemical Contaminants by Freeze Concentra-
tion and Gas Chromatography. J. Water Pollut. Control Fed. 37:1164-
1170.
6. Baker, R. A. 1966. Phenolic Analyses by Direct Aqueous Injection
Gas Chromatography. J. Am. Water Works Assoc. 58(6):751-760.
7. Barry, J. A., R. C. Vasishth, and F. J. Shelton. 1962. Analysis of
Chlorophenols by Gas-Liquid Chromatography. Anal. Chem. 34(1):67-69.
8. Bjerke, E. L., J. L. Herman, P. W. Miller, and J. H. Wetters. 1972.
Residue Study of Phenoxy Herbicides in Milk and Cream. J. Agric.
Food Chem. 20(5):963-967.
9. Bollag, J. M., C. S. Helling, and M. Alexander. 1968. 2,4-D Metab-
olism: Enzymatic Hydroxylation of Chlorinated Phenols. J. Agric.
Food Chem. 16(5):826-828.
10. Burttschell, R. H., A. A. Rosen, F. M. Middleton, and M. B. Ettinger.
1959. Chlorine Derivatives of Phenol Causing Taste and Odor. J.
Am. Water Works Assoc. 51:205-214.
11. Chesters, G., H. B. Pionke, and T. C. Daniel. 1974. Extraction and
Analytical Techniques for Pesticides in Soil, Sediment, and Water.
In: Pesticides in Soil and Water, W. D. Guenzi, ed. Soil Science
Society of America, Madison, Wis. pp. 451-550.
12. Clark, D. E., J. S. Palmer, R. D. Radeleff, H. R. Crookshank, and
F. M. Farr. 1975. Residues of Chlorophenoxy Acid Herbicides and
Their Phenolic Metabolites in Tissues of Sheep and Cattle. J. Agric.
Food Chem. 23(3):573-578.
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84
13. Cook, L. E., and R. C. Spangelo. 1974. Separation of Monosubsti-
tuted Phenol Isomers Using Liquid Crystals. Anal. Chem. 46(1):122-
126.
14. Cserjesi, A. J. 1972. Detoxification of Chlorinated Phenols. Int.
Biodeterior. Bull. 8(4):135-138.
15. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons, Inter-
science Publishers, New York. pp. 325-338.
16. Dow Chemical Company. 1977. Personal communication. Midland, Mich.
17. Dow Chemical Company. Undated. Organic Chemicals from Dow — Chlori-
nated Aromatics. Midland, Mich. 11 pp.
18. Eichelberger, J. W., R. C. Dressman, and J. E. Longbottom. 1970.
Separation of Phenolic Compounds from Carbon Chloroform Extract for
Individual Chromatographic Identification and Measurement. Environ.
Sci. Technol. 4(7):576-578.
19. Ettinger, M. B., and C. C. Ruchhoft. 1950. Persistence of Mono-
chlorophenols in Polluted River Water and Sewage Dilutions. U.S.
Public Health Service, Environmental Health Center, Cincinnati,
Ohio. 11 pp.
20. Ettinger, M. B., C. C. Ruchhoft, and R. J. Lishka. 1951. Sensitive
4-Aminoantipyrine Method for Phenolic Compounds. Anal. Chem. 23(12):
1783-1788.
21. Evans, W. C. , B.S.W. Smith, H. N. Fernley, and J. I. Davies. 1971.
Bacterial Metabolism of 2,4-Dichlorophenoxyacetate. Biochem. J.
122(4):543r551.
22. Faust, S. D., and 0. M. Aly. 1962. Determination of 2,4-Dichloro-
phenol in Water. J. Am. Water Works Assoc. 54(2)-.235-242.
23. Frei-Hausler, M. , R. W. Frei, and 0. Hutzinger. 1973. An Investi-
gation of Fluorigenic Labelling of Chlorophenols with Dansyl Chloride.
J. Chromatogr. 84(1):214-217.
24. Fritz, J. S., and R. B. Willis. 1973. Chromatographic Separation
of Phenols Using an Acrylic Resin. J. Chromatogr. 79:107-119.
25. Karapally, J. C. , J. G. Saha, and Y. W. Lee. 1973. Metabolism of
Lindane-^C in Rabbit: Ether-Soluble Urinary Metabolites. J. Agric.
Food Chem. 21(5):811-818.
26. Kawahara, F. K. 1971. Gas Chromatographic Analysis of Mercaptans,
Phenols, and Organic Acids in Surface Waters with Use of Pentaflu-
orobenzyl Derivatives. Environ. Sci. Technol. 5(3):235-239.
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85
27. Kurihara, N., and M. Nakajima. 1974. Studies on BHC Isomers and
Related Compounds: VIII. Urinary Metabolites Produced from y- and
3-BHC in the Mouse: Chlorophenol Conjugates. Pestic. Biochem.
Physiol. 4:220-231.
28. Loos, M. A., R. N. Roberts, and M. Alexander. 1967. Formation of
2,4-Dichlorophenol and 2,4-Dichloroanisole from 2,4-Dichlorophenoxy-
acetate by Arthrobacter sp. Can. J. Microbiol. 13(6):691-699.
29. Nachtigall, M. H., and R. G. Butler. 1974. Metabolism of Phenols
and Chlorophenols by Activated Sludge Microorganisms (abstract).
Abstr. Annu. Meet. Am. Soc. Microbiol. 1974:184.
30. Nakagawa, M., and D. G. Crosby. 1974. Photodecomposition of Nitro-
fen. J. Agric. Food Chem. 22(5):849-853.
31. Rand, M. C. , A. E. Greenberg, and M. J. Taras, eds. 1976. Phenols.
In: Standard Methods for the Examination of Water and Wastewater,
14th ed. American Public Health Association, American Water Works
Association, and Water Pollution Control Federation, Washington, B.C.
pp. 574-592.
32. Safe, S., W. D. Jamieson, and 0. Hutzinger. 1974. Ion Kinetic
Energy Spectroscopy: A New Mass Spectrometric Method for the Unam-
biguous Identification of Isomeric Chlorophenols. In: Mass Spec-
trometry and NMR Spectroscopy in Pesticide Chemistry. Plenum Press,
New York. pp. 61-70.
33. Shafik, T. M., H. C. Sullivan, and H. R. Enos. 1973. Multiresidue
Procedure for Halo- and Nitrophenols: Measurement of Exposure to
Biodegradable Pesticides Yielding These Compounds as Metabolites.
J. Agric. Food Chem. 21(2):295-298.
34. Sherman, M., J. Beck, and R. B. Herrick. 1972. Chronic Toxicity
and Residues from Feeding Nemacide [0-(2,4-Dichlorophenol)0,0-
Diethyl Phosphorothioate] to Laying Hens. J. Agric. Food Chem.
20(3):617-624.
35. Sidwell, A. E. 1971. Biological Treatment of Chlorophenolic Wastes:
The Demonstration of a Facility for the Biological Treatment of a
Complex Chlorophenolic Waste. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C.
177 pp.
36. Spokes, J. R., and N. Walker. 1974. Chlorophenol and Chlorobenzoic
Acid Co-metabolism by Different Genera of Soil Bacteria. Arch.
Microbiol. 96:125-134.
37. Steen, R. C., I. R. Schultz, D. C. Zimmerman, and J. R. Fleeker.
1974. Absence of 3-(2,4-Dichlorophenoxy)propionic Acid in Plants
Treated with 2,4-Dichlorophenoxyacetic Acid. Weed Res. 14(l):23-28.
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86
38. Walker, N. 1954. Preliminary Observations on the Decomposition of
Chlorophenols in Soil. Plant Soil 5(2):194-204.
39. Weber, J. B. 1972. Interaction of Organic Pesticides with Particu-
late Matter in Aquatic and Soil Systems. Adv. Chem. Ser. 111:55-120.
40. Zigler, M. G., and W. F. Phillips. 1967. Thin-Layer Chromatographic
Method for Estimation of Chlorophenols. Environ. Sci. Technol.
l(l):65-67.
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B.3 BIOLOGICAL ASPECTS IN MICROORGANISMS
B.3.1 BACTERIA
B.3.1.1 Metabolism
2-Chlorophenol and 2,4-dichlorophenol are amenable to metabolism by
bacteria found in soil and aquatic environments. The processes and path-
ways involved in metabolism are discussed fully in Section B.7; therefore,
only a brief overview is presented in this section.
Spokes and Walker (1974) used phenol-adapted bacterial cultures iso-
lated from soils to demonstrate the cometabolism of 2-chlorophenol by
Pseudomonas sp., Nocardia sp., Bacillus sp., and Mycobacterium coeliacum.
2-Chlorophenol was oxidized to 3-chlorocatechol. Further breakdown of
3-chlorocatechol through ring cleavage is evident (Evans et al., 1971).
Soil bacteria, namely Arthrobacter sp. and Pseudomonas sp., capable
of growing on and degrading 2,4-dichlorophenoxyacetic acid (2,4-D) can
also metabolize 2-chlorophenol and 2,4-dichlorophenol (Loos, Bollag, and
Alexander, 1967; Loos, Roberts, and Alexander, 1967; Bollag, Helling, and
Alexander, 1968; Evans et al., 1971). The metabolism of chlorophenols by
cells grown on 2,4-D, as indicated by loss of ultraviolet absorbancy and
chloride release after 3 hr of incubation, is shown in Table B.3.1. Dis-
appearance of ultraviolet absorption indicates cleavage of the aromatic
ring. In studies on the fate of 2,4-dichlorophenol, Bollag et al. (1968)
and Bollag, Helling, and Alexander (1968) obtained strong evidence for
the transformation of the compound to 3,5-dichlorocatechol by Arthrobacter
sp. Subsequent metabolism of the catechol resulted in cleavage of the
aromatic ring to form muconic acid, which may have been converted to di-
carboxylic acids, acetate, and chloride.
Aquatic bacteria, principally those present in activated sludge, have
shown an ability to degrade chlorophenols (Hemmett, 1972; Nachtigall and
Butler, 1974). This degradation is extremely important for the biological
treatment of wastes generated from the manufacture of chlorophenols and
2,4-D. Nachtigall and Butler (1974) isolated organisms from activated
sludge enriched with various phenolic compounds, including 2-chlorophenol
and 2,4-dichlorophenol. Organisms identified were Pseudomonas sp. and
Noeardia sp. Warburg respirometric studies indicated that Pseudomonas
sp. oxidized all phenols and chlorophenols, but flocardia sp. oxidized
phenol and the monochlorophenols. Pseudomonas sp. isolated and grown on
2-phenylphenol oxidized the compound and cooxidized monochlorophenols
and dichlorophenols. Several species of bacteria are apparently capable
of using chlorophenols as their sole carbon source or are capable of uti-
lizing the chemicals after being adapted to closely related compounds.
B.3.1.2 Effects
The bactericidal properties of chlorophenols have been known for
many years (Klarmann, 1963; Sykes, 1965; Baker, Schumacher, and Roman,
87
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88
TABLE B.3.1. METABOLISM OF CHLOROPHENOLS BY AN ARTHROBACTER
SPECIES GROWN ON 2,4-D OR CITRATE
Activity by cells grown on
2,4-D Citrate
auDStraLt;
Loss of uv
absorbancy
2,4-D + + +
4-Chlorophenoxyacetic acid + +
2-Chlorophenoxyacetic acid + +
6-Hydroxy-2 , 4-dichlorophenoxyacetic acid
2-Hydroxy-4-chlorophenoxyacetic acid +
2,4-Dichlorophenol + + +
4-Chlorophenol + + +
2-Chlorophenol + + +
4-Chlorocatechol + + +
3,5-Dichlorocatechol + + +
Catechol + + +
Chloride
release^
96
60
20
0
2
96
98
97
81
107e
, Chloride
Loss of uv -, h
, , a release0
absorbancy ,„.
0
0
0
(+) 14
+ 10
+ 5
(+) 73
+ 0
+ +
+ + +, complete disappearance of the substrate absorption spectrum; + +, considerable
decrease in the intensity of absorption without a change in the shape of the spectrum; +,
slight decrease in the intensity of absorption without a change in the shape of the spectrum;
(+), change in the shape of the spectrum to yield a poorly defined spectrum, with or without a
change in the intensity of absorption; -, no change in the shape of the spectrum or in the
intensity of absorption.
^Percentage of the total chlorine released as chloride by the end of the incubation
period.
"^When the experiment was repeated with a different batch of cells, the value was 48.
Source: Adapted from Loos, Roberts, and Alexander, 1967, Table I, p. 683. Reproduced by
permission of the National Research Council of Canada from the Canadian Journal of Microbiol-
ogy, Volume 13, pp. 679-690, 1967.
1970). Potentiation of antibacterial effectiveness generally increases
with degree of chlorine substitution up to the trichloro derivatives
(Table A.3.2). The tetrachloro isomers are considerably less active than
any of the trichloro isomers, and pentachlorophenol is about as effective
as the phenol itself. However, some of the higher chlorophenols have en-
hanced fungicidal activity, particularly pentachlorophenol.
Bactericidal action of disinfectants is usually expressed in terms
of the phenol coefficient. The phenol coefficient measures, under iden-
tical conditions, the highest dilution of test disinfectants effective
to kill in 10 min relative to phenol. Thus, disinfectants with high phe-
nol coefficients are more potent. Table A.3.2 compares the antibacterial
action of 2-chlorophenol and 2,4-dichlorophenol with other chlorophenols
and alkyl chlorophenols on Salmonella fyphosa and Staphyloooceus aureus.
Klarmann, Shternov, and Gates (1933) found variation in species suscepti-
bility to 2-chlorophenol. The phenol coefficients for Salmonella typhosa,
Salmonella schottmuelleri,, Staphylococcus aureas, a homolytic strain of
Streptococcus, Myaobacterium smegmatts, and Triohophyton rosaceum were
2.5, 2.3, 2.9, 2.0, 2.2, and <1.0 respectively.
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89
The effect of 2,4-dichlorophenol on the growth rate of Pseudomonas
sp., a bacterial species that abounds in soils, was studied in batch and
continuous culture (Tyler and Finn, 1974). The growth rate of the orga-
nism was strongly inhibited by 2,4-dichlorophenol at concentrations above
25 mg/liter. Growth followed Monod kinetics at subinhibitory concentra-
tions, above which the growth rate decreased linearly with concentration
and did not fit a model based on noncompetitive inhibition. The lag phase
of batch cultures was found to depend on 2,4-dichlorophenol concentration
and prior adaptation of the inoculum.
The mode of antibacterial action of phenolic compunds may involve
several steps beginning with adsorption on the bacterial cells, going
through the inactivation of certain essential enzymes, and terminating
with lysis and death of cells (Klarmann, 1963). The degree of cell in-
activation depends largely on concentration. At higher concentrations,
the chemicals act as a gross protoplasmic poison, rapidly penetrating and
rupturing the cell walls; low concentrations permit the leakage of cell
constituents and inactivation of specific enzyme systems. Some studies
on the mechanism of action of chlorophenols have indicated that cell mem-
brane damage is a primary effect (Judis, 1962, 1963, 1965a). Judis (19652?)
investigated the effect of 2,4-dichlorophenol on the incorporation of lilC-
labeled substrates by Esoheviohia coli. When E. ooli was exposed to a
concentration (66.5 ug/ml) sufficient to inhibit growth in a synthetic
medium, the organism was able to incorporate substantial amounts of radio-
activity from several amino acids but negligible amounts from thymine,
acetate, and succinate. Incorporation was completely inhibited by doubling
the concentration to 133 yg/ml. Results suggest that at concentrations
sufficient to prevent growth, 2,4-dichlorophenol does not inhibit synthe-
sis of protein and ribonucleic acid but deactivates succinic dehydrogenase.
Succinic dehydrogenase is known to be located in the cell membrane; there-
fore, any damage to the cell wall by the bactericide is detrimental to the
activity of the enzyme. In addition, bacterial lipids are found mostly
in the cell wall so that lipophilic compounds tend to associate with lipids
and alter cell permeability (Baker, Schumacher, and Roman, 1970).
B.3.2 FUNGI
B.3.2.1 Metabolism
Few investigations of the metabolism of monochlorophenols and dichlo-
rophenols by fungi were found; these are discussed in Section B.7. Walker
(1973) demonstrated the cometabolism of 2-chlorophenol and 2,4-dichloro-
phenol by phenol-grown cells of the yeast Rhodotorula glutinis. Involve-
ment of the induced enzyme system was manifested by the inability of the
organism to utilize chlorophenols as a sole carbon source. Results indi-
cate that the phenomenon of cometabolism of aromatic halogen compounds is
not restricted to bacteria. Oxidases (laccase, tyrosinase, and peroxidase)
found in white rot fungi are thought to be responsible for the degradation
of phenols in wood materials. In a study of the detoxification of chloro-
phenols, including 2,4-dichlorophenol, Lyr (1962) concluded that these
enzymes are involved in the degradation of the chlorophenols by decay fungi.
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90
The nature of degradation products resulting from fungal metabolism has
not been identified.
B.3.2.2 Effects
Chlorophenols possess fungicidal properties. The antifungal activity
of 2-chlorophenol has been evaluated by testing it against Aspergillus
niger, one of the more resistant species of fungi (Mason, Brown, and Minga,
1951; Shirk and Corey, 1952). Table B.3.2 shows the inhibiting concen-
tration of phenolic compounds, including 2-chlorophenol, in sterilized
broth solution inoculated with A. niger at 37°C. Although 2-chlorophenol
is more effective than phenol, its potency is less than that of either 3-
or 4-chlorophenol and several substituted phenolic compounds. Shirk and
Corey (1952) reported that a 0.0014 M concentration of 2-chlorophenol in-
hibited growth of A. niger by 50% as compared with a 0.0045 M concentration
of phenol.
TABLE B.3.2.
INHIBITORY EFFECT OF PHENOLIC COMPOUNDS
ON ASPERGILLVS NIGER
Compound
Inhibiting
concentration
3-Chlorophenol
4-Chlorophenol
2-Chlorophenol
Phenol
2-Chloro-4-nitrophenol
4-Nitrophenol, sodium salt
4-PhenyIpheno1
2-Chloro-4-phenylphenol, sodium salt (Dowicide D)
Mixture of 2- and 4-chloro-6-phenylphenol, sodium
salt (Dowicide 31)
2-Bromo-4-phenylphenol, sodium salt (Dowicide 5)
2,2'-Methylenebis(4-chlorophenol)
2,4,5-Trichlorophenol, sodium salt (Dowicide B)
Pentachlorophenol, sodium salt (Dowicide G)
2,3,4,6-Tetrachlorophenol, sodium salt (Dowicide F)
0.015
0.015
0.030
0.060
0.0075
0.025
0.0038
0.0075
0.0075
0.031
0.0063
0.0075
0.015
0.031
Source: Adapted from Mason, Brown, and Minga, 1951, Table 2,
p. 167. Reprinted by permission of the publisher.
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91
B.3.3 ALGAE
B.3.3.1 Metabolism
No data on algal metabolism of monochlorophenols and dichlorophenols
are available.
B.3.3.2 Effects
Algae are important in waste stabilization ponds for reoxygenation
purposes. Therefore, there is considerable concern about the toxic effects
of organic chemicals, including chlorophenols, on the photosynthetic activ-
ity of algae. Huang and Gloyna (1967) investigated the effects of chloro-
phenols and other organic chemicals on the synthesis of chlorophyll by
the blue-green alga ChZoret'la pyrenoidosa under laboratory conditions.
Chloyella was selected as the test organism because it is commonly found
in streams and waste stabilization ponds; also, it is most frequently
used in physiological and biochemical studies. Table A.3.4 indicates the
chlorophyll content of algae treated with different levels of chlorophenols,
and Table A.3.5 lists the toxicity constants. As seen in Table A.3.4,
concentrations of 2-chlorophenol above 10 mg/liter progressively decreased
the chlorophyll content of the algae. At 500 mg/liter, chlorophyll syn-
thesis was completely inhibited. Smaller amounts of 2,4-dichlorophenol
were needed to impair the photosynthesis of the algal cells; at 100
mg/liter the cells ceased to function. Evidently, 2,4-dichlorophenol is
almost five times as toxic as 2-chlorophenol. From toxicity data, it was
concluded that increasing the number of chlorine atoms on the aromatic
ring of chlorophenols enhanced their toxicity. The same relationships
have been reported with regard to the bactericidal properties of these
chemicals.
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92
SECTION B.3
REFERENCES
1. Baker, J. W., I. Schumacher, and D. P. Roman. 1970. Antiseptics
and Disinfectants. In: Medicinal Chemistry, Part I, 4th ed.,
A. Burger, ed. John Wiley and Sons, Interscience Publishers, New
York. pp. 627-661.
2. Bollag, J. M., G. G. Briggs, J. E. Dawson, and M. Alexander. 1968.
2,4-D Metabolism: Enzymatic Degradation of Chlorocatechols. J.
Agric. Food Chem. 16(5):829-833.
3. Bollag, J. M., C. S. Helling, and M. Alexander. 1968. 2,4-D Meta-
bolism: Enzymatic Hydroxylation of Chlorinated Phenols. J. Agric.
Food Chem. 16(5):826-828.
4. Evans, W. C., B.S.W. Smith, H. N. Fernley, and J. I. Davies. 1971.
Bacterial Metabolism of 2,4-Dichlorophenoxyacetate. Biochem. J.
122(4):543-551.
5. Hemmett, R. B., Jr. 1972. The Biodegradation Kinetics of Selected
Phenoxyacetic Acid Herbicides and Phenols by Aquatic Microorganisms
(abstract). Diss. Abstr. Int. B 32(12):7097.
6. Huang, J. C., and E. F. Gloyna. 1967- Effects of Toxic Organics
on Photosynthetic Reoxygenation. University of Texas, Center for
Research in Water Resources, Austin. 163 pp.
7. Judis, J. 1962. Studies on the Mechanism of Action of Phenolic
Disinfectants: I. Release of Radioactivity from Carbon1^-labeled
Esoherichia ooli. J. Pharm. Sci. 51(3):261-265.
8. Judis, J. 1963. Studies on the Mechanism of Action of Phenolic
Disinfectants: II. Patterns of Release of Radioactivity from
Escherichia ooli Labeled by Growth on Various Compounds. J. Pharm.
Sci. 52(2):126-131.
9. Judis, J. 1965a. Mechanism of Action of Phenolic Disinfectants:
IV. Effects on Induction of and Accessibility of Substrate to
B-Galactosidase ±n Esaherichia coli. J. Pharm. Sci. 54(3):417-420.
10. Judis, J. 1965Z?. Mechanism of Action of Phenolic Disinfectants:
V. Effect of 2,4-Dichlorophenol on the Incorporation of Labeled
Substrates by Escherichia soli. J. Pharm. Sci. 54(4)-.541-544.
11. Klarmann, E. G. 1963. Antiseptics and Disinfectants. In: Kirk-
Othmer Encyclopedia of Chemical Technology, 2nd ed., Vol. 2. John
Wiley and Sons, Interscience Publishers, New York. pp. 623-630.
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93
12. Klarmann, E. , V. A. Shternov, and L. W. Gates. 1933. The Alkyl
Derivatives of Halogen Phenols and Their Bactericidal Action: I.
Chlorophenols. J. Am. Chem. Soc. 55:2576-2589.
13. Loos, M. A., J. M. Bollag, and M. Alexander. 1967. Phenoxyacetate
Herbicide Detoxication of Bacterial Enzymes. J. Agric. Food Chem.
15(5):858-860.
14. Loos, M. A., R. N. Roberts, and M. Alexander. 1967. Phenols as
Intermediates in the Decomposition of Phenoxyacetates by an Arthro-
bacter species. Can. J. Microbiol. 13(6):679-690.
15. Lyr, H. 1962. Detoxification of Heartwood Toxins and Chlorophenols
by Higher Fungi. Nature (London) 195:289-290.
16. Mason, C. T., R. W. Brown, and A. E. Minga. 1951. The Relation-
ship between Fungicidal Activity and Chemical Constitution. Phyto-
pathology 41:164-171.
17. Nachtigall, M. H. , and R. G. Butler. 1974. Metabolism of Phenols
and Chlorophenols by Activated Sludge Microorganisms (abstract).
Abstr. Annu. Meet. Am. Soc. Microbiol. 1974:184.
18. Shirk, H. G. , and R. R. Corey, Jr. 1952. The Influence of Chemical
Structure on Fungal Activity: III. Effect of o-Chlorination on
Phenols. J. Am. Water Works Assoc. 44:417-423.
19. Spokes, J. R. , and N. Walker. 1974. Chlorophenol and Chlorobenzoic
Acid Co-metabolism by Different Genera of Soil Bacteria. Arch.
Microbiol. 96:125-134.
20. Sykes, G. 1965. Phenols, Soaps, Alcohols and Related Compounds.
In: Disinfection and Sterilization, 2nd ed. E. and F. N. Spon
Ltd., London, pp. 311-349.
21. Tyler, J. E. , and R. K. Finn. 1974. Growth Rates of a Pseudomonad
on 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol. Appl.
Microbiol. 28(2):181-184.
22. Walker, N. 1973. Metabolism of Chlorophenols by Rhodotorula
glutinis. Soil Biol. Biochem. 5:525-530.
-------
B.4 BIOLOGICAL ASPECTS IN PLANTS
B.4.1 METABOLISM
B.4.1.1 Uptake and Absorption
No information on the uptake of 2-chlorophenol in vascular plants
was found. Based upon its chemical similarity to 2,4-dichlorophenol,
residues of 2-chlorophenol may occur in plants following metabolism of
2,4-dichlorophenol.
2,4-Dichlorophenol may be absorbed by vascular plants through the
roots or foliage, or it may be produced in vascular plants as a result of
detoxification of the commonly used herbicide 2,4-dichlorophenoxyacetic
acid (2,4-D). The formation of 2,4-dichlorophenol from 2,4-D has been
demonstrated in sunflowers, corn, barley, strawberries, kidney beans,
and other vascular plants (Luckwill and Lloyd-Jones, 1960; Doedens, 1963;
Steen et al., 1974). The transport and distribution of 2,4-dichlorophenol
formed during 2,4-D degradation is expected to be similar to that of 2,4-
dichlorophenol absorbed by root or foliar uptake.
Uptake of 2,4-dichlorophenol from nutrient solutions and soils or up-
take following foliar application was studied by Isensee and Jones (1971).
Oat (Avena sativa L. 'Markton') and soybean (Glycin& max L. 'Lee') tissues
grown in nutrient solution containing ll>C-labeled 2,4-dichlorophenol were
analyzed from 1 to 14 days following introduction of 2,4-dichlorophenol
into the medium. 2,4-Dichlorophenol levels in the roots and shoots of
treated soybeans and oats are shown in Table B.4.1. 2,4-Dichlorophenol
reached a stable concentration in the roots within 24 hr and remained con-
stant or declined for the remainder of the experiment. Furthermore, as
much as 85% of the 2,4-dichlorophenol present in the nutrient solution
was sorbed by the roots of soybeans and up to 71% was sorbed by oats.
These data are difficult to interpret because the degree to which absorp-
tion or adsorption contributes to the total root content is unknown. How-
ever, substantial amounts of 2,4-dichlorophenol are clearly sorbed by the
roots of oats and soybeans within 24 hr.
Absorption of 2,4-dichlorophenol from treated soil was also studied
by Isensee and Jones (1971). In a greenhouse experiment, oats and soy-
beans were planted in pots of Lakeland sandy loam treated with ^C-labeled
2,4-dichlorophenol and watered when needed. The shoots of the soybean and
oat plants were harvested on the 6th, 10th, 20th, 25th, 30th, and 40th days
after planting. Soybean and oat plants were also harvested on the 50th
and 85th day, respectively, and the plant tissues were analyzed for 2,4-
dichlorophenol (Table B.4.2). The 2,4-dichlorophenol content (microgram
per gram) decreased as the age of the soybean and oat plants increased.
In general, the total content of 2,4-dichlorophenol (expressed as a per-
centage of the total radioactivity of the soils) increased for the first
15 to 20 days and remained relatively constant thereafter. Tissue dilu-
tion, metabolism, volatilization from the tissue, or translocation back
to the roots could account for a relationship of this type; however, it
94
-------
95
TABLE B.4.1. UPTAKE OF lilC-LABELED 2,4-DICHLOROPHENOL
BY TEN-DAY-OLD OAT AND SOYBEAN PLANTS FROM NUTRIENT
SOLUTIONS CONTAINING 0.18 TO 0.26 ing/liter
2,4-DICHLOROPHENOL
Time in
nutrient
solution
(days)
1
2
4
6
8
10
12
14
Control
2,4-Dichlorophenol content01
Roots
(yg/g dry
tissue)
273 u
239 uv
178 vw
115 vw
132 w
128 w
107 w
87 w
0.060
(%)*
Soybeans
83.6 u
83.4 u
83.3 M
75.0 v
79.3 «y
84.7 u
83.8 M
75.0 y
Shoots
(yg/g dry
tissue)
0*1 n
.33 yy
0.40 wy
0.49 u
0.36 uy
0.19 wx
0.11 a;
0.10 a:
0.13 x
0.002
«)s
0.29 w
0.40 yw
0.64 u
0.50 uv
0.33 yw
0.32 w
0.30 w
0.32 w
Oats
1
2
4
6
8
10
12
14
Control
87
100
99
106
101
98
87
90
0.
u
uv
uv
V
uv
uv
u
u
070
56.
61.
59.
66.
72.
71.
65.
68.
0
8
8
5
5
2
4
5
u
vw
uv
wxy
z
y*
wx
xyz
2
2
2
1
1
1
1
1
0
.05
.40
.74
.88
.89
.91
.73
.85
.010
u
w
u
w
u
u
u
u
0
0
0
0
1
1
1
1
.46
.69
.86
.73
.07
.03
.02
.37
u
uv
uvw
uv
vw
vw
vw
w
"^Numbers followed by the same letter are not signif-
icantly different at the 5% level of probability.
^Tissue content expressed as percentage of total
activity available to plants.
^Plants grown in nutrient solution devoid of 2,4-
dichlorophenol and harvested at 14 days.
Source: Adapted from Isensee and Jones, 1971, Table
I, p. 1211. Reprinted by permission of the publisher.
-------
96
TABLE B.4.2. UPTAKE OF 1AC-LABELED 2,4-DICHLOROPHENOL
BY OATS AND SOYBEANS FROM SOIL CONTAINING 0.07 mg/kg
OF 2,4-DICHLOROPHENOL
Time in
nutrient
solution
(days)
2,4-Dichlorophenol content
Oats
Soybeans
(yg/g dry
tissue)
(Ug/g dry
tissue)
Treated soil
6
10
15
20
25
30
40
50 (tissue)
50 (seeds)
85 (tissue)
85 (seeds)
0.195 u
0.173 u
0.115 v
0.093 vw
0.073 wx
0.055 xy
0.038 y
0.010
<0.001
0.049
0.130 v
0.149 v
0.197 u
0.164 uv
0.154 v
0.160 uv
0.062 w
1.480 u
0.085 v
0.093 V
0.083 v
0.048 v
0.040 y
0.028 t;
0.023 -o
0.011
0.889 u
0.055 x
0.127 w
0.187
0.192
0.215
0.170 vw
0.174 vw
0.003
vw
V
V
Untreated soil
10
20
30
50 (tissue)
50 (seeds)
85 (tissue)
85 (seeds)
0.032
0.010
0.005
<0.001
<0.001
0
0
0
0
.028
.006
.002
.003
lumbers followed by the same letter are not signifi-
cantly different at the 5% level of probability.
^Tissue content expressed as percentage of total activ-
ity available in treated soil.
Source: Adapted from Isensee and Jones, 1971, Table II,
p. 1212. Reprinted by permission of the publisher.
-------
97
was impossible to determine which, if any, of these processes were operat-
ing. Smaller quantities of 2,4-dichlorophenol were taken up from soil
(Table B.4.2) than from solution (Table B.4.1). Plants harvested follow-
ing 10, 15, 20, and 25 days of uptake of 2,4-dichlorophenol from soil cor-
responded roughly in age to plants harvested at 1, 4, 10, and 14 days in
the nutrient solution experiment. When these values were compared on an
equal-age basis, oats took up 8 to 25 times more 2,4-dichlorophenol from
solution than from soil. The difference in the amounts taken up by soy-
beans from the two media was smaller (i.e., one to five times). Differ-
ences in uptake from soil and solution decreased with increased plant age.
Thus, rates of 2,4-dichlorophenol uptake by the roots of vascular plants
depend on factors such as species differences, age, and composition and
type of growth media. Absorption of 2,4-dichlorophenol following foliar
application was demonstrated by Isensee and Jones (1971) , but the data
provide little insight into uptake rates because the detergent Tween-80
was included in the 2,4-dichlorophenol formulation to enhance absorption.
B.4.1.2 Transport and Distribution
No information was found on the distribution and transport of
2-chlorophenol in vascular plants and very little was found on 2,4-dichlo-
rophenol. The data in Tables B.4.1 and B.4.2 indicate that 2,4-dichloro-
phenol is transported to the shoots of vascular plants following root
absorption (Isensee and Jones, 1971). However, only small quantities of
2,4-dichlorophenol absorbed by the roots were translocated to the shoots
of soybean and oat plants (Table B.4.1.). Some differences in the trans-
location patterns of 2,4-dichlorophenol in soybeans and in oats are evi-
dent. 2,4-Dichlorophenol accumulated in soybean shoots for several days,
declined slightly, and reached a stable concentration over the 14-day per-
iod of the experiment. On the other hand, 2,4-dichlorophenol levels in
oat shoots reached a stable level within 24 hr which was maintained over
the 14 days. A different pattern emerges when oats and soybeans absorb
2,4-dichlorophenol from treated soil (Table B.4.2). During the process
of absorption from soil, the tissue concentration of 2,4-dichlorophenol
(microgram per gram) decreased as the plants aged. However, total content
of 2,4-dichlorophenol expressed as a percentage of the initial dose in-
creased for 15 to 20 days and then remained relatively constant for the
duration of the experiment. The authors suggested that tissue dilution
resulting from plant growth may account for these relationships. Other
possible explanations for this pattern are changes due to metabolism in
the tissue, volatilization of 2,4-dichlorophenol from the tissue, or
translocation back to the roots. Based on the data presented, it is im-
possible to establish which, if any, of these processes are operating in
oats or soybeans. When the oats were fully ripened, no evidence was found
of 2,4-dichlorophenol translocation to the grain. Small quantities (1%
to 2% of total tissue content) of 2,4-dichlorophenol were found in soybean
seeds; however, it was concluded that oats and soybeans are unable to
concentrate the compound in their seeds.
In general, oats and soybeans absorbed and translocated small but
substantial amounts of 2,4-dichlorophenol when they were grown in either
nutrient solutions or soil containing 2,4-dichlorophenol (Isensee and
-------
98
Jones, 1971). Following 14 days of uptake from a nutrient solution con-
taining 0.20 mg/liter of 2,4-dichlorophenol, seedling oats and soybeans
contained 1.84 and 0.13 ug/g of the compound respectively (i.e., a con-
centration factor for oats of nine times the 2,4-dichlorophenol concen-
tration in the nutrient solution). Soybeans apparently do not concentrate
2,4-dichlorophenol from nutrient solution. After growing to maturity on
soil containing 0.07 mg/kg 2,4-dichlorophenol, oats and soybeans contained
0.01 and 0.02 yg/g 2,4-dichlorophenol respectively; thus, little or no
concentration of 2,4-dichlorophenol from soil was noted.
These investigations by Isensee and Jones (1971) indicate that 2,4-
dichlorophenol applied to leaves is not translocated in soybeans. Soybean
plants were harvested 2, 7, 14, and 21 days following foliar application
of 2,4-dichlorophenol to the center leaflet of the first trifoliate leaf.
The plants were dissected into six parts: treated leaflet, remainder of
the first trifoliate leaf plus petiole, second trifoliate, all remaining
trifoliate leaves, first true leaves, and stem. These samples were ana-
lyzed individually for 2,4-dichlorophenol; the data indicated that 2,4-
dichlorophenol was not translocated beyond the treated leaflet. Carbon-14
activity detected in the untreated portions of the plants was equal to or
less than the background activity for control plants. Because no visual
phytotoxicity was evident from the application of 2,4-dichlorophenol, it
was assumed that the capacity for translocation was not impaired. Forty-
eight hours after application, 2% of the applied 2,4-dichlorophenol re-
mained on the treated soybean leaf. Volatilization from the leaf surface
was believed to account for this loss; application of 2,4-dichlorophenol
to glass surfaces resulted in 96% volatilization in 48 hr.
B.4.1.3 Biotransformation
The metabolism of 2-chlorophenol in vascular plants is not well stud-
ied. The only report found demonstrated that 2-chlorophenol may be inac-
tivated by glycoside formation in plant tissue. When certain nonnaturally
occurring chemicals are absorbed by various plants, glycoside formation
takes place with the foreign chemical serving as the aglycon. Miller
(1941) found that the metabolic fate of 2-chlorophenol in tomato plants
included glycoside formation. Tomato plants of the Marglobe and Bonny Best
varieties were grown in sand cultures containing 2-chlorophenol. Tomato
plants (3 to 4 in. high) were planted in sand cultures, and 2-chlorophenol
was added when the plants were 13 to 14 in. high (approximately 33 days
after transfer to the sand culture). The 2-chlorophenol was added four
to six times per week, and each pot received 0.1 mA/ 2-chlorophenol at each
application point. A total of 2.8 wM 2-chlorophenol was added to each
culture in "5-inch pots." The pots probably had a capacity of about 3000
g soil to give a total addition of 100 to 120 mg chlorophenol per kilogram
soil. 8-o-Chlorophenyl gentiobioside (a glycoside of 2-chlorophenol) was
isolated from the roots of these tomato plants. There was no evidence
that the glycoside was formed in shoots. The fate of this metabolic prod-
uct of 2-chlorophenol in plants is not known and warrants further inves-
tigation. Glycoside formation likely involves the immobilization of the
toxic chemical, thereby preventing it from reaching the normal sites of
its toxic action.
-------
99
Information on the biotransformation of 2,4-dichlorophenol is also
scant. Considerable information does exist, however, on the production
of 2,4-dichlorophenol as a metabolic breakdown product of other compounds
in vascular plants. Some highlights of these studies are presented because
this information directly relates to possible sources of 2,4-dichlorophenol
in plants.
Investigations conducted .by Luckwill and Lloyd-Jones (1960) indicate
that 2,4-dichlorophenol may be detoxified in the strawberry by conjugation,
specifically by glycoside formation and immobilization of the compound.
Experiments showed that quantitative recovery of 2,4-dichlorophenol from
Tallisman strawberry leaves could only be achieved following hydrolysis
of the plant tissue with NaOH under reflux conditions. No information was
given on the enzymes or enzyme systems responsible for the conjugation,
the types of degradation products formed, or the rate of transformation.
Chkanikov et al. (1976) reported that the high resistance of strawberries
to 2,4-D is caused by destruction of the ether bond in the herbicide, lead-
ing to the formation of 2,4-dichlorophenol. Other means of detoxification
such as ring cleavage of 2,4-dichlorophenol are possible; however, no data
addressing this question are available.
Bristol et al. (1974) determined the persistence times of 2,4-D and
2,4-dichlorophenol in potato tubers. Analyses of potato tubers for 2,4-D
and 2,4-dichlorophenol showed a residue level of 2,4-dichlorophenol which
was greater than 10% of the 2,4-D residue level. Dissipation rates of
2,4-D and 2,4-dichlorophenol from whole, treated potatoes stored at 38°F
(3°C) were determined; 2,4-D residues decreased with a half-life of about
12 weeks, but residues of 2,4-dichlorophenol remained constant over this
period.
Sokolov et al. (1974) studied the metabolism, sorption, migration,
and persistence of 2,4-D in irrigated rice fields. Large quantities of
2,4-dichlorophenol were found in rice plants and in soil following herbi-
cidal application. Although 2,4-D residues were found in rice plants
during the first month of application, rice grains contained neither her-
bicide nor metabolite (2,4-dichlorophenol) residues when the plants
reached maturity.
B.4.1.4 Elimination
Investigations on the route or rate of 2-chlorophenol and 2,4-dichlo-
rophenol elimination from vascular plants were not found. Unfortunately,
the uptake studies conducted by Isensee and Jones (1971) do not allow cal-
culation of excretion rates or routes. 2,4-Dichlorophenol is likely dis-
sipated from vascular plants by one of three routes: volatilization from
leaf surfaces or stems, metabolism of the compound with subsequent excre-
tion of metabolic breakdown products, or excretion through the roots.
Isensee and Jones (1971) demonstrated that >98% of the 2,4-dichlorophenol
applied to the foliage of soybean plants was lost, probably due to vola-
tilization, within 72 hr of application. Information regarding metabolic
breakdown of 2,4-dichlorophenol and subsequent excretion of metabolic prod-
ucts is not available. Dexter, Slife, and Butler (1971) found that certain
-------
100
plants avoid injury following exposure to 2,4-D by excretion through their
root systems. Thus, a precedent exists for possible excretion by the roots
as a route of 2,4-dichlorophenol elimination from plants; however, no
studies addressed this point.
B.4.2 EFFECTS
2-Chlorophenol or 2,4-dichlorophenol would likely be applied to soil
or plants only if they were combined with or were contaminants of some
other material. Neither is used in any manner involving direct applica-
tion to plants. The herbicide 2,4-D may be contaminated with 2,4-dichlo-
rophenol, but no data are available on the extent of contamination. The
most likely source of these chlorophenols in plants is degradation of
plant-assimilated 2,4-D.
B.4.2.1 Physiological or Biochemical Role
There is no evidence that 2-chlorophenol or 2,4-dichlorophenol play
any necessary metabolic role in vascular plants; thus, their presence in
plant tissues probably results from environmental contamination.
B.4.2.2 Toxicity
B.4.2.2.1 Mechanism of Action — Very little information on the mech-
anisms of toxicity of 2-chlorophenol or 2,4-dichlorophenol to vascular
plants was found. Some notable effects of 2-chlorophenol and 2,4-dichlo-
rophenol on in vitro enzyme systems have been documented.
•
2-Chlorophenol produced reversible inhibition of etiolated pea brei
(a finely divided tissue suspension) catalase and of crystalline beef liver
catalase in vitro at a level of 4 x 10"5 M. The importance of the phenom-
enon is unknown (Goldacre and Galston, 1953).
A number of reports have documented an effect of 2,4-dichlorophenol on
in vitro enzyme systems. Indoleacetic acid is a phytohormone which is im-
portant in the growth regulation of plants. Indoleacetic acid oxidase is
an enzyme system which regulates endogenous indoleacetic acid levels and
presumably plays a role in growth regulation. It has been found that the
in vitro activity of indoleacetic acid oxidase enzyme preparations depends
on the presence of 2,4-dichlorophenol (or related phenols). This phenome-
non has been observed in indoleacetic acid oxidase systems derived from the
pea (Piston sativzffn) epicotyl (Taniguchi, Yamaguchi, and Satomura, 1973),
root extracts of Lens culinaris and Phaseolus vulga&is (Dinant, Caspar,
and Avella, 1967), and maize (Zea mays) root preparations (Psenakova et
al., 1971). The mechanism for this cofactor-type activity of 2,4-dichlo-
rophenol is not understood. Because 2,4-dichlorophenol has not been found
as a normal constituent of plant tissue, it must be assumed that by virtue
of its chemical structure it mimics compounds which normally act on the
indoleacetic acid oxidase system in plants. Goldacre and Galston (1953)
found that 2,4-dichlorophenol produced a reversible in vitro inhibition
of etiolated pea brei catalase and of crystalline beef liver catalase.
Other heme enzymes (e.g., peroxidase, cytochrome oxidase, and hemoglobin)
-------
101
were unaffected by 2,4-dichlorophenol at a concentration of 2 x 10"6 .'/.
The bactericidal properties of 2,4-dichlorophenol may be due in part to
this effect on the catalase system. Furthermore, the fact that 2,4-
dichlorophenol inhibits catalase without affecting peroxidase indicates
that 2,4-dichlorophenol may block catalase activity in reactions where
catalase may be expected to compete with peroxidase for available H202.
This phenomenon may partly account for the 2,4-dichlorophenol activation
of indoleacetic acid oxidase mentioned previously.
B.4.2.2.2 General Toxicity — No information exists on the phytotoxic
effects of 2-chlorophenol in vascular plants. Due to the chemical similar-
ity to 2,4-D, 2,4-dichlorophenol may display some of the same toxic effect-
in plants as the herbicide; however, data on the toxicity of 2,4-dichloro-
phenol to vascular plants are scant.
2,4-Dichlorophenol inhibited root growth in flax seedlings, cell
expansion in wheat coleoptiles, and the growth-stimulating effect of in-
doleacetic acid in wheat (Volynets and Pal'chenko, 1972). Luckvill and
Lloyd-Jones (1960) found that apples, strawberries, and currants appeared
to possess a detoxification mechanism for 2,4-dichlorophenol. Relatively
large quantities of 2,4-dichlorophenol were fed through the transpiration
stream of leaves of these plants, but no phytotoxic symptoms were observed.
These plant varieties are also resistant to the effects of 2,4-D. Because
2,4-D may be decarboxylated to yield 2,4-dichlorophenol in vascular plants,
the detoxification mechanism responsible for 2,4-dichlorophenol inactiva-
tion may be a portion of an overall 2,4-D metabolizing system. No infor-
mation was found on the toxicological properties of 2,4-dichlorophenol in
terrestrial vascular plants, but one report discussed the toxicological
effects of 2,4-dichlorophenol on the aquatic plant Lemna. ""I-'.-?. Blackman
et al. (1955<2 ) determined the 2,4-dichlorophenol concentration in water
causing the death of 50% of the Lerwia. -ci^r fronds following a 48-hr expo-
sure; the LCSO value was 40 mg/liter. Other investigations by Blackman
et al. (19552?) indicate that the physiological effect of chlorophenols is
increased as the pH of the medium approaches the pK of the chlorophenol.
The metabolism of chlorophenoxyacetic acids to chlorophenols occurs
in many plant species. A typical investigation demonstrating the produc-
tion of 2,4-dichlorophenol from 2,4-D was conducted by Steen et al. (1974).
2,4-Dichlorophenol levels in plant tissues after foliar and root applica-
tion of 2,4-D are given in Tables B.4.3 and B.4.4.
B.4.2.2.3 Mitotic Effects — No information regarding possible mi-
totic effects of 2-chlorophenol was found, but several studies reported
on the effect of 2,4-dichlorophenol on plant mitosis. Amer and Ali (1969)
studied the effect of 2,4-dichlorophenol on root mitosis of ~.''icia fzba.
At a concentration of 62.5 mg/liter 2,4-dichlorophenol, there was a de-
creased mitotic index and an increased frequency of induced mitotic anom-
alies, such as cytomixis, stickiness, lagging chromosomes, formation of
anaphase bridges, and fragmentation (Table B.4.5).
Further investigations on the mitotic effect of 2,4-dichlorophenol
on Vicia faba were later conducted by Amer and Ali (1974). Fifteen- or
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102
TABLE B.4.3. LEVELS OF 2,4-DICHLOROPHENOL AND 2,4-D IN
AERIAL PORTIONS OF PLANTS AFTER TREATMENT WITH 2,4-D
Plant
Kidney bean (Phaseolus vulgaris)
Soybean (Glycine T^T)
Pea (Pisian satimari)
Bromegrass (Bromus sp.)
Wild oat (A-jena fairua)
Yellow foxtail (Setaria glauca)
Barley (Bordeum vulgare)
Timothy (Phlewn pratense)
Orchard grass (Daetylis glomeratd)
Residue levels
(yg/g fresh wt)a
2,4-Dichlo-
rophenol
0.4
<0.1
0.2
0.2
0.3
0.1
0.4
0.5
0.2
2,4-D
60.1
18.5
31.4
13.7
33.3
35.4
34.5
40.6
38.7
Determined 72 hr after treatment with 2,4-D in 50%
acetone at a rate of 1.0 kg/ha.
Source: Adapted from Steen et al., 1974, Table 1,
p. 26. Reprinted by permission of the publisher.
TABLE B.4.4. LEVELS OF 2,4-DICHLOROPHENOL AND 2,4-D DJ
PLANTS WHOSE ROOTS WERE TREATED WITH 2,4-D
Plant
Kidney bean (Phaseolus vulgaris)
Soybean (Glycine max)
Pea (Pisum satiimm)
Bromegrass (.Bromus sp.)
Wild oat (Avena fatua)
Yellow foxtail {Setaria. gZauoa)
Barley (Hovdewn vulgare)
Timothy (Phleum pratense)
Orchard grass (Daetylis glomerate)
Residue levels
(ug/g fresh wt)a
2,4-Dichlo-
rophenol
1.3
0.3
0.4
0.4
0.7
0.4
1.0
1.6
0.3
2,4-D
75.0
61.0
70.0
86.8
70.0
89.0
70.0
83.0
57.0
Roots treated with 2,4-D at a. rate of 0.1 mg ml 1
g"1 fresh wt.
Source: Adapted from Steen et al., 1974, Table 3,
p. 26. Reprinted by permission of the publisher.
-------
103
TABLE B.4.5. EFFECT OF 2,4-DICHLOROPHENOL ON MITOTIC
ABNORMALITIES IN ROOT PREPARATIONS OF VICIA FA5A
Cell type and
mitotic stage
Treated with
Control 62.5 mg/liter
2,4-dichlorophenol
Number of dividing cells
Number of abnormal cells
Abnormal cells, 5&
Cells in prophase, %
Cells in metaphase, %
Abnormal cells in metaphase, TT
Cells in anatelophase, %
Abnormal cells in anatelophase, %
Mitotic index
920
4
0.43
55.5
18.4
1.18
26.1
0.83
147
1005
39
3.88
68.6
21.3
10.7
10.1
15.7
95
Determined as ratio of abnormal cells to normal cells x 100.
Source: Adapted from Amer and Ali, 1969, Table 1, p. 534.
Reprinted by permission of the publisher.
35-day-old plants were sprayed daily with 7 ml of aqueous 2,4-dichlorophe-
nol solution containing 0.39 mg 2,4-dichlorophenol per liter. Flower buds
were gathered when the plants were 40 days old and pollen mother cells were
checked for mitotic abnormalities. Abnormalities were detected, and the
effect depended on plant age. Stickiness, lagging chromosomes, and frag-
mentation were the most common abnormalities observed. A higher percentage
of abnormal pollen mother cells was seen in 35-day-old plants than in 15-
day-old plants. Vieia fdba seeds were soaked in water containing 0.39
mg/liter of 2,4-dichlorophenol for 24 hr and planted. Analyses of pollen
mother cells were performed in a manner similar to that described for
sprayed plants (Table B.4.6). Significant increases in the percentage of
abnormal pollen mother cells were noted when 35-day-old plants were sprayed
or when seeds were soaked in a solution of 2,4-dichlorophenol. No signif-
icant increases in the percentage of abnormal pollen mother cells were
noted when 15-day-old plants were sprayed. The possibility of 2,4-dichlo-
rophenol causing pollen grain sterility was also investigated, but no
adverse effects were noted. Effects on yields of the European broad bean
(Vicia fdba) were also studied (Amer and Ali, 1974). Only plants sprayed
at 15 days showed a significant yield decrease. The number of pods per
plant and the weight of seeds per plant decreased over control plants,
which were significant at the 5% level of probability. When later gener-
ations of plants were examined, it was found that the second generation
of these treated plants showed a reduced seed weight per plant, but the
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104
TABLE B.4.6. PERCENTAGE OF ABNORMAL POLLEN MOTHER CELLS
AFTER TREATMENT OF VICIA FABA WITH 2,4-DICHLOROPHENOL
Treatment
Seeds soaked in water
15- or 35-day-old plants sprayed with water
Number
of plants
5
7
Abnormal pollen
mother cells
(mean %)
0.27
0.68
Seeds soaked for 24 hr in solution containing
0.39 mg/liter 2,4-dichlorophenol
15-day-old plants sprayed daily for five days with
7-ml solution containing 0.39 mg/liter
2,4-dichlorophenol
35-day-old plants sprayed daily for five days with
7-ml solution containing 0.39 mg/liter
2,4-dichlorophenol
2.24
1.24
4.79
a
Determination made 40 days after planting; values different from control at
the 5% level of probability.
Source: Adapted from Amer and Ali, 1974, Table 1, p. 634.
permission of the publisher.
Reprinted by
number of pods per plant did not differ from the controls.
found in the third generation.
No effect was
Two distinguishable effects on mitoses of 2,4-dichlorophenol-treated
pea seedlings (Pisim sativiffri) were observed by Miihling et al. (1960). The
primary roots of the seedlings were suspended for 8 to 12 hr at 22.5°C in a
nutrient bath containing 2,4-dichlorophenol. The plants were removed and
the roots were analyzed for cytological effects. At 2,4-dichlorophenol
concentrations greater than 60 mg/liter, spindle formation was inhibited,
resulting in chromosome configurations very similar to those produced by
the mitotic inhibitor colchicine. Also, the onset of cell division was
inhibited.
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105
SECTION B.4
REFERENCES
1. Amer, S. M., and E. M. All. 1969. Cytological Effects of Pesti-
cides: IV. Mitotic Effects of Some Phenols. Cytologia 34:533-540.
2. Amer, S. M., and E. M. All. 1974. Cytological Effects of Pesti-
cides: V. Effects of Some Herbicides on Vic-ia fdba. Cytologia
39(4):633-643.
3. Blackman, G. E. , M. H. Parke, and G. Carton. 1955a. The Physio-
logical Activity of Substituted Phenols: I. Relationships between
Chemical Structure and Physiological Activity. Arch. Biochem.
Biophys. 54:45-54.
4. Blackman, G. E. , M. H. Parke, and G. Carton. 1955&. The Physiolog-
ical Activity of Substituted Phenols: II. Relationships between
Physiological Properties and Physiological Activity. Arch. Biochem.
Biophys. 54:55-71.
5. Bristol, D., L. Cook, M. Koterba, and D. C. Nelson. 1974. Deter-
mination of Trace Residues of 2,4-D and 2,4-Dichlorophenol in
Potato Tubers (abstract). Abstr. Pap. Am. Chem. Soc. 1974:44.
6. Chkanikov, D. I., A. M. Makeev, N. N. Pavlova, E. N. Artemenko, and
V. P. Dubovoi. 1976. Role of 2,4-D Metabolism in the Manifesta-
tion of Plant Resistance to This Herbicide. Agrokhimiya 2:120-126.
7. Dexter, A. G., F. W. Slife, and H. S. Butler. 1971. Detoxifica-
tion of 2,4-D by Several Plant Species. Weed Sci. 19(6):721-726.
8. Dinant, M., T. Caspar, and T. Avella. 1967- Interaction du 2,4-
dichlorophe"nol et de 1'eau oxyge'ne'e dans la destruction enzymatique
de 1'acide B-indolyace'tique (Interaction of 2,4-Dichlorophenol and
Hydrogen Peroxide in the Enzymatic Destruction of 3-Indolyl Acetic
Acid). Experientia 23(3):180-181.
9. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons,
Interscience Publishers, New York. pp. 325-338.
10. Goldacre, P. L., and A. W. Galston. 1953. The Specific Inhibition
of Catalase by Substituted Phenols. Arch. Biochem. Biophys.
43:169-175.
11. Isensee, A. R., and G. E. Jones. 1971. Absorption and Transloca-
tion of Root and Foliage Applied 2,4-Dichlorophenol, 2,7-Dichloro-
dibenzo-p-dioxin, and 2,3,7,8-Tetrachlorodibenzo-p-dioxin. J.
Agric. Food Chem. 19(6):1210-1214.
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106
12. Luckwill, L. C. , and C. P. Lloyd-Jones. 1960. Metabolism of Plant
Growth Regulators: II. Decarboxylation of 2,4-Dichlorophenoxy-
acetic Acid in Leaves of Apple and Strawberry. Ann. Appl. Biol.
48(3):626-636.
13. Miller, L. P. 1941. Induced Formation of a 3-Gentiobioside in
Tomato Roots. Contrib. Boyce Thompson Inst. 11(6):387-391.
14. Muhling, G. N., J. Van't Hof, G. B. Wilson, and B. H. Grigsby.
1960. Cytological Effects of Herbicidal Substituted Phenols.
Weeds 8:173-181.
15. Psenakova, T., J. Kolek, M. Psenak, and P. Kovacs. 1971. Relation
of Phenolic Compounds to lAA-Oxidase System Isolated from Maize
Roots (Zea mays). Biologia (Bratislava) 26(3):177-185.
16. Sokolov, M. A., L. L. Knyr, B. P. Strekozov, V. D. Agarkov, A. P.
Chubenko, and B. A. Kryzkho. 1974. Behavior of Some Herbicides
during Rice Irrigation. Agrokhimiya 3:95-106.
17. Steen, R. C., I. R. Schultz, D. C. Zimmerman, and J. R. Fleeker.
1974. Absence of 3-(2,4-Dichlorophenoxy)propionic Acid in Plants
Treated with 2,4-Dichlorophenoxyacetic Acid. Weed Res. 14(1):23-28.
18. Taniguchi, M., M. Yamaguchi, and Y. Satomura. 1973. Regulation of
lAA-Metabolizing Enzymes in Plants by an Anti-auxin, 3-(4-Phenyl-
carbostyriloxy)acetic acid. Agric. Biol. Chem. 37(4):819-825.
19. Volynets, A. P., and L. A. Pal'chenko. 1972. Interaction of
Herbicides with Phytohormones. Dokl. Akad. Nauk B. SSR 16(10):
930-933.
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B.5 BIOLOGICAL ASPECTS IN WILD AND DOMESTIC ANIMALS
B.5.1 BIOLOGICAL ASPECTS IN BIRDS AND MAMMALS
No information was found on the metabolism or physiological effects
of 2-chlorophenol or 2,4-dichlorophenol in birds or mammals which were
directly exposed to either compound. However, a limited number of reports
discuss the appearance of 2,4-dichlorophenol in the tissues of mammals fol-
lowing exposure to related compounds such as 2,4-dichlorophenoxyacetic acid
(2,4-D). Because most of these studies were conducted with experimental
animals under laboratory conditions, the data are examined in Section B.6.
Reports on the formation of 2,4-dichlorophenol by 2,4-D or nemacide degra-
dation in domestic animals are included in Section B.5.1.1.2.
B.5.1.1 Metabolism
B.5.1.1.1 Uptake and Absorption — No reports were found on the up-
take and absorption of 2-chlorophenol or 2,4-dichlorophenol in birds or
mammals.
B.5.1.1.2 Transport and Distribution — No information is available on
the transport and distribution of 2-chlorophenol in birds or mammals. The
tissue distribution of 2,4-dichlorophenol in sheep and cattle fed 2,4-D
was determined by Clark et al. (1975). The 2,4-D was administered in feed
at levels of 300, 1000, and 2000 mg/kg feed. On the basis that each animal
injested a daily ration of 3% of its body weight, these levels were equiv-
alent to 9, 30, and 60 mg/kg body weight daily respectively. The animals
were maintained on a diet containing 2,4-D for 28 days, and tissue samples
were analyzed for 2,4-D and 2,4-dichlorophenol residues at the end of this
period (Table B.5.1). 2,4-Dichlorophenol was not detected in muscle and
fat; however, liver and kidney tissues contained substantial levels of
2,4-dichlorophenol. Withdrawal from 2,4-D treatment for one week before
the sheep were killed resulted in a significant reduction in the residue
level in the kidney, but the liver retained most of the 2,4-dichlorophenol
which had accumulated. Because 2,4-D is probably detoxified in the liver
following administration, high levels of 2,4-dichlorophenol are not sur-
prising. It is difficult, however, to draw any conclusions from these data
regarding the fate of 2,4-dichlorophenol administered directly to domestic
animals. The authors noted that sheep and cattle ingesting 2,4-D generally
ate less feed, gained weight more slowly, and had less efficient feed con-
version ratios than control animals; however, it is not known whether the
2,4-dichlorophenol was responsible for the general weakening of condition.
The presence of 2,4-dichlorophenol in the animals may have resulted from
hydrolysis of 2,4-D by rumen microorganisms or by enzymatic processes with-
in the animal, but no conclusive evidence for either of these pathways was
presented. Bjerke et al. (1972) looked for 2,4-dichlorophenol in the milk
and cream from cows dosed with 2,4-D, but no 2,4-dichlorophenol was de-
tected when the cows were fed diets containing as much as 1000 mg 2,4-
dichlorophenol per kilogram feed for two or three weeks.
107
-------
108
TABLE B.5.1. RESIDUES OF 2,4-D AND 2,4-DICHLOROPHENOL
IN SHEEP AND CATTLE FED 2,4-D FOR 28 DAYS
Daily dose
A • 1 °f 2>4~D
Tissue Animal , /,
(mg/kg
body wt)
Muscle Sheep
Cattle
Fat Sheep
Cattle
Liver Sheep
Cattle
Kidney Sheep
Cattle
60
60a
9
30
60
60
60a
9
30
60
60
60a
9
30
60
60
60a
9
30
60
Residues found
(mg/kg tissue)
2,4-D
0.06
<0.05
<0.05
<0.05
0.07
0.10
0.15
0.13
0.45
0.34
0.98
0.29
<0.05
0.14
0.23
9.17
0.37
2.53
8.67
10.9
2 , 4-Dichlo-
rophenol
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
0.16
0.15
0.11
0.59
0.31
0.26
0.07
0.56
1.17
1.06
Animals dosed with 2,4-D for 28 days and with-
drawn from 2,4-D exposure for seven days before
sampling.
Source:
III, p. 576.
Adapted from Clark et al., 1975, Table
Reprinted by permission of the publisher.
Sherman, Beck, and Herrick (1972) studied the production of 2,4-
dichlorophenol in laying hens following administration of nemacide [0-
(2,4-dichlorophenyl)0,0-diethyl phosphorothioate] administered at levels
of 50, 100, 200, and 800 mg/kg feed over a 55-week period. The animals
were then returned to a normal diet and tissues were analyzed for 2,4-
dichlorophenol residues after 5, 7, 10, 14, and 21 days. No residues of
2,4-dichlorophenol were found in the fat or breast muscle of hens treated
with nemacide. However, 2,4-dichlorophenol was found in the liver and egg
yolk of these hens (Table B.5.2) at levels of <0.12 to 0.61 ppm. Decreas-
ing concentrations of 2,4-dichlorophenol in the liver were noted in animals
fed lower doses of nemacide. 2,4-Dichlorophenol was detected in the livers
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109
TABLE B.5.2. RESIDUES OF 2,4-DICHLOROPHENOL IN LAYING HENS FED
DIETS CONTAINING NEMACIDE [<9-2,4-DICHLOROPHENYL)0,<9-DIETHYL
PHOSPHOROTHIOATE] FOR 55 WEEKS
Nemacide Time after
in feed exposure^
(mg/kg) (days)
800 0
5
7
10
14
21
200 0
5
7
10
14
21
100 0
5
7
10
14
21
50 0
5
7
10
14
21
2,4-Dichlorophenol residues in tissues
(mg/kg)
Mean
0.47
0.50
0.27
0.19
0.38
0.30
0.14
0.36
0.26
0.56
0.14
<0.052
0.31
0.18
0.055
<0.052
Liver
Range
0.14-0.68
0.25-0.75
0.056-0.48
0.11-0.27
0.31-0.44
0.24-0.35
0.099-0.18
0.071-0.64
0.25-0.26
<0. 052-0. 33
0.16-0.46
0.14-0.22
<0. 052-0. 11
Egg yolk
Mean Range
0.61 0.34-0.75
0.27
<0.12
0.15 0.12-0.17
0.13
<0.12
0.15 <0. 12-0. 21
<0.12
<0.12
<0.12
<0.12
<0.12
aHens returned to nemacide-free diets at 55 weeks and 2,4-dichlo-
rophenol residues determined 0 to 21 days thereafter.
Source: Adapted from Sherman, Beck, and Herrick, 1972, Table
VIII, p. 623. Reprinted by permission of the publisher.
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110
for as long as 21 days following removal from treated feed in hens treated
with high nemacide levels. The liver levels increased only from 0.31 ppm
to 0.47 ppm (increase of 34%) on day 0, even though there was a 16-fold
increase in dose (50 to 800 mg/kg).
B.5.1.1.3 Biotransformation — No reports were found on the biotrans-
formation of 2-chlorophenol or 2,4-dichlorophenol in birds or mammals.
B.5.1.1.4 Elimination — No information was found on the elimination
of 2-chlorophenol or 2,4-dichlorophenol in birds or mammals.
B.5.1.2 Effects
No studies were found on the effects of 2-chlorophenol or 2,4-
dichlorophenol in birds or mammals.
B.5.2 BIOLOGICAL ASPECTS IN FISH AND OTHER AQUATIC ORGANISMS
B.5.2.1 Metabolism
B.5.2.1.1 Uptake and Absorption — Apparently, no data exist on the
uptake and absorption of 2-chlorophenol and 2,4-dichlorophenol in aquatic
organisms. However, from toxicological information (Section B.5.2.2), it
is assumed that aquatic organisms can assimilate these chlorophenols. The
route and mechanisms of entry and the factors which control rate and extent
of uptake by aquatic organisms have not been determined.
B.5.2.1.2 Transport and Distribution — No investigations decribing
the transport mechanism or the mode of distribution of 2-chlorophenol or
2,4-dichlorophenol in aquatic organisms were located.
B.5.2.1.3 Biotransformation — No information was found to delineate
the rate or pathway of metabolism of 2-chlorophenol or 2,4-dichlorophenol
in aquatic organisms.
B.5.2.1.4 Elimination — No data on the elimination of 2-chlorophenol
or 2,4-dichlorophenol from aquatic organisms were found.
B.5.2.2 Effects
B.5.2.2.1 Physiological or Biochemical Role — No evidence suggests
that 2-chlorophenol and 2,4-dichlorophenol perform any normal physiolog-
ical function in aquatic organisms.
B.5.2.2.2 Toxicity
B.5.2.2.2.1 Mechanism of action — The biochemical basis for the
toxicity of 2-chlorophenol to aquatic organisms is unknown. Mitsuda,
Murakami, and Kawai (1963) reported that 2-chlorophenol inhibited oxida-
tive phosphorylation in rat liver mitochondrial preparations, but 40 times
greater concentrations of the compound were required to inhibit oxidative
phosphorylation to the same extent as that found with the potent uncoupler
-------
Ill
2,4-dinitrophenol. Inhibition of oxidative phosphorylation in rat liver
mitochondria has also been demonstrated for 2,4-dichlorophenol (Mitsuda,
Murakami, and Kawal, 1963). It is a much more effective uncoupler than'
2-chlorophenol (see Section B.6 for more details).
B.5.2.2.2.2 General toxicity - Toxicitv data for 2-chlorophenol in
aquatic organisms are sparse. The minimum lethal dose for injection into
frogs has been reported as 0.4 mg/kg body weight (von Oettingen, 1949).
Lammering and Burbank (1960) studied the effect of 2-chlorophenol on the
bluegill (Lepomis macrochirus) and established median tolerance limits
(TL^ — the concentration of 2-chlorophenol in the water that killed 50%
of the test fish in a specified time — of 8.2 mg/liter at 24 hr and 8.1
mg/liter at 48 hr. The authors stated, "Inasmuch as the 24 and 48 hr TLm
values were nearly equivalent, it appears that prolonged exposure to o-
chlorophenol will show little, if any, effects that are attributable to
cumulative toxicity." Such short-term studies do not provide sufficient
data to warrant this conclusion. Gross flesh discoloration was observed
in bluegills which were exposed to 2-chlorophenol concentrations greater
than 11.5 mg/liter. Physiological responses of bluegill and trout in-
cluded rapid and uncoordinated movement, loss of equilibrium, nervous
twitching, and an extremely excitable state in which slight movements
near the aquaria would cause the fish to swim in a violent fashion.
The TL^ for 2-chlorophenol in bluegill and rainbow trout (Salmo
gairdnerii irideus) was also determined by Sletten and Burbank (1972)
(Table B.5.3). Trout were approximately three times as sensitive as blue-
gill to the effects of 2-chlorophenol. Sletten and Burbank (1972) devel-
oped an in vitro method for determining the effect of a toxic substance
on fish tissue. The basis of this technique was to evaluate the effect
TABLE B.5.3. MEDIAN TOLERANCE LIMITS
OF BLUEGILL (LEPOMIS MACROCHIRUS)
AND TROUT (SALMO GAIRDNERII)
TO 2-CHLOROPHENOL
Fish
species
Bluegill
Trout
Length of
exposure
(hr)
24
48
24
48
96
TLOT
(mg/liter)
8.2
8.1
2.8
2.7
2.6
Source: Adapted from Sletten and
Burbank, 1972, Table II, p. 28. Re-
printed by permission of the publisher.
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112
of chemicals on the rate of oxygen utilization by fish tissue in a Warburg
respirometer. Oxygen uptake values for tissues exposed to 2-chlorophenol
were measured in 3-hr runs. The respiratory TL^ in the manometric assay
was defined as that amount of 2-chlorophenol which caused a 50% reduction
in oxygen uptake by the treated tissue when compared with the untreated
tissue. The respiratory TL^ values for the in vitro assay on various trout
tissues are shown in Table B.5.4. The authors suggested that the in vitro
test may serve as a viable alternative to the more time-consuming and dif-
ficult toxicity tests currently used. Kopperman, Carlson, and Caple (1974)
determined the 48-hr TL^ value for 2-chlorophenol in Daphnia magna to be
7.4 mg/liter.
TABLE B.5.4. RESPIRATORY MEDIAN
TOLERANCE LIMITS OF TROUT TISSUES
TO 2-CHLOROPHENOLa
Tissue Respiratory
(mg/g tissue)
Brain 0.8
Liver 0.9
Gill 3.2
The concentration of 2-
chlorophenol which caused a 50%
reduction in oxygen uptake of the
tissue compared with control tis-
sue in a 3-hr run.
Source: Adapted from Sletten,
and Burbank, 1972, Table V, p. 30.
Reprinted by permission of the
publisher.
Only two reports described the toxic effect of 2,4-dichlorophenol
on aquatic organisms. Clowes (1951) reported that 2,4-dichlorophenol
affected oxygen consumption and cell division in fertilized sea urchin
eggs (Arbacia punctulatd) . At a concentration of 16.3 mg/liter, 2,4-
dichlorophenol-treated sea urchin eggs consumed approximately twice as
much oxygen as control eggs, and this phenomenon was accompanied by a
dramatic increase in the rate of cell division. At a limiting concentra-
tion of 10.3 mg/liter, a decreased rate of cell division was initiated in
treated eggs; at 163 mg/liter, cell division ceased entirely. The 48-hr
TLm °f 2,4-dichlorophenol to Daphnia magna was reported as 2.6 mg/liter
(Kopperman, Carlson, and Caple, 1974).
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113
SECTION B.5
REFERENCES
1. Bjerke, E. L., J. L. Herman, P. W. Miller, and J. H. Wetters. 1972.
Residue Study of Phenoxy Herbicides in Milk and Cream. J. Agric.
Food Chem. 20(5):963-967.
2. Clark, D. E., J. S. Palmer, R. D. Radeleff, H. R. Crookshank, and
F. M. Farr. 1975. Residues of Chlorophenoxy Acid Herbicides and
Their Phenolic Metabolites in Tissues of Sheep and Cattle. J.
Agric. Food Chem. 23(3):573-578.
3. Clowes, G.H.A. 1951. The Inhibition of Cell Division by Substitu-
ted Phenols with Special Reference to the Metabolism of Dividing
Cells. Ann. N.Y. Acad. Sci. 51:1409-1431.
4. Kopperman, H. L. , R. M. Carlson, and R. Caple. 1974. Aqueous Chlo-
rination and Ozonation Studies: I. Structure-Toxicity Correlations
of Phenolic Compounds to Daphnia magma. Chem. Biol. Interact.
9(4):245-251.
5. Lammering, M. W. , and N. C. Burbank, Jr. 1960. The Toxicity of
Phenol, 0-Chlorophenol, and o-Nitrophenol to Bluegill Sunfish. Proc.
Ind. Waste Conf. 15:541-555.
6. Mitsuda, H., K. Murakami, and F. Kawai. 1963. Effect of Chloro-
phenol Analogues on the Oxidative Phosphorylation in Rat Liver
Mitochondria. Agric. Biol. Chem. 27(5):366-372.
7. Sherman, M. , J. Beck, and R. B. Herrick. 1972. Chronic Toxicity and
Residues from Feeding Nemacide [<9-(2,4-Dichlorophenyl)C>,C>-diethyl
Phosphorothioate] to Laying Hens. J. Agric. Food Chem. 20(3):617-624.
8. Sletten, 0., and N. C. Burbank, Jr. 1972. A Respirometric Screening
Test for Toxic Substances. Eng. Bull. Purdue Univ. Eng. Ext. Ser.
141(1):24-32.
9. von Oettingen, W. F. 1949. The Halogenated Phenols. In: Phenol
and Its Derivatives: The Relation between Their Chemical Constitu-
tion and Their Effect on the Organism. National Institutes of Health
Bulletin No. 190. U.S. Public Health Services, Washington, D.C.
pp. 193-220.
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B.6 BIOLOGICAL ASPECTS IN HUMANS
B.6.1 METABOLISM
B.6.1.1 Uptake and Absorption
No data on the routes or rates of entry of 2-chlorophenol in humans
were found. Administration of 2-chlorophenol to experimental animals sub-
cutaneous ly, intravenously, intraperitoneally, or orally may result in
death (Section B.6.2), indicating that 2-chlorophenol is absorbed by the
organism. It is not known if 2-chlorophenol is absorbed by the respiratory
route. According to Doedens (1963), the monochlorophenols are corrosive
to the skin and eyes and are absorbed readily through the skin in toxic
amounts. Furthermore, the vapors or dusts are reportedly irritating and
toxic. 2-Chlorophenol was not specifically discussed; therefore, its
cutaneous toxicity and respiratory toxicity remain questionable.
Data on the uptake and absorption of 2,4-dichlorophenol in humans
are also sparse. Toxicity to experimental animals has been demonstrated
when the compound is administered by the oral, Intraperitoneal, or sub-
cutaneous routes, indicating absorption into the body by these routes.
Doedens (1963) stated that the dichlorophenols may be somewhat less toxic
than the monochlorophenols and are absorbed less quickly through the skin.
No data directly addressing this question are available.
B.6.1.2 Transport and Distribution
No information on the transport or tissue distribution of 2-chloro-
phenol or 2,4-dichlorophenol was found.
B.6.1.3 Biotransformation
Data on the metabolism of 2-chlorophenol in humans are not available.
Information obtained from experimental animals indicates that 2-chloro-
phenol is excreted primarily in the urine in both free and conjugated
forms. In dogs, 87% of administered 2-chlorophenol was excreted as sul-
furic and glucuronic acid conjugates (von Oettingen, 1949). The urine
from these animals darkened upon standing, which indicates the formation
of polyphenols. Free 2-chlorophenol, as well as the sulfate and glucuro-
nide conjugates of the compound, was detected in rabbit urine after oral
administration of monochlorobenzene (Lindsay Smith, Shaw, and Foulkes,
1972). Unfortunately, the data presented by these investigators do not
allow the calculation of the relative levels of free 2-chlorophenol and
its conjugates. Most of the 2-chlorophenol resulting from chlorobenzene
metabolism, however, was excreted in the conjugated form.
The convulsive action of 2-chlorophenol in mice was studied by Angel
and Rogers (1972). Following intraperitoneal administration of 2-chloro-
phenol, a rapid onset of convulsions was noted. Furthermore, a simple
exponential decay of the convulsive effect indicated that removal from
the central nervous system may occur by a simple chemical reaction. The
114
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115
authors suggested that ortho methylation in the body may be the relevant
detoxification mechanism; however, no information directly addressing this
point is available.
No information on the biotransformation of 2,4-dichlorophenol in
humans is available, nor were reports found on the biotransformation of
2,4-dichlorophenol following administration of the compound directly to
experimental animals. One investigation suggested a detoxification mecha-
nism for 2,4-dichlorophenol in mice following intraperitoneal injection of
1,2,3,4,5,6-hexachlorocyclohexane (Kurihara and Nakajima, 1974). Carbon-
14—labeled hexachlorocyclohexane isomers (y and g) were administered to
mice, and the appearance of metabolites in the urine was monitored. 2,4-
Dichlorophenol and 2,4-dichlorophenol conjugates (sulfate and glucuronide)
were major metabolites of y~ and 6-hexachlorocyclohexane in the mouse.
Free 2,4-dichlorophenol was found in the urine to a lesser extent (Table
B.6.1). The data indicate that following the administration of y-nexachlo-
rocyclohexane, the glucuronide conjugate of 2,4-dichlorophenol was present
to the greatest degree (4% to 5% of the administered hexachlorocylohexane
radioactivity). The sulfate conjugate comprised 1% of the administered
hexachlorocyclohexane radioactivity. After administration of 6-hexachlo-
rocyclohexane, glucuronide and sulfate conjugates were present in the
urine at approximately equal levels. If one assumes that the metabolism
of 2,4-dichlorophenol which results from prior metabolism of another
organic compound parallels the transformation of 2,4-dichlorophenol which
is directly administered to mammals, conjugation to sulfate or glucuronide
appears to be a major metabolic pathway.
TABLE B.6.1. ABUNDANCE OF THE PRINCIPAL URINARY 2,4-DICHLOROPHENOL-CONTAINING
METABOLITES FROM HEXACHLOROCYCLOHEXANE ISOMERS IN THE MOUSE
Abundance of metabolites in urine (% of total metabolites)
Isomer
administered
y-Hexachlorocyclohexane
6-Hexachlorocyclohexane
2,4-Dichlo-
rophenol
glucuronide
4-5
1-2
2,4-Dichlo-
rophenol
sulfate
1
3
Total
2,4-dichlo-
rophenol
conjugates
4-6
4-5
Free
chlorophenols
3
11*
Free acidic compounds; individual compounds not identified.
Source: Adapted from Kurihara, 1975, Table 13, p. 68. Reprinted by permission
of the publisher.
B.6.1.4 Elimination
No data on the elimination of 2-chlorophenol directly administered
to humans or mammals have been found. One study which sheds some light
on the excretion of 2-chlorophenol was reported by Lindsay Smith, Shaw,
and Foulkes (1972). Following administration of chlorobenzene to rabbits,
-------
116
2-chlorophenol appeared in the urine in both free and conjugated forms.
Unfortunately, it is not possible to calculate the relative amounts of
free and conjugate forms of 2-chlorophenol. Excretion primarily through
the urine appears to be a likely possibility. Following administration
of 2-chlorophenol to dogs, 87% of the compound was excreted in conjugation
with sulfuric and glucuronic acids (von Oettingen, 1949). The urine sam-
ples on standing became darker in color, indicating the formation of
polyphenols following excretion.
Elimination of 2,4-dichlorophenol from mammals can only be inferred
from data on the excretion of 2,4-dichlorophenol following degradation of
other compounds. After administration of lindane, Karapally, Saha, and
Lee (1973) noted that 4.4% of total ether-soluble metabolites in rabbit
urine was 2,4-dichlorophenol; the data do not allow calculation of urinary
excretion rates. Similarly, administration of nemacide [0-(2,4-dichloro-
phenyl)0,0-diethyl phosphorothioate] to rats caused the appearance of
2,4-dichlorophenol in urine (Shafik, Sullivan, and Enos, 1973). Nemacide
in peanut oil was administered to rats by gavage (feeding with a stomach
tube) once a day for three days. The 2,4-dichlorophenol content of the
urine was determined until the compound no longer appeared. Following
administration of 1.6 mg of nemacide, 67% of the compound appeared in
the urine as 2,4-dichlorophenol within three days. When rats were dosed
with smaller amounts of nemacide (0.16 mg), 70% of the administered dose
appeared in the urine as 2,4-dichlorophenol in one day. Apparently,
excretion of 2,4-dichlorophenol was completed during these periods.
Although investigations providing information on the appearance of
2-chlorophenol or 2,4-dichlorophenol in mammals as a result of metabolism
of other organic compounds were conducted primarily to understand the
mechanisms of detoxification of foreign compounds, they also offer infor-
mation on an alternative source of exposure to chlorophenols by mammals.
The extent of this exposure is speculative; compounds other than those
described may be transformed to 2-chlorophenol or 2,4-dichlorophenol in
mammals, including humans. As discussed above, 2-chlorophenol was detected
as a minor metabolite of chlorobenzene metabolism in rabbits (Lindsay
Smith, Shaw, and Foulkes, 1972). Another investigation (Selander, Jerina,
and Daly, 1975) demonstrated that chlorobenzene was converted to a mixture
of 2-, 3-, and 4-monochlorophenol in perfused rat liver preparations.
Three different monochlorophenols were produced, and evidence showed that
three enzyme systems catalyzed the hydroxylation of chlorobenzene to mono-
chlorophenols. 2,4-Dichlorophenol has been detected as a metabolite of
y- and (3-hexachlorocyclohexane in mice, lindane (not less than 99% of the
y isomer of hexachlorocyclohexane) in the rabbit, and nemacide in the rat
(Karapally, Saha, and Lee, 1973; Shafik, Sullivan, and Enos, 1973; Rurihara
and Nakajima, 1974). Exposure of animals or humans to these compounds is
more likely than direct exposure to 2-chlorophenol or 2,4-dichlorophenol.
Neither 2-chlorophenol nor 2,4-dichlorophenol is widely used, and exposure
is probably limited to workers in the manufacturing industry. Exposure
to compounds such as lindane and nemacide is more likely because they
have been widely used as pesticides.
-------
117
B.6.2 EFFECTS
B.6.2.1 Physiological or Biochemical Role
Humans do not appear to have a normal physiological requirement
for 2-chlorophenol. Similarly, no physiological requirement for 2,4-
dichlorophenol in mammalian systems has been demonstrated. However, it
has been shown that the enzymatic oxidation of NADH in various tissues
is stimulated by the presence of 2,4-dichlorophenol (Coleman and Bever,
1968). This catalytic requirement for in vitro enzyme assay systems is
relatively nonspecific; apparently, the presence of an aromatic hydroxy
group is all that is required. The importance of this phenomenon in the
in vitro situation is not known.
B.6.2.2 Toxicity
B.6.2.2.1 Mechanism of Action — The mechanism of toxic action of
2-chlorophenol is not well characterized. 2-Chlorophenol appears to
uncouple oxidative phosphorylation in rat liver mitochondria (Mitsuda,
Murakami, and Kawai, 1963); however, the effect is relatively weak.
Mitsuda, Murakami, and Kawai (1963) noted that 2-chlorophenol was the
weakest uncoupler of nine chlorophenols tested. In addition, Parker (1958)
noted that 2-chlorophenol appeared to uncouple oxidative phosphorylation,
but during the course of its action the uptake of oxygen was greatly inhib-
ited in rat liver mitochondrial preparations. This effect contrasts with
that of the strong uncouplers 2,4-dinitrophenol and pentachlorophenol;
these compounds uncouple oxidative phosphorylation without a concomitant
decrease in oxygen uptake. Farquharson, Gage, and Northover (1958) studied
the biological action of a series of chlorinated phenols and noted that
toxicity increased with increased chlorination; the convulsant action of
phenol was replaced by the poisoning characteristic of dinitrophenol.
Tremors and convulsions in rats were reported by Farquharson, Gage, and
Northover (1958) after 2-chlorophenol was injected intraperitoneally.
Tremors appeared in 40 to 120 sec. When the tremors increased in sever-
ity, intermittent convulsions developed and the rat usually fell on its
side with loss of righting reflexes.
Farquharson, Gage, and Northover (1958) also examined the effect of
2-chlorophenol on the oxygen uptake of rat brain homogenates. 2-Chloro-
phenol caused no stimulation of oxygen uptake at concentrations ranging
from 10~6 to 10~3 M. Angel and Rogers (1972) studied the convulsive
activity of a series of organic compounds, including 2-chlorophenol. The
compounds were administered intraperitoneally to anesthetized mice. 2-
Chlorophenol caused myoclonic convulsions (i.e., alternate contraction
and relaxation of groups of muscles). Dosages of the compounds needed
to cause convulsions in 50% of the treated animals were 0.77 millimole/kg
(99 mg/kg) for 2-chlorophenol and 1.04 millimoles/kg (98 mg/kg) for phenol.
Thus, 2-chlorophenol was 1.3 to 1.4 times more potent than phenol, which
has a well-documented convulsive action in mammals. The biochemical mech-
anism for this action is unknown.
-------
118
No evidence suggests that 2,4-dichlorophenol has a convulsive effect
on mammals, but various enzymes as well as the process of oxidative phos-
phorylation have been affected. Stockdale and Selwyn (1971) demonstrated
that 2,4-dichlorophenol inhibited the activity of lactate dehydrogenase
and hexokinase in an in vitro system. These investigators suggested that
this inhibition resulted from the binding of 2,4-dichlorophenol to the
enzyme at a site which normally binds the adenine group in the substrate.
The physiological significance of this enzyme inhibition is not known.
2,4-Dichlorophenol also has inhibited oxidative phosphorylation in rat
liver mitochondria and rat brain homogenate preparations (Farquharson,
Gage, and Northover, 1958; Parker, 1958; Mitsuda, Murakami, and Kawai,
1963). According to Farquharson, Gage, and Northover (1958), oxygen up-
take in rat brain homogenates peaks (70% above control values) at a 2,4-
dichlorbphenol concentration of 2.5 x ICT** M. Mitsuda, Murakami, and
Kawai (1963) calculated that a concentration of 4.2 x 10~s M 2,4-dichlo-
rophenol inhibited oxidative phosphorylation by 50% in rat liver mitochon-
drial preparations; this value was roughly intermediate among the nine
chlorophenols tested. The inhibition was approximately twofold weaker
than that of 2,4-dinitrophenol, a strong uncoupler of oxidative phosphory-
lation. It is not clear how this effect on oxidative phosphorylation
contributes to the toxicity of 2,4-dichlorophenol in mammals, but it seems
likely that it may be responsible for the toxicity of the compound.
B.6.2.2.2 General Toxicity—No information exists on the toxicity
of 2-chlorophenol to humans, but toxicity has been documented in experi-
mental animals. Lethal dosages for various experimental animals are
compiled in Table A.6.4. Signs of 2-chlorophenol intoxication in rats
are similar whether the compound is administered subcutaneously, intra-
peritoneally, or orally. The toxicological picture includes restless-
ness and increased rate of respiration within a few minutes following
administration. Somewhat later motor weakness develops and tremors and
convulsions induced by noise or touch occur. Eventually, dyspnea and
coma appear and continue until death (Farquharson, Gage, and Northover,
1958). Following fatal poisoning, the pathology of the rat includes
marked kidney injury, the presence of red blood cell casts in the tubules,
fatty infiltration in the liver, and hemorrhages in the intestine (Deich-
mann and Keplinger, 1963). Bubnov, Yaphizov, and Ogryzkov (1969) reported
a similar pathological picture in the blue fox and the mouse. Lethal con-
centrations of 2-chlorophenol caused fatty degeneration of the liver,
renal granular dystrophy, and necrosis of the stomach and intestinal
mucosa.
The toxicology of 2,4-dichlorophenol is poorly documented. It is
apparently moderately toxic to animals (Sax, 1975). Only a few LD50
values for 2,4-dichlorophenol in experimental animals have been pub-
lished (Table A.6.4). A comprehensive study of the chronic toxicity of
2,4-dichlorophenol in mice was conducted by Kobayashi et al. (1972).
Male mice were fed a diet containing the compound for six months.
Various parameters, including average body weight, food consumption,
organ weight, and histological findings in major organs, were measured
throughout the treatment period. No adverse changes in the behavior,
growth rate, or blood glutamic oxaloacetate and glutamic or pyruvate
-------
119
TABLE B.6.2. HISTOLOGICAL CHANGES IN MAJOR ORGANS OF MALE MICE
(SEVEN ANIMALS PER GROUP) FED 2,4-DICHLOROPHENOL DAILY FOR SIX MONTHS
Organ
Observation
Control
Number of changes
100 mg/kg
2,4-dichlo-
rophenol
230 mg/kg
2,4-dichlo-
rophenol
Heart
Liver
Kidneys
Spleen
Localized degenerative
changes in myocardium 1
Small round cell
infiltration 0
Swelling of hepatic cell 0
Unequal size of hepatic
cell 0
Dark cell 1
Focal necrosis 1
Interstitial reaction 0
Small round cell
infiltration 4
Collapse of glomerulus 0
Interstitial cell infil-
tration 1
Atrophic change in
lymphatic layer of
0
0
0
0
0
2
3
1
2
1
1
2
0
0
3
1
Adrenal glands
white pulps
Thinner cortex
0
0
0
0
1
2
Source: Adapted from Kobayashi et al., 1972, Table 8, p.
permission of the publisher.
360. Reprinted by
transaminase levels were found in mice receiving up to a maximum daily
dose of 230 mg/kg. Minor histological changes occurred in the liver of
animals receiving this dose (Table B.6.2). The authors concluded that
2,4-dichlorophenol is a safe substance and set a daily dose of 100 mg/kg
as a maximum no-effect level in mice.
Only one report suggested that 2,4-dichlorophenol may have adverse
effects in humans. Bleiberg et al. (1964) reported 29 cases of acquired
chloracne and 11 cases of porphyria in workers involved in the manu-
facture of 2,4-dichlorophenol and 2,4,5-trichlorophenol. The patients
were exposed to a group of basic chemicals including acetic acid, phenol,
monochloroacetic acid, sodium hydroxide, 2,4-dichlorophenol, and 2,4,5-
trichlorophenol in the occupational environment. The agents responsible
for the symptoms cannot be determined clearly, nor can the degree of
involvement of 2,4-dichlorophenol in skin pathology and liver damage be
assessed (Table B.6.3).
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120
TABLE B.6.3. SUMMARY OF DATA FOR 26 WORKERS INVOLVED IN MANUFACTURE OF
2,4-DICHLOROPHENOL AND 2,4,5-TRICHLOROPHENOL
Patient
1
2
3
4C
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Chloracne
Severe
Mild
Mild
Severe
Mild
Mild
Mild
Severe
Mild
Moderate
Severe
None
None
None
Moderate
Moderate
Mild
Moderate
Severe
Mild
None
None
Mild
None
None
None
Hyperpigmentation
Mild
None
Mild
Mild
None
None
Mild
Moderate
Mild
Moderate
Moderate
None
None
None
Mild
Moderate
Mild
Moderate
Marked
Mild
None
None
None
None
None
None
Hirsutism
Moderate
None
None
Mild
Mild
None
None
Severe
Mild
Moderate
Moderate
None
None
None
Moderate
Marked
None
Marked
None
Moderate
None
None
None
None
None
None
Urine
uroporphyrins
Positive
None
None
None
Positive
None
Positive
None
None
None
None
None
None
Positive
None
None
None
None
Positive
Positive
None
None
None
None
Positive
Positive
Chemical
contact*
Moderate
Severe
Severe
Severe
Severe
Moderate
Moderate
Moderate
Moderate
Severe
Moderate
Severe
Severe
Moderate
Moderate
Severe
Mild
Mild
Mild
Mild
Mild
Mild
Mild
Mild
Mild
Mild
Skin
fragility
Positive
Negative
Negative
Positive
Positive
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Positive
Positive
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Negative
Severity of chloracne judged on presence of comedones, epidennoid cysts, and furuncles and
pustules.
^Extent of exposure difficult to judge because of variables such as personal hygiene and
work habits.
Q
Brief period of employment.
Source: Adapted from Bleiberg et al., 1964, p. 795. Reprinted by permission of the
publisher.
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121
B.6.2.2.3 Carcinogenicity — Repeated applications of phenol and
some substituted phenols reportedly can promote the appearance of skin
tumors in mice following a single initiating dose of dimethyIbenzanthra-
cene (Boutwell and Bosch, 1959). Tumors also developed in mice (not ex-
posed to dimethylbenzanthracene) treated with phenol alone for long
periods. When 2-chlorophenol and 2,4-dichlorophenol were tested for
tumorigenicity and tumor-promoting activity in a similar system (Boutwell
and Bosch, 1959), a tumor-promoting activity was present.^No evidence
exists that either 2-chlorophenol or 2,4-dichlorophenol may cause tumors
in the absence of an initiator (i.e., dimethylbenzanthracene). Both
2-chlorophenol and 2,4-dichlorophenol possessed approximately the same
activity in promoting tumor formation as phenol (Table B.6.4). Both
benign and malignant tumors were formed. The hazardous effect to humans
exposed to either of these compounds is not known. Protracted skin
contact is not recommended because of the potential for tumor formation
and because both compounds are primary skin irritants.
TABLE B.6.4. APPEARANCE OF SKIN TUMORS IN MICE TREATED CUTANEOUSLY WITH PHENOLS
FOLLOWING A CUTANEOUS DOSE OF 0.3% DIMETHYLBE'IZANTHRACENE IN ACETONE
Time animals
Treatment examined
(weeks)
Number of mice
(survivors/ total)
Survivors
with papilloma
Survivors
with
epithelial
carcinoma
Benzene control
10% phenol in benzene, no
dimethylbenzanthracene
20% phenol in acetone
20% phenol in benzene
20% 2-chlorophenol in
benzene
20% 2,4-dichlorophenol in
benzene
12
20
12
24
15
15
12/12
24/30
21/24
10/33
31/35
27/33
0
33
58
100
61
48
13
5
20
10
11
All received dimethylbenzanthracene except where stated.
Source: Adapted from Boutwell and Bosch, 1959, Table 2, pp. 418-420. Reprinted by per-
mission of the publisher.
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122
SECTION B.6
REFERENCES
1. Angel, A., and K. J. Rogers. 1972. An Analysis of the Convulsant
Activity of Substituted Benzenes in the Mouse. Toxicol. Appl. Phar-
macol. 21(2):214-229.
2. Bleiberg, J., M. Wallen, R. Brodkin, and I. L. Applebaum. 1964.
Industrially Acquired Porphyria. Arch. Dermatol. 89:793-797.
3. Boutwell, R. K., and D. K. Bosch. 1959. The Tumor-Promoting Action
of Phenol and Related Compounds for Mouse Skin. Cancer Res. 19:413-
424.
4. Bubnov, W. D., F. N. Yaphizov, and S. E. Ogryzkov. 1969. Toxic
Properties of Activated o-Chlorophenol for White Mice and Blue Foxes.
Tr. Vses. Nauchno Issled. Inst. Vet. Sanit. Ektoparazitol. 33:258-263.
5. Coleman, R. L., and A. T. Bever. 1968. Purification and Properties
of Dichlorophenol-Stimulated NADH Oxidase from Rat Uterus. Biochim.
Biophys. Acta 151(1):267-269.
6. Deichmann, W. B., and M. L. Keplinger. 1963. Phenols and Phenolic
Compounds. In: Industrial Hygiene and Toxicology, 2nd ed., Vol. 2,
Toxicology, D. W. Fassett and D. D. Irish, eds. John Wiley and Sons,
Interscience Publishers, New York. pp. 1363-1408.
7. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons, Inter-
science Publishers, New York. pp. 325-338.
8. Farquharson, M. E., J. C. Gage, and J. Northover. 1958. The Bio-
logical Action of Chlorophenols. Br. J. Pharmacol. 13:20-24.
9. Karapally, J. C., J. G. Saha, and Y. W. Lee. 1973. Metabolism of
Lindane-^C in the Rabbit: Ether-Soluble Urinary Metabolites. J.
Agric. Food Chem. 21(5):811-818.
10. Kobayashi, S., S. Toida, H. Kawamura, H. S. Chang, T. Fukuda, and
K. Kawaguchi. 1972. Chronic Toxicity of 2,4-Dichlorophenol in
Mice: A Simple Design for the Toxicity of Residual Metabolites of
Pesticides. Toho Igakkai Zasshi 19(3-4):356-362.
11. Kurihara, N. 1975. Urinary Metabolites from y- and 3-BHC in the
Mouse: Chlorophenol Conjugates. Environ. Qual. Saf. 4:56-73.
12. Kurihara, N., and M. Nakajima. 1974. Studies on BHC Isomers and
Related Compounds: VIII. Urinary Metabolites Produced from y~
3-BHC in the Mouse: Chlorophenol Conjugates. Pestic. Biochem.
Physiol. 4(2)-.220-231.
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123
13. Lindsay Smith, J. R., B.A.J. Shaw, and D. M. Foulkes. 1972. Mecha-
nisms of Mammalian Hydroxylation: Some Novel Metabolites of Chloro-
benzene. Xenobiotica 2(3):215-226.
14. Mitsuda, H., K. Murakami, and F. Kawai. 1963. Effect of Chlorophenol
Analogues on the Oxidative Phosphorylation in Rat Liver Mitochondria.
Agric. Biol. Chem. 27(5):366-372.
15. Parker, V. H. 1958. Effect of Nitrophenols and Halogenophenols on
the Enzymic Activity of Rat-Liver Mitochondria. Biochem. J. 69:306-
311.
16. Sax, N. I. 1975. Dangerous Properties of Industrial Materials, 4th
ed. Van Nostrand Reinhold Co., New York. pp. 551, 633.
17. Selander, H. G., D. M. Jerina, and J. W. Daly. 1975. Metabolism of
Chlorobenzene and Hepatic Microsomes and Solubilized Cytochrome P-450
Systems. Arch. Biochem. Biophys. 168(1):309-321.
18. Shafik, T. M. , H. C. Sullivan, and H. R. Enos. 1973. Multiresidue
Procedure for Halo- and Nitrophenols: Measurement of Exposure to
Biodegradable Pesticides Yielding These Compounds as Metabolites.
J. Agric. Food Chem. 21(2):295-298.
19. Stockdale, M., and M. J. Selwyn. 1971. Influence of Ring Substit-
uents on the Action of Phenols on Some Dehydrogenases, Phosphokinases
and the Soluble ATPase from Mitochondria. Eur. J. Biochem. 21:416-
423.
20. von Oettingen, W. F. 1949. The Halogenated Phenols. In: Phenol
and Its Derivatives: The Relation between Their Chemical Constitu-
tion and Their Effect on the Organism. National Institutes of Health
Bulletin No. 190. U.S. Public Health Service, Washington, D.C. pp.
193-220.
-------
B.7 ENVIRONMENTAL DISTRIBUTION AND TRANSFORMATION
B.7.1 TRENDS IN PRODUCTION AND USE
Production trends for 2-chlorophenol and 2,4-dichlorophenol are
difficult to assess because data reported to the U.S. International
Trade Commission (U.S. International Trade Commission, 1976) by manu-
facturers are regarded as proprietary. Dow Chemical Company produces
both chemicals; the Monsanto Company manufactures only 2,4-dichloro-
phenol. 2,4-Dichlorophenol production in the United States can be esti-
mated based on the manufacture of the herbicide 2,4-dichlorophenoxyacetic
acid (2,4-D) (Table B.7.1). Data indicate declining production of the
herbicide from 1967 to 1971.
TABLE B.7.1. PRODUCTION OF 2,4-D
COMPOUNDS IN THE UNITED STATES, 1967-1975
Production (metric tons)
Year
0 . _ 2,4-D esters _ . n
2,4-D , - Total
and salts
1967
1968
1969
1970
1971
1972
1973
1974
1975
35,021
35,985
21,373
19,784
b
b
b
b
b
3001
6743
4504
b
b
b
b
b
b
38,022
42,728
25,877
b
24,943°
b
b
b
b
rWithheld to avoid disclosure.
Based on 15,714,000 kg used by
farmers, which represents 63% of the total
usage; excludes exports but includes
imports.
Source: Compiled from U.S. Depart-
ment of Agriculture, 1976.
Important uses which relate to the possible distribution of these
chlorophenols in the environment are discussed in this section. More
detailed discussion of general uses is found in Section B.2. 2-Chloro-
phenol is used principally as an intermediate for the manufacture of
higher chlorophenols (Dow Chemical Company, 1977). Its use as a constitu-
ent of fire retardants has been supplanted by polybrominated biphenyl.
124
-------
125
The direct use of this chemical as a bactericide or germicide is probably
negligible because more effective compounds, such as higher chlorophenols,
have been utilized. The single most important use of 2,4-dichlorophenol
is in the manufacture of pesticides, particularly 2,4-D. The widespread
application of 2,4-D and its derivatives for the control of weeds is
likely the main course by which dichlorophenol finds its way into the
environment. Although 2,4-dichlorophenol has germicidal properties, its
use as such may be negligible.
B.7.2 SOURCES OF POLLUTION
B.7.2.1 Distribution in Air
Reports on the sources and distribution of chlorophenols in the
atmosphere are not available. Because of the lack of atmospheric moni-
toring data for these compounds, their sources, both point and nonpoint,
are only speculative. Potential for large discharges of chlorophenols
into the atmosphere exists in plants where these compounds and hormone-
type pesticides are manufactured. The volatilization of these chemicals
from water, soil, foliage, and impervious surfaces may play an important
role in their dispersal to the atmosphere, but no quantitative data are
available. Furthermore, it might be speculated that incineration could
generate volatile products to the atmosphere through the burning of
containers and trash containing chlorophenols.
B.7.2.2 Distribution in Aquatic Environments
Industrial waste discharge is the principal point source of water
pollution. During the manufacture of chlorophenols and 2,4-D a consider-
able amount of chemical waste is generated as a result of incomplete
reaction of the starting reactants, by-product formation, and incomplete
recovery of desired products. Thus, the wastes contain a mixture of
chlorophenols and other compounds. Waste arising from the manufacture
of phenoxyalkanoic herbicides showed amounts of 2-chlorophenol ranging
from a trace to 6% and of 2,4-dichlorophenol ranging from 11% to 89%
(Sidwell, 1971) (Tables B.7.2 and B.7.3).
Other possible point sources are chemical spills and washing of
containers or drums in which chlorophenols and 2,4-D are stored. Con-
tamination of water with 2-chlorophenol and 2,4-dichlorophenol may arise
from (1) chlorination of phenol present in natural water and primary and
secondary effluents of waste treatment plants (Burttschell et al., 1959;
Eisenhauer, 1964; Manufacturing Chemists Association, 1972), (2) direct
addition of the chemicals or their presence as contaminants or degrada-
tion products of 2,4-D used for aquatic weed control, and (3) wet and
dry atmospheric fallout.
Runoff from urban and agricultural watersheds could be an important
nonpoint source of chlorophenols in aquatic environments. For this to
occur, the primary sources are likely to be contaminants or degradation
products of 2,4-D compounds which are applied widely on croplands, lawns,
and golf courses for the control of weeds. The contribution of runoff
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126
TABLE B.7.2. ANALYSIS OF INDUSTRIAL PLANT WASTE FROM HERCULES, INC.,
JACKSONVILLE, ARKANSAS, 1970
Parameter
Temperature, °C
PH
Total alkalinity to
pH 4.2, mg/liter
Biochemical oxygen
demand, mg/liter
Chemical oxygen
demand, mg/liter
Total solids,
mg/liter
Suspended solids,
mg/liter
Settleable solids,
mg/liter
Chloride, mg/liter
Chlorophenols ,
mg/liter
Phenoxy acids ,
mg/liter
Volume, liters
Dissolved oxygen,
mg/liter
Weather
Sampling date
January 25
12
7.5
560
515
700
6,960
160
6
3,000
68
167
37,600
6
Clear
March 3
18
7.6
2,250
1,680
2,500
40,100
360
16
19,350
118
183
360,600
5.8
Heavy rain
April 21
21
7.4
3,960
3,840
6,200
76,320
380
40
37,350
125
241
114,500
3.0
Clear
May 28
28.5
7.4
4,510
6,315
8,315
104,860
580
40
52,150
112
235
78,100
a
Clear
August 27
24
7.0
305
400
1,290
11,000
Nil
1.3
4,950
74
199
5,400
a
Clear
No data.
Source: Adapted from Sidwell,
1971, Table XXI, p. 51.
TABLE B.7.3. RELATIVE CHLOROPHENOL CONTENT OF INDUSTRIAL WASTE FROM
HERCULES, INC., JACKSONVILLE, ARKANSAS, 1970
Compound
Phenol
2-Chlorophenol
4-Chlorophenol
2 , 4-Dichlorophenol
2 , 5-Dichlorophenol
2 , 6-Dichlorophenol
2,4, 5-Tr ichlorophenol
2,4, 6-Tr ichlorophenol
Chlorophenol content (% of
January 25
3.4
2.9
2.5
73.6
Trace
9.9
4.7
2.8
March 3
6.2
6.1
12.1
17.9
6.2
41.7
Trace
9.9
April 21
1.7
Trace
18.3
20.0
1.7
38.8
Trace
19.5
total phenols)
May 28
24.8
Trace
20.0
11.4
Trace
30.5
Trace
13.3
August 27
Trace
Trace
2.8
89.0
1.8
3.0
Trace
3.4
Source: Adapted from Sidwell, 1971, Table XXI-A, p. 51.
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127
to the levels of chlorophenols in water has yet to be documented. There
is no information on the distribution of 2-chlorophenol and 2,4-dichloro-
phenol in water, aquatic organisms, and sediments.
B.7.2.3 Distribution in Soil
The primary source of soil contamination by chlorophenols is probably
through the application of 2,4-D and its derivatives on croplands. In
1971, U.S. farmers applied almost 16,000,000 kg of 2,4-D, representing
15% of all organic herbicide usage (U.S. Department of Agriculture, 1974).
Although usage declined slightly compared with 1966 usage, there most
likely has been substantial use over the past five years. Commercial
formulations of 2,4-D reportedly contain 2,4-dichlorophenol as an impurity;
the amount ranges from 70 to 4500 mg/kg (Aly and Faust, 1965). In addi-
tion, 2,4-D is degraded rapidly by soil microorganisms and produces 2,4-
dichlorophenol as an early metabolite. Therefore, the 2,4-dichlorophenol
generated from herbicide applications has the potential to accumulate,
depending on environmental conditions, and to move, depending on its
interactions with the soil.
The major factors affecting the distribution of 2,4-dichlorophenol
in soils are degradation and sorption. If the chemical persists due to
environmental conditions unfavorable for microbial growth, then it has
more time to interact with the soil. Movement of 2,4-dichlorophenol in
soil has apparently not been investigated. Evidence shows that the com-
pound is weakly sorbed, making it susceptible to leaching through the
soil profile. However, at normal rates of application the herbicide and
its metabolites are degraded readily so that downward movement is
minimized.
Groundwater contamination with 2,4-D and 2,4-dichlorophenol is evi-
dent when large doses are released into the environment. In 1945, a
company began to manufacture 2,4-D in California, emptying wastes con-
taining 2,4-D and 2,4-dichlorophenol into the local sewage system.
Within 17 days, phenolic tastes and odors were reported downstream in
shallow wells, and they persisted for three years (Swenson, 1962). At
the Rocky Mountain Arsenal in Colorado, 2,4-D was manufactured and wastes
were discharged into lagoons from 1943 to 1957. Groundwater contamination
was first reported in 1951 when crops were damaged by irrigation well
water (Walker, 1961). It took seven to eight years for the contaminant
to migrate 5.6 km and to affect an area of 16.8 km2.
B.7.3 ENVIRONMENTAL FATE
B.7.3.1 Mobility and Persistence in Air
The forms in which 2-chlorophenol and 2,4-dichlorophenol are trans-
ported in the atmosphere are unknown. Although these compounds are
capable of being dispersed to the atmosphere through volatilization, no
investigations have been made on their presence, movement, fate, and
persistence. Possibly, photodecomposition is an important mechanism of
dissipation.
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128
B.7.3.2 Mobility and Persistence in Aquatic Environments
Chlorophenols may be present in the aquatic environment as the
dissolved form, associated with suspended matter or bottom sediments,
and absorbed in biological tissues. Hydrological factors such as pattern
of currents and mixing and decay and migration of organisms affect the
movement of these chemicals. However, no data have been reported to
support this premise.
A few studies indicate that the dissipation of 2-chlorophenol in
water is microbiologically mediated. Ettinger and Ruchhoft (1950) inves-
tigated the persistence of monochlorophenols in polluted river water and
diluted sewage at 20°C. Low concentrations (1 mg/liter) of 2-chloro-
phenol added to a usual dilution of domestic sewage were not removed
during periods of 20 to 30 days, presumably due to the absence of micro-
organisms capable of attacking the chemical. When a similar concentra-
tion was added to polluted river waters, the compound dissipated in 15
to 23 days (Table B.7.4). Addition of a seed consisting of water from a
previous persistence experiment significantly increased the removal of
2-chlorophenol. Apparently, the seed introduced some organisms already
adapted to the chemical. This study also indicates that the removal of
monochlorophenols requires the presence of a specialized microflora.
TABLE B.7.4. PERSISTENCE OF MONOCHLOROPHENOLS ADDED TO SEVERAL SURFACE
WATERS AT 20°C
Residual monochlorophenols (yg/liter)
stored
(days)
0
6
13
15
23
36
Great Miami
2-Chlorophenol
980
810
790
760
710
0
River water
4-Chlorophenol
1000
980
80
0
0
0
Little Miami
2-Chlorophenol
890
870
480
0
0
0
River water
4-Chlorophenol
1000
1000
0
0
0
0
Source: Adapted from Ettinger and Ruchhoft, 1950, Table 2, p. 3a.
Baird et al. (1974) employed Warburg respiratory techniques to dem-
onstrate that biodegradation of 2-chlorophenol at a concentration of
1 mg/liter in activated sludge was complete within 3 hr. Increasing the
concentration to 100 mg/liter reduced considerably the rate of respira-
tion so that only 20% was degraded in 6 hr. In a sludge not acclimated
with high levels of 2-chlorophenol, certain amounts of the compound may
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129
be degraded initially, and oxidative intermediates that appear subse-
quently could be toxic to the microbial population. This study indicates
that 2-chlorophenol may persist longer if waste containing high levels
of the chemical is discharged to an unacclimated body of water due to
direct or indirect toxic effects.
The persistence of 2,4-dichlorophenol in the aquatic environment
appears to be short. Aly and Faust (1964) studied the disappearance of
2,4-dichlorophenol at concentrations of 100, 500, and 1000 yg/liter in
natural lake waters buffered at pH 7.0 and continually aerated. Complete
disappearance of 2,4-dichlorophenol occurred within 9 days from the 100
yg/liter treatment, and 97.5% dissipated from the 500 and 1000 ug/liter
treatments in 30 days (Table B.7.5). At all rates of application, 50%
of the chlorophenol was decomposed in a matter of 6 days. To simulate
the effect of excessive amounts of decaying organic matter on biological
decomposition, ethanolic solutions of 2,4-dichlorophenol were added to
unbuffered, unaerated lake water. 2,4-Dichlorophenol persisted for more
than 43 days. Anaerobic conditions, as indicated by the presence of
TABLE B.7.5. PERSISTENCE OF 2,4-DICHLOROPHENOL IN LAKE WATER
AFTER ADDITIONS OF 100, 500, OR 1000 yg/liter 2,4-DICHLOROPHENOL
Time
(days)
100 yg/liter
Oxidation
500 yg/liter
Oxidation
1000 yg/liter
Oxidation
Aerated and buffered
0 7.4 0.0 7.4 0.0 7.4 0.0
2 7.3 36.0 7.6 22.0 7.6 24.0
9 7.3 100.0 7.5 66.0 7.4 54.0
16 6.9 100.0 7.1 81.6 7.2 83.5
23 a a 7.5 93.6 7.5 92.2
30 a a 7.3 97.5 7.3 97.5
Unaerated and unbuffered
0
3
7
14
17
24
43
7.3
6.2
6.1
a
7.9
a
a
0.0
20.0
30.0
a
60.0
60.0
80.0
7.3
5.1
6.1
a
6.5
a
a
0.0
22.0
24.0
a
49.4
61.6
61.6
7.3
4.1
6.0
6.1
6.3
a
a
0.0
22.0
23.0
38.0
44.0
46.0
49.0
No data.
Source: Adapted from Aly and Faust, 1964, Table VII, p. 546.
Reprinted by permission of the publisher.
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130
hydrogen sulfide, prevailed in the system. This limited information
suggests the importance of biological degradation in 2,4-dichlorophenol
dissipation. Although the compound appears to be easily degraded, limno-
logical factors such as oxygen depletion could inhibit the process and
thereby extend its persistence. Similar observations were noted for
2,4-D. The effects of anaerobic and aerobic conditions on 2,4-D, as
modified by temperature, were determined in a sediment-free impoundment
model with controlled chemical and thermal stratification (Demarco,
Symons, and Robeck, 1967).
Sidwell (1971) studied the persistence of 2,4-dichlorophenol in
aeration lagoon effluent. The initial concentrations of 2,4-dichloro-
phenol and 2,4-D were 64 and 174 mg/liter respectively. Constant aera-
tion was introduced to the acid-phenol effluent, which was adjusted to
pH 7.0 and maintained at a temperature of 20°C to 21°C. 2,4-Dichloro-
phenol disappeared within five days — more rapidly than 2,4-D (Figure
B.7.1). This removal rate indicates that sufficient nutrients and a
large microbial population capable of metabolizing the chlorophenol were
present in the effluent.
ORNL-DWG 78-10499
200
DISTILLED WATER
CONTROL
2,4 -D CONCENTRATION
2,4-DICHLOROPHENOL
CONCENTRATION
6 8
TIME (days)
Figure B.7.1. Removal of 2,4-dichlorophenol and 2,4-D from solution
in aeration basin effluent by continuous aeration. Source: Adapted from
Sidwell, 1971, Figure 5, p. 67.
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131
Conditions affecting the biodegradability of chlorophenols were
investigated by Ingols, Gaffney, and Stevenson (1966) with acclimated,
activated sludge. The effects of pH, temperature, and concentration are
given in Tables B.7.6 and B.7.7. Optimum temperature for degradation of
2-chlorophenol appeared to be between 25°C and 27°C, and optimum pH
ranged from 6.5 to 8.0. Degradation was uninhibited by up to 100 mg/liter
of 2,4-dichlorophenol. Complete ring cleavage of 2-chlorophenol and
2,4-dichlorophenol occurred in three and five days respectively (Table
A.7.1).
B.7.3.3 Mobility and Persistence in Soil
The most important interaction of chlorophenols in soils is sorption.
The extent of sorption determines whether the compounds are carried in
association with eroded soils during overland flow or are leached through
the soil profile during infiltration. Soil factors affecting sorption
are pH, moisture, and content of clay and organic matter.
Sorption of 2-chlorophenol by soils has not been studied, but 2,4-
dichlorophenol sorption by clay minerals has been reported. Aly and
Faust (1964) found that 2,4-dichlorophenol and 2,4-D compounds were
sorbed by bentonite, illite, and kaolinite, but the magnitude was small
as shown by the high amount of clays required to remove significant
amounts of each compound from an aqueous suspension (Table B.7.8). 2,4-
Dichlorophenol was sorbed by illite and bentonite to a greater extent
than was the sodium salt of 2,4-D. Extent of sorption was directly pro-
portional to the specific surface area of the clay minerals. Thus, ben-
tonite, an expanding-lattice clay mineral, had the highest sorption
followed by the nonexpanding-lattice clays, illite and kaolinite. Because
2,4-dichlorophenol is a weak acid, it will ionize to varying degrees de-
pending on the pH of the system. Negative sorption of organic anions —
formed as a result of ionization of acidic pesticides — by clay colloids
occurred at pH values in excess of 7, bat positive sorption of molecular
species occurred in strongly acidic systems (Weber, 1972). Although
sorption of molecular species through physical forces was probably the
primary mechanism, sorption of anionic species may also occur because
kaolinite, illite, and hydrous metallic oxides possess anion-exchange
properties.
Organic matter is a soil component largely responsible for the sorp-
tion of many organic compounds. Information on 2,4-dichlorophenol sorp-
tion by organic matter is not available; therefore, its sorption by this
component can only be inferred from studies on acidic pesticides such as
2,4-D. Acidic pesticides were sorbed to organic soil colloids which
were controlled by the pH of the system; sorption was greater under
acidic conditions where the pesticides were sorbed in the molecular form
(Hamaker, Goring, and Youngson, 1966). The amounts of acidic pesticides
sorbed were much lower than amounts of pesticide groups such as the s-
triazines, organochlorine, and bipyridyl compounds (Weber, 1972). Sorp-
tion probably occurred through hydrogen bonding or physical sorption of
molecular species to the organic colloidal surfaces. Sorbed species were
easily desorbed by water, indicating that the sorption bond strength is
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132
TABLE B.7.6. EFFECT OF TEMPERATURE AND pH
ON THE DEGRADATION OF 2-CHLOROPHENOLa
Degradation (%)
pn
6.5
6.8
7.3
7.9
8.4
9.3
20°C
33
b
27
20
b
b
25°C
b
74
b
b
22
3
27°C
88
b
89
91
b
b
30°C
b
57
b
b
6
0
200 mg/liter concentration; acclimated
activated sludge aerated for one day.
^No data.
Source: Adapted from Ingols, Gaffney,
and Stevenson, Table 1, p. 631. Reprinted
by permission of the publisher.
TABLE B.7.7. EFFECT OF CONCENTRATION ON THE DEGRADATION OF 2,4-DICHLOROPHENOL
„ , Concentration
C°mpOUnd (mg/liter)
2,4-Dichlorophenol, after two days
2,4,6-Trichlorophenol, after two days
Dichloroquinone, after four days
50
100
200
400
50
100
200
400
50
100
200
400
Ring
cleavage
80
75
40
55
100
100
60
0
100
100
100
20
Development
of chloride
ion
47
35
12
3
19
28
5
0
100
50
31
19
Acclimated activated sludge maintained at pH 7.0 and 26°C.
Source: Adapted from Ingols, Gaffney, and Stevenson, Table III, p. 631.
Reprinted by permission of the publisher.
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133
TABLE B.7.8. AMOUNT OF CLAYS REQUIRED TO REDUCE THE CONCENTRATIONS OF
2,4-DICHLOROPHENOL AND 2,4-D COMPOUNDS TO 2.0 mg/liter
Initial
concentration
(mg/liter)
Compound
Amount of clay (g)
Kaolinite
Illite
Bentonite
3
4
5
6
2 , 4-Dichlorophenol
2,4-D sodium salt
2,4-D isopropyl ester
2,4-D butyl ester
2,4-D isooctyl ester
2 , 4-Dichlorophenol
2,4-D sodium salt
2,4-D isopropyl ester
2,4-D butyl ester
2,4-D isooctyl ester
2 , 4-Dichlorophenol
2,4-D sodium salt
2,4-D isopropyl ester
2,4-D butyl ester
2,4-D isooctyl ester
2 , 4-Dichlorophenol
2,4-D sodium salt
2,4-D isopropyl ester
2,4-D butyl ester
2,4-D isooctyl ester
96.1
26.3
37.6
42.7
44.6
192.2
52.6
75.2
85.5
89.2
288.3
78.9
113.8
128.2
133.9
384.6
105.3
150.4
170.9
178.5
19.2
35.0
11.8
13.3
14.2
38.5
69.9
23.6
26.7
28.3
57.7
104.9
35.4
40.0
42.5
76.9
129.9
47.2
53.3
56.6
16.4
40.0
6.9
8.8
10.3
32.8
80.0
13.8
17.5
20.6
49.2
120.0
20.7
25.3
30.9
65.6
160.0
27.6
35.1
41.2
Source: Adapted from Aly and Faust, 1964, Table II, p. 543.
Reprinted by permission of the publisher.
weak. It is highly probable that the sorption behavior of 2-chlorophenol
and 2,4-dichlorophenol is similar to that of 2,4-D. In natural soil sys-
tems, sorption may not be extensive, thereby favoring their downward
movement in soil with water.
The persistence of 2-chlorophenol in soils was studied by Walker
(1954) using the percolation technique. Solutions of 2-chlorophenol
(1.0 g) were allowed to percolate through 100 g of a Rothamsted soil
(light clay with a pH of 6.8), and the disappearance of the initial and
subsequent doses was measured. Two-thirds of the initial dose disappeared
in ten days. Disappearance of subsequent doses occurred approximately
twice as rapidly as that of the first dose, suggesting microbial partic-
ipation. Further evidence of microbial decomposition was indicated by
the more rapid disappearance of 2-chlorophenol in fresh soil than in
sterilized soil within seven days of percolation.
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134
Participation of soil microorganisms in the dissipation of 2-chloro-
phenol, 2-4-dichlorophenol, and other chlorophenols is also indicated by
the investigation of Alexander and Aleem (1961) using suspensions of two
silt loam soils. Microbial metabolism of the chemicals was evidenced by
more rapid disappearance of incremental additions of the compounds than
of initial enrichments. Also, inhibition of degradation occurred with
addition of sodium azide, a toxic agent. 2-Chlorophenol and 2,4-dichloro-
phenol disappeared rapidly in suspensions of Dunkirk and Mardin silt loams;
disappearance was faster for the latter soil (Table A.7.2). 2,4-Dichloro-
phenol was degraded faster than 2,4-D. Sharpee (1973) reported accumula-
tion of 2,4-dichlorophenol during the degradation of 2,4-D in soils, but
it did not persist as long as the herbicide.
Although 2-chlorophenol and 2,4-dichlorophenol appear to be short-
lived in soils, the data are inconclusive and factors affecting their
persistence need further study. However, there are indications that
microbial degradation is the major avenue of dissipation for these chemi-
cals in soils. Under field conditions, degradation of 2,4-dichlorophenol,
which is more likely to reach the soil system as a contaminant and deg-
radation product of 2,4-D, could be faster than degradation of the
herbicide. The role of microorganisms in the degradation of 2,4-D has
been conclusively demonstrated (Loos, 1975); under favorable conditions,
2,4-D disappears from soils in about 30 days (Kearney et al., 1969).
Warm, moist, well-aerated soils with ample organic matter promote the
proliferation of microorganisms known to metabolize 2,4-D.
B.7.3.4 Microbial Decomposition in Soils and Aquatic Environments
As discussed previously, microorganisms may play a major role in
the dissipation of chlorophenols in the environment. Therefore, these
chemicals could persist longer under conditions unfavorable for micro-
bial growth and activity. In this section, the microorganisms involved
and possible degradation pathways for 2-chlorophenol and 2,4-dichloro-
phenol are discussed.
Limited information indicates that 2-chlorophenol is biodegradable
(Walker, 1954; Baird et al., 1974). Several genera of bacteria isolated
from soils are capable of metabolizing 2-chlorophenol. Pseudomonas sp.,
Nooardia sp., Myeobaeterium coeliacwn, and Bacillus sp. can oxidize 2-
chlorophenol to 3-chlorocatechol (Spokes and Walker, 1974). The fate of
the catechol intermediate was elucidated by a study of the metabolism
of 2,4-D by Pseudomonas sp. (Evans et al., 1971). 2,4-Dichlorophenoxy-
acetic acid was used as the sole carbon source for Pseudomonas strains
isolated from soil. The herbicide was metabolized to 2,4-dichlorophenol,
2-chlorophenol, 3,5-dichlorocatechol, and ct-chloromuconate, which was
further metabolized to release Cl~ and unidentified metabolites. The
appearance in culture of 2-chlorophenol suggests that nonoxidative elimi-
nation of chlorine occurred from 2,4-dichlorophenol or possibly from
2,4-D itself. The accumulation of a-chloromuconate is probably a further
manifestation of this phenomenon; it is likely formed by the action of
the ring cleavage enzyme of 3-chlorocatechol, which, in turn, is derived
from either 2-chlorophenol or 3,5-dichlorocatechol. Figure B.7.2 outlines
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135
ORNL—DWG 78 — 10500
0-CH2-COOH
2- CHLOROPHENOXYACETIC
ACID
2-CHLOROPHENOL
Cl 3-CHLOROCATECHOL
3,5-DICHLOROCATECHOL I
COOH
0-CHLOROMUCONIC ACID
UNIDENTIFIED
METABOLITES
Figure B.7.2. Proposed pathway of 2-chlorophenol degradation by
Pseudomonas sp. Source: Adapted from Evans et al., 1971, Scheme 1,
p. 550. Reprinted by permission of the publisher.
a possible pathway of 2-chlorophenol metabolism in microorganisms which
involves orthohydroxylation of the ring followed by ring cleavage.
Further degradation products have not been identified.
Soil bacteria capable of detoxifying phenoxy herbicides, including
Arthrobaater sp. and Pseudomonas sp., are also active in 2,4-dichloro-
phenol decomposition. The potential clearly exists for bacterial enzymes
adapted to phenoxy herbicides to attack compounds structurally related to
the herbicides. Intact cells of Arttoobacter sp. are capable of convert-
ing 2,4-D and other phenoxyacetates to the corresponding Phenols (Loos
Bollag, and Alexander, 1967; Loos, Roberts, and Alexander 1967a, 1967b).
2,4-Dichlorophenol formed from 2,4-D is, in turn, oxidized by "^robial
cells. Bollag et al. (1968) and Bollag, Helling, and Alexander (1968)
studied the metabolism of 2,4-dichlorophenol by Artfoobaeter sp capable
of detoxifying phenoxyacetate. 2,4-Dichlorophenol was converted to 3,5-
dichlorocatechol through enzymatic orthohydroxylation (Figure B 7.3).
Oxygen and NADPH were required in the reaction. The catechol produced
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136
ORNL-DWG 78-10501
C' 3.5-DICHLOROCATECHOL Q-CHLORO-y-CARBOXY-
2 4-DICHLOROPHENOL
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137
Dioxin formation through microbial condensation of 2-chlorophenol
and 2,4-dichlorophenol is of interest because of the high toxicity of
dioxins. No evidence of this reaction was observed by Kearney, Woolson,
and Ellington (1972) in two soils incubated with 10 to 1000 mg/liter
2,4-dichlorophenol for 70 days. Microbial condensation reactions of
lower chlorophenols to form dioxins in the environment appear unlikely.
This information is important because biosynthetic production of dioxins
from chlorophenols or herbicide metabolites is impossible to regulate
under environmental conditions.
Although degradation studies have been performed in vitro, the
degradation mechanisms and products of 2-chlorophenol and 2,4-dichloro-
phenol may be the same in soils and aquatic environments. Apparently,
the same microorganisms are responsible for the metabolism of these
chemicals. Metabolite accumulation could possibly occur. Sharpee (1973)
found that when 2,4-D was added to a freshwater and sediment system, an
unknown compound(s) persisted long after the 2,4-D had disappeared.
Persistence and accumulation are expected in anaerobic environments.
B.7.3.5 Photodecomposition
Many organic compounds, including chlorophenols, undergo photo-
chemical decomposition when exposed to ultraviolet light. The prime
requirement for such reactions is the absorption of ultraviolet light
energy by the compounds. Photochemically induced degradation occurs at
surfaces of airborne particulates and water. Chlorophenols reach such
surfaces by various mechanisms and therefore are subject to exposure to
sunlight and are susceptible to photochemical degradation.
The photochemical reaction of 2,4-dichlorophenol is elucidated
partially from irradiation studies of 2,4-D. Aly and Faust (1964) demon-
strated the rapid decomposition of an aqueous solution of the 2,4-D
sodium salt and 2,4-dichlorophenol exposed to ultraviolet light. Losses
of 50% were detected within 50 min for 2,4-D and within 5 min for 2,4-
dichlorophenol at pH 7.0. Rates of photolysis were lowest at pH 4 and
reached a maximum at pH 9. 2,4-Dichlorophenol decomposed more rapidly
than 2,4-D at all pH values. Several studies have shown that 2,4-
dichlorophenol is the major photolytic product of 2,4-D compounds (Aly
and Faust, 1964; Crosby and Tutass, 1966; Boval and Smith, 1973; Zepp
et al., 1975) and nitrofen (Nakagawa and Crosby, 1974a, 19742?). Aly and
Faust (1964) noted an increase followed by a decrease in the amounts of
2,4-dichlorophenol produced from 2,4-D compounds with time, suggesting
further photolysis of the chemical. Crosby and Tutass (1966) irradiated
aqueous solutions of 2,4-D sodium salt with ultraviolet light at 254 nm
and identified the photolysis products (Figure B.7.4). The major reaction
was the cleavage of the ether bond to produce 2,4-dichlorophenol, which
was dehalogenated or hydroxylated under the influence of ultraviolet light
to form 4-chlorocatechol and 1,2,4-benzenetriol. The benzenetriol was
oxidized and polymerized rapidly to humic acids by a light-independent
process. Sunlight irradiation of 2,4-D in water or on filter paper
yielded photolytic products qualitatively similar to those formed under
ultraviolet irradiation. Photodecomposition of the herbicide nitrofen
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138
ORNL-DWG 78-10502
2,4-DICHLOROPHENOL
4-CHLOROCATECHOL
OCH2COOH
OH
Cl
4-CHLORO-
2-HYDROXYPHENOXYACETIC
ACID
HUMIC
ACID
OH
2-CHLORO-4-
HYDROXYPHENOXYACETIC
ACID
1,2,4-BENZENETRIOL
OCH2COOH
OH
Figure B.7.4. Photolysis pathway for 2,4-D. Source: Adapted from
Crosby and Tutass, 1966, Figure 3, p. 599. Reprinted by permission of
the publisher.
in aqueous suspensions under sunlight or simulated sunlight (ultraviolet
irradiation) also was characterized by rapid cleavage of the ether link-
age to give 2,4-dichlorophenol and 4-nitrophenol as the major products
(Nakagawa and Crosby, 1974a). The 2,4-dichlorophenol arising from nitrofen
appeared to follow the same photolytic pathway shown in the investigation
of Crosby and Tutass (1966).
The possibility of dioxin formation during photolysis of 2,4-dichloro-
phenol has been of concern. Plimmer and Klingebiel (1971) studied the prod-
ucts of riboflavin-sensitized photodecomposition of 2,4-dichlorophenol in
water irradiated at a wavelength of 280 nm. Major products identified were
dimeric compounds; no dioxins were detected. Therefore, it seems unlikely
that dioxins will be formed from 2,4-dichlorophenol in aquatic systems.
In natural systems, photochemical reactions are likely to occur
simultaneously with adsorption and microbial decomposition. For the
chlorophenols, microbial decomposition appears to be the dominant dis-
sipation mechanism. However, photodecomposition possibly contributes to
the dissipation of airborne chlorophenols.
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139
B.7.4 WASTE MANAGEMENT
Chlorophenols occur in natural waters and wastewaters through vari-
ous sources and/or reactions. They are present with other organic com-
pounds in concentrations ranging from low in natural waters to high in
wastewaters generated from the manufacture of chlorophenols and phenoxy-
alkanoic herbicides. In this section, treatment processes applicable to
wastewater containing 2-chlorophenol and 2,4-dichlorophenol are discussed
along with removal of these chemicals from drinking water.
B.7.4.1 Primary Treatment
Primary treatment consists essentially of settling solids after
screening off large materials. Settling may not remove 2-chlorophenol
and 2,4-dichlorophenol from water because, as indicated earlier, these
chemicals are sorbed poorly on particulate or suspended matter. Chemical
coagulation could be employed to improve the settling of solids from
wastewater. However, Aly and Faust (1965) reported the ineffectiveness
of flocculants such as aluminum sulfate and ferric sulfate in decreasing
the concentrations of 2,4-dichlorophenol and 2,4-D in water. Apparently,
2,4-D and 2,4-dichlorophenol stay either in solution or in discrete form,
depending on the pH of the wastewater, and are unaffected by coagulants
or sorbents. Chlorophenols are dissociated mainly in aqueous solutions
with pH values higher than 5 (Cserjesi, 1972).
B.7.4.2 Secondary Treatment
Secondary treatment involves the removal of organic matter from
wastewater by biological processes. Biological methods used in waste
treatment include trickling filters, activated sludge, and oxidation
ponds. These methods all work on the same principle: microorganisms
utilize the organic materials in the wastewater as a source of energy
and convert them to more simple, less toxic substances. Because 2-
chlorophenol and 2,4-dichlorophenol are easily biodegradable, secondary
treatment should provide excellent removal of these chemicals.
Mills (1959) removed "dichlorophenol" from a wastewater stream con-
taining 2,4-D by using a pilot plant designed as a combined trickling
filter and activated sludge system. The pilot plant unit was seeded
with activated sludge from a local sewage plant, and the waste stream
was diluted to 10% strength with water before treatment. The average
removal of "dichlorophenol" was 86%.
Sidwell (1971) used a combined aerated lagoon and stabilization
pond to study the biological treatment of wastes arising from the manu-
facture of phenoxyalkanoic herbicides, particularly 2,4-D and 2,4,5-
trichlorophenoxyacetic acid (2,4,5-T). The industrial waste, in addi-
tion to having a high biochemical oxygen demand and high concentrations
of solids and chlorides, contained a mixture of chlorophenols (Tables
B.7.2 and B.7.3). During the first four months of this study of the
joint treatment of domestic sewage and industrial waste, a period when
industrial activity was minimal, the average reduction of chlorophenols
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140
across the aeration lagoon and stabilization pond was 92%. During a
subsequent period of industrial plant operation, removal of chlorophenols
by the aerated lagoon alone ranged from 55% to 89%, and the overall re-
moval of chlorophenols by the lagoon and stabilization pond ranged from
87% to 94%. Removal of chlorophenoxy acids was lower, ranging from 30%
to 70% in the lagoon and 44% to 80% in the lagoon and stabilization pond.
Most of the chlorophenols are likely to be decomposed in the aeration
lagoon. In vitro experiments with individual chlorophenols, including
2,4-dichlorophenol and the related chlorophenoxy acids diluted with
aeration effluent, indicated that these compounds are degraded rapidly
when a sufficient microbial population has been developed. Obviously,
the bacterial population capable of degrading these compounds and the
nutrients required by these populations are present in the aeration
lagoon effluent.
B.7.4.3 Soil Disposal
As previously discussed (Section B.7.3.4), 2-chlorophenol and 2,4-
dichlorophenol are biodegradable by soil organisms. Hence, soil disposal
could be employed as a biological method of treating wastes containing
chlorophenols. On this basis, Montgomery et al. (1971) investigated the
treatment of pesticide wastes resulting from the manufacture of 2,4-D by
land application. The waste concentrate consisted primarily of unreacted
2,4-dichlorophenol, unrecovered 2,4-D, and considerable amounts of sodium
hydroxide. The waste material was diluted and applied to approximately
3- by 3-m plots at the rate of 900 kg 2,4-dichlorophenol and 300 kg 2,4-D.
The plots were watered immediately to insure that the waste material pene-
trated the soil and was available to microorganisms. Analyses of soil
collected at different depths showed significant reduction of 2,4-dichloro-
phenol and 2,4-D in the first month following application. After this
period, the concentrations of 2,4-dichlorophenol and 2,4-D generally
declined until about the eleventh month when the last samples were taken.
Microbial populations were reduced significantly a short time after
application, presumably due to the adverse effect of high concentrations
of the chemicals. However, within four to six months, a gradual return
to normal populations was observed. Proper maintenance of moisture and
temperature accelerated the microbial degradation. Although soil disposal
is a promising means of chemical waste treatment, high land values may
limit its use.
B.7.4.4 Chemical Oxidation
Chlorination is practiced primarily for disinfecting drinking water
and effluents from primary and secondary treatment plants. It also is
employed for removal of chlorophenolic tastes and odors caused primarily
by monochlorophenols and dichlorophenols. During chlorination of water,
2-chlorophenol could be chlorinated to 2,4-dichlorophenol, which, in
turn, is chlorinated to 2,4,6-trichlorophenol by stepwise substitution in
the 4 and 6 positions of the aromatic ring (Burttschell et al., 1959;
Eisenhauer, 1964; Manufacturing Chemists Association, 1972). The maximum
rate of chlorination occurs between pH 7 and 9 (Lee and Morris, 1962).
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141
With excess chlorine, ring oxidation follows the formation of 2,4,6-
trichlorophenol and results in the production of oxidized products, in-
cluding carboxylic acids. The ultimate products do not have offensive
tastes or odors.
The use of potassium permanganate for control of tastes and odors
has been accepted in water treatment plants. The effective oxidation
of 2,4-dichlorophenol by potassium permanganate has been reported. Aly
and Faust (1965) found that the amount of 2,4-dichlorophenol oxidized
was directly proportional to the amount of the oxidant added. The
optimum pH range for the oxidation was 4.0 to 7.0.
B.7.4.5 Ion Exchange
Although sorption of 2,4-dichlorophenol on clay minerals has been
shown to be insignificant (Aly and Faust, 1964), 2,4-dichlorophenol can
be sorbed to a large extent by ion-exchange resins (Aly and Faust, 1965)
Aly and Faust (1965) evaluated the possibility of using ion exchangers
to remove 2,4-dichlorophenol from natural waters. In general, the
strongly basic anion-exchange resins sorbed more of the chemical than
did the cation exchangers. Sorption was not due to the ion-exchange
process because no chlorides were released. Perhaps other mechanisms
could have been responsible for sorption.
B.7.4.6 Activated Carbon Adsorption
Activated carbon has been used in concentrating low levels of
chlorophenols and other organic compounds in water (Eichelberger et al.,
1970). Its utility as a water treatment method has been explored. Aly
and Faust (1965) effectively sorbed 2,4-dichlorophenol from water employ-
ing activated carbon. For an initial concentration of 100 ug/liter,
5.9 yg/liter of carbon was needed to reduce the concentration of 2,4-
dichlorophenol to 2 yg/liter.
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142
SECTION B.7
REFERENCES
1. Alexander, M., and M.I.H. Aleem. 1961. Effect of Chemical Structure
on Microbial Decomposition of Aromatic Herbicides. J. Agric. Food
Chem. 9(1):44-47.
2. Aly, 0. M., and S. D. Faust. 1964. Studies on the Fate of 2,4-D
and Ester Derivatives in Natural Surface Waters. J. Agric. Food
Chem. 12(6):541-546.
3. Aly, 0. M., and S. D. Faust. 1965. Removal of 2,4-Dichlorophenoxy-
acetic Acid Derivatives from Natural Waters. J. Am. Water Works
Assoc. 57(2):221-230.
4. Baird, R. B., C. L. Kuo, J. S. Shapiro, and W. A. Yanko. 1974. The
Fate of Phenolics in Wastewater — Determination by Direct-Injection
GLC and Warburg Respirometry. Arch. Environ. Contain. Toxicol. 2(2):
165-178.
5. Bollag, J. M., G. G. Briggs, J. E. Dawson, and M. Alexander. 1968.
2,4-D Metabolism: Enzymatic Degradation of Chlorocatechols. J.
Agric. Food Chem. 16(5):829-833.
6. Bollag, J. M., C. S. Helling, and M. Alexander. 1968. 2,4-D Metab-
olism: Enzymatic Hydroxylation of Chlorinated Phenols. J. Agric.
Food Chem. 16(5):826-828.
7. Boval, B., and J. M. Smith. 1973. Photodecomposition of 2,4-Dichlo-
rophenoxyacetic Acid. Chem. Eng. Sci. 28:1661-1675.
8. Burttschell, R. H., A. A. Rosen, F. M. Middleton, and M. B. Ettinger.
1959. Chlorine Derivatives of Phenol Causing Taste and Odor. J.
Am. Water Works Assoc. 51:205-214.
9. Crosby, D. G., and H. 0. Tutass. 1966. Photodecomposition of 2,4-
Dichlorophenoxyacetic Acid. J. Agric. Food Chem. 14(6):596-599.
10. Cserjesi, A. J. 1972. Detoxification of Chlorinated Phenols. Int.
Biodeterior. Bull. 8(4):135-138.
11. Demarco, J., J. M. Symons, and G. G. Robeck. 1967. Behavior of
Synthetic Organics in Stratified Impoundments. J. Am. Water Works
Assoc. 59(8):965-976.
12. Dow Chemical Company. 1977. Personal Communication. Midland, Mich.
13. Duxbury, J. M., J. M. Tiedje, M. Alexander, and J. E. Dawson. 1970.
2,4-D Metabolism: Enzymatic Conversion of Chloromaleylacetic Acid
to Succinic Acid. J. Agric. Food Chem. 18(2):199-201.
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143
14. Eichelberger, J. W., R. C. Dressman, and J. E. Longbottom. 1970.
Separation of Phenolic Compounds from Carbon Chloroform Extract for
Individual Chromatographic Identification and Measurement. Environ.
Sci. Technol. 4(7) -.576-578.
15. Eisenhauer, H. R. 1964. Oxidation of Phenolic Wastes: Part I.
Oxidation with Hydrogen Peroxide and a Ferrous Salt Reagent. J.
Water Pollut. Control Fed. 36(9):1116-1128.
16. Ettinger, M. B., and C. C. Ruchhoft. 1950. Persistence of Mono-
chlorophenols in Polluted River Water and Sewage Dilutions. U.S.
Public Health Service, Environmental Health Center, Cincinnati,
Ohio. 11 pp.
17. Evans, W. C., B.S.W. Smith, H. N. Fernley, and J. I. Davies. 1971.
Bacterial Metabolism of 2,4-Dichlorophenoxyacetate. Biochem. J.
122(4):543-551.
18. Hamaker, J. W., C.A.I. Goring, and C. R. Youngson. 1966. Sorption
and Leaching of 4-Amino-3,4,6-trichloropicolinic Acid in Soils. Adv.
Chem. Ser. 60:23-37.
19. Hemmett, R. B., Jr. 1972. The Biodegradation Kinetics of Selected
Phenoxyacetic Acid Herbicides and Phenols by Aquatic Microorganisms
(abstract). Diss. Abstr. Int. B 32(12):7097.
20. Ingols, R. S., P. E. Gaffney, and P. C. Stevenson. 1966. Biological
Activity of Halophenols. J. Water Pollut. Control Fed. 38(4):629-635.
21. Kearney, P. C., E. A. Woolson, and C. P. Ellington, Jr. 1972. Per-
sistence and Metabolism of Chlorodioxins in Soils. Environ. Sci.
Technol. 6(12):1017-1019.
22. Kearney, P. C., E. A. Woolson, J. R. Plimmer, and A. R. Isensee.
1969. Decontamination of Pesticides in Soils. Residue Rev. 29:
137-149.
23. Lee, G. F., and J. C. Morris. 1962. Kinetics of Chlorination of
Phenol-Chlorophenolic Tastes and Odors. Int. J. Air Water Pollut.
6:419-431.
24. Loos, M. A. 1975. Phenoxyalkanoic Acids. In: Herbicides, 2nd ed.,
P. C. Kearney and D. D. Kaufman, eds. Marcel Dekker, New York.
pp. 1-128.
25. Loos, M. A., J. M. Bollag, and M. Alexander. 1967. Phenoxyacetate
Herbicide Detoxication by Bacterial Enzymes. J. Agric. Food Chem.
15(5):858-860.
26. Loos, M. A., R. N. Roberts, and M. Alexander. 1967a. Formation of
2,4-Dichlorophenol and 2,4-Dichloroanisole from 2,4-Dichlorophenoxy-
acetate by Arthrobacter sp. Can. J. Microbiol. 13(6):691-699.
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144
27. Loos, M. A., R. N. Roberts, and M. Alexander. 1967£>. Phenols as
Intermediates in the Decomposition of Phenoxyacetates by an Arthro-
bactev species. Can. J. Microbiol. 13(6):679-690.
28. Lyr, H. 1962. Detoxification of Heartwood Toxins and Chlorophenols
by Higher Fungi. Nature (London) 195:289-290.
29. Manufacturing Chemists Association. 1972. The Effect of Chlorina-
tion on Selected Organic Chemicals. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C.
103 pp.
30. Mills, R. E. 1959. Development of Design Criteria for Biological
Treatment of an Industrial Effluent Containing 2,4-D Waste Water.
Can. J. Chem. Eng. 37:117-183.
31. Montgomery, M. L., D. Klein, R. Goulding, and V. H. Freed. 1971.
Biological Degradation of Pesticide Wastes. In: Fate of Pesticides
in Environment, A. S. Tahari, ed. Gordon and Breach Science Pub-
lishers, New York. pp. 117-125.
32. Nachtigall, M. H., and R. G. Butler. 1974. Metabolism of Phenols
and Chlorophenols by Activated Sludge Microorganisms (abstract).
Abstr. Annu. Meet. Am. Soc. Microbiol. 1974:184.
33. Nakagawa, M., and D. G. Crosby. 1974a. Photodecomposition of Nitro-
fen. J. Agric. Food Chem. 22(5):849-853.
34. Nakagawa, M., and D. G. Crosby. 1974Z>. Photonucleophilic Reactions
of Nitrofen. J. Agric. Food Chem. 22(6):930-933.
35. Plimmer, J. R., and U. I. Klingebiel. 1971. Riboflavin Photosen-
sitized Oxidation of 2,4-Dichlorophenol: Assessment of Possible
Chlorinated Dioxin Formation. Science 174:407-408.
36. Sharpee, K. W. 1973. Microbial Degradation of Phenoxy Herbicides
in Culture, Soil, and Aquatic Ecosystems (abstract). Diss. Abstr.
Int. B 34(3):954.
37. Sidwell, A. E. 1971. Biological Treatment of Chlorophenolic Wastes:
The Demonstration of a Facility for the Biological Treatment of a
Complex Chlorophenolic Waste. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C.
177 pp.
38. Spokes, J. R., and N. Walker. 1974. Chlorophenol and Chlorobenzoic
Acid Co-metabolism by Different Genera of Soil Bacteria. Arch.
Microbiol. 96:125-134.
39. Swenson, H. A. 1962. The Montebello Incident. Proc. Soc. Water
Treatment Exam. 11:84-88.
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145
40. U.S. Department of Agriculture. 1974. Farmers' Use of Pesticides
in 1971: Quantities. Agricultural Economic Report No. 252. Wash-
ington, D.C. 56 pp.
41. U.S. Department of Agriculture. 1976. The Pesticide Review 1975.
Washington, D.C. 40 pp.
42. U.S. International Trade Commission. 1976. Synthetic Organic Chem-
icals: United States Production and Sales, 1974. Washington, D.C.
pp. 21-194.
43. Walker, N. 1954. Preliminary Observations on the Decomposition of
Chlorophenols in Soil. Plant Soil 5(2):194-204.
44. Walker, N. 1973. Metabolism of Chlorophenols by Rhodotorula glutinis.
Soil Biol. Biochem. 5:525-530.
45. Walker, T. R. 1961. Ground-water Contamination in the Rocky Moun-
tain Arsenal Area, Denver, Colorado. Geol. Soc. Am. Bull. 72:489-494.
46. Weber, J. B. 1972. Interaction of Organic Pesticides with Particu-
late Matter in Aquatic and Soil Systems. Adv. Chem. Ser. 111:55-120.
47. Zepp, R. G. , N. L. Wolfe, J. A. Gordon, and G. L. Baughman. 1975.
Dynamics of 2,4-D Esters in Surface Waters: Hydrolysis, Photolysis,
and Vaporization. Environ. Sci. Technol. 9(13):1144-1150.
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B.8 ENVIRONMENTAL INTERACTIONS AND THEIR CONSEQUENCES
B.8.1 ENVIRONMENTAL CYCLING OF 2-CHLOROPHENOL AND 2,4-DICHLOROPHENOL
The sources, distribution, and fate of the monochlorophenols and
dichlorophenols in soils, aquatic environments, and the atmosphere are
discussed in Section B.7. A possible cycling of these chemicals in the
environment, indicating the likely sources of contamination, interactions,
and sinks, is depicted in Figure A.8.1. Caution should be used in the
interpretation of this cycle because only scanty data are available,
which makes it difficult to establish any pattern of distribution and
flow of the chemicals into various components of the environment.
Soil and aquatic systems could be contaminated through direct usage
of the chemicals or closely related compounds, discharge of industrial
wastes and sewage, and chlorination of water containing phenols. Although
no documentation is available on the relative contribution from each
source, contamination likely occurs mainly from application of 2,4-
dichlorophenoxyacetic acid (2,4-D), which contains 2,4-dichlorophenol
as a contaminant or degradation product or from discharge of chloro-
phenolic wastes generated from chemical plants manufacturing phenoxy-
alkanoic herbicides. The monochlorophenols and dichlorophenols are quite
volatile and, when introduced into the environment, are susceptible to
volatilization. Data on their presence in the atmosphere and their sub-
sequent redeposition during precipitation and fallout are nonexistent.
Like many other organic compounds, 2-chlorophenol and 2,4-dichloro-
phenol undergo physicochemical and biological interactions with various
components of the environment. These chemicals can be sorbed by soils,
sediments, and airborne particulate materials. Sorption plays a major
role in the downward and overland movement of contaminants from soil
surfaces. Those compounds that are tightly bound tend to associate with
the eroded soil during runoff, and weakly bound compounds may move with
the water phase during infiltration. Limited evidence indicates that
sorption of 2,4-dichlorophenol by clay minerals is insignificant (Aly
and Faust, 1965) so that the compound could move through the soil profile.
Thus, minimal losses are likely to be associated with erosion from agri-
cultural lands. The rates of chemical and biological transformations of
chlorophenols determine their persistence and subsequent degree of move-
ment in a particular segment of the environment. Chemical oxidation
occurs during treatment of wastewater (Section B.7.4.4); photodecomposi-
tion is possible when the chemicals are present on surfaces of water,
soil, and airborne particulates exposed to sunlight (Section B.7.3.5).
Although data. are. limited and fragmentary, 2-chlorophenol and 2,4-dichloro-
phenol are assimilated by soil and aquatic microorganisms (Section B.7.3),
absorbed by plants (Section B.4), and absorbed and/or ingested by mam-
mals (Sections B.5 and B.6). Microbial degradation appears to be the
principal mechanism of removal and the principal sink. The degree of
metabolism and mode of distribution of absorbed or ingested monochloro-
phenols and dichlorophenols in plants, wildlife, and mammals can influ-
ence bioaccumulation. Bioaccumulated chlorophenols, if they persist,
146
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147
can be returned either to the soil and water systems during decay and
excretion or can be consumed by higher organisms, including humans,
through the food chain.
B.8.2 2-CHLOROPHENOL AND 2,4-DICHLOROPHENOL
Available data indicate that contamination of food with 2-chloro-
phenol and 2,4-dichlorophenol is minimal; thus, transfer to humans
through the food chain appears to be remote. Although 2-chlorophenol
and 2,4-dichlorophenol are not used directly in agricultural production,
they may find their way into crops through an indirect means — the metab-
olism of plant-assimilated 2,4-D. A few reports indicated that 2,4-
dichlorophenol was present in potato tubers and rice plants treated with
2,4-D (Bristol et al., 1974; Sokolov et al., 1974). In stored potato
tubers, low levels of 2,4-dichlorophenol were detected (Bristol et al.,
1974). Large quantities of 2,4-dichlorophenol were found in rice plants;
however, rice grains contained no residue of the compound at maturity
(Sokolov et al., 1974). Isensee and Jones (1971) demonstrated the ab-
sorption of 2,4-dichlorophenol by soybeans and oats from soil. Negligi-
ble amounts of 2,4-dichlorophenol were detected in oat grains and soybean
seeds at maturity, indicating that the chemical was not accumulated.
Domestic animals, including poultry, may ingest feeds containing
pesticides or drink water contaminated directly with 2-chlorophenol and
2,4-dichlorophenol. Some studies showed the appearance and distribution
of 2,4-dichlorophenol in tissues of animals fed with 2,4-D and nemacide.
Muscle and fat tissues of sheep and cattle which consumed feed contain-
ing high concentrations of 2,4-D (300 to 2000 mg/kg) showed no detect-
able 2,4-dichlorophenol, but parts-per-million levels of the metabolite
were evident in the liver and kidney (Clark et al., 1975). Sherman,
Beck, and Herrick (1972) found no detectable residues of 2,4-dichloro-
phenol in fat or in breast muscle of laying hens administered feeds
containing 100 to 800 mg/kg nemacide. The liver and egg yolk contained
appreciable quantities of 2,4-dichlorophenol. These limited data indi-
cate that although 2,4-dichlorophenol tends to accumulate in liver and
kidney, it is not found in meats even at extremely high dosages of the
pesticides. Furthermore, Bjerke et al. (1972) reported no contamination
of milk and cream from cows dosed with feeds containing 100 to 1000 mg/kg
2,4-D.
Apparently direct exposure of humans to these chemicals during
manufacture constitutes the major hazard. Widespread distribution and
accumulation of 2-chlorophenol and 2,4-dichlorophenol in the environment
is unlikely because these compounds tend to degrade quite easily in soil
and aquatic systems. However, data are not conclusive; more definitive
investigations are needed to assess judiciously the environmental hazards
associated with the use of 2-chlorophenol and 2,4-dichlorophenol. For
example, accumulation in fish and other aquatic organisms exposed to
waters contaminated with the chemicals as a result of discharge of chlo-
rinated effluents from sewage and industrial waste treatments has not
been investigated.
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148
SECTION B.8
REFERENCES
1. Aly, 0. M. , and S. D. Faust. 1965. Removal of 2,4-Dichlorophenoxy-
acetic Acid Derivatives from Natural Waters. J. Am. Water Works
Assoc. 57(2):221-230.
2. Bjerke, E. L., J. L. Herman, P. W. Miller, and J. H. Wetters. 1972.
Residue Study of Phenoxy Herbicides in Milk and Cream. J. Agric.
Food Chem. 20(5):963-967.
3. Bristol, D., L. Cook, M. Koterba, and D. C. Nelson. 1974. Deter-
mination of Trace Residues of 2,4-D and 2,4-Dichlorophenol in Potato
Tubers. Abstr. Pap. Am. Chem. Soc. 1974:44.
4. Clark, D. E., J. S. Palmer, R. D. Radeleff, H. R. Crookshank, and
F. M. Farr. 1975. Residues of Chlorophenoxy Acid Herbicides and
Their Phenolic Metabolites in Tissues of Sheep and Cattle. J.
Agric. Food Chem. 23(3):573-578.
5. Isensee, A. R., and G. E. Jones. 1971. Absorption and Transloca-
tion of Root and Foliage Applied 2,4-Dichlorophenol, 2,7-Dichloro-
dibenzo-p-dioxin, and 2,3,7,8-Tetrachlorodibenzo-p-dioxin. J.
Agric. Food Chem. 19(6):1210-1214.
6. Sherman, M., J. Beck, and R. B. Herrick. 1972. Chronic Toxicity
and Residues from Feeding Nemacide [0-(2,4-Dichlorophenyl)0,0-
Diethyl Phosphorothioate] to Laying Hens. J. Agric. Food Chem.
20(3):617-624.
7. Sokolov, M. A., L. L. Knyr, B. P. Strekozov, V. D. Agarkov, A. P.
Chubenko, and B. A. Kryzkho. 1974. Behavior of Some Herbicides
during Rice Irrigation. Agrokhimiya 3:95-106.
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PART C
2,4,5-TRICHLOROPHENOL, 2,4,6-TRICHLOROPHENOL, AND TETRACHLOROPHENOLS
149
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C. 1 SUMMARY
C.I.I DISCUSSION OF FINDINGS
Only three trichlorophenol and tetrachlorophenol isomers have com-
mercial importance. 2,4,6-Trichlorophenol is used as a bactericide and
fungicide for preserving wood, leather, and glue and for treating mildew
on textiles. 2,4,5-Trichlorophenol and its sodium salts have been used
directly as germicides and as primary compounds in the synthesis of a
number of pesticides, including the herbicide 2,4,5-trichlorophenoxy-
acetic acid (2,4,5-T) and its derivatives. Most of the 2,4,5-trichloro-
phenol produced in the United States is used as an intermediate for the
synthesis of these pesticides. 2,3,4,6-Tetrachlorophenol, the only
tetrachlorophenol isomer of commercial importance, is used as a germicide
for the preservation of wood, latex, and leather and as an insecticide.
The three compounds have many similar physical and chemical prop-
erties. Each is a solid at room temperature and has very low solubility
in water but is readily soluble in a number of organic solvents. Each
compound is volatile with steam and to some extent from aqueous solution.
Chemical reactions of these compounds which may occur in the environment
are largely unknown.
A number of analytical techniques have been used to identify and
quantify trichlorophenols and tetrachlorophenols in soil, water, and
biological tissue samples. Gas-liquid chromatography, employing either
electron-capture or flame-ionization detectors, is the most widely used
technique for separating, identifying, and quantifying chlorophenols.
Because gas-liquid chromatography is sensitive to nanogram levels of
these compounds, it is adaptable for the quantification of trace amounts.
Colorimetric methods, although simple and rapid, lack specificity and
thus are only useful for semiquantitative determinations. Other less
sensitive methods of detection — including thin-layer chromatography,
infrared and ultraviolet spectrophotometry, and mass spectrometry —
are useful only when large concentrations of the compounds are present.
The mechanism of toxicity of higher chlorophenols to microorganisms
is not completely understood. It is believed that they affect the cell
membrane, with subsequent leakage of cell constituents, and perhaps
inactivate specific enzyme systems. Because they have low water solu-
bility and high lipid solubility, their gross effect on bacteria and
fungi is likely due to association with cellular lipids and subsequent
alteration of cell permeability. Exposure of bacteria to 2,4-6-tri-
chlorophenol causes leakage of certain cell constituents through the
cell membrane; 2,4,6-trichlorophenol also inhibits the enzyme catalase.
In addition, higher chlorophenols, particularly tetrachlorophenols, can
inhibit oxidative phosphorylation. The contributions of these mech-
anisms to the toxicity of higher chlorophenols to microorganisms is
unknown.
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All chlorophenols possess some bactericidal properties which gener-
ally increase with the degree of chlorine substitution up to the tri-
chlorophenol derivatives. The tetrachlorophenol isomers are considerably
less toxic to bacteria than the trichlorophenol isomers; however, tetra-
chlorophenols possess enhanced fungicidal activity. The pH of the media
has a profound effect on the bactericidal efficiency. For example, 2,4,6-
trichlorophenol is most effective in inhibiting growth of bacteria in
acidic systems, indicating that the undissociated compound is more genni-
cidal than the dissociated form.
Many fungi are susceptible to the toxic effects of 2,4,5- and 2,4,6-
trichlorophenol and 2,3,4,6-tetrachlorophenol. A pH-dependent effect on
toxicity, similar to that with bacteria, exists. The unionized form is
apparently more toxic to fungi than the ionized form. The pH effect is
important not only in assessing the degree of toxicity of these compounds
to various fungi, but also in determining the effectiveness of the com-
pounds as germicides.
Both 2,4,5- and 2,4,6-trichlorophenol are toxic to algae. The mech-
anism of this toxicity is not known, but both compounds pose a serious
hazard to algae in waste stabilization ponds. Care must be taken that
they are not dumped or allowed to seep into such waste treatment facilities.
No information on the algicidal properties of tetrachlorophenols is availa-
ble. However, it is expected that they pose a similar threat to healthy
algae growth.
Very little information on biological aspects of trichlorophenols
and tetrachlorophenols in vascular plants is available. 2,4,5-Trichloro-
phenol, 2,4,6-trichlorophenol, and 2,3,4,6-tetrachlorophenol are toxic
to the aquatic plant Lernna minor. 2,3,4,6-Tetrachlorophenol is three
times more toxic than 2,4,5-trichlorophenol, which is, in turn, approxi-
mately twice as toxic as 2,4,6-trichlorophenol. 2,3,4,6-Tetrachloro-
phenol and tetrachlorophenol conjugates have been detected in lettuce
plants grown in nutrient solutions containing lindane (y-1,2,3,4,5,6-
hexachlorocyclohexane). The nature of the conjugates and their role in
the biodegradation of 2,3,4,6-tetrachlorophenol are unknown.
Foliar application of 2,3,5-trichlorophenol increases the percent-
age of mitotic abnormalities in V-io-ia fdba plants. No effect on yield
has been noted, and the biological significance of the increased mitotic
abnormality rate is not known. 2,4,6-Trichlorophenol and tetrachloro-
phenols were not tested in this system.
No documented toxic effects of trichlorophenols and tetrachloro-
phenols on domestic animals and wildlife were found. No effect was noted
in cattle fed 2,4,5-trichlorophenol at levels up to 159 mg/kg body weight
for 78 days. The tetrachlorophenol isomers which can uncouple oxidative
phosphorylation may pose a hazard to domestic animals and wildlife if
the compound reaches the environment in large amounts. Toxicosis is
speculated to resemble the clinical picture of pentachlorophenol poison-
ing, but no data on potential effects are available.
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The higher chlorophenols may appear in animal tissues following
absorption of other organic compounds. Trichlorophenols and tetrachloro-
phenols have been detected in animal tissues following administration of
2,4,5-T, silvex, lindane, ronnel, and erbon. The potential for toxic
effects due to the presence of the pesticide metabolites are not known.
No toxic effects from the presence of chlorophenols produced from pesti-
cides in the animal have been found. Hazards to humans as consumers of
milk and meat have not been assessed. Demonstrable amounts of 2,4,5-
trichlorophenol were detected in the milk and cream of cows fed a diet
containing 300 to 1000 mg/kg of the herbicide 2,4,5-T.
The presence of musty taint in chickens and chicken eggs has been
ascribed to absorption of chloroanisoles by chickens from litter con-
taminated with chlorophenols. Fungi in the litter readily methylate
2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol to trichloroanisoles
and tetrachloroanisoles which are subsequently absorbed by chickens and
produce musty taint. Thus, the presence of these chlorophenols in
chicken houses should be scrupulously avoided. Consumption of tainted
chickens by humans is unlikely because of the lack of palatability.
Of the trichlorophenol and tetrachlorophenol isomers, only 2,4,6-
trichlorophenol has documented toxicity for aquatic organisms. Labora-
tory experiments indicate that 2,4,6-trichlorophenol is toxic to fish
and aquatic microfauna. Oxygen consumption and cell division in fertil-
ized sea urchin eggs are affected by concentrations of 2,4,6-trichloro-
phenol greater than 6.2 mg/liter. The tetrachlorophenol isomers are
probably as toxic to aquatic organisms as pentachlorophenol (Section
D.5.2.2). Pentachlorophenol is known to accumulate in aquatic organisms,
and tetrachlorophenols, in view of their similar lipid solubility and
other chemical and physical characteristics, may share this property.
Cutaneous contact with any chlorophenols should be avoided. The
trichlorophenol and tetrachlorophenol isomers are primary skin irritants.
Although there is no apparent danger from cutaneous absorption of 2,4,5-
or 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol dissolved in organic
solvents may be absorbed directly through the skin in acutely toxic
amounts. Residues of 2,4,5- and 2,4,6-trichlorophenol and several tetra-
chlorophenol isomers have been detected in the muscle, liver, and kidney
of experimental animals dosed with chemically similar organic compounds
(e.g., lindane and 2,4,5-T). The metabolic breakdown of higher chloro-
phenols in humans is speculative. 2,4,5-Trichlorophenol, 2,4,6-tri-
chlorophenol, and tetrachlorophenols are excreted primarily in the urine,
and conjugation to sulfuric and glucuronic acids may occur. Following a
one-week exposure to lindane, 2,4,5- and 2,4,6-trichlorophenol and
2,3,4,5- and 2,3,4,6-tetrachlorophenol were excreted in the urine for at
least one month; other studies indicated more rapid excretion.
Although documented cases of human toxicity due to trichlorophenol
or tetrachlorophenol exposure have not been reported, investigations
with experimental animals indicate that 2,4,5- and 2,4,6-trichlorophenol
and 2,3,4,6- and 2,3,5,6-tetrachlorophenol are lethal when administered
orally or parenterally in large amounts. Although mechanisms of toxicity
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are unclear, trichlorophenols and tetrachlorophenols possess the ability
to uncouple oxidative phosphorylation in higher animals; clinical symptoms
resemble those seen with acute pentachlorophenol poisoning. Additionally,
2,4,6-trichlorophenol has a convulsive action (similar to phenol) in ex-
perimental animals. A general property of uncouplers is the ability to
inhibit other enzyme systems in the cell, an effect likely to cause acute
poisoning and death in experimental animals. 2,4,5-Trichlorophenol and
2,4,6-trichlorophenol appear to be the least toxic of the higher chloro-
phenols. In experimental animals, LD50 values as high as 3 g/kg body
weight have been reported, and chronic feeding of 2,4,5-trichlorophenol
at levels of 1 g/kg results only in minor liver and kidney damage in rats.
The trichlorophenols are considered generally to be mildly toxic; tetra-
chlorophenols are considered to be more toxic, with an LD50 in experi-
mental animals ranging from 120 to 250 mg/kg. Tetrachlorophenols are
moderately toxic when ingested.
Long-term exposure to trichlorophenol formulations has caused chlor-
acne. The highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin may be pres-
ent as an impurity in technical grades of 2,4,5-trichlorophenol and is
capable of causing marked chloracne; therefore, this impurity may be
responsible for chloracne development among industrial workers exposed
to trichlorophenol formulations. Employees involved in the manufacture
of these compounds are exposed to a variety of compounds, and the symp-
toms cannot be clearly assigned to a specific chlorophenol.
2,4,5-Trichlorophenol promotes the appearance of benign and malig-
nant skin tumors in mice following an initiating dose of dimethylbenzan-
thracene, but it does not appear to be tumorigenic in the absence of an
initiator. No tumor-promoting activity was seen when 2,4,6-trichloro-
phenol alone was tested. No information on the possible tumorigenic
effects of tetrachlorophenols was found.
No effect was seen when 2,4,5-trichlorophenol was tested for embryo
toxicity or tetratogenicity in mice at daily dose rates as high as 9 mg/kg
body weight. Information on teratogenic effects of 2,4,6-trichlorophenol
or tetrachlorophenols was not found.
Although monitoring data on the presence of trichlorophenols and
tetrachlorophenols in air, water, or soil are not available, the rela-
tively high volatility of these compounds suggests that volatilization
is a major dispersal mechanism of the chemicals into the atmosphere. The
potential for large discharges exists in industrial plants where these
chlorophenols and the phenoxyalkanoic herbicides are manufactured.
Incineration could also generate volatile products through the burning
of containers or trash containing chlorophenols. Movement, persistence,
and fate of the compounds in the atmosphere are not understood; photo-
decomposition possibly contributes to their dissipation.
Contamination of aquatic environments with trichlorophenols and
tetrachlorophenols may arise from chlorination of phenol or lower chloro-
phenols in natural water or in primary or secondary effluents of waste
treatment plants or from direct addition of the chemicals from industrial
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sites to waterways [e.g., waste from the manufacture of 2,4-dichloro-
phenoxyacetic acid (2,4-D) and 2,4,5-T showed considerable amounts of
2,4,5- and 2,4,6-trichlorophenol]. Other possible sources are chemical
spills, washing of containers and drums in which chlorophenols and 2,4,5-T
(or similar herbicides) are stored, degradation products of silvex used
for aquatic weed control, and wet and dry atmospheric fallout. Addition-
ally, runoff from urban and agricultural watersheds could be an important
nonpoint source of chlorophenols in aquatic environments. Primary sources
include degradation products of 2,4,5-T, silvex, and related herbicides
which are widely applied in the environment. The exact contribution of
runoff to chlorophenol levels in water is not known.
Chlorophenols may be transported in aquatic environments in the
dissolved form, associated with suspended matter or bottom sediments,
or absorbed in biological tissues. Limited evidence indicates the rapid
microbiological degradation of 2,4,5- and 2,4,6-trichlorophenol in aquatic
environments and in activated sludge and aeration lagoon effluent. Thus,
trichlorophenols do not appear to pose a serious hazard in waste treatment
facilities normally exposed to them. Certain bacterial species capable of
metabolizing 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol were de-
rived from an activated sludge after cultures were acclimated to the
presence of chlorophenol. It is not known if species of bacteria capable
of metabolizing higher chlorophenols are widespread in nature. The danger
that these compounds may interfere with sewage treatment processes, par-
ticularly under shock-loading conditions, cannot be discounted. For
example, oxygen uptake in mixed microbial populations from a sewage treat-
ment plant was inhibited at 2,4,6-trichlorophenol concentrations of 50
and 100 mg/liter.
Factors such as oxygen depletion, pH, temperature, concentration of
the compound, and composition of the bacterial population affect the
degradation rates of trichlorophenols and tetrachlorophenols in aquatic
systems. No data are available on microbial decomposition of tetrachloro-
phenols in aquatic environments. Photodecomposition, which may contribute
to the dissipation of chlorophenols from aquatic systems, has been demon-
strated for closely related compounds such as 2,4,5-T. Although micro-
organisms probably play the crucial role in degradation, solar radiation
may contribute to degradation in water of sufficient clarity to allow
penetration of ultraviolet radiation.
Direct contamination of soils by trichlorophenols and tetrachloro-
phenols is probably minimal. For 2,4,5-trichlorophenol, the primary
source of contamination is from application of 2,4,5-T and silvex. Al-
though data are not available, atmospheric fallout or washout could also
contribute to soil contamination.
Preliminary data indicate that trichlorophenols and tetrachloro-
phenols are probably not tightly bound to soil particles. Under appro-
priate conditions, leaching through the soil profile is expected to occur,
but groundwater contamination is not documented. Persistence and degrada-
tion of trichlorophenol and tetrachlorophenol isomers in soil have not been
well studied. The participation of soil microorganisms in decomposition
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has been demonstrated, but it is not known if bacteria capable of metabo-
lizing higher chlorophenols are widely distributed in the environment.
Chlorophenol isomers with a chlorine atom in the meta position show marked
persistence. 2,4,6-Trichlorophenol is removed rapidly from soil, but
2,4,5-trichlorophenol and 2,3,4,5-tetrachlorophenol can persist for more
than 72 days. The reason for higher resistance to degradation by chloro-
phenols containing chlorine in the meta position is not known.
Of the trichlorophenol and tetrachlorophenol isomers likely to con-
taminate soil, 2,4,5-trichlorophenol poses the greatest hazard with re-
spect to accumulation and persistence. Persistence of any chemical of
course depends on the environmental conditions which affect microbial
growth and activity.
A number of fungal species isolated from poultry litter readily
degrade 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol to form the
corresponding anisoles. No information on possible degradation of 2,4,5-
trichlorophenol by fungi is available. The contribution of fungi to the
dissipation of trichlorophenols and tetrachlorophenols in the environment
has not been determined.
Chlorination of phenol, monochlorophenols, and dichlorophenols re-
portedly results in stepwise chlorination of the molecule up to the tri-
chlorophenol isomers. Further chlorination apparently results in ring
cleavage and the formation of a mixture of nonphenolic products. Ring
cleavage probably depends on optimum conditions for chlorination. Penta-
chlorophenol may be synthesized when phenol is chlorinated under appro-
priate conditions. Thus, in many cases chlorination of wastewater or
drinking water may result in the formation of chlorophenols rather than
in the destruction of these potentially hazardous compounds.
Food contamination by trichlorophenols and tetrachlorophenols may
occur if residues accumulate and persist in edible portions of crops,
fish, or domestic animals. Domestic animals and agricultural crops could
also become contaminated indirectly with trichlorophenols and tetrachloro-
phenols by absorption and/or ingestion followed by degradation of the
pesticides 2,4,5-T, silvex, lindane, and pentachlorophenol. For example,
lindane absorbed by lettuce plants is metabolized to free and conjugated
2,3,4,6-tetrachlorophenol. No information is available, however, on the
presence and metabolic fate of trichlorophenols and tetrachlorophenols
in field-grown crops arising from the absorption and eventual metabolism
of the above pesticides. Residues of 2,4,5-trichlorophenol have been
found in the kidney and liver of sheep and cattle fed very high concen-
trations of 2,4,5-T and silvex. 2,4,5-Trichlorophenol has also been
found in milk and cream of cows fed diets containing large amounts
(1000 mg/kg body weight) of 2,4,5-T. It seems unlikely, however, that
the large quantities of 2,4,5-T and silvex required to produce detectable
concentrations of 2,4,5-trichlorophenol in domestic animals are likely to
be found in feed, forage, and pastures. Proper usage of the herbicide
should result in negligible residues of 2,4,5-trichlorophenol in meat and
milk. Direct exposure of domestic animals to trichlorophenols and tetra-
chlorophenols seems unlikely; however, some low-level contamination may
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result when herbicide formulations contaminated with chlorophenols are
applied to fields and pastures. The possibility that trichlorophenols
or tetrachlorophenols may accumulate in fish and other edible aquatic
organisms has not been well studied. If this phenomenon does occur,
tetrachlorophenols would be the most likely candidates for accumulation
in aquatic organisms. This question warrants further study.
Because musty taint in chickens may result from exposure to chloro-
phenols, wood shavings which contain chlorophenols should not be used as
litter material for broiler chickens or domestic animals. Unfortunately,
wood shavings are used extensively as a cheap source of litter for broiler
chickens, turkeys, ducks, pigs, and cattle; thus, the danger that preserva-
tive-treated wood may be included in these shavings exists. Furthermore,
spent litter is being used increasingly as a constituent of animal feeds.
Despite this potential hazard, limited information indicates that con-
tamination of foodstuff by residues of trichlorophenols and tetrachloro-
phenols is unlikely, and transfer to humans through the food chain appears
to be remote. Direct exposure during the manufacture of these compounds
apparently constitutes the major hazard.
No information is available on the long-term chronic toxicity of
2,4,5- and 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol; there-
fore, the degree of hazard posed by chronic exposure is speculative.
2,3,4,6-Tetrachlorophenol is the most toxic of these compounds, but it
apparently degrades readily in soil and aquatic environments. No data
are available, however, to conclusively prove these contentions. More
definitive investigations are needed to assess the environmental hazards
associated with use of these compounds.
Another possible hazard associated with the use of chlorophenols is
that these compounds may be contaminated with, or give rise to, chloro-
dibenzo-p-dioxins. Some chlorodioxins are known to have extremely high
toxicity and teratogenicity, and their presence, even in extremely low
quantities, poses a definite hazard. Chlorodioxins associated with the
use of trichlorophenols and tetrachlorophenols could be introduced into
the environment in two ways: (1) by contamination of commercially pro-
duced higher chlorophenols with chlorodioxins and (2) by pyrolytic con-
densation of higher chlorophenols to chlorodioxins following incomplete
incineration of solid waste containing chlorophenols, especially wood.
Modern procedures reduce the formation of chlorodioxins during chlorophenol
manufacture, but possible production of chlorodioxins during pyrolysis or
through presently unknown reaction pathways has not been explored and
warrants further consideration.
C.I.2 CONCLUSIONS
1. Gas-liquid chromatography is the best method for the separation,
identification, and quantification of low levels of 2,4,5-tri-
chlorophenol, 2,4,6-trichlorophenol, and tetrachlorophenols in
environmental samples.
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2. 2,4,5-Trichlorophenol, 2,4,6-trichlorophenol, and tetrachlorophenols
are toxic to microorganisms; effects on cell permeability and oxida-
tive phosphorylation are probable mechanisms of action.
3. Microbial toxicity is pH dependent; the undissociated form of
chlorophenol is more toxic than the dissociated form.
4. Limited information indicates that highly chlorinated phenols are
toxic to vascular plants. Toxicity roughly corresponds with the
degree of chlorination: 2,3,4,6-tetrachlorophenol > 2,4,5-tri-
chlorophenol > 2,4,6-trichlorophenol.
5. No documented toxic effects of trichlorophenols and tetrachlorophenols
on domestic animals or wildlife were found.
6. Trichlorophenols and tetrachlorophenols may appear in domestic animals
following absorption of chemically related herbicides (e.g., 2,4,5-T,
silvex, lindane, ronnel, and erbon).
7. Musty taint may occur in broiler chickens when trichlorophenols or
tetrachlorophenols in chicken litter are methylated (with production
of the corresponding anisoles) by fungi and absorbed by the chickens.
8. Information on the toxicity of trichlorophenols and tetrachlorophenols
to aquatic organisms is needed.
9. Documented cases of human systemic toxicity due to exposure to tri-
chlorophenols or tetrachlorophenols are not available.
10. 2,4,5-Trichlorophenol and 2,4,6-trichlorophenol are not readily
absorbed through the skin, but 2,3,4,6-tetrachlorophenol dissolved
in organic solvents may be absorbed directly through the skin in
acutely toxic amounts.
11. Trichlorophenols are mildly toxic (LD5o values as high as 3 g/kg body
weight in rats), but tetrachlorophenols pose a more severe acute
toxicity hazard (LD50 values between 120 and 250 mg/kg body weight
in experimental mammals).
12. Long-term exposure to trichlorophenol formulations has caused
chloracne in humans, but affected individuals were exposed to a
wide variety of chemicals (including 2,3,7,8-tetrachlorodibenzo-p-
dioxin, a known impurity in technical chlorophenol formulations,
which can cause chloracne).
13. 2,4,5-Trichlorophenol promotes the appearance of tumors in mice
following an initiating dose of dimethyIbenzanthracene but does
not cause tumors in the absence of an initiator. No tumor-promoting
activity was found for 2,4,6-trichlorophenol tested in the same
system.
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14. 2,4,5-Trichlorophenol is not teratogenic or embryo toxic to rats.
2,4,6-Trichlorophenol and tetrachlorophenols have not been tested
for these effects.
15. Monitoring data on the presence of trichlorophenols and tetrachloro-
phenols in air, water, or soil are not available.
16. Likely sources of trichlorophenol and tetrachlorophenol contamina-
tion of soil and water are (1) chlorination of phenol or the lower
chlorophenols during wastewater or drinking water chlorination pro-
cedures, (2) direct addition of the chemicals from industrial sites
to waterways, and (3) degradation products of commonly used pesti-
cides (e.g., 2,4,5-T and silvex).
17- Limited evidence indicates the rapid microbiological degradation of
2,4,5- and 2,4,6-trichlorophenol in aquatic environments, activated
sludge, and aeration lagoon effluent.
18. More research is warranted on the persistence and degradation of
tetrachlorophenols in soils and water.
19. Disruption of normal sewage treatment processes may occur if tri-
chlorophenols or tetrachlorophenols are dumped or allowed to seep
into waste treatment facilities not normally exposed to the compounds.
20. Preliminary data indicate that trichlorophenols and tetrachloro-
phenols are probably not tightly bound to soil particles, and under
appropriate conditions, leaching through the soil profile is expected.
Groundwater contamination has not been documented.
21. Chlorine substitution in the meta position appears to interfere
with microbial decomposition of chlorophenols; thus, 2,4,5-tri-
chlorophenol will probably persist much longer in the environment
than either 2,4,6-trichlorophenol or 2,3,4,6-tetrachlorophenol.
22. Chronic toxicity of trichlorophenols or tetrachlorophenols to humans
or other organisms has not been documented.
23. Food contamination with trichlorophenols and tetrachlorophenols is
minimal, and transfer to humans through the food chain appears to
be remote.
24. The environmental hazards posed by commonly found impurities in
chlorophenol formulations (i.e., chlorodibenzo-p-dioxins) need
further assessment.
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C.2 CHEMICAL AND PHYSICAL PROPERTIES AND ANALYSIS
C.2.1 PHYSICAL PROPERTIES
Some physical properties of trichlorophenols and tetrachlorophenols
are given in Table A.2.1. These chemicals are insoluble in water but
readily dissolve in many organic solvents (Doedens, 1963). This property
provides a method of isolating the compounds for analysis. All trichloro-
phenols and tetrachlorophenols behave as weak acids, although the latter
are stronger acids. Furthermore, tetrachlorophenols may volatilize less
than trichlorophenols.
C.2.2 MANUFACTURE
The commercial synthesis of 2,4,6-trichlorophenol is readily accom-
plished by the direct chlorination of phenol (Doedens, 1963). Monochloro-
phenols and dichlorophenols obtained as by-products are removed either
by fractional distillation or are converted to the desired product by
recycling and further chlorination. Manufacturers of 4-chlorophenol and
2,4-dichlorophenol dispose of the by-products 2-chlorophenol and 2,6-di-
chlorophenol by chlorinating them to 2,4,6-trichlorophenol. 2,4,6-Trichloro-
phenol has also been prepared by the diazotization of 2,4,6-trichloroaniline
followed by the hydrolysis of diazonium salt. The production of 2,4,5-
trichlorophenol involves the hydrolysis of 1,2,4,5-tetrachlorobenzene in
the presence of methanol and sodium hydroxide (Doedens, 1963). After
hydrolysis the main impurity is 2,4,5-trichloroanisole, which is formed
by the reaction of 2,4,5-trichlorophenol and methanol; it is removed by
organic solvent extraction and 2,4,5-trichlorophenol is recovered by
distillation. This isomer may also be prepared by the diazotization of
2,4,5-trichloroaniline.
2,3,4,6-Tetrachlorophenol can be prepared by direct chlorination of
phenol with catalysts such as iodine and iron chloride (Doedens, 1963).
However, in industry, the starting materials for its production may be a
mixture of 2-chlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol,
which are available if the company is a primary producer of 4-chloro-
phenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol. The compound can
also be synthesized by reducing 1,2,4,4,5,6,6-heptachlorocyclohexen-l-
one-3 with stannous chloride/hydrochloric acid/acetic acid or with potas-
sium iodide/acetic acid. The preparation of 2,3,4,5-tetrachlorophenol is
accomplished either by diazotization of 2,3,4,5-tetrachloroaniline or by
hydrolysis of pentachlorobenzene in the presence of methanol and sodium
methylate (Doedens, 1963). 2,3,5,6-Tetrachlorophenol can be synthesized
from 2,3,5,6-tetrachloroaniline through diazotization or as a coproduct
with 2,3,4,5-tetrachlorophenol in the hydrolysis of pentachlorobenzene
(Doedens, 1963).
C.2.3 USES
2,4,6-Trichlorophenol is used as a bactercide and fungicide in the
preservation of wood, leather, and glue and in the treatment of mildew
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on textiles (Doedens, 1963; Dow Chemical Company, undated). Its effec-
tiveness is reported to be higher than that of monochlorophenols and
dichlorophenols. It is also useful as an ingredient in the preparation
of insecticides and soap germicides. The primary use of 2,4,5-trichloro-
phenol is as an intermediate for the synthesis of pesticides, notably the
herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and its derivatives
(Doedens, 1963; Dow Chemical Company, undated). This herbicide provides
effective brush control, and it was used widely in Vietnam for defolia-
tion. 2,4,5-Trichlorophenol and its sodium salts are also used directly
as germicides and as ingredients of soap germicides.
The chief applications of 2,3,4,6-tetrachlorophenol and its salts
include use as germicides for the preservation of wood, latex, and
leather and as insecticides (Doedens, 1963). 2,3,4,5-Tetrachlorophenol
and 2,3,5,6-tetrachlorophenol do not have any commercial importance
(Doedens, 1963).
C.2.4 CHEMICAL REACTIVITY
Electrophilic substitution readily occurs in the aromatic ring of
2,4,6-trichlorophenol through halogenation (Doedens, 1963). Chlorina-
tion results in the formation of 2,3,4,6-tetrachlorophenol and penta-
chlorophenol; bromination yields the monosubstituted and disubstituted
derivatives. Direct nitration is difficult because nitration reagents
easily oxidize the compound to the benzoquinone derivative. Treatment
of 2,4,6-trichlorophenol with chlorine and fuming sulfuric acid results
in preparation of the insecticide chloranil (2,3,5,6-tetrachloro-l,4-
benzoquinone). 2,4,6-Trichlorophenol reacts with formaldehyde to form
a bis (methylene) derivative and with sulfuric chloride to give 3,3'-
dihydroxy-2,4,6,2',4',6'-hexachlorodiphenyl sulfide, both of which are
soap germicides. The phenolic group of 2,4,6-trichlorophenol reacts
like phenol; ethers, esters, amine compounds, and metallic salts have
been reported (Doedens, 1963).
Substitution can also occur in the aromatic ring of 2,4,5-trichloro-
phenol. It can be brominated and nitrated to the monosubstituted and
disubstituted derivatives (Doedens, 1963). 2,4,5-Trichlorophenol reacts
with formaldehyde and sulfuryl chloride to yield the bis (methylene) and
thiobis derivatives, respectively, both of which are soap germicides.
The phenolic group of 2,4,5-trichlorophenol undergoes interesting reac-
tions which yield important pesticidal compounds. It reacts with thio-
phosphoryl chloride and then with sodium methylate in the presence of
methanol to produce ronnel [0,0-dimethyl 0-(2,4,5-trichlorophenyl) phos-
phorothioate], a phosphate insecticide. The manufacture of 2,4,5-T
involves etherification of 2,4,5-trichlorophenol with chloroacetic acid
in the presence of sodium hydroxide. Reaction of 2,4,5-trichlorophenol
with 2-monochloropropionic acid yields silvex [2-(2,4,5-trichlorophenoxy)-
propionic acid]. Metal trichlorophenates are prepared by reacting 2,4,5-
trichlorophenol with metal salts in the presence of organic solvents
(Doedens, 1963).
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162
Salts of 2,3,4,6-tetrachlorophenol are manufactured easily by
reacting the compound with metal salts in mixtures of organic solvents
(Doedens, 1963).
In summary, trichlorophenols undergo several reactions which yield
important products such as pesticides and soap germicides. Salts of
2,4,6- and 2,4,5-trichlorophenol and 2,3,4,6-tetrachlorophenol are
readily prepared. In salt form the chemicals are more soluble in water.
Apparently, the reactions described do not occur in the natural environ-
ment. One reaction that 2,4,6-trichlorophenol may undergo in water is
oxidation to hydroquinone during chlorination (Burttschell et al., 1959).
C.2.5 TRANSPORT AND TRANSFORMATION IN THE ENVIRONMENT
The transport and transformation mechanisms of 2,4,5- and 2,4,6-
trichlorophenol (use of the term tirichloTOphenols in the subsequent dis-
cussion refers only to these isomers) and of tetrachlorophenols in air,
soil, and aquatic environments are discussed fully in Section C.7. A
summary is presented here to give perspective on the possible relation-
ship of the physical and chemical properties of the chemicals to their
interactions with the different segments of the environment.
C.2.5.1 Air
Trichlorophenols and tetrachlorophenols are relatively volatile, and
volatilization is probably the major dispersal mechanism of the chemicals
to the atmosphere. However, monitoring data are lacking, making it dif-
ficult to determine transportation and transformation mechanisms.
C.2.5.2 Aquatic Environment
Trichlorophenols and tetrachlorophenols may be present in the aquatic
environment either in dissolved form, associated with suspended matter or
bottom sediments, or absorbed by organisms. Metal salts of these com-
pounds have greater water solubility, and if introduced, they would exist
primarily in the dissolved form. The tendency of chlorophenols to ionize
depends on the pH of the system. They are nonionized in aqueous solutions
with pH lower than 5 and become increasingly dissociated as the pH rises.
The degree of dissociation could determine the extent of sorption of tri-
chlorophenols and tetrachlorophenols by colloids in aquatic systems; how-
ever, specific information is not available. Hydrological factors such
as current patterns and mixing as well as sorption, degradation, and
migration of organisms affect the movement of these chemicals.
There is limited evidence which indicates the microbiological degra-
dation of 2,4,5- and 2,4,6-trichlorophenol in aquatic environments.
Mixed microbial populations found in activated sludge and waste lagoons
degrade these chemicals readily (Ingols, Gaffney, and Stevenson, 1966;
Sidwell, 1971).
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163
C.2.5.3 Soils
The movement of trichlorophenols and tetrachlorophenols in soils de-
pends largely on the interaction and persistence of the chemicals. The
extent of sorption determines whether the chemicals are carried in asso-
ciation with eroded soils or move through the soil profile with water.
Sorption characteristics of trichlorophenols and tetrachlorophenols have
not been studied. Due to their weakly acidic properties and low water
solubilities, they may be sorbed substantially by soil colloids, particu-
larly the organic colloids.
Available data indicate that microorganisms play an important role
in the dissipation of trichlorophenols and tetrachlorophenols in the
environment. Bacterial species capable of metabolizing 2,4,6-trichloro-
phenol and 2,3,4,6-tetrachlorophenol have been isolated from soils and
activated sludge (Tabak, Chambers, and Kabler, 1964; Nachtigall and
Butler, 1974). In addition, certain species of fungi and mixed bacterial
populations found in broiler house litters can degrade 2,3,4,6-tetra-
chlorophenol (Gee and Peel, 1974). This degradation may be an important
removal mechanism for trichlorophenols and tetrachlorophenols present in
wood shavings used for litter.
Persistence of trichlorophenols and tetrachlorophenols appears to
depend on the position of the chlorine atoms on the aromatic ring.
Isomers with chlorine in the meta position seem to degrade less readily
in soils (Alexander and Aleem, 1961), indicating that 2,4,5-trichlorophenol
and the tetrachlorophenol isomers persist longer in the environment. In
contrast, Ide et al. (1972) found rapid disappearance of tetrachlorophenols
in flooded soils, with 2,3,4,6-tetrachlorophenol degrading the fastest.
Factors affecting the persistence of these chlorophenols need further study.
C.2.6 ANALYSIS
C.2.6.1 Sampling, Storage, and Preservation
Sample collection, handling, and storage techniques for trichloro-
phenols and tetrachlorophenols are essentially the same as those described
for 2-chlorophenol and 2,4-dichlorophenol in Section B.2.6.1.
C.2.6.2 Sample Preparation for Analysis
The methods of preparation used for samples to be analyzed for tri-
chlorophenols and tetrachlorophenols are the same as those used for 2-
chlorophenol and 2,4-dichlorophenol (Section B.2.6.2).
C.2.6.3 Determination and Identification
The methods for detection of trichlorophenols and tetrachlorophenols
in environmental samples are the same as those used for 2-chlorophenol
and 2,4-dichlorophenol: colorimetry, chromatography, ultraviolet and
infrared spectrophotometry, and mass spectrometry (Table C.2.1). See
-------
TABLE C.2.1. METHODS OF DETERMINATION OF 2,4,5-TRICHLOROPHENOL, 2,4,6-TRICHLOROPHENOL, AND TETRACHLOROPHENOLS
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Source
Aqueous solution of 2-chloro-
phenol, 2,4-dichlorophenol,
and 2,4,5-trichlorophenol
2,3,4,6-Tetrachlorophenol in
fats, oils, and fatty acids
2,4-Dichlorophenol, 2,4,5- and
2,4,6-trichlorophenol in
natural waters
2,4,6-Trichlorophenol and
2,3,4,6-tetrachlorophenol
in mixtures of standard
chlorophenols
2-Chlorophenol, 2,4-dichloro-
phenol, and 2,3,4,5-tetra-
chlorophenol in mixtures
of standard phenols
2,3,4,6-Tetrachlorophenol in
wood shavings and chicken
tissues.
2-Chlorophenol, 2,4-dichloro-
phenol, and 2,4,6-trichlo-
rophenol in mixtures of
standard chlorophenols
Samples extracted with hexane and
dansyl derivatives of chloro-
phenols separated by thin-layer
chromatography
5-g samples treated with H3SO<.
and Celite, followed by liquid-
liquid extractions with petro-
leum ether, aqueous alkali,
and CHClj
1000-ml acidified samples
extracted with petroleum ether
Phenols methylated with
diazomethane
Phenols separated on a polyacry-
late resin column
200 g of wood shavings or 50 g
of chicken tissue steam dis-
tilled; distillate extracted
with pentane and extract ethyl-
ated with dlazoethane
Fluorescence spectrometry
of dansyl derivatives
Gas-liquid chromatography
using electron-capture
detector at level of 0.5
Ug/ml
Two-dimensional thin-layer
chromatography at 1
Ug/liter
Flame-ionization gas-liquid
chromatography
High-pressure liquid chrom-
atography with uv
detector
Gas-liquid chromatography
using electron-capture
detector at 10 ng/g for
wood and 0.1 to 1 ng/g
for chicken tissue
Gas-liquid chromatography
In situ measurement of flu-
orescence on thin-layer
chromatographic plate;
confirmation analysis of
derivatives by mass
spectroscopy
Recovery values ranged from
35% to 50%.
No interferences found with
coextractives
Difficulties encountered
with tailing avoided by
preparation of anisole
derivatives; derivatives
confirmed by mass
spectrometry
Elution of 21 phenols
described
Simultaneous analysis of
chloroanisoles and cor-
responding chlorophenols
possible; ethylation
improves chlorophenol
resolution.
Comparable data obtained
by gas-liquid chromatog-
raphy and infrared
spectrometry
Frei-HSusler, Frei,
and Hutzinger, 1973
Hlgginbotham, Ress,
and Rocke, 1970
Zigler and Phillips,
1967
Svec and Zbirovsky,
1974
Fritz and Willis,
1973
Gee, Land, and
Robinson, 1974
Barry, Vasishth, and
Shelton, 1962
(continued)
-------
TABLE C.2.1 (continued)
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Source
2,4,6-Trichlorophenol and
2,3,4,6-tetrachlorophenol in
organic tissue
2,4,6-Trichlorophenol and
2,3,4,6-tetrachlorophenol in
soil
2,4,6-Trichlorophenol and
2,3,4,6-tetrachlorophenol in
water
Tetrachlorophenol in air
Tetrachlorophenol in human urine
2,4-Dichlorophenol and 2,4,5-
trichlorophenol in rat urine
2,4-Dichlorophenol, 2,4,5- and
2,4,6-trichlorophenol, and
2,3,4,5- and 2,3,4,6-tetra-
chlorophenol in rabbit urine
10-g sample homogenized with a
mixture of hexane and acetone,
followed by extraction with a
mixture of acidified hexane
and diethy1 ether; compounds
sorbed by an anion-exchange
resin and resin extracted
with benzene; extract methyl-
ated with diazomethane
10 g of soil extracted with NaOH;
extract shaken with anion-
exchange resin and resin
extracted with benzene; deriv-
atives formed with diazomethane
1000 ml of water percolated
through an anion-exchange resin;
resin extracted with benzene;
derivatives formed with
diazomethane
Air passed through alkali absorb-
ing solution and treated with
potassium ferrlcyanide and 4-
aminoantipyrine
Acidified sample distilled, fol-
lowed by extraction of distil-
late with xylene
1- to 5-ml samples hydrolyzed
with H2SO<, followed by extrac-
tion with ethyl ether and
ethylation with diazoeth^ne;
eluted from silica gel column
with benzene-hexane
Extracted with diethyl ether,
concentrated by distillation;
eluted from silica gel column
successively with hexane and
benzene in hexane; eluate
extracted with NaOH
Gas-liquid chromatography
using electron-capture
detector at levels of
0.1 to 1.0 ng/g
Fortified samples; ion
exchange for cleanup
Renberg, 1974
Gas-liquid chromatography
using electron-capture
detector at levels of
0.1 to 1.0 ng/g
Gas-liquid chromatography
using electron-capture
detector at levels of
1 to 100 ng/liter
Colorimetry
Colorimetry
Gas-liquid chromatography
using electron-capture
detector at levels of
0.1 mg/liter for 2,4-
dichlorophenol and 0.1
ng/liter for 2,4,5-
trichlorophenol
Thermal-conductivity gas-
liquid chromatography
Fortified samples; ion
exchange for cleanup
Fortified samples; ion
exchange for cleanup
and concentration
Silica gel chromatography
for cleanup; no inter-
ference from impurities
eluted by benzene
Silica gel column for
cleanup; confirmation by
infrared mass spectrometry
of chlorophenols and/or
anisole derivatives; Ras-
liquid chromatography with
electron-capture detector
unsuitable because of
tailing and nonreproduc-
ible detector response
Renberg, 1974
Renberg, 1974
Akisada, 1965
Akisada, 1965
Shafik, Sullivan, and
Enos, 1973
Karapally, Saha, and
Lee, 1.973
Ul
(continued)
-------
TABLE C.2.1 (conLinuuil)
Sample
Isolation method
2,4-Dichlorophenol, 2,4,5- and
2,4,6-trichlorophenol tn
mouse urine
2,4-Dichlorophenol and 2,4,5-
trichlorophenol in milk and
cream
2,4-Dichlorophenol and 2,4,5-
trichlorophenol in sheep and
cattle tissues
2-Chlorophenol, 2,4-dichloro-
phenol, and 2,4,5- and
2,4,6-trichlorophenol in
water
2-Chlorophenol, 2,4-dichloro-
phenol, and 2,4,6-trichlo-
rophenol in water
Partitioned into benzene and
water; phenols determined In
both phases
10-g acidified sample extracted
with diethyl ether, eluted
through alumina column with
diethyl ether, followed by
series of extractions of
eluate with dilute NaOH
and benzene
5-g sample acid hydrolyzed with
or without prior alkaline
digestion; codistilled with
water followed by partitioning
into methylene chloride forma-
tion of trimethylsilyl ether
Chlorophenols absorbed on acti-
vated carbon, adsorbates
removed by stepwise extraction
with CHClj, NaOH, and diethyl
ether
Sample used to prepare 4-amino-
antipyrine and p-nitrophenylazo
dye derivatives and extracted
with CHCls or ether
Analytical method
and sensitivity
Remarks
Source
Thermal-conductivity gas-
liquid chromatography
Gas-liquid chromatography
using microcoulometric
or electron-capture
detector at levels of
0.05 ug/ml
Gas-liquid chromatography
at levels of 0.01 to
0.02 pg/g
Thin-layer chromatography
used for purification of
compounds; enzyme hydrol-
y.sis of water-soluble
chlorophenol conjugates;
confirmation by ma.ss
fragmentography
Column chromatography for
cleanup; NaOH or benzene
extraction of eluate un-
necessary for 2,4,5-tri-
chlorophenol; recovery
>80%
Distillation for cleanup;
no interference of co-
extractives; alkaline
digestion increases
recovery; recovery >95X
Gas-liquid chromatography Florisil column for cleanup
Thin-layer chromatography
Kurihara and
Nakajima, 1974
Bjerke et al ., 1972
Clark et al., 1975
I-1
ON
ON
Eichelberger,
Dressman, and
Longbottom, 1970
Aly, 1968
-------
167
Section B.2.6.3 for discussions of the 4-aminoantipyrine colorimetric
method and thin-layer chromatography.
Gas-liquid chromatography, the most widely used technique for
separating, identifying, and quantifying chlorophenols in various kinds
of samples, employs either electron-capture or flame-ionization detec-
tors (Table C.2.1). Because gas-liquid chromatography is sensitive to
nanogram levels, it is adaptable for the quantitation of trace amounts
of chlorophenols. Although thin-layer chromatography can resolve chlo-
rophenols satisfactorily, it is, at best, semiquantitative. Gas-liquid
chromatography has been used for analysis of water and wastewater con-
taining mixtures of chlorophenol isomers after extraction and cleanup of
samples (Eichelberger, Dressman, and Longbottom 1970; Sidwell, 1971; Manu-
facturing Chemists Association, 1972). The order of elution of isomers
resulting from the chlorination of phenols in water (Manufacturing Chem-
ists Association, 1972) and in chlorophenolic wastewater (Sidwell, 1971)
is 2-chlorophenol, phenol, 2,6-dichlorophenol, 2,5-dichlorophenol, 2,4-
dichlorophenol, 2,4,6-trichlorophenol, 4-chlorophenol, and 2,4,5-tri-
chlorophenol. 2,4,5-Trichlorophenol and/or its 2,4,6- isomer have been
identified as major degradation products in the metabolism of lindane
(hexachlorocyclohexane) in rabbits (Karapally, Saha, and Lee, 1973), rats
(Freal and Chadwick, 1973), and mice (Kurihara and Nakajima, 1974). Gas-
liquid chromatography has also been utilized successfully in identifying
2,4,5-trichlorophenol as the prime metabolite of the mammalian metabolism
of the pesticides 2,4,5-T (Bjerke et al., 1972; Clark et al., 1975) and
ronnel (Shafik, Sullivan, and Enos, 1973) and in identifying 2,4,6-tri-
chlorophenol and 2,3,4,6-tetrachlorophenol in oils and fatty acids (Hig-
ginbotham, Ress, and Rocke, 1970), in fortified biological tissues, and
in soils (Gee, Land, and Robinson, 1974; Renberg, 1974). The degradation
products of pentachlorophenol in rice soils consisted mainly of tetra-
chlorophenol and some trichlorophenol isomers and were quantified by gas
chromatography (Ide et al., 1972; Kuwatsuka and Igarashi, 1975).
Biological samples such as animal tissues and soils require more
extensive cleanup than water samples before they are suitable for gas-
liquid chromatography. Problems of poor resolution and tailing encoun-
tered on samples can be corrected by judicious selection of columns and
type of derivatization (Barry, Vasishth, and Shelton, 1962; Kilgore and
White, 1970; Karapally, Saha, and Lee, 1973; Shafik, Sullivan, and Enos,
1973; Svec and Zbirovsky, 1974; Gee, Land, and Robinson, 1974; Kurihara
and Nakajima, 1974; Renberg, 1974). This is an important prerequisite
because isomers may have the same retention time. For example 2,4,5-
and 2,4,6-trichlorophenol and 2,3,5,6-tetrachlorophenol have the same
retention time on 15% OV-17 and 5% QF-1 columns (Kilgore and White, 1970;
Karapally, Saha, and Lee, 1973). Both 2,3,4,6- and 2,3,4,5-tetrachloro-
phenol have the same retention time on a 15% OV-17 column (Karapally,
Saha, and Lee, 1973); however, their methyl ether (anisole) derivatives,
formed by reacting the isomers with diazomethane, are separated easily
on the same column. Svec and Zbirovsky (1974) claimed that the anisole
derivatives were more volatile than the free chlorophenols and that the
chromatographic peaks were sharp and symmetrical. Methylation using
dimethyl sulfate (Ide et al., 1972) and ethylation with diazomethane
-------
168
(Shafik, Sullivan, and Enos, 1973; Gee, Land, and Robinson, 1974) also
improve the resolution and identification of trichlorophenols and
tetrachlorophenols (Shafik, Sullivan, and Enos, 1973; Gee, Land, and
Robinson, 1974). Use of dual columns could improve the separation of
the higher chlorinated isomers, as suggested by Barry, Vasishth, and
Shelton (1962). Columns reported to be satisfactory for the segrega-
tion of the anisole derivatives of trichlorophenols and tetrachlorophenols
include 5% QF-1 on 80/100-mesh Chromaton N-HMDS-AW (Svec and Zbirovsky,
1974), 5% QF-1 on 70/80-mesh Chromosorb G-DMCS-AW (Kilgore and White,
1970), 15% OV-17 on Chromosorb W (Karapally et al., 1973), 10% Carbowax
20M or 10% Apiezon L on 80/100-mesh CQ Celite (Gee, Land, and Robinson,
1974), and 8% QF-1 and 4% SF-96 on 100/120-mesh Chromosorb W (Renberg,
1974), 4% SE-30 and 6% QF-1 on 80/100-mesh Chromosorb W-HP (Shafik,
Sullivan, and Enos, 1973), and 1.5% neopenthyl glycol succinate on 60/80-
mesh Chromosorb W-AW (Kurihara and Nakajima, 1974). Separation of 2,4,6-
and 2,4,5-trichlorophenol from extracts of water, milk, and animal tissues
is accomplished by using 15% K20M Carbowax TPA on 80/100-mesh Chromosorb
W-HMDS (Manufacturing Chemists Association, 1972), 1.5% FFAP (free fatty
acid phase) on 100/120-mesh Chromosorb G-AW-DMCS (Sidwell, 1971), 3% OV-1
on 80/90-mesh Chromosorb W (Clark et al., 1975), and 4% LAC-446 and 0.55%
phosphoric acid on 80/100-mesh Chromosorb W-HP (Bjerke et al., 1972).
2,3,4,6-Tetrachlorophenol can be separated from oils and fats by using
10% diethylene glycol succinate and 2% phosphoric acid on a 60/80-mesh
Gas Chrom P column (Higginbotham, Ress, and Rocke, 1970). 2,4,6-Tri-
chlorophenol and 2,3,5,6-, 2,3,4,6-, and 2,3,4,5-tetrachlorophenol can
be separated from rice soils with 1% DECS and 1% phosphoric acid on
Chromosorb W (Kuwatsuka and Igarashi, 1975).
Ultraviolet and infrared spectrophotometry have also been used to
identify trichlorophenols and tetrachlorophenols (Burttschell et al.,
1959; Barry, Vasishth,. and Shelton, 1962). However, these methods are
less sensitive than gas-liquid chromatography and are probably more useful
for confirmatory tests than for quantitative analysis. Mass spectrometry
is also used for confirmatory analysis (Ide et al., 1972; Frei-HMusler,
Frei, and Hutzinger, 1973; Karapally, Saha, and Lee, 1973; Kurihara and
Nakajima, 1974; Safe, Jamieson, and Hutzinger, 1974; Svec and Zbirovsky,
1974), but this technique is complex and expensive. All of these methods
require prior separation of the compound of interest before identification
is made.
-------
169
SECTION C.2
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171
26. Safe, S., W. D. Jamieson, and 0. Hutzinger. 1974. Ion Kinetic
Energy Spectroscopy: A New Mass Spectrometric Method for the Unam-
biguous Identification of Isomeric Chlorophenols. In: Mass Spec-
trometry and NMR Spectroscopy in Pesticide Chemistry. Plenum Press,
New York. pp. 61-70.
27. Shafik, T. M. , H. C. Sullivan, and H. R. Enos. 1973. Multiresidue
Procedure for Halo- and Nitrophenols: Measurement of Exposure to
Biodegradable Pesticides Yielding These Compounds as Metabolites.
J. Agric. Food Chem. 21(2):295-298.
28. Sidwell, A. E. 1971. Biological Treatment of Chlorophenolic Wastes:
The Demonstration of a Facility for the Biological Treatment of a
Complex Chlorophenolic Waste. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C.
177 pp.
29. Svec, P., and M. Zbirovsky. 1974. Gas-Liquid Chromatography as an
Analytical Tool in the Production of Pentachlorophenol and "Hexa-
chlorophenol." Sb. Vys. Sk. Chem. Technol. Praze Org. Chem. Technol.
21:39-43.
30. Tabak, H. H. , C. W. Chambers, and P. W. Kabler. 1964. Microbial
Metabolism of Aromatic Compounds: I. Decomposition of Phenolic
Compounds and Aromatic Hydrocarbons by Phenol-Adapted Bacteria. J.
Bacteriol. 87(4):910-919.
31. Zigler, M. G. , and W. F. Phillips. 1967. Thin-Layer Chromatographic
Method for Estimation of Chlorophenols. Environ. Sci. Technol.
1(1):65-67.
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172
C.3 BIOLOGICAL ASPECTS IN MICROORGANISMS
C.3.1 BACTERIA
C.3.1.1 Metabolism
The microbial degradation of trichlorophenols and tetrachlorophenols
is extensively discussed in Section C.7; therefore, only a brief over-
view is presented in this section. Microbial degradation of trichloro-
phenols and tetrachlorophenols has been examined in soils, activated
sludge, lagoon effluent, and enrichment cultures. Soil microorganisms
capable of metabolizing trichlorophenols and tetrachlorophenols have not
been identified. A Pseudomonas sp. isolated from activated sludge was
capable of oxidizing 2,4,6-trichlorophenol (Nachtigall and Butler, 1974).
Metabolic pathways were not determined. An activated sludge culture
acclimated to phenol was able to metabolize 2,4,6-trichlorophenol
(Chambers, Tabak, and Kabler, 1963; Tabak, Chambers, and Kabler, 1964).
Predominant organisms in the mixed bacterial cultures were Pseudomonas
sp., Achromobacter sp., and Flavobacterium sp. A gram-variable bacillus
designated as KC-3 (derived from a pentachlorophenol enrichment culture)
was capable of metabolizing 2,4,6-trichlorophenol and 2,3,4,6-tetrachloro-
phenol (Chu, 1972). It is not known if bacteria capable of metabolizing
the higher phenols are widespread in the environment; more research in
this area is warranted. The pathways and mechanisms of microbial metab-
olism have not been elucidated for trichlorophenols and tetrachlorophenols.
Dechlorination, hydroxylation, and ring cleavage may be involved in the
process.
Gee and Peel (1974) studied chlorophenol metabolism by mixed bacte-
rial populations isolated from broiler house litter. A mixed bacterial
suspension obtained from broiler house litter was able to metabolize
2,3,4,6-tetrachlorophenol completely within five days without the accom-
panying production of 2,3,4,6-tetrachloroanisole. No chlorophenol metab-
olism was seen when the bacteria were cultured under anaerobic conditions.
C.3.1.2 Effects
The mechanism of toxicity of higher chlorophenols to bacteria is not
completely understood. In general, the mode of antibacterial action of
phenolic compounds involves several steps: (1) adsorption to the bac-
terial cell wall, (2) inactivation of essential enzymes, and (3) finally,
lysis and death of the cell (Klarmann, 1963). Phenolic compounds bind
and denature proteins and at high concentrations are likely to act as
gross protoplasmic poisons which penetrate rapidly and rupture the cell
wall. However, chlorophenols are frequently toxic at levels too low to
denature proteins. Thus, another mechanism must be operative at these
concentration levels. An effect on cell membranes — with subsequent
leakage of cell constituents and perhaps inactivation of specific enzyme
systems — has occurred following exposure of bacteria to chlorophenols
(Goldacre and Galston, 1953; Judis, 1962, 1963). Because higher chloro-
phenols have low water solubility and high lipid solubility, their gross
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173
effect on bacteria is probably due to association with cellular lipids
and subsequent alteration of cell permeability (Baker, Schumacher, and
Roman, 1970) . Several studies have dealt with the toxicological effect
of 2,4,6-trichlorophenol on bacteria, but investigations specifically
addressing the toxicity mechanisms of 2,4,5-trichlorophenol or tetra-
chlorophenols were not found. In general, the mechanism of toxicity of
these compounds may resemble that of 2,4,6-trichlorophenol.
Judis (1962) observed the leakage of 1AC-labeled glutamate from
Escherldhia ooli cells exposed to 2,4,6-trichlorophenol. The E. coli
cells with 1£fC-labeled glutamate lost free glutamate, and the label was
incorporated into other nondiffusible compounds. Thus, leakage from the
cell, if detected, implies injury to the cell membrane integrity or to
the selective permeability mechanisms within the cell membrane. Cells
incubated for 10 min at 22°C in a solution of 2,4,6-trichlorophenol
(333 mg/liter) released ten times more radioactivity than control cells.
The author concluded that 2,4,6-trichlorophenol may exert its lethal
activity by damaging the cell membrane or systems which control membrane
permeability. In another investigation, Judis (1963) determined the
effect of 2,4,6-trichlorophenol on glucose and sodium sulfate leakage
from E. ooli,. No leakage of 14C-labeled glucose or 35S-labeled sodium
sulfate was seen at 2,4,6-trichlorophenol concentrations of 167 or 333
mg/liter, but a pronounced leakage of 1'*C-labeled glutamate was found;
this finding was consistent with the previous study. Thus, although
2,4,6-trichlorophenol exposure resulted in the leakage of glutamate from
treated cells, thereby implying membrane damage, at least two other com-
pounds did not leak in a similar manner. The mechanism of this selec-
tive effect on cell membrane permeability for different molecules is not
known. The contribution of leakage of glutamate (and possibly other
cell constituents) to the toxicity of 2,4,6-trichlorophenol to bacteria
is not known, and further research is warranted.
Goldacre and Galston (1953) demonstrated an effect of 2,4,6-tri-
chlorophenol on the in vitro activity of crystalline beef liver cata-
lase. 2,4,6-.trichlorophenol, at a concentration of 10~2 M (2 g/liter),
inhibited the catalase reaction by 50%. This effect was the weakest
among six chlorophenol compounds tested in the system. The investiga-
tors suggested that this effect on the catalase system may be responsi-
ble for some bactericidal action of chlorophenols, but additional data
are needed.
All chlorophenols possess some bactericidal properties (Klarmann,
1963; Skyes, 1965; Baker, Schumacher, and Roman, 1970). Antibacterial
effectiveness generally increases with the degree of chlorine substitu-
tion up to the trichloro derivatives. The tetrachloro isomers are con-
siderably less active than the trichloro isomers, and pentachlorophenol
is even less active. However, some of the higher chlorophenols, partic-
ularly 2,3,4,6-tetrachlorophenol and pentachlorophenol, possess enhanced
fungicidal activity. The bactericidal action of disinfectants is fre-
quently expressed in terms of the phenol coefficient (Section B.3.1).
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174
2,4,5-Trichlorophenol is produced in large quantities in the United
States, primarily as a precursor compound in the manufacture of 2,4,5-
trichlorophenoxyacetic acid (2,4,5-T). The compound is available com-
mercially under several trademark designations, and both 2,4,5-tri-
chlorophenol and its sodium salt are sold in flake form for germicidal
use (Doedens, 1963). The sodium salt of 2,4,5-trichlorophenol is mar-
keted by Dow Chemical Corporation under the trade name Dowicide B.
Antibacterial efficiencies (expressed as a concentration necessary for
growth inhibition) for the higher chlorophenols are presented in Table
A.3.1.
2,4,6-Trichlorophenol is sold commercially by a number of producers.
It is used as a bactericide, a fungicide, a general antiseptic, a wood
and glue preservative, an insecticide ingredient, and an antimildew
treatment for textiles (Doedens, 1963). Although 2,4,6-trichlorophenol
is recognized as an effective microbicide, toxicity data for various
species of bacteria are scant. Sykes (1965) reported the bactericidal
activity of 2,4,6-trichlorophenol in strains of Salmonella typhi and
Staphylococcus aureus. The phenol coefficients were 23.0 and 25.0 respec-
tively. Thus, 2,4,6-trichlorophenol is approximately 24 times more effec-
tive against these two bacterial strains than phenol.
The pH of the medium has a profound effect on the bactericidal
efficiency of chlorophenols (Howard and Durkin, 1973). Ordal (1941)
noted that 2,4,6-trichlorophenol was far more effective in inhibiting
the growth of Staphylococcus aureus at low pH. At pH 5.8, levels of
500 mg/liter 2,4,6-trichlorophenol inhibited completely the growth of
the bacterium in culture medium. On the other hand, almost 30 g/liter
was required for complete inhibition at pH 9.8. The author noted that
because the pK value of 2,4,6-trichlorophenol is 6.2, the undissociated
compound is far more germicidal to Staphylococcus aureus than is the
dissociated compound. A linear relationship exists between the loga-
rithms of the LC50 values and the solubility of the higher chlorophenols
(Blackman, Parke, and Carton, 1955). These data seem to indicate that
the toxic effect of the chlorophenols is increased as the pH of the
medium approaches the pK of the chlorophenols. Thus, the effect of pH
on toxicity must be considered when data from different laboratories and
investigators are compared.
2,4,6-Trichlorophenol may pose a hazard in sewage treatment facili-
ties. The Manufacturing Chemists Association (1972) reported that 2,4,6-
trichlorophenol caused a significant inhibition of oxygen uptake in a
mixed microbial population. Inhibition was detected in a synthetic
sewage preparation at 2,4,6-trichlorophenol concentrations of 50 and 100
mg/liter; no effect was noted at 1 or 10 mg/liter. Although this experi-
ment indicates that the compound may be capable of interfering with
sewage treatment processes, no other data directly addressing the effect
of 2,4,6-trichlorophenol on sewage treatment works are available; further
investigations are warranted.
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175
Among the tetrachlorophenol isomers, only 2,3,4,6-tetrachlorophenol
is of any commercial importance. The chief applications of the compound
and its salts are as bactericides for latex preservation, wood preserva-
tives, insecticides, and leather preservatives (Doedens, 1963).
C.3.2 FUNGI
C.3.2.1 Metabolism
Information on metabolism of 2,4,6-trichlorophenol and 2,3,4,6-
tetrachlorophenol by fungi is derived primarily from studies of musty
taint in chicken and chicken eggs (Section C.5.1.2.2.3). Musty taint
appears in chickens following methylation of 2,4,6-trichlorophenol and
2,3,4,6-tetrachlorophenol by fungi in poultry litter and subsequent ab-
sorption of the anisoles by the chickens. Many species of fungi com-
monly present in poultry litter are capable of methylating chlorophenols
to their corresponding anisoles. Methylation of 2,4,6-trichlorophenol
to 2,4,6-trichloroanisole was demonstrated by Lane et al. (1975). Fungal
species such as Aspergillus sydowi, Scopulariops-is brevicaulis, and
Penic-illiiun crustoswn were capable of catalyzing the methylation reac-
tion, but mechanisms for the reaction were not determined.
Efficient methylation of 2,3,4,6-tetrachlorophenol by a number of
fungal species present in poultry litter was reported by Curtis et al.
(1972, 1974). Gee and Peel (1974) screened 26 fungal species for ability
to metabolize and methylate 2,3,4,6-tetrachlorophenol over a five-day
period. The experiments were designed to determine if the ability to
metabolize chlorophenols is widespread among litter microorganisms and
the extent to which metabolism is associated with methylation. Gee and
Peel used 116 isolates of 26 fungal species found in poultry litter; 99
of the 116 isolates tested were capable of metabolizing chlorophenol
(assayed by disappearance of the compound from the culture medium) and
68 of them produced 2,3,4,6-tetrachloroanisole (as assayed by the appear-
ance of the compound in the medium) . Some of the isolates metabolized
most of the chlorophenol but did not produce 2,3,4,6-tetrachloroanisole
(e.g., Pen-io-ilUwn brevi-cornpactum). This information suggests that two
different pathways exist for the utilization of 2,3,4,6-tetrachlorophenol
by fungi and that only one involves methylation to the chloroanisole
(Table C.3.1). The percentage of 2,3,4,6-tetrachlorophenol methylated
differed widely among isolates, even isolates of the same species. The
greatest methylation was observed with Penic-illiim corylophilum.
C.3.2.2 Effects
The antifungal activities of 2,4,5-trichlorophenol, 2,4,6-trichloro-
phenol, and 2,3,4,6-tetrachlorophenol have been documented; their toxicities
to various species of fungi are presented in Table A.3.3. Information on
the mechanism of toxic action of higher chlorophenols to fungi is not
available; toxicity may result from mechanisms similar to those discussed
for bacteria (Section C.3.1.2). Reported effects on oxidative phosphoryla-
tion (Section C.6.2.2.1) may also be important in the toxicity of these
chlorophenols to fungi.
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176
TABLE C.3.1. METABOLISM OF 2,3,4,6-TETRACHLOROPHENOL BY
FUNGAL ISOLATES
2,3,4, 6-Tetrachlorophenol
Fungal species
Absi-dia cylindrospora
Aspevgillus amstelodami
A . candidus
A. chevalieri
A. chevalieri var. intermedius
A. clavatus
A. fiavus
A. fUwus var. colunrnaris
A. niger
Isolate , . ,b
Metabolized
CDS
CD119
UD323
US90
US11
US196
US28
US177a
M29^
US189
US46
S44&
T3^
US78b
M33*
US66
US52
US10
US63
US50
US13
US264
rei2'
F44^
F68^
US71
US67
US222
US77
UD33
UD215
CS14
UD314
CS142
CS180
L9^
LIO^
9
0
0
95
26
25
8
72
45
15
14
10
0
0
0
27
19
12
9
0
100
32
16
13
13
0
0
0
0
4
0
35
31
17
14
4
0
Methylated
0
0
0
39
2
3
Trace
Trace
Trace
0
0
0
0
Trace
0
3
1
1
0
Trace
45
Trace
6
2
2
Trace
Trace
Trace
0
0
0
2
3
4
0
8
3
(continued)
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177
TABLE C.3.1 (continued)
2,3,4, 6-Tetrachlorophenol
Fungal species
A. petrdki>i
A. vepens
A. restrictus
A. ruber
A . sydcwi,
A. vevsioolov
A. wenirii.
Mucov racemosus
Isolate
UD130
UD51
US35
S51^
US31
US21
T24^
US142
M40^
US22
US12
US98
L14^
US43
US91
LI 3^
US97
US153
US194
S42^
M38&
US135
S37^
US15
US103
T21?3
US184
US61
US120
US228
M37^
M35^
S60^
CS112
UD271
CD56
US100
Metabolized^
99
88
99
99
99
99
97
97
99
35
14
100
92
32
28
24
18
8
100
100
97
95
92
87
83
27
22
98
89
81
69
47
37
9
30
4
0
0
Methylated
40
44
48
61
61
25
74
45
64
27
0
30
31
3
0
8
Trace
Trace
74
27
48
42
22
56
62
10
17
42
34
80
18
6
19
7
Trace
0
0
(continued)
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178
TABLE C.3.1 (continued)
2,3,4, 6-Tetrachlorophenol
Fungal species
Paeo-ilorryces varioti.
PenicilHwn t>?evi-cornpactwn
P. chrysogenwn
P. corylophilum
P. crustoswn
P. frequentans
P. roqueforti
Rhizcpus oryzae
Scopulariopsis brev-ieaulis
Isolate w , ,. ,a
Metabolized
CS18
CS21
CS84
CS11
US123
CS121b
US62
CS109
US198
US49
US75
US72
US113
US162
US160
US117
US59
T12^
R13^
US201
US185
L3^
S3323
US129
US52
CS127
US24
US30
CS121a
CS126
CS129
CS158
CS97
CS155
D6&
US178
US17
US1
100
69
34
16
100
97
28
0
52
40
35
15
98
97
96
95 .
71
57
47
46
41
38
25
16
86
30
22
4
99
72
53
12
55
0
87
52
23
20
Methylated
81
56
14
11
Trace
Trace
0
Trace
0
Trace
Trace
0
80
62
83
75
2
3
Trace
16
7
14
6
Trace
54
Trace
0
0
65
27
8
7
Trace
0
60
6
1
Trace
(continued)
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179
TABLE C.3.1 (continued)
2,3,4,6-Tetrachlorophenol
Fungal species Isolate *,,-,. -.a
6 Metabolized Methylated
US171
T8z?
M7
15
6
0
Trace
1
Trace
Taken as the difference between residual chlorophenol in treated
cultures and that found in uninoculated control cultures.
^"Isolates obtained from litter associated with musty chickens.
GA definite trace but <1%.
Source: Adapted from Gee and Peel, 1974, Table I, pp. 240-241.
Reprinted by permission of the publisher.
C.3.3 ALGAE
C.3.3.1 Metabolism
No information is available on the metabolism of 2,4,5-trichloro-
phenol, 2,4,6-trichlorophenol, or tetrachlorophenols by algae. Algae
may be capable of assimilating and metabolizing chlorophenols in the
environment, but further investigation is warranted.
C.3.3.2 Effects
As discussed previously (Section B.3.3.2), the healthy growth of
algae in waste stabilization ponds is important for reoxygenation pur-
poses, and considerable concern has been expressed over the toxic effects
of organic chemicals on the photosynthetic activity of algae. The effects
of chlorophenols on the synthesis of chlorophyll by the blue-green algae
ChloTella pyrenoidosa under laboratory conditions were investigated by
Huang and Gloyna (1967). They found that 2,4,5- and 2,4,6-trichloro-
phenol possess similar toxicological properties; both compounds seriously
affect chlorophyll synthesis at concentrations greater than 2.5 mg/liter
(Table A.3.4). Both trichlorophenol isomers are far more toxic to
Chlorella than either 2,4-dichlorophenol or the monochlorophenols. At a
concentration of 1.0 log/liter, 2,4,5- and 2,4,6-trichlorophenol showed a
minimal effect on chlorophyll synthesis; this value was accepted as a
minimum toxic level. Huang and Gloyna (1967) concluded that increasing
the number of chlorine atoms on the aromatic ring of chlorophenols en-
hanced their toxicity. Both 2,4,5- and 2,4,6-trichlorophenol may pose a
serious threat to algae in waste stabilization ponds. Care must be
taken that these compounds are not dumped or allowed to seep into such
waste treatment facilities.
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180
SECTION C.3
REFERENCES
1. Baker, J. W., I. Schumacher, and D. P. Roman. 1970. Antiseptics
and Disinfectants. In: Medicinal Chemistry, Part I, 4th ed., A.
Burger, ed. John Wiley and Sons, Interscience Publishers, New York.
pp. 627-661.
2. Blackman, G. E., M. H. Parke, and G. Carton. 1955. The Physiolog-
ical Activity of Substituted Phenols: II. Relationships between
Physical Properties and Physiological Activity. Arch. Biochem.
Biophys. 54:55-71.
3. Chambers, C. W., H. H. Tabak, and P. W. Kabler. 1963. Degradation
of Aromatic Compounds by Phenol-Adapted Bacteria. J. Water Pollut.
Control Fed. 35(12):1517-1528.
4. Chu, J. P. 1972. Microbial Degradation of Pentachlorophenol and
Related Chlorophenols. Ph.D. Thesis. Purdue University, Lafayette,
Ind. 117 pp.
5. Curtis, R. F., C. Dennis, J. M. Gee, M. G. Gee, N. M. Griffiths,
D. G. Land, J. L. Peel, and D. Robinson. 1974. Chloroanisoles as
a Cause of Musty Taint in Chickens and Their Microbiological Forma-
tion from Chlorophenols in Broiler House Litters. J. Sci. Food Agric.
25:811-828.
6. Curtis, R. F., D. G. Land, N. M. Griffiths, M. Gee, D. Robinson,
J. L. Peel, C. Dennis, and J. M. Gee. 1972. 2,3,4,6-Tetrachloro-
anisole Association with Musty Taint in Chickens and Microbiological
Formation. Nature (London) 235:223-224.
7. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons, Inter-
science Publishers, New York. pp. 325-338.
8. Gee, J. M., and J. L. Peel. 1974. Metabolism of 2,3,4,6-Tetrachlo-
rophenol by Micro-organisms from Broiler House Litter. J. Gen.
Microbiol. 85(2):237-243.
9. Goldacre, P. L., and A. W. Galston. 1953. The Specific Inhibition
of Catalase by Substituted Phenols. Arch. Biochem. Biophys. 43:169-
175.
10. Howard, P. H., and P. R. Durkin. 1973. Preliminary Environmental
Hazard Assessment of Chlorinated Naphthalenes, Silicones, Fluoro-
carbons, Benzene-polycarboxylates, and Chlorophenols. U.S. Environ-
mental Protection Agency, Washington, D.C. 263 pp.
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181
11. Huang, J. C., and E. F. Gloyna. 1967. Effects of Toxic Organics
on Photosynthetic Reoxygenation. University of Texas, Center for
Research in Water Resources, Austin. 163 pp.
12. Judis, J. 1962. Studies on the Mechanism of Action of Phenolic
Disinfectants: I. Release of Radioactivity from Carbon1U-Labeled
Escheridhia ooli. J. Pharm. Sci. 51(3):26l-265.
13. Judis, J. 1963. Studies on the Mechanism of Action of Phenolic
Disinfectants: II. Patterns of Release of Radioactivity from
EsoheviohLa ooli, Labeled by Growth on Various Compounds. J. Pharm.
Sci. 52(2):126-131.
14. Klarmann, E. G. 1963. Antiseptics and Disinfectants. In: Kirk-
Othmer Encyclopedia of Chemical Technology, 2nd ed., Vol. 2. John
Wiley and Sons, Interscience Publishers, New York. pp. 623-630.
15. Land, D. G. , M. G. Gee, J. M. Gee, and C. A. Spinks. 1975. 2,4,6-
Trichloroanisole in Broiler House Litter: A Further Cause of Musty
Taint in Chickens. J. Sci. Food Agric. 26(10) : 1585-1591.
16. Manufacturing Chemists Association. 1972. The Effect of Chlorina-
tion on Selected Organic Chemicals. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C. pp.
73-100.
17. Nachtigall, M. H. , and R. G. Butler. 1974. Metabolism of Phenols
and Chlorophenols by Activated Sludge Microorganisms (abstract).
Abstr. Annu. Meet. Am. Soc. Microbiol. 1974:184.
18. Ordal, E. J. 1941. Relative Germicidal Action of Some Halogenated
Phenols and Their Phenolates. Proc. Soc. Exp. Biol. Med. 47:387-389.
19. Sykes, G. 1965. Phenols, Soaps, Alcohols, and Related Compounds.
In: Disinfection and Sterilization, 2nd ed. E. and F. N. Spon Ltd.,
London, pp. 311-349.
20. Tabak, H. H., C. W. Chambers, and P. W. Kabler. 1964. Microbial
Metabolism of Aromatic Compounds: I. Decomposition of Phenolic
Compounds and Aromatic Hydrocarbons by Phenol-Adapted Bacteria. J.
Bacteriol. 87(4):910-919.
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C.4 BIOLOGICAL ASPECTS IN PLANTS
C.4.1 METABOLISM
C.4.1.1 Uptake and Absorption
No reports on the direct uptake and absorption of 2,4,5- and 2,4,6-
trichlorophenol or tetrachlorophenols were found. Kohli, Weisgerber,
and Klein (1976) reported the formation of 2,3,4,6-tetrachlorophenol in
lettuce plants following treatment with lindane (Y-l,2,3,4,5,6-hexachloro-
cyclohexane). Lettuce plants (approximately three weeks old) were planted
in nutrient solution containing li|C-labeled lindane at a level of 1.45
mg/liter. Plants were grown in flasks for four weeks, and at the end of
the treatment both the plants and the nutrient solution were tested for
the presence of lindane and its metabolic products. Of the original
radioactivity, 7.8% was found in the nutrient solution at the end of the
four-week treatment; 1% or less of the 7.8% was present as 2,3,4,6-tetra-
chlorophenol. No conjugates of 2,3,4,6-tetrachlorophenol were detected
in the nutrient solution. Analysis of the plants revealed the presence
of li4C-labeled compounds comprising 14.1% of the original radioactivity
in the nutrient solution. Both 2,3,4,6-tetrachlorophenol and tetrachloro-
phenol conjugates were detected in the plants. Approximately 1% of the
radioactivity found in the plants was identified as free 2,3,4,6-tetra-
chlorophenol, and 3% consisted of tetrachlorophenol conjugates. The
chemical nature of the conjugates was not determined. The metabolic
pathways responsible for the presence of 2,3,4,6-tetrachlorophenol in
plants treated with lindane were not discussed.
C.4.1.2 Transport and Distribution
No information on the transport and distribution of 2,4,5- and
2,4,6-trichlorophenol or tetrachlorophenols was found. The presence of
2,3,4,6-tetrachlorophenol in lettuce plants grown in a nutrient solution
containing lindane (Section C.4.1.1) resulted from uptake of lindane and
its subsequent biodegradation to 2,3,4,6-tetrachlorophenol in the plant
(Kohli, Weisgerber, and Klein, 1976). However, tetrachlorophenol could
possibly have formed in the nutrient solution with subsequent direct
plant uptake. Unfortunately, this study sheds little light on the trans-
port and distribution of 2,3,4,6-tetrachlorophenol in plants.
C.4.1.3 Biotransformation
No information on the biotransformation of 2,4,5- and 2,4,6-tri-
chlorophenol or tetrachlorophenols was found. Kohli, Weisgerber, and
Klein (1976) found 2,3,4,6-tetrachlorophenol conjugates as well as free
2,3,4,6-tetrachlorophenol in lettuce plants (Section C.4.1.1). The nature
of these conjugates and their role in the biodegradation of 2,3,4,6-
tetrachlorophenol are unknown.
182
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183
C.4.1.4 Elimination
No information was found on the elimination of trichlorophenols or
tetrachlorophenols in vascular plants.
C.4.2 EFFECTS
C.4.2.1 Physiological or Biochemical Role
No physiological role or requirement for trichlorophenols or tetra-
chlorophenols in plants has been reported.
C.4.2.2 Toxicity
C.4.2.2.1 Mechanism of Action — No information on the mechanism of
toxicity of trichlorophenols or tetrachlorophenols to vascular plants was
located.
C.4.2.2.2 General Toxicity — Blackman, Parke, and Carton (1955)
determined the concentrations of 2,4,5- and 2,4,6-trichlorophenol and
2,3,4,6-tetrachlorophenol in water which caused "death" in half of the
fronds of the aquatic plant Lerrrna minor. Lernna minor plants were grown
in nutrient solution containing various concentrations of these chloro-
phenols for 48 hr. Plants were grown at pH 5.1 with illumination of 320
ft-c (3520 Ix) and a temperature of 25°C. At the end of the 48-hr treat-
ment, the fronds were removed, washed with distilled water, and trans-
ferred to chlorophenol-free nutrient solution for another 24 hr. At the
end of the treatment the degree of chlorosis was recorded. Injury to
fronds was assessed by assuming that those fronds that were colorless on
move than half of their surfaces were counted as "dead." The concentra-
tion of any chlorophenol which caused "death" in half the fronds was
calculated. These LC50 values for 2,3,4,5-tetrachlorophenol, 2,4,5-tri-
chlorophenol, and 2,4,6-trichlorophenol were calculated as 2.6 x 10" M,
8.4 x 10~6 M, and 3 x 1Q~5 M respectively. Thus, under these experi-
mental conditions, 2,3,4,5-tetrachlorophenol was approximately three
times more toxic to Lernna minor than was 2,4,5-trichlorophenol, and 2,4,5-
trichlorophenol was three times more toxic than 2,4,6-trichlorophenol.
These values were corrected for the effects of dissociation of the com-
pounds at pH 5.1 because the pK values for the compounds vary over a
considerable range. In another study, no effect was seen on Ludvigia sp.
or Anaoharis sp. over an eight-month period in a flow-through bioassay
system at 2,4,6-trichlorophenol concentrations from 0.01 to 4.1 mg/liter
(Manufacturing Chemists Association, 1972).
C.4.2.2.3 Mitotic Effects - Amer and Ali (1974) investigated the
mitotic effect of 2,4,5-trichlorophenol on Vioia faba. Plants were
sprayed daily with 7 ml of aqueous 2,4,5-trichlorophenol solution con-
taining 63 mg trichlorophenol per liter. Flower buds were gathered
either 5 or 25 days following initiation of treatment, and pollen mother
cells were checked for mitotic abnormalities. Abnormalities were not
detected in plants treated with 2,4,5-trichlorophenol, but significant
increases in mitotic abnormalities were seen in plants sprayed with a
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184
solution containing 0.39 mg 2,4-dichlorophenol per liter (Section
B.4.2.2.3). No information regarding possible mitotic effects of
2,4,6-trichlorophenol or tetrachlorophenols was found.
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185
SECTION C.4
REFERENCES
1. Amer, S. M., and E. M. Ali. 1974. Cytological Effects of Pesticides:
V. Effects of Some Herbicides on Vioia fdba. Cytologia 39(4):633-643.
2. Blackman, G. E. , M. H. Parke, and G. Carton. 1955. The Physiological
Activity of Substituted Phenols: I. Relationships between Chemical
Structure and Physiological Activity. Arch. Biochem. Biophys. 54:45-54.
3. Kohli, J. , I. Weisgerber, and W. Klein. 1976. Balance of Conversion
of [ 1'*C]Lindane in Lettuce in Hydroponic Culture. Pestic. Biochem.
Physiol. 6:91-97.
4. Manufacturing Chemists Association. 1972. The Effect of Chlorination
on Selected Organic Chemicals. Water Pollution Control Research Series.
U.S. Environmental Protection Agency, Washington, B.C. pp. 73-100.
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C.5 BIOLOGICAL ASPECTS IN WILD AND DOMESTIC ANIMALS
C.5.1 BIOLOGICAL ASPECTS IN BIRDS AND MAMMALS
Data on the effects of 2,4,5- and 2,4,6-trichlorophenol and tetra-
chlorophenols on mammals primarily involve experimental animals and are
therefore discussed in Section C.6. This section summarizes the effects
of these compounds on wild and domestic mammals.
C.5.1.1 Metabolism
C.5.1.1.1 Uptake and Absorption — No studies have addressed the
direct uptake of higher chlorophenols in birds and domestic mammals.
2,4,5-Trichlorophenol may appear in domestic animals exposed to chemi-
cally similar substances. For example, ronnel [0,0-dimethyl <9-(2,4,5-
trichlorophenyl) phosphorothioate] is an organophosphate used extensively
for the control of cattle grubs and external parasites such as lice,
flies, and ticks. It also is used as a systemic grub control agent and
has been sold in the form of medicated mineral mixtures or concentrates
which are either fed directly or are mixed with feed ingredients (Gehrt,
1972). The chemical structure of ronnel suggests that 2,4,5-trichloro-
phenol may be a metabolic breakdown product in animals, but data are not
available. In addition, the presence of 10% to 20% 2,3,4,6-tetrachloro-
phenol in commercial pentachlorophenol provides a means of direct uptake
of tetrachlorophenol by domestic animals exposed to pentachlorophenol-
treated wood (Section C.5.1.2.2.3).
C.5.1.1.2 Transport and Distribution — 2,4,5-Trichlorophenol has
been detected in cows fed diets containing the herbicide 2,4,5-trichloro-
phenoxyacetic acid (2,4,5-T). Bjerke et al. (1972) studied the appear-
ance of 2,4,5-trichlorophenol in the milk and cream of cows fed diets
containing 2,4,5-T at levels of 10, 30, 100, 300, and 1000 mg/kg of feed.
At the lower dose levels, cows were kept on diets containing 2,4,5-T for
14 days and then returned to normal diets without 2,4,5-T for an addi-
tional 7 days. Cows receiving 2,4,5-T at 1000 mg/kg feed were fed for
21 days, followed by 7 days on normal diets. No 2,4,5-trichlorophenol
was present in the milk or cream of cows fed 2,4,5-T at the 10 or 30
mg/kg level. Demonstrable amounts of 2,4,5-trichlorophenol (as well as
2,4,5-T) were detected in the milk and cream of cows fed 2,4,5-T at
levels of 1000 mg/kg in the feed (Table C.5.1). Average residues of
2,4,5-T and 2,4,5-trichlorophenol in the milk were 0.42 and 0.23 mg/liter
respectively. Average residues in cream were 0.26 mg/liter 2,4,5-T and
0.19 mg/kg 2,4,5-trichlorophenol. Acid hydrolysis of the milk and sub-
sequent residue determination indicated that no conjugation of 2,4,5-
trichlorophenol had occurred. Thus, following 2,4,5-T ingestion, either
2,4,5-T or its metabolite 2,4,5-trichlorophenol must have been trans-
ported for these residues to appear in the milk. No other data on the
transport and distribution of higher chlorophenols in birds or mammals
are available.
186
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TABLE C.5.1. RESIDUES OF 2,4,5-T AND 2,4,5-TRICHLOROPHENOL IN MILK AND CREAM FROM COWS FED 2,4,5-T
2,4,5-T T^e
in diet £
(mg/kg feed) (dayg)
100 2
5
9
10
11
12
300 2
5
9
10
11
1000 2
5
9
12
16
17
18
19
20
Oa 1
3
5
7
Residues of 2,4,5-T
(ug/liter)
Cow No.
36
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
0.08
<0.05
0.05
0.06
<0.05
0.31
0.44
0.42
0.37
0.23
0.33
0.49
0.33
0.23
0.07
<0.05
<0.05
<0.05
Cow No.
7417
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
0.08
<0.05
0.06
0.07
0.05
0.26
0.27
0.32
0.30
0.36
0.28
0.29
0.40
0.28
0.12
<0.05
<0.05
<0.05
Cow No.
30
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
0.20
0.08
0.28
0.31
0.13
0.78
0.54
0.44
0.29
1.0
0.75
0.38
0.35
0.32
0.12
<0.05
<0.05
<0.05
Cream
composite
<0.05
<0.05
0.10
0.08
<0.05
0.41
0.25
0.17
0.27
0.21
<0.05
Residues of 2,4,5-trichlorophenol
(yg/liter)
Cow No.
36
0.06
0.05
0.08
0.09
0.16
0.17
0.15
0.18
0.15
0.09
<0.05
<0.05
<0.05
Cow No.
7417
0.05
0.07
0.12
0.13
0.37
0.21
0.31
0.23
0.23
0.22
<0.05
<0.05
<0.05
Cow No.
30
<0.05
<0.05
<0.05
0.16
0.39
0.22
0.23
0.21
0.25
0.13
<0.05
<0.05
<0.05
Cream
composite
0.05
0.06
0.09
0.10
0.12
0.21
0.17
0.20
0.20
0.18
<0.05
"Animals fed diets containing 1000 mg 2,4,5-T per kilogram feed for 21 days followed by a 7-day withdrawal
period on 2,4,5-T-free diets.
Source: Adapted from Bjerke et al., 1972, Table III, p. 965. Reprinted by permission of the publisher.
oo
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188
C.5.1.1.3 Biotransformation — No reports were found on the bio-
transformation of trichlorophenols or tetrachlorophenols in wild and
domestic animals.
C.5.1.1.A Elimination — The available literature did not discuss
the elimination of trichlorophenols and tetrachlorophenols in wild and
domestic animals.
C.5.1.2 Effects
C.5.1.2.1 Physiological or Biochemical Role — No information sug-
gested that 2,4,5- and 2,4,6-trichlorophenol or tetrachlorophenols play
any normal physiological role in birds or domestic animals.
C.5.1.2.2 Toxicity
C.5.1.2.2.1 Mechanisms of action — No reports discussed the mech-
anisms of action of these higher chlorophenols in birds or mammals.
C.5.1.2.2.2 General toxicity — Toxic effects of 2,4,5- and 2,4,6-
trichlorophenol and tetrachlorophenols in birds or domestic animals have
not been documented. Anderson et al. (1949) studied the effect of 2,4,5-
trichlorophenol on cattle. Steers ranging in weight from 360 to 630 Ib
(163 to 284 kg) were fed diets containing the zinc salt of 2,4,5-tri-
chlorophenol. Animals were given daily doses of either 18 mg/kg or 159
mg/kg for 78 days or 53 mg/kg for 154 days. No effect was seen on packed
blood cell volume, nor was hemoglobin affected by the treatments. No
abnormalities were noted in the organs or other tissues of slaughtered
animals, and the percent gain in weight and in feed consumption was
approximately the same in the treated animals as in the controls.
C.5.1.2.2.3 Musty taint — An economically important problem has
recently surfaced in the broiler chicken industry in England — the pres-
ence of musty taint in chickens and their eggs. Curtis et al. (1972,
1974) found that this musty taint is caused by 2,3,4,6-tetrachloroanisole
and pentachloroanisole in broiler chickens. The primary source of musty
taint appears to be 2,3,4,6-tetrachloroanisole. Substantial quantities
of anisoles are found in wood shavings used as bedding materials in the
chicken cages. Anisoles apparently are formed in the litter as a result
of methylation of the parent chlorophenols by fungi present in the litter.
Pentachlorophenol and 2,3,4,6-tetrachlorophenol are extensively applied
to freshly sawn lumber as antifungal agents. Curtis et al. (1972) detected
up to 100 mg 2,3,4,6-tetrachlorophenol per kilogram of wood in several
samples of shavings and sawdust produced from imported timber. Parr et
al. (1974) surveyed fresh shavings from 32 commercial broiler houses for
the presence of 2,3,4,6-tetrachlorophenol and found levels of 4 to 307 mg
2,3,4,6-tetrachlorophenol per kilogram wood shavings. Pentachlorophenol
is a more widely used wood preservative than 2,3,4,6-tetrachlorophenol;
however, technical grade pentachlorophenol contains 10% to 20% 2,3,4,6-
tetrachlorophenol, and therefore, routine treatment of timber with penta-
chlorophenol as a wood preservative might include inadvertent application
of 2,3,4,6-tetrachlorophenol. Also, dechlorination of pentachlorophenol
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189
yields tetrachlorophenols in wood chips and shavings. The mode of entry
of anisoles into the chickens has not been established. It seems likely,
however, that the anisoles, and not the parent chlorophenols, are taken
up directly by the chickens. Curtis et al. (1972) conducted simulated
litter experiments in which a small inoculum of tainted litter was incu-
bated with sawdust, 2,3,4,6-tetrachlorophenol, and pentachlorophenol.
Virtually quantitative conversion of 2,3,4,6-tetrachlorophenol to the
anisole occurred within nine days (Figure C.5.1).
ORNL-DWG 78-10503
O 2,3,4,6-TETRACHLOROPHENOL
• 2,3,4,6-TETRACHLOROANISOLE
A 2,3,4,6-TETRACHLOROANISOLE IN
AUTOCLAVED SYSTEM
2,3,4,6-TETRACHLOROANISOLE IN
SYSTEM WITHOUT INOCULUM
10 20
INCUBATION TIME (days)
Figure C.5.1. Conversion of 2,3,4,6-tetrachlorophenol to 2,3,4,6-
tetrachloroanisole in simulated broiler house litter. Source: Adapted
from Curtis et al., 1972, Figure 1, p. 224. Reprinted by permission of
the publisher.
The presence of 2,.4,6-trichlorophenol and 2,4,6-trichloroanisole in
extracts of broiler house litter has been reported by Land et al. (1975).
Although these compounds were present in relatively small amounts, their
contribution to the musty taint problem cannot be ignored. In experi-
ments conducted by Land et al. (1975), pure cultures of fungi isolated
from broiler house litter were capable of methylating 2,4,6-tncnloro-
phenol to the corresponding chloroanisole. Furthermore, it was clearly
-------
190
demonstrated that a musty taint could be achieved in broiler chickens in
the presence of 2,4,6-trichloroanisole. 2,4,6-Trichlorophenol in broiler
litter may result from its presence in wood preservatives (Land et al.,
1975), from the breakdown of pentachlorophenol (Land et al., 1975), or
from disinfectants used in chicken houses (Orr et al., 1975).
C.5.2 BIOLOGICAL ASPECTS IN FISH AND OTHER AQUATIC ORGANISMS
C.5.2.1 Metabolism
C.5.2.1.1 Uptake and Absorption — A report by the Manufacturing
Chemists Association (1972) indicated that 2,4,6-trichlorophenol may be
toxic to fish; therefore, absorption of the compound by fish can be
inferred. However, no information relating to uptake and absorption of
higher chlorophenols was found.
C.5.2.1.2 Transport and Distribution — No information on transport
and distribution of trichlorophenols and tetrachlorophenols in aquatic
organisms was located.
C.5.2.1.3 Biotransformation — Data on the biotransformation of
trichlorophenols and tetrachlorophenols in aquatic organisms were not
available in the literature.
C.5.2.1.4 Elimination — No reports discussed the elimination of
trichlorophenols and tetrachlorophenols in aquatic organisms.
C.5.2.2 Effects
C.5.2.2.1 Physiological or Biochemical Role — No evidence suggests
that 2,4,5- and 2,4,6-trichlorophenol or tetrachlorophenols perform any
normal physiological function in aquatic organisms.
C.5.2.2.2 Toxicity
C.5.2.2.2.1 Mechanisms of action — No data dealing specifically
with the mechanism of action of trichlorophenols and tetrachlorophenols
in aquatic organisms were reported. The mechanism of action of these
compounds in higher organisms is discussed in Section C.6.2. The appli-
cability of this information to aquatic organisms is unknown.
C.5.2.2.2.2 General toxicity — No information on the toxicity of
2,4,5-trichlorophenol or tetrachlorophenols in aquatic organisms was
found, but studies of 2,4,6-trichlorophenol toxicity were reported. The
toxicity of 2,4,6-trichlorophenol to the fathead minnow (Pimephales
promelas) has been studied (Manufacturing Chemists Association, 1972).
Static bioassays determined that the 96-hr median tolerance limit of
fathead minnows to 2,4,6-trichlorophenol was 0.6 mg/liter. Complete
mortality of fish cultured at 2,4,6-trichlorophenol concentrations of
10 mg/liter occurred within 24 hr. Fish mortality was determined at
three concentrations (1, 10, and 100 mg/liter). Because 100% mortality
occurred at the two higher concentrations, extrapolation from two points
-------
191
was used in the calculation of the LCSO value. The validity of the
determination is therefore questionable. The investigators also studied
the toxic effects of 2,4,6-trichlorophenol on fish, microflora, and micro-
fauna in aquaria with flow-through water systems. No significant effect
on fish was seen when 2,4,6-trichlorophenol was added at a dosage of 0.06
or 0.47 mg/liter. The authors suggested that the tolerance of fish to'
these relatively high levels of 2,4,6-trichlorophenol indicated either a
greater resistance of the fish in a more natural environment or degrada-
tion or assimilation of the compounds within the aquaria. Spectrophoto-
metric measurement of 2,4,6-trichlorophenol content in the aquaria was
performed (Table C.5.2). The 2,4,6-trichlorophenol residues determined
by this method were lower than the applied dose. It is obviously dif-
ficult to draw conclusions from this type of data because measured values
of 2,4,6-trichlorophenol in the static bioassays were not reported. When
2,4,6-trichlorophenol was added at an initial level of 4.15 mg/liter, all
the test fish died within a few days. Because the control fish in the
flow-through bioassay systems suffered a high mortality rate over the
experimental period, it is difficult to evaluate these findings.
TABLE C.5.2. APPLIED VERSUS
MEASURED CONCENTRATIONS OF
2,4,6-TRICHLOROPHENOL IN A
FLOW-THROUGH BIOASSAY SYSTEM
2,4,6-Trichlorophenol
concentration
(mg/liter)
Applied Measured
0.06 Not detectable
0.47 0.25
4.15 1.75
Source: Adapted from Man-
ufacturing Chemists Association,
1972, Table 16, p. 85.
Aquatic microfauna were also examined for 2,4,6-trichlorophenol in
the flow-through bioassay system (Manufacturing Chemists Association,
1972). Although the instability of the control microorganisms in this
study prevent a valid statistical treatment of the data, an inhibitory
effect of 2,4,6-trichlorophenol on total numbers of microorganisms -
particularly on the population of stalked ciliates - was indicated at
2,4,6-trichlorophenol concentrations greater than 4 mg/liter. Thus,
-------
192
qualitative information was gathered in these experiments, but the flow-
through studies did not provide reliable quantitative data from which
conclusive determinations of toxicity could be made.
Clowes (1951) reported that 2,4,6-trichlorophenol affected oxygen
consumption and cell division in fertilized sea urchin eggs (Arbacia
punctulata). Sea urchin eggs treated with 6.2 mg/liter 2,4,6-trichloro-
phenol consumed approximately twice as much oxygen as control eggs, and
this phenomenon was accompanied by a dramatic decrease in the rate of
cell division. At the limiting concentration of 6.2 mg/liter, a decreased
rate of cell division was initiated in treated eggs; at a concentration of
39 mg/liter, cell division ceased entirely.
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193
SECTION C.5
REFERENCES
1. Anderson, G. W., C. H. Arndt, E. G. Godbey, and J. C. Jones. 1949.
Cattle-Feeding Trials with Derivatives of 2,4,5-Trichlorophenol. J.
Am. Vet. Med. Assoc. 115:121-123.
2. Bjerke, E. L., J. L. Herman, P. W. Miller, and J. H. Wetters. 1972.
Residue Study of Phenoxy Herbicides in Milk and Cream. J. Agric.
Food Chem. 20(5):963-967.
3. Clowes, G.H.A. 1951. The Inhibition of Cell Division by Substituted
Phenols with Special Reference to the Metabolism of Dividing Cells.
Ann. N.Y. Acad. Sci. 51:1409-1431.
4. Curtis, R. F., C. Dennis, J. M. Gee, M. G. Gee, N. M. Griffiths,
D. G. Land, J. L. Peel, and D. Robinson. 1974. Chloroanisoles as
a Cause of Musty Taint in Chickens and Their Microbiological Forma-
tion from Chlorophenols in Broiler House Litters. J. Sci. Food
Agric. 25:811-828.
5. Curtis, R. F., D. G. Land, N. M. Griffiths, M. Gee, D. Robinson,
J. L. Peel, C. Dennis, and J. M. Gee. 1972. 2,3,4,6-Tetrachloro-
anisole Association with Musty Taint in Chickens and Microbiological
Formation. Nature (London) 235:223-224.
6. Gehrt, A. J. 1972. Drugs in Feeds: Methods for Determining Ronnel
in Feeds and Mineral Mixtures. J. Assoc. Off. Anal. Chem. 55(4):
710-713.
7. Land, D. G., M. G. Gee, J. M. Gee, and C. A. Spinks. 1975. 2,4,6-
Trichloroanisole in Broiler House Litter: A Further Cause of Musty
Taint in Chickens. J. Sci. Food Agric. 26(10): 1585-1591.
8. Manufacturing Chemists Association. 1972. The Effect of Chlorina-
tion on Selected Organic Chemicals. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C. pp.
73-100.
9. Orr, H. L., J. P. Walker, G. W. Friars, and N. A. Fish. 1975. Chem-
ical Sanitizer Influences on the Flavor of Chicken Broilers. Poult.
Sci. 54(4):1031-1035.
10. Parr, L. J., M. G. Gee, D. G. Land, D. Robinson, and R. F. Curtis.
1974. Chlorophenols from Wood Preservatives in Broiler House Litter.
J. Sci. Food Agric. 25:835-841.
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C.6 BIOLOGICAL ASPECTS IN HUMANS
Many commonly used organochlorine compounds decompose in mammals
to yield higher chlorophenols. In many cases, the only available infor-
mation on the biological aspects of these chlorophenols in mammals is
derived from studies dealing with this process. Although this information
is indirect, it is currently the best available source. Data relating
to organochlorine degradation to form higher chlorophenols are summarized
in Table C.6.1. This information is useful not only in inferring some of
the biological aspects of the chlorophenols, but also in indicating a
possible source of exposure to higher chlorophenols for humans and other
mammals.
Chemical nomenclature in studies involving organochlorine compounds
must be carefully examined because common names for some of these chemi-
cals may be confusing and misleading. For example, certain hexachloro-
cyclohexane isomers have been used as insecticides. Hexachlorocyclohexane
may exist in four isomeric forms: alpha, beta, gamma, and delta. Lindane
is the common name for Y-l,2,3,4,5,6-hexachlorocyclohexane, although lin-
dane preparations may contain small amounts of the alpha, beta, and delta
isomers. A commonly used (although incorrect) name for hexachlorocyclo-
hexane is benzene hexachloride. Chlorobenzene compounds (which do contain
an aromatic nucleus) are widely used; therefore, caution is required in
reading the literature to avoid confusing benzene hexachloride (hexa-
chlorocyclohexane) with hexachlorobenzene. In this report, hexachloro-
cyclohexane has been substituted whenever the original investigators
used the common name benzene hexachloride.
C.6.1 METABOLISM
C.6.1.1 Uptake and Absorption
Toxicity data derived from experimental animals indicate that 2,4,5-
and 2,4,6-trichlorophenol are absorbed readily from the gastroenteric
tract and from parenteral sites of injection. Both trichlorophenol iso-
mers can produce redness and edema on skin contact and, on prolonged ex-
posure, may produce mild to moderate chemical burns of the skin. Contact
with the eye induces conjunctival irritation and sometimes corneal injury
and iritis (Dow Chemical Company, 1969; Gosselin et al., 1976). McCollister
Lockwood, and Rowe (1961) stated, "There is no danger of poisoning from
absorption (of 2,4,5-trichlorophenol) through the skin." 2,4,5-Trichlo-
rophenol and 2,4,6-trichlorophenol apparently do not penetrate intact
rabbit or guinea pig skin (Gosselin et al., 1976). No information on
the rates of absorption of 2,4,5- or 2,4,6-trichlorophenol in humans or
experimental animals was found.
Toxicity data indicate that 2,3,4,6-tetrachlorophenol is also readily
absorbed from the gastroenteric tract and from parenteral sites of injec-
tion. Furthermore, 2,3,4,6-tetrachlorophenol dissolved in organic solvents
may be absorbed directly through the skin in acutely toxic amounts (Gosselin
et al., 1976). No studies of the uptake of 2,3,5,6-tetrachlorophenol in
194
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TABLE C.6.1. CHLOROPHENOLS DETECTED IN ANIMAL TISSUE OR EXCRETION FOLLOWING ADMINISTRATION OF RELATED ORGANIC COMPOUNDS
Compound administered
2,4,5-T (2,4,5-trichlorophenoxyacetic acid)
Silvex [2-(2,4,5-trichlorophenoxy)propionic acid]
ct-Hexachlorocyclohexane
8-Hexachlorocyclohexane
Lindane (y-hexachlorocyclohexane)
B-Hexachlorocyclohexane
Lindane (y-hexaehlorocyclohexane)
6-Hexachlorocyclohexane
4- (2 ,4 ,5-Trichlorophenoxy) butyric acid
Y-2 ,3,4,5, 6-Pentachlorocy clohex-1-ene
Ronnel [0,0-dimethyl 0-(2,4,5-trichlorophenyl)
phosphorothioate]
Erbon [2-(2,4,5-trichlorophenoxy)ethyl 2,2-
d ichloropropionate ]
Pentachlorobenzene
Animal
Sheep
Cow
Sheep
Cattle
Rat
Rat
Rat
Rat
Mouse
Mouse
Rat
Rat
Rat
Rat
Rat
Rat
Sheep
Rat
Chlorophenol detected
2,4, 5-Tr ichlorophenol
2,4, 5-Tr ichlorophenol
2,4, 5-Trichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Tr ichlorophenol
2,4, 5-Trichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Tr ichlorophenol
2,4, 6-Tr ichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2,3,4, 5-Tetrachlorophenol
2,3,4, 6-Te trachlorophenol
2,4, 6-Trichlorophenol
2,4, 6-Trichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2,3,4, 6-Te trachlorophenol
2,3,5, 6-Tetrachlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2,4, 5-Trichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2, 3, 4, 6-Tetrachlorophenol
2, 3, 5, 6-Tetrachlorophenol
2,4, 5-Trichlorophenol
2,4, 5-Trichlorophenol
2,4, 6-Trichlorophenol
2,3,4, 5-Tetrachlorophenol
2,3,4, 6-Tetrachlorophenol
2, 3, 5, 6-Te trachlorophenol
Source
Clark et al., 1975
Bjerke et al. , 1972
Clark et al. , 1975
Clark et al. , 1975
Koransky et al., 1975
Freal and Chadwick, 1973
Freal and Chadwick, 1973
Chadwick and Freal, 1972
Kurihara and Nakajima, 1974
Kurihara and Nakajima, 1974
Engst et al. , 1976
Freal and Chadwick, 1973
Bo'hme and Grunow, 1974
Freal and Chadwick, 1973
Engst et al. , 1976
Shafik, Sullivan, and Enos ,
1973
Wright et al . , 1970
Engst et al. , 1976
Cn
(cont inued)
-------
TABLE C.6.1 (continued)
Compound administered
Animal
Chlorophenol detected
Source
1,2,4-Trichlorobenzene
1,3,5-Trichlorobenzene
1,2,3,4-Tetrachlorobenzene
1,2,3,5-Tetrachlorobenzene
1,2,4,5-Tetrachlorobenzene
Rabbit 2,4,5-Trichlorophenol
Rabbit 2,4,6-Trichlorophenol
Rabbit 2,3,4,5-Tetrachlorophenol
2,3,4,6-Tetrachlorophenol
Rabbit 2,3,4,5-Tetrachlorophenol
2,3,5,6-Tetrachlorophenol
2,3,4,6-Tetrachlorophenol
Rabbit 2,3,5,6-Tetrachlorophenol
2,3,4,5-Tetrachlorophenol
Kohli, Jones, and Safe, 1976
Kohli, Jones, and Safe, 1976
Kohli, Jones, and Safe, 1976
Kohli, Jones, and Safe, 1976
Kohli, Jones, and Safe, 1976
vo
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197
humans or experimental animals were located. Christensen and Luginbyhl
(1975) reported that 2,3,5,6-tetrachlorophenol is lethal to mice follow-
ing intraperitoneal injection. No other data relating to the rate or
mechanisms of uptake of tetrachlorophenols were reported.
C.6.1.2 Transport and Distribution
Information on the transport and distribution of higher chlorophenols
following their administration to experimental animals or humans is not
available. These chlorophenols, however, have been detected in the tissues
of animals dosed with chemically similar compounds.
Clark et al. (1975) determined the tissue distribution of 2,4,5-
trichlorophenol in sheep fed 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)
at a level of 2000 mg/kg feed. On the basis that each animal ingested a
daily ration of 3% of its body weight, this level represented 60 mg
2,4,5-T per kilogram body weight daily. The animals were maintained on
a diet containing 2,4,5-T for 28 days, and tissue samples were analyzed
for 2,4,5-T and 2,4,5-trichlorophenol residues at the end of this period
(Table C.6.2). 2,4,5-Trichlorophenol was not detected in the fat, but
the liver, kidney, and muscle contained substantial levels of 2,4,5-
trichlorophenol. Withdrawal from 2,4,5-T treatment for one week before
the sheep were killed resulted in a significant reduction in the residue
level in muscle, but the liver and kidney tissues retained most of the
2,4,5-trichlorophenol that had accumulated. Because 2,4,5-T is probably
detoxified in the liver following administration and the compound or its
TABLE C.6.2. RESIDUES OF 2,4,5-T AND
2,4,5-TRICHLOROPHENOL IN SHEEP FED 60 mg/kg
2,4,5-T DAILY FOR 28 DAYS
2,4,5-T residue level
(mg/kg body wt)
2,4,5-Trichlorophenol
residue level
(mg/kg body wt)
Tissue
Muscle
Fat
Liver
Kidney
28-day
exposure
1.00
0.27
2.29
27.2
28-day
exposure
plus 7-day
withdrawal
<0.05
<0.05
<0.05
0.06
28-day
exposure
0.13
<0.05
6.1
0.90
28-day
exposure
plus 7-day
withdrawal
0.05
<0.05
4.4
0.81
Source: Adapted from Clark et al., 1975, Table IV,
p. 576. Reprinted by permission of the publisher.
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198
metabolites are excreted by the kidney, high levels of 2,4,5-trichloro-
phenol in these tissues are not surprising. However, it is difficult to
draw conclusions from these data regarding the fate of 2,4,5-trichloro-
phenol administered directly.
Engst et al. (1976) detected substantial levels of higher chlorophe-
nols in rats dosed with lindane (Y-l,2,3,4,5,6-hexachlorocyclohexane). The
rats received daily doses of 8 mg/kg body weight for 19 consecutive days.
Analysis of tissues for chlorophenol residues revealed the presence of
2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol in the heart. 2,3,4,6-
Tetrachlorophenol and 2,3,5,6-tetrachlorophenol were detected in the liver,
and the kidney contained detectable amounts of 2,4,6-trichlorophenol and
the two tetrachlorophenol isomers. Quantitative residue levels were not
reported, and other rat tissues were not analyzed.
Engst et al. (1976) also detected chlorophenols as metabolites in
rats administered pentachlorophenol, pentachlorobenzene, and y-2,3,4,5,6-
pentachlorocyclohex-1-ene. These compounds are potential metabolites of
lindane and thus may represent intermediate steps in the production of
chlorophenols from lindane. Following administration of pentachlorophenol,
2,3,4,5-, 2,3,4,6-, and 2,3,5,6-tetrachlorophenol were detected in the
urine. 2,4,6-Trichlorophenol and 2,3,4,5-, 2,3,4,6-, and 2,3,5,6-tetra-
chlorophenol were found in the urine of rats dosed with pentachlorobenzene.
2,3,4,5-Tetrachlorophenol were also present in the kidney and the blood.
Metabolites of Y-2,3,4,5,6-pentachlorocyclohex-l-ene and 2,3,4,6- and
2,3,5,6-tetrachlorophenol.
C.6.1.3 Biotransformation
No studies on the metabolic fate of 2,4,5- and 2,4,6-trichlorophenol
or tetrachlorophenols in humans or experimental animals have been conducted,
but some information on metabolic pathways can be derived from other types
of experiments. Kurihara and Nakajima (1974) studied the metabolites of
y- and 3-hexachlorocyclohexane following injection into mice. 2,4,6-
Trichlorophenol was a major metabolite, comprising 25% of the total urinary
metabolites of the two hexachlorocyclohexanes. Most of the 2,4,6-trichlo-
rophenol excreted in the urine was present as conjugates of glucuronide
and sulfate. Very little free 2,4,6-trichlorophenol was detected in the
urine. Following injection of y-hexachlorocyclohexane, 80% of the 2,4,6-
trichlorophenol was excreted as sulfate conjugates, and glucuronide con-
jugates accounted for nearly 20% of the excreted 2,4,6-trichlorophenol.
Following injection of $-hexachlorocyclohexane, sulfate and glucuronide
conjugates of 2,4,6-trichlorophenol comprised 40% and 60%, respectively,
of the 2,4,6-trichlorophenol excreted. Trace amounts of 2,4,5-trichloro-
phenol and its conjugates were also detected in the urine of mice dosed
with 3-hexachlorocyclohexane.
The experimental data obtained by Kurihara and Nakajima (1974) have
been confirmed by Koransky et al. (1975) in experiments with rats. These
investigators injected llfC-labeled a-hexachlorocyclohexane intraperito-
neally. The major urinary metabolites of a-hexachlorocyclohexane were
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199
2,4,6-trichlorophenol and its conjugates. Of the total radioactivity in
the urine, 3% was free 2,4,6-trichlorophenol, and nearly 40% of the total
urinary activity was 2,4,6-trichlorophenol conjugates. The authors pos-
tulated that these conjugates were largely sulfate and glucuronide com-
pounds. Small amounts of 2,4,5-trichlorophenol (<0.05% of the total
urinary activity) and even smaller amounts of 2,3,4,5-tetrachlorophenol
were also detected in the urine. The amounts of 2,4,5-trichlorophenol
and 2,3,4,5-tetrachlorophenol present in conjugated forms were not
determined.
Bbhrne and Grunow (1974) detected both free and conjugated 2,4,5-
trichlorophenol in the urine of rats after administering the herbicide
4-(2,4,5-trichlorophenoxy)butyric acid. Free 2,4,5-trichlorophenol was
also detected in the feces. Following administration of lindane to rats,
Engst et al. (1976) found 2,4,6-trichlorophenol and 2,3,4,6- and 2,3,5,6-
tetrachlorophenol in the urine. When pentachlorophenol was administered,
2,3,4,5-, 2,3,4,6-, and 2,3,5,6-tetrachlorophenol were detected as metab-
olites in the urine. To a small extent (no quantitative data were fur-
nished), each of the four metabolites was conjugated with 3-glucuronide.
Thus, evidence exists that higher chlorophenols are excreted in a
conjugated form in the urine of animals. The metabolic pathway respon-
sible for this conjugation is not known, and other metabolic pathways
which may be operative in humans and other mammals following ingestion
of chlorophenols or their precursors remain speculative.
C.6.1.4 Elimination
No information was found on the elimination of 2,4,5- and 2,4,6-
trichlorophenol or the tetrachlorophenol isomers following direct admin-
istration of these compounds to humans or experimental animals. Data
reported by Engst et al. (1976), Kurihara and Nakajima (1974), and Bohme
and Grunow (1974), which were discussed in detail in Section C.6.1.3 dem-
onstrate that chlorophenols formed as metabolites of other organochlorine
compounds are frequently excreted in the urine in the conjugated form.
Evidence exists (Kurihara and Nakajima, 1974) that 2,4,6-trichlorophenol
formed following administration or y- or 3-1,2,3,4,5,6-hexachlorocyclo-
hexane is excreted largely as glucuronide and/or sulfate conjugates.
Other investigations have confirmed that 2,4,6-trichlorophenol is excreted
primarily as a conjugate in experimental animals (BShme and Grunow, 1974;
Koransky et al., 1975). Evidence also indicates that 2,4,5-trichlorophenol
and 2,3,4,5-, 2,3,4,6-, and 2,3,5,6-tetrachlorophenol are excreted as
conjugates, primarily of glucuronic acid (BBhme and Grunow, 1974; Engst,
1976). It is not clear whether these compounds are excreted in experi-
mental animals primarily as conjugates or in the free form; however, the
presence of conjugates has been confirmed. Higher chlorophenols have
not been detected in fecal material following administration of organ-
ochlorine compounds; therefore, the urinary route is most likely the
primary route of elimination.
It is extremely difficult to extrapolate from excretion rate data
taken from experiments in which the chlorophenol in question is derived
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200
from an organochlorine precursor compound. The precursor itself may be
in various deposits in the body of the animal or human; thus, excretion
rates will depend primarily on the lability of the precursor compound and
not on any inherent characteristic of the chlorophenol. Furthermore,
urinary pH interrelationships with pKa values for different chlorophenols
could be quantitatively important in urinary excretion. The data of
Chadwick and Freal (1972) indicated that following a one-week exposure
to lindane, rats excreted 2,4,5- and 2,4,6-trichlorophenol and 2,3,4,5-
and 2,3,4,6-tetrachlorophenol for at least one month following treatment.
Shafik, Sullivan, and Enos (1973) administered ronnel [0,0-dimethyl 0-
(2,4,5-trichlorophenyl) phosphorothioate] to rats at a dosage of 234 nan-
omoles and found that 2,4,5-trichlorophenol produced in the animal was
totally excreted in two days. The difference in excretion rates in the
two studies likely depends on the chemical nature of the precursor. Clark
et al. (1975) reported that after 2,4,5-T was administered to sheep, resi-
dues of 2,4,5-trichlorophenol in the liver and kidney remained relatively
constant for one week after dosing was stopped. However, the 2,4,5-
trichlorophenol content of the muscle dropped by a factor of 3 during
the same one-week withdrawal period.
C.6.2 EFFECTS
C.6.2.1 Physiological or Biochemical Role
There is no evidence that 2,4,5- and 2,4,6-trichlorophenol or tetra-
chlorophenol isomers have any normal biochemical or physiological role
in humans or other mammals.
C.6.2.2 Toxicity
C.6.2.2.1 Mechanism of Action — Human systemic poisonings by 2,4,5-
and 2,4,6-trichlorophenol or tetrachlorophenols have not been reported.
Investigations with experimental animals have indicated that 2,4,5- and
2,4,6-trichlorophenol and 2,3,4,6- and 2,3,5,6-tetrachlorophenol are capa-
ble of causing death. Lethal dosages and routes of administration for
these compounds are compiled in Table A.6.4. The mechanism of toxicity
has not been studied adequately. In general, trichlorophenols and tetra-
chlorophenols possess the ability to uncouple oxidative phosphorylation in
higher animals. 2,4,6-Trichlorophenol has a convulsive action in experi-
mental animals as well as an ability to uncouple oxidative phosphorylation.
These mechanisms may explain all or part of the toxic capacity of these
compounds. This question warrants further research.
According to Mitsuda, Murakami, and Kawai (1963), 2,4,5- and 2,4,6-
trichlorophenol and 2,3,4,6-tetrachlorophenol are capable of inhibiting
oxidative phosphorylation in rat liver mitochondria. 2,3,4,6-Tetrachlo-
rophenol was the most active of the three compounds in inhibiting oxidative
phosphorylation. Its activity was approximately 50% of the activity of
pentachlorophenol; trichlorophenol was less active in inhibiting oxidative
phosphorylation. 2,4,5-Trichlorophenol possessed approximately 30% of
the activity of pentachlorophenol, and 2,4,6-trichlorophenol possessed 5%
of the activity of pentachlorophenol. Farquharson, Gage, and Northover
-------
201
(1958) examined the capacity of these compounds to inhibit oxidative phos-
phorylation in rat brain homogenate preparations and also their effects
on the isolated rat diaphragm. Relatively low concentrations of each of
the compounds tested (2,4,5- and 2,4,6-trichlorophenol and 2,3,4,6-tetra-
chlorophenol) stimulated oxygen consumption in rat brain homogenates.
Effective concentrations were very close to those for pentachlorophenol -
a well known uncoupler of oxidative phosphorylation. Each of the higher
chlorophenols mentioned, as well as pentachlorophenol, were capable of
sending the isolated rat diaphragm into contracture. Trichlorophenols and
tetrachlorophenols have also been reported to selectively inhibit cytochrome
P-450 (Arrhenius et al., 1977).
Typical clinical signs of pentachlorophenol poisoning in experimental
animals include hyperpyrexia and extremely rapid onset of rigor mortis
following death. Rapid, intense onset of rigor mortis occurred within 3
to 5 min after death when pentachlorophenol, 2,3,4,6-tetrachlorophenol,
and 2,4,6- and 2,4,5-trichlorophenol were injected (Farquharson, Gage,
and Northover, 1958). Hyperpyrexia appeared with injection of 2,3,4,6-
tetrachlorophenol in rats; 2,4,5- and 2,4,6-trichlorophenol poisoning
was characterized by a slight elevation in body temperature. Although
the correspondence between poisoning by pentachlorophenol and poisoning
by trichlorophenols and tetrachlorophenols is not exact, there is suf-
ficient evidence that the primary toxic mechanism of these compounds in
experimental animals is inhibition of oxidative phosphorylation, thereby
short-circuiting metabolism. A general property of uncouplers is the
ability to inhibit the enzymes lactate dehydrogenase and hexokinase in
in vitro systems. 2,4,6-Trichlorophenol and 2,3,4,6-tetrachlorophenol
inhibit these enzymes in in vitro systems (Stockdale and Selwyn, 1971).
C.6.2.2.2 General Toxicity - The toxicological picture of trichlo-
rophenols or tetrachlorophenols in experimental animals is not well docu-
mented. Because human systemic intoxication has not been reported, the
toxicological picture in humans remains speculative.
Farquharson, Gage, and Northover (1958) studied the toxicology of
12 chlorophenol isomers in the rat. They separated the chlorophenols
which they tested into two general categories: convulsive agents and
nonconvulsive agents. Injection of phenol and the convulsive phenols,
including 2,4,6-trichlorophenol, resulted in a similar syndrome. The
animals experienced tremors in 40 to 120 sec following dosing, and these
tremors became generalized almost immediately. The head and forepaws
were sometimes affected first. When poisoning was sufficiently great for
the tremors to increase in severity, intermittent convulsions were seen
and the rat usually fell on its side with a loss of righting reflexes.
Coma and dyspnea followed, and the rats generally lay prostrate until
death. Treatment with nonconvulsive chlorophenols, including 2,4,5-
trichlorophenol and 2,3,4,6-tetrachlorophenol, produced a slightly dif-
ferent toxicological picture. Hypotonia was pronounced, beginning in
the hind limb within 2 to 3 min, and generally progressed to involve
forelimbs and neck so that the rat was completely prostrate. Eventually,
the eye reflex weakened and no withdrawal response to toe pinching was
seen. There was a marked rise in temperature following injection of
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202
2,3,4,6-tetrachlorophenol, but 2,4,6-trichlorophenol caused only a slight
elevation in temperature. In all animals treated with chlorophenols,
respiration was initially accelerated but then became slower as coma
developed, particularly in the case of 2,3,4,6-tetrachlorophenol. 2,3,4,6-
Tetrachlorophenol poisoning is unique in one other respect. Respiration
ceased 0.5 to 2 min before the heart stopped beating, but with the other
compounds, respiration ceased either just before or simultaneously with
heart stoppage. Pronounced and rapid rigor mortis occurred with 2,4,5-
and 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol. Other effects
noted intermittently in poisoned animals included chromodacryorrhea,
lacrimation, salivation, and diarrhea.
McCollister, Lockwood, and Rowe (1961) studied the toxicological
effect of 2,4,5-trichlorophenol in rats and rabbits. In rats given acute
oral doses of 2,4,5-trichlorophenol, the primary symptom was diarrhea.
Rabbits were fed 20 oral doses of 2,4,5-trichlorophenol by intubation in
a 28-day period. Toxicological examination showed no changes when the
animals received doses of either 1 or 10 mg/kg. Very slight kidney changes
were seen at 100 mg/kg, and very slight kidney and liver changes were
noted at doses of 500 mg/kg. Rats were maintained on diets containing
2,4,5-trichlorophenol so that doses in the food resulted in a daily intake
of 10, 30, 100, 300, or 1000 mg/kg body weight. No adverse effects were
observed in the rats given 10, 30, or 100 mg/kg daily. Gross appearance
and behavior, mortality, food consumption, growth, hematologic values,
final average body and organ rate ratios, and gross microscopic examina-
tion of the tissues were assessed. Rats receiving 300 mg/kg or 1000
mg/kg daily sustained minor microscopic damage to the kidneys or liver.
The kidneys showed a moderate degenerative change in the epithelium of
the convoluted tubules and early proliferation of the interstitial tissue.
Liver damage included mild centrilobular degenerative changes. Slight
proliferation of the bile ducts and early portal cirrhosis were also
observed. According to the pathologist who made the examinations, the
changes observed in the liver and kidneys were of a mild, reversible
nature and probably of minor significance.
Based on published LDSo values for experimental animals (Table A.6.4)
and the apparent capacity of tetrachlorophenols to be absorbed directly
through the skin, this compound poses the greatest hazard. Trichloro-
phenols appear to present relatively minor toxicological problems. Accord-
ing to Doedens (1963), trichlorophenols are mildly toxic. Moderate skin
irritation is possible on contact, and marked irritation and possibly some
corneal injury accompanies eye contact. The dusts are likely to be very
irritating to the nose and throat. Tetrachlorophenols may be moderately
to highly toxic when ingested and highly toxic when absorbed by the skin.
Marked irritation or even a burn accompany eye contact, and dusts of these
materials are also very irritating to the respiratory tract and eyes.
Inhalation of dust is not recommended. One study reported a case of human
systemic intoxication which involved tetrachlorophenols. Truhaut, Epe"e,
and Boussemart (1952) described two fatal intoxications among wood treaters
using a solution of pentachlorophenol and sodium tetrachlorophenate. The
deaths were thought to have resulted from pentachlorophenol intoxication,
although a contribution by tetrachlorophenol in the formulation cannot be
excluded.
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203
Continuous daily contact with trichlorophenols and tetrachlorophenols
has reportedly caused acneform dermatitis in humans. The skin injury was
caused by cutaneous contact with tetrachlorophenol or its sodium salts
used for the preservation of wood. Butler (1937) described a skin condi-
tion characterized by papulofollicular lesions associated with marked
hyperkeratosis and numerous comedones and sebaceous cysts in individuals
handling a mixture of o-(2-chlorophenyl)phenol and sodium tetrachlorophe-
nate (unknown isomer). Stingily (1940) reported on patients showing
similar symptoms with certain variations; he assumed that the disturbances
were caused in part by a fungus infection. These individuals were involved
in the lumber industry, and cutaneous contact with sodium tetrachlorophe-
nate was believed responsible for onset of the lesions. The lesions lasted
over a period of years, and this chronicity was believed to be due to
underlying fungus infections.
Kleu and Goltz (1971) discussed the case histories of ten patients
suffering from chloracne due to a 15-year exposure to a trichlorophenol
formulation. A psychopathological syndrome was also reported, the inten-
sity of which increased over the 15-year period of exposure. Symptoms
included decreased sexual activity, easy fatigability, irritability, mus-
cular weakness, loss of appetite and memory, discouragement, alcohol in-
tolerance, and loss of interest. At the time the article was written, a
permanent defect was becoming evident as reduced vital psychic and intel-
lectual capacities combined with neurasthenia and mental depression. Acute
dermatitis among agricultural workers exposed to copper trichlorophenate
(Karimov, 1975) and the appearance of occupational dermatitis among workers
engaged in the production of 2,4,5-trichlorophenol (Zelikov and Danilov,
1974) have been reported in the Soviet Union. Bleiberg et al. (1964)
reported 29 cases of acquired chloracne and 11 cases of porphyria in
workers involved in the manufacture of dichlorophenol and 2,4,5-trichlo-
rophenol. The occupational environment contained acetic acid, phenol,
monochloracetic acid, and sodium hydroxide as well as 2,4-dichlorophenol
and 2,4,5-trichlorophenol. It is probable that chlorodibenzo-p-dioxins,
especially 2,3,7,8-tetrachlorodibenzo-p-dioxin, were involved in the skin
and liver lesions in the above cases.
C.6.2.2.3 Carcinogenicity - Innes et al. (1969) studied the tumori-
genicity of 130 organic compounds, including 2,4,6-trichlorophenol and
pentachlorophenol, following continuous oral administration to mice. Pen-
tachlorophenol showed no evidence of tumorigenicity. The 2,4,6-trichlo-
rophenol data were ambiguous, and the authors suggested that additional
evaluation is necessary.
Following a single initiating dose of dimethylbenzanthracene, repeated
applications of phenol and some substituted phenols are capable of causing
skin tumors in mice (Boutwell and Bosch, 1959). Mice not exposed to
dimethylbenzanthracene but treated with phenol alone for long periods also
showed tumor development. 2,4,5-Trichlorophenol was tested for tumori-
genicity and tumor-promoting activity in a similar system (Boutwell and
Bosch, 1959), and tumor-promoting activity was present; no tumor-promoting
activity was seen when 2,4,6-trichlorophenol was tested in the same system.
There is no evidence that 2,4,5-trichlorophenol causes tumors in the absence
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204
of an initiator (i.e., dimethylbenzanthracene). 2,4,5-Trichlorophenol was
approximately the same in promoting tumor formation as phenol (Table C.6.3)
Both benign and malignant tumors were formed. The hazardous effect to
humans exposed to 2,4,5-trichlorophenol is not known. Prolonged skin con-
tact is not recommended because of the potential for tumor formation and
because the compound is a primary skin irritant.
TABLE C.6.3. APPEARANCE OF SKIN TUMORS IN MICE TREATED CUTANEOUSLY WITH PHENOLS FOLLOWING
A CUTANEOUS DOSE OF 0.3% DIMETHYLBENZANTHRACENE IN ACETONE
Time animals
Treatment examined
(weeks)
Number
of mice
(survivors / total )
Survivors
with
papilloma
(%)
Survivors
with epithelial
carcinoma
(%)
Benzene control
10% phenol in benzene, no
dimethylbenzanthracene
20% phenol in acetone
20% phenol in benzene
20% 2,4,6-trichlorophenol
in benzene
21% 2,4,5-trichlorophenol
in acetone
12
20
12
24
15
16
12/12
24/30
21/24
10/33
26/29
19/20
33
58
100
0
42
13
5
20
0
,A11 received dimethylbenzanthracene except where stated.
5% at 30 weeks.
Source: Adapted from Boutwell and Bosch, 1959, Table 2, pp. 418-420. Reprinted by per-
mission of the publisher.
C.6.2.2.4 Teratogenicity - Neubert and Dillmann (1972) examined
2,4,5-trichlorophenol for embryo toxicity and teratogenic effects in
mice. 2,4,5-Trichlorophenol was administered daily by stomach tubes at
dose rates of 0.9 mg/kg body weight or 9 mg/kg body weight on days 6
through 15 of pregnancy. No teratogenic effects (as determined by an
increased number of cleft palates in offspring) were seen at either
dosage level. Slightly higher embryo mortality occurred with the 9 mg/kg
dosage; however, a statistical evaluation showed that the increase was
only marginally significant.
C.6.2.2.5 Ap las tic Anemia — One case of aplastic anemia due to pen-
tachlorophenol and tetrachlorophenol has been reported (Roberts, 1963).
The individual involved was a 21-year-old truck driver who handled lumber
soaked in a product containing pentachlorophenol (3%) and tetrachlorophe-
nol (1.5%). His clothing and hands frequently became drenched during
handling of the lumber, and some oral contamination was also indicated
because he was a habitual nail biter. Postmortem examination failed to
reveal any other cause for the aplastic anemia, and therefore, it was
concluded that the damage to the bone marrow was caused by the two chem-
icals. The precise contribution of the chlorophenols is unknown.
-------
205
SECTION C.6
REFERENCES
1. Arrhenius, E. , L. Renberg, L. Johansson, and M. Zetterqvist. 1977.
Disturbance of Microsomal Detoxication Mechanisms in Liver by Chlo-
rophenol Pesticides. Chem. Biol. Interact. 18:35-46.
2. Bjerke, E. L. , J. L. Herman, P. W. Miller, and J. H. Wetters. 1972.
Residue Study of Phenoxy Herbicides in Milk and Cream. J. Agric.
Food Chem. 20(5):963-967.
3. Bleiberg, J. , M. Wallen, R. Brodkin, and I. L. Applebaum. 1964.
Industrially Acquired Porphyria. Arch. Dermatol. 89:793-797.
4. Bb'hme, C. , and W. Grunow. 1974. Uber den Stoffwechsel von 4-(2,4,5-
Trichlorophenoxy)-buttersaure bei Ratten [Metabolism of 4-(2,4,5-
Trichlorophenoxy)-butyric Acid in Rats]. Arch. Toxicol. 32:227-231.
5. Boutwell, R. K. , and D. K. Bosch. 1959. The Tumor-Promoting Action
of Phenol and Related Compounds for Mouse Skin. Cancer Res. 19:413-
424.
6. Butler, M. G. 1937. Acneform Dermatosis Produced by Ortho (2-Chlo-
rophenyl) Phenol Sodium and Tetra-chlorphenol Sodium. Arch. Dermatol.
Syphilol. 35:251-254.
7. Chadwick, R. W. , and J. J. Freal. 1972. The Identification of Five
Unreported Lindane Metabolites Recovered from Rat Urine. Bull.
Environ. Contain. Toxicol. 7(2/3) :137-146.
8. Christensen, H. E., and T. T. Luginbyhl, eds. 1975. Registry of
Toxic Effects of Chemical Substances. U.S. Department of Health,
Education, and Welfare, Rockville, Md. pp. 861-862.
9. Clark, D. E., J. S. Palmer, R. D. Radeleff, H. R. Crookshank, and
F. M. Farr. 1975. Residues of Chlorophenoxy Acid Herbicides and
Their Phenolic Metabolites in Tissues of Sheep and Cattle. J. Agric.
Food Chem. 23(3):573-578.
10. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons, Inter-
science Publishers, New York. pp. 325-338.
11. Dow Chemical Company. 1969. Hazards Due to Toxicity and Precautions
for Safe Handling and Use. Antimicrobial Agents, Section 1-2, Dowi-
cide 2 Antimicrobial. Midland, Mich. 3 pp.
-------
206
12. Engst, R. , R. M. Macholz, M. Kujawa, H. J. Lewerenz, and R. Plass.
1976. The Metabolism of Lindane and Its Metabolites Gamma-2,3,4,5,6-
Pentachlorocyclohexene, Pentachlorobenzene, and Pentachlorophenol in
Rats and the Pathways of Lindane Metabolism. J. Environ. Sci. Health
Bll(2):95-117.
13. Farquharson, M. E., J. C. Gage, and J. Northover. 1958. The Bio-
logical Action of Chlorophenols. Br. J. Pharmacol. 13:20-24.
14. Freal, J. J., and R. W. Chadwick. 1973. Metabolism of Hexachloro-
cyclohexane to Chlorophenols and Effect of Isomer Pretreatment on
Lindane Metabolism in Rat. J. Agric. Food Chem. 21(3)»424-427.
15. Gosselin, R. E. , H. C. Hodge, R. P. Smith, and M. N. Gleason. 1976.
Clinical Toxicology of Commercial Products: Acute Poisoning, 4th
ed. Williams and Wilkins Co., Baltimore, pp. 130-132.
16. Innes, J.R.M., B. M. Ulland, M. G. Valeric, L. Petrucelli, L. Fishbein,
E. R. Hart, A. J. Pallotta, R. R. Bates, H. L. Falk, J. J. Gart, M.
Klein, I. Mitchell, and J. Peters. 1969. Bioassay of Pesticides and
Industrial Chemicals for Tumorigenicity in Mice: A Preliminary Note.
J. Natl. Cancer Inst. 42(6):1101-1114.
17. Karimov, A. M. 1975. Treatment of Pesticide Induced Dermatoses.
Vestn. Dermatol. Venerol. 5:64-65.
18. Kleu, G., and R. G£51tz. 1971. Spat- und Dauerschaden nach chronische-
gewerblicher Einwirkung von Chlorphenolbindungen (Late and Long-term
Injuries Following the Chronic Occupational Action of Chlorophenol
Compounds). Med. Klin. (Munich) 66(2):53-58.
19. Kohli, J., D. Jones, and S. Safe. 1976. The Metabolism of Higher
Chlorinated Benzene Isomers. Can. J. Biochem. 54(3):203-208.
20. Koransky, W. , G. Munch, G. Noack, J. Portig, S. Sodomann, and M.
Wirsching. 1975. Biodegradation of a-Hexachlorocyclohexane: V.
Characterization of the Major Urinary Metabolites. Naunyn-Schmiede-
berg's Arch. Pharmacol. 288:65-78.
21. Kurihara, N. , and M. Nakajima. 1974. Studies of BHC Isomers and
Related Compounds: VIII. Urinary Metabolites Produced from y-
and B-BHC in the Mouse: Chlorophenol Conjugates. Pestic. Biochem.
Physiol. 4(2):220-231.
22. McCollister, D. D., D. T. Lockwood, and V. K. Rowe. 1961. Toxico-
logic Information on 2,4,5-Trichlorophenol. Toxicol. Appl. Pharmacol.
3:63-70.
23. Mitsuda, H. , K. Murakami, and F. Kawai. 1963. Effect of Chlorophe-
nol Analogues on the Oxidative Phosphorylation in Rat Liver Mito-
chondria. Agric. Biol. Chem. 27(5):366-372.
-------
207
24. Neubert,. D. , and I. Dillmann. 1972. Embryotoxic Effects in Mice
Treated with 2,4,5-Trichlorophenoxyacetic Acid and 2,3,7,8-Tetra-
chlordibenzo-p-dioxin. Naunyn-Schmiedeberg's Arch. Pharmacol
272:243-264.
25. Roberts, H. J. 1963. Aplastic Anemia due to Pentachlorophenol and
Tetrachlorophenol. South. Med. J. 56:632-634.
26. Shafik, T. M. , H. C. Sullivan, and H. R. Enos. 1973. Multiresidue
Procedure for Halo- and Nitrophenols: Measurement of Exposure to
Biodegradable Pesticides Yielding These Compounds as Metabolites.
J. Agric. Food Chem. 21(2):295-298.
27. Stingily, K. 0. 1940. A New Industrial Chemical Dermatitis. South.
Med. J. 33(12):1268-1272.
28. Stockdale, M. , and M. J. Selwyn. 1971. Influence of Ring Substitu-
ents on the Action of Phenols on Some Dehydrogenases, Phosphokinases
and the Soluble ATPase from Mitochondria. Eur. J. Biochem. 21:416-
423.
>•
29. Truhaut, R. , P. 1'Epee, and E. Boussemart. 1952. Recherches sur
la toxicologie du pentachlorophenol: II. Intoxications profession-
nelles dans 1'Industrie du bois; observations de deux cas mortels
(Research on the Toxicology of Pentachlorophenol: II. Occupational
Poisoning in the Wood Industry; Observations on Two Fatal Cases).
Arch. Mai. Prof. Med. Trav. Secur. Soc. 13(6):567-569.
30. Wright, F. C. , J. C. Riner, J. S. Palmer, and J. C. Schlinke. 1970.
Metabolic and Residue Studies with 2-(2,4,5-Trichlorophenoxy)ethyl
2,2-Dichloropropionate (Erbon) Herbicide in Sheep. J. Agric. Food
Chem. 18(5):845-847.
31. Zelikov, A.A.K. , and L. N. Danilov. 1974. Occupational Dermatoses
(Acne) in Workers Engaged in Production of 2,4,5-Trichlorophenol.
Sov. Med. 7:145-146.
-------
C.7 ENVIRONMENTAL DISTRIBUTION AND TRANSFORMATION
C.7.1 TRENDS IN PRODUCTION AND USE
The isomers of trichlorophenol and tetrachlorophenol that are used
commercially are 2,4,5- and 2,4,6-trichlorophenol and 2,3,4,6-tetra-
chlorophenol. Dow Chemical Company is the principal producer of all
three chemicals, and they are marketed as Dowicide 2, Dowicide 2S, and
Dowicide 6 respectively. United States production of 2,4,5-trichloro-
phenol in 1968 was about 13 million metric tons (Table C.7.1). Data
from 1969 to 1975 reported to the U.S. International Trade Commission
(U.S. International Trade Commission, 1976) were withheld. Production
figures for 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol are also
unavailable. Because of the lack of information in recent years, trends
in production are difficult to evaluate.
TABLE C.7.1. PRODUCTION OF
2,4,5-TRICHLOROPHENOL, 2,4,5-T, AND
SILVEX IN THE UNITED STATES, 1965-1975
Production (metric tons)
Year „ , r
2,4,5-T* Silvex
chlorophenol
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1,817^
2,705
11,465
12,742
d
d
d
d
d
d
d
6,136
8,199
12,344
19,314
5,278
5,600
d
d
d
d
d
c
0
c
c
725
915
d
d
d
d
d
Includes 2,4,5-T acids, esters, and
salts.
^Requirement as a 2,4,5-T intermedi-
ate is subtracted from U.S. Tariff Commis-
sion figures.
^eparate figure not available.
Tfithheld to avoid disclosure.
Source: Compiled from U.S. Department
of Agriculture, 1968, 1976.
208
-------
209
The major use of 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol
is direct utilization as fungicides, particularly for the preservation of
wood, leather, and glue. 2,4,5-Trichlorophenol is used mainly as a fungi-
cide and as an intermediate in the manufacture of the herbicides 2,4,5-
trichlorophenoxyacetic acid (2,4,5-T) and silvex. These herbicides have
wide application and are especially useful for the control of woodv plants
in nonagricultural areas, forests, and range lands. Silvex is also fairly
effective against some aquatic weeds. Apparently, the main route by which
trichlorophenols and tetrachlorophenols gain entry into the environment is
by direct application and as metabolites resulting from herbicide use.
A more detailed discussion of general uses is given in Section C.2.
C.I.2 SOURCES OF POLLUTION
C.7.2.1 Distribution in Air
Investigations on the sources and distribution of trichlorophenols
and tetrachlorophenols in the atmosphere are not available. Because of
the lack of atmospheric monitoring data for these compounds, their
sources, both point and nonpoint, are only speculative. A potential for
large discharges of chlorophenols into the atmosphere exists in plants
where these compounds and the phenoxyalkanoic herbicides are manufactured.
Volatilization of the chemicals from water, soil, foliage, and impervious
surfaces may play an important role in their dispersal to the atmosphere.
Incineration of containers and trash containing chlorophenols also could
emit volatile products to the atmosphere.
C.7.2.2 Distribution in Aquatic Environments
Industrial waste discharge is the principal point source of water
pollution. During the manufacture of chlorophenols, 2,4,5-T, and silvex,
a considerable amount of chemical waste is generated by the incomplete
reaction of the starting reactants, by-product formation, and incomplete
recovery of desired products. These wastes contain a variety of chloro-
phenols and other compounds (Table B.7.2). Waste from the manufacture of
the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-T con-
tained amounts of 2,4,5-trichlorophenol ranging from a trace to 4.7%
and of 2,4,6-trichlorophenol ranging from 2.8% to 19.5% (Table B.7.3).
Other possible point sources are chemical spills and washing of con-
tainers and drums in which chlorophenols and 2,4,5-T are stored. Con-
tamination of water may arise from (1) chlorination of phenol present
either in natural water or in primary or secondary effluents of waste
treatment plants (Burttschell et al., 1959; Eisenhauer, 1964; Manufactur-
ing Chemists Association, 1972), (2) direct addition of the chemicals to
waterways, (3) degradation products of silvex used for aquatic weed con-
trol, and (4) wet and dry atmospheric fallout.
Runoff from urban and agricultural watersheds could be an important
nonpoint source of chlorophenols in aquatic environments. These chloro-
phenols are products from the degradation of 2,4,5-T and silvex, which
are widely applied to control woody plants in forests and range lands
and in nonagricultural areas such as irrigation and drainage ditches,
-------
210
roadsides, utility and railroad right-of-ways, and airfields. The con-
tribution of runoff to the chlorophenol levels in water has not yet been
documented. No other information on the distribution and sources of
trichlorophenols and tetrachlorophenols in water, aquatic organisms, and
sediments is available.
C.7.2.3 Distribution in Soil
Direct contamination of soils by trichlorophenols and tetrachloro-
phenols may be minimal. The primary source of contamination by 2,4,5-
trichlorophenol could be indirect — the application of 2,4,5-T and silvex.
As mentioned earlier, these herbicides are used mostly as brush killers
in nonagricultural areas. The herbicides 2,4,5-T and 2,4-D were applied
heavily in South Vietnam during the U.S. forest cover denial program.
Estimates show that between 1961 and 1971, about 22 million kilograms of
2,4,5-T and 26 million kilograms of 2,4-D were applied on 2 million
hectares of forest land in South Vietnam (Westing, 1972). Substantial
sprayings in neighboring Cambodia and Laos have also been reported.
Trichlorophenols and tetrachlorophenols also may be introduced indirectly
to soils by the application and degradation of pentachlorophenol (Ide et
al., 1972; Kuwatsuka and Igarashi, 1975) and lindane (Mel'nikov, 1974).
2,4,5-Trichlorophenol generated from herbicide applications could accu-
mulate and move depending on its persistence and interaction with the soil.
C.7.3 ENVIRONMENTAL FATE
C.7.3.1 Mobility and Persistence in Air
The forms in which trichlorophenols and tetrachlorophenols are trans-
ported in the atmosphere are unknown. Although these chemicals can be
dispersed into the atmosphere through volatilization, no investigations
have been made on their presence, movement, fate, and persistence.
Possibly, photodecomposition is an important mechanism of dissipation.
C.7.3.2 Mobility and Persistence in Aquatic Environments
In the aquatic environment, trichlorophenols and tetrachlorophenols
may be present as the dissolved form, associated with suspended matter
or bottom sediments, or absorbed by organisms. Hydrological factors
such as the pattern of currents and mixing and decay and migration of
organisms affect the movement of these chemicals. However, no data have
been reported to support this premise.
Ingols, Gaffney, and Stevenson (1966) utilized acclimated activated
sludge to study the degradation of 2,4,6-trichlorophenol. A 2,4,6-tri-
chlorophenol concentration of as much as 100 mg/liter did not inhibit
degradation (Table B.7.7). Complete ring cleavage of 2,4,6-trichloro-
phenol occurred in three days (Table A.7.1). The persistence of 2,4,5-
and 2,4,6-trichlorophenol in aeration lagoon effluent was reported by
Sidwell (1971). The initial concentrations of the compounds 2,4,5-tri-
chlorophenol and 2,4,5-T were 18.8 and 50.0 mg/liter, respectively, and
that of 2,4,6-trichlorophenol and 2,4,6-T were 18.5 and 53.0 mg/liter
-------
211
respectively. The pH of the acid-phenol mixture was adjusted to 7.0 just
prior to mixing with the effluent. The system was maintained at 20°C to
21°C and aerated continuously throughout the experiment. The trichloro-
phenols disappeared rapidly; degradation was apparently complete within
seven days for 2,4,5-trichlorophenol (Figure C.7.1) and within four days
for 2,4,6-trichlorophenol (Figure C.7.2).
From the limited data reported above, it appears that 2,4,5- and
2,4,6-trichlorophenol are degraded rapidly in activated sludge and aera-
tion lagoon effluent, which indicates that these media contain sufficient
nutrients and large microbial populations capable of metabolizing tri-
chlorophenols. Persistence in natural aquatic systems may vary, depend-
ing on limnological factors such as oxygen depletion, but the effect of
such factors is not known.
C.7.3.3 Mobility and Persistence in Soil
The movement of trichlorophenols and tetrachlorophenols in soil
largely depends on the interactions and persistence of the chemicals.
More persistent compounds have a greater chance to interact with the
soil, particularly by the sorption process. The extent of sorption
determines whether the chemicals are carried in association with eroded
soils during overland flow or are leached through the soil profile dur-
ing infiltration. Soil factors affecting sorption are pH, moisture, and
clay and organic matter contents.
Sorption characteristics of trichlorophenols and tetrachlorophenols
have not been studied. Presumably, trichlorophenols, due to their
weakly acidic properties, are sorbed by soil colloids in a manner similar
to the acidic pesticides such as 2,4,5-T. Weber (1972) reviewed several
investigations and concluded that acidic pesticides are sorbed only weakly
by clay and organic colloids; they are considered mobile in soil and
aquatic systems.
Microorganisms may play an important role in the dissipation of
trichlorophenols and tetrachlorophenols in soils. The persistence of
2,4,5- and 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol was
studied by Alexander and Aleem (1961) using suspensions of two silt loam
soils. Participation of soil microorganisms in the dissipation of the
chemicals was evidenced by a more rapid disappearance of incremental
additions of the compound than of initial enrichments and by inhibition
of degradation when sodium azide, a toxic agent, was added. Data showed
that 2,4,6-trichlorophenol was removed rapidly from suspensions of Dunkirk
and Mardin silt loams; removal time ranged from 5 to 13 days (Table A.7.2).
2,4,5-Trichlorophenol and 2,3,4,5-tetrachlorophenol persisted for more
than 72 days in Dunkirk silt loams. The resistance of chlorophenols to
microbial metabolism appears to be related to the positions of the chlo-
rine atom on the aromatic nucleus. Compounds containing chlorine in the
meta position, such as 2,4,5-trichlorophenol and 2,3,4,5-tetrachlorophenol,
show greater persistence. Among the tetrachlorophenols, 2,3,4,6-tetra
chlorophenol may degrade fastest (Ide et al., 1972). A similar relation-
ship was also observed for the phenoxyacetic acid herbicides.
-------
ORNL-DWG 78-10505
ORNL-DWG 78-10504
A DISTILLED WATER CONTROL
02,4,5-T
• 2,4,5-TRICHLOROPHENOL
468
TIME (days)
12
Figure C.7.1. Removal of 2,4,5-
trlchlorophenol and 2,4,5-T from solu-
tion in aeration basin effluent with
continuous aeration. Source: Adapted
from Sidwell, 1971, Figure 8, p. 70.
I I I
D DISTILLED WATER CONTROL
O 2,4,6-T
• 2,4,6-TRICHLOROPHENOL
tsS
M
to
6 8
TIME (days)
12
14
Figure C.7.2. Removal of 2,4,6-trichlorophenol
and 2,4,6-T from solution in aeration basin effluent
with continuous aeration. Source: Adapted from
Sidwell, 1971, Figure 9, p. 71.
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213
Ide et al. (1972) studied the persistence of the three isomers of
tetrachlorophenol arising from the metabolism of pentachlorophenol in
paddy soils. The isomers were incubated with soil of low organic matter
content and were maintained under reducing conditions. Figure C.7.3
shows the disappearance of the isomers in four weeks; degradation was in
the order 2,3,4,6-tetrachlorophenol > 2,3,5,6-tetrachlorophenol > 2,3,4,5-
tetrachlorophenol. Unfortunately, degradation products were not identi-
fied. Changes in the amounts of predominant degradation products of
pentachlorophenol metabolism in upland and flooded soils were investigated
by Kuwatsuka and Igarashi (1975). Significant amounts of 2,3,4,5-tetra-
chlorophenol and 2,4,6-trichlorophenol were detected; amounts were higher
under flooded conditions than in upland soils. Variable levels of 2,3,4,5-
tetrachlorophenol were observed with time, but the levels of 2,4,6-tri-
chlorophenol decreased appreciably after 20 days of incubation (Figure
C.7.4). Sharpee (1973) reported the accumulation of 2,4,5-trichlorophenol
during the degradation of 2,4,5-T in soils, but it did not persist as long
as the herbicide.
C.7.3.4 Microbial Decomposition in Soils and Aquatic Environments
Because microorganisms seem to play a major role in the dissipation
of trichlorophenols and tetrachlorophenols in the environment, these
chemicals could persist longer under conditions unfavorable for microbial
growth and activity. The microorganisms involved and possible mechanisms
of degradation are discussed below.
The microbial degradation of trichlorophenols and tetrachlorophenols
has been studied in soils (Alexander and Aleem, 1961; Ide et al. , 1972),
activated sludge (Ingols, Gaffney, and Stevenson, 1966; Nachtigall and
Butler, 1974), lagoon effluent (Sidwell, 1971), and enrichment cultures
(Chambers, Tabak, and Kabler, 1963; Chu, 1972). Nachtigall and Butler
(1974) identified Pseudomonas sp. as the bacteria in activated sludge
responsible for the metabolism of chlorophenols. Warburg respirometric
studies showed that this species oxidized 2,4,6-trichlorophenol as well
as monochlorophenols and dichlorophenols. Chambers, Tabak, and Kabler
(1963) and Tabak, Chambers, and Kabler (1964) adapted activated sludge
to phenol and found that the predominant organisms were Pseudomonas sp.,
Ackromobacter sp., and Flavobaoterium sp. This mixed culture was capable
of metabolizing monochlorophenols, dichlorophenols, and 2,4,6-trichloro-
phenol. A gram-variable bacillus designated as KC-3 was isolated from a
mixed bacterial culture which decreased the level of pentachlorophenol
in the growth medium (Chu, 1972). This isolate utilized pentachloro-
phenol as a sole source of carbon for growth with concurrent mineraliza-
tion of the compound to C02 and chloride. When 19 chlorophenols and
phenol were individually tested as growth substrates, only 2,4,6-tri-
chlorophenol and 2,3,4,6-tetrachlorophenol were able to support the growth
of KC-3 (Table C.7.2), as indicated by substrate disappearance. Soil
microorganisms capable of metabolizing trichlorophenols and tetrachloro-
phenols have not been reported. Possibly, the microorganisms adapted to
2,4,5-T (Ackramobacter sp., Myooplana sp., and Streptomyces sp.) are also
active in 2,4,5-trichlorophenol metabolism (Loos, 1975). Sharpee (19/j;
reported the metabolism of 2,4,5-T to 2,4,5-trichlorophenol in soil and
-------
214
O 2,3,4,5-TETRACHLOF)OPHENOL
D 2,3,5,6-TETRACHLOROPHENOL
• 2,3,4,6-TETRACHLOROPHENOL
TIME (weeks)
ORNL-OWG 76-10506
Figure C.7.3. Degradation of tetrachlorophenol isomers in paddy
soil. Source: Adapted from Ide et al., 1972, Figure 7, p. 1943.
Reprinted by permission of the publisher.
ORNL-OWG 78-1O507
• 2,3,4,5-TETRACHLOROPHENOL
O 2,3.6-TRICHLOROPHENOL
A 2,4,5-TRICHLOROPHENOL AND/OR
2,3,4-TRICHLOROPHENOL
• PENTACHLOROPHENOL METHYL ETHER
O 2,4,6-TRICHLOROPHENOL
20 30
TIME (days)
Figure C.7.4. Changes in amounts of pentachlorophenol degradation
products during incubation under flooded and upland conditions. Source:
Adapted from Kuwatsuka and Igarashi, 1975, Figure 4, p. 412.
-------
215
TABLE C.7.2. GROWTH OF THE BACILLUS KC-3 IN CHLOROPHENOL-MINERAL SALTS MEDIA
Substrate disappearance Viable cell count
Compound (%)
-------
216
TABLE C.7.3. METHYLATION OF 2,4,6-TRICHLOROPHENOL AND
2,3,4,6-TETRACHLOROPHENOL BY DIFFERENT FUNGAL SPECIES
Anisole formed (%)
2 4 6-Tri- 2,3,4,6-Tetra-
Fungal species chioiophenol, chlorophenol
Aspergillus sydoui
Scopulariopsis brevicaulis
Pen-ic-i Ilium crustosum
Mixed culture of the above
three fungi
Sterilized control
Uninoculated control
defined
, . a
medium
77
32
18
26
0
0
Defined
medium
74
60
50
42
0
0
Simulated
litter^
100
19
23
51
0
c
Organisms grown from six to seven days before addition of
12.4 yg 2,4,6-trichlorophenol and 17.0 yg 2,3,4,6-tetrachlorophenol
in a 20-ml medium containing glucose and further incubated for five
days.
^Organisms added to 22.5 g of sawdust containing 1220 yg
2,3,4,6-tetrachlorophenol and incubated for 29 days.
cNo data.
Source: Compiled from Curtis et al., 1974, Table 8, p. 821;
Land et al., 1975, Table 5, p. 1589. Reprinted by permission of
the publishers.
involved. The cometabolism of 2,4,5-T by benzoate-grown Bvevibaetevum
sp. produced 3,5-dichlorocatechol (Horvath, 1971), presumably through
2,4,5-trichlorophenol as an intermediate. The chlorocatechol was shown
to be metabolized completely by the Arfhrdbaoter sp. responsible for
2,4-D degradation (Bollag et al., 1968).
C.7.3.5 Pho todecomposition
Many organic compounds, including chlorophenols, undergo photo-
chemical decomposition when exposed to light. The prime requisite for
such reactions is absorption of ultraviolet light. Photochemically
induced degradation occurs at surfaces of soils, airborne particulates,
and water. Because trichlorophenol and tetrachlorophenol reach such
surfaces by various mechanisms, they are subject to exposure to sunlight
-------
217
and are therefore liable to photochemical degradation. Photodecomposi-
tion could be an important means of dissipation for trichlorophenols and
tetrachlorophenols exposed to sunlight; however, the extent of photo-
induced losses of these compounds in natural systems has not been
determined.
Specific information on the photochemical reactions of trichloro-
phenols and tetrachlorophenols is not available. An indication of their
photodecomposition can be gleaned from data obtained with closely related
compounds such as pentachlorophenol and 2,4,5-T. Crosby and Hamadmad
(1971) investigated the effect of ultraviolet light on pentachlorophenol
in methanol and aqueous suspension. 2,3,5,6-Tetrachlorophenol was the
only product detected in methanol solution. When an aqueous suspension
of pentachlorophenol was irradiated, only small amounts of 2,3,5,6-tetra-
chlorophenol were detected; the major product was humic acid.
Photodecomposition of the herbicide 2,4,5-T in aqueous solution by
ultraviolet light yielded products analogous to those produced by irradia-
tion of 2,4-D (Figure C.7.5). The major products were 2,4,5-trichloro-
phenol and 2-hydroxy-4,5-dichlorophenoxyacetic acid; colored polymeric
products were eventually formed. Photolysis involved cleavage of the
ether bond and replacement of the ring chlorine by hydrogen and hydroxyl
groups. The rate of photolysis, although more rapid at pH 8 than at pH
3, was slow compared with the rates for 4-chlorophenoxyacetic acid and
2,4-D. However, under the same conditions, the photolysis rate of 2,4,5-
trichlorophenol was rapid, indicating that side chain oxidation was the
rate-limiting step in 2,4,5-T photodecomposition.
ORNL- DWG 78 -18090
POLYMER
T\
2-HYDROXY-4.5-OICHLORO-
PHENOXYACETIC ACID '
Cl
4,5-DICHLORO-
CATECHOU
k VOLATILE PRODUCT
Figure C.7.5. Proposed photodecomposition pathway for 2,4,5-T in
aqueous solution. Source: Adapted from Crosby and Wong, 1973, Figure
p. 1053. Reprinted by permission of the publisher.
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218
The possibility of chlorodioxin formation during photolysis of
environmental 2,4,5-trichlorophenol is of concern, although no data have
been reported. Crosby and Wong (1973) detected no chlorodioxin produc-
tion during the photolysis of 2,4,5-T.
C.7.3.6 Pyrolysis
It has been reported that commercially produced higher chlorophenols
and 2,4,5-T are contaminated with chlorodioxins, compounds which have
teratogenic effects and high toxicity (Firestone et al., 1972; Woolson,
Thomas, and Ensor, 1972). Dioxins are formed when reaction temperatures
for producing chlorophenols exceed 160°C under pressure. Concern over
environmental contamination by chlorodioxins stems from the widespread
application of 2,4,5-T (Helling et al., 1973). Chlorodioxins could also
be introduced into the environment by incineration of solid waste contain-
ing chlorophenols and chlorophenol-treated materials or by heating fat
which is contaminated with chlorophenols. Pyrolytic condensation of
chlorophenols to chlorodioxins has been demonstrated (Higginbotham et
al., 1968; Langer, Brady, and Briggs, 1973). Langer, Brady, and Briggs
(1973) reported chlorodioxin yields of 80%, 30%, 15%, <1%, and <3% for
the sodium salts of pentachlorophenol, 2,3,4,6-tetrachlorophenol, 2,4,6-
trichlorophenol, 2,4,5-trichlorophenol, and 2,4-dichlorophenol respec-
tively. Data suggest that a high degree of chlorination and chlorine
in the ortho position on the aromatic ring, combined with thermal treat-
ment, favor dioxin formation. The pyrolytic method of converting chloro-
phenols to dioxins was used by Flick, Firestone, and Higginbotham (1972)
and Higginbotham et al. (1968) to obtain samples for toxicological
evaluation.
Results of laboratory studies involving the heating of concentrated
phenols at controlled temperatures do not necessarily duplicate condi-
tions encountered in the burning of waste materials. Temperatures en-
countered in incineration are higher, and chlorophenols may vaporize
before chlorodioxins can be formed. For example, Stehl et al. (1973)
showed that octachlorodibenzo-p-dioxin levels did not increase when wood
or paper treated with pentachlorophenol was combusted. More recently,
Ahling and Johansson (1977) found that when pentachlorophenol was com-
busted at 600°C or 800°C, octachlorodioxin formation did not occur.
C.7.4 WASTE MANAGEMENT
Chlorophenols from various sources and/or reactions are found in
natural waters and wastewater. Concentrations range from low in natural
waters to high in wastewater effluents coming from the manufacture of
chlorophenols and phenoxyalkanoic herbicides. Treatment processes appli-
cable to wastewaters containing trichlorophenol and tetrachlorophenol
and the removal of these chemicals from drinking waters are discussed in
this section.
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219
C.7.4.1 Primary Treatment
Primary treatment consists essentially of settling solids after
screening off the larger materials. No reports on the effectiveness of
settling as a means of removal of trichlorophenols and tetrachlorophenols
from wastewater are available.
C.7.4.2 Secondary Treatment
Secondary treatment uses biological processes for the removal of
organic matter from wastewater. Biological methods used in waste treat-
ment include trickling filters, activated sludge, and oxidation ponds.
These methods are based on the principle that microorganisms utilize
organic materials in wastewaters as a source of energy and in so doing
convert them to simpler, less toxic substances. Limited evidence indi-
cates that trichlorophenols and tetrachlorophenols are biodegradable;
consequently, secondary treatment should provide an excellent method for
the removal of these chemicals. Sidwell (1971) investigated biological
treatment of wastes generated from the manufacture of 2,4-D and 2,4,5-T
by using a combined aerated lagoon and stabilization pond. These experi-
ments are described in Section B.7.4.2. In vitro experiments with indi-
vidual chlorophenols, including 2,4,5- and 2,4,6-trichlorophenol, and
corresponding chlorophenoxy acids diluted with aeration lagoon effluent
indicated that these compounds are decomposed in less than seven days
(Figures C.7.1 and C.7.2).
C.7.4.3 Soil Disposal
Soil disposal can be a means of biological treatment of chloro-
phenolic wastes. However, the possibility of treating wastes which
contain trichlorophenols and tetrachlorophenols by this method has not
been explored.
C.7.4.4 Chemical Oxidation
Chlorine, besides being used to disinfect drinking water and efflu-
ents from primary and secondary treatment plants, is also utilized for
the oxidation of chlorophenols and other organic compounds. According
to Burttschell et al. (1959) and confirmed by others (Eisenhauer, 1964;
Manufacturing Chemists Association, 1972), the chlorination of phenol
proceeds with stepwise substitution in the 2, 4, and 6 positions of the
aromatic ring (Figure C.7.6). The ultimate chlorophenol product is
2,4,6-trichlorophenol, which after further chlorination is oxidized to
form a mixture of nonphenolic products. The rate of reaction of aqueous
chlorine and phenol to form chlorophenols is highly pH dependent, with
the maximum rate occurring in the neutral or slightly alkaline pH range
(PH 7 to 8) (Lee and Morris, 1962).
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220
ORNL-DWG 78-105O8
(2 mg/liter)
2-CHLOROPHENOL
(3 mg/liter)
2,6 - DIC H LOROPHENOL
(>10OOmg/|i*erl
PHENOL
OH
-OXIDATION
Cl
(>1000 mg/liter)
2,4.6-TRICH LOROPHENOL
a
(250 mg/liter)
4-CHLORO PHENOL
a
(2 mg/liter)
2,4-DICHLOROPHENOL
Figure C.7.6. Reaction scheme for the chlorination of phenol.
Numbers in parentheses indicate odor threshold concentrations. Source:
Adapted from Burttschell et al., 1959, Figure 3, p. 212. Reprinted with
permission of the American Water Works Association from JOURNAL AWWA,
Volume 51, copyrighted 1959.
C.7.4.5 Ion Exchange
Although ion-exchange resins may have the capacity to absorb tri-
chlorophenols and tetrachlorophenols, this ability has not been demonstrated.
C.7.4.6 Activated Carbon Adsorption
Activated carbon is effective in adsorbing several organic compounds
from water. Investigations specifically dealing with the utilization of
activated carbon for the removal of trichlorophenols and tetrachlorophenols
have not been performed. However, the adsorption of various phenoxyacetic
acids by charcoal may provide insight into the possible adsorption be-
havior of the various trichlorophenol and tetrachlorophenol isomers.
Leopold, van Schaik, and Neal (1960) studied the removal of 18 phenoxy-
acetic acids from water by activated carbon to show the relationship
between molecular structure of chlorinated phenoxyacetic acids and
adsorption on activated carbon (Table C.7.4). One, two, and three
chlorine substitutions in the phenyl ring increased the adsorptive prop-
erties of the molecule. An inverse correlation between adsorption and
solubility was found; successive chlorinations decreased solubility and
increased adsorption. Apparently, trichlorophenols and tetrachlorophenols,
due to their extremely low water solubilities, also are adsorbed by char-
coal quite extensively.
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221
TABLE C.7.4.
ADSORPTION OF CHLORINATED PHENOXYACETIC ACIDS BY
ACTIVATED CARBON
Compound
Phenoxyacetic acid
2-Chlorophenoxyacetic acid
3-Chlorophenoxyacetic acid
4-Chlorophenoxyacetic acid
2,3-Dichlorophenoxyacetic acid
2 , 4-Dichlorophenoxyacetic acid
2,5-Dichlorophenoxyacetic acid
2 , 6-Dichlorophenoxyacetic acid
3, 4-Dichlorophenoxyacetic acid
3 , 5-Dichlorophenoxyacetic acid
2,3,4-Trichlorophenoxyacetic acid
2,3, 5-Trichlorophenoxyacetic acid
2,3,6-Trichlorophenoxyacetic acid
2, 4, 5-Trichlorophenoxyacetic acid
2,4,6-Trichlorophenoxyacetic acid
3, 4, 5-Trichlorophenoxyacetic acid
2,3,4, 6-Tetrachlorophenoxyacetic acid
2,3,4,5, 6-Pentachlorophenoxyacetic acid
Adsorption*2
(%)
8
29
35
35
58
49
48
32
46
53
64
64
43
65
51
70
59
66
Solubility
(x 10 "3 iV)
110
6.85
12.65
5.13
1.55
2.36
2.42
7.05
2.07
4.35
0.80
1.00
2.40
1.05
0.97
1.15
0.39
0.18
Equimolar concentrations, 10"
Source: Adapted from Leopold, van Schaik. and Neal, Tables 1
and 2, p. 51. Reprinted by permission of the publisher.
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222
SECTION C.7
REFERENCES
1. Ahling, B., and L. Johansson. 1977. Combustion Experiments Using
Pentachlorophenol on a Pilot Scale and Full-Scale. Chemosphere
7:425-437.
2. Alexander, M., and M.I.H. Aleem. 1961. Effect of Chemical Struc-
ture on Microbial Decomposition of Aromatic Herbicides. J. Agric.
Food Chem. 9(1):44-47.
3. Bollag, J. M. , G. G. Briggs, J. E. Dawson, and M. Alexander. 1968.
2,4-D Metabolism: Enzymatic Degradation of Chlorocatechols. J.
Agric. Food Chem. 16(5):829-833.
4. Burttschell, R. H., A. A. Rosen, F. M. Middleton, and M. B. Ettinger.
1959. Chlorine Derivatives of Phenol Causing Taste and Odor. J.
Am. Water Works Assoc. 51:205-214.
5. Chambers, C. W., H. H. Tabak, and P. W. Kabler. 1963. Degradation
of Aromatic Compounds by Phenol-Adapted Bacteria. J. Water Pollut.
Control Fed. 35(12):1517-1528.
6. Chu, J. P. 1972. Microbial Degradation of Pentachlorophenol and
Related Chlorophenols. Ph.D. Thesis. Purdue University, Lafayette,
Ind. 117 pp.
7. Crosby, D. G., and N. Hamadmad. 1971. The Photoreduction of Penta-
chlorobenzenes. J. Agric. Food Chem. 19(6):1171-1174.
8. Crosby, D. G., and A. S. Wong. 1973. Photodecomposition of 2,4,5-
Trichlorophenoxyacetic Acid (2,4,5-T) in Water. J. Agric. Food
Chem. 21(6):1052-1054.
9. Curtis, R. F., C. Dennis, J. M. Gee, M. G. Gee, N. M. Griffiths,
D. G. Land, J. L. Peel, and D. Robinson. 1974. Chloroanisoles as
a Cause of Musty Taint in Chickens and Their Microbiological Forma-
tion from Chlorophenols in Broiler House Litters. J. Sci. Food
Agric. 25:811-828.
10. Eisenhauer, H. R. 1964. Oxidation of Phenolic Wastes: Part I.
Oxidation with Hydrogen Peroxide and a Ferrous Salt Reagent. J.
Water Pollut. Control Fed. 36(9):1116-1128.
11. Firestone, D., J. Ress, N. L. Brown, R. P. Barren, and J. N. Damico.
1972. Determination of Polychlorodibenzo-p-dioxins and Related Com-
pounds in Commercial Chlorophenols. J. Assoc. Off. Anal. Chem.
55(l):85-92.
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223
12. Flick, D. F., D. Firestone, and G. R. Higginbotham. 1972. Studies
on Chick Edema Disease: 9. Response of Chicks Fed or Singly Admin-
istered Synthetic Edema-Producing Compounds. Poult. Sci. 51-2026-
2034.
13. Helling, C. S., A. R. Isensee, E. A. Woolson, P.D.J. Ensor, G. E.
Jones, J. R. Plimmer, and P. C. Kearney. 1973. Chlorodioxins in
Pesticides, Soils, and Plants. J. Environ. Qual. 2(2):171-178.
14. Higginbotham, G. R. , A. Huang, D. Firestone, J. Verrett, J. Ress, and
A. D. Campbell. 1968, Chemical and Toxicological Evaluations of
Isolated and Synthetic Chloro Derivatives of Dibenzo-p-dioxin.
Nature (London) 220:702-703.
15. Horvath, R. S. 1971. Microbial Cometabolism of 2,4,5-Trichloro-
phenoxyacetic Acid. Bull. Environ. Contain. Toxicol. 5(6) :537-541.
16. Ide, A., Y. Niki, F. Sakamoto, I. Watanabe, and H. Watanabe. 1972.
Decomposition of Pentachlorophenol in Paddy Soil. Agric. Biol. Chem.
36(11):1937-1944.
17. Ingols, R. S., P. E. Gaffney, and P. C. Stevenson. 1966. Biological
Activity of Halophenols. J. Water Pollut. Control Fed. 38(4) :629-635.
18. Kearney, P. C. , E. A. Woolson, and C. P. Ellington, Jr. 1972. Per-
sistence and Metabolism of Chlorodioxins in Soils. Environ. Sci.
Technol. 6(12):1017-1019.
19. Kuwatsuka, S. , and M. Igarashi. 1975. Degradation of PCP in Soils:
II. The Relationship between the Degradation of PCP and the Proper-
ties of Soils, and the Identification of the Degradation Products of
PCP. Soil Sci. Plant Nutr. (Tokyo) 21(4):405-414.
20. Land, D. G. , M. G. Gee, J. M. Gee, and C. A. Spinks. 1975. 2,4,6-
Trichloroanisole in Broiler House Litter: A Further Cause of Musty
Taint in Chickens. J. Sci. Food Agric. 26:1585-1591.
21. Langer, H. G. , T. P. Brady, and P. R. Briggs. 1973. Formation of
Dibenzodioxins and Other Condensation Products from Chlorinated Phe-
nols and Derivatives. Environ. Health Perspect. 5:3-7.
22. Lee, G. F., and J. C. Morris. 1962. Kinetics of Chlorination of
Phenol — Chlorophenolic Tastes and Odors. Water Res. 6:419-431.
23. Leopold, A. C., P. van Schaik, and M. Neal. 1960. Molecular Struc-
ture and Herbicide Adsorption. Weeds 8:48-54.
24. Loos, M. A. 1975. Phenoxyalkanoic Acids. In: Herbicides, P. C.
Kearney and D. D. Kaufman, eds. Marcel Dekker, New York. pp. 1-128.
25. Lyr, H. 1962. Detoxification of Heartwood Toxins and Chlorophenols
by Higher Fungi. Nature (London) 195:289-290.
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224
26. Manufacturing Chemists Association. 1972. The Effect of Chlorina-
tion on Selected Organic Chemicals. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, B.C. 103 pp,
27. Mel'nikov, N. N. 1974. Pesticides and the Environment: Gamma-
hexachlorocyclohexane. Khim Sel'sk. Khoz. 12(9):631-635.
28. Nachtigall, M. H., and R. G. Butler. 1974. Metabolism of Phenols
and Chlorophenols by Activated Sludge Microorganisms (abstract).
Abstr. Annu. Meet. Am. Soc. Microbiol. 1974:184.
29. Sharpee, K. W. 1973. Microbial Degradation of Phenoxy Herbicides
in Culture, Soil, and Aquatic Ecosystems. Diss. Abstr. Int. B
34(3):954.
30. Sidwell, A. E. 1971. Biological Treatment of Chlorophenolic Wastes:
The Demonstration of a Facility for the Biological Treatment of a
Complex Chlorophenolic Waste. Water Pollution Control Research
Series. U.S. Environmental Protection Agency, Washington, D.C.
177 pp.
31. Stehl, R. H. , R. R. Papenfuss, R. A. Bredeweg, and R. W. Roberts.
1973. The Stability of Pentachlorophenol and Chlorinated Dioxins
to Sunlight, Heat, and Combustion. Adv. Chem. Ser. 120:119-125.
32. Tabak, H. H., C. W. Chambers, and P. W. Kabler. 1964. Microbial
Metabolism of Aromatic Compounds: I. Decomposition of Phenolic
Compounds and Aromatic Hydrocarbons by Phenol-Adapted Bacteria. J.
Bacteriol. 87(4):910-919.
33. U.S. Department of Agriculture. 1968. The Pesticide Review 1968.
Washington, D.C. 54 pp.
34. U.S. Department of Agriculture. 1976. The Pesticide Review 1975.
Washington, D.C. 40 pp.
35. U.S. International Trade Commission. 1976. Synthetic Organic
Chemicals: United States Production and Sales, 1974. Washington,
D.C. pp. 21-194.
36. Weber, J. B. 1972. Interaction of Organic Pesticides with Particu-
late Matter in Aquatic and Soil Systems. Adv. Chem. Ser. 111:55-120.
37. Westing, A. H. 1972. Herbicides in War: Current Status and Future
Doubt. Biol. Conserv. 4(5):322-327.
38. Woolson, E. A., R. F. Thomas, and P.D.J. Ensor. 1972. Survey of
Polychlorodibenzo-p-dioxin Content in Selected Pesticides. J. Agric.
Food Chem. 20(2):351-354.
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C.8 ENVIRONMENTAL INTERACTIONS AND THEIR CONSEQUENCES
C.8.1 ENVIRONMENTAL CYCLING OF TRICHLOROPHENOLS AND TETRACHLOROPHENOLS
The sources, distribution, and fate of 2,4,5- and 2,4,6-trichloro-
phenol (mention of trichlorophenols in the ensuing discussion includes
both of these isomers and excludes other trichlorophenol isomers) and
tetrachlorophenols in soils, aquatic environments, and the atmosphere
are discussed in Section C.I. Figure A.8.1 depicts the possible cycling
of these chemicals in the environment and indicates the probable sources
of contamination, interactions, and sinks. This scheme should be inter-
preted with caution because information gaps make it difficult to ascer-
tain patterns of distribution, accumulation, and flow of the chemicals
into various parts of the environment.
Contamination of soil and aquatic systems could occur through direct
application of the chemicals or compounds derived from them, discharge of
industrial waste and sewage, or chlorination of water containing phenol
and/or lower chlorophenols. The relative contribution from each source
has not been determined. However, contamination probably results mainly
from direct usage of 2,4,5- and 2,4,6-trichlorophenol and 2,3,4,6-tetra-
chlorophenol as fungicides for wood preservation and from application of
pesticides such as 2,4,5-trichlorophenoxyacetic acid (2,4,5-1), silvex,
ronnel, lindane, and pentachlorophenol, which upon degradation yield one
or more of the trichlorophenols and tetrachlorophenols as metabolite(s).
Furthermore, technical pentachlorophenol contains 10% to 20% 2,3,4,6-
tetrachlorophenol as a contaminant (Parr et al., 1974). Significant
contamination may be contributed by discharge of chlorophenolic wastes
from chemical plants producing chlorophenols and related products. Al-
though trichlorophenols and tetrachlorophenols are quite susceptible to
volatilization, their presence in the atmosphere and their subsequent
redeposition during precipitation and fallout has not been documented.
Volatilization and leaching from treated material, particularly wood,
can occur to some extent.
Trichlorophenols and tetrachlorophenols may undergo physicochemical
and biological interactions with various components of the environment.
The extent of sorption by soil colloids determines whether the chemicals
are carried in association with eroded soil during overland flow or are
leached through the soil profile during infiltration. Unfortunately,
data on sorption of these chemicals by soil and by sediments and airborne
particulate materials are not available. They are probably sorbed ex-
tensively by natural sorbents due to their weakly acidic nature and low
water solubility, although binding might be relatively weak, making them
moderately mobile. The rates of chemical and biological transformations
determine their persistence and subsequent degree of movement and trans-
port in a particular segment of the environment. Chemical oxidation can
occur during treatment of wastewater (Section C.7.4.4), and photodecom-
position is a possibility when these chemicals are exposed to sunlight
(Section C.7.3.5). Microorganisms may play a major role in the dissipa-
tion of trichlorophenols and tetrachlorophenols (Section C.7.3). Possibly,
225
-------
226
microbial degradation is the main mechanism by which these chemicals are
removed from the environment. The degree of metabolism and mode of dis-
tribution of absorbed or ingested trichlorophenols and tetrachlorophenols
in plants, wildlife, domestic animals, and other mammals can influence
biological accumulation. If these chemicals are bioaccumulated and per-
sist, they can be returned to the soil and water systems during decay
and excretion or be consumed by higher biota, including humans, through
the food chain. There is a lack of information regarding the metabolic
fate and distribution of trichlorophenols and tetrachlorophenols in higher
organisms.
C.8.2 TRICHLOROPHENOLS AND TETRACHLOROPHENOLS IN FOOD
Agricultural crops and domestic animals may indirectly become con-
taminated with trichlorophenols and tetrachlorophenols by absorption and/or
ingestion of the pesticides 2,4,5-T, silvex, lindane, and pentachloro-
phenol. Kohli, Weisgerber, and Klein (1976) found that lindane absorbed
from nutrient solution by lettuce plants was metabolized to free and con-
jugated 2,3,4,6-tetrachlorophenol. However, no reports indicate the pres-
ence and metabolic fate of trichlorophenols and tetrachlorophenols in
field-grown crops. Residues of 2,4,5-trichlorophenol occurred in the
kidney and liver of sheep and cattle fed with high concentrations (300
to 2000 mg/kg) of 2,4,5-T and silvex (Clark et al., 1975). Negligible
residues were found in fat and muscle. 2,4,5-Trichlorophenol has been
found in milk and cream of cows fed diets containing 100 to 1000 mg/kg
2,4,5-T (Bjerke et al., 1972). Milk and cream of cows that received
10 to 30 mg/kg of 2,4,5-T were free from detectable amounts of 2,4,5-
trichlorophenol. Large amounts of 2,4,5-T and silvex, such as the con-
centrations used in the above studies, are not likely to be found in
feed, forage, and pasture. Proper use of these herbicides should result
in negligible residues of 2,4,5-trichlorophenol in meat and milk.
Because of the extensive use of wood shavings as a cheap source of
litter, largely for broiler chickens, but also for turkeys, ducks, pigs,
and cattle, continued use of shavings originating from preservative-
treated wood may constitute an environmental hazard. Furthermore, spent
litter is being used increasingly as a constituent of animal feeds.
Limited information indicates that contamination of foodstuff by residues
of trichlorophenols and tetrachlorophenols appears unlikely. However, the
occurrence of musty taint in chickens due to the presence of 2,4,6-tri-
chloroanisole and 2,3,4,6-tetrachloroanisole reduces appreciably the
quality of poultry meat and eggs (Curtis et al., 1974; Land et al., 1975).
These anisoles are formed through fungal methylation of 2,4,6-trichloro-
phenol and 2,3,4,6-tetrachlorophenol present in wood shavings used as
broiler litter. Substantial amounts of 2,3,4,6-tetrachlorophenol, rang-
ing from 4 to 307 mg/kg, have been detected in wood shavings and sawdust
originating from preservative-treated wood (Curtis et al., 1972; Parr
et al., 1974). These figures imply that a large volume of 2,3,4,6-
tetrachlorophenol is used as a wood preservative, but the contribution
of 2,3,4,6-tetrachlorophenol from pentachlorophenol, either as a con-
taminant or degradation product, should not be discounted. The presence
of 2,4,6-trichlorophenol in broiler litter may result either from its
-------
227
use as a wood preservative (Land et al., 1975), from degradation of
pentachlorophenol (Land et al., 1975), or from disinfectants used in
chicken houses (Orr et al., 1975).
Potential hazards exist probably not through contamination of food-
stuff but in the use of wood shavings for litter for domestic animals and
introduction of chlorodioxins into the environment via pyrolysis. More
investigations are needed in order to appraise properly the environmental
hazards associated with the use of trichlorophenols and tetrachlorophenols,
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228
SECTION C.8
REFERENCES
1. Bjerke, E. L., J. L. Herman, P. W. Miller, and J. H. Wetters. 1972.
Residue Study of Phenoxy Herbicides in Milk and Cream. J. Agric.
Food Chem. 20(5):963-967.
2. Clark, D. E., J. S. Palmer, R. D. Radeleff, H. R. Crookshank, and
F. M. Farr. 1975. Residues of Chlorophenoxy Acid Herbicides and
Their Phenolic Metabolites in Tissues of Sheep and Cattle. J. Agric.
Food Chem. 23(3):573-578.
3. Curtis, R. F., C. Dennis, J. M. Gee, M. C. Gee, N. M. Griffiths, D. G.
Land, J. L. Peel, and D. Robinson. 1974. Chloroanisoles as a Cause
of Musty Taint in Chickens and Their Microbiological Formation from
Chlorophenols in Broiler House Litters. J. Sci. Food Agric. 25(7):
811-828.
4. Curtis, R. F., D. G. Land, N. M. Griffiths, M. Gee, D. Robinson, J.
L. Peel, C. Dennis, and J. M. Gee. 1972. 2,3,4,6-Tetrachloroanisole
Association with Musty Taint in Chickens and Microbiological Forma-
tion. Nature (London) 235:223-224.
5. Kohli, J., I. Weisgerber, and W. Klein. 1976. Balance of Conversion
of [1'*C]Lindane in Lettuce in Hydroponic Culture. Pestic. Biochem.
Physiol. 6:91-97.
6. Land, D. G., M. G. Gee, J. M. Gee, and C. A. Spinks. 1975. 2,4,6-
Trichloroanisole in Broiler House Litter: A Further Cause of Musty
Taint in Chickens. J. Sci. Food Agric. 26(10):1585-1591.
7. Orr, H. L. , J. P. Walker, G. W. Friars, and N. A. Fish. 1975. Chem-
ical Sanitizer Influences on the Flavor of Chicken Broilers. Poult.
Sci. 54(4):1031-1035.
8. Parr, L. J., M. G. Gee, D. G. Land, D. Robinson, and R. F. Curtis.
1974. Chlorophenols from Wood Preservatives in Broiler House Litter.
J. Sci. Food Agric. 25:835-841.
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PART D
PENTACHLOROPHENOL
229
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D.I SUMMARY
D.I.I DISCUSSION OF FINDINGS
Pentachlorophenol is a white, needlelike, crystalline solid. Because
of its high degree of insolubility in water, the water-soluble sodium salt
is often substituted for many uses. Although pentachlorophenol is only
slightly soluble in water, it is readily soluble in organic solvents and
is sufficiently volatile to distill with steam. Its vapor pressure is
relatively low, but losses of *pentachlorophenol from soils, water, and
preservative-treated items through volatilization may occur. The compound
is relatively stable and is rather inert chemically. Although it is not
subject to easy oxidative coupling or electrophilic substitution reactions
common to most phenols, the polar hydroxyl group tends to facilitate bio-
logical degradation. Any monovalent alkali metal salt of pentachlorophenol
is soluble in water, but the protonated (phenolic) form is virtually insol-
uble. Hence, transport of pentachlorophenol in water depends largely on
the pH of the system. Pentachlorophenol and its salts are extensively used
as broad-spectrum biocides. About 90% to 95% of the amount produced in the
United States is used in the preservation of wood; the remaining 5% to 10%
has a large number of applications in industry and agriculture. The com-
pounds have been used as herbicides or preharvest desiccants, as algicides,
as molluscicides for eradication of a snail which serves as intermediate
host for the human schistosomes, and in food processing plants and pulp
mills for control of slime and mold. Pentachlorophenol and sodium penta-
chlorophenate also have been used as fungicides and/or bactericides in the
processing of cellulosic products, starches, adhesives, paints, leathers,
oils, rubber, textiles, and wooden crates used for packaging raw agricul-
tural products. Approximately 25,000,000 kg of pentachlorophenol and
sodium pentachlorophenate are produced annually, and because of the wide
distribution, a potential for environmental contamination exists.
A variety of qualitative and quantitative techniques have been devel-
oped for the analysis of pentachlorophenol. In general, colorimetric and
oxidation methods of analysis are less sensitive and specific than chromato-
graphic methods. The most widely used and effective technique for analysis
of pentachlorophenol in many sample types is gas-liquid chromatography.
The electron-capture detector is used routinely because of its high sensi-
tivity for quantities in the nanogram to picogram range. When rigorous
identification is required, final confirmation may be made by ultraviolet
or infrared spectrophotometry. Efficient extraction of pentachlorophenol
from soils, water, and biological materials depends on many factors deter-
mined by the type of sample to be analyzed. The advantages and disadvan-
tages of different methods of sample storage, preparation, and analysis
are discussed in Sections D.2.6.1 and D.2.6.2.
Pentachlorophenol is extremely toxic to almost all forms of bacteria,
algae, and fungi. For this reason, pentachlorophenol is a well-known and
widely used antimicrobial substance. Detailed information on the mechanism
of pentachlorophenol toxicity to microorganisms is scant. It is believed
that uncoupling oxidative phosphorylation is of major importance in the
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toxicity of pentachlorophenol to bacteria. However, other vital bacterial
processes must also be affected because anaerobes (bacteria not dependent
on oxidative phosphorylation for their energy source) are also sensitive
to this compound. An effect of pentachlorophenol on the generation of ATP
by substrate-level phosphorylation has been reported. Thus, the compound
not only affects oxidative phosphorylation, but also affects either the
generation of ATP at the level of glycolysis or the effective utilization
of the ATP generated. Bacteria resistant to the toxic effect of pentachlo-
rophenol and some strains capable of degrading pentachlorophenol have been
isolated. In most cases, both resistant strains and those able to degrade
pentachlorophenol were isolated from sites exposed routinely to the com-
pound (e.g., pentachlorophenol-treated wood and soil from the grounds of
wood treatment plants). The prevalence of pentachlorophenol-resistant
bacteria in the general environment is unknown. The high toxicity of pen-
tachlorophenol to most fungi determines its effectiveness as a wood pre-
servative. Some fungal species have been isolated which are capable of
tolerating pentachlorophenol and in some cases detoxifying it. The mech-
anism of pentachlorophenol detoxification by fungi is not well understood;
however, methylation of the compound to produce pentachloroanisole is a
common mechanism. Pentachlorophenol is also highly toxic to algae and has
been used as an algicide in paddy fields and industrial facilities. Algae
tolerant to the effect of pentachlorophenol have not been described, and
metabolism of pentachlorophenol by algae has not been reported.
Pentachlorophenol is absorbed rapidly by the roots of sugar cane, but
it is not readily translocated, remaining primarily at the site of treat-
ment until metabolized or released from the plant tissue. Some transloca-
tion has been demonstrated in cotton plants following foliar application.
It is not known whether pentachlorophenol readily translocates in other
plants, and the subject warrants further investigation.
Pentachlorophenol is highly toxic to plants and has been used as
both a contact and preemergence herbicide. Uncoupling of oxidative phos-
phorylation likely is responsible for the phytotoxic effects. Germina-
tion suppression may be caused by phytate decomposition in germinating
seedlings. Severe damage to tomato plants and conifer seedlings planted
in pentachlorophenol-treated wooden flats has been reported. In at least
one case, the phytotoxicity was ascribed to volatilization of pentachlo-
rophenol from the wood and subsequent atmospheric transport. Severe dam-
age was reported in high-density apple orchards where posts freshly treated
with pentachlorophenol were used as supports for the trees. Except for
herbicide use, exposure of plants to pentachlorophenol should be strictly
avoided. Pentachlorophenol is also toxic to aquatic plants; 50% lethality
of duck weed (Lerrma minor) occurs at a concentration of 0.32 mg/liter.
Furthermore, pentachlorophenol reportedly increases the number of chro-
mosomal abnormalities in root tip preparations of water hyacinth and
causes abnormal mitoses in the European broad bean.
Pentachlorophenol is toxic to wild and domestic animals following
cutaneous absorption or ingestion. No information on the possible respi-
ratory toxicity of pentachlorophenol or sodium pentachlorophenate to wild
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and domestic animals is available. Pentachlorophenol is absorbed readily
by the cutaneous route during direct, long-term exposure to freshly treated
wood. Losses of sows and their litters have been reported when pigs have
been confined to farrowing houses freshly, or inappropriately (i.e., exces-
sive quantities), treated with pentachlorophenol in the absence of bedding.
This effect can be reversed by appropriate treatment and provision of bed-
ding to prevent direct contact. Swine, sheep, and cattle have been exposed
to pentachlorophenol-treated gates, watering troughs, feeding troughs,
salt boxes, posts, electric fence stakes, and corral timbers for up to two
months. No apparent detrimental effects on the animals were noted; how-
ever, the pentachlorophenol levels in the animals were not determined, and
the experiments were insufficient to evaluate chronic long-term effects of
pentachlorophenol-treated wood on livestock. Although the lack of infor-
mation prevents definitive conclusions, preservative-treated wood likely
poses no serious hazard to domestic animals if the wood is properly treated
and used.
Pentachlorophenol is apparently repellent to animals. Cattle avoid
pasture treated with a herbicidal formulation of pentachlorophenol, and
rats decrease their food intake when their diet includes pentachlorophenol
at levels of 1000 ppm or more. Cats refuse diets containing 125 ppm. Nev-
ertheless, domestic animals have ingested sufficient amounts of pentachlo-
rophenol to cause death. Substantial quantities of pentachlorophenol (120
to 140 mg/kg body weight) administered in the form of pentachlorophenol-
impregnated sawdust were required to cause death in calves and sheep.
Based on a standard loading approximating pentachlorophenol levels in the
outer layer of treated wood, ingestion of approximately 600 g of penta-
chlorophenol-treated wood would be required to cause acute lethal intoxi-
cation. Therefore, it seems unlikely that acute toxicity will result from
ingestion of treated wood over a short period. The question of chronic
toxicity from pentachlorophenol-treated wood remains an open one. Despite
the repellent characteristics of pentachlorophenol, the hazard posed by
concentrated solutions of the compounds in the vicinity of domestic ani-
mals is quite real. Poisoning resulting from the consumption of a solution
of pentachlorophenol in kerosene by a thirsty cow has been reported. The
lesson is clear — concentrated solutions of these substances should be
removed from the vicinity of domestic animals. However, the hazard posed
by pentachlorophenol-treated wood is not clear-cut.
Whether pentachlorophenol is absorbed by the cutaneous, respiratory,
or gastrointestinal route, the compound is transported by the blood. High
concentrations have been detected in the kidneys and livers of animals
dosed with the compound. Based on investigations with experimental ani-
mals, biotransformation in domestic and wild animals probably involves
the formation of pentachlorophenol conjugates (including glucuronides),
tetrachlorohydroquinone, tetrachlorohydroquinone conjugates, and cnloranil.
Metabolism probably occurs primarily in the liver. Pentachlorophenol is
excreted in the urine and feces of animals dosed with the compound. The
kinetics of excretion in domestic animals have been partially determined.
The toxic effect of pentachlorophenol probably lies in its ability
to uncouple oxidative phosphorylation, thereby short-circuiting the energy
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metabolism of the animal. Serious skin damage and necrosis accompany
cutaneous exposure to either pentachlorophenol in petroleum solvents or
sodium pentachlorophenate powder. Conversely, pentachlorophenol powder
causes only slight skin redness in the rabbit. Cutaneous exposure of
domestic animals to pentachlorophenol should be avoided; skin damage occurs
as well as absorption through the skin which may result in systemic tox-
icity. Symptoms of severe systemic pentachlorophenol poisoning include
hyperpyrexia, depression, rapid respiration, weakness, death without strug-
gle, and rapid onset of rigor mortis following death. Autopsy results of
fatally poisoned animals have indicated pathological changes of the kid-
ney, liver, spleen, stomach, intestinal tract, respiratory tract, and
urinary bladder.
Extensive loss of wildlife, including the death of fish, frogs,
snails, and birds, has been reported following the widespread application
of sodium pentachlorophenate as a molluscicide in Surinam, South America.
The lethal effect of pentachlorophenol on snail kites (a species of bird
which feeds almost exclusively on snails) is especially noteworthy because
these animals were exposed by consuming pentachlorophenol-contaminated
snails. Substantial levels of pentachlorophenol were also noted in birds
which were not killed by the compound, indicating that contamination of
wildlife in the area was fairly widespread. The effect of the sublethal
pentachlorophenol levels found in wildlife was not determined. However,
the use of pentachlorophenol as a molluscicide on such a large scale is
hazardous to wildlife. Less toxic, more selective pesticides should be
found.
Long-term chronic effects in wild and domestic animals following
exposure to small quantities of pentachlorophenol have not been documented.
Some experiments have determined the effects of moderate pentachlorophenol
intake by domestic and experimental animals over medium lengths of time.
Pentachlorophenol was administered to sheep and calves in the form of
impregnated sawdust to simulate the ingestion of pentachlorophenol-treated
wood by farm animals. Noticeable systemic effects, including loss of body
weight and decline in general condition, were noted in sheep that were
daily force-fed pentachlorophenol at levels of 30 mg/kg body weight for 10
to 20 days. To achieve these levels of pentachlorophenol intake, animals
were force-fed with 30 g of sawdust per day. Similar systemic effects
were seen in calves fed 35 mg pentachlorophenol per kilogram body weight
daily for 10 to 20 days, which corresponded to an intake of 170 g sawdust
per day. In these experiments, systemic effects were only noticeable at
daily intake levels above 30 mg pentachlorophenol per kilogram body weight.
The question of whether lower intakes of pentachlorophenol over longer
periods may cause more subtle effects in domestic animals has not been
answered. Rats fed diets containing pentachlorophenol at levels between
50 and 200 mg/kg food had increased liver weights with concomitant in-
creases in microsomal enzyme activity, accompanied by lower hemoglobin
and hematocrit values. Furthermore, a dose-related decrease in kidney
calcium deposits occurred. The significance of these changes to the phys-
iology of rats is unknown. Although there is obvious danger of acute
systemic toxicity following absorption of large quantities of pentachlo-
rophenol, little evidence suggests that other more subtle hazards are
associated with uptake of low or chronic amounts.
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Fish and aquatic organisms remove pentachlorophenol and/or sodium
pentachlorophenate readily from surrounding water, but the route of uptake
is unclear. Following uptake, high pentachlorophenol levels have been
detected in the gills, kidneys, hepatopancreas, and gallbladder. Very
high levels in the gallbladder are particularly noteworthy. It has been
suggested that pentachlorophenol is detoxified following transfer to the
hepatopancreas and is transported partly to the gallbladder and the bile.
Many aquatic organisms, such as the short-necked clam and goldfish, readily
metabolize pentachlorophenol by conjugation to sulfate and excrete penta-
chlorophenol in a conjugated form. Following absorption of pentachloro-
phenol by goldfish, initial elimination appears to be rapid; approximately
80% of the pentachlorophenol taken in by the fish is excreted within 40 hr.
However, 20% of the compound remains in the fish for longer than 60 hr,
and its fate is unknown. In the absence of a storage mechanism in the
fish, the compound is presumably eliminated over a relatively long period.
Some investigators have suggested that the slow excretion kinetics for
goldfish may result from storage of pentachlorophenol in the gallbladder
or perhaps in the lipids.
Pentachlorophenol is toxic to fish and other aquatic organisms when
large amounts reach the receiving water. Numerous fish kills have been
reported from seepage of pentachlorophenol-contaminated effluents or from
spillage of the concentrated compound into waterways. Herbicidal and
molluscicidal uses of the compound have been hazardous to fish and inver-
tebrate populations. Aquatic species vary in their susceptibility to
pentachlorophenol toxicity. Some fish species tolerate pentachlorophenol
levels as high as 600 yg/liter, but more sensitive species perish at con-
centrations as low as 30 yg/liter. Therefore, substantial amounts should
not be allowed to reach waterways. The embryonic development of fish and
other aquatic organisms is affected at pentachlorophenol concentrations
as low as 50 yg/liter. More subtle chronic effects may occur in aquatic
communities exposed to pentachlorophenol residues. Effects on the growth
and food conversion efficiency of the sockeye salmon have been reported
at pentachlorophenol levels as low as 2 yg/liter. Eels exposed to penta-
chlorophenol and then placed in a fresh, pentachlorophenol-free medium
showed changes in a number of blood parameters and alterations in liver
enzyme activity which persisted despite the fish spending two months in
"clean" water. It is not clear whether permanent damage to enzyme sys-
tems occurred or whether low pentachlorophenol levels in the tissue during
the recovery period may have had long-term effects.
An assessment of the toxicity of a compound to aquatic organisms
must take into account environmental factors which affect its toxicity.
Water conditions such as temperature, pH, salinity, dissolved oxygen, and
hardness are known to affect the toxicity of pentachlorophenol to aquatic
organisms. The presence of other toxicants may also affect the acute
toxicity of pentachlorophenol in aqueous solutions.
Pentachlorophenol is almost certainly bioconcentrated in many aquatic
organisms. Tissue levels 100 to 1000 times the level of ambient penta
chlorophenol in water have been found in fish. The eel, a species with
a high fat content, acquires higher levels of pentachlorophenol than fish
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species with a lower fat content. It is not known whether toxicologically
significant amounts of pentachlorophenol may be accumulated by aquatic
organisms over their lifetimes, particularly following intermittent expo-
sures. Biomagnification (i.e., the presence of a substance in increasing
concentrations at higher trophic levels in the food chain) has not been
demonstrated conclusively for pentachlorophenol; however, evidence indi-
cates that pentachlorophenol may be biomagnified in aquatic ecosystems.
Model aquatic ecosystems have indicated that the mosquito fish (the high-
est trophic level in an experimental six-element food chain) accumulated
pentachlorophenol at levels 300-fold higher than the level in the ambient
environment. Other organisms in the food chain accumulated lower amounts
which corresponded roughly to their trophic level. The hazard posed by
biomagnification of pentachlorophenol in a natural aquatic system has not
been elucidated. Pentachlorophenol may also appear in aquatic organisms
as a result of degradation of hexachlorobenzene. One experiment has dem-
onstrated the netabolism of hexachlorobenzene to pentachlorophenol in
aquatic organisms, which indicates the possibility that pentachlorophenol
in water may result from detoxification of hexachlorobenzene (or perhaps
other compounds).
Fish can detect pentachlorophenol and demonstrate an avoidance reac-
tion to it when placed in a pentachlorophenol gradient. This phenomenon
is species dependent; levels of 100 yg/liter can be detected by the juve-
nile Atlantic salmon. The environmental significance of this ability is
unknown.
Pentachlorophenol can cause acute systemic toxicity in humans fol-
lowing absorption through the respiratory tract, the gastrointestinal
tract, or the skin. Minimum lethal concentrations for pentachlorophenol
in air have not been defined; however, a number of documented cases of
pentachlorophenol toxicity resulting in human death are believed to have
had a respiratory component. Severe general upper respiratory distress
usually accompanies human exposure to atmospheric pentachlorophenol; some
tolerance is found in individuals who routinely handle the material.
Despite the characteristic warning of exposure to atmospheric pentachlo-
rophenol (i.e., respiratory distress), one clear-cut case of respiratory
pentachlorophenol poisoning has been reported. The victim occupied a
house whose interior redwood siding had been improperly treated with the
preservative. Because pentachlorophenol is not likely to be present as
a dust or an aerosol, pentachlorophenol vapor was believed to be respon-
sible. The small, but substantial, vapor pressure of pentachlorophenol
may allow toxic levels of the compound to build up in hot, enclosed areas.
Studies with experimental animals as well as several reports of human
systemic toxicity following ingestion of pentachlorophenol have shown
that the compound is rapidly absorbed through the gastrointestinal tract.
Ingestion of pentachlorophenol is probably rare among humans. Only in
such exceptional circumstances as suicides or extraordinary insensitivity
is a person likely to ingest a compound of such noxious character. How-
ever, possible ingestion of small amounts of pentachlorophenol in the
diet cannot be ignored.
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Most reported cases of pentachlorophenol intoxication in hunans in-
volve direct absorption of pentachlorophenol or its sodium salt through
the skin. Absorption through the skin following contact ~av be extrerelv
rapid, with severe symptoms and death occurring after verv short (a few
minutes) exposures. The nature of the solvent in which pentachlorophenol
is dissolved apparently affects uptake and subsequent toxicity of the zz~-
pound, but no investigations of why the organic solvent affects cutaneous
absorption were found. Pentachlorophenol appears to be most toxic when
applied in petroleum solvents and is less toxic in vegetable oils. Fol-
lowing cutaneous application, pentachlorophenol in organic solvents seens
to be considerably more toxic to experimental animals than sodiun penta-
chlorophenate in aqueous solution. Repeated application of soap and water
is more effective in removing pentachlorophenol or sodiur pentachlorophe-
nate from the skin than alcohol application.
Whether pentachlorophenol is absorbed through the skin or respira-
tory tract or is ingested, it is distributed in and transported by the
blood. Pentachlorophenol apparently is not bound to the cellular constit-
uents in blood, but evidence exists that pentachlorophenol -ay bind to
plasma proteins. Studies performed with experimental animals indicate
that pentachlorophenol is present in almost all tissues within 2- hr fol-
lowing a lethal oral dose. However, the highest levels of pentachloro-
phenol in experimental animals or in lethally poisoned humans have been
found in the liver, stomach, intestines, kidney, gallbladder, blood, and
urine. The compound may be present in the kidney because of the function
of this organ in urinary excretion. Its presence in the liver -ay arise
from pentachlorophenol detoxication; high pentachlorophenol levels in the
gallbladder, stomach, and intestines indicate that it -ay be present in
gastric and biliary secretions that cause fecal excretion.
The extent to which pentachlorophenol transfers across the placenta
in mammals has not been adequately defined. Experiments have yielded re-
sults that are difficult to interpret quantitatively, and more research
in this area is warranted.
Metabolic alteration of pentachlorophenol in mammals and humans has
been studied. In mice, free pentachlorophenol and its conjugates and
tetrachlorohydroquinone and its conjugates are excreted in the urine.
Chloranil, a compound closely related to tetrachlorohydroquinone, also
has been identified in the urine of experimental animals dosed with pen-
tachlorophenol. In only one case has a pentachlorophenol conjugate, the
glucuronate, been identified in mammals. Biotransformation of pentachlo-
rophenol may take place in the liver, but no direct information is avail-
able on the tissue sites for metabolism of pentachlorophenol.
In humans and experimental animals, pentachlorophenol appears to be
excreted primarily through the urine. Although initial elimination may
be rapid, a return to background levels may take longer than one month.
There are species differences in kinetics and metabolites. Approximately
50% of the administered pentachlorophenol is excreted in the urine in 24
hr, and 70% to 85% is excreted in four days. Pentachlorophenol levels
in the urine correspond to the quantity of the compound absorbed. Thus,
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238
urinary pentachlorophenol levels have been used as a diagnostic tool in
determining pentachlorophenol exposure in huraans. In view of the data
obtained from experimental animals, a true assessment of pentachlorophe-
nol exposure should include examination of the urine for the commonly
seen metabolic products of pentachlorophenol metabolism, including penta-
chlorophenol conjugates, tetrachlorohydroquinone and its conjugates, and
chloranil. The presence of these compounds would indicate biodegradation
of pentachlorophenol in the organism. Fecal excretion also has a role in
elimination. Values ranging from 4% of the injected dose in the rabbit
to 13% in rats over a ten-day period have been reported, but this type
of information is rare. There is evidence of enterohepatic circulation.
The primary mechanism of pentachlorophenol toxicity in humans is
likely its ability to uncouple oxidative phosphorylation and to short-
circuit metabolism. An increase in cellular respiration and the generation
of considerable heat accompany the uncoupling of oxidative phosphorylation.
Effects on specific organs as a result of the disruption of normal levels
of ATP are speculative, but massive damage occurs if these vital processes
within the cell are disrupted to any large extent.
Both pentachlorophenol and sodium pentachlorophenate can cause local
inflammation on skin contact. Damage ranges from minor irritation and
redness to edema, inflammation, and necrosis of skin, depending on the
concentration of the solution and the type of carrier solvent. A serious
skin disease known as chloracne can result from long—term cutaneous con-
tact with pentachlorophenol or sodium pentachlorophenate. It is not clear
whether pentachlorophenol or impurities such as chlorodibenzo—p—dioxins
commonly found in technical-grade pentachlorophenol formulations are
responsible for chloracne in humans.
Acute systemic toxicity due to absorption of pentachlorophenol or
sodium pentachlorophenate results in major degenerative changes in vital
organs, including the gastrointestinal tract, lungs, spleen, liver, kid-
neys, and heart. Symptoms exhibited by humans acutely poisoned by penta-
chlorophenol are weight loss, general weakness, fatigue, dizziness, mental
weakness, headache, anorexia, nausea and vomiting, dyspnea, hyperpyrexia,
respiratory distress, tachycardia, hepatomegaly, profuse perspiration, and
elevated basal metabolic rate. The most common symptoms of pentachloro-
phenol intoxication are general weakness, weight loss, and profuse perspi-
ration. About 50 cases of poisoning from pentachlorophenol ingestion or
absorption have been reported and 30 resulted in death. No specific anti-
dote for the poison is known, and the deaths occurred despite conventional
supportive therapy. Infants poisoned by cutaneous contact with pentachlo-
rophenol were successfully treated with exchange transfusions. The use of
intravenous fluids to promote renal excretion may be beneficial.
Susceptibility to pentachlorophenol poisoning may depend on factors
such as the capacity of the renal system to handle the prevalent load of
pentachlorophenol and the patient's general health. The exact dosage of
pentachlorophenol required to produce illness in huraans is not known.
Symptoms occur at pentachlorophenol concentrations of 40 to 80 mg/liter
in the blood; blood levels noted in fatal cases ranged from 46 to 156
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239
mg/liter, and urine levels ranged from 28 to 520 ing/liter. The oral
lethal dose for humans has been listed as 29 mg/kg bodv veight. However
as noted before, the actual amounts required to cause systemic toxicity
probably depend on the renal competency and general health of the indi-
vidual. Another factor which may influence pentachlorophenol toxicitv i~
high ambient temperature. Most fatal cases of pentachlorophenol poisonins
resulted from exposure when ambient temperatures were high. Because the
primary effect of pentachlorophenol intoxication is hyp erpyrexia, increased
toxicity of pentachlorophenol with high ambient temperatures ma-.- be cue to
increased difficulty in dissipating excess body heat generated by the un-
coupling of oxidative phosphorylation.
Chronic pentachlorophenol poisoning of experimental animals with
extremely low doses has not been clearly demonstrated. No chronic STS-
temic disease was noted in rabbits when pentachlorophenol was applied
cutaneously at levels low enough to avoid gross skin damage. Daily sub-
cutaneous or intraperitoneal doses of pentachlorophenol to rabbits —7
cause severe symptoms and death if the doses are high enough. The amount
of pentachlorophenol necessary to cause death when it is adninistered in
small, divided doses is very similar to the minimum lethal dose for a
single administration of the compound. Renal competency may determine
the chronic levels of pentachlorophenol which may be tolerated. Thus,
cases of chronic poisoning may result not from a storage-type aecunul ation
of the compound in the system, but rather from uptake in excess of excre-
tion rate (which is determined by the ability of the renal system to handle
the prevalent load). A steady state may be reached vhen levels of penta-
chlorophenol are high enough to cause systemic intoxication. Chronic
effects from storage—type accumulation of pentachlorophenol in experimental
animals have not been demonstrated. Rats fed diets containing pentachlo-
rophenol in concentrations too low to cause severe systemic effects had
a dose—related decrease in calcium deposits in the kidney. This effect
is not well understood, and its importance to the well-being of the orga-
nism is unknown. Chronic effects from storage-type accumulation of pen-
tachlorophenol in experimental animals have not been demonstrated.
Low-dose pentachlorophenol exposure may not result in chronic effects
in humans. Although low but detectable levels of pentachlorophenol have
been found in the blood and urine of occupationally and nonoccupationally
exposed persons, no chronic effects from these prevalent levels have been
noted. Chronic exposure of persons in the wood treatment industry to
pentachlorophenol reportedly has reversible effects on kidney function.
Investigators have concluded that pentachlorophenol exposure results in
decreased creatinine clearance and phosphorus reabsorption in the kidney
but that the effect is reversible. Significant differences in blood and
urinary phosphorus levels and in creatinine clearance have been found
in wood treaters before, during, and after vacation. Such minor effects
on kidney function are probably in most cases insignificant; however,
the question warrants further study. Workers chronically exposed to
pentachlorophenol may also show a significantly higher prevalence of
gamma-mobility C-reactive protein in the sera. Although the clinical
significance of these elevated levels is not known, C-reactive protein
levels are often elevated in acute stages of inflammation or tissue dam-
age. These data have not been verified.
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Pentachlorophenol may accumulate in adipose tissue of humans. Levels
of 12 to 45 yg/kg tissue have been found in individuals not occupationally
exposed to pentachlorophenol. The levels of pentachlorophenol in fat are
likely toxicologically insignificant. Increased levels may be found in
individuals occupationally exposed to the compound. The potential for
biomagnification in human adipose tissue is an open question warranting
further investigation.
The almost ubiquitous presence of pentachlorophenol in humans may
result from the metabolism of other organochlorine compounds. For example,
pentachlorophenol has been isolated from the excreta of rats and monkeys
following administration of lindane. This finding causes question of the
tacit assumption that pentachlorophenol in human urine, serum, and tissue
results from direct exposure. In almost all cases of pentachlorophenol
poisoning in humans (fatal and nonfatal), misuse of the compound is para-
mount. Industrial safety records for pentachlorophenol handling are excel-
lent, but deaths of casual or inexperienced users and other nonindustrial
fatalities resulting from inappropriate use of the compound (e.g., death
of infants in a St. Louis nursery where pentachlorophenol was inappropri-
ately used in laundry facilities) have been reported. Adequate protection
from cutaneous or respiratory contact with pentachlorophenol should prevent
most cases of human systemic intoxication. When explicit safety precau-
tions are not noted, common sense would indicate that exposure to the
compound should be minimized.
Market basket studies conducted by the U.S. Food and Drug Administra-
tion have shown that some portion of the nation's population is exposed to
low levels of pentachlorophenol through food consumption. The sources of
the residues in food are not known, and the hazards associated with con-
sumption of these small quantities of pentachlorophenol remain speculative.
Pentachlorophenol does not promote tumor formation in mice following
oral administration or following cutaneous application of a single initiat-
ing dose of dimethylbenzanthracene. Other chlorophenol compounds and phe-
nol possess tumor-promoting activity following cutaneous application of
dimethylbenzanthracene. Also, pentachlorophenol did not exhibit mutagenic
properties when it was tested in a microbiological system, in a mammalian
test system, and in the fruit fly (Drosophila melanogaster') . Pentachloro-
phenol does not appear to be teratogenic but is fetotoxic. Delayed devel-
opment has been observed when high pentachlorophenol dosages are administered
to the maternal rat. However, fetotoxic effects likely result from a direct
effect on the maternal rat. The most prominent effect of pentachlorophenol
on the mammalian system is hyperpyrexia, and this alone may cause the
fetotoxicity.
Monitoring data for levels of pentachlorophenol in the atmosphere
are unavailable, but circumstantial evidence indicates that pentachloro-
phenol may be present in the atmosphere. Levels of pentachlorophenol in
rainwater and snow samples taken from the Mauna Kea Summit in Hawaii indi-
cated that pentachlorophenol is likely present in the atmosphere either
as a vapor or as an occlusion on dust particles and is removed from the
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241
atmosphere by washout. Significant amounts of pentachlorophenol are dis-
charged in gaseous and particulate forms from manufacturers of pentachlo-
rophenol. Detailed information on pentachlorophenol levels in the
atmosphere surrounding such plants is not available.
Monitoring data on the presence of pentachlorophenol in the aquatic
environment are scant. There have been numerous reports of fish kills
following industrial accidents, including spillage and seepage of concen-
trated pentachlorophenol. Deleterious effects on aquatic organisms follow-
ing the widespread distribution of pentachlorophenol as a molluscicide or
algicide have also been reported. However, these lethal occurrences are
usually associated with the presence of high levels of pentachlorophenol
in water. Documentation of low-level pentachlorophenol contamination of
water is not available. Measurable amounts of pentachlorophenol are pres-
ent in treated and untreated wastewaters from wood treatment plants. Pen-
tachlorophenol has also been detected in storm water draining industrial
sites where treated lumber has been stored, and its presence has been con-
firmed in municipal sewage. Furthermore, measurable pentachlorophenol
levels have been detected in the Willamette River in Oregon and in the
drinking water supplies of Tallahassee, Florida, and Corvallis, Oregon.
Contamination sources could include leaching from preservative-treated
items; use of pentachlorophenol as a slimicide, as an algicide, or, more
infrequently, as a herbicide; inadequate treatment of sewage containing
pentachlorophenol; synthesis during drinking water or wastewater chlori-
nation procedures; and synthesis from other related organic compounds
such as hexachlorobenzene.
The persistence of pentachlorophenol in aquatic environments depends
on a number of environmental variables; the interrelationships have not
been fully characterized. Pentachlorophenol may be dissipated from water
by volatilization, photodecomposition, sorption, or biodegradation. The
primary mode of removal is likely biodegradation. Decomposition of penta-
chlorophenol in aqueous solution has been demonstrated under laboratory
conditions in the presence of suitably activated microbial populations.
In the laboratory, microorganisms contained in activated sludge derived
from sewage treatment plants exposed to pentachlorophenol are capable of
degrading the compound. However, the distribution of these microorganisms
in the environment is unknown. Under specified conditions, pentachloro-
phenol levels in water declined to negligible amounts in 48 hr; other
experiments indicated that substantial amounts of pentachlorophenol may
remain in a laboratory system for more than 120 days. Thus, depending
on environmental conditions, pentachlorophenol may degrade rapidly and
pose little or no environmental hazard, or it may have marked longevity
and 1-' ^eby pose a potential hazard of indeterminate proportions.
Ambient levels of pentachlorophenol in soil are not available. Pos-
sible sources of contamination include direct application as a herbicide
or desiccant, washout from the atmosphere, and leaching from preservative
treated wood. Mobility and persistence of pentachlorophenol depend on the
physical and chemical characteristics of the soil as well as on the pre-
vailing microbial population. Pentachlorophenol is strongly sorbed in
most soils, and movement through the soil is likely to be negligible. A
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242
large number of environmental parameters such as temperature; pH; moisture;
organic matter, clay mineral, and free iron contents; sorption character-
istics; cation-exchange capacity; and microbiological composition affect
the persistence of pentachlorophenol in soils. Microbiological activity
plays a primary role in the degradation of pentachlorophenol in soil, and
persistence ranges from 21 to 200 days, depending on specific conditions
at the site. Apparently, acclimated microbial populations (those previ-
ously exposed to pentachlorophenol) facilitate pentachlorophenol decompo-
sition in soil. Under conditions unfavorable for bacterial growth,
pentachlorophenol degradation is extremely slow.
Pentachlorophenol is considered to be a refractory compound of the
chlorophenol family. Although microbial populations capable of rapid
pentachlorophenol degradation have been isolated, gradual acclimation of
the bacteria to increasing pentachlorophenol levels is required to produce
strains which optimally degrade pentachlorophenol. In many cases where
rapid pentachlorophenol degradation was noted without initial acclimation
of the bacteria to pentachlorophenol, the initial microbial inoculum was
frequently derived from areas where pentachlorophenol had been used for a
considerable time. In the presence of alternative substrates, pentachloro-
phenol-degrading bacteria may not be optimally efficient. Other bacterial
populations are capable of preferentially degrading pentachlorophenol in
the presence of an alternative carbon source. It is not known whether
these bacteria possess qualities which allow them to compete effectively
in a mixed population. Data indicate that pentachlorophenol-degrading
bacteria are present in soil surrounding pentachlorophenol-treated wood.
In general, pentachlorophenol is moderately stable in preservative-treated
wood and dissipates slowly as a result of biodegradation and leaching. The
environmental hazard of properly treated wood is probably minimal. Slow
contamination, when it occurs, is likely confined to very localized areas
surrounding the treated wood, and the pentachlorophenol which reaches the
soil is degraded sufficiently rapidly to prevent a hazard to plant and
animal life. However, in light of the extremely high toxicity of penta-
chlorophenol to aquatic organisms and possible biomagnification, the use
of pentachlorophenol-treated wood in or around aquatic environments should
be carefully regulated.
Evidence exists that pentachlorophenol-containing effluent can be
degraded in an aeration lagoon. Based on one laboratory study, the aera-
tion lagoon apparently provides an efficient method for the secondary
treatment of pentachlorophenol-containing wastewater. In the laboratory,
activated sludge populations are capable of degrading pentachlorophenol,
but retention times are quite long because pentachlorophenol is a rela-
tively stable molecule. The efficiency of these processes in any given
sewage treatment plant must be assessed on an individual basis. When
adequate precautions are taken and retention times are long enough, ade-
quate biological elimination of pentachlorophenol from wastewater can
likely be achieved by biodegradation. Of more serious concern is the
disruption of normal sewage treatment processes when the compound is not
a regular component of the influent wastewater.
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243
D.I.2 CONCLUSIONS
1. The most widely used, effective technique for analysis of penta-
chlorophenol in many sample types is gas-liquid chromatography.
2. Pentachlorophenol is extremely toxic to almost all forms of bacteria,
algae, and fungi and is widely used as an antimicrobial agent and
as a preservative.
3. Pentachlorophenol is rapidly absorbed by the roots and foliage of
vascular plants but does not translocate readily to other plant
parts.
4. Vascular plants (terrestrial and aquatic) are extremely sensitive
to the toxic effect of pentachlorophenol, and contact with crops or
ornamental plants should be scrupulously avoided.
5. Exposure of wild or domestic animals to concentrated pentachloro-
phenol solutions or their constant cutaneous exposure to pentachlo-
rophenol-treated wood may result in illness or death.
6. Current data are insufficient to evaluate chronic long-term effects
of pentachlorophenol-treated wood on livestock. Preservative-treated
wood probably poses no serious hazard to domestic animals if the wood
has been properly treated and if animals do not have constant cutan-
eous contact with the treated wood.
7. The toxic effect of pentachlorophenol probably lies in its ability
to uncouple oxidative phosphorylation in living organisms, thereby
short-circuiting metabolism.
8. Pentachlorophenol biotransformation in animals and humans probably
involves the formation of pentachlorophenol conjugates (including
glucuronides) , tetrachlorohydroquinone, tetrachlorohydroquinone
conjugates, and chloranil.
9. Extensive loss of wildlife has been reported following the applica-
tion of large amounts of pentachlorophenol as a molluscicide; such
usage is not recommended.
10. Pentachlorophenol is extremely toxic to aquatic organisms;^sensitive
species of fish perish at concentrations as low as 30 yg/liter.
Measurable sublethal effects from chronic exposure have been docu-
mented at concentrations less than 2 yg/liter.
11. Following uptake of pentachlorophenol by fish, initial elimination
is very rapid. However, approximately 20% of the pentachlorophenol
absorbed may remain in fish tissue for an extended time; storage in
fat may account for this phenomenon.
12. Pentachlorophenol is almost certainly bioconcentrated in many aquatic
organisms; tissue levels 100 to 1000 times the ambient level of
pentachlorophenol in water have been found in fish.
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244
13. Pentachlorophenol may be subject to biomagnification in aquatic eco-
systems (i.e., found in increasing concentrations at higher trophic
levels in the food chain).
14. In view of its high toxicity to aquatic animals and the likelihood
of bioconcentration, low limits for pentachlorophenol residues in
waterways should be considered.
15. Appearance of pentachlorophenol in aquatic organisms and experimental
mammals following absorption of hexachlorobenzene has been documented.
16. Nearly all reported cases of severe systemic pentachlorophenol poison-
ing in humans involved either poor hygiene or improper usage of the
compound.
17- Following uptake of pentachlorophenol by humans or experimental ani-
mals, high levels are found in the liver, stomach, intestines, kidney,
gallbladder, blood, and urine, with the highest levels in the gall-
bladder. Possibly, the gallbladder could serve as an indicator organ
in establishing pentachlorophenol exposure.
18. Placental transfer of pentachlorophenol is controversial.
19. Data from experimental animals indicate that a true assessment of
human exposure to pentachlorophenol should include examination of
the urine for the commonly seen metabolic products of pentachloro-
phenol metabolism (pentachlorophenol conjugates, tetrachlorohydroqui-
none, tetrachlorohydroquinone conjugates, and chloranil).
20. Although initial elimination may be rapid following human exposure
to pentachlorophenol, a return to background levels may take more
than a month. Inadequate experimental methods preclude definitive
conclusions, and carefully controlled studies are needed.
21. Low, but detectable, levels of pentachlorophenol have been found in
blood, urine, and fat of nonoccupationally exposed persons, but
chronic effects from these prevalent levels have not been demonstrated.
22. Minor effects on kidney function and a significantly higher preva-
lence of gamma-mobility C-reactive protein in the sera have been
associated with chronic pentachlorophenol exposure in workers in
the wood treatment industry, but the significance of these effects
to the health of the individuals is speculative.
23. Available data indicate that pentachlorophenol does not possess
tumorigenic, mutagenic, or teratogenic properties.
24. Circumstantial evidence indicates that pentachlorophenol is present
in the atmosphere.
25. Low levels of pentachlorophenol have been detected in river water
and in several municipal water supplies; the health hazard posed by
these levels is unknown.
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245
26. Pentachlorophenol is rapidly dissipated in the aquatic environment
when suitably acclimated microbial populations are present; under
less than ideal conditions, however, pentachlorophenol persistence
may be considerably extended.
27. Pentachlorophenol is strongly sorbed in most soils, and movement
through the soil profile is unlikely; persistence ranges from 21
to 200 days, depending on specific conditions at the site.
28. Acclimated microbial populations (those previously exposed to penta-
chlorophenol) facilitate decomposition in soil. Under conditions
where bacterial growth is not favored, pentachlorophenol degradation
is extremely slow.
29. The environmental hazard of wood properly treated with pentachloro-
phenol is probably minimal in the terrestrial environment.
30. The use of pentachlorophenol or pentachlorophenol-treated wood in
or around aquatic environments should be carefully examined because
of its high toxicity to aquatic organisms and possible biomagnifi-
cation in aquatic ecosystems.
31. Pentachlorophenol can be readily degraded in aeration lagoons or
activated sludge when suitably acclimated microorganisms are present
and retention times are of sufficient length.
32. The presence of low quantities of pentachlorophenol in foods con-
sumed by humans has been reported, but health hazards associated
with consumption of foods containing low levels of pentachlorophenol
have not been documented.
-------
D.2 CHEMICAL AND PHYSICAL PROPERTIES AND ANALYSIS
D.2.1 PHYSICAL PROPERTIES
In the pure state, pentachlorophenol is a white, needlelike, crys-
talline solid. Because it is practically insoluble in water, its sodium
salt, which is readily soluble in water, is substituted for many practi-
cal uses. Some physical properties of pentachlorophenol are listed in
Table A.2.1.
D.2.2 MANUFACTURE
Pentachlorophenol is synthesized commercially by the direct chlo-
rination of phenol. Chlorination proceeds stepwise, and catalysts such
as FeCl3, A1C13, and SbCl3 are used in concentrations of 0.05% to 1.0%.
Usually, the reaction is carried out in the absence of solvents (with
direct addition of gaseous chlorine to molten phenol), but carbon tetra-
chloride, acetic acid, and water have been used as diluents. In industry,
the starting material for pentachlorophenol production may be a mixture
of various chlorophenol isomers if these compounds are readily available
(Doedens, 1963). Pentachlorophenol may also be produced through hydrol-
ysis of hexachlorobenzene, but this method is less popular than the
direct chlorination technique.
D.2.3 USES
Pentachlorophenol and sodium pentachlorophenate are used extensively
as broad-spectrum biocides. In 1972, annual production in the United
States exceeded 50,000,000 Ib (23,000,000 kg) (Anonymous, 1972). Growth
was projected at about 4% per annum after 1972. Estimated production of
pentachlorophenol and sodium pentachlorophenate in 1976 was 56,000,000 Ib
(25,400,000 kg).
Pentachlorophenol (or sodium pentachlorophenate) has been used as a
wood preservative to control mold and termite infestations (Fuller et al.,
1977), as a weedicide or preharvest desiccant, as an algicide, as a
molluscicide for the eradication of the snail which serves as an inter-
mediate host for the schistosomes in humans, and in food processing
plants and pulp mills for the control of slime and mold. Pentachloro-
phenol and sodium pentachlorophenate also have been used as fungicides
and/or bactericides in the processing of cellulosic products, starches,
adhesives, paints, leathers, oils, rubber, textiles, and wooden crates
used for packaging raw agricultural products. Obviously, a product with
such widespread and varied uses poses a serious potential for environ-
mental contamination (Bevenue and Beckman, 1967).
D.2.4 CHEMICAL REACTIVITY
Pentachlorophenol is quite stable; it does not decompose when
heated at temperatures up to its boiling point for extended periods.
Pure pentachlorophenol is considered to be rather inert chemically
246
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247
(Bevenue and Beckman, 1967). The chlorinated ring structure tends to
impart stability, but the polar hydroxyl group facilitates biological
degradation (Renberg, 1974). Pentachlorophenol is not subject to the
easy oxidative coupling or electrophilic substitution reactions common
to most phenols. Any monovalent alkali metal salt of pentachlorophenol
is very soluble in water, but the protonated (phenolic) form is virtu-
ally insoluble. Hence, transport of pentachlorophenol in water depends
largely on the pH of the environment.
Pentachlorophenol is volatile enough to be steam distilled — a
property that can be exploited by the analyst. If a closed system is
not used when environmental samples are heated, recoveries are poor
(Bevenue and Beckman, 1967). By analogy to other chlorinated organic
compounds with low vapor pressures, volatility may cause significant
losses of pentachlorophenol from soils (Briggs, 1975).
D.2.5 TRANSPORT AND TRANSFORMATION IN THE ENVIRONMENT
The transport and transformation mechanisms of pentachlorophenol
in air, soil, and aquatic environments are discussed fully in Section
D.7. These mechanisms are summarized in this section to give a per-
spective on the possible relationships of the physical and chemical
properties of the compound to its environmental interactions.
D.2.5.1 Air
Pentachlorophenol can enter the atmosphere by several routes. Even
though its vapor pressure is low, a finite amount will vaporize. In the
past, use of pentachlorophenol as a spray-on herbicide released the mate-
rial directly into the air. Also, depending on the solvent system and
conditions, pentachlorophenol may recrystallize on the surface of treated
wood (referred to as blooming), and these small crystals can then be
brushed off into the ambient air. The significance of aciy of these
routes is determined by the specific circumstances. Volatilization is
likely the major mechanism for dispersal of the compound into the atmos-
phere; however, monitoring data are lacking.
D.2.5.2 Aquatic Environment
In the aquatic environment, pentachlorophenol may be in dissolved
form, associated with suspended matter or bottom sediments, or absorbed
by organisms. Metal salts of the compound have much greater water solu-
bility and therefore would exist primarily in the dissolved form. The
tendency of pentachlorophenol to ionize depends on the pH of the system.
It is nonionized in aqueous solutions with pH lower than 5 and becomes
increasingly dissociated as the pH rises. The degree of dissociation
could determine the extent of sorption of colloids present in aquatic
systems; however, specific information is not available. Hydrological
factors such as current patterns and mixing as well as sorption, degrada-
tion, and migration of organisms affect the movement of the chemical.
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248
There is limited evidence of microbiological degradation of penta-
chlorophenol in aquatic environments. Photodecomposition and volatili-
zation from water also occur. Detailed discussions of these phenomena
are found in Section D.7.
D.2.5.3 Soils
One of the most important environmental aspects of a synthetic
organic chemical is its interaction with the soil. Soil is the ulti-
mate absorber and purifier of many of the most toxic chemicals. In the
soil, pentachlorophenol is affected by many complex factors; many de-
tails of its behavior are unknown or have not been verified (Bevenue
and Beckman, 1967). Greenhouse studies of soils treated with sodium
pentachlorophenate showed that the toxicity of the compound to sweet
corn and cucumber decreased with time; toxicity was greatest at higher
(approximately 45°C) temperatures (Bevenue and Beckman, 1967). The
sodium salt was stable in air-dried soil; it persisted for two months
in soil with a moderate moisture content and for only one month is water-
saturated soil. It seemed to be more stable in heavy-clay soils than
in sandy soils (Bevenue and Beckman, 1967).
Hilton and Yuen (1963) studied the adsorption behavior of penta-
chlorophenol in several Hawaiian soils growing sugar cane. They compared
its adsorption with that of a variety of substituted urea herbicides —
linuron [3-(3,4-dichlorophenyl)-l-methoxy-l-methylurea], diuron [3-(3,4-
dichlorophenyl)-l,l-dimethylurea], and monuron [3-(p-chlorophenyl)-l,l-
dimethylurea] — and with substituted triazine herbicides — atrazine
[2-chloro-4-ethylamino-6-(isopropylamino)-s-triazine] and simazine [2-
chloro-4,6-bis(ethylamino)-s-triazine]. Adsorption of pentachlorophenol
was the highest of all the compounds studied. A study with ten soils
showed no relationship between adsorption and soil pH. Good weed control
is achieved only in soils with low adsorptivity. Excessive rates of
application (up to 500 kg/ha) provided only slightly better weed control
than 50 kg/ha. The steep slopes of the adsorption isotherms for penta-
chlorophenol indicate that large increases in pentachlorophenol applica-
tion are required to produce a significant increase in the soil solution
concentration of pentachlorophenol.
Dobrovolny and Raskins (1953) studied the effects of different soils
on adsorption of dilute concentrations of sodium pentachlorophenate.
Greater depth of the mud layer in proportion to depth of the water layer
produced a more rapid decrease in the sodium pentachlorophenate content
of the water layer. As expected, sand did not adsorb sodium pentachloro-
phenate. The nature of the chemistry between the sodium pentachloro-
phenate and the clay or silt in the sediments was not investigated.
Choi and Aomine (1972, 1974a, 1974Z?) have studied the interactions
of pentachlorophenol and soil extensively. Adsorption of pentachloro-
phenol at various concentrations was studied in several different soils
(Choi and Aomine, 1972). After adsorption equilibrium was attained, the
concentration of pentachlorophenol in the supernatant solution was
measured by the 4-aminoantipyrine method. In addition, a bioassay was
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249
conducted with wheat seedlings to measure the inhibitory rate of L50
defined as:
length of untreated seedlings in control plot -
length of pentachlorophenol-treated seedlings
length of untreated seedlings X
The L50 represents the pentachlorophenol concentration at which the
length of treated seedlings is 50% of that of the untreated seedlings;
this value is determined by graphing seedling length against concentra-
tion of pentachlorophenol. Adsorption and/or precipitation of penta-
chlorophenol occurred to some extent in all soils tested. The bioassay
revealed that inhibition of the wheat seedlings was greater for the soil
suspension than for the supernatant aqueous solution above it; however,
the inhibitory rate of the soil suspension was less than that of the
standard pentachlorophenol solution. These findings indicate that ad-
sorbed and/or precipitated pentachlorophenol retained some toxicity to
the plant.
Choi and Aomine (1974a) also studied adsorption behavior by using
13 soil samples which had various clay mineral species, organic matter
content, and pH and seven different concentrations of pentachlorophenol
ranging from 12.5 to 500 mg/liter. They concluded that adsorption
behavior depends primarily on the pH of the system; the more acid the
soil, the more complete is the "apparent adsorption" of pentachloro-
phenol. Different mechanisms of adsorption dominate at different pH
values. In acid clays, "apparent adsorption" involves adsorption on
colloids and precipitation in the micelle and in the external liquid
phase. Organic matter content of the soil is important to "apparent
adsorption" of pentachlorophenol at all pH values. At different pH
values, comparisons of untreated soil and soil oxidized with hydrogen
peroxide (H202) to remove organic matter showed that humus-containing
soil always adsorbed more pentachlorophenol than H202-treated soil. The
investigators assumed that H202 oxidation and extraction with an organic
solvent removed only organic matter and that this did not change the
structure or adsorption characteristics of the inorganic fraction remain-
ing; however, they realized that these assumptions probably were incorrect.
Later investigations led to the conclusion that adsorption of pentachloro-
phenol by humus is important when the concentration of pentachlorophenol
is low (i.e., when pentachlorophenol is adsorbed largely in the undisso-
ciated state). At higher concentrations of pentachlorophenol, the in-
organic fractions become more important.
D.2.5.3.1 Effect of Temperature on Pentachlorophenol Adsorption
by Soil — Choi and Aomine (1974Z?) studied the effects of temperature on
adsorption of pentachlorophenol by soil. Four allophanic soils with pH
adjusted to 5.6 by addition of NaOH or HC1 were used to measure the
adsorption of pentachlorophenol at 4°C and 35°C. Three soils showed a
significant increase in pentachlorophenol adsorption at higher tempera-
tures, but the fourth soil showed a decrease. The authors explained
the results on the basis of differences between the soils. They assumed
that andosols (molar Si02/A103 ratio of approximately 1) chiefly adsorbed
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250
pentachlorophenol as anions and that the major factor influencing penta-
chlorophenol adsorption by the one soil showing a decrease with increas-
ing temperature (molar Si02/A103 ratio of about 2) was a van der Waals'
force.
D.2.5.3.2 Effect of Anions on Pentachlorophenol Adsorption by Soil —
Chcd and Aomine (1974a) studied pentachlorophenol adsorption in three dif-
ferent soils in the presence of chloride and sulfate ions. They adjusted
5 g of air-dried soil to pH 5.6 and added 60 mg/liter pentachlorophenol
solution to the soil samples. Because the pH of the soil suspension was
lowered by adding sodium salts (the counterion for the chloride and sul-
fate), the amount of NaOH needed to maintain the pH at 5.6 increased with
increasing concentrations of added salts. Total volume of liquid was ad-
justed to 50 ml. At lower salt concentrations, more pentachlorophenol
was adsorbed by the soil samples. The allophanic soils showed greater
adsorption of pentachlorophenol in the presence of NaCl than in the pres-
ence of Na2SOA, but the soil with a higher Si02/A103 ratio (approximately
2) did not exhibit this trend. These results indicate competition between
the inorganic anions and the pentachlorophenol anions for adsorption sites
on the soil colloid. As would be expected, sulfate ions are able to com-
pete with pentachlorophenol for allophanic adsorption sites more effec-
tively than are chloride ions.
D.2.5.3.3 Influence of Ions on the Allophane Surface on Pentachloro-
phenol Adsorption — Allophanic clay separated from soil was used to study
the effect of surface charge on pentachlorophenol adsorption. Choi and
Aomine (19742?) treated clay samples either with a 1 N sodium acetate
buffer solution at pH 3.5 or with 2% Na2C03. The Na2C03 treatment was
more effective in reducing surface acidity than was the acetate buffer
treatment, and sodium acetate—treated clay displayed more positive charge
than Na2C03-treated clay (Figure D.2.1). The adsorption of pentachloro-
phenol on soil apparently involved anion-exchange reactions as well as
physical adsorption due to van der Waals1 forces.
Pentachlorophenol mixed with layered silicate clay minerals such as
illite, montmorillonite, and kaolinite sublimed at about 200°C. Penta-
chlorophenol mixed with or adsorbed on allophane did not sublime at 200°C
but pyrolized between 250°C and 500°C, showing a strong exothermic reac-
tion (Choi and Aomine, 19742?).
D.2.6 ANALYTICAL METHODS
In determining pentachlorophenol in soil, water, or biological
materials, the validity of results is assured only when the sample is
representative and when the pentachlorophenol in the sample is identified
and measured accurately. In complex samples such as soil, water, and
sediments, the investigator must consider the unknown or complex rela-
tionships affecting representative sampling. Compromise must often be
reached between the best method of sampling and the funding available.
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251
ORNL-DWG 78-10539
g _
n: ^
i- o>
z E
80
O x
tn o
§1
a- w
CD °-
70
60
• Na2C03-TREATED
O NoOAc-TREATED
6.0
6.5
PH
Figure D.2.1. Effect of pH on the adsorption of pentachlorophenol
by isolated allophanes. Source: Adapted from Choi and Aomine, 1974&,
Figure 5, p. 377- Reprinted by permission of the publisher.
Given a representative sample, the performance of an analytical
method depends on the quantitative extraction of pentachlorophenol and
its accurate measurement and identification. The analyst must be care-
ful that the method of determining extraction efficiency can be extrap-
olated to environmental samples and can provide uniformly quantitative
extraction from a variety of samples. For water samples, pentachloro-
phenol distribution between extractant and water is important. For soil
and sediment samples, the removal of pesticides from sorption sites is
necessary (Chesters, Pionke, and Daniel, 1974). In biological tissues,
separation from lipids must be achieved (Renberg, 1974). Also, because
pentachlorophenol residues are found in a number of samples, including
water, the analyst must be careful to exclude the possibility of sample
or glassware contamination, especially when working with low-level samples,
The actual method of analysis must be sensitive enough to detect
quantities of pentachlorophenol present and not be subject to inter-
ference from other compounds. Some methods (e.g., ultraviolet) require
"cleaner" extracts and more elaborate cleanup prior to final determina-
tion. Gas-liquid chromatography has inherently great potential for
separation of compounds so that rigorous cleanups are not necessary.
For a detailed review of many other specific factors to be considered in
evaluating analytical methods, see Chesters, Pionke, and Daniel (1974).
Many methods of qualitative and quantitative analysis have been
developed for pentachlorophenol (Tables D.2.1 and D.2.2). Samples are
sometimes expected to contain pentachlorophenol and no chemical analogs;
-------
TABLE D.2.1. METHODS OK DETERMINATION OF I'ENTACHLOROl'IIKNOL IN SEVEKAL SAMPLE MATERIALS
Sampli
Isolation mathod
Analytical mothod
and stnsii IvUy
KomnrkH
Urine
Human adipose
tissue*
Urine, blood,
and air
Urine
Natural latex
Natural watar
Natural watar
Wood
Wood
Toy paints
Bxtraotad with petroleum athar;
reextracted with NnOH and
actdlflad
Extracted NaOH aolution with
haxanei aotdifladi extracted
with aehar: othylated with
diaioathanei pentaahloro-
phanyl ethyl athar sepa-
ratad from hexaahlorophene
on a silica gal column
Air aamplai collected with
mldgat Impingari ualng
alkaline watar or lao-
octana
Addad NaOH| axtraotad with
haxanai acldlfladi axtractad
with haxana
Coagulatad with acatlc ncld|
axtraotad with aaatona
Acldlflad and axtractad Into
chloroform
Oxidliad with chlorine dloxlda
Extracted with acatona
Turbidimetrlcj 5 mg/llu-r
Elactron-cnptura gas chromatog-
raphy | 3 ug/kg
Hup I (I Hcunnltig, roiiLlin'
mo I hod
Method ro(|ulri'H nlxjut 200 MIR
I In mi I1
El«ctron-cnpiuro HUH chromatog-
raphy
Blactron-capture gag chromatog-
raphyi 2 |jg/l
Thln-layar chromatography with
CuSOk-pyrldlna spray; 10
mg/g rubber
Colorlmetrlc ualng methylene
blue or aafranlna 0[ 3
mg/llter
Ultraviolet ratio apectrometry;
2 Mg/llter
Electron probe microanalyaea;
O.U
Microacopy; 0.022X
Flame-ionlcatlon gaa chroma-
tography with danayl chlo-
ride derivatlcation; gaa
chromatographyi 1 mg/llter;
thin-layer chromatography,
A mg/llter
Air Hfimpllng procedure In-
adequately (Icucrlbod
Seven ulkyl othars of pi-ntn-
chlorophenol used; nevornl
dllTcrcnl (tolutniiH UHt'd In
dotort Ion
SumlquQiitltat tvo, rupicl
mothod
Hard water or wntur contnln-
LtiK Iron or copper yields
Interfering preclpltatea
Other phenols do not lnu>r-
fere at choaen wavelength
Determined distribution of
pentachlorophenol In wood
Determined distribution of
pentachlorophenol In wood
Minimum background obtained
by acetone extraction
Sourep
(loinHlork, Conmtuck,
nnd lUlluon,
Sluiflk, I'J/'J
CnHnret I ct ill . ,
Crnnmur and Prc.ii I ,
I 970
Dnvli'H find
TluirutHlnghnm, I96B
HuHklnH, 1951
Fountains at fll.,
1975
Rosch and Arganbright,
1971
RuMch and Arganbright,
1971
van Langaveld, 1975
Oi
N>
(continued)
-------
TABLE D.2.1 (continued)
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Source
Water and eewage
effluente
Soil, water, and
fieh
Biological tieeue
and water
Blood, urine,
tissue, and
clothing
Human blood
Human urine
Biological
samples
Extracted with bencene, fol-
lowed by K|CO§ solution;
acetylatad and extracted
with hexane
For aoil and fiah, extracted
With KOH| acidified)
extracted with toluene
Acidified) extracted with
hexane) reextractad with
borax solution
Extracted with ethyl ether;
extracted ather solution
with 5X NnOll; acid I find;
extracted with benrone
Acidified and extracted with
bencene
Acldlflod and extracted with
petroleum ether
Acidified; extracted with othyl
ether; chroma tugrnphoil on
Cellta-lliBOi, column; extracted
with sodium pyrophonphuto
Electron-capture gas chromatog-
raphyi 0.01 ng/liter
Electron-capture gao chromatog-
raphy of methyl eater; Hoil,
0.5 n«/kg; water, 0.01 |ig/kg;
flHh, 0.5 ng/kg
Electron-capture gas chronwtog-
rtiphy of othyl ethor; tissue,
mirrogrnm per gram range;
water, 0.01 |ig/lltar
Hluctron-capture gau rl\romntog-
rapliyi 0.01 mg/lltcr or 0.01
HK/B
KluiiLran-capturu gas chrnmntog-
raphy of methyl other; 20
HR/1 Iti-r
KlocLron-i'upturo gnu chromatog-
rapliy; pd-ngram to nauogram
range
I'npur c'hrum/itugrapliy foj lowiul
by uv tiporl roHcopy; r>
Acetylation In K,C09 reduced
interferencos
Trlmethylsilyl other pre-
pared for miiHH Hpec-tro-
ucopy for confirmation
Organochlor Ine InHect Ic HUM
did not Interfere
No liar kg round Interf
l.aliorIOIIM pio
Clmu and Coburn, 197A
Stark,
Kiull. Ing, 19/0
Harlhol ot al., 1969
Hevenue ot a 1., !9hH
llevenue el a I. , 19(>0
Krne, 19')H
N)
-------
TABLE D.2.2. METHODS OF DETERMINATION OK PENTACIILOROPIIENOI. IN SEVERAL SAMPLE MATERIALS CONTAINING OTHER PHENOLS
Sample
Isolation method
Analytical method
and sensitivity
Remarks
Urine
Natural water
Biological tissues
and natural water
Wood
Pish tissue, soil,
and natural water
Fats, oils, waxes,
and commercial
food-grade
fatty acids
Biological tissues
Acidified and extracted with
petroleum ether
Acidified and extracted with
petroleum ether
Steam distillation into NaOH
Acetic acld/methanol extrac-
tion and adsorption on Bio-
Rad AG2-X8 resin
Purification by binding acidic
substances to anion exchanger
Acidified; extracted with petro-
leum ether; extracted with
NaOH; acidified and extracted
with chloroform
Steam distillation and extrac-
tion with pentane or toluene
Acidified and extracted with
isopropanol/hexane
GIIH chromatography—mass spectrom-
utry; picogram to nanogram range
Two-directional thin-layer chroma-
tography with 4-amlnoanl Ipyr Ine
or silver nitrate spray; 0,1 ng
using HI.Ivor nitrate; 0.5 UK
using 4-amlnoantIpyrlne
Chromatography on Amberllte XAD-7
rcsln UHlng high-pressure liquid
chromatography with uv detector
Colorlraetrlc nitric acid oxidation;
0.01 mg
Colorimetrlc 4-amlnoanllpyrlne; 2
l'g/8
Thln-luyer chromatography after
dansyl chloride spray
Electron-capture gas chromalograpliy
(derlvatlzed); 0.3 ug/g for fish;
1.5 Mg/Hter for water; 1.5 yg/g
for soil
Electron-capture gas chromatography;
0.5 pg/g
Electron-capture gaa rhromatography
ethyl ether; 10 ng/g for wood or
litter extracts; 1.0 ng/g for fat;
0.1 ng/g for muscle
Gas-liquid chromatography of acetate;
mlcrogram per gram range
'IVt r;ii'liloror.'it IT ho I ;iml tot ra-
i*l» I orohvdroqti I HOIK* a I so ass.'ivfd
Spt'H fir for Hi loropht'iml.-;; 1 J i t Ir
or no Int ITfiTi'in'c f roni I iiorf,.'in i r
fompounds, color, or IurbId 11v;
2,/f ,6- ;ni-( r Irhlnroplicnol ,
2, 'i-il I ch i or up ho no 1 t mul "i~c\i I tu'ti-
piuMio I -i I HO ussnyi'tl
HromopluMio IK, ch J oropiit'iio I s , iiH-t hy I -
phono 1 M , iind n I L ropln-no I s .-u-pa-
r^tt'tl from pt*ntt*jrh Jorophfiio 1
Ot her t'li 1 uropht'iio IH .'in.'i I yxcd
2 , i,'?, 6-Ti't riich 1 orophono 1 .•( I scj
.is saved
2-Chlorophi'nol , 'i-rh lurciphi'iml ,
2,4-tl Irhloriiplicnol , 't./t-d Irhlii-
rophuno 1 , 2, A-5-1 r I ch I orcphiMH) I ,
pi-n t ach I ornplu'no I , i-c!iloru-
plit-nol, and phenol all a.ssayi'd
Other chlorophcnols also assayed
2,3,A,6-Tetrachlorophenol aim:
assayed
2 , 3, It, b-Te t rach lo roan 1 so I e, pent a -
chloroanl.sole, and the corre-
spond Ing chloroplienoln also
assayed
ChlorohydroxyhIphenyl also assayed
Klklu ot al,,
IV7 )
1'rltx .nid Wi I I !•,,
I«>/ \
l)c I I'liinann atul
Scll.lIlT, I'
-------
255
methods for this type of sample are usually less sensitive and specific
but more convenient than those used for residue analysis. The follow-
ing publications were judged to present the best methods of analysis of
those reviewed: Bevenue et al. (1968); Cranmer and Freal (1970); Rudling
(1970); Buhler, Rasmusson, and Nakaue (1973); Frei-Hausler, Frei, and
Hutzinger (1973); Renberg (1974); Zitko, Hutzinger, and Choi (1974).
Colorimetric and oxidation methods of analysis are less sensitive
and specific than chromatographic methods. Attempts to modify the nitric
acid oxidation method and the 4-amino antipyrine (4-amino-2,3-dimethyl-
l-phenyl-3-pyrazolin-5-one) colorimetric method to improve selectivity
and lower detection limits have not been very successful when only small
amounts of sample are available (Bevenue and Beckman, 1967). Infrared
or ultraviolet spectrophotometry can also be used to identify and deter-
mine pentachlorophenol. These methods must be preceded by purification
steps which effectively separate the pentachlorophenol from interfering
substances with similar absorptivity.
Chromatography has become very important as a method of separation
and as a means of assay. High-pressure liquid chromatography with
Amberlite XAD-7 resin (Fritz and Willis, 1973) has been used recently to
separate complex mixtures of phenols. Thin-layer chromatography and
paper chromatography can be used to separate pentachlorophenol from many
interfering substances (Bevenue and Beckman, 1967). Thin-layer chroma-
tography can also be used to estimate semiquantitatively the amount of
the compound present in microgram quantities (Zigler and Phillips, 1967;
Davies and Thuraisingham, 1968; Geike, 1972; and Frei-Hausler, Frei, and
Hutzinger, 1973).
The most widely used technique for analysis of pentachlorophenol in
practically all sample types is gas-liquid chromatography. The electron-
capture detector is used routinely because of its high sensitivity to
halogenated compounds; quantities in the nanogram to picogram range
(10~9 to 10~12 g) can be measured. The gas-liquid chromatography tech-
nique is often sufficient to analyze and identify pentachlorophenol if
retention times are determined on two or more columns.
When more rigorous identification is required and when a sufficient
amount of sample is available for the collection of a gas chromatographic
fraction of the suspected pentachlorophenol, final confirmation of identity
must be obtained by ultraviolet or infrared spectroscopy. With the advent
of computerized gas chromatography—mass spectrometer interfaces (Elkin et
al., 1973), it is possible to scan automatically the mass fragments ex-
pected from the pentachlorophenol molecule. This technique uses the mass
spectrometer as a molecule-specific detector. There are also less sophis-
ticated systems in which the mass spectrometer is used to take the spec-
trum of only a few selected peaks. This technique is still very useful
because the mass spectrum of a compound is normally an unambiguous
identifier.
Pentachlorophenol is most often isolated from samples by a series
of liquid-liquid extractions. The most common technique for soil samples
-------
256
is extraction with sodium or potassium hydroxide, followed by acidifica-
tion of the extract and extraction from the acid solution with a nonpolar
solvent such as benzene, toluene, or petroleum ether. The phenol is then
reextracted from the nonpolar solvent with a basic aqueous solution if
further purification is desired. Biological tissue samples have been
treated in much the same way, although sometimes the tissue is treated
with concentrated sulfuric acid (Erne, 1958) and anhydrous sodium sul-
fate and extracted by a Soxhlet technique. Recovery is variable (90Z to
95Z) but is similar to other methods. Steam distillation is used for
isolation of larger (milligram) amounts of pentachlorophenol in soil and
biological tissue. Water samples are easiest to handle. Host investi-
gators simply acidify a large amount of water and extract it directly
with a nonpolar organic solvent. Recoveries are greater (>95Z) and
detection limits lower (aicrogram/liter) for water samples than for
other environmental samples (Stark, 1969; Rudling, 1970; Chau and Coburn,
1974; Renberg, 1974).
Soae problems with isolation techniques have been reported. Diffi-
culties were encountered in removal of pentachlorophenol from samples
with a high fat content (Renberg, 1974), especially fat of marine origin,
and from certain soil samples which formed gels when their alkaline ex-
tract was acidified to a pH lower than 6 (Stark, 1969). Because penta-
chlorophenol has a pK value of 5, extraction under these circumstances
can be difficult or impossible. These difficulties can be eliminated by
ion-exchange reactions (Renberg, 1974). In this procedure, acidic
substances are bound to an anion exchanger and the liquid phase can be
discharged. This method gave recovery values of >97Z from soil «TUJ
water and of 92Z from fish.
In summary, the chemical methods for isolation and determination
of pentachlorophenol exploit the dual nature of the compound — it exists
as a polar anion under basic conditions and as a nonpolar molecule when
acidified. This property allows its partitioning to be controlled
easily.
-------
257
SECTIOH D.2
REFERENCES
1. Anonyaous. 1972. Chemical Profile: Pentachlorophenol. Chea. Mark.
Rep. 201:9.
2. Barthel, W. F., A. Curley, C. L. Thrasher, V. A. Sedlak, and R.
Armstrong. 1969. Determination of Pentachlorophenol in Blood,
Urine, Tissue, and Clothing. J. Assoc. Off. Anal. Chea. 52(2):294-298.
3. Bevenae, A., and H. Beckman. 1967. Pentachlorophenol: A Discussion
of Its Properties and Its Occurrence as a Residue in Huaan and Animal
Tissues. Residue Rev. 19:83-134.
4. Bevenue, A., M. L. Eaersbn, L. J. Casarett, and W. L. Yauger, Jr.
1968. A Sensitive Gas Chroaatographic Method for the Deteraination
of Pentachlorophenol in Huaan Blood. J. Chroaatogr. 38(4):467-472.
5. Bevenue, A., J. R. Wilson, E. F. Potter, M. K. Song, H. Beckaan,
and G. Hal Lett. 1966. A Method for the Determination of Penta-
chlorophenol in Huaan Urine in Picograa Quantities. Bull. Environ.
Contaa. Toxicol. 1(6):257-266.
6. Briggs, G. G. 1975. The Behaviour of the Hitrification Inhibitor
"H-Serve" in Broadcast and Incorporated Applications to Soil. J.
Sci. Food Agric. 26:1083-1092.
7. Buhler, D. R., M. E. Rasausson, and H. S. Nakaue. 1973. Occurrence
of Hexachlorophene and Pentachlorophenol in Sewage and Hater. Environ.
Sci. Technol. 7(10):929-934.
8. Casarett, L. J., A. Bevenue, W. L. Yauger, Jr., and S. A. Whalen.
1969. Observations on Pentachlorophenol in Huaan Blood and Urine.
Aa. Ind. Hyg. Assoc. J. 30(4):36O-366.
9. Chan, A.S.Y., and J. A. Coborn. 1974. Deteraination of Pentachloro-
phenol in Hatural and Waste Waters. J. Assoc. Off. Anal. Chea.
57(2):389-393.
10. Chesters, G., H. B. Pionke, and T. C. Daniel. 1974. Extraction and
Analytical Techniques for Pesticides in Soil, Sediaent, and Rater.
In: Pesticides in Soil and Water, W. D. Guenzi, ed. Soil Science
Society of Aaerica, Madison, Wis. pp. 451-550.
11. Choi, J., and S. Aoaine. 1972. Effects of the Soil on the Activity
of Pentachlorophenol. Soil Sci. Plant Hutr. (Tokyo) 18(6):255-260.
12. Choi, J., and S. Aoaine. 1974a. Adsorption of Pentachlorophenol by
Soils. Soil Sci. Plant Hutr. (Tokyo) 20(2):135-144.
-------
258
13. Choi, J., and S. Aomine. 19742?. Mechanisms of Pentachlorophenol
Adsorption by Soils. Soil Sci. Plant Nutr. (Tokyo) 20(4):371-379.
14. Comstock, E. G., B. S. Comstock, and K. Ellison. 1967. A Turbidi-
metric Method for the Determination of Pentachlorophenol in Urine.
Clin. Chem. (Winston-Salem, N.C.) 13(12):1050-1056.
15. Cranmer, M. , and J. Freal. 1970. Gas Chromatographic Analysis of
Pentachlorophenol in Human Urine by Formation of Alky! Ethers.
Life Sci. 9(3):121-128.
16. Davies, J. R., and S. T. Thuraisingham. 1968. The Detection and
Estimation of Pentachlorophenol in Natural Latex by Thin-Layer
Chromatography. J. Chromatogr. 35(l):43-46.
17. Deichmann, W., and L. J. Schafer. 1942. Spectrophotometric Estima-
tion of Pentachlorophenol in Tissues and Water. Ind. Eng. Chem. Anal.
Ed. 14(4):310-312.
18. Dobrovolny, C. G., and W. T. Raskins. 1953. Effects of Soils and
Sunlight on Dilute Concentrations of Sodium Pentachlorophenate.
Science 117:501-502.
19. Doedens, J. D. 1963. Chlorophenols. In: Kirk-Othmer Encyclopedia
of Chemical Technology, 2nd ed., Vol. 5. John Wiley and Sons,
Interscience Publishers, New York. pp. 325-338.
20. Elkin, K., L. Pierrou, U. G. Ahlborg, B. Holmstedt, and J. E. Lindgren.
1973. Computer-Controlled Mass Fragmentography with Digital Signal
Processing. J. Chromatogr. 81(1):47-55.
21. Erne, K. 1958. The Toxicological Detection and Determination of
Pentachlorophenol. Acta Pharmacol. Toxicol. 14:158-172.
22. Fountaine, J. E., P. B. Joshipura, P. N. Keliher, and J. D. Johnson.
1975. Determination of Pentachlorophenol by Ultraviolet Ratio
Spectrophotometry. Anal. Chem. 47(1):157-159.
23. Frei-HMusler, M., R. W. Frei, and 0. Hutzinger. 1973. An Investiga-
tion of Fluorigenic Labelling of Chlorophenols with Dansyl Chloride.
J. Chromatogr. 84(1):214-217.
24. Fritz, J. S., and R. B. Willis. 1973. Chromatographic Separation
of Phenols Using an Acrylic Resin. J. Chromatogr. 79:107-119.
25. Fuller, B., R. Holberger, D. Carstea, J. Cross, R. Berman, and P. Walker,
1977. The Analysis of Existing Wood Preserving Techniques and Possible
Alternatives. MITRE Technical Report 7520. Metrek Division, The MITRE
Corporation. 160 pp.
-------
259
26. Gee, M. G., D. G. Land, and D. Robinson. 1974. Simultaneous Analysis
of 2,3,4,6-Tetrachloroanisole, Pentachloroanisole and the Corresponding
Chlorophenols in Biological Tissue. J. Sci. Food Agric. 25(7):829-834.
27. Geike, F. 1972. Diinnschichtchromatographisch-Enzymatischer Nachweis
Einiger Lindan-und Theoretisch Mb'glicher DDT-Metaboliten Sowie von
Pentachlorophenol (Thin-Layer Chromatographic-Enzymatic Identifica-
tion of Some Lindane- and Possible DDT-Metabolites as Well as Penta-
chlorophenol) . J. Chromatogr. 67(2):343-349.
28. Raskins, W. T. 1951. Colorimetric Determination of Microgram
Quantities of Sodium and Copper Pentachlorophenates. Anal. Chem.
23(11):1672-1674.
29. Higginbotham, G. R., J. Ress, and A. Rocke. 1970. Extraction and
GLC Detection of Pentachlorophenol and 2,3,4,6-Tetrachlorophenol in
Fats, Oils, and Fatty Acids. J. Assoc. Off. Anal. Chem. 53(4):673-676.
30. Hilton, H. W., and Q. H. Yuen. 1963. Adsorption of Several Pre-
emergence Herbicides by Hawaiian Sugar Cane Soils. J. Agric. Food
Chem. 11(3):230-234.
31. Renberg, L. 1974. Ion Exchange Technique for the Determination of
Chlorinated Phenols and Phenoxy Acids in Organic Tissue, Soil, and
Water. Anal. Chem. 46(3):459-461.
32. Resch, H., and D. G. Arganbright. 1971. Location of Pentachloro-
phenol by Electron Microprobe and Other Techniques in Cellon Treated
Douglas-Fir. For. Prod. J. 21(1):38-43.
33. Rudling, L. 1970. Determination of Pentachlorophenol in Organic
Tissues and Water. Water Res. 4(8):533-537.
34. Shafik, T. M. 1973. The Determination of Pentachlorophenol and
Hexachlorophene in Human Adipose Tissue. Bull. Environ. Contam.
Toxicol. 10(l):57-63.
35. Stark, A. 1969. Analysis of Pentachlorophenol Residues in Soil,
Water, and Fish. J. Agric. Food Chem. 17(4):871-873.
36. van Langeveld, H.E.A.M. 1975. Determination of Pentachlorophenol
in Toy Paints. J. Assoc. Off. Anal. Chem. 58(1):19-22.
37. Williams, A. I. 1971. The Separation and Determination of Penta-
chlorophenol in Treated Softwoods and Preservative Solutions.
Analyst (London) 96(1141):263-305.
38. Zigler, M. G., and W. F. Phillips. 1967. Thin-Layer Chromatographic
Method for Estimation of Chlorophenols. Environ. Sci. Technol.
l(l):65-67.
39. Zitko, V., 0. Hutzinger, and P.M.K. Choi. 1974. Determination of
Pentachlorophenol and Chlorobiphenylols in Biological Samples.
Bull. Environ. Contam. Toxicol. 12(6):649-653.
-------
D.3 BIOLOGICAL ASPECTS IN MICROORGANISMS
D.3.1 BACTERIA
D.3.1.1 Metabolism
Bacterial metabolism and detoxification of pentachlorophenol occurs
in the environment and in the laboratory. Because pentachlorophenol deg-
radation and metabolism by microorganisms is an important facet of its
dissipation from the environment, this subject is discussed extensively
in Section D.7.3.5; only a brief overview is presented in this section.
Certain soil bacteria are able to detoxify pentachlorophenol by
methylation, which results in the formation of pentachloroanisole (Suzuki
and Nose, 1971, as cited in Cserjesi, 1972). Bacteria resistant to the
toxic effect of sodium pentachlorophenate have been isolated from pon-
derosa pine stakes treated with pentachlorophenol (Morton, Stewart, and
Bruneau, 1969). Bacteria isolated from treated and untreated stakes
were capable of growing on media containing 0.5% pentachlorophenol in
laboratory tests. The authors pointed out that the significance of this
pentachlorophenol-resistant bacterium to the ultimate fate of the preserv-
ative is not known. The bacteria (not identified) may play a role in
modification of pentachlorophenol, but this possibility has not been
examined.
Chu and Kirsch (1972, 1973) isolated a bacterial strain (designated
KC-3) from a continuous-flow enrichment culture shown to metabolize
pentachlorophenol as a sole source of organic carbon and energy. Penta-
chlorophenol was degraded readily by the organism with the release of
high levels of chloride, quantitative disappearance of the substrate,
and an almost quantitative oxygen uptake. The source of the initial
bacterial inoculation from which KC-3 was isolated was not described.
Kirsch and Etzel (1973) cultured an acclimated mixed bacterial popu-
lation capable of biodegrading sodium pentachlorophenate; biodegradation
was measured by release of ll4C during a 24-hr exposure. The initial
inoculum was isolated from soil obtained from the grounds of a wood prod-
ucts manufacturer who used pentachlorophenol as a preservative. The
initial sample was obtained from an area where the soil was well saturated
with pentachlorophenol. The culture was gradually acclimated to increas-
ing levels of pentachlorophenol until, after three months, pentachloro-
phenol was added to the cultures at a level of 120 mg/day. At this point
the mixed culture (both proliferating and nonproliferating) was capable
of pentachlorophenol biodegradation, but no attempt was made to char-
acterize the species.
Watanabe (1973) isolated a bacterial culture capable of growing on
and degrading pentachlorophenol in a medium containing organic salts and
40 mg/liter pentachlorophenol as a sole source of carbon. He determined
from morphological and physiological properties that the bacteria was of
the genus Pseudomonas or a closely related genus. The pathways of penta-
chlorophenol metabolism in bacteria have not been elucidated.
260
-------
261
D.3.1.2 Effects
Pentachlorophenol and sodium pentachlorophenate are toxic or inhibi-
tory to most forms of bacteria. In fact, pentachlorophenol is a well-
known, widely used antimicrobial substance. Most industrial uses of
pentachlorophenol depend on its ability to serve as a wood preservative
by controlling bacteria and fungi. Detailed information on the mech-
anisms of pentachlorophenol toxicity to bacteria is scanty; however, the
uncoupling of oxidative phosphorylation is generally believed to be of
major importance. Many bacteria which are susceptible to control by
pentachlorophenol depend primarily on anaerobic fermentation for their
energy source. Thus, a mechanism for pentachlorophenol toxicity must
include an explanation for the sensitivity of anaerobes to this compound.
The antimicrobial efficiency of pentachlorophenol for various species of
bacteria and fungi is presented in Table D.3.1. Growth responses of three
other species of bacteria are shown in Table D.3.2.
TABLE D.3.1. ANTIMICROBIAL EFFICIENCIES OF
PENTACHLOROPHENOLa
Concentration of
_ . pentachlorophenol
Test organism K. .,.,,.
for inhibition
(ing/liter)
Tirichodevma wiride 25-50
Trichoderma sp. 10-25
Ceratocystis pilifera 5-10
Polypovus tul-ipiferae <1
Rhisopus stolanifer 1
Lenzites trabea 1-2.5
Ceratoeystis ips 10-25
Chaetomium gldboswn 1-2.5
Aspergillus niger 10-25
Bacillus eereus var. mycoi-des 5-10
Bacillus subtilis 50-100
Escherichia col-i 250-500
Pseudomonas aevuginosa 1000-2500
Enterdbacter aevogenes 500-1000
Streptomyces gviseus 5-10
Flavobacteriion arborescens 2.5-5
Dow Chemical Company purified grade, propri-
etary name Dowicide EC-7.
Source: Adapted from Dow Chemical Company,
undated, p. 2. Reprinted by permission of the
publisher.
-------
262
TABLE D.3.2. GROWTH INHIBITION OF BACTERIA BY
PENTACHLOROPHENOL
Minimal response
concentration of Inhibition
pentachlorophenol (%)
(yg/ml)
Ewin-La cavotovova 10 29.6
Pseudomonas fluorescens 25 65.8
Bacillus sp. 5 100
^Significant at the 5% level.
Significant at the 1% level.
Source: Adapted from Breazeale and Camper, 1972,
Table 1, p. 432. Reprinted by permission of the publisher.
Mickelson (1974) studied the inhibitory effect of pentachlorophenol
on the growth of Streptococcus agalacti-ae. Aerobic molar growth yields
(growth per mole of substrate) of the bacterium were depressed in the
presence of pentachlorophenol to values equal to or less than those sup-
ported by substrate-level phosphorylation. The uncoupling action of
pentachlorophenol was assumed to be responsible for this inhibitory effect.
When the only source of energy available to the organism was from substrate-
level phosphorylation (under conditions where anaerobic growth occurred), a
severe depression of the molar growth yield was noted in the presence of
pentachlorophenol. These results indicate that pentachlorophenol was also
affecting the generation of ATP by substrate-level phosphorylation, but
the mechanism of this process is not understood. Thus, in bacterial systems
pentachlorophenol apparently affects not only oxidative phosphorylation,
but also generation of ATP at the level of glycolysis or effective utiliza-
tion of the ATP generated at this level. Inhibition of glycolytic enzymes,
which has been demonstrated in higher animals, may be responsible for the
effects noted in bacteria.
Heidman, Kincannon, and Gaudy (1967) studied the metabolic responses
of activated sludge to the addition of sodium pentachlorophenate. Pro-
longed exposure resulted in significant changes in the predominant species
of bacteria in the activated sludge, but the specific nature of these
changes was not examined. Under conditions of shock loading, fairly
small doses of sodium pentachlorophenate impaired the efficiency of the
system. Successively more deleterious effects were seen in response to
5, 15, and 30 mg/liter sodium pentachlorophenate. Because concentra-
tions required to inhibit bacterial cell growth vary from 1 to 2500 ppm
pentachlorophenol for different species, it was not possible to determine
whether the inhibition was due to an overall effect on all bacterial
-------
263
species or to an increasingly severe selection of species under shock-
loading conditions. This interference with the degradative activities of
sludge bacteria has important ramifications for biological treatment sys-
tems. Heidman, Kincannon, and Gaudy (1967) found that with sufficient
acclimation an activated sludge system can operate in the presence of
sodium pentachlorophenate concentrations as high as 250 mg/liter without
serious retardation of biochemical purification efficiency. Apparently,
the most serious threat to efficient activated sludge treatment of sewage
by pentachlorophenol is under shock-loading conditions. The question of
how pentachlorophenol affects the normal biological breakdown of glucose
was also addressed in this study. No attempt was made to assess the
degree of biological breakdown of pentachlorophenol in the activated sludge
treatment. Sodium pentachlorophenate was not used as a substrate by the
bacteria and did not exhibit any detectable biochemical oxygen demand.
D.3.2 FUNGI
D.3.2.1 Metabolism
Some species of fungi which tolerate the presence of pentachlorophenol
are able to grow and reproduce in its presence, but they do not possess the
ability to degrade the preservative. Other species of resistant fungi are
able to degrade pentachlorophenol in treated wood and in soil block tests.
For example, Cserjesi (1967) demonstrated that an isolate of Cephatoascus
fvagfans was tolerant to concentrations of pentachlorophenol found in
treated wood, but it did not have the capacity to degrade the preservative.
On the other hand, three Triohoderma spp. were capable of tolerating the
compound and degrading it in malt extract solutions. This degradation
took place during a 12-day incubation period. Unligil (1968) isolated 27
strains of fungi — some from wood treated with fungicides — and determined
the tolerance of pentachlorophenol on malt agar. The most tolerant fungi
were Tirichoderma viri,de3 Glioclad-iwn viride, and Cephaloasous fragrans
(Table D.3.3). Species more sensitive than these three included Alternaria
db-ietiSj A. tenuis3 Chaetorrrium globoswn, C. -LndLoion3 Coniophora puteana3
Daldinia concentfica, Graph-Lion penic-ill-icrides, Hormodendpum elajdosporio-ides3
Hypoxylon sp., Lenzites saepiariaj Libertella sp., Phoma sp., Polyst-ictus
versicolorj Pullularia pullulansj Stereum hivsutum, Trametes variiformis3
and Trog-La crispa. Within 52 days, T. wLride and C. puteana depleted
approximately 62% of the pentachlorophenol from samples with an initial
content of 5.8 kg/m3. Duncan and Deverall (1964) also demonstrated the
ability of several common wood-inhabiting fungi to deplete pentachloro-
phenol in treated wood blocks. These species did not produce wood decay
following degradation of the preservative.
The mechanism of pentachlorophenol detoxification by fungi is not
well understood. Methylation of the compound has been suggested as a
primary step in detoxification. Fungi have been shown to produce penta-
chloroanisole from pentachlorophenol during degradative processes (Curtis
et al., 1974). This methylation reaction is thought to occur in boiler
house litter, causing musty taint in chickens. It also seems likely that
musty taint in water supplies may result from a similar process. A
possible detoxification scheme for pentachlorophenol has been outlined
-------
264
TABLE D.3.3. LENGTH OF LAG PHASE AND RATE OF GROWTH OF TRICHODERMA VIRIDE, GLIOCLADWM VIRIDE,
AND CEPHALOASCUS FRAGRANS IN MALT AGAR CONTAINING SODIUM PENTACHLOROPHENATE
Concentration
of sodium
pentachlorophenate
(moles/liter)
0
1 x 10-"
2 x ID'*
4 x 10""
8 x 10'*
T.
Lag phase
(days)
0.6
1.2
2.2
3.0
5.4
wiride
Growth rate
(mm/ day)
35.7
3.04
1.65
0.87
0.48
G.
Lag phase
(days)
0.6
1.2
2.0
2.6
No growth
viin.de
Growth rate
(mm/day)
17.9
1.85
0.94
0.52
C.
Lag phase
(days)
0.6
1.2
2.0
2.4
No growth
fragrans
Growth rate
(mm/ day)
1.7
0.60
0.31
0.19
Source: Adapted from Unligil, 1968, Table 2, p. 48. Reprinted by permission of the publisher.
by Stranks (1976) (Figure D.3.1). According to this scheme, pentachloro-
phenol is oxidized to quinoids, chloranil, and tetrachlorobenzoquinone-
(1,2). These compounds then combine with pentachlorophenol to yield
trichloro-(pentachlorophenoxy)-benzoquinone-(1,4) or dichloro-bis(penta-
chlorophenoxy)-benzoquinone-(l,2).
D.3.2.2 Effects
Most data on the toxicity of pentachlorophenol to fungi deal with
common wood-destroying fungi (Table D.3.4). Interest in the antifungal
activity of pentachlorophenol stems from attempts to determine the most
efficient use of the preservative for control of fungi in treated wood.
Table D.3.5 lists the toxic effects of pentachlorophenol on a variety of
commonly found fungi. The effect of pentachlorophenol on spore germina-
tion, growth, and sporulation of three fungal plant pathogens is shown
in Table D.3.6. The minimum effective concentration of pentachlorophenol
for inhibition of radial growth of Trichoderma viride was 1.2 x 10"6
moles/liter (Blackman, Parke, and Carton, 1955).
D.3.3 ALGAE
D.3.3.1 Metabolism
No information was found on the metabolism of pentachlorophenol by
algae.
D.3.3.2 Effects
Pentachlorophenol is extremely toxic to algae. Huang and Gloyna
(1967) reported that pentachlorophenol was the most toxic compound among
ten halogenated phenols tested on Chlorella pyrenoidosa. The lethal
dosage of pentachlorophenol was 7.5 yg/liter. Even at a concentration
as low as 1.5 ug/liter, pentachlorophenol inhibited chlorophyll synthesis
for two days.
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265
ORNL-DWG 78-10509
Cl Cl
2 PENTACHLOROPHENOL
Figure D.3.1. Probable detoxification of pentachlorophenol by the
laccase of Coiriolus versi-color. Source: Adapted from Stranks, 1976,
Figure 2, p. 14. Reproduced by permission of the Minister of Supply and
Services Canada.
Pentachlorophenol and sodium pentachlorophenate were effectively
used as algicides for the control of stoneworts of the genera Chara and
Nitella in paddy fields in West Bengal (Table D.3.7) (Mukherji, 1972).
At doses as low as 3.75 kg/ha, small snails and fish were killed by the
compounds. Some minor damage to the rice crop occurred as small spots
which appeared on the young leaves, but no adverse effects on crop growth
were noted. A 2.0 rag/liter solution of sodium pentachlorophenate and
sodium salts of other phenols in the culture medium inhibited 50% of the
test algae in a 21-day laboratory incubation test (Palmer and Maloney,
1955). The growth of algae in filtered water from a spray pond used for
storing cooling water was prevented by 15 mg/liter sodium pentachloro-
phenate; in pond water containing algae, growth was stopped in seven
days (Gelfland, 1941). Algae stopped growing immediately in water con-
taining a concentration of 20 mg/liter sodium pentachlorophenate.
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266
TABLE D.3.4. THRESHOLD VALUES FOR
PENTACHLOROPHENOL TOXICITY TO
WOOD-DESTROYING FUNGI
Test fungus
Threshold
pentachlorophenol
I.
II.
III.
Fames subroseus
Polystictus tulip ferae
Poria incrassata
Poria montieola B
Polyst-ictus adustus
Poria montieola A
Polystictus versicolor
Polystictus hirsutus
Lenzites tvdbea A
Lenti,nus lep-ideus
Polyst-ictus db-ietinus
Porta vaillantii
Poria xantha
Lenzites tr>dbea B
Daedalea quercina
Lenzites saep-iapia
Schizophyllitm commune
Sterewn frustuloswn
(kg/m3)
3.85
1.77
1.2
0.98
0.98
0.85
0.77
0.69
0.63
0.48
0.48
0.48
0.40
0.35
0.35
0.18
0.18
0.18
(lb/ft3)
0.24
0.11
0.075
0.061
0.061
0.053
0.048
0.043
0.039
0.030
0.030
0.030
0.025
0.022
0.022
0.011
0.011
0.011
Source: Adapted from Sproule, 1960, p.
Reprinted by permission of the publisher.
46.
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267
TABLE D.3.5. TOXICITY OF PENTACHLOROPHENOL AND SODIUM PENTACHLOROPHENATE TO FUNGI
Amount
causing
total inhibition
Amount
causing death
(mg/liter)
Fungus
Ceratostomella pilifera
Hormonema dematioides
Hormodenarum aladosporioides
Polystiatus versiaolor
Polystiatus hirsutus
Coniophora oerebella
Fames roseus
F.P.L. No. 517a
Lentinus lepideus
Poria inarassata
Trametes serialis
Lenzites saepiaria
Lenzites trabea
Meruli'us domesticus
U-10
Triahophyton rosaaeum
Triahophyton interdigitale
Epidermophyton inguinale
Aspergillus niger
Peniaillium ahrysoginten
Penicillium dtgitatwn
•Alternaria radiaina
Rhizopus nigriaans
Fusariwn vasinfeatum
Penta-
chlorophenol
60
60
60
80
80
20
60
20
20
20
10
20
20
<10
20
AO
60
AO
60
60
AO
60
AO
100
Sodium
penta-
chlorophenate
60
60
500
100
200
20
60
30
20
20
20
20
20
<10
20
AO
60
AO
60
60
AO
60
80
100
Penta-
(mg/liter)
Sodium
chlorophenol , , ,
chlorophenate
60
60
500
100
200
20
60
60
AO
20
20
60
AO
<10
20
60
80
AO
80
AO
60
60
200
80
80
300
100
100
20
60
60
AO
20
20
AO
AO
<10
20
AO
80
60
60
60
60
80
200
Formerly known as Fames annosus.
Source: Adapted from Carswell and Nason, 1938, Table II, p. 625. Reprinted by permis-
sion of the publisher.
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TABLE D.3.6. EFFECTS OF PENTACHLOROPHENOL (0.01 mole/liter) ON SPORE GERMINATION, GROWTH, AND SPORULATION
OF HELMINTHOSPORIUM ORYZAE, ALTERNARIA SOLANI, AND CURVULARIA LUNATA
Compound
Pentachlorophenol
Control
Low pH control
(malic acid)
H. oryzae
Ger-
mination Growth
(%)
0 1
80 3
80 3
Sporur
lation
0
3
3
A. solani
Ger-
mination Growth
(%)
0 1
85 3
84 3
SporiiT-
lation^
1
3
3
Ger-
mination
(%)
0
50
50
C. lunata
Growth
1
3
3
Sporur
lation6
0
3
3
NJ
ON
00
a
,0, 1, 2, and 3 indicate nil, low, moderate, and high growth.
0, 1, 2, and 3 indicate nil, low, moderate, and high sporulation.
Source: Adapted from Mukherjee and Kundu, 1973, Table 1, p. 90. Reprinted by permission- of the publisher.
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269
TABLE D.3.7. CONTROL OF CHARA AND NITELLA SPECIES WITH CHEMICALS
APPLIED 60 DAYS AFTER TRANSPLANTING THE PADDY
Location of
application
Ramchandrapur ,
West Bengal,
1970
Siddheswarpur ,
West Bengal,
1971
Janerdanpur ,
West Bengal,
1971
Days
after
application
15
7
16
7
16
Pentachlorophenol
Dose
(kg/ha)
5.0
3.75
3.75
4.4
4.4
Algae
killed
(%)
90
90
95
90
100
Sodium
pentachlorophenate
Dose
(kg/ha)
5.0
2.5
2.5
3.75
3.75
Algae
killed
(%)
95
75
90
100
100
Source: Adapted from Mukherji, 1972, Table 1, p. 390. Reprinted by
permission of the publisher.
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270
SECTION D.3
REFERENCES
1. Blackman, G. E., M. H. Parke, and G. Carton. 1955. The Physio-
logical Activity of Substituted Phenols: I. Relationships between
Chemical Structure and Physiological Activity. Arch. Biochem. Biophys.
54:45-54.
2. Breazeale, F. W., and N. D. Camper. 1972. Effect of Selected Herbi-
cides on Bacterial Growth Rates. Appl. Microbiol. 23(2):431-432.
3. Carswell, T. S., and H. K. Nason. 1938. Properties and Uses of
Pentachlorophenol. Ind. Eng. Chem. 30(6):622-626.
4. Chu, J. P., and E. J. Kirsch. 1972. Metabolism of Pentachloro-
phenol by an Axenic Bacterial Culture. Appl. Microbiol. 23(5):
1033-1035.
5. Chu, J., and E. J. Kirsch. 1973. Utilization of Halophenols by a
Pentachlorophenol Metabolizing Bacterium. Dev. Ind. Microbiol.
14:264-273.
6. Cserjesi, A. J. 1967. The Adaptation of Fungi to Pentachlorophenol
and Its Biodegradation. Can. J. Microbiol. 13(9):1243-1249.
7. Cserjesi, A. J. 1972. Detoxification of Chlorinated Phenols. Int.
Biodetior. Bull. 8(4):135-138.
8. Curtis, R. F., C. Dennis, J. M. Gee, M. G. Gee, N. M. Griffiths,
D. G. Land, J. L. Peel, and D. Robinson. 1974. Chloroanisoles as
a Cause of Musty Taint in Chickens and Their Microbiological Forma-
tion from Chlorophenols in Broiler House Litters. J. Sci. Food
Agric. 25:811-828.
9. Dow Chemical Company. Undated. Dowicide EC-7 Antimicrobial.
Midland, Mich. 3 pp.
10. Duncan, C. G., and F. J. Deverall. 1964. Degradation of Wood Pre-
servatives by Fungi. Appl. Microbiol. 12(1):57-62.
11. Gelfland, M. 1941. Sodium Pentachlorophenate Treatment for Cooling
Water (abstract). Water Pollut. Abstr. 14:173.
12. Heidman, J. A., D. F. Kincannon, and A. F. Gaudy, Jr. 1967. Metabolic
Response of Activated Sludge to Sodium Pentachlorophenol. Proc. Ind.
Waste Conf. 22:661-674.
13. Huang, J. C., and E. F. Gloyna. 1967. Effects of Toxic Organics on
Photosynthetic Reoxygenation. University of Texas, Center for Research
in Water Resources, Austin. 163 pp.
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271
14. Kirsch, E. J. , and J. E. Etzel. 1973. Microbial Decomposition of
Pentachlorophenol. J. Water Pollut. Control Fed. 45(2):359-364.
15. Mickelson, M. N. 1974. Effect of Uncoupling Agents and Respiratory
Inhibitors on the Growth of Streptococcus agalact-iae. J. Bacteriol.
120(2):733-740.
16. Morton, H. L. , J. L. Stewart, and G. P. Bruneau. 1969. Isolation of
Microorganisms from Preservative-Treated Wood. For. Prod. J. 19(1):
38-41.
17. Mukherjee, N. , and B. Kundu. 1973. Antifungal Activities of Some
Phenolics and Related Compounds to Three Fungal Plant Pathogens.
Phytopathol. Z. 78(l):89-92.
18. Mukherji, S. K. 1972. Use of Pentachlorophenol as an Algicide in
Paddy Fields in West Bengal. Weed Res. 12(4):398-390.
19. Palmer, C. M. , and T. E. Maloney. 1955. Preliminary Screening for
Potential Algicides. Ohio J. Sci. 55(1):l-8.
20. Sproule, J. 1960. Pentachlorophenol: Its Properties as a Wood
Preservative. Pest. Technol. 2:41-47.
21. Stranks, D. W. 1976. Wood Preservatives: Their Depletion as
Fungicides and Fate in the Environment. Department of the Environ-
ment, Canadian Forestry Service, Ottawa, Canada. 35 pp.
22. Unligil, H. H. 1968. Depletion of Pentachlorophenol by Fungi.
For. Prod. J. 18(2):45-50.
23. Watanabe, I. 1973. Isolation of Pentachlorophenol Decomposing
Bacteria from Soil. Soil Sci., Plant Nutr. (Tokyo) 19(2) :109-116.
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D.4 BIOLOGICAL ASPECTS IN PLANTS
D.4.1 METABOLISM
Very little information is available on the distribution and transport
of pentachlorophenol in vascular plants. Hilton, Yuen, and Nomura (1970)
studied the distribution of pentachlorophenol residues in sugar cane follow-
ing either foliar or root application. Both sides of the three top leaves
were painted with [14C]pentachlorophenol in an amount equivalent to 6 mg of
sodium pentachlorophenate per plant in aqueous solution containing 10%
methanol. Samples taken at two, four, and eight weeks included treated
leaves, untreated green leaves, dry leaf trash, stalks, roots, and suckers.
These samples were analyzed for 1AC and, in some cases, the identity of the
labeled components was verified by electron-capture gas chromatography.
Between the first and last sampling period about 16% of the 14C[penta-
chlorophenol] was lost from the plants. This radioactivity did not appear
in any of the plant samples or in the nutrient solution in which the plants
were grown; thus, it was presumed to be lost from the treated leaves by
vaporization or weathering. Table D.4.1 shows that the radioactivity which
remained was confined primarily to the treated leaves. Small amounts of
pentachlorophenol were apparently distributed to all parts of the plant
except the roots. The authors suggested that the residual radioactivity
found in other portions of the plant may have resulted from translocation
of the vapor or from mechanical transfer of pentachlorophenol to untreated
portions of the plant. At eight weeks the leaves treated with pentachloro-
phenol were the lowest green leaves on the plants. Following abscission of
the leaves (about one leaf per ten days), the radioactivity was lost from
TABLE D.4.1. DISTRIBUTION OF [ ^C] PENTACHLOROPHENOL
IN SUGAR CANE AFTER FOLIAR APPLICATION
Distribution of recoverable radioactivity (%)
2 weeks after 4 weeks after 8 weeks after
application application application
Treated leaves
Untreated green leaves
Untreated, dry leaf trash
Stalk
Roots
Suckers
100
0
' 0
0
0
0
82
11
2.7
4.6
0
0
84
6.6
2.0
7.1
0
0.7
Source: Adapted from Hilton, Yuen, and Nomura, Table I, p. 218.
Reprinted by permission of the publisher.
272
-------
273
the plant. The amount of pentachlorophenol applied to these plants was
large enough to cause toxic symptoms such as moderate root and leaf injury.
Hilton, Yuen, and Nomura (1970) also investigated pentachlorophenol
distribution after root application. Sugar cane plants were grown in
covered crocks containing 3 liters of aerated nutrient solution with an
initial pentachlorophenol level of 5 mg/liter. The plants remained in the
radioactive solution for four weeks and then were removed; the roots were
washed, and the plants were placed in fresh nutrient solution free of
pentachlorophenol. Parts of the plant were removed at zero, four, and
eight weeks following transfer, and the samples were prepared and analyzed
in a manner similar to the methods used for samples from plants subjected
to foliar treatment. During the four-week treatment period, the radio-
activity of the nutrient solution decreased 86%. Aerated solutions with-
out plants showed extensive volatilization of pentachlorophenol. However,
considerable amounts of pentachlorophenol were taken up by the roots;
radioactivity decreased rapidly and exponentially in the nutrient solutions.
Of the 15 mg of pentachlorophenol applied, roughly 13.5 mg was recovered
from the plants at the end of the four-week exposure. During the eight-
week period when plants were growing in fresh nutrient solutions, the
pentachlorophenol content of the plants decreased by about 60%. More than
99% of the radioactivity absorbed and retained was found in the root system;
some remaining activity appeared in the stalk and suckers (Table D.4.2).
Pentachlorophenol was apparently retained in the root system throughout the
TABLE D.4.2. DISTRIBUTION OF
[^C] PENTACHLOROPHENOL IN SUGAR CANE
GROWN FOR FOUR WEEKS IN PENTACHLOROPHENOL-
TREATED NUTRIENT SOLUTION AND TRANSFERRED
TO PENTACHLOROPHENOL-FREE SOLUTION
Distribution of
recoverable radioactivity
r xdiiL pat L
Dry leaf trash
Green leaves
Stalk
Roots
Suckers
0 weeks
0
0
0.8
99
4 weeks
after
transfer
0
0
3.1
97
8 weeks
after
transfer
0
0
4.6
94
1.6
Source: Adapted from Hilton, Yuen, and
Nomura, 1970, Table II, p. 219. Reprinted by
permission of the publisher.
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274
entire experiment. Losses of pentachlorophenol from the root system
occurred without a concomitant increase in the pentachlorophenol content
of other plant parts or of the nutrient solution. The authors suggested
that the gradual release of radioactivity from the root system was followed
by volatilization of pentachlorophenol from the nutrient solution. Electron-
capture gas chromatography of root extracts indicated that <10% of the resi-
due had a retention time identical to that of pentachlorophenol. Hilton,
Yuen, and Nomura (1970) stated that "the remainder of the chromatographed
extract exhibited two small peaks with longer retention time than any of the
known chlorinated phenols." The substances, presumed to be metabolic break-
down products of pentachlorophenol, were not identified. At the same time
these investigators also studied the translocation and distribution of atra-
zine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and ametryne (2-
ethylamino-4-isopropylamino-6-methylthio-s-triazine) and provided substantial
evidence that these pesticides are translocated readily from roots to leaves.
Under identical test conditions, pentachlorophenol apparently does not trans-
locate readily but remains at the site of treatment until the substance is
metabolized or released from the plant tissue.
Conversely, Miller and Aboul-Ela (1969) found evidence of pentachloro-
phenol translocation in cotton plants (Deltapine variety) grown to maturity
in a greenhouse. Plants sprayed with [14C]pentachlorophenol accumulated
up to 2 yg/g pentachlorophenol (or its metabolites) in the cotton seed
kernels of bolls which were closed at the time of spraying; no pentachloro-
phenol was detected, however, in kernels from open bolls. Thus, penta-
chlorophenol was translocated from the external area of the bolls to the
kernels. The distribution of pentachlorophenol applied in single droplets
of diesel oil to young cotton seedlings was also determined. In separate
experiments, pentachlorophenol was applied either to the point of veinal
anastomosis of the first true leaf or at the juncture of the cotyledon and
its petiole. Application to the first true leaf resulted in some absorp-
tion and translocation through the veins of the leaf within 1 hr. Penta-
chlorophenol was evenly distributed through the veins of the treated leaf
after 8 hr, but no movement out of the treated leaf was observed after
eight days. When pentachlorophenol was applied to the cotyledon, the com-
pound was distributed uniformly through the veins of the cotyledonary petiole
within 4 hr. One day after pentachlorophenol application, all parts of the
seedling except the other cotyledon and the roots contained detectable levels
of pentachlorophenol. Apparently, radioactivity tends to concentrate in the
glandular hairs. Regrowth leaves from defoliated mature cotton plants con-
tained an average of 1.03 yg/g pentachlorophenol.
D.4.2 EFFECTS
D.4.2.1 Physiological or Biochemical Role
No evidence suggests that pentachlorophenol plays any normal role in
the physiology of plants; thus, no nutritional requirement exists.
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275
D.4.2.2 Toxicity
D.4.2.2.1 Mechanism of Action — Weinbach (1957) demonstrated that
pentachlorophenol can uncouple oxidative phosphorylation in isolated
animal mitochondria. Similarly, experiments by Uesugi and Fukunaga (1967,
as cited by Takahashi, 1971) with the mycelia of Piriev.laria oryzae, a
pathogen of rice blast, and by Matsunaka (1965, as cited by Takahashi,
1971) with cauliflower mitochondria showed that 10"6 mole of pentachloro-
phenol per liter produced an uncoupling action in plants. These studies
indicate that the uncoupling of oxidative phosphorylation is likely the
primary mechanism of pentachlorophenol phytotoxicity. The mechanisms of
the action of pentachlorophenol on plants have not been described in
detail; further investigations are warranted.
Takahashi (1971) studied the mechanism of suppression of germination
by pentachlorophenol based on phytate decomposition in germinating rice
seeds. Phosphorus appears in seeds primarily in organic form, and as much
as 80% of the total phosphorus may be in the form of phytic acid. The
level of inorganic phosphate may be the limiting factor in phosphate-
requiring metabolic reactions in the germinating seed. The large amount
of phytate present in seeds may serve as a source of inorganic phosphate.
Thus, liberation of phosphorus by decomposition of phytate may be essential
for germination to take place. By pretreating rice seeds with pentachloro-
phenol, Takahashi (1971) found that pentachlorophenol caused continuous
decomposition of "ester-phosphorus" in the germinating seedlings. The
author proposed that this effect of pentachlorophenol together with its
effect of uncoupling oxidative phosphorylation could be responsible for
the suppression of germination caused by insufficient usable energy. The
insufficient energy supply results in inadequate synthesis of phytase,
thereby short-circuiting the normal release of inorganic phosphate from
phytic acid. This proposed metabolic scheme and the points of action of
pentachlorophenol in the energy pathway of the developing seed are shown
in Figure D.4.1.
D.4.2.2.2 General Toxicity
D.4.2.2.2.1 Terrestrial plants — Pentachlorophenol is generally
toxic to vascular plants. Pentachlorophenol-treated flats used to grow
seedlings were tested for possible injurious effects on transplanted
tomato plants (Kaufert and Loerch, 1955). The flats were treated with 5%
pentachlorophenol either in Stoddard solvent or in No. 2 fuel oil and were
allowed to stand in a heated room for one month to eliminate most of the
solvent. The tomato plants were severely damaged in both instances. Fur-
thermore, plants started in these flats in subsequent years were also
damaged (Table D.4.3).
The effect of using pentachlorophenol-treated wooden trays to rear
coniferous seedlings for reforestation was studied by Ferguson (1959).
The containers were treated with 5% pentachlorophenol in diesel oil in a
4-hr cold-soak process, after which they were allowed to weather for 30
days prior to the planting of seedlings. All species tested were severely
damaged except longleaf pine (Pinus palustris Mill.). Symptoms included
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276
ORNL-DWG 78-10510
PHYTIC ACID
PHYTASE
PHYTASE FORMATION
PENTACHLOROPHENOL
PROTEIN
NUCLEIC
SYNTHESIS
ACIDS
ENERGY
SUPPLY
OXI DATIVE
PHOSPHORYLATION
ACID-INSOLUBLE FRACTION
NUCLEIC PHOSPHORUS
PROTEIN PHOSPHORUS
LIPID PHOSPHORUS
ESTER PHOSPHORUS
[IVTP
SUGAR PHOSPHORUS
PENTACHLOROPHENOL
= == = = = = > SITE OF ACTION OF PENTACHLOROPHENOL
Figure D.4.1. Schematic illustration of the inhibition of phytate
decomposition by pentachlorophenol in germinating rice seeds. Source:
Adapted from Takahashi, 1971, Figure 13, p. 23. Reprinted by permission
of the publisher.
TABLE D.4.3. EFFECT OF PENTACHLOROPHENOL PRESERVATIVE TREATMENT OF
WOODEN FLATS ON THE GROWTH OF TOMATO PLANTS
Treatment
5% pentachlorophenol
in Stoddard solvent
5% pentachlorophenol
in No. 2 fuel oil
Untreated sap pine
Cypress heartwood
Extent
KB t en L ion
(kg/m3) 1st
year
11 Severe
8 Severe
None
None
of injury to
2nd
year
Light
Moderate
None
None
tomato
3rd
year
None
Light
None
None
plants
4th
year
None
None
None
None
Source: Adapted from Kaufert and Loerch, 1955, p. 2. Reprinted by
permission of the publisher.
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277
needle twisting, followed by blanching and desiccation (Table D.4.4).
Plants grown in untreated flats which were adjacent to and west of
pentachlorophenol-treated flats were also damaged. The greenhouse was
cooled by exhaust fans in the east wall, and the prevailing air movement
was from east to west; therefore, it was suggested that damage was caused
by volatile compounds transported in air. This premise was further supported
by experiments in which soil from the pentachlorophenol-treated flats was
interchanged with soil from untreated flats. Mortality and damage occurred
only in the flats originally treated with pentachlorophenol. For the second
crop, although the damage seen in these flats was less than 50% of that in
the first crop, the persistence of pentachlorophenol was still substantial.
Table D.4.4 shows that different coniferous species vary considerably in
their reactions to pentachlorophenol. Slash pine (Pinus caribaea Morel.),
loblolly pine (P. taeda L.), and shortleaf pine (P. eohinata Mill.) suffered
extensive mortality, but longleaf pine (P. palustris Mill.) suffered no
mortality, although it displayed some symptoms of injury.
TABLE D.4.4. DEATH OR INJURY TO CONIFER SEEDLINGS GROWN
IN PENTACHLOROPHENOL-TREATED WOODEN TRAYS
5%
Diesel oil pentachlorophenol
oil
Pine species ....... , T . ,
r Killed Injured
Killed Injured
Pinus caribaea
Pinus taeda
Pinus echinata
Pinus pains tris
0
0
0
0
4
6
9
0
86
94
90
0
8
5
9
50
Source: Adapted from Ferguson, 1959, p. 22.
Carlson and Nairn (1974-1975) tested the effect of pentachlorophenol-
treated wood on containerized red pine (P. resinosa Ait.) and jack pine
(P. bariksiana Lamb.) seedlings. Severe injuries developed in both species.
Symptoms occurred within two days after initial exposure to pentachlorophenol
fumes. The flats used were treated with a 5% pentachlorophenol preservative
and then dried in a fume hood for three weeks prior to use. Seedlings
exposed to pentachlorophenol developed more slowly and exhibited necrosis
and twisted needles. Twisting of the needles became more pronounced, and
eventually the seedlings dropped over at the base and died. The sequence
of events was very similar for both species; however, red pine was slightly
more resistant (Table D.4.5).
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278
TABLE D.4.5. DEATH OR INJURY TO RED AND JACK PINE
SEEDLINGS GROWN IN PENTACHLOROPHENOL-TREATED FLATSa
, Penta-
No treatment chlorophenol
_. . treatment^
Pxne species
Killed Curled
Killed Curled
Pinus banksiana
Pinus resinosa
0 a
0 d
4.0 b
1.3 &
84 a
78 /
1.5 b
2.4 e
Number of seedlings observed ranged from 517 to
702.
The small letters indicate Duncan's multiple
range grouping of treatments which do not differ sig-
nificantly at the 5% level.
Source: Adapted from Carlson and Nairn, 1974-1975,
Tables 1 and 2, p. 34.
Ferree (1974) reported moderate to severe damage in high-density apple
orchards where posts freshly treated with pentachlorophenol were used as
supports for tree growth. Posts were set two to four weeks prior to plant-
ing of the trees. Within several months, leaf chlorosis was evident in all
trees planted closest to the posts. Golden Delicious trees (Malus domestica)
appeared to be the most susceptible to pentachlorophenol poisoning. Damage
included bark lesions, chlorosis, and, in severe cases, death of the branch
back to the graft union. Four trees died, and stunting and growth reduction
were evident among those less severely affected. Ferree (1974) suggested
hat if pentachlorophenol-treated posts are used, they should be weathered
by outside exposure for one year.
In the past, pentachlorophenol formulations have been used extensively
as herbicides in the United States and abroad. Although its use has declined
in the United States, its use elsewhere has continued. Pentachlorophenol is
used primarily as either a preemergence herbicide or as a directed spray in
the removal of weeds from specific areas. Although different plant species
have different degrees of susceptibility, pentachlorophenol cannot be con-
sidered a herbicide which possesses substantial specificity toward target
species. Thus, when spraying is required to remove target species growing
among crops, more effective alternatives for chemical weed control are
available. Also, pentachlorophenol is used as a defoliant and preharvest
desiccant. In tests by Bovey (1969), pentachlorophenol was the fastest-
acting desiccant among six contact herbicides.
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279
Pentachlorophenol applied at concentrations of 2 to 4 kg/ha caused
considerable malformation in crested wheatgrass seedlings (Klomp and Hull,
1968). Outdoor test plots were sprayed with pentachlorophenol, and samples
of the soil were removed at an unspecified time. These soil samples were
placed in plastic pots in a greenhouse and were seeded with crested wheat-
grass. Although yields were not reduced substantially, the grass displayed
epinasty, onion leaf, and other malformations.
D.4.2.2.2.2 Aquatic plants — Blackman et al. (1955) determined the
effect of pentachlorophenol on duckweed (Lemna minor). The index of tox-
icity used was the concentration of pentachlorophenol which caused chlorosis
in half the fronds. This value was 1.2 x 10 micromoles/liter or 0.32
mg/liter.
Dharukar (1973) studied the effect of pentachlorophenol on water
hyacinth (Eichhom-ia crassipes), Spraying ponds with sodium pentachloro-
phenate at a rate of 11.4 g/m2 effectively controlled water hyacinth.
Plants were sprayed in April, September, and December, and two months
after spraying 92%, 43%, and 78%, respectively, had died. Because applica-
tion was made on an area basis, the pentachlorophenol concentration could
not be computed. Reinfestation occurred, but all plants surviving the
treatment were stunted in growth and the formation of offsets was decreased.
D.4.2.2.3 Mitotic Effects — The effect of pentachlorophenol on root
tip mitosis and germination of pollen grains in water hyacinth was also
investigated by Dharurkar (1972). When root tips were cultured in solu-
tions of sodium pentachlorophenate, the percentage of cells undergoing
mitosis gradually decreased. The effect was dose related; 24 hr after
treatment with 250 mg/liter pentachlorophenol only 2% of the cells showed
mitotic activity. Chromosomal abnormalities such as stickiness of chromo-
somes, fragmentation, abnormal shapes of nuclei, grouping of chromosomes,
multinucleolation, and bridges were observed. Also, the percentage of
germinating pollen grains and the length of pollen tubes decreased as the
concentration of pentachlorophenol increased. No germination occurred
when plants were cultured at 6 mg/liter sodium pentachlorophenate.
Pentachlorophenol has caused abnormal mitosis in the European broad
bean (Vi-oia fdba). Amer and Ali (1969) demonstrated a positive effect of
pentachlorophenol on the number of mitotic anomalies as well as a consider-
able decrease in the mitotic index of root preparations of Vioia faba
(Table D.4.6). The degree of abnormality appeared to be dose related;
of the cells examined, 6%, 4.3%, and 2.3% were found to be abnormal at
dosages of 174, 87, and 43.5 mg/liter pentachlorophenol respectively.
D.4.2.2.4 Effect on Lipid Synthesis — Mann and Pu (1968) found an
effect of pentachlorophenol on lipid synthesis in the excised hypocotyls
of hemp sesbania [Sesbania exaltata (Raf.) Cory]. Concentrations of 1 to
20 mg/liter of pentachlorophenol were used, and the incorporation of
[C-14]malonate into lipids was monitored. A dose-related inhibition of
lipid synthesis by pentachlorophenol was noted; synthesis was 53% of
normal at 20 mg/liter pentachlorophenol. No inhibition mechanisms were
suggested.
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280
TABLE D.4.6. EFFECT OF PENTACHLOROPHENOL ON MITOTIC ABNORMALITIES
IN ROOT PREPARATIONS OF VICIA FABA
Cell type and
mitotic stage
Number of dividing cells
Number of abnormal cells
Abnormal cells, %a
Cells in prophase, %
Cells in metaphasej %
Abnormal cells in metaphase, %a
Cells in anatelophase, %
Abnormal cells in anatelophase, %a
Mitotic index
Control
669
10
1.52
62.0
19.9
4.51
18.1
3.30
98
43.5 mg/liter
pentachloro-
phenol
888
20
2.33
56.8
14.2
7.14
29.1
4.26
77
87 mg/liter
pentachloro-
phenol
1109
48
4.33
55.2
22.8
10.2
22.0
9.02
61
174 mg/liter
pentachloro-
phenol
522
31
6.00
48.1
29.5
12.3
22.4
10.3
39
Determined as ratio of abnormal cells to normal cells x 100.
Source: Adapted from Amer and Ali, 1969, Table 1, p. 534. Reprinted by permission of
the publisher.
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281
SECTION D.4
REFERENCES
1. Amer, S. M. , and E. M. All. 1969. Cytological Effects of Pesticides:
IV. Mitotic Effects of Some Phenols. Cytologia 34:533-540.
2. Blackman, G. E., M. H. Parke, and G. Carton. 1955. The Physiological
Activity of Substituted Phenols: I. Relationships between Chemical
Structure and Physiological Activity. Arch. Biochem. Biophys. 54:45-54.
3. Bovey, R. W. 1969. Effects of Foliarly Applied Desiccants on Selected
Species under Tropical Environment. Weed Sci. 17:79-83.
4. Carlson, L. W. , and L. D. Nairn. 1974-1975. Pentachlorophenol and
Captan Effects on Containerized Red and Jack Pine Seedlings. Tree
Plant. Notes 26(l):32-34.
5. Dharurkar, R. D. 1972. Effect of Herbicides on Root Tip Mitosis and
Germination of Pollen Grains of Eichhomia crassipes. Indian Sci.
Congr. Assoc. Proc. 59(3):363.
6. Dharurkar, R. D. 1973. Control of Eichhomia orassipes Mart. Indian
Sci. Congr. Assoc. Proc. 60:380.
7. Ferguson, E. R. 1959. Wood Treated with Penta Can Damage Pine Nursery
Seedlings. Tree Plant. Notes 38:21-22.
8. Ferree, D. C. 1974. Influence of Freshly Treated Posts on Growth of
Newly Planted Trees. Ohio Agric. Res. Dev. Cent. Res. Summ. 75:11-12.
9. Hilton, H. W., Q. H. Yuen, and N. S. Nomura. 1970. Distribution of
Residues from Atrazine, Ametryne, and Pentachlorophenol in Sugarcane.
J. Agric. Food. Chem. 18(2):217-220.
10. Kaufert, F. H., and K. A. Loerch. 1955. Treated Lumber for Greenhouse
Use. Minn. For. Notes 36:1-2.
11. Klomp, G. J., and A. C. Hull, Jr. 1968. Herbicidal Residues on Crested
Wheatgrass. Weed Sci. 16:315-317.
12. Mann, J. D., and M. Pu. 1968. Inhibition of Lipid Synthesis by Certain
Herbicides. Weed Sci. 16(2):197-198.
13. Miller, C. S., and M. M. Aboul-Ela. 1969. Fate of Pentachlorophenol
in Cotton. J. Agric. Food Chem. 17(6):1244-1246.
14. Takahashi, S. 1971. Studies on the Mechanism of Germination Inhibited
by Pentachlorophenol. Mem. Tokyo Univ. Agric. 14:1-27.
15. Weinbach, E. C. 1957. Biochemical'Basis for the Toxicity of Penta-
chlorophenol. Proc. Natl. Acad. Sci. U.S.A. 43:393-397.
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D.5 BIOLOGICAL ASPECTS IN WILD AND DOMESTIC ANIMALS
D.5.1 BIOLOGICAL ASPECTS IN BIRDS AND MAMMALS
D.5.1.1 Metabolism
D.5.1.1.1 Uptake and Absorption
D.5.1.1.1.1 Inhalation — Toxic responses in animals following the
inhalation of pentachlorophenol have been reported by Plakhova (1966).
Animals (species not stated) daily exposed for 4 hr to 23 mg pentachloro-
phenol per cubic meter of air for a period of four months showed decreases
in hemoglobin, weight, and erythrocytes with accompanying increases in
eosinophils and leucocytes. Exposure to a lower concentration of 7.44
mg/m3 resulted in unstable, insignificant changes.
D.5.1.1.1.2 Cutaneous absorption — Walters (1952) studied the ef-
fects of pentachlorophenol-treated wood on pigs and cattle. In two
separate experiments, pigs were confined to farrowing houses treated with
a 5% solution of pentachlorophenol in mineral spirits, a light solvent
that evaporates rapidly to leave a dry surface. In the first experiment,
a sow and two-week-old litters of 6 to 12 pigs were confined to farrowing
houses that had been treated with pentachlorophenol on the outside only.
These animals remained in the farrowing houses until the young pigs were
eight weeks old. The pigs displayed normal growth and showed no apparent
detrimental effects from the exposure. No tests were performed to deter-
mine if pentachlorophenol was absorbed internally by the pigs. In the
second experiment, the sows were allowed to farrow in houses treated in-
side and outside with pentachlorophenol. The treated houses were allowed
to air-dry for 30 days before the sows were placed in the buildings. The
sows and their litters were confined to the farrowing houses for at least
7 days and no ill effects were noted. Similarly, cattle exposed to penta-
chlorophenol-treated posts, gates, electric fence stakes, and corral tim-
bers for up to eight months were unaffected. The timbers were soaked in
a 5% solution of pentachlorophenol in No. 3 fuel oil. These experiments
do not rule out cutaneous absorption of pentachlorophenol, but they do
demonstrate that acutely or chronically toxic amounts of pentachlorophenol
were not absorbed by the cutaneous route.
In contrast to the data of Walters (1952), Schipper (1961) provided
evidence that pentachlorophenol can be cutaneously absorbed in acutely
toxic amounts. Extensive losses of baby pigs confined to farrowing pens
treated with pentachlorophenol occurred in North Dakota. The lumber was
treated with a formulation containing 4.37% pentachlorophenol, 0.63%
other chlorophenols, 81.6% petroleum distillate, and approximately 13.2%
inert ingredients. The wood was allowed to dry for one to five days before
it was used in the experiment. Direct skin contact by pregnant swine with
farrowing pens freshly treated with pentachlorophenol solutions produced
a toxic response which resulted in extensive mortality in newborn swine.
Insufficiently dried lumber saturated with pentachlorophenol was most
toxic. Direct contact of the pregnant sow with the freshly treated lumber
282
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283
apparently allowed sufficient skin absorption to cause extensive fetal
mortality and the birth of weak pigs. Furthermore, the presence of
pentachlorophenol on the teats and in the mammary glands apparently
discouraged nursing. The piglets were probably exposed to pentachloro-
phenol by three routes — inhalation of vapors, oral uptake from the teats,
and cutaneous contact with the treated wood. Autopsy of the piglets
revealed pathological lesions of the kidney, urinary bladder, liver,
spleen, stomach, and intestinal and respiratory tracts. In general,
mortality at birth was greatest for pigs born from sows confined to the
pentachlorophenol-treated pens for the longest time prior to farrowing
(Table D.5.1). The degree of toxicosis in young pigs depended on their
age at time of exposure (i.e., the older the pigs, the lower the toxic
effect). The extreme sensitivity at very early ages probably resulted
from an inability to excrete pentachlorophenol rapidly enough to prevent
systemic toxicity. The inclusion of bedding in the pentachlorophenol-
treated farrowing pens prevented the toxic response. The pentachloro-
phenol levels in the swine were not estimated.
TABLE D.5.1. MORTALITY OF PIGS FARROWED IN CRATES TREATED WITH PENTACHLOROPHENOL
Treatment
Dilute pentachlorophenol
Dilute pentachlorophenol
(factory-treated lumber)
Number
of litters
investigated
8
3
Number of
pigs in
litters
89
33
Number
dead on
delivery
5
5
Postf arrowing
deaths^
1/10, 2/4, 3/1
1/4, 3/4, 4/1, 6/1
Undiluted pentachlorophenol
Dilute pentachlorophenol
(factory-treated lumber
covered with straw)
Undiluted creosote
Distillate
Controls
2
4
1
4
19
41
11
36
0
24
0
1
1/1
1/6, 2/4,
None
1/1, 2/2
3/1
,Applied by brush unless otherwise described.
Numerator is number of days following delivery; denominator is number of pigs that
died on that day.
Both sows died before delivery.
Source: Adapted from Schipper, 1961, Table 1, p. 403. Reprinted by permission of
the publisher.
Another case of pentachlorophenol poisoning of newborn swine was
reported by Blevins (1965). Nine newborn pigs exposed to a newly con-
structed farrowing house which was improperly treated with pentachloro-
phenol died. The owners exceeded the manufacturer's recommendation in
treating the floor of the farrowing house with a solution of pentachloro-
phenol in crankcase oil, and no straw or shavings were provided as
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284
bedding. The author theorized "that these pigs received triple exposure
to the wood preservative: 1) by direct absorption through the skin; 2)
orally from the gilt's mammary glands, and 3) perhaps most severely, as
an aerosol in the hot, poorly ventilated farrowing house."
The effect of pentachlorophenol-creosote mixtures on the clipped
skin of calves was determined by Olafson and Leutritz (1959). Moderate
to severe local damage was evident as a dry, crusty thickening of the
skin seven to ten days following application. Healing was slow and
recovery was incomplete even after four weeks; possible systemic effects
were not determined.
D.5.1.1.1.3 Ingestion — Pentachlorophenol is repellent to animals.
Pasture treated with a herbicidal formulation of pentachlorophenol was
avoided by cattle (Grigsby and Farwell, 1950). The herbicide (contain-
ing 3.7 kg of pentachlorophenol in 106 liters of diesel fuel and emulsi-
fied with 76 liters of water) was applied to an acre of pastureland, and
livestock, including horses, dairy and beef cattle, sheep, and swine,
were tested for preference of treated or untreated areas. These animals
avoided the sprayed areas. Pentachlorophenol was applied at a rate two
to four times greater than the recommended herbicidal dosage. The authors
concluded that agricultural use of these materials for weed control in
pastures is a reasonably safe procedure. Despite the repellent character-
istics, cattle will drink pentachlorophenol solutions when they are thirsty.
Spencer (1957) reported fatal poisoning of a cow which drank an undeter-
mined amount of 5% pentachlorophenol in kerosene. He noted that both
kerosene and pentachlorophenol are toxic and that pentachlorophenol is a
tissue fixative that prevents fermentation in the rumen.
Walters (1952) "drenched" (force-fed) swine with 35 g of a solution
containing 5% pentachlorophenol, 5% diacetone alcohol, and 90% mineral
spirits. The dose rate was approximately 83 mg/kg, and the blood level
48 hr after dosing was 42 mg/liter. No apparent harmful effects occurred
in the swine; however, absorption across the gastrointestinal tract was
shown by analysis of several tissues during autopsy. The retention and
excretion of pentachlorophenol by these swine are shown in Table D.5.2.
Blood levels of pentachlorophenol in sheep force-fed pentachloro-
phenol-impregnated sawdust are shown in Table D.5.3 (Harrison, 1959).
The rapid initial rise in the pentachlorophenol concentration in the
blood indicated rapid absorption by the gut. Levels of pentachlorophenol
in the blood of animals that survived peaked in 3 to 6 hr following in-
gestion. Wide variability is evident in both the blood levels reported
and in the animals' responses to a pentachlorophenol dose. One sheep
administered a dose of 139 mg/kg died after 12 hr, but another receiving
an identical dose survived for 24 days, with pentachlorophenol levels in
the blood dropping to near zero.
D-5-1-1-2 Transport and Distribution - The transport and distribu-
tion of pentachlorophenol in experimental animals is discussed in detail
in Section D.6.1.2. It is assumed that data obtained from experimental
animals are directly applicable to domestic and wild animals, particularly
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285
TABLE D.5.2. RETENTION OF PENTACHLOROPHENOL
IN VARIOUS BIOLOGICAL MATERIALS FROM SWINE
DRENCHED WITH A SOLUTION CONTAINING 5%
PENTACHLOROPHENOL, 5% DIACETONE ALCOHOL,
AND 90% MINERAL SPIRITS
Biological
material
Pentachlorophenol content
(mg/100 g tissue or
mg/100 ml liquid)
30-g
Control pentachlorophenol
solution
Blood 0.10
Fat 1.00a
Feces
24-hr sample
48-hr sample
Kidney 0.10
Liver 0.60
Muscle 0.20
Urine
24-hr sample
48-hr sample
4.20
<0.05fc
0.60
3.06
0.60
0.58
0.10
18.4
21.2
Bad sample consisting of hair, hide, and
fat; poorly homogenized.
*Amounts less than 0.05 mg/100 g were not
detectable.
Source: Adapted from Walters, 1952,
Table 2, p. 305. Reprinted by permission of
the publisher.
TABLE D.5.3. VARIABILITY OF PENTACHLOROPHENOL
LEVELS IN BLOOD OF FIVE SHEEP FORCE-FED
PENTACHLOROPHENOL-IMPREGNATED SAWDUST
Time
after
dose
(hr)
2
4
8
12
16
24
a
b
Pentachlorophenol
blood (mg/liter) at
111 125
mg/kg mg/kg
30 25
50 a
45
40
35
30
Died in 4 hr.
139
mg/kg
40
40
38
c
level in
doses of
139
mg/kg
40
80
80
60
35
5
167
mg/kg
60
b
Died in 12 hr.
Source: Compiled from Harrison, 1959.
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286
mammals. Although transport and distribution of pentachlorophenol in
domestic animals have not been extensively studied, some data are avail-
able. Harrison (1959) studied levels of pentachlorophenol in the blood
of sheep force-fed pentachlorophenol-impregnated sawdust (Table D.5.3).
The liver of one sheep which died after ingesting 125 mg pentachlorophenol
per kilogram body weight contained 4 mg pentachlorophenol per 100 g wet
tissue (40 ppm). Walters (1952) investigated the tissue distribution
and excretion of pentachlorophenol in swine force-fed a solution of the
compound. The distribution of pentachlorophenol in the organs, feces,
and urine of these swine is shown in Table D.5.2. The kidney, which
showed a higher retention of pentachlorophenol than any other tissue,
contained six times more pentachlorophenol than the kidney of the control
animal. Only small amounts of pentachlorophenol were found in other
tissues as compared with levels in the control animal.
D. 5.1.1.3 Bio transformation — Information on the metabolism of
pentachlorophenol in birds and wild or domestic mammals is not available.
Considerable data are available, however, on the metabolic products of
pentachlorophenol degradation in experimental animals. This information
(as well as a proposed integrated pathway for pentachlorophenol metabolism
in mammals) is fully discussed in Section D.6.1.3. In summary, penta-
chlorophenol conjugates (including glucuronide conjugates), tetrachloro-
hydroquinone, tetrachlorohydroquinone conjugates, and chloranil appear to
be major products of pentachlorophenol metabolism in mammals. Metabolism
probably takes place primarily in the liver.
D.5.1.1.4 Excretion — Walters (1952) discussed the excretion of
pentachlorophenol by domestic animals. Large amounts of pentachloro-
phenol recovered in the urine and feces of animals force-fed pentachloro-
phenol indicated that the substance is rapidly excreted (Table D.5.2).
Most pentachlorophenol was excreted in the urine with smaller amounts
present in the feces. The 48-hr feces sample contained much more penta-
chlorophenol than the 24-hr sample. Although more pentachlorophenol was
excreted in the 48-hr than in the 24-hr urine sample, the amounts were
similar. Urinary excretion, at least over 48 hr, appeared to be rela-
tively constant. Fecal excretion appeared to peak at approximately 48 hr
following ingestion.
Zumwalt et al. (1977) determined the uptake and elimination of penta-
chlorophenol in dairy cows following 14 daily oral exposures of 0.05, 0.5,
or 5.0 mg/kg. Blood levels increased rapidly within 6 hr after dosing
and reached a plateau in approximately 6 days. Plateau values were 0.054
mg/liter (0.05 mg/kg dose), 0.494 ing/liter (0.5 mg/kg dose), and 2.432
ing/liter (5.0 mg/kg dose). Pentachlorophenol levels in serum decreased
rapidly when dosing stopped. The calculated half-life was less than 2
days. A linear relationship was found when log dose was plotted against
log plasma level after 14 days of exposure.
D.5.1.2 Effects
D-5-1'2'1 Physiological or Biochemical Role - No data suggest that
pentachlorophenol plays any normal physiological or biochemical role in
birds or mammals.
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287
D. 5.1.2.2 Toxicity — Both pentachlorophenol and sodium pentachloro-
phenate are toxic when tested in many animals. The factors which primarily
determine whether or not systemic toxicity will ensue are the dose and the
ability of the animal to excrete the substance. If doses are high enough,
pentachlorophenol is acutely toxic following a single administration; it
exhibits chronic toxicity when administered by any of three principal
routes.
D.5.1.2.2.1 Mechanism of action — The mechanism of toxic action of
pentachlorophenol has been extensively studied in experimental animals.
These data are presented in Section D. 6.2.2.1. It is assumed that the
data derived from experimental animal studies is directly applicable to
domestic mammals and birds which are exposed to pentachlorophenol. In
summary, pentachlorophenol uncouples oxidative phosphorylation, thus
short-circuiting the energy metabolism of the animal. At high dosages,
inhibition of other enzyme systems and gross cellular degeneration occur.
D.5.1.2.2.2 Local and systemic pathology — Application of sodium
pentachlorophenate powder to the skin of rabbits caused marked irritation
and even a chemical burn. Conversely, pentachlorophenol powder caused
only slight skin redness in the rabbit (Dow Chemical Company, 1969a,
19692?). However, pentachlorophenol in petroleum solvents has caused
serious skin damage and necrosis in experimental animals. Sows confined
to farrowing crates with wooden platforms to which undiluted pentachloro-
phenol was applied developed extensive abdominal burns and necrosis
following a 24-hr confinement (Schipper, 1961). A 2% pentachlorophenol
solution in creosote applied to the clipped skin of calves caused marked
changes which persisted for four weeks (Olafson and Leutritz, 1959).
Several cases of systemic toxicity of pentachlorophenol to farm
animals have been reported. Symptoms of severe pentachlorophenol poison-
ing are hyperpyrexia, depression, rapid respiration, weakness, death
without struggle, and rapid onset of rigor mortis following death (Spencer,
1957; Schipper, 1961; Blevins, 1965).
In experiments conducted by Schipper (1961), swine were confined to
farrowing pens which had been freshly treated with a pentachlorophenol
formulation. Neonatal mortality among the litters of swine confined to
the treated pens was extensive. Autopsy results of the fatally poisoned
animals indicated the following pathological changes: severe lesions of
the kidney including subcapsular fluid and hemorrhages, congestion of the
liver and spleen, congestion and inflammation of the stomach and intestinal
tract along with the consistent presence of large amounts of gas, necrosis
of the respiratory tract as well as congestion and mild emphysema, an
abnormal fluid in the urinary bladder which was white, tenacious, and
contained fibrinous threads, and, finally, various local lesions on the
skin and in the oral cavity.
Harrison (1959) administered lethal doses of pentachlorophenol to
sheep and calves in the form of pentachlorophenol-impregnated sawdust.
Postmortem findings included enlarged edematous lymph nodes; collapsed
and generalized congestion of the lungs; mild congestion (in some animals)
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288
of the stomach, intestines, liver, and kidney; and, occasionally, hemor-
rhages in the epicardium and along the aorta. Pathological changes in
pentachlorophenol-poisoned experimental animals and humans are discussed
on the basis of individual organs in Section D.6.2.2.2.
D.5.1.2.2.3 Acute toxicity — A limited number of reports on the
acute toxicity of pentachlorophenol to domestic mammals and wildlife are
available. Minimum lethal doses and LD5o values have been reported for
experimental animals (Section D.6.2.2.3).
Spencer (1957) discussed the fatal poisonings of two Hereford cows.
Drinking water in the pasture where the fatalities occurred was at a
considerable distance, but an open barrel of 5% pentachlorophenol in
kerosene was found at the scene. The diagnosis was poisoning caused by
the consumption of pentachlorophenol in kerosene. Because both kerosene
and pentachlorophenol are toxic, the exact contribution of pentachloro-
phenol to the deaths is unclear. Another case of livestock poisoning
involved swine confined to farrowing pens treated with pentachlorophenol.
Ten neonatal pigs confined for 24 hr in a farrowing pen treated with
pentachlorophenol as a wood preservative died (Blevins, 1965). The owners
had improperly treated the farrowing pens with excessive doses of penta-
chlorophenol, and no bedding was provided, allowing constant cutaneous
contact with the pentachlorophenol-treated wood. Autopsy results revealed
grossly congested and distended lungs and pronounced cardiac and renal
petechiation.
The investigations undertaken by Schipper (1961) were prompted by
extensive losses of baby pigs in the immediate area of his laboratory.
The hazard involved in confining swine to pens freshly treated with
pentachlorophenol was demonstrated conclusively. In these experiments,
swine were confined to farrowing pens which had been treated with a 4%
solution of pentachlorophenol in petroleum distillate. Pig mortalities
were high and increased with length of confinement. Neonatal mortality
among the litters confined to pentachlorophenol-treated farrowing pens
was extensive. The surviving animals showed a pronounced inability to
gain weight until they were approximately five to six weeks old (Table
D.5.4). This low weight gain was attributed to continuous cutaneous
uptake of pentachlorophenol from the farrowing pen, inadequate nursing
due to pentachlorophenol contamination of the mothers' teats, and direct
pentachlorophenol ingestion.
Harrison (1959) studied the toxicity of pentachlorophenol to calves
and sheep (for chronic toxicity data, see Section D.5.1.2.2.4). Because
the purpose of this investigation was to evaluate the hazard posed by
pentachlorophenol-treated wood, pentachlorophenol was administered to
animals in the form of impregnated sawdust. Dry Douglas fir (Pseudotsuga
tanfolid) sapwood was "loaded" with pentachlorophenol at a rate of 320 kg
of pentachlorophenol solution per cubic meter of wood. The solution con-
tained 5% pentachlorophenol in a petroleum solvent. Standard loading for
larch (tox sp.) and Douglas fir posts is 112 kg/m3; therefore, a load-
ing of 320 kg/m was adopted to approximate the amount in the outside
layers of posts (the region which is most likely to be ingested by animals)
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289
TABLE D.5.4. COMPARISON OF AVERAGE WEIGHT OF PIGS INVOLVED IN EXPERIMENTS TO
DETERMINE TOXIC ITY OF PENTACHLOROPHENOL
Average weight (kg)
_ Number -- — - --
Treatment
..
of pigs Birth 7 daYs 21 daYs 42
old old old
Farrowing pens treated with 4%
pentachlorophenol— petroleum
distillate formulation 141 1.54 2.77 5.58 10.99
Control 36 1.44 3.76 9.39 11.49
Source: Adapted from Schipper, 1961, Table 2, p. 404. Reprinted by permis-
sion of the publisher.
The minimum acute lethal dose of pentachlorophenol to sheep was approxi-
mately 120 mg pentachlorophenol per kilogram body weight. The acute
lethal dose for calves was estimated to be 140 mg pentachlorophenol per
kilogram body weight. Acute poisoning resulted in deaths from 2 to 14 hr
following onset of symptoms. The most prominent symptom reported was an
accelerated breathing rate. Badly affected animals swayed, panted noisily
with head lowered, and made little or no attempt to move away when ap-
proached. Recovery was rapid and complete if force-feeding was stopped
at this stage of poisoning. In fatal cases, complete collapse occurred;
the animals lay limp and panted vigorously through open mouths. Rigor
mortis set in with extreme rapidity, and the body became completely rigid
within 1 or 2 min after death. Proteinuria and the presence of reducing
sugars in the urine were reported for some animals. Postmortem findings
included enlarged edematous lymph nodes, collapse and generalized con-
gestion of the lungs, mild congestion (in some animals) of the stomach,
intestines, liver, and kidney, and occasionally, hemorrhages in the
epicardium and along the aorta.
Extensive loss of wildlife was reported by Vermeer et al. (1974)
following the widespread application of sodium pentachlorophenate as a
molluscicide in Surinam, South America. The incident occurred on an
8000-ha rice-growing project at Wageningen in the western coastal region
of Surinam. The sodium pentachlorophenate was applied widely to the rice
fields for control of water snails (Pomaoea glauoa and P. l-ineata) which
damage young rice plants. A total of 50,000 kg was applied to the rice
fields from 1965 to 1971, giving a pentachlorophenol concentration of
approximately 4 kg/ha. An investigation took place from October to
December 1971 following the extensive spraying of sodium pentachloro-
phenate. The deaths of fish, frogs, snails, and birds were recorded,
and the pentachlorophenol residues in the dead organisms were determined
(Table D.5.5). Concentrations of pentachlorophenol in dead fish ranged
from 31 to 59 mg/kg. Residue levels of 37 mg/kg were found in dead
snails. Concentrations of pentachlorophenol in fish collected live from
unsprayed ditches were also substantial, ranging from 2 to 13 mg/kg.
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TABLE D.5.5.
PENTACHLOROPHENOL IN COMPOSITE SAMPLES OF SNAILS, FROGS, AND FISH COLLECTED IN
RICE FIELDS AT WAGENINGEN, SURINAM, NOVEMBER 1971
. Sample
SPecies description
Number of
animals
Fat in
animals
(%)
Pentachlorophenol
residue
(pg/g wet wt)
Snails (Pomaoed)
Frog (Pseudis paradosca)
Fish
Dead after sodium penta-
chlorophenate application
Dead after sodium penta-
chlorophenate application
10
6
4.0
5.2
36.8
8.1
ro
VO
o
Kwi kwi (Hoplosternum Httorale)
Srieba
Krobia
(Astyanax b-imaaulatus)
(Ciohlasoma bimaculatwn)
Dead after sodium penta-
chlorophenate application
Alive from unsprayed ditches
Dead after sodium penta-
chlorophenate application
Alive from unsprayed ditches
Dead after sodium penta-
chlorophenate application
Alive from unsprayed ditches
8
5
8
10
8
8
7.9
6.4
7.5
8.4
5.2
5.2
41.6
13.4
59.4
1.77
31.2
8.76
Source: Adapted from Vermeer et al., 1974, Table 8, p. 228. Reprinted by permission of the publisher.
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291
Vermeer et al. (1974) also reported that 50 snail kites (birds that
feed almost exclusively on snails) were found dead between November 28
and December 4, 1971, after a period of intensive application of sodium
pentachlorophenate in November. It was concluded that the kites died
from pentachlorophenol poisoning. Seventeen of the 50 dead birds were
sampled for pentachlorophenol residues in brain, liver, and kidney
(Table D.5.6). The organochlorine insecticides —DDT, dieldrin, and
endrin — were present at very low or undetectable concentrations, but
the mean concentration of pentachlorophenol was comparatively high.
Living birds were also analyzed for pentachlorophenol content. Table
D.5.7 gives the residue levels in birds found foraging in the rice fields
as well as values for birds which were seen foraging in an untreated
freshwater marsh. The difference in pentachlorophenol levels in tissues
is evident. Other species of birds that habitually frequented the rice
fields were also sampled (Table D.5.8). All of the samples contained
detectable concentrations of pentachlorophenol. The death of the snail
kites resulted from their consumption of snails containing pentachloro-
phenol. The substantial levels of pentachlorophenol noted in other birds
indicated that pentachlorophenol contamination of wildlife in the area
was fairly widespread. The effect of these sublethal pentachlorophenol
levels in wildlife was not determined. The use of sodium pentachloro-
phenate to control snails makes neither economic nor ecological sense
because pentachlorophenol apparently poses a hazard to snail kites, a
species of bird which feeds exclusively on snails that damage young rice
plants. Thus, the use of sodium pentachlorophenate interferes with
rather than reinforces the natural predation on snails. Vermeer et al.
(1974) recommended that, despite the high cost, Bayluscide (a 1:1 mix-
ture of 2,5-dichloro-4-nitrosalicylanilide and 2-aminoethanol) be sub-
stituted whenever possible for sodium pentachlorophenate.
Hill et al. (1975) determined the dietary toxicity of pentachloro-
phenol in four species of young birds. Pentachlorophenol was added to
the diets at various levels, and the LC50 values were determined after
TABLE D.5.6. PESTICIDE RESIDUES IN 17 SNAIL KITES FOUND DEAD AT A ROOST ADJACENT
TO RICE FIELDS AT WAGENINGEN, SURINAM, NOVEMBER 27-28, 1971
Number
nf
birds
17
17
10
™- Fat in
Tissue
, , tissue
analyzed ,„,.
Brain 4.83 ± 0.88
Liver 4.29 ± 0.58
Kidney 1.35 ± 0.31
Mean residue ± standard error
(ug/g tissue wet wt)
Penta-
Total DDT Dieldrin Endrin chlorophenol
<0.01 <0.01 <0.01 11.25 ± 1.11
0.01 ± 0.006 0.03 ± 0.01 <0.01 45.56 ± 2.18
<0.01 <0.01 <0.01 20.34 ± 1.25
Source: Adapted from Vermeer et al., 1974, Table 10, p. 230. Reprinted by permis-
sion of the publisher.
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292
TABLE D.5.7. COMPARISON OF PENTACHLOROPHENOL RESIDUES IN SNAIL KITES
FORAGING IN PENTACHLOROPHENOL-TREATED RICE FIELDS AND THOSE IN A FRESHWATER
MARSH AT WAGENINGEN, SURINAM, NOVEMBER 29 - DECEMBER 3, 1971
Foraged in rice fields
Foraged in freshwater marsh
Number
of
birds
3
3
3
Tissue
analyzed
Brain
Liver
Kidney
Fat in
tissue
/ a/ \
\'° )
4.2
2.0
1.1
Pentachlorophenol
content
(yg/g wet wt)
2.11
10.4
16.6
Fat in
tissue
fV\
\ n )
6.0
2.7
0.6
Pentachlorophenol
content
(yg/g wet wt)
0.04
0.14
0.10
Source: Adapted from Vermeer et al., 1974, Table 11, p. 231. Reprinted by
permission of the publisher.
five days of feeding. The LC50 values reported were as follows: bob-
white, about 3400 ppm; Japanese quail, 5204 ppm; ring-necked pheasant,
4331 ppm; and mallard duck, about 4500 ppm. These values fell in cate-
gories IV and V in a five-level classification system; class V is re-
garded as practically nontoxic. By comparison, dieldrin was 24 to 87
times more toxic in this test system.
D. 5. 1.2. 2. 4 Chronic toxicity - Investigations have been made of the
systemic effects and levels of pentachlorophenol in the blood and urine
following chronic or repeated doses of the compound or its sodium salt
to domestic animals. Harrison (1959) studied the chronic toxicity of
pentachlorophenol-impregnated sawdust on calves and sheep (for acute
toxicity data, see Section D. 5. 1.2. 2. 3) . Dry Douglas fir (Pseudotsuga
tamfoUa) sapwood was impregnated with 320 kg of a 5% pentachlorophenol
solution per cubic meter of wood. Animals were daily force-fed impreg-
nated sawdust and were observed for signs of systemic toxicity. Adverse
cumulative effects in sheep as reflected by loss of body weight and
deterioration in general condition were caused by daily intakes of 27.8
to 55.6 mg pentachlorophenol per kilogram body weight (Table D.5.9).
The lowest daily dose rate which caused noticeable systemic effects was
27.8 mg/kg. In a similar test, the minimum toxic dose rate of penta-
chlorophenol to calves was estimated to be 35 mg/kg body weight (Table
D.5.10). Studies of body weight changes in sheep were inconclusive.
One animal receiving a daily dose of 13.9 mg/kg gained approximately
£ kg over an 18-day period. The control animal gained approximately 18
kg over this same period. A third animal receiving 27.8 mg/kg daily
gained approximately 22 kg.
Leutritz (1959>
chloroh aon o ec
chlorophenol in creosote was fed to cattle for two months.
the effect of a creosote-penta-
of 2% technical penta-
A 135-kg
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293
TABLE D.5.8. PENTACHLOROPHENOL RESIDUES IN COMPOSITE TISSUE SAMPLES OF BIRDS AND
SPECTACLED CAIMAN COLLECTED ON RICE FIELDS AT WAGENINGEN, SURINAM
OCTOBER 21-31, 1971
Species
Snail kite (Rostrhamus sociabilis)
Black vulture (Copajyr-s atratus)
Common egret (Egretta alba)
Snowy egret (Egretta thula)
Cattle egret (Ardeola ibis)
Purple gallinule (Porphyrula martiniod)
Spectacled caiman (Caiman orocodilus)
Number
of
birds
5
5
5
5
10
10
10
10
10
10
10
10
10
10
Tissue
analyzed
Brain
Liver
Brain
Liver
Brain
Liver
Brain
Liver
Brain
Liver
Brain
Breast muscle
Brain
Liver
Fat in
tissue
(%)
6.5
2.5
4.8
3.1
6.0
2.8
5.2
2.0
5.5
3.2
6.0
4.8
7.2
4.4
Penta-
chlorophenol
content
(ug/g wet vt)
0.10
0.19
0.09
0.06
0.08
0.14
0.10
0.19
0.49
0.07
0.10
0.04
0.18
0.24
Source: Adapted from Vermeer et al., 1974, Table 7, p. 226. Reprinted by permission of
the publisher.
calf was able to tolerate 0.45 kg of this formulation over a two-month
period without showing appreciable detrimental effects. Grigsby and
Farwell (1950) tested the effect on livestock of pentachlorophenol in a
mineral oil emulsion used as a herbicide on grazing land. Horses, dairy
and beef cattle, sheep, and swine avoided areas sprayed with a penta-
chlorophenol formulation; the animals invariably preferred grazing on
unsprayed pasture. These authors therefore concluded that the use of
pentachlorophenol as a herbicide on pastureland is a relatively safe
procedure because livestock preferentially avoid sprayed areas.
Herdt, Loomis, and Nolan (1951) tested the effect of sodium penta-
chlorophenate on cattle. The investigation was undertaken to test the
feasibility of using sodium pentachlorophenate as a molluscicide. The
substance was administered to three young bulls in drinking water at
daily dose rates of 7.6 mg/kg for a minimum of five weeks. Pulse, res-
piration rate, temperature, urine analyses, and blood counts were moni-
tored, and no significant deviations from normal were found. Furthermore,
no toxic manifestations were evident on autopsy of the animals. They con-
cluded that the use of sodium pentachlorophenate as a molluscicide in the
field is a relatively safe procedure if reasonable precautions are taken
in its application.
The effect on swine, sheep, and cattle of preservative-treated
gates, watering troughs, feed troughs, salt boxes, posts, electrical
fence stakes, and corral timbers was tested by Walters (1952). The
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294
TABLE D.5.9. CHRONIC TOXICITY DOSE RATES AND EFFECTS OF
PENTACHLOROPHENOL ON TREATED SHEEP
Daily dose of
pentachlorophenol
(mg/g) (g)
13.9 0.32
27.8 0.71
55.6 1.50
Weight of
treated
sawdust
(g)
13
29
61
Number
of
doses
19
19
19
Effect
None
Slight
Symptoms and severe
84
12
loss of body weight
None
Source: Adapted from Harrison, 1959, Table 2, p. 90. Reprinted
by permission of the publisher.
TABLE D.5.10. CHRONIC TOXICITY DOSE RATES AND EFFECTS
OF PENTACHLOROPHENOL ON TREATED CALVES
Daily dose of
pentachlorophenol
(mg/kg)
35
50
(g)
4.16
6.60
Weight of
treated
sawdust
(g)
168
267
Number
of
doses'2
11
9
Effect
Temporary check in growth
Severe loss of weight and
70
10.90
442
in general condition
Died 4 hr after second dose
"Limited by the sawdust available.
Source: Adapted from Harrison, 1959, Table 4, p. 91. Reprinted by
permission of the publisher.
treated items were cold-soaked in the preservative solution consisting
of 5% pentachlorophenol in a mineral spirit solvent for a maximum of
48 hr. The sheep exposed to the treated equipment for two weeks showed
no ill effects. No attempt was made to determine whether or not penta-
chlorophenol entered the animal by ingestion. Exposure of calves to the
treated wood for one month apparently caused no detrimental effects.
Again, pentachlorophenol levels in the bodies of the animals were not
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295
determined. The length of time these animals were exposed to the penta-
chlorophenol-treated equipment does not appear to be sufficient to
evaluate long-term effects.
D.5.1.2.3 Carcinogenicity, Teratogenicity, and Mutagenicity — No
information is available on possible carcinogenic, teratogenic, or
mutagenic effects of pentachlorophenol in birds and domestic mammals.
A tumor-promoting effect of pentachlorophenol following application of
dimethylbenzanthracene to the skin of mice has been reported (Section
D.6.2.3), but it is not known whether this effect will occur in birds
or domestic animals.
D.5.1.2.4 Musty Taint — A problem of economic importance has
recently surfaced in the broiler chicken industry in England. The
problem involves the presence of a musty taint in chicken and chicken
eggs. Curtis et al. (1972, 1974) have found that the cause of this musty
taint is the presence of 2,3,4,6-tetrachloroanisole and pentachloroanisole
in broiler chickens. The anisoles are found in substantial quantities in
wood shavings used as bedding in the cages of chickens. They apparently
are formed in the litter as a result of methylation of the parent chloro-
phenols (including pentachlorophenol) by fungi present in the litter.
Although the primary offender causing musty taint appears to be tetra-
chloroanisole, pentachloroanisole may be the causative agent at much
higher concentrations (1000 times). The widespread use of pentachloro-
phenol and tetrachlorophenol as wood preservatives apparently results in
the presence of a substantial amount of these compounds in wood shavings
used for bedding of chickens. It has also been suggested that tetra-
chlorophenol may arise from dechlorination of pentachlorophenol (Parr et
al., 1974). Odor thresholds for pentachloroanisole and tetrachloro-
anisole are remarkably low (Table D.5.11). Samples of litter where musty
taint of chickens has been noted showed levels of pentachloroanisole and
tetrachloroanisole to be 5 mg/kg. The mode of entry of these compounds
into the birds has not been established (Curtis et al., 1972). Penta-
chlorophenol and tetrachlorophenol were found in freshly sawn lumber at
levels of 40 to 100 mg/kg. Parr et al. (1974) did not favor the view
that prevalent concentrations of tetrachlorophenol in wood shavings
result from dechlorination of pentachlorophenol (Table D.5.12). Rather,
they believed that the prevalence of tetrachlorophenol in wood shavings
is due to the more common use of this compound as a wood preservative.
They stated, "Although pentachlorophenol is generally thought to be more
widely used than 2,3,4,6-tetrachlorophenol as a wood preservative this
is not supported by these results. Technical grade pentachlorophenol
contains 10 to 20% of 2,3,4,6-tetrachlorophenol (and the converse is
true) but neither this nor the variable recoveries obtained for penta-
chlorophenol would explain the values observed. It is possible, but
unlikely, that some selective conversion of pentachlorophenol to 2,3,4,6-
tetrachlorophenol occurs at some stage before the shavings are sampled
but it seems more likely that the use of 2,3,4,6-tetrachlorophenol as^a
preservative against sap-stain is greater than is generally realised."
Removal of chickens from contaminated litter several days before slaugh-
ter prevents musty taint (Curtis et al., 1974). Curtis et al. (1972)
commented, "In this case the extremely low sensory thresholds of the
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296
TABLE D.5.11. DETECTION THRESHOLDS FOR
CHLOROANISOLES IN AQUEOUS SOLUTION^
Threshold
Compound concentration
(yg/g solution)
Pentachloroanisole 4 x 10~3
2,3,4,6-Tetrachloroanisole 4 x 10~6
2,4,6-Trichloroanisole 3 x 10~°
2,3,6-Trichloroanisole 3 x 10~10
Tests were made with 23 subjects in trip-
licate and are significant at the 1% level.
Source: Adapted from Curtis et al., 1972,
Table 1, p. 223. Reprinted by permission of
the publisher.
TABLE D.5.12. CHLOROPHENOL AND CHLOROANISOLE LEVELS IN
FRESH SHAVINGS AND SPENT LITTER FROM BROILER CHICKEN HOUSES
Chlorophenol or
chloroanisole
Sample Compound , level
(yg/g wet wt)
Fresh shavings
Spent litter
Pentachlorophenol
2,3,4, 6-Tetrachlorophenol
Pentachlorophenol
2,3,4, 6-Tetrachlorophenol
2,3,4, 6-Tetrachloroanisole
Pentachloroanisole
Mean
12
54
0.3
0.7
0.5
0.03
Range
0.6-83
4-310
0-4.1
0-5.6
0-3.6
0-0.3
Source: Adapted from Parr et al., 1974, Table 1, p. 838.
Reprinted by permission of the publisher.
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297
chloroanisoles...are fortunate because they probably discourage the
consumption of chickens containing these compounds, the toxicities of
which have not yet been established."
D.5.2 BIOLOGICAL ASPECTS IN FISH AND OTHER AQUATIC ORGANISMS
D.5.2.1 Metabolism
D.5.2.1.1 Uptake and Absorption — Fish and other aquatic organisms
can absorb pentachlorophenol through the gills, the gastrointestinal tract,
or directly through the body surfaces; absorption through the gills and
ingestion are the most likely routes of uptake. Because it is impossible
to differentiate between pentachlorophenol that enters the fish as a result
of absorption from the water and that which is ingested, these two routes
of uptake are considered together. No studies which discussed uptake of
pentachlorophenol via ingestion by fish or aquatic organisms were found;
therefore, it is assumed that the effects noted following uptake of the
compound from the water apply to all routes of uptake.
Pentachlorophenol accumulates in aquatic organisms (Rudling, 1970).
Tissue levels 100 to 1000 times the levels of ambient pentachlorophenol
in water have been found in fish taken from a lake into which pulp mill
effluents were discharged (Table D.5.13). The eel, a species with a high
fat content, acquires higher levels of pentachlorophenol than species with
a more normal fat content. The propensity of pentachlorophenol, and other
organochlorine compounds, to accumulate in the fatty tissue of aquatic
organisms is of serious concern because this allows the buildup of toxic
substances throughout the food chain. Rainbow trout readily remove penta-
chlorophenol from the surrounding water (Tsuda and Kariya, 1963) (Figure
D.5.1). The short-necked clam (Tapes phil-ippinarum) (Kobayashi, Akitake,
TABLE D.5.13. PENTACHLOROPHENOL LEVELS IN FISH AND
WATER DOWNSTREAM FROM A PULP MILL
Sample
Pentachlorophenol
content
(pg/liter) (yg/kg)
Water
Immediately downstream from mill 9
Receiving lake 3
Fish
Pike (Esox lucius) 200
Perch (Peroa fluwLat-ilis) 150
Eel (Anguilla anguilla) 3000
Source: Adapted from Rudling, 1970, Table 5, p. 536.
Reprinted by permission of the publisher.
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298
ORNL-OWG 78-105(1
1.0,
0.9 -
0.8 —
O
5 0.6
I
Q_
O
cr
o
4 0.5
0.4
0.3
0.2
• 0.98 mg/l ter
O 0.49 mg/liTer
20
40 60 80 100
TIME OF EXPOSURE Cmin)
120
Figure D.5.1. Decrease of pentachlorophenol concentration in water
during culture of rainbow trout. Source: Adapted from Tsuda and Kariya,
1963, Figure 1, p. 830. Reprinted by permission of the publisher.
and Tomiyama, 1969), the eel (Anguilla anguilla L.) (Holmberg et al.,
1972), and the goldfish (Carassius auratus) (Kobayashi and Akitake,
1975a) also remove pentachlorophenol.
A rapid decrease in pentachlorophenol concentration during culture
of the short-necked clam was not accompanied by a quantitatively equal
accumulation in this shellfish. Furthermore, pentachlorophenol levels
in the shellfish decreased with time without a concomittant increase in
the concentration of pentachlorophenol in the water (Kobayashi, Akitake,
and Tomiyama, 1970a). These results can be explained by a detoxification
mechanism in the shellfish (Section D.5.2.1.3).
Kobayashi and Akitake (1975a) exposed goldfish to [1AC]sodium penta-
chlorophenate at levels of 0.1, 0.2, and 0.4 mg/liter (Figure D.5.2).
Fish exposed to 0.1 mg/liter showed no evidence of adverse effects, al-
though pentachlorophenol concentrations increased with time, reaching a
peak of 90 yg/g. This increase represents a concentration factor from
the original pentachlorophenol medium of 1000 following a 120-hr exposure.
The fish exposed to 0.2 mg/liter pentachlorophenol showed a similar
accumulation with time; however, accumulation was more rapid. After the
concentration in the fish reached a level of about 100 yg pentachloro-
phenol per gram body weight, some of the fish died. No surviving fish
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299
<200
i
-------
TABLE D.5.14. DISTRIBUTION OF PENTACHLOROPHENOL IN THE SHORT-NECKED CLAM (TAPES PHILIPPINARUM)
Pentachlorophenol content
Seawater with
[ ''"Cjpentachlorophenol
Organ
Bo j anus ' organ
Liver
Digestive tract
Gills
Remainder
Whole body
(ug/g)
70
20
19
8
8
9
24 hr
(% of
whole-body
burden)
7
8
7
11
67
100
(ug/g)
85
10
10
4
3
4
48 hr
(% of
whole-body
burden)
10
10
8
12
60
100
(ug/g)
53
4
2
1.8
1.0
2.0
Normal seawater
8 hr
U of
whole-body
burden)
23
10
5
14
48
100
(yg/g)
32
4
0.5
1
0.8
1.5
24 hr
(% of
whole-body
burden)
23
20
1
9
47
100
a
Cultured in seawater treated with [l6C]pentachlorophenol; transferred at 48 hr to normal seawater.
Source: Compiled from Kobayashi, Akitake, and Tomiyama, 1969.
UJ
o
o
-------
301
freshwater or saltwater were exposed to 0.1 mg/liter sodium pentachloro-
phenate and were subsequently transferred to a medium free of pentachloro-
phenol. Levels of pentachlorophenol in the tissues were monitored during
the recovery period (Figure D.5.3). The highest pentachlorophenol levels
were found in the liver of eels exposed either to freshwater or saltwater
A positive relationship was found between exposure time and maximum levels
of pentachlorophenol in the tissues (4 days in freshwater and 8 days in
seawater). During the recovery period for the freshwater eels, levels of
pentachlorophenol in the tissues decreased; however, treated animals still
had about 1.2 ug/g in the liver and 0.08 yg/g in the muscle after 55 days.
These results do not prove conclusively, however, that pentachlorophenol
has a long half-life in eels. This experiment lacked two crucial controls.
The untreated water was not analyzed for pentachlorophenol content. From
previous reports of the ability of fish and eels to concentrate pentachloro-
phenol by 200 to 1000 times, trace amounts of contamination could possibly
account for part of the tissue residues at the end of the trial. Also,
although control eels were placed in the untreated water, tissue residues
were not reported. Additionally, freshwater and saltwater eels reportedly
contained pentachlorophenol in tissues before the experiment started.
Levels were 1.0 mg/kg in the liver and 0.2 mg/liter in the blood of sea-
water eels and 0.08 mg/kg in the liver and 0.02 mg/liter in the blood of
freshwater eels. Although differences in rates of uptake in the two
ORNL-DWG 78-10513
• LIVER
A MUSCLE
O BLOOD
1 5 8 12 16 148
16
TIME (days)
Figure D.5.3. Pentachlorophenol levels in various tissues of eels
from seawater and freshwater tests. Source: Adapted from Holmberg et
al., 1972, Figure 1, p. 175. Reprinted by permission of the publisher.
-------
302
media were not clear, the authors suggested that the more rapid action in
freshwater may have resulted from the difference in pH between seawater
and freshwater. The pH of water is known to affect ionization of phenols,
which would thereby affect pentachlorophenol uptake. The lipids, where
most of the stored pentachlorophenol appeared, were suggested as a source
for pentachlorophenol redistribution.
Kobayashi and Akitake (19752?) studied the turnover of absorbed
pentachlorophenol in various tissues of the goldfish (Carassius auratus') .
Pentachlorophenol levels in the tissues were examined during active
absorption from a pentachlorophenol-containing medium, and subsequent
excretion was determined with the fish in running water. Goldfish were
placed in a medium containing [1AC]pentachlorophenol (pentachlorophenol
at 0.2 mg/liter) ; the fish were then removed at 1, 5, 12, and 24 hr
following initiation of treatment, and selected tissues were analyzed
for pentachlorophenol (Table D.5.15). Other fish subjected to a 24-hr
exposure to pentachlorophenol were placed in running water, and tissue
samples were analyzed after recovery periods of 1, 5, 12, and 24 hr
(Table D.5.16). Pentachlorophenol accumulation in the gallbladder reached
values of 539 yg/g following the 24-hr exposure. A further increase was
seen even after the fish were transferred to clean running water for 24 hr.
In contrast, the pentachlorophenol content of other tissues decreased fol-
lowing transfer to running water. Pentachlorophenol in the gallbladder
eventually reached a peak of 1077 yg/g, which corresponded to a concentra-
tion factor of 5400 over the pentachlorophenol content of the medium. In
fact, pentachlorophenol in the gallbladder accounted for 41% of the total
pentachlorophenol detected in the fish after the transfer to running water
for 24 hr. Tables D.5.15 and D.5.16 show that relatively high amounts of
pentachlorophenol accumulated in the blood and the gills during early
periods of exposure (19% and 8% respectively). These amounts subsequently
declined to levels of 11% and 4% at the end of the excretion period.
Amounts in the kidney and hepatopancreas, however, were almost constant
during the absorption and excretion phases. A small increase in the
specific activity of lllC occurred in the gallbladder with time, indicating
decomposition of some of the pentachlorophenol in the fish. The authors
suggested that pentachlorophenol was detoxified following transfer to the
hepatopancreas and was partly transported to the gallbladder and the bile.
In a later study, Akitake and Kobayashi (19752?) demonstrated that penta-
chlorophenol is excreted by goldfish as a sulfate conjugate (Section
D.5.2.1.4).
Glickman et al. (1977) demonstrated that rainbow trout exposed to
25 yg/liter pentachlorophenol for 24 hr accumulated the following levels
in tissues: liver, 16 mg/kg; blood, 6.5 mg/liter; fat, 6.0 mg/kg; and
muscle, 1 mg/kg. Elimination half-lives were as follows: blood, 6.2 hr;
liver, 9.8 hr; fat, 23 hr; and muscle, 6.9 hr. Trout did not methylate
pentachlorophenol (i.e., did not form pentachloroanisole which has a
higher affinity for fat and a much longer tissue half-life) . The only
metabolite found in bile was the glucuronide conjugate.
Pruitt, Grantham, and Pierce (1977) found that bluegill (Lepomis
naeroch^ruS) placed in water containing 0.1 mg/liter pentachlorophenol
-------
TABLE D.5.15. CHANGES IN AMOUNT OF PENTACHLOROPHENOL ACCUMULATED IN GOLDFISH TISSUES DURING
EXPOSURE TO A MEDIUM CONTAINING 0.2 mg/liter ['^C]PENTACHLOROPHENOL
Pentachlorophenol content at exposure time of
Tissue
Gills
Blood
Hepatopancreas
Gallbladder
Kidney
Spleen
Heart
Testis
Ovary
Air bladder
Digestive tract
Brain
Muscle
Vertebra
Skin
Scale
Remainder
Whole body
(ug/g
t Issue)
4.2
9.7
2.4
NDa
ND
ND
ND
ND
0.57
ND
1.5
ND
0.78
ND
2.9
3.5
1.2
1.5
1 hr
(% of
whole-body
burden)
8.0
19.0
7.8
ND
ND
ND
ND
ND
2.3
ND
3.6
ND
12.0
ND
3.8
1 0 . 3
33.3
(ug/g
tissue)
10
32
11
43
19
ND
17
2.7
2.7
7.6
8.9
9.H
2.1
4.8
9.0
8.2
2.3
4.7
5 hr
(% of
whole-body
burden)
5.8
20.4
10.2
3.3
2.6
ND
0.8
0.6
4.7
0.9
5.8
0.7
1 0 . 1
1.5
3.6
7.9
20.9
(ug/g
tissue)
19
55
18
216
39
17
29
7.4
10
17
23
14
4.9
8.9
21
12
6. 1
10
12 hr
(% of
whole-body
burden)
5.4
16.0
9.1
5.7
2.8
0.4
0.5
2.3
0.9
0.9
6.4
0.6
1 1 .3
1.0
3.7
5.4
27.8
(ug/R
t issue)
21
60
26
534
35
28
29
11
38
19
29
18
4.')
10
22
IS
(. . 3
1!
24 hr
(% of
whole-body
burden)
5.0
13.4
9.2
13.8
1 . 9
0.5
0.4
0.7
4.9
0.8
7.4
0.6
8.5
0.8
3.2
'..4
23.3
Not detectable.
Source: Adapted I rom Kobnyash1 and Akllake, 1975/>, Table 1, p. 94. Reprinted by permi:
U>
O
U)
: i on of thr pul> I i slit11'
-------
TABLE D.5.16.
CHANGES IN RETENTION OF PENTACHLOROPHENOL IN GOLDFISH TISSUES DURING CULTURE IN RUNNING WATER
AFTER A 24-hr EXPOSURE TO A 0.2 mg/liter ['"C]PENTACHLOROPHENOL MEDIUM
Pentachlorophenol content
*P4 a 01 10
1 J.H oUc
Gills
Blood
Hepatopancreas
Gallbladder
Kidney
Spleen
Heart
Testis
Ovary
Air bladder
Digestive tract
Brain
Muscle
Vertebra
Skin
Scale
Remainder
Whole body
(ug/g
tissue)
19
42
23
461
44
18
28
10
9.0
16
52
18
4.8
11
23
15
6.9
13
1 hr
(% of
whole-body
burden)
4.6
10.0
9.4
9.5
2.2
0.4
0.4
1.4
2.1
0.9
13.8
0.6
8.6
0.8
3.4
5.5
26.5
(pg/g
tissue)
18
42
20
648
40
15
25
6.5
16
34
15
5.0
8.3
20
12
6.7
12
5 hr
(% of
whole-body
burden)
4.0
10.5
7.7
14.7
2.6
0.4
0.4
2.0
0.8
10.0
0.6
9.3
0.7
3.5
5.2
27.7
during excretion time of
(ug/g
tissue)
15
37
16
665
32
21
23
5.3
13
25
10
3.3
7.4
14
9.5
4.3
9.4
12 hr
(% of
whole-body
burden)
4.5
12.0
7.8
21.1
2.5
0.7
0.5
1.8
0.9
8.0
0.6
8.5
0.8
3.0
5.2
22.2
(ug/g
tissue)
13
34
13
1074
28
NDa
15
4.4
3.6
8.0
21
8.1
2.4
6.7
15
9.7
3.0
8.9
24 hr
(% of
whole-body
burden)
3.8
11.4
7.5
33.8
2.1
0.3
1.3
0.5
0.6
6.9
0.4
6.4
0.7
3.0
5.1
16.2
Not detectable.
Source: Adapted from Kobayashi' and Akitake, 1975b, Table 2, p. 95. Reprinted by permission of the publisher.
-------
305
accumulated levels of 35 mg/kg in the liver, 0.5 mg/kg in the muscle,
and 9 mg/kg in the digestive tract in 4 days. Fish were then placed in
clean water and much of the pentachlorophenol was rapidly eliminated.
After 16 days in clean water, residues were 0.6 mg/kg in the liver, 0.02
mg/kg in the muscle, and 0.13 mg/kg in the digestive tract; control fish
samples contained less than 0.01 mg/kg.
Thus, it is apparent that there are differences among fish species
in their abilities to concentrate pentachlorophenol; also, residue levels
vary for different tissues. In considering food consumption by humans,
pentachlorophenol levels are lower in muscle than in viscera.
D.5.2.1.3 Biotransformation — Kobayashi, Akitake, and Tomiyama
(1970a) found that the concentration of pentachlorophenol in seawater
decreased during the culture of short-necked clams (Tapes phi'lippinaPim).
Because this decrease in pentachlorophenol concentration was not accom-
panied by a quantitative increase in the pentachlorophenol content of
the shellfish, culture water was studied intensively to determine whether
pentachlorophenol was present in an altered form. This investigation
showed that the decrease in pentachlorophenol concentration in the medium
was not due to decomposition but rather to transformation to a bound form
of pentachlorophenol, which served as a detoxification mechanism in the
shellfish. The excreta of the shellfish and microorganisms in the medium
had no role in the formation of bound pentachlorophenol. Figure D.5.4
shows the time course of pentachlorophenol accumulation in the clam as
well as the accompanying buildup of bound pentachlorophenol in the cul-
ture medium. It can be seen that detoxification and excretion of penta-
chlorophenol are extremely rapid processes. Fifty hours following the
beginning of the culture period, more than 80% of the pentachlorophenol
found in the medium was in a detoxified, bound form.
The pentachlorophenol detoxification product was characterized by
Kobayashi, Akitake, and Tomiyama (19702?). Following culture of the
short-necked clam, they eluted the medium with ammonium acetone and
analyzed the eluate by silica-gel thin-layer chromatography. The isolated
conjugate displayed properties (with respect to chromatographic findings
and extractability with xylene) which were identical to those of synthe-
sized pentachlorophenol sulfate. The molar ratio of pentachlorophenol
to sulfate was about 1, which indicated that the isolated conjugate was
a sulfate ester of pentachlorophenol. These investigators concluded that
the shellfish detoxifies pentachlorophenol largely by formation of a sul-
fate conjugate.
When goldfish were cultured in freshwater containing pentachloro-
phenol, the pattern was very similar to that seen with the short-necked
clam (Akitake and Kobayashi, 1975). The amount of free pentachlorophenol
in the medium decreased without a quantitatively equal increase in penta-
chlorophenol in the fish tissue. The goldfish were exposed until they
accumulated 24.8 yg pentachlorophenol per gram body weight. The fish
were transferred to pentachlorophenol-free water, and the amounts of
pentachlorophenol (free and bound forms) in the fish and the water were
determined (Figure D.5.5). Pentachlorophenol was excreted from the fish
-------
306
ORNL-DWG 78-10514
O TOTAL PENTACHLOROPHENOL IN WATER
• SUM OF PENTACHLOROPHENOL IN SHELLFISH
AND TOTAL PENTACHLOROPHENOL IN WATER
A BOUND PENTACHLOROPHENOL IN WATER
• FREE PENTACHLOROPHENOL IN WATER
0 PENTACHLOROPHENOL ACCUMULATED IN SHELLFISH
20 30
TIME OF EXPOSURE ( hr)
Figure D.5.4. Change with time of culture in amounts of free and
bound pentachlorophenol in the medium and of pentachlorophenol in Tapes
philippinanm from the medium. Source: Adapted from Kobayashi, Akitake,
and Tomiyama, 1970a, Figure 3, p. 101. Reprinted by permission of the
publisher.
in a conjugated form, which was determined to be pentachlorophenol sul-
fate. This conjugate was identical to that found in the short-necked
clam by Kobayashi, Akitake, and Tomiyama (1970£>) . Apparently, the primary
route of pentachlorophenol elimination in at least two aquatic organisms
is conjugation to a sulfate. It is unknown how widespread this detoxifica-
tion method is because other studies of pentachlorophenol detoxification
in aquatic organisms did not identify degradation products.
Biodegradability and environmental fate of pentachlorophenol were
studied by Lu and Metcalf (1975) in a model aquatic ecosystem which in-
corporated a six-element food chain that included plankton, green fila-
mentous algae (Oedogonium cardiaeum), snails (fhysa sp.), water fleas
(Daphnia rnagna), mosquito larvae (Culex quinquifasoiatus), and mosquito
fish (.Garibusia affinis). The organisms were cultured in sealed 3-liter
flasks. On the first day of the experiment 300 daphnia, 200 mosquito
larvae, 6 snails, strands of algae, and miscellaneous plankton were
placed in flasks and acclimated in a programmed environmental growth
chamber for one day. Carbon-14-labeled pentachlorophenol was added to
-------
307
ORNL-DWG 78-10515
100
90
O TOTAL PENTACHLOROPHENOL IN WATER
A BOUND PENTACHLOROPHENOL IN WATER
• PENTACHLOROPHENOL IN FISH
• FREE PENTACHLOROPHENOL IN WATER
O
O
A
10
20 30 40
TIME OF EXCRETION (hr)
50
Figure D.5.5. Change in amounts of pentachlorophenol in goldfish
and in free and bound pentachlorophenol in pentachlorophenol-free water,
Source: Adapted from Akitake and Kobayashi, 1975, Figure 1, p. 324.
Reprinted by permission of the publisher.
the flasks at a concentration of 0.01 to 0.1 eg/liter. After 24 hr 100
daphnia and 50 mosquito larvae were removed from the flask and the I ^J
pentachlorophenol content was determined. Concomitantly, 3 fish were
added to the chambers. After 24 hr of incubation the experiment was
terminated, and samples were concentrated and analyzed by thin-layer
chromatography and autoradiography to identify pentachlorophenoi and
labeled metabolites (Table D.5.17). A biodegradability index, the ratio
of concentrations of polar products in a given organism to nonpolar prod
ucts in the same organism, was calculated for pentachlorophenol and 11
-------
308
TABLE D 5 17. DISTRIBUTION OF PENTACHLOROPHENOL AND DEGRADATION PRODUCTS
IN A MODEL AQUATIC ECOSYSTEM
Pentachlorophenol
Compound
Total lfcC
Unknown 1
Pentachlorophenol
Unknown 2
Unknown 3
Unknown 4
Unknown 5
Polar
Unextractable
¥
0.75
0.41
0.34
0.26
0.22
0.16
0.0
Culture
water
7.94
0.21
2.71
0.38
0.04
0.09
4.26
0.25
Alga
(Oedoaoninr,
cardiacim)
10.7
4.3
6.4
Daphnia
(Daphnia
magna)
1173
448
724
equivalent (ng/g)
Mosquito
(Culex
quinqui-
fasaiatus)
173
45.6
128
Snail
(Physa
sp.)
1138
329
27.2
33.2
163
586
Fish
(Gambusia.
3 f finis)
1076
804
272
Retardation factor determined by thin-layer chromatography in a solvent consisting of
n-hexane, acetone, acetic acid in ratio of 80:20:2 (v/v).
Source:
publisher.
Adapted from Lu and Metcalf, 1975, Table 9, p. 277. Reprinted by permission of the
other commonly used organic compounds. Values determined for the mos-
quito fish are given in Table D.5.18. Pentachlorophenol had relatively
high biodegradability indexes: snail, 1.06; alga, 1.48; daphnia, 1.61;
mosquito larvae, 2.80; and mosquito fish, 0.338. The relative detoxifi-
cation capacities of these organisms are shown in Figure D.5.6. The most
important means of pentachlorophenol degradation was conjugation at the
phenolic OH group. Conjugation of pentachlorophenol was a highly effi-
cient process in all organisms except the mosquito fish, which stored
large amounts of unmodified pentachlorophenol over the time span of the
experiment. Thus, the hazard to aquatic flora and fauna posed by penta-
chlorophenol appears to be intermediate among a series of commonly used
organic chemicals. A true assessment of the environmental significance
of pentachlorophenol in aquatic communities awaits further investigation.
D.5.2.1.4 Elimination — Kobayashi and Akitake (1975a) studied the
kinetics of pentachlorophenol excretion in the goldfish. When goldfish
were exposed to 0.1 and 0.2 mg/liter pentachlorophenol in the media for
24 hr (reaching mean tissue concentrations of 23.5 and 41.6 ug penta-
chlorophenol per gram body weight respectively) and were then trans-
ferred to running water, concentrations of pentachlorophenol in the fish
decreased as shown in Figure D.5.7. At least two rates apparently apply
to excretion of pentachlorophenol by goldfish. Excretion was initially
rapid, resulting in pentachlorophenol concentrations in the fish of 20%
of initial values after 20 hr. Subsequent decreases were much slower.
After 100 hr, 5% of the original pentachlorophenol content was still
present in the fish. Exposure time had no effect on the retention of
pentachlorophenol in fish (Figure D.5.8). Fish were exposed to 0.2
mg/liter pentachlorophenol for 6, 12, 24, and 48 hr. After fish were
transferred to running water, the retention curves showed similar
-------
309
TABLE D.5.18. BIODEGRADABILITY INDEXES OF
ORGANIC CHEMICALS DETERMINED FOR MOSQUITO
FISH IN A MODEL AQUATIC ECOSYSTEM
Compound Biodegradability
Aldrin 0.015
Aniline 1.784
Anisole 0.250
Benzoic acid 2.965
Chlorobenzene 0.014
DDT 0.012
2,6-Diethylaniline 0.139
Hexachlorobenzene 0.377
Nitrobenzene 0.023
Pentachlorophenol 0.338
Phthalic anhydride 11.884
3,5,6-Trichloro-2-pyridinol 0.311
Ratio of concentrations of polar products
to nonpolar products in the mosquito fish.
Source: Adapted from Lu and Metcalf,
1975, Table 1, p. 270. Reprinted by permission
of the publisher.
patterns. Again, a relatively rapid initial rate of excretion was
followed by a much slower rate.
The studies of Kobayashi and Akitake (1975a), like the investiga-
tions of Holmberg et al. (1972) (Section D.5.2.1.2), can lead to false
conclusions because of deficiencies in methodologies. Neither of these
studies was designed to provide reliable information on long-term residue
kinetics. Kobayashi and Akitake (1975a) found a concentration factor of
1000-fold for a 120-hr exposure. The water was not analyzed for penta-
chlorophenol, and control fish were not placed in the untreated water
and analyzed for pentachlorophenol residues. A few micrograms per liter
of pentachlorophenol in the untreated water would contribute to the
tissue levels observed at the end of the 100-hr elimination phase.
In the short-necked clam, pentachlorophenol is probably excreted
through the bojanus1 organ (Kobayashi, Akitake, and Tomiyama, 1969),
although this assumption has not been tested rigorously. Tissue distri-
bution studies by Kobayashi and Akitake (1975ft) suggest that the hepato-
pancreas and gallbladder play important roles in the excretion of
pentachlorophenol from the goldfish. Pentachlorophenol taken up by the
fish is likely transferred to the hepatopancreas, detoxified, and partly
transferred to the gallbladder and bile. The slow excretion kinetics
-------
310
ORNL-DWG 78-10516
80
70 -
60 -
50 -
Q
LJ
(E
LU
O 40
O
UJ
cc
o
30 -
20 -
10 —
0
|!
: PENTACHLOROPHENOL
%
„
—
??
ENTACHLOROPHENOL
ONJUGATE
1
1
—
\
OEDOGON1UM DAPHNIA CULEX
PHYSA GAMBUSIO
Figure D.5.6. Relative detoxification capacities of key organisms
in a model aquatic ecosystem following treatment with radioactive penta-
chlorophenol. Source: Adapted from Lu and Metcalf, 1975, Figure 9, p.
279. Reprinted by permission of the publisher.
-------
ORNL-DWG 78 — 10517
40
- 30
v>
• 0.2 mg/llter
O 0.1 mg/liter
40 60
TIME (hr)
80
100
ORNL-DWG 78-10516
O 48-hr EXPOSURE
• 24-hr EXPOSURE
A (2-hr EXPOSURE
• 6-hr EXPOSURE
10 15
TIME (hr)
Figure D.5.7. Retention of pentachlorophenol
in goldfish during culture in running water after
a 24-hr exposure to pentachlorophenol media (0.1
and 0.2 mg/liter). Source: Adapted from
Kobayashi and Akitake, 1975a, Figure 2, p. 90.
Reprinted by permission of the publisher.
Figure D.5.8. Retention of pentachlorophenol
in goldfish during culture in running water after
various exposures (6 to 48 hr) to 0.2 mg/liter
pentachlorophenol. Source: Adapted from
Kobayashi and Akitake, 1975a, Figure 3, p. 90.
Reprinted by permission of the publisher.
-------
312
noted in the goldfish after the pentachlorophenol content reached 20%
of the initial value may have resulted from storage of pentachlorophenol
in the gallbladder. Other investigators have suggested that the gall-
bladder has an important role in the excretion of pentachlorophenol in
mammals (Jakobsen and Yllner, 1971). Pentachlorophenol may also be
stored in lipids, which have been suggested as a source of pentachloro-
phenol redistribution (Holmberg et al., 1972).
D.5.2.2 Effects
D.5.2.2.1 Physiological and Biochemical Role — There is no evi-
dence that pentachlorophenol has a necessary metabolic role in aquatic
organisms; thus, its presence in organisms must result from environmental
contamination.
D.5.2.2.2 Toxicity
D.5.2.2.2.1 Mechanism of action — The biochemical mechanism of
pentachlorophenol toxicity to aquatic organisms likely involves its
ability to uncouple oxidative phosphorylation and at higher concentra-
tions to inactivate glycolytic enzymes. These effects, as they relate
to human toxicity, are discussed in Section D.6.2.2.1. The mechanism
of pentachlorophenol toxicity to mammals probably also applies to aquatic
organisms, but no direct data on this subject are available.
D.5.2.2.2.2 Local and systemic pathology — No information on local
or systemic pathology in aquatic organisms was found.
D.5.2.2.2.3 Acute toxicity — Pentachlorophenol and sodium penta-
chlorophenate are extremely toxic to aquatic organisms when substantial
amounts reach the receiving water. Numerous fish kills have resulted
from seepage of pentachlorophenol-contaminated effluents or from spillage
of the concentrated compound into waterways. The use of pentachlorophenol
(or sodium pentachlorophenate) as a herbicide also has caused death of
aquatic organisms. Shim and Self (1973) reported that the use of sodium
pentachlorophenate as a herbicide in Korean rice fields caused 100% mor-
tality of larvivorous fish. The 100% mortality occurred at dosages as
little as 10% of concentrations prevalently used for herbicidal purposes.
Significant damage to soft clams in tidelands around the Aniake Bay of
Japan was observed by Nitta (1972). Widespread death of fish occurred
in Lake Biwa, Japan, following a heavy rain immediately after herbicidal
application of pentachlorophenol to paddy fields around the Chikugo River.
The susceptibility of different fish species to pentachlorophenol
toxicity varies. Of 19 species of fish studied by Goodnight (1942), the
most sensitive species were unable to survive at pentachlorophenol levels
greater than 0.2 mg/liter; more tolerant species survived at 0.4 to 0.6
mg/liter. However, aquatic invertebrates are more tolerant than fish to
the effects of pentachlorophenol and are able to survive at concentra-
tions which kill many species of fish. Acute toxic responses of fish
and aquatic invertebrates to pentachlorophenol are compiled in Table
D.5.19. Minimum lethal concentrations of sodium pentachlorophenate for
-------
TABLE D.5.19. ACUTE TOXICITY OF PENTACHLOROPHENOL TO AQUATIC ORGANISMS
Species
Time
(hr)
Pentachlorophenol
concentration
(ug/liter)
Source
Levels causing 50% lethality
Bluegill (Leporrria maarochirus)
Guppy (Poeailia retiaulata)
Guppy (Lebiatea retioulatua)
Fish (Aplooheilua latipea)
Fish (Zacco platypua)
"Guchi" fish (Nibea albiflora)
"Warasubo" fish (Odontamblyopua mbiaundua)
Eel (Anguilla japonica)
Rainbow trout (Salmo gairdneri)
Coho salmon (OncorhynohuB kieutah)
Sockeye salmon (Onoorhynahus nerka)
Underyearling
Fathead minnow (Pimephales promelaa)
Goldfish (Caraaaiua es philippiniiifum)
Tub!fex worms (Tubifex kubi.j'cx and
Linrnodrilua hoffmc.ietcr!)
"Sliiraebi" shrimp (Leundei1 japonii-uo)
Mosquito larvae (Culex kr'tk(trnior>hijn<-huc,)
White crappie (Pomaxis annulut'in)
Stuelliead trout (!j(iltno /jai.rdncr'i.)
Embryos
Alevins
Oystor C'gj.;s and larvae (.Ci'aaiionl.i'i'ii
I.'/I";/'''"'<-'•')
Clam eggs and larvae (Venues nici',-cu~i)'Lr.>')
Shell fish (VaiiairupLn phi-1 i.pj'ii.nai'iuii)
48
24
96
6
24
24
48
48
24
96
96
24
96
96
96
96
1.2
96
48
96
120
24
48
24
29-39
350
250
4,000
140
230
80
250
200
47-110
32-93
150
50-130
63
210-340
210
200
49-56
460
60
200
310-1,400
2,300
20,900
f.5-751'
Levels causing 100% lethality
50
200
250
250
100
Inglis and Davis, 1973
Turnbull, DeMann, and Weston, 1954
Anderson and Weber, 1975
Klock, 1956
Shim and Self, 1973
Shim and Self, 1973
Tomiyama and Kawabe, 1962
Tomiyama and Kawabe, 1962
Tomiyama and Kawabe, 1962
Davis and Hoos, 1975
Davis and Hoos, 1975
Ilanes et a I . , 1968
Davis and Hoos, 1975
Webb and Brett, 1973
Ruesink and Smith, 1975
Adelman, Smith, and Siesennop, 1976
Kobayashi and Akitake, 1975a
Inglis anil Davis, 1973
Clemens and Sneed, 1959
Cote", 1972
Kobayashi, Kurokawa, and Tomiyama, 19d9/>
Whit ley, I9h7
Tomiyama and Kawabe, 1 2
Shim and Self, 1973
Springer, 19r>7
Chapman, I'M) 9
Chapman, ]<)d9
Davis, I9«)l
Davis, 19(>I.
Tom 1 vania et al., 11M)_!
UJ
H1
CO
-------
TABLE D.5.19 (continued)
Species
Time
Pentachlorophenol
concentration
(ug/1-lter)
Source
Levels
Shellfish (Conchoceli.8 sp.)
Crayfish (Cambarua vivilia)
Amphipod (Hyalella kniakerbockeiri)
Cladocera (Daphnia pulex)
Dragonfly nymphs (Epiaordulia sp.)
Damsel fly nymphs (lechnwra sp.)
Isopod (Asellua cormunis)
producing
Levels ranging between 100%
Silver-mouthed minnow (Eriaymba buccata)
Blackfin minnow (Notropis urribratilis)
Doughbelly (Campostoma anomalwn)
Steel-colored minnow (Notropis whipplii)
Blunt-nosed minnow (Pimephales notatus)
Horned dace (Semotilus atromaculatus)
Orange-spotted sunfish (Lepomis hwnilie)
Top minnow (Fundulus notatus)
Tadpole (Rana pipiens)
6.3
4.3
5.3
7.5
6.3
6.8
9.8
9.5
no toxic effect
800
9,500
5,000
5,000
5,000
5,000
5,000
5,000
survival and 100%
200-400
400-600
200-400
200-400
200-400
400-600
200-400
600-800
600-800
Tom 1 yama ,
Spr Inger ,
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
lethal! ty
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
Goodnight
Kobayashi, and Kawabe, 1962a
1957
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
, 1942
U)
lethal concentration.
-------
315
fish and aquatic invertebrates as reported by Norup (1972) are shown in
Figure D.5.9. This graph illustrates two points: (1) a considerable
range of minimum lethal concentrations exists for various species of
fish, and (2) although some studies have reported that invertebrates are
more tolerant than fish to sodium pentachlorophenate, many invertebrates
apparently tend to be just as sensitive.
Chapman (1969) found that sodium pentachlorophenate was lethal to
trout alevins at a concentration of 70 yg/liter and to embryos at 50
yg/liter. Additionally, 40 yg/liter was invariably lethal if the embryo
and alevin stages were exposed to sodium pentachlorophenate. Growth of
the alevin was reduced by approximately 6% for each 10 yg/liter incre-
ment. Reduced growth rates, reduced efficiency of yolk utilization, and
increased rates of yolk metabolism and oxygen consumption were evident.
Thus, relatively low concentrations of sodium pentachlorophenate caused
adverse effects.
ORNL-DWG 78-10519
4
103
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in
101
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x\x I
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INVERTEBRATES
! I I
0.1 1
SODIUM PENTACHLOROPHENATE CONCENTRATION
(mg/liter)
Figure D.5.9. Boundary of lethal area for a variety of fish species,
relating lethal concentration of sodium pentachlorophenate to time of
survival. The lethal concentrations for invertebrates are similar to
those for fish. Source: Adapted from Norup, 1972, Figure 1, p. 1586.
Reprinted by permission of the publisher.
-------
316
Danil'chenko and Stroganov (1975) studied the effect of sodium
pentachlorophenate on the embryonic and early postembryonic development
of freshwater fish. Fertilized fish eggs were cultured in Moscow river
water containing pentachlorophenol. The number of embryo deaths and
developmental abnormalities were noted for pike (Esox lucius), perch
(Perca fluviatilis), ruffe (Acerina cemua), roach (Rutilus rutilus),
minnow \Phoxinus phoxinus), gudgeon (Gobio gobio'), loach (Misgurnus
fossilis), and spiny loach (Cobitis taenia). Death of embryos and mor-
phological disturbances, such as dropsy of the pericardium, elongation
of the heart chambers, and absence or retardation of inflation of the
swim bladder, were seen in all species tested when the sodium penta-
chlorophenate concentration in the culture medium was greater than 0.5
mg/liter. The effect of sodium pentachlorophenate on embryonic develop-
ment depended on the species. The most resistant species were pike,
perch, and ruffe; embryos of the spiny loach, minnow, and roach were the
least resistant. The specific kinds of morphological alterations also
varied among the species. At 1 mg/liter sodium pentachlorophenate
development ceased following overgrowth of the vitellus of the blastoderm
in the perch, ruffe, pike, and loach. Development was arrested at the
morula stage in the minnow and the spiny loach. There were no morpho-
logical disturbances or deaths when fish eggs were cultured in media
containing 0.1 mg/liter pentachlorophenol. These investigators concluded
that the maximum permissible concentration of sodium pentachlorophenate
in water should be 0.1 mg/liter. Small but significant deviations from
the control, such as length of prolarvae and larvae, time of hatching,
and heart rate, were noted in fish embryos cultured at lower concentra-
tions of pentachlorophenol (0.01 and 0.001 mg/liter). Further study is
needed to verify these findings and to determine the mechanism of toxic
action.
In an effort to control schistosomiasis, a severe endemic disease
of humans in much of Asia, Africa, and South America, sodium pentachloro-
phenate has been used to destroy Australorbis glabratus, the snail which
serves as intermediate host for schistosomes. This compound is extremely
effective and is probably the most widely used molluscicide. At a con-
centration of 10 mg/liter, sodium pentachlorophenate was lethal to 90%
to 100% of the snails (Berry, Nolan, and Gonzalez, 1950). Adult snails
placed in sodium pentachlorophenate solutions containing 0.05 and 0.1
mg/liter for seven to eight days generally showed reduced egg production.
Removal of the chemical from the snails' environment resulted in egg pro-
duction and improved egg viability (Olivier and Raskins, 1960). Yasuraoka
and Hosaka (1971) tested the toxicity of sodium pentachlorophenate to the
snail Oncomelan-ia nosophora. Snails collected from villages in the
Yamanashi area of Japan were tested yearly for susceptibility to sodium
pentachlorophenate toxicity. The LCSO values over a ten-year period
ranged from 0.25 to 0.37 mg/liter.
Shiff and Garnett (1961) studied the effect of molluscicidal con-
centrations of pentachlorophenol on the microflora and microfauna of
small, biologically stable fish ponds in Southern Rhodesia. The aquatic
organisms present included Cladocera, aquatic insect larvae, Copepoda,
Copepod naupUi, Ostracoda, and Spirogyra sp. Ponds (4 by 4 m) were
-------
317
treated with sodium pentachlorophenate until the level reached 5 mg/liter.
Total numbers of microflora and microfauna and fluctuations among groups
of microflora and microfauna in the pond were determined. A dramatic
reduction in all forms of planktonic life was seen immediately after
sodium pentachlorophenate was added. The effect, however, was generally
short-lived; 32 days after application population trends returned to
normal.
Tagatz et al. (1977) studied the effects of pentachlorophenol on
estuarine organisms during a nine-week exposure. Populations of mollusks
decreased at pentachlorophenol levels of 7 yg/liter, and the number of
annelids and arthropods decreased at 76 yg/liter. Almost no animals
survived at 622 yg/liter. Pentachlorophenol was not found in the aquaria
sediment in the 7 yg/liter tank. In the 76 and 622 yg/liter tanks, 0.7
to 9 yg/kg pentachlorophenol was recovered from the sediment.
The eight-day LC50 for crayfish (Astacus fluviatilis*) exposed to
pentachlorophenol was determined by Kaila and Saarikoski (1977). At
pH 7.5 the LC5o was 53 mg/liter, and at pH 6.5 it was 9.0 mg/liter.
D.5.2.2.2.4 Chronic toxicity — The lethal concentrations in Table
D.5.19 are a poor indication of the true environmental significance of
pentachlorophenol. Dramatic effects such as massive fish kills are
readily seen and are aesthetically objectionable; however, other more
subtle effects may occur in aquatic communities exposed to pentachloro-
phenol residues. This exposure may decrease the ability of some species
to reproduce, thereby affecting the survival of a species or even the
survival and integrity of entire biological communities. The chronic
effects of pentachlorophenol on aquatic organisms are summarized in
Table D.5.20. Decreased growth and a curtailment of food conversion
efficiency have been reported. Serious effects such as renal degenera-
tion, liver damage, and retarded gonadal development were found by
Crandall and Goodnight (1963).
The metabolic effects of pentachlorophenol on the eel (Anguilla
anguilla L.) have been examined by Holmberg et al. (1972). Eels were
exposed to 0.1 mg/liter pentachlorophenol in seawater and freshwater.
In the seawater tests, the eels were exposed for 8 days to pentachloro-
phenol-containing seawater followed by 8 days in pentachlorophenol-free
water. The freshwater tests involved exposure to pentachlorophenol-
containing water for 4 days followed by a recovery period of 55 days.
The effects of these exposures on a large number of metabolic parameters
are shown in Tables D.5.21 and D.5.22. The notable effects are summa-
rized in Table D.5.23. The pentachlorophenol-treated eels did not fully
recover despite spending two months in clean water. A schematic diagram
of the action of pentachlorophenol on eels was prepared by Larsson (1973)
and is presented as Figure D.5.10.
Bostrom and Johansson (1972) studied the effect of sublethal con-
centrations of pentachlorophenol on liver enzymes such as hexokinase,
glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase,
pyruvate kinase, lactate dehydrogenase, fumarase, and cytochrome oxidase
-------
TABl.Ii D.5.20. CHRONIC KKFKCTS Ol' I'KNTACMUMOI'IIKNOI, ON AQUATIC OKCANISMS
Spcclc.H
Time
(days)
J'enta-
chlorophenol
concentration
dig/liter)
Expcr Lmi'iil a I
conel I t Ions
Source
Coho salmon (Oni;oi'h>/>h-hua kiauh^h)
Guppy (Lebiates r'ctiauiatua)
100
Cichlld fish
Tubifex worms (Tubifex tiibifcx
and Limnodrilua hoffmeiateri)
Underyearling sockeye salmon
(Onoorhynahue nerka)
Pike (Eeox Indus), perch (Peraa
flitviatilia), ruffe (Aaerina
aetmua), roach (Rutilia rutilia),
minnow (Phoxinua phoxinua),
gudgeon (Gobio gobio), loach
(Miagurnua foBailia), and spiney
loach (Cobitia taenio)
Shellfish (Venerupi-a philippinarum)
180
500
10
200
14-56
100-1250
0-50
1-5000
100
I'o Lass Ltim pcnL.'ifh 1 oropli
11 "C with 12-hr ilurk
I It-ht porlocls In filL
nprliu'. water
Sod I um piMitac'lilorophuiiale ;
total hardness 165 mf>/
liter; total alkalinity 99
mg/llter; dissolved oxygt'M
8.5 mK/literj 12-hr dark
and light periods; pll B./t
to 8.6
Potassium pcnlriclilordplit'iiate;
25"C
Sodium pentachlorophc'iiate;
Knopps solution 0.01% at
pH 9.5
Sodium pentachlorophenate;
dissolved oxygen at 9% to
100% saturation; pH 6.8;
16-lir photopyrlod
Sodium pentachlorophenate;
Moscow river water; embryo
development monitored
Seawater
1'ally acid catabolism at Manes et al., \<1(,H
1*17, of available acids
(25% for controls) ;
catabolIsm proportfonal
to available mass1 of
Individual fatly acids
Crowth Inhibition; lack of (,'raudal.l and
mesenterlc fat; dilation (,'oodnlght , 196'!
of renal tubules wilh
degeneration of tubular
epithelial cells; re-
tarded gonadal develop-
ment; liver damage
Increased caloric loss dur- Krueger et a 1.. , \1>M
Ing starvation; increased
food Intake and energy
losses; decreased growth;
caJoric cost of exercise
Increased relative to
controls
Increasing resplrat Ion rate Whltley and Slkora,
(expressed as oxygon con- l'J70
sumed per mllligam per
hour) with increasing sodi-
um pentachlorophenate levels
oo
Decreased growth (threshold
concentration » 1.74 ug/
liter); decreased food con-
version (threshold concen-
tration = l.fi ug/liter);
no effect on swimming
performance
Severe developmental abnor-
malities in all species
at concentrations >1
mg/llter
Webh and Brett, 1973
Dan 11 'chenko. and
Stroganov, 1975
Appreciable decrease In "P Tomiyama, Kobayashi,
uptake by the shellfish and Kawabe,
relative to control animals
-------
TABLE D.5.21. METABOLIC EFFECTS OF PENTACHLOROPHENOL (0.1 nig/liter) ON EELS IN FRESHWATER
Parameter
Decrease in body weight, %
Hematocrit, %
Hemoglobin, mg/100 ml
Plasma chloride, mW
Plasma inorganic phosphate,
mg/100 ml
Total plasma protein, g/100 ml
Total plasma cholesterol,
mg/100 ml
Esterified plasma cholesterol,
mg/100 ml
Free plasma cholesterol,
mg/100 ml
Plasma triglycerides, mM
Plasma free fatty acids, \iM
Blood glucose, mg/100 ml
Blood lactate, mg/100 ml
Liver-somatic index, (liver
wt x 100) /body wt
Liver trlglyceride.s , mg/100
mg wet wt
Muscle triglycerides, mg/100
mg wet wt
Muscle glycogen, mg/100 mg
wet wt
4-day exposure
Control^
2.4 ±
28.3 ±
9.2 +
114 i
7.0 ±
5.1 <
252 ±
166 i
86 i'.
3.5 '
459 '
53.8 i
1.1.5 i
1.2 '
5.1 i
9.1 '
0.13 '
1.0
1.5
0.3
3
0.7
0.4
23
12
14
0.7
43
6.7
2.2
0.1
1.4
1.3
0.01
Treated
6.0 ±
37.7 ±
11.1 ±
111 ±
10.13 ±
5.2 ±
339 i
225 '
111 *
4.0 '
517 '
152 •'
16.7 i
1 .23 i
4.3 ..-
6.5 f:
0.13 L
1.3C
2.3rf
0.4^
1
0.2
16"
j
10J
14
0.9
33
18''
2.8
0.08
0.8
1.1
0.01
4-day exposure +
4-day recovery
Control12
3.9 '
31.0 *
10.1 *
113 i
6.9 i
5.3 t
270 •>
174 +
99 i
4.1 :':
437 +
68 :'•
7.1 i
1.3 i
3.4 •:
7.1 ±
0.14 i
0.8
1.6
0.4
3
0.6
0.2
18
13
7
0.7
34
15
0.6
0.06
1.7
0.4
0.02
Treated
7.9
37.5
10.6
103
7.0
5.1
304
195
109
4.8
513
124
6.9
1.26
3.2
5.5
0.12
± 1.5<*
± 0.7d
i 0.5
. 4
± 0.3
+ 0.2
»- 17
' 13
i 12
.'1.5
i 37
: 20. I''
> 1.3
i 0.08
'1.3
-'. 0.7
' 0.03
4-day exposure +
55-day recovery
Treated^
16.2
35.7
9.4
96
5.4
5.2
306
201
105
4.5
552
109
12.3
1.51
3.1
4.9
0.24
i 1.8
i 1.8
+ 0.6
i 4
± 0.3
+ 0.3
' 22
.'• 19
U)
I-1
9
± 0.6
•<- 42
... 29
J 1.6
t 0.05
.'1.2
! 0 . h
> 0.02
rEight eels Jn group,
._Nlne eels in group.
'./' < 0.05.
/' < 0.005.
Source: Adapted from HolmhcrR et al., 1972, T;ihle 3, p. 180. Reprinted by permission of (lie publisher.
-------
320
TABLE D.5.22. METABOLIC EFFECTS OF PENTACHLOROPHENOL (0.1 rag/liter) ON EELS IN SEAWATER
8-day exposure
Parameter
Decrease in body weight, %
Hematocrit, %
Hemoglobin, mg/100 ml
Plasma chloride, m.V
Plasma inorganic phosphate,
mg/100 ml
Total plasma protein, g/100 ml
Total plasma cholesterol, mg/100 ml
Esterified plasma cholesterol,
mg/100 ml
Free plasma cholesterol, mg/100 ml
Plasma triglycerides, wM
Plasma free fatty acids, yW
Blood glucose, mg/100 ml
Blood lactate, mg/100 ml
Liver-somatic index, (liver wt x
100) /body wt
Liver triglycerides, mg/100 mg
wet wt
Muscle triglycerides, mg/100 mg
wet wt
Liver glycogen, mg/100 mg wet wt
Muscle glycogen, mg/100 mg wet wt
Liver glutamate pyruvate trans-
aminase, milliunit/mg wet wt
Muscle glutamate pyruvate trans-
aminase, milliunit/mg wet wt
Control
1.3 ± 0.5
38.4 ± 0.5
10.5 ± 0.5
141 ± 5
7.2 ± 0.4
4.0 ± 0.1
373 ± 40
227 ± 23
147 ± 27
3.6 ± 0.9
399 ± 16
45.1 ± 2.7
7.5 ± 0.8
1.29 ± 0.09
6.0 ± 1.5
11.3 ± 2.4
3.2 ± 0.5
0.16 ± 0.01
30.7 ± 7.6
0.65 ± 0.12
Treated
1.7 ± 0.6
41.1 ± 0.8°
12.3 ± 0.5°
141 ± 3
8.3 ± 0.3
4.5 ± O.ld
378 ± 39
253 ± 19
125 ± 23
6.2 i 0.8°
424 ± 17
116.3 ± 5.5d
12.0 ± l.ld
1.25 - 0.11
4.2 ± 1.5
8.2 ± 1.7
2.5 ± 0.4
0.11 ± 0.02C
27.3 i 4.3
0.47 ± 0.07
8-day exposure +
8-day recovery
Control0
2.2 ± 0.7
35.3 ± 0.4
10.0 ± 0.3
144 ± 2
7.0 ± 0.2
4.4 ± 0.2
336 ± 22
234 ± 19
101 ± 15
3.7 ± 0.4
369 ± 13
40.4 ± 2.1
7.4 ± 1.1
1.21 ± 0.04
5.4 ± 1.9
9.0 ± 2.1
3.3 ± 0.3
0.11 ± 0.02
42.6 ± 6.9
0.59 ± 0.07
Treated
6.2 ± 0.8^
38.3 ± 0.3d
11.6 ± 0.4d
145 ± 1
7.1 ± 0.2
4.6 ± 0.2
433 ± 31C
260 ± 24
172 ± lld
5.0 ± 0.7
565 ± 51d
85.7 ± 2.9^
12.1 ± 1.3°
1.44 ± 0.08
5.3 ± 1.5
6.6 ± 1.4
2.6 ± 0.6
0.14 ± 0.03
24.9 ± 3.1°
0.39 ± 0.04C
-Eight eels in group.
Nine eels in group.
';? < 0.05.
"P < 0.005.
Source: Adapted from Holmberg et al., 1972, Table 4, p. 181. Reprinted by permission of the
publisher.
which are involved in energy metabolism in the eel. Eels were maintained
in freshwater containing 0.1 mg/liter sodium pentachlorophenate for 4
days. Following treatment, the eels recovered for 30 days in penta-
chlorophenol-free freshwater. Activities of pyruvate kinase and lactate
dehydrogenase decreased after pentachlorophenol treatment, but activities
of hexokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate
dehydrogenase, fumarase, and cytochrome oxidase increased. Following
the 30-day recovery period, enzyme activities approximated those of
-------
321
TABLE D.5.23. EFFECTS OF PENTACHLOROPHENOL ON THE EEL
Parameter
Effect
Hematocrit
Hemoglobin
Inorganic phosphate
Blood glucose
Blood lactate
Plasma triglycerides
Plasma free fatty acids
Plasma esterified cholesterol
Plasma free cholesterol
Liver-somatic index
Liver glycogen
Liver glutamate pyruvate transaminase
Muscle glutamate pyruvate transaminase
Rapid and persisting increase
Rapid and persisting increase
Initial increase
Rapid and persisting increase
Rapid increase
Increase
Slow increase
Slight increase
Slight increase
Slight increase
Slight initial decrease
Decrease
Decrease
Source: Adapted from Larsson, 1973, Figure 2, p. 623.
Reprinted by permission of the publisher.
ORNL-DWG 78-10520
HYPERMETABOLIC
STATE
UNCOUPLING
EFFECT
PENTACHLOROPHENOL
DISTURBED LIVER
FUNCTION
CLINICAL INFORMATION
INCREASED UTILIZATION OF TISSUE
ENERGY RESERVES.
A. LIVER AND MUSCLE FAT MOBILIZA-
TION. INCREASED LEVELS OF BLOOD
LIPIDS (FREE FATTY ACIDS.
TRIGLYCERIDES. CHOLESTEROLI
B. INCREASED GLYCOGENOLYSIS IN
LIVER AND MUSCLE, INCREASED
LEVELS OF BLOOD GLUCOSE AND
BLOOD LACTATE
INCREASED RESPIRATION:
A. INCREASED RESPIRATORY MOVEMENTS
B. POLYCYTHEMIA
III. ENLARGEMENT OF THE LIVER
ALTERED CHOLESTEROL METABOLISM
DECREASED LIVER GPT ACTIVITY
Figure D.5.10. Action of pentachlorophenol on eels in vivo. Source:
Adapted from Larsson, 1973, Figure 3, p. 624. Reprinted by permission
of the publisher.
-------
control animals.
enzymes.
322
In in vitro tests, pentachlorophenol inhibited all
These reports by Holmberg et al. (1972) and Bostrom and Johansson
(1972) indicate that the effects of pentachlorophenol at the molecular
level may persist following single sublethal exposures. Pentachloro-
phenol remained above background levels in the eels for the duration of
the experiment, and these low levels of pentachlorophenol in the tissues
may exert long-term toxic effects. Additional research to determine
whether enzyme systems are permanently damaged is needed.
D.5.2.2.2.5 Effect of environmental parameters on toxicity — The
toxicity values in Table D.5.19 as well as those reported elsewhere
should be considered estimates. In a bioassay standardization study by
Davis and Hoos (1975), seven government and private laboratories in
British Columbia were provided identical reference toxicants and compre-
hensive guidelines to be used in conducting the bioassays. Data obtained
are shown in Table D.5.24. The results, expressed as 96-hr LC50 values,
varied as much as threefold among laboratories. Thus, even when experi-
mental conditions and the toxicant are rigidly standardized, large varia-
tions among investigators are frequently encountered. When different
laboratories using different techniques and sources of toxicant perform
similar experiments, data variability may be much greater than threefold.
Water conditions such as temperature, pH, and salinity may affect
the toxicity of pentachlorophenol to aquatic organisms, either directly
TABLE D.5.24. SUMMARY OF RESULTS REPORTED BY SEVEN LABORATORIES USING
SODIUM PENTACHLOROPHENATE AS A REFERENCE TOXICANT FOR SALMONID BIOASSAYS
Species
Rainbow trout (Salmo gairdneri)
Coho salmon (Onaorhynchus kisutah)
Sockeye salmon (Oncorhynchus nerka)
Laboratory
code
A
B
C
D
E
F
C
E
D
G
LC50
Log-probit
estimate
48
100
50
96
92
75
37
96
50
130
(yg/liter)
Nomographic
calculation12
47 (32.9, 67.2)
106 (88.5, 127.0)
50 (29.8, 84.0)
96 (90.1, 102.2)
98 (87.5, 109.8)
b
31.8 (24.9, 40.6)
92 (79.3, 106.7)
50 (40.3, 62.0)
130 (119, 142)
fc95% confidence limits; upper and lower limits in parentheses.
Insufficient data for calculation of confidence limits.
Source: Adapted from Davis and Hoos, 1975, Table 2, p. 414. Reprinted by per-
mission of the publisher.
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323
by changing the metabolic rate of the organisms or indirectly by alter-
ing the biological availability of pentachlorophenol. Goodnight (1942)
reported that temperature - in the range of 9°C to 24°C - did not mark-
edly influence the toxicity of sodium pentachlorophenate to fish. At
higher temperatures — 28°C to 30°C - fish succumbed more rapidly to
sodium pentachlorophenate poisoning, but this higher fatality rate was
ascribed to the high temperature per se and the resulting depleted oxygen
content of the water. A pronounced effect of pH on the toxicity of
sodium pentachlorophenate was noted by Goodnight (1942). The pH of the
medium varied from 5 to 8; fish survived longer in pentachlorophenol-
contaminated water at pH 7.6 than at pH 6.6 or less. The increased
survival time, especially at low concentrations of sodium pentachloro-
phenate (<0.4 mg/liter), was several hours. Above the subsistence level
of dissolved oxygen content (2 mg/liter for most fish), variation in
oxygen content of the water did not affect the survival time of fish.
Ruesink and Smith (1975) determined the 96-hr LC50 for fathead minnows
exposed to sodium pentachlorophenate at 15°C and 25°C and found increased
toxicity at the higher temperature (Table D.5.25).
TABLE D.5.25. THE 48- AND 96-hr LCSO VALUES AND THE
LETHAL THRESHOLD CONCENTRATION OF SODIUM
PENTACHLOROPHENATE FOR FATHEAD MINNOWS AT 15°C AND 25°C
Lethal
Temperature 48-hr LC50 96-hr LC50 threshold
(°C) (mg/liter) (mg/liter) concentration
(mg/liter)
15
25
0.21
0.37
0.21
0.34
0.21
0.33
Source: Adapted from Ruesink and Smith, 1975,
Table 2, p. 569. Reprinted by permission of the
publisher.
Studies of the acute toxicity of pentachlorophenol to fish at dif-
ferent water hardnesses (13 to 365 mg/liter) showed that hardness had
little or no effect on toxicity to bluegill (Lepomis macrochirus'), rain-
bow trout (Salmo gairdneri') , bluespotted sunfish (Lepomis sp.), goldfish
(Carassius awcatus), redear sunfish (Lepomis sp.), and black bullhead
(.Ictalwcus sp.) (Inglis and Davis, 1973). Determination of the effect
of pH on the toxicity of sodium pentachlorophenate to tubifex worms
showed TL^ values of 0.31, 0.67, and 1.4 mg/liter at pH 7.5, 8.6, and
9.5 respectively. This significant effect confirms the findings with
other aquatic animals showing that a decrease in pH enhances the toxic
effect of sodium pentachlorophenate.
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324
Alderdice (1963) studied the median resistance times of juvenile
coho salmon (Oncorhynclws kisutcK) to 3 mg/liter sodium pentachlorophenate
at different combinations of salinity, temperature, and dissolved oxygen
content. Each parameter affected the toxicity of sodium pentachloro-
phenate. Coho salmon demonstrated maximum resistance to sodium penta-
chlorophenate at 17.68 g/liter salinity, 4.86°C, and 7.66 mg/liter oxygen.
When the hazards associated with the presence of a toxic substance
in the environment are assessed, it is important to consider the possible
effects of other pollutants, either natural or man-made, on the toxicity
of the compound. For example, Statham and Lech (1975) found that ex-
posure of rainbow trout to a nonlethal concentration of carbaryl (1-
naphthyl-N-methylcarbamate) significantly increased the acute toxicity
of pentachlorophenol in aqueous solutions. Enhancement of toxicity by
carbaryl was a general phenomenon; potentiation was also observed when
the acute toxicities of 2,4-D n-butyl ester, dieldrin, and rotenone were
examined. This phenomenon was believed to have occurred because carbaryl
increased the uptake of the toxicant from the water. Other compounds
present in water also likely produce alterations in the toxic effects of
sodium pentachlorophenate. Furthermore, the toxicity of sodium penta-
chlorophenate may be decreased if appropriate substances are present in
the water. The toxicity of two or more compounds in combination is
worthy of additional investigation.
D.5.2.2.3 Bioconcentration and Biomagnification in Aquatic
Organisms — Bioconcentration is the ability of an organism to concentrate
a substance from an aquatic system. Biomagnification refers to the sub-
stance being found at successively higher concentrations with increasing
trophic levels in the food chain. Many aquatic organisms are capable of
pentachlorophenol bioconcentration. Pentachlorophenol may accumulate in
fish in two ways: (1) following acute exposure due to tissue storage
and a slow excretion rate or (2) by constant uptake during exposure to
constant ambient levels of pentachlorophenol. Accumulation in the latter
case results from the rate of uptake exceeding the excretion rate. Tissue
levels of pentachlorophenol under these circumstances depend on the ability
of the fish to excrete the compound and on the levels of pentachlorophenol
in the water. Kobayashi and Akitake (1975a) demonstrated that penta-
chlorophenol accumulation in the goldfish increased when the fish were
confined to culture media in which a constant level of pentachlorophenol
was maintained until either the fish died or the pentachlorophenol con-
tent was at a high chronic level. As discussed in Sections D.5.2.1.2 and
D.5.2.1.4, the reported studies do not provide sufficient data to draw
reliable conclusions on the long-term retention of pentachlorophenol in
aquatic species.
Pentachlorophenol biomagnification has not been clearly demonstrated
in the environment. Biomagnification has been demonstrated, however, by
Lu and Metcalf (1975) in a model aquatic ecosystem. A six-element food
chain included, plankton, green filamentous algae (Oedogonium cardiaeum).
snails (Physa sp.), water fleas (Daphnia magna), mosquito larvae (Culex
qu^nqu^fasc^atus), and mosquito fish (Gambusia affinis). The experi-
mental procedure used by these investigators is discussed in detail in
-------
325
Section D.5.2.1.3. An ecological magnification factor (defined as ratio
of concentration of pentachlorophenol in the organism to concentration
of pentachlorophenol in the water) was calculated for each member of the
model ecosystem. The value calculated for mosquito fish was 296; other
organisms had lower values: algae, 1.58; mosquito larvae, 16; snail,
121; and daphnia, 165. The correspondence between ecological magnifica-
tion factor and trophic level indicates that biomagnification likely
occurred. The ecological magnification factor of 11 other commonly used
organic compounds was also determined for the mosquito fish (Table D.5.26),
The value for pentachlorophenol is roughly intermediate to those for other
compounds tested.
TABLE D.5.26. ECOLOGICAL MAGNIFICATION OF
ORGANIC CHEMICALS BY MOSQUITO FISH
IN A MODEL AQUATIC ECOSYSTEM
., , Ecological
Compound .,-. . a
magnification
Aldrin 1,312
Aniline 6
Anisole 22
Benzole acid 21
Chlorobenzene 650
DDT 16,950
2,6-Diethylaniline 124
Hexachlorobenzene 1,166
Nitrobenzene 29
Pentachlorophenol 296
Phthalic anhydride 0
3,5,6-Trichloro-2-pyridinol 16
^Ratio of concentration of pentachlorophenol
in mosquito fish to concentration of pentachloro-
phenol in water.
Source: Adapted from Lu and Metcalf, 1975,
Table 1, p. 270. Reprinted by permission of the
publisher.
Lu and Metcalf (1975) noted that degradation of hexachlorobenzene
by members of the model community resulted in the formation of substantial
amounts of pentachlorophenol (Table D.5.27). The presence of pentachloro-
phenol as a metabolic breakdown product of hexachlorobenzene has a prece-
dent in higher organisms (Section D.6.2.2.5). Thus, the possibility that
pentachlorophenol levels in water may result from detoxification of hexa-
chlorobenzene should not be ignored. If hexachlorobenzene serves as a
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326
TABLE D.5.27. DISTRIBUTION OF HEXACHLOROBENZENE AND DEGRADATION PRODUCTS IN A MODEL AQUATIC ECOSYSTEM
Hexachlorobenzene
Compound
Total '"C
Hexachlorobenzene
Unknown 1
Pentachlorophenol
Unknown 2
Unknown 3
Unknown 4
Unknown 5
Polar
Unextractable
sf
0.83
0.72
0.42
0.35
0.26
0.10
0.05
0.0
Culture
water
26.8
9.34
0.31
0.25
0.08
0.22
9.60
6.95
Alga
(Oedogonium
cardia.ciffn)
43,700
37,100
1,430
2,330
1,090
Trace
655
1,110
Daphnia
(Daphnia
magna)
15,800
10,600
4,940
9,360
equivalent (ng/g)
Mosquito
(Culex
quinqui-
fasciatus)
36,900
24,500
1,350
1,790
152
1,330
7,810
Snail
(Physa
sp.)
27,600
25,000
1,190
450
331
674
Fish
(Gambusia
af finis)
17,000
10,900
1,470
4,670
Retardation factor determined by thin-layer chromatography in a solvent consisting of acetone
and benzene in ratio of 50:50 (v/v).
Source: Adapted from Lu and Metcalf, 1975, Table 8, p. 277. Reprinted by permission of the
publisher.
source of pentachlorophenol, this mechanism may account for the ubiquitous
presence of pentachlorophenol in the environment.
D.5.2.2.4 Detection and Avoidance Reactions — Fish are capable of
detecting sodium pentachlorophenate and demonstrate an avoidance reaction
to it in a gradient tank. Species differ, however, in the pentachloro-
phenol level which can be detected. Goodnight (1942) reported that vari-
ous minnows are able to detect sodium pentachlorophenate at levels greater
than 10 mg/liter; below 5 nig/liter, sodium pentachlorophenate was not
detected. Tomiyama and Kawabe (1962) reported that "guchi" fish can
detect pentachlorophenol at levels as low as 0.2 mg/liter. Cote (1972)
reported an avoidance response in juvenile Atlantic salmon when they
were exposed to 0.1 mg/liter sodium pentachlorophenate. The ability to
avoid high pentachlorophenol concentrations may increase the survival of
fish exposed to point sources of pentachlorophenol or sodium pentachloro-
phenate, but it is of little use against low-level, widespread contamina-
tion of waterways. Levels of pentachlorophenol which cause chronic
toxicity are below the threshold detection limits of fish.
D. 5.2.2.5 Carcinogenicity, Teratogenicity, and Mutagenicity — No
carcinogenic or mutagenic effects of pentachlorophenol on aquatic organisms
have been demonstrated. Developmental abnormalities in freshwater fish
exposed to pentachlorophenol have been described (Section D.5.2.2.2.3).
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327
SECTION D.5
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Toxic Effect of Pentachlorophenate, a Herbicide, on Fishery Organisms
in Coastal Waters: IV. The Effect on Venerupis philippinarum of
PCP Which Was Constantly Supplied or Adsorbed on Estuary Mud. Bull.
Jpn. Soc. Sci. Fish 28(4):422-425.
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332
60. Tsuda, T. , and T. Kariya. 1963. Studies on the Post-Mortem Identi-
fication of the Pollutant in the Fish Killed by Water Pollution:
III. Confirmation Method of Pentachlorophenate in the Fish. Bull.
Jpn. Soc. Sci. Fish. 29(9):828-833.
61. Turnbull, H., J. G. DeMann, and R. F. Weston. 1954. Toxicity of
Various Refinery Materials to Fresh Water Fish. Ind. Eng. Chem.
46(2):324-333.
62. Van Gelder, G. A., R. Zumwalt, and G. D. Osweiler. 1978. Personal
communication. College of Veterinary Medicine, University of Missouri,
Columbia.
63. Vermeer, K., R. W. Risebrough, A. L. Spaans, and L. M. Reynolds.
1974. Pesticide Effects on Fishes and Birds in Rice Fields of
Surinam, South America. Environ. Pollut. 7(3):217-236.
64. Walters, C. S. 1952. The Effects of Copper Naphthenate and Penta-
chlorophenol on Livestock. Proc. Am. Wood Preserv. Assoc. 48:302-313.
65. Webb, P. W., and J. R. Brett. 1973. Effects of Sublethal Concentra-
tions of Sodium Pentachlorophenate on Growth Rate, Food Conversion
Efficiency, and Swimming Performance in Underyearling Sockeye Salmon
(Onoor'nynchus nerka). J. Fish. Res. Board Can. 30(4) :499-507.
66. Whitley, L. S. 1967. The Resistance of Tubificid Worms to Three
Common Pollutants. Hydrobiologia 32(1-2):193-205.
67. Whitley, L. S., and R. A. Sikora. 1970. The Effect of Three Common
Pollutants on the Respiration Rate of Tubificid Worms. J. Water
Pollut. Control Fed. 45(2):R57-R66.
68. Yasuraoka, K., and Y. Hosaka. 1971. The Problem of Resistance of
Oneomelania Snail to Sodium Pentachlorophenate. Jpn. J. Med. Sci.
Biol. 24:393-394.
69. Zumwalt, R., G. A. Van Gelder, G. D. Osweiler, and C. W. Foley. 1977.
Blood Residues in Cattle Fed Technical Pentachlorophenol (abstract).
58th Meeting of Conference of Research Workers in Animal Disease,
November 29, 1977, Chicago.
-------
D.6 BIOLOGICAL ASPECTS IN HUMANS
D.6.1 METABOLISM
D.6.1.1 Uptake and Absorption
D.6.1.1.1 Inhalation — Atmospheric pentachlorophenol can be pres-
ent as a vapor, a dust, or an aerosol. The small, but substantial,
vapor pressure of pentachlorophenol — 0.00011 to 0.12 mm Hg at 20°C to
100°C (Bevenue and Beckman, 1967) — may allow toxic levels of vapor to
build up in hot, enclosed areas. The maximum atmospheric concentration
recommended by the American Industrial Hygiene Association (1970) is
0.5 mg pentachlorophenol or sodium pentachlorophenate per cubic meter of
air. The maximum allowable concentration suggested by Plakhova (1966)
of the Soviet Union is 0.1 mg/m3. Minimum lethal concentrations in air
have not been defined. Concentrations in air which do not cause death
can cause painful irritation of the nose. This general upper respira-
tory distress, including violent coughing and sneezing, should prevent
individuals from inhaling vapor or dust concentrations which produce
adverse systemic effects. However, some tolerance is found in persons
who routinely handle these materials. Dust and mist concentrations of
>1 mg/m3 pentachlorophenol or sodium pentachlorophenate cause distress
in unacclimated persons (American Industrial Hygiene Association, 1970);
concentrations as high as 2.4 mg/m3 can be tolerated by those conditioned
to exposure. Most information on routes of entry of pentachlorophenol
into the body deals with dermal exposure and accidental or intentional
ingestion. Some entry of pentachlorophenol by the respiratory route was
inferred in the following studies.
Gordon (1956) reported nine cases of pentachlorophenol poisoning
from 1953 to 1956. Five persons died within 16 to 30 hr following onset
of symptoms. Three of the five fatalities occurred from spraying sodium
pentachlorophenate on sugar cane or pineapple fields. One death resulted
from spraying weeds with a highly concentrated pentachlorophenol-diesel
oil mixture, and the fifth fatality occurred following the preparation of
a pentachlorophenol formulation. The three fatalities which resulted
from spraying sodium pentachlorophenate probably involved some skin con-
tamination, but pathological changes of the lungs were noted at autopsy.
Autopsy findings in two cases revealed that the lungs had "the histo-
logical appearance of gross congestion and widespread intraalveolar
hemorrhage" (Gordon, 1956). Some contamination through the respiratory
route was inferred although concentrations of pentachlorophenol in the
air were not known. Of the four nonfatal cases reported, two involved
pineapple spraying and one occurred at a sawmill, apparently from opera-
tion of kilns in which timber soaked in sodium pentachlorophenate solu-
tion was dried. The timber was not handled by hand; therefore, skin
contamination was unlikely.
Blair (1961) described three cases of sodium pentachlorophenate
poisoning in Southern Rhodesia, two of which were fatal. The affected
persons were involved in spraying a sodium pentachlorophenate solution
333
-------
334
on a farm to control snails. One fatality resulted from gross skin con-
tamination with the concentrated solution. The other two were preparing
a solution from sodium pentachlorophenate powder under very windy condi-
tions. The powder was blown into their faces, causing smarting of the
eyes and irritation of the nose; one of the workers died soon afterwards.
Mason et al. (1965) reported two fatal cases of pentachlorophenol
poisoning at a chemical plant. The workers were packaging the powder
and "inhaled considerable amounts of dust particles of the chemical."
Autopsy findings were not remarkable; in both cases, however, congested,
edematous lungs with areas of marked alveolar hemorrhage were found.
Nine cases of fatal pentachlorophenol intoxication occurred in
Sarawak, Borneo (Menon, 1958). Although gross skin contamination was
common among workers dipping timber in pentachlorophenol preservative
solutions, autopsy findings in two of the nine fatalities showed conges-
tion and acute edema of the lungs. The author inferred a respiratory
factor in these two fatal intoxications.
Respiratory uptake also apparently was involved in a fatal penta-
chlorophenol poisoning in Winnipeg, Canada (Bergner, Constantinidis,
and Martin, 1965). The individual worked in a factory which made window
sashes and wooden frames. All wood was treated with a wood preservative
containing 4.1% pentachlorophenol before it was shipped. The worker
dipped the wood in the preservative with bare hands, and overt skin con-
tamination occurred. However, it was also stated that "a drying pan
with a fan above it was provided, where the wood dried at room tempera-
ture, but there was a distinct odour in the room and ventilation appeared
to be inadequate. This impression was later confirmed by special ven-
tilation studies."
A clearer case of poisoning by inhalation of pentachlorophenol vapor
was reported in Sacramento, California (Anonymous, 1970). A woman, after
moving into a new house, noticed that her house plants began to die. In
turn, she began to lose weight rapidly and to become weak. Three months
later, after losing 9 kg, she was hospitalized. The diagnosis was penta-
chlorophenol poisoning. A preservative had been applied by the builder
to the interior redwood of the home to prevent its turning gray, and a
strong odor was present. Ingestion of the compound seems highly unlikely,
but some dermal exposure cannot be ruled out. It cannot be inferred that
the woman was only exposed to pentachlorophenol vapor. Pentachlorophenol
solutions that use light solvents such as mineral spirits do not always
contain enough cosolvents (antiblooming agents) to hold the pentachloro-
phenol in solution in the wood. When this occurs, pentachlorophenol will
recrystallize on the surface of the wood (blooming). One must examine
the wood carefully for a white to light gray, dustlike surface residue.
These small particles can become airborne through brushing, air currents,
or household cleaning activities. These crystals also increase the sur-
face area available for vaporization of pentachlorophenol.
A common feature of most of the above cases is an elevated ambient
temperature. Bergner, Constantinidis, and Martin (1965) suggested that
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335
the increased volatility of pentachlorophenol at higher temperatures
results in greater atmospheric quantities of pentachlorophenol available
for inhalation.
Pentachlorophenol absorption by the respiratory route was examined
critically by Casarett et al. (1969). Two persons were exposed to penta-
chlorophenol in an enclosed area where the preservative was applied with
a brush. Ambient levels of pentachlorophenol in the air and respiratory
rates were monitored (Table D.6.1 and Figure D.6.1). No marked change
in the pentachlorophenol concentration in the urine occurred until about
one day after exposure; peak values occurred one or two days after
exposure.
TABLE D.6.1. INHALATION OF PENTACHLOROPHENOL BY
TWO HUMAN SUBJECTS AND RECOVERY IN URINE
Pentachlorophenol value Subject A Subject B
Mean air concentration, yg/m3 230 432
Calculated exposure dose, yg 91 147
Recovered in urine, yg 80 112
Recovered in urine, % 88 76
, Recovered 160 hr after exposure.
Recovered 120 hr after exposure.
Source: Adapted from Casarett et al., 1969, Table
III, p. 363. Reprinted by permission of the publisher.
Not unexpectedly, pentachlorophenol has been found in the air of
wood treating plants. Wyllie et al. (1975) sampled air at 11 sites at
five different times in a plant treating 2.5 million board feet of lumber
annually. Average pentachlorophenol levels ranged from 263 to 1888 ng/m
(0.26 to 1.8 yg/m3). The highest level reported was 15 yg/m3 in a sample
from the pressure treating room. The air samples were collected for an
average of 6 hr. Pentachlorophenol levels in the dip tank area ranged
from 12 to 800 ng/m3 and in storage areas from 9 to 900 ng/m3. Penta-
chlorophenol in serum of workers was on the order of 1 to 2 mg/liter;
urinary levels ranged from 0.08 to 0.3 mg/liter. The highest level in
serum was 3.9 mg/liter. Levels in a control were 0.04 to 0.06 mg/liter
in serum and 0.004 mg/liter in urine.
A survey of workers in a wood preservation operation indicated a
substantial pentachlorophenol content in the blood and urine as compared
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336
ORNL-DWG 78-10531
V SUBJECT B
O SUBJECT A
0 20 40 60 80 100 120 140 160
TIME AFTER EXPOSURE (hr)
Figure D.6.1. Pentachlorophenol in urine of two subjects following
respiratory exposure. Source: Adapted from Casarett et al. , 1969,
Figure 3, p. 363. Reprinted by permission of the publisher.
with nonoccupationally exposed people (Figure D.6.2). Casarett et al.
(1969) stated, "The workers in this study unquestionably sustain some
dermal exposure, although protective gloves and barrier creams are used.
Data from air samples obtained in the plants were not given because the
method of sampling was not properly characterized. Nevertheless, they
demonstrated qualitatively that significant concentrations of penta-
chlorophenol were present in the plant atmosphere. Under the conditions
of widespread dissemination in the yard, and the prevalent temperature
and wind, at least part of the exposure of the workers must be considered
to occur via the respiratory tract."
Plakhova (1966) reported that the average lethal concentration of
sodium pentachlorophenate was 240 mg/m3 for mice and 341 mg/m3 for guinea
pigs. Exposure of animals (type not given) to sodium pentachlorophenate
at a concentration of 23 mg/m3 for 4 hr daily for four months resulted
in a decrease in weight, erythrocytes, and hemoglobin and in an increase
in leucocytes and eosinophils.
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337
ORNL-OWG 78 — 10532
100
10
<
s
5 1
o
z
UJ
r
a.
o
a:
o
_
i
o
<
H
Z
UJ
a.
0.1
0.01
T
O WOOD TREATERS
• NONOCCUPATIONALLY
EXPOSED PEOPLE
0.01 0.1 1 10 100
PENTACHLOROPHENOL IN URINE (mg/liter normalized to 1 osmole)
Figure D.6.2. Pentachlorophenol in paired blood and urine samples
of wood treaters and nonoccupationally exposed people. Source: Adapted
from Casarett et al. , 1969, Figure 5, p. 364. Reprinted by permission
of the publisher.
Hoben, Ching, and Casarett (1976a, 1976fr, 1976c) and Hoben et al.
(1976) reported an experimental method for evaluating the toxicity of
sodium pentachlorophenate inhaled by rats. These authors claimed an
LD50 for an inhaled sodium pentachlorophenate aerosol of 11.7 mg/kg body
weight. This conclusion, however, is difficult to substantiate based on
the methods and results presented. The paper describing the experiment
(Hoben, Ching, and Casarett, 1976&) does not state the aerosol concen-
tration nor the vehicle used to dissolve the sodium pentachlorophenate.
The authors stated that the aerosol mixture was continuously sampled
throughout the experiments and that desired doses of sodium pentachloro-
phenate were achieved by varying the exposure time. Unfortunately,
neither the actual aerosol concentrations nor exposure times were reported,
Only one of these four documents reports the actual aerosol concentration
(i.e., when the exposure chamber was calibrated) (Hoben, Ching, and
Casarett, 1976a): "To test reproducibility of the aerosol output a PCP
solution containing 10 g PCP, 6 ml glycerol and 1.7 g NaOH in 100 ml
water was atomized four times for periods of 20 minutes. The aerosol
was collected at a flow rate of 0.5 1/min. The results lay between 761
and 802 mg PCP with a standard error of 1.7%." If one calculates the
dose of sodium pentachlorophenate delivered to rats under these condi-
tions for the reported 28- to 44-min exposures (Hoben, Ching, and
Casarett, 19762?) , the values ranged from 795 mg/kg body weight to 1249
mg/kg body weight. The large discrepancy between these calculated values
and the reported LDSO of 11.7 mg/kg body weight suggests that the actual
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338
inhalation experiments were conducted under much different conditions.
It is not possible to resolve this question based on the data provided
and attempts to contact the authors were unsuccessful. Thus, the reported
LD50 value must be considered questionable.
Except for the suggestion by Bergner, Constantinidis, and Martin
(1969) that increased ambient temperatures result in increased volatility
of pentachlorophenol and sodium pentachlorophenate, causing increased
concentrations in the atmosphere, no investigations defined the factors
responsible for the uptake of pentachlorophenol or sodium pentachloro-
phenate from the atmosphere. Specific quantitative data concerning the
effect of the chemical and physical forms of these substances on absorp-
tion by the respiratory tract are not available.
D.6.1.1.2 Ingestion — Pentachlorophenol is repellent to laboratory
animals. The food intake by rats decreased when their diet contained
pentachlorophenol, and cats refused salmon treated with pentachlorophenol
(Deichmann et al. , 1942). The level in the rat food was approximately
300 to 600 mg/kg. At 125 to 250 mg/kg, cats refused to eat, but levels
equivalent to 30 to 60 mg/kg were apparently consumed.
Experiments with animals confirm that absorption from the gastro-
enteric tract is common after ingestion of pentachlorophenol. Kehoe,
Deichmann-Gruebler, and Kitzmiller (1939) administered an 11% solution
of pentachlorophenol in olive oil to rabbits. They stated that since
the rectal temperatures of these animals rose slowly, the absorption of
pentachlorophenol from the gastrointestinal tract was slow. Conversely,
investigations by Deichmann et al. (1942) indicated that the absorption
of sodium pentachlorophenate (18 mg/kg) from the stomach of the rabbit
was almost immediate, reaching a peak of 2.4 mg per 100 g of blood in
7 hr (Figure D.6.3). Absorption began almost immediately following a
dose of sodium pentachlorophenate equivalent to 18 mg/kg or more. The
blood level reached a peak after about 7 hr when a dose of 37 mg/kg was
administered. The findings of Machle, Deichmann, and Thomas (1943)
confirm the rapid appearance of sodium pentachlorophenate in blood and
urine of rabbits following oral administration (Figure D.6.4).
Translocation from the abdominal cavity to the digestive tract has
been demonstrated in mice (Jakobson and Yllner, 1971). Carbon-14—labeled
pentachlorophenol was injected intraperitoneally, and the tissue distri-
bution of the compound was followed by autoradiography. Within 4 hr
after injection, pentachlorophenol was detected in the fundus wall of the
stomach and in the stomach and intestinal contents.
Braun et al. (1977) showed that the half-life for absorption of
[ C]pentachlorophenol after ingestion by rats was 1.3 ± 0.4 hr; the
peak plasma concentration occurred 4 hr after ingestion. A dose of 0.1
mg/kg resulted in a peak plasma level of 0.248 mg/liter. The calculated
99% of steady-state value was 0.491 mg/liter, which would be reached
/fS^N dayS °f in8estion of O-1 mg/kg per day. Braun and Sauerhoff
(1976) administered a single oral dose of 10 mg [»*C]pentachlorophenol
per kilogram in corn oil to three male and three female rhesus monkeys.
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339
ORNL-DWG 78-<052<
20 30
TIME (hr)
Figure D.6.3. Pentachlorophenol in blood of rabbits after a single
oral dose of sodium pentachlorophenate. Source: Adapted from Deichmann
et al., 1942, Figure 1, p. 110. Reprinted by permission of the publisher.
The half-lives for absorption were 3.6 hr in the male and 1.8 hr in the
female.
No studies addressed the question of how the physical form of penta-
chlorophenol affects its absorption across the intestinal tract. Some
suggestive evidence can be obtained, however, relating to the relative
toxicities of sodium pentachlorophenate and pentachlorophenol. The toxic-
ity of pentachlorophenol is approximately twice as great as that of
sodium pentachlorophenate administered by the oral or cutaneous routes.
According to Kehoe, Deichmann-Gruebler, and Kitzmiller (1939), the
smallest oral dose of pentachlorophenol in olive oil resulting in the
deaths of rabbits was 110 mg/kg; the smallest lethal dose of sodium
pentachlorophenate in aqueous solution was 250 to 300 mg/kg. Similar
findings were reported by Deichmann et al. (1942) and by Dow Chemical
Company (1969a, 1969Z?) . This difference in toxicity was not apparent in
guinea pigs (Flickinger, 1971). The toxicities of pentachlorophenol and
sodium pentachlorophenate are similar when the compounds are administered
intravenously and intraperitoneally; thus, the difference in toxicity ot
the two forms administered via the oral or cutaneous route may result
from differential absorption by the intestinal tract and the skin.
Reports of human intoxication with pentachlorophenol via the oral
route are rare. Three of nine fatal cases reported by Menon (1W8;
appeared to involve ingestion. The individuals involved were engaged in
a timber dipping operation with pentachlorophenol preservative solution.
Although overt, gross skin contamination was common, autopsy reports
indicated inflamed gastric mucosa; thus, a contribution to intoxicati
by the oral route was inferred. A report from Australia (Gordon, ±«o,
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340
ORNL-DWG 78-<0522
400
350 -
URINE
O BLOOD
50 mg/kg
<00mg/kg
200 mg/ kg
TIME
Figure D.6.4. Pentachlorophenol in blood and urine of rabbits
exposed to a single oral dose. Source: Adapted from Machle, Deichmann,
and Thomas, 1943, Figures 13, p. 193. Reprinted by permission of the
publisher.
also suggested intoxication by the oral route. The individual was mixing
a 1% solution of sodium pentachlorophenate. Some of the solution was
siphoned into another container, and apparently some was swallowed.
Death ensued about 9 hr after onset of symptoms.
A clear-cut case of pentachlorophenol poisoning by ingestion was
reported by Blair (1961). The case involved an African who died in July
1960 as a result of consuming food contaminated accidentally with sodium
pentachlorophenate. He had collected maize meal from a grain storage
bin in the dark and had prepared maize meal porridge for himself and a
friend. Early the next morning the African called for help and was
found to be sweating profusely. He did not vomit or have convulsions
and died about 1 hr later. Later inspection revealed that a small tin
of "insecticide" used against rodents and insects was present in the
grain bin. It was found, in fact, to contain technical grade sodium
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341
pentachlorophenate. The maize meal porridge was later analyzed and was
found to contain 216 mg of sodium pentachlorophenate per gram of porridge,
Ingestion of pentachlorophenol is probably rare among humans. Only
in fairly exceptional circumstances, such as suicidal intent or extra-
ordinary insensitivity, is someone likely to ingest a compound of such
noxious character. If taken internally, vomiting would probably result
before much of the compound could be absorbed (Flickinger, 1971). How-
ever, possible ingestion of extremely small amounts of pentachlorophenol
in the diet cannot be ignored. In areas where sodium pentachlorophenate
or pentachlorophenol is widely applied, contamination of food crops is
possible. The significance of these small amounts of pentachlorophenol
which may be consumed by human populations is discussed in Section
D.6.2.2.4.2. Levels in food and estimated dietary intake of pentachloro-
phenol are discussed in Sections D.6.2.2.5 and D.8.2.
D.6.1.1.3 Cutaneous Absorption — Most of the reported cases of
pentachlorophenol intoxication in humans involved direct absorption of
pentachlorophenol or its sodium salt through the skin. According to the
American Industrial Hygiene Association (1970), "Solutions of either as
dilute as about 1% may cause irritation if contacts are prolonged or
repeated frequently. However, solutions as dilute as 0.1% are not likely
to cause adverse local effects. Absorption through the skin is reported
if the contact is prolonged beyond five or ten minutes or for repeated
contacts for shorter time periods. If contacts are continued over an
extended period of time (months to years), an 'acne-like' dermatitis is
possible."
The first incident of serious pentachlorophenol intoxication was
reported by Truhaut, Boussemart, and L'Epe'e (1952). The individuals
affected were involved in a timber preservation operation in south-
western France. The timber was dipped in 3% solutions of sodium penta-
chlorophenate and tetrachlorophenate without protection for the workers.
The men immersed their hands and forearms in the solution, and their
vests and overalls were contaminated. Pentachlorophenol was found in
amounts ranging from 3 to 10 mg/liter in the urine of 16 men who had
been working for two months. The toxic effects were severe enough to
cause death in two cases.
Gordon (1956) reported nine cases of pentachlorophenol poisoning in
Australia, five of which were fatal. The workers were spraying pineapple
fields with an aqueous solution of sodium pentachlorophenate. They wore
shorts, often without a shirt, and frequently wore no shoes. In this
particular method, the spray was directed towards the ground, which per-
haps reduced inhalation, but this certainly increased contamination of
the lower limbs.
Skin absorption of pentachlorophenol was implicated in two fatali-
ties reported by Bergner, Constantinidis, and Martin (1965). The men
were employed by a firm which manufactured window sashes. These sashes,
prior to shipment, were dipped in a preservative solution consisting of
pentachlorophenol, a petroleum solvent, and unnamed inert ingredients.
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342
In both cases, the workers were involved in dipping operations and a^
not wear gloves.
A definite case of pentachlorophenol absorption through the skin
was reported by Bevenue, Haley, and Klemmer (1967). A man cleaned a
paint brush with a solution which, it was subsequently determined, con-
tained pentachlorophenol. Analysis of the solution used to clean the
brush indicated a 0.4% concentration of pentachlorophenol and a trace
amount of tetrachlorophenol, which suggested that the paint thinner or
brush cleaner solvent had been added to a can that contained a residual
amount of pentachlorophenol. Skin irritation persisted despite a
thorough washing. Two days following exposure a 24-hr urine specimen
was analyzed. Subsequent urine samples (each was the first void in the
morning) were also analyzed. The data indicate that pentachlorophenol
was absorbed through the skin and that elimination of the compound from
the body was gradual (Table D.6.2).
Chapman and Robson (1965) reported a case of serious intoxication
in England. The patient, a girl 3.5 years of age, developed fever,
intermittent delirium, and rigors during the night. After she was
admitted to a hospital, urine analysis indicated a pentachlorophenol
content of 6 mg per 100 ml of urine. Examination of the house showed
TABLE D.6.2. RESIDUES OF PENTACHLOROPHENOL IN
URINE OF INDIVIDUAL AFTER CUTANEOUS ABSORPTION
_. Pentachlorophenol
Date . . * a
, , in urine"
sampled (llg/iiter)
1-17-67
1-19-67
1-20-67
1-30-67
2-6-67
2-17-67
3-7-67
236
80
90
48
64
23
17
Residue
as ratio of
initial analysis^
(%)
34
38
20
27
10
7
,Data not corrected for percent recoveries.
Recovery values of fortified samples were
89% to 92% with detection limits of 3 yg/liter.
Source: Adapted from Bevenue, Haley, and
Klemmer, Table 1, p. 295. Reprinted by permis-
sion of the publisher.
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343
that the cold-water storage tank in the roof was contaminated with an
insecticide mixture that had been used to spray the roof timbers before
the family moved in, some 13 days previously. The mixture contained
pentachlorophenol, 3-naphthol, and dieldrin in a tractor oil—like solvent.
Scum was evident on the bath water. Drinking water was obtained from
the public water main; therefore, except for brushing her teeth, the
patient was unlikely to have drunk much contaminated water. Absorption
through the skin was the most probable route of uptake. This is a case
of multiple intoxication. Dieldrin, as well as pentachlorophenol, is
absorbed through the skin, and the neurologic signs reported are more
consistent with dieldrin toxicosis than with pentachlorophenol toxicosis.
The high pentachlorophenol content of the urine also indicates signifi-
cant pentachlorophenol exposure.
From April to August 1967, 20 newborns had an unusual disease char-
acterized by profuse generalized diaphoresis, fever, tachycardia, tachyp-
nea, hepatomegaly, and acidosis (Armstrong et al., 1969). Nine of the
infants were affected seriously and two died. Intense investigation of
the hospital premise resulted eventually in the identification of a
laundry product which contained sodium pentachlorophenate. An antimicrobial
laundry neutralizer containing pentachlorophenol had been used in the
final rinse of hospital linens. The ingredients listed on the labels
of two 45-kg drums of powder were as follows: sodium pentachlorophenate,
22.9%; 3,4,4'-trichlorocarbanilide, 4.0%; sodium salts of other chloro-
phenols, 3.2%; and inert ingredients, 69.9%. High concentrations of
this product were found in diapers and hospital linens. High penta-
chlorophenol levels were detected in the serum and urine of infants,
nurses, and expectant mothers exposed to the linens (Table D.6.3).
According to Armstrong et al. (1969), "Sodium pentachlorophenate is
readily absorbed through the skin, and, since it is a water-soluble
substance, its absorption would be enhanced by urine or moisture on the
skin." Armstrong et al. (1969) suggested that the increased toxicity
of these compounds to infants was a result of their relatively immature
renal function, which might have caused pentachlorophenol to accumulate.
In addition, pentachlorophenol excreted in urine may have been reabsorbed
from wet diapers. For example, a 10-min exposure of hands to 0.4% penta-
chlorophenol resulted in urine concentrations of 236 mg/liter (Bevenue,
Haley, and Klemmer, 1967).
According to Dow Chemical Company (1969a, 19692>), solid pentachloro-
phenol is not absorbed through the skin in acutely toxic amounts, but
cutaneous contact with solid sodium pentachlorophenate can result in
systemic intoxication. One report appears to contradict these state-
ments. Nomura (1953) reported one fatal case and two nonfatal cases of
systemic intoxication by pentachlorophenol. The workers were involved
in centrifuging, drying, and packaging pentachlorophenol following its
manufacture. Extensive skin contact was believed to be responsible for
the poisonings.
Animal studies confirm that pentachlorophenol and sodium pentachloro-
phenate are easily absorbed via the cutaneous route. Table D.6.4 summa-
rizes the toxicity of pentachlorophenol and sodium pentachlorophenate in
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344
TABLE D.6.3. LEVELS OF PENTACHLOROPHENOL IN SERUM AND URINE FROM HEALTHY
PERSONS AT HOSPITAL WHERE A PENTACHLOROPHENOL POISONING INCIDENT OCCURRED
Pentachlorophenol level
Time relationship
Persons to discontinuation
sampled of antimicrobial
laundry neutralize
6 infants
9 infants
1 infant
5 nurses
5 nurses
2 expectant
mothers
-2 days
+2 weeks
+8 weeks
-2 days
+8 weeks
+8 weeks
Mean
18.7
9.2
2.0
5.4
0.9
1.9
(mg/1
Serum
Range
11.3-25.6
3.3-17.5
1.7-12.6
0.5-1.9
1.8-2.0
iter)
Mean
0.34
0.10
0.06
0.08
0.37
Urine
Range
0.02-0.70
0.01-0.66
0.04-0.14
0.28-0.46
Source: Adapted from Armstrong, R. W., E. R. Eichner, D. E. Klein,
W. F. Barthel, J. V. Bennett, V. Jonsson, H. Bruce, and L. E. Loveless, 1969,
Pentachlorophenol Poisoning in a Nursery for Newborn Infants: II. Epidemi-
ologic and Toxicologic Studies, J. Pediatr. 75:317-325. Reprinted by
permission of the publisher.
various solvents to experimental animals. The toxicity of pentachloro-
phenol, as defined by the minimum lethal dose, varies depending on the
solvent used. It appears to be most toxic in petroleum solvents. It
is impossible to compare directly the toxicity of pentachlorophenol and
sodium pentachlorophenate via the cutaneous route because the two com-
pounds have different solubilities in any given solvent. A general
comparison, however, indicates that pentachlorophenol in organic solvents
is considerably more toxic to experimental animals than sodium penta-
chlorophenate in aqueous solution. No investigations addressed the ques-
tion of why the organic solvent affected the cutaneous absorption of
pentachlorophenol. Kehoe, Deichmann-Gruebler, and Kitzmiller (1939)
investigated the possibility that the specific gravities of the solvents
or their ability to dissolve pentachlorophenol may affect cutaneous
toxicity, but no correlations were found. Diechmann et al. (1942) noted
that soap and water were more effective in removing pentachlorophenol or
sodium pentachlorophenate from the skin than was alcohol. Investigations
of the mechanism by which these compounds pass through the skin and
specific quantitative data are badly needed.
D.6.1.2 Transport and Distribution
D.6.1.2.1 In Blood — Whether pentachlorophenol is taken up through
the skin, via the respiratory tract, or through ingestion, it is distrib-
uted in and transported by the blood. Substantial data indicate that
-------
TABLE D.6.4. MINIMUM LETHAL DOSES OF PENTACHLOROPHENOL AND SODIUM
APPLIED CUTANEOUSLY TO EXPERIMENTAL ANIMALS
'ENTACIILOKOPHENATE
. . , Composition of
Animal , r. , . ,
solution applied
Albino rabbit 5% in olive oil
5% in 95% ethanol
10% in 95% ethanol
10% in 99% ethanol
10% in corn oil
5% in No. 1 fuel oil
5% in furnace oil
5% In No. 3 fuel oil
5% in Dione oil
5% in pale paraffin
oil
1.8% In pine oil
Rabbit Solid
In organic solvent
5% in fuel oil
11% in olive oil
20% in prophylone
^iycol
Rabbit 10% aqueous
27,: aqueous
10% aqueous
20% aqueous
107, aqueous
(lulnea pip, 2% aqueous
.Mini mum Lethal dose was not achl
( Absorpt Ion ol pent aeh 1 oropbonol
At lower value m> animals tiled:
Minimum Time required
lethal dose for death
(mg/kg) (hr)
Pentachlorophunol
>180"
>150"
>lllla
-309"
r-326"
60-70 1.5-4
90-100 1.5-3
130-170 6
110-120 5-6.5
>150"
40-50 9-22
200"
.1 00-200' '
60-1 70
350
50-200' '
Sod Him pent aeh 1 orophona t e
250 5-H
257 2.5
45()-f>00 1-20
100-3001'
200
2 (i(> 1
I'ved .
was not de t ec t cd .
nl (inner value all anlnialK
-------
346
pentachlorophenol is present in the blood following uptake by any of
these routes. Autopsies of victims poisoned by pentachlorophenol have
shown invariably the presence of pentachlorophenol in the blood. Penta-
chlorophenol is excreted primarily in the urine; analyses of urine and
blood following administration of pentachlorophenol to experimental
animals show a rough parallel between urine and blood concentrations.
It has been suggested that urinary concentrations be used as a tool for
diagnosing pentachlorophenol exposure in humans.
Machle, Deichmann, and Thomas (1943) studied the relationship be-
tween blood and urinary concentrations of pentachlorophenol in rabbits
(Figure D.6.4). Single oral doses of sodium pentachlorophenate were
administered to rabbits. Eight hours after administration of 50, 100,
and 200 mg of sodium pentachlorophenate, the blood levels were 4, 10,
and 13 mg per 100 ml, respectively, and the urinary concentrations were
92, 344, and 372 mg per 100 ml respectively. These data demonstrate a
sharp rise in urinary pentachlorophenol in response to a slight increase
in the level of pentachlorophenol in the blood. This correlation between
urinary and blood concentrations has been shown before and is the reason
for the suggestion that urinary determinations may offer a sensitive
means of estimating the extent of human absorption of pentachlorophenol.
Accumulation of pentachlorophenol in the blood following repeated
small doses has been shown (Deichmann et al. , 1942). Daily feeding of
pentachlorophenol (3 mg/kg body weight) to rabbits for 90 days caused
accumulation of the compound in concentrations up to 0.6 mg per 100 ml.
A threshold level was seen, however. Machle, Deichmann, and Thomas
(1943) demonstrated that rabbits given 90 daily doses of sodium penta-
chlorophenate at a level of 1 mg pentachlorophenol per kilogram of body
weight resulted in levels of 1.5 to 3.0 mg/liter in blood.
Pentachlorophenol is apparently not bound to the cellular constit-
uents of blood (Bevenue et al., 1968; Larsen et al., 1972). It is
eliminated fairly rapidly by the urinary route in both experimental
animals and in humans. However, a study of human excretion rates
indicates the possibility of a two-component urinary excretion (Figure
D.6.5). This two-component excretion curve led to the suggestion by
Casarett et al. (1969) that a binding of pentachlorophenol to plasma
proteins may account for the second, slower excretion rate. This
suggestion is particularly important because it indicates that some
pentachlorophenol would be available for redistribution to tissues
following an initial rapid excretion.
Casarett et al. (1969) examined the urine and plasma of nonoccupa-
tionally exposed persons and of workers in wood treating plants in
Hawaii. Pentachlorophenol concentrations in plasma and in urine were
uniformly higher among exposed persons (Figure D.6.2). However, a low
concentration of pentachlorophenol was discovered in the urine and plasma
of nonoccupationally exposed persons (Section D.6.2.2.4.2). This study
suggests a ratio of pentachlorophenol in blood to pentachlorophenol in
urine of between 1.5 and 2.5 (Figure D.6.2).
-------
347
(00
ORNL-DWG 78-t0535
V SUBJECT A
O SUBJECT 8
20 40 60
TIME AFTER EXPOSURE (hr)
Figure D.6.5. Pentachlorophenol remaining in two human subjects
after inhalation exposure. Source: Adapted from Casarett et al., 1969,
Figure 4, p. 364. Reprinted by permission of the publisher.
Higher pentachlorophenol concentrations in urine than in blood are
frequently reported for acute intoxications. Animal studies with a
single dose also show this pattern. Two possible explanations for this
reversal are (1) an effect of pentachlorophenol on the kidney or (2)
sufficient amounts of pentachlorophenol are carried into urine by plasma
proteins from the blood to cause this effect. Casarett et al. (1969)
stated that the data in Figure D.6.6 indicate the binding of pentachloro-
phenol with elements of the blood: "Blood and urine PCP concentrations
were linearly related up to about 0.1 ppm, above which the plasma levels
reached a plateau approaching 100 ppm with increasing levels of PCP in
the urine. These data suggest the possibility of binding to plasma pro-
teins With an apparent upper limit of plasma concentration and some
limitation of urinary excretion rates, it is quite probable that some of
the PCP would be available for redistribution to tissues."
Braun et al. (1977) administered single oral doses of [1AC]penta-
chlorophenol in corn oil to rats at rates of 10 and 100 mg/kg. Peak
plasma concentrations of 30 to 40 mg/liter were reached in 4 to 6 hr
after the 10 mg/kg exposure. They demonstrated that 95% of the plasma
pentachlorophenol was bound to protein. In monkeys given a single dose
of 10 mg/kg, peak plasma levels of 10 to 30 mg/liter were attained \l
to 24 hr after administration. From the pharmacokinetic model, it was
calculated that 90% of the plasma steady state would be reached after
ten daily doses, and the approximate plasma concentration would be 45
mg/liter.
D.6.1.2.2 Organ Distribution - Data for tissue distribution follow-
ing human uptake of pentachlorophenol are derived mainly from autopsi
-------
348
100
ORNL-DWG 78-40533
r
0.01
0123
PENTACHLOROPHENOL IN URINE (mg/liter normalized to 1 osmole)
Figure D.6.6. Relationship between pentachlorophenol concentra-
tions in plasma and urine. Source: Adapted from Casarett et al., 1969,
Figure 6, p. 365. Reprinted by permission of the publisher.
of fatal cases of pentachlorophenol poisoning. Tables D.6.5 through
D.6.8 summarize autopsy findings in seven cases of fatal pentachloro-
phenol intoxication. It is, of course, difficult to base conclusions
on data of this type. However, the presence of pentachlorophenol in the
liver, kidneys, and — in some cases — the stomach is a common finding.
The presence of pentachlorophenol in other tissues may depend on the
route of exposure.
From these data, levels of pentachlorophenol associated with acute
lethal toxicosis can be estimated. Levels in the blood, liver, and
kidney are most meaningful. Levels in urine can vary depending on how
much urine was in the bladder at the time of ingestion. Residues
associated with death are 50 to 176 mg/kg in blood, 62 to 225 mg/kg in
the liver, and 28 to 123 mg/kg in the kidney. Haley (1977) reported an
attempted suicide by a 71-year-old male whose peak level of pentachloro-
phenol in blood was 155 mg/kg. He was saved by an aggressive therapy
that included gastric lavage, diuretics, maintenance of electrolyte
balance, and intravenous fluids to promote renal excretion.
A study by Armstrong et al. (1969) is interesting because it in-
cludes the only analysis of fatty tissue from a human acutely exposed
to pentachlorophenol. The case involved an infant exposed to lethal
concentrations of sodium pentachlorophenate in diapers and hospital
linens (Section D.6.1.1.3). The data indicate a 25% greater concentra-
tion of pentachlorophenol in fat than in other tissues (Table D.6.6).
Significant concentrations of pentachlorophenol have been found in the
adipose tissue of nonoccupationally exposed persons (Shafik, 1973).
This aspect of pentachlorophenol accumulation has not been investigated
thoroughly.
-------
349
TABLE D.6.5. AUTOPSY ANALYSES OF TWO HUMANS FATALLY
POISONED BY PENTACHLOROPHENOL
Pentachlorophenol
(tng/100 g tissue)
L7ULJJ C^-U
A
B
Control
tJpc:*_-Liiidl
Blood
Liver
Kidney
Brain
Urine
Blood
Liver
Brain
Liver fortified with
9.28 mg/100 g of
pentachlorophenol
Detected
10.8, 11.1
8.7, 9.1
8.0, 9.2
2.0, 2.9
36, 37
8.3, 7.5
6.7, 6.4
1.2, 0.74
6.3 (69%
recovery)
Corrected
average3
15.6
13.4
12.3
3.5
52
11.3
9.4
1.4
Correction for recovery value = pentachlorophenol
detected x 1.43.
Source: Adapted from Mason et al., 1965, Table IV,
p. 145. Reprinted with permission from the Journal of
Forensic Sciences, April 1965, published by Callaghan &
Company, 3201 Old Glenview Road, Wilmette, Illinois 60091.
TABLE D.6.6. CONTENT OF PENTACHLOROPHENOL
IN TISSUES OF A FATALLY POISONED INFANT
(mg/100 g)
Tissue
Pentachlorophenol
Kidney
Adrenal
Heart and blood vessel
Fat
Connective tissue
2.8
2.7
2.1
3.4
2.7
Source: Adapted from Armstrong, R. W.,
E. R. Eichner, D. E. Klein, W. F. Barthel,
J. V. Bennett, V. Jonsson, H. Bruce, and
L. E. Loveless, 1969, Pentachlorophenol
Poisoning in a Nursery for Newborn Infants:
II. Epidemiologic and Toxicologic Studies,
J. Pediatr. 75:317-325. Reprinted by per-
mission of the publisher.
-------
350
TABLE D.6.7. AUTOPSY REPORT ON 16-YEAR-OLD PATIENT
FATALLY POISONED WITH PENTACHLOROPHENOL
Macroscopic appearance
Trachea: Slight congestion and edema were present in lower third of
trachea extending into both main bronchi.
Lungs: Slight congestion and edema were present in both lower lobes,
but otherwise nothing significant was seen.
Liver: On the cut surface there were some ill-defined, pale "brown-
ish yellow areas which were scattered throughout the liver tissue;
these were irregular in shape and stood out in contrast to the
darker normal liver tissue. The cut surface had a somewhat cloudy
and glossy appearance.
Microscopic appearance
Heart: Some peculiar degeneration of intravascular leucocytes and
some fragmentation of occasional muscle fibers were found.
Lung: Some passive congestion, patchy collapse, and slight alveolar
hemorrhage were seen.
Analyst report
Pentachlorophenol content: Blood, 5 mg/100 ml; urine, 7 mg/100 ml;
lung, 14.5 mg/100 g; kidney, 9.5 mg/100 g; liver, 6.5 mg/100 g;
brain, 2.0 mg/100 g.
Source: Adapted from Gordon, 1956, Table III, p. 487.
Reprinted by permission of the publisher.
TABLE D.6.8. AUTOPSY FINDINGS FROM THREE PERSONS FATALLY
POISONED WITH PENTACHLOROPHENOL
(mg/100 ml or mg/100 g)
Pentachlorophenol content
Liver
Lung
Kidney
Blood (from lung)
Blood (from liver)
Urine (from bladder)
Stomach
Subject A Subject B
6.2 5.9
7.6
8.4 4.1
9.7
4.6 5.3
2.8
Subject C
5.9
6.3
7.8
Source: Compiled from Blair, 1961.
-------
351
Specific data on the tissue distribution of pentachlorophenol
administered by various routes to experimental animals have been reported
in several studies. Two studies investigated the quantity of pentachloro-
phenol in fat of experimental animals. Larsen et al. (1972) examined the
tissue distribution of [ 1/fC]pentachlorophenol in rats following oral
administration. A low level of pentachlorophenol was found in fat rela-
tive to the concentration in other tissues. Measurable levels of penta-
chlorophenol were found in the fat of female Golden Syrian hamsters up
to 120 hr following oral doses of pentachlorophenol (Hinkle, 1973). The
amount found following the 20 mg/kg exposure was not specified.
Braun and Sauerhoff (1976) recovered 11.7% and 11.2% of a 10 mg/kg
dose in the tissues of two female monkeys 360 hr after administration.
The largest amounts were found in the liver (9.72%) and in the small and
large intestines (7.66%). Other tissues, including brain, fat, muscle,
bone, and remaining soft tissues, contained only 2% to 3.5% of the dose.
In rats, nine days after a single 10 mg/kg dose, 0.44% remained in the
body, with 82% of the residue located in the liver and kidney (Braun et
al., 1977). In a study using one male and one female rat necropsied at
4, 24, 48, 72, and 120 hr after dosing, the highest levels in tissues
were in liver and kidney and the lowest levels were in brain, spleen, and
fat. Except for the liver in female rats and the liver and kidney in
male rats, pentachlorophenol levels were higher in plasma than in organs.
Pentachlorophenol was present in almost every tissue of rabbits 24
hr following a lethal oral dose of a 13.5% solution of pentachlorophenol
(Flickinger, 1971). Deichmann et al. (1942) analyzed the tissues of six
rabbits which died accidentally two to seven days following the beginning
of an experiment in which 3 mg pentachlorophenol per kilogram body weight
was fed. Analyses indicated concentrations of 0.4 to 0.8 mg pentachloro-
phenol per 100 ml of blood, 0.15 to 0.4 mg per 100 g in liver tissue,
and 0 to 0.3 mg per 100 g in kidney tissue. Following repeated cutaneous
applications of pentachlorophenol to rabbits, Deichmann et al. (1942)
found 0.5 to 26 mg/kg in the kidneys, lungs, and liver (Table D.6.9).
Analyses of rabbit tissues 24 hr following oral administration of sodium
pentachlorophenate showed that the largest amounts of pentachlorophenol
(expressed as percent of amount ingested) were located in the stomach
and intestines, muscles, skin, and bones (Table D.6.10). Smaller amounts
were found in the kidney and in the liver and gallbladder combined. How-
ever, when pentachlorophenol levels were expressed as the concentration
in rabbit tissues (i.e., micrograms of pentachlorophenol per gram of
tissue), kidney and liver-gallbladder samples contained the highest
pentachlorophenol concentrations among the tissues analyzed.
Examination of the "percentage of total dose per tissue" data for
mice in Table D.6.11, taken from Jakobson and Yllner (1971), reveals
that the highest levels of pentachlorophenol, following intraperitoneal
injection, were in the stomach, intestines, and liver. Other organs
showed, at most, 2% of the total dose. These investigators noted that
"concentrations" of pentachlorophenol in the tissues (micrograms of
pentachlorophenol per gram organ weight) were highest for the liver and
gallbladder. Very high levels in the gallbladder (three to four times
-------
TABLE D.6.9. CONCENTRATION OF PENTACHLOROPHENOL IN
TISSUES OF RABBITS AFTER CUTANEOUS APPLICATION OF
10 ml OF 1% AQUEOUS SODIUM PENTACHLOROPHENATE FOR
100 CONSECUTIVE DAYS, EXCEPT SUNDAYS
(mg/100 g tissue)
Pentachlorophenol content
Specimen
Urine
Blood
Kidney
Lung
Liver
Brain
Muscle
Rabbits washed 0.5 hr
after application
4.9
0.23
0.14
0.14
0
0
0.06
Rabbits washed 1 hr
after application
6.6
0.45
0.26
0.09
0.05
0
0
TABLE D.6.10. DISTRIBUTION OF PENTACHLOROPHENOL
IN TISSUES OF TWO RABBITS FOLLOWING ORAL DOSES
OF SODIUM PENTACHLOROPHENATE
(% of amount ingested)
Specimen
Urine and feces
Urine
Feces
Stomach and intestine
(wall and contents)
Muscle
Bone
Skin
Blood
Liver and gallbladder
Kidney
Heart, lung, and testes
Central nervous system
Total
Pentachlorophenol
recovered
Rabbit AQ
70.6
6.8
6.4
3.1
2.2
1.9
0.74
0.27
0.17
0.096
92.2
Rabbit Zb
70.3
0.3
3.9
3.6
1.3
3.9
5.7
2.0
0.38
0.32
0.088
91.1
Source: Adapted from Deichmann et al., 1942, Table
4, p. 108. Reprinted by permission of the publisher.
•, Received 94 mg pentachlorophenol.
Received 97 mg pentachlorophenol.
Source: Adapted from Deichmann et al.,
1942, Tables 6 and 7, p. 113. Reprinted by
permission of the publisher.
-------
TABLE D.6.11.
EXCRETION AND DISTRIBUTION OF [ l"C]PENTACHLOROPHENOL IN
MICE AFTER INTRAPERITONEAL INJECTION^
Pentachlorophenol content
Specimen
Urine
0-24 hr
24-48 hr
48-72 hr
72-96 hr
96-168 hr
Feces
0-24 hr
24-96 hr
0-96 hr
24-168 hr
0-168 hr
Liver
Kidney
Lung
Heart
Brain
Stomach (with
contents)
Gallbladder
(with contents)
Intestine (with
contents)
Residue
Total
NO. lb
% of ,
dose "«'«
45
30
5.0
3.4
0.1
7.7
2.2 9
0.09 2
0
0.03 2
0.01 0.1
5.0
98.1
No. 2b
% of ,
dose
45
16
6.1
4.6
4.2
0.8
2.5 10
0.5 8
2.1 21
0.08 60
4.8 8
0.6
87.6
No. 3b
% of ,
dose yS/g
54
12
4.2
2.3
3.8
3.1 26
0.04 1
0
0.5 10
0.06 90
2.2 8
2.0
84.8
No. 4C
% of ,
dose "8'S
60
11
5.8
3.1
1.8
6.5
3.2
1.2 10
0.04 1
0.02 1
0.03 3
0.02 0.5
1.4
93.9
No. 5d
% of ,
dose yg 8
59
15
4.3
1.4
0.9
12
0.4 3
0.01 0.3
0
0.01 1
0
0.1
92.4
OJ
Ol
U)
Doses administered: No. 1, 14.8 mg/kg; No. 2, 18.2 mg/kg; No. 3, 37.2 mg/kg; No. 4, 35.2 mg/kg;
No. 5, 36.8 mg/kg.
^Killed after 96 hr.
^Killed after 7 days.
Killed after 30 days; urine and faces analyzed for first week.
Source: Adapted from Jakobson and Yllner, 1971, Table 1, p. 518. Reprinted by permission of the
publisher.
-------
354
the concentration found in any other tissue) indicate liver metabolism.
In view of the high pentachlorophenol levels found in the gallbladder
of experimental animals, it is suggested that the gallbladder might
serve as an indicator organ in establishing pentachlorophenol exposure.
The data of Larsen et al. (1972) were expressed in a slightly dif-
ferent fashion (Figure D.6.7). The content of pentachlorophenol in the
tissues of rats receiving an oral dose was expressed as the mean percent-
age of dose per gram of tissue. Again, high levels of pentachlorophenol
were found in the liver, stomach, and intestines, and also in the kidneys,
ORNL-OWG 78-10523
Figure D.6.7. Tissue distribution of [l*C]pentachlorophenol and/or
its labeled metabolites 40 hr after oral administration to rats. Source:
Adapted from Larsen et al., 1972, Figure 2, p. 2005. Reprinted by
permission of the publisher.
High levels of pentachlorophenol in the liver, stomach, intestines,
kidneys, and gallbladder can be explained in several ways. The compound
may be present in the kidneys as a result of their function in urinary
excretion. Its presence in the liver may arise from pentachlorophenol
detoxification. ^From whole-body autoradiograms of mice subcutaneously
injected with [14C]pentachlorophenol, Jakobson and Yllner (1971) found:
Four hours after the injection the highest specific activities
were found in the fundus wall of the stomach and in the stomach
and intestinal contents. During 4 hours there was a passage
throughout the gastrointestinal tract A high specific activity
was also recorded for the liver....The blood and kidneys dis-
played moderate activity, the lungs and brain little, if any.
-------
355
After 20 hours the blackening corresponding to the wall of
the stomach fundus was considerably weaker but the contents of
the stomach, and especially the intestines, still caused marked
blackening. A considerable amount of activity was collected
in the liver and moderate amounts were still recorded in the
blood and kidneys.
After 100 hours the distribution was largely the same as
after 20 hours. The strongest blackening was registered for
the intestinal contents and the liver. In the kidneys it was
moderate....
A number of organic compounds, most of them basic, are
secreted by gastric juice....The high specific activity in
the wall of the stomach fundus and the stomach contents
evident in the auto radiograms shows that PCP is also secreted
in this way....The high specific activity of the gall bladder
and its contents, however, shows that biliary secretion is also
important in the metabolism of PCP. The excretion of PCP
and its metabolites thus occurs via the kidneys and by the
processes of gastric and biliary secretion; the greater part
being passed in the urine.
The findings of Deichmann et al. (1942) are consistent with this
hypothesis even though the liver and gallbladder were analyzed together.
Larsen et al. (1972) demonstrated activity in the liver but could not
analyze gallbladder tissue because rats lack this organ. The transport
and distribution scheme proposed by Jakobson and Yllner (1971) (Figure
D.6.8) thus appears consistent with present information. A modified
scheme (Figure D.6.9) includes the possibility that pentachlorophenol is
bound to serum proteins in the blood and the evidence for gastric and
biliary secretion (Casarett et al., 1969). If entry into the blood from
the skin and lungs were included, this diagram would seem to account for
ORNL-CA3 78-'C52<=
URINE
FECES
Figure D.6.8. Turnover of pentachlorophenol and/or its metabolites
in the mouse. Source: Adapted from Jakobson and Yllner, 1971, Fxgure ,
p. 523. Reprinted by permission of the publisher.
-------
356
OR1L-D*G '8-1O525
RICLE
STOMACH
GALLBLADDER
\
BLOOD "^"SERUM PROTEIN
INTESTINES
URINE
FECES
Figure D.6.9. Proposed turnover of pentachlorophenol and/or its
metabolites in mammals.
all transport mechanisms in the mammalian system with the possible ex-
ception of placental transfer. The following statements summarize the
transport and distribution of pentachlorophenol in humans and experimen-
tal animals:
1. Pentachlorophenol is distributed in some quantity throughout the
body tissues.
2. Highest tissue levels are found in the liver, kidney, and blood.
3. There is evidence of enterohepatic circulation which may prolong the
elimination of a small amount of absorbed pentachlorophenol.
4. There is no evidence to suggest a significant long-term accumulation
in body fat of mammals such as that which occurs with some chlorinated
hydrocarbon chemicals.
D.6.1.2.3 Placental Transfer — Transfer of pentachlorophenol across
the placenta has not been adequately studied, and complete data have not
been reported. Investigations by Hinkle (1973) indicated that penta-
chlorophenol can cross the placental barrier and enter the fetus. Oral
doses of pentachlorophenol ranging from 1.25 to 20 mg/kg body weight were
administered daily to Golden Syrian hamsters. Samples of maternal blood
and fat and entire fetuses were analyzed. According to Hinkle (1973),
"There was close correlation between the concentrations of PCP recovered
from the maternal blood and the fetuses. The highest measured concentra-
tions in the blood, fat and fetuses occurred within 3 hr following the
last administered oral dose. Concentrations in fat persisted in measure-
able amounts up to 120 hr following the last oral dosing and exceeded the
blood and fetal concentrations at that time." Unfortunately, quantita-
tive data were not given.
Larsen et al. (1975) found a negligible placental transfer of penta-
chlorophenol in rats. Radiolabeled pentachlorophenol was administered
orally in a solution of olive oil at a dose of 68 mg/kg body weight,
which is approximately 75% of the reported LD50 (Figure D.6.10). The
authors believed that the amounts found in the placentas probably
-------
357
1.2
1.0
O)
3
in
O
o>
-g 0.8
=3 0.6
CO
to
0.4
Q.
O
o:
o
0.2
LJ
CL
ORNL-DWG 78-10526
O BLOOD SERUM
D PLACENTA
V FETUS
2 4 8 12 16 24
TIME AFTER DOSE (hr)
32
Figure D.6.10. [14C]Pentachlorophenol and/or its metabolites in
tissues after an oral dose to pregnant rats on day 15 of gestation.
Source: Adapted from Larsen et al. , 1975, Figure 1, p. 125. Reprinted
by courtesy of Marcel Dekker, Inc.
resulted largely from the blood content. Figure D.6.10 shows that the
pentachlorophenol levels of the fetuses remained very low throughout the
experiment. It is difficult to assess the validity of the conflicting
reports by Hinkle (1973) and Larsen et al. (1975). It is not clear in
the Hinkle (1973) study whether or not placental tissue was included in
the analysis under the category of entire fetuses. If it were included,
contamination of fetal tissue by placental blood could explain the fetal
levels of pentachlorophenol.
D.6.1.3 Biotransformation
Table D.6.12 summarizes biotransformation data and pentachloro-
phenol compounds found in the urine of experimental animals and humans.
Pentachlorophenol is principally eliminated in the urine except for very
high oral doses, in which case significant amounts appear in the feces.
Amounts of unchanged pentachlorophenol found in urine range from 100%
for the rhesus monkey down to 40% in the mouse. Other compounds include
tetrachlorohydroquinone and pentachlorophenol or tetrachlorohydroquinone
-------
TABLE D.6.12. PENTACHLOROPHENOL BIOTRANSFORMAT10N IN MAMMALS
Species
Sex
Dose
(mg/kg)
Route
Peak
blood
levela
(ppm)
Time
Co peak
levela
(hr)
Plasma
half-
life0
(hr)
Excretion in
urine and feces
Man
Monkey Male
Rat
0.1
10
Female 10
25
Male 10
Female 10
Oral
Oral
Intraperi-
toneal
Oral
Oral
0.248
10-30
10-30
NR
45
45
NR
4-6
4-6
30.2
12-24 72
12-24 83
NR
17 (a)
40 (B)
13 (a)
33 (6)
Peak at 42 hr; half-life
for pentachlorophenol
33 hr; half-life for
pentachlorophenol glu-
curonide 12.7 hr
Urine half-life 41 hr
Urine half-life 92 hr -
360 hr after single
dose; 70% in urine,
18% in feces, and 11%
in tissues
70% in urine at 24 hr
80% in urine, 19% in feces
78% in urine, 19% in feces
Metabolites found
Source
74% in urine as pentachlo-
rophenol, 12Z in urine
as pentachlorophenol
glucuronide, 4% in feces
as pentachlorophenol
and pentachlorophenol
glucuronide
In urine as unchanged
pentachlorophenol, no
metabolites
43% as unchanged penta-
chlorophenol, 5X as
tetrachlorohydroquinone,
38% as tetrachlorohydro-
quinone conjugate, and
14% as pentachlorophenol
conjugate
Braun, Blau, and
Chcnoweth, 1978
Braun and Sauerhoff,
1976
Braun and Sauerhoff,
1976
Ahlborg, Lindgren,
and Mercier, 1974
Braun et al., 1977
Braun et al., 1977
OO
(continued)
-------
TABLE D.6.12 (continued)
Species Sex , ^f . Route
v (mg/kg)
Male 100 Oral
Peak
blood
level12
(ppm)
Time
to peak
level0
(hr)
Plasma
half-
life0
(hr)
13 (a)
121 (6)
Excretion in
urine and feces
72% in urine, 24X in feces
Metabolites found
Urine: 75% as pentachlo-
rophenol, 9% as penta-
Source
Braun et al. , 1977
Female 100
Mouse 25
Oral
NR
NR
15-37
Intraperi-
toneal or
subcutaneous
NR
NR
27
NR
NR
(6)
54% in urine, 43% in feces
70% in urino at 24 hr
NR
722-83% excreted in urine
in four days; about half
in 24 hr; 5%-72 in Tocos
chlorophenol glucuronide,
16% as tetrachlorohydro-
quinone; half-lives of
24 hr for pentachloro-
phenol, 25 hr for penta-
chlorophenol glucuronide,
and 32 hr for tetrachlo-
rohydroquinone
See data above; urine was
pooled.
41% as unchanged ptntachlo-
rophenol, 24% as tetra-
chlorohydroquinone, 22%
as tetrachlorohydroqui-
none conjugate, and 13%
as pentnchlorophenol
con j uga te
About 45% as unchanged
pentachlorophcnol, 142!
as pentnchlorophenol
conjugate, and 40% as
te t rachlorohydroquinone
Braun et al.
1977
Ahlborg, Lindgren,
and Mercier, 1974
Jakobson and
Yllner, 1971
U)
Ur
vo
NR — Not reported.
-------
360
conjugates. Some studies have found the conjugates to include glucuro-
nides; others have not identified the conjugates.
The earliest investigation of pentachlorophenol metabolism was re-
ported by Deichmann et al. (1942). The rate of destruction of penta-
chlorophenol was monitored in rats and rabbits. A colorimetric method
of analysis based on the reaction of pentachlorophenol with fuming nitric
acid following steam distillation of acidified specimens was used. Fol-
lowing oral administration of sodium pentachlorophenate to rabbits, 50%
to 75% of the ingested pentachlorophenol was excreted in the urine and
feces over a 24-hr period (Figure D.6.11). Analysis of pentachlorophenol
in the carcasses revealed that 10% of the ingested pentachlorophenol was
unaccounted for and presumably was metabolized. Rats given an intra-
peritoneal injection of pentachlorophenol excreted approximately 12.5%
over a 24-hr period; analysis of carcasses showed that 40% of the in-
jected pentachlorophenol had been metabolized (Table D.6.13). In other
experiments, Deichmann et al. (1942) found that detoxification through
conjugation to sulfuric or glucuronic acid did not occur; no other metab-
olites were detected.
Jakobson and Yllner (1971) have shown that pentachlorophenol can be
detoxified in mice by conjugation and metabolism. Labeled compounds in
S 60 -
UJ
z
o
UJ
I
a.
O
(r
O
X
o
z
UJ
Q.
ORNL-DWG 78-21O82
— 3
1
5
i
o
tu
— 2
I—I L_l I I I i i i
O
LU
Q.
O
a:
o
o
<
UJ
Q.
Figure D.6.11. Excretion of pentachlorophenol by rabbits after
oral administration of sodium pentachlorophenate. Source: Compiled
from Deichmann et al., 1942, Table 8, p. 114.
-------
361
TABLE D.6.13. RECOVERY OF PENTACHLOROPHENOL IN THE CARCASSES
AND EXCRETA OF RATS FOLLOWING A SINGLE INTRAPERITONEAL DOSE
OF 2.4 mg PENTACHLOROPHENOL PER ANIMAL
Time animal killed ,„ Pentachlorophenol
after treatment U °f amount injected)
In excreta In carcass Metabolized
0
3
12
24
48
72
96
120
144
0
7.5
6.6
13
17
13
8.3
9.5
12
100
83
68
47
23
18
15
13
13
0
10
25
41
61
68
77
78
75
Source: Adapted from Deichmann et al., 1942, Table 9,
p. 115. Reprinted by permission of the publisher.
urine, collected 0 to 24 hr after intraperitoneal injection of [lilC]penta-
chlorophenol were identified using an isotope dilution technique before
and after paper chromatographic separcition. These investigators found
that about 60% of the injected isotope activity was excreted in the urine
in 24 hr. About 30% of the injected pentachlorophenol appeared in the
urine as unchanged pentachlorophenol (Table D.6.14). Acid hydrolysis of
the urine and subsequent analysis yielded an additional 8% of the total
dose, which apparently resulted from pentachlorophenol conjugates; the
nature of these conjugates was not determined. Approximately 21% of the
injected iltC activity consisted of 1AC-labeled tetrachlorohydroquinone;
this compound was possibly conjugated in the urine. Because the sample
was insufficient, only one determination of tetrachlorohydroquinone in
the urine was made prior to hydrolysis, and the extent of tetrachloro-
hydroquinone conjugation could not be assessed. The presence of penta-
chlorophenol and tetrachlorohydroquinone in the urine was confirmed by
paper chromatography utilizing two different solvent systems. From the
recovery values of 1AC activity, it was apparent that pentachlorophenol
and its conjugates and tetrachlorohydroquinone and its conjugates ac-
counted for >97% of the urinary activity excreted. The findings of
Jakobson and Yllner (1971) are consistent with the data for rats report-
ed by Deichmann et al. (1942). In summary, degradation of pentachloro
phenol 24 hr following administration to rats and mice was 40% and JU7.
-------
TABLE D.6.14. CARBON-14 ACTIVITY IN URINE COLLECTED 0 TO 24 hr AFTER INTRAPERITONEAL
INJECTION OF ['''C] PENTACHLOROPHENOL IN MICE
Dose
(mg/kg)
36. 3a
17. 0*
7.9*
Pentachlorophenol
% of dose . ° it,,
urinary (
29 50
30 54
/^ ^"*
26 54
Pentachlorophenol
conjugates
] % of dose 7° °£ lt,n
urinary C
9 16
7 12
Tetrachlorohydroquinone
and conjugates Total urinary
u cictivzuy
-------
363
respectively. In the rabbit, 8% of the administered dose was degraded
in 24 hr. Intraperitoneal injection was the route of uptake for both
the rat and the mouse; the different rates of degradation noted in the
rabbit following oral administration could be due either to species
differences or to the route of entry of the compound.
Similarly, Ahlborg, Lindgren, and Mercier (1974) gave mice and rats
intraperitoneal doses of [ 1Z
-------
TABLE D.6.15. CARBON-14 ACTIVITY IN URINE OF RATS AND MICE RECEIVING 10 TO 25 mg/kg
PENTACHLOROPHENOL IN A SINGLE INTRAPERITONEAL DOSE
Animal
Rat
Mouse
Treatment
of urine
None
HC1 at 100°C
None
HC1 at 100°C
As pentachlorophenol
43
57
41
54
14C activity in urine (%)
As tetrachlorohydroquinone
5
43
24
46
As pentachlorophenol and
tetrachlorohydroquinone
conjugates
52
35
Source: Adapted from Ahlborg, Lindgren, and Mercier, 1974, Table 2, p. 277. Reprinted by permis-
sion of the publisher.
-------
365
orally; small amounts of chloroanil, a compound closely related to tetra-
chlorohydroquinone, were also found. The acidic metabolite was character-
ized as pentachlorophenyl B-glucuronide, but it decomposes at high
temperatures to pentachlorophenol; the conditions for mass spectrometry
provide sufficiently high temperatures for this transformation. Treat-
ment of the metabolite with dilute hydrochloric acid yielded pentachloro-
phenol, glucuronic acid, and glucuronolactone; it also was hydrolyzed by
the action of 3-glucosidase. This substance was also a major metabolite
in the urine of rats dosed subcutaneously with sodium pentachlorophenate.
Chloranil and pentachlorophenyl 3-glucuronide were incorporated into a
proposed metabolic pathway for pentachlorophenol in mammals (Figure
D.6.12). This is the only study which specifically reported the conjuga-
tion of pentachlorophenol to glucuronic acid in experimental animals.
A metabolic pathway similar to that proposed by Tashiro et al. (1970)
was outlined by Jakobson and Yllner (1971) (Figure D.6.13). In some
ways, all of the data reported appear to be consistent with each of these
pathways. In Figure D.6.14, this information is combined into a single
integrated metabolic pathway for pentachlorophenol in mammals. Species
differences must be kept in mind.
Substantial amounts of pentachlorophenol are found in the liver fol-
lowing different routes of administration. Based on the known role of
the liver in detoxification of foreign substances, it is apparent that
metabolic breakdown may take place. No studies were found in which the
bile duct was cannulated and the pentachlorophenol metabolism in the
liver was characterized. However, the work of Jakobson and Yllner (1971)
points out both the mobility of pentachlorophenol in body tissues and in
the biliary secretion. They injected [ 1AC]pentachlorophenol into mice
and found high activity in the stomach fundus, stomach contents, and
gallbladder. Pentachlorophenol may also be secreted in the gastric juice
(Jakobson and Yllner, 1971). Braun et al. (1977) reported that most of
the pentachlorophenol remaining in the rat body was found in the liver
eight days after a single 10 mg/kg dose. Braun and Sauerhoff (1976)
ORHL—DWG 78-10527
Cl Cl
HO
OH
PENTACHLOROPHENOL
CONJUGATE
Cl Cl
EXCRETION
Figure D.6.12. Proposed metabolic pathway of pentachlorophenol in
mammals. Source: Adapted from Tashiro et al., 1970, Figure 5, p. 1M>
Reprinted by permission of the publisher.
-------
366
PENTACHLOROPHENOL
CONJUGATE
ORNL-DWG 78-10528
COOH
TETRACHLOROHYDROQUINONE
TETRACHLOROHYOROQUINONE
CONJUGATE
Figure D.6.13. Proposed metabolic pathway of pentachlorophenol in
mice. Source: Adapted from Jakobson and Yllner, 1971, Figure 2, p. 522.
Reprinted by permission of the publisher.
ORNL-DWG 78-10529
PENTACHLOROPHENOL
I
Cl
/
/ OH
TETRACHLOROHYDROQUINONE
u
Cl \
PENTACHLOROPHENOL I
CONJUGATE . |
\ ' /
\J/x
EXCRETION
CHLORANIL ^ TETRACHLOROHYOROQUINONE
_ -^ CONJUGATE
COOH
HO
VOH
OH
Figure D.6.14. Proposed integrated metabolic pathway of pentachloro-
phenol in mammals.
-------
367
demonstrated that the rhesus monkey continues to eliminate some penta-
chlorophenol in the feces after the initial bolus would have been elim-
inated; this is further evidence for biliary excretion and enterohepatic
circulation. Enterohepatic circulation would contribute to a prolonged
half-life of trace-level residues.
D.6.1.4 Elimination
The primary mode of pentachlorophenol excretion appears to be through
the urine. Although initial elimination may be very rapid, it has been
shown that following exposure to pentachlorophenol a return to background
levels may take as much as a month, as in the case of an individual in
Hawaii who was exposed while cleaning a paint brush in a solution con-
taminated with pentachlorophenol (Bevenue, Haley, and Klemmer, 1967)
(Table D.6.2). In evaluating the data, these authors stated, "The penta-
chlorophenol residue in the urine of individuals not knowingly occupation-
ally exposed (201 samplings) had a mean value of 23 pbb. It is noted...
from the data... that about one month was required for the pentachloro-
phenol concentration in the affected individual's urine to decrease to
the average amount observed in random samplings of the local male popu-
lation not occupationally exposed."
Two volunteers were exposed to pentachlorophenol by inhalation
(Casarett et al. , 1969). Urinary concentrations of pentachlorophenol
(normalized to 100 mg of creatinine) were monitored and plotted as the
midpoint of the interval during which the urine was collected. The rate
of excretion during the first 10 to 24 hr was less than that beyond 24
hr. The data are expressed differently in Figure D.6.5; data from both
subjects were sufficiently similar to allow a single line to be drawn
through the plotted points. The early rate of excretion indicates an
excretion half-life between 40 and 50 hr, but the rate of excretion after
24 hr can be represented by a half-life of approximately 10 hr.
Braun, Blau, and Chenoweth (1978) found the pentachlorophenol half-
life in plasma to be 30.2 ± 4.0 hr. The half-lives for elimination of
pentachlorophenol and pentachlorophenol glucuronide from urine were 33.1
± 5.4 hr and 12.7 ± 5.4 hr respectively. The dynamics of elimination in
humans were described as a one-compartment, open-system model with first-
order absorption, enterohepatic circulation, and first-order elimination.
Bevenue et al. (1967) conducted an extensive survey as part of a
community pesticide program in Hawaii. Data on levels of pentachloro-
phenol in urine of occupationally and nonoccupationally exposed persons
were collected. In Hawaii, pentachlorophenol is used extensively for
the treatment of wood products to control termites and has been used as
a preemergence herbicide in pineapple and sugar cane fields. It is per-
haps not surprising, therefore, to find a substantial level of penta-
chlorophenol in the urine and blood of nonoccupationally exposed Hawanans
(Section D.6.2.4.2). Sequential urinary levels in occupationally exposed
persons were examined to identify exposure probabilities among workers and
individual variation in excretion patterns. Pairings of samples (one
sample taken immediately following exposure) from the sequential urinary
-------
368
level determinations were used to calculate a mean daily rate of decre-
ment in urinary pentachlorophenol (Figure D.6.15). The log of the rate
of decrease of urinary pentachlorophenol was plotted against time over
which the decrement occurred. Bevenue et al. (1967) stated, "Although a
smooth curve has been dram, two single straight lines can also be drawn
because the data can as readily be represented as a combination of two
exponential functions. This suggests the possibility of two different
excretion rates."
Apparently, a partially independent relationship exists between the
amount of pentachlorophenol in the initial sample and the rate of decrease
in the urine (Figure D.6.16). If one assumes that the rate of excretion
is related to the total body dose or burden, the amount and rate of penta-
chlorophenol excreted apparently increases as the body content increases.
Furthermore, it appears that the rate of excretion is higher when the body
burden is sufficiently high to result in an excretion level greater than
3 to 5 mg/liter in the "initial" sample, again implying the possibility
of more than one excretion rate. Bevenue et al. (1967) emphasized that
more data are necessary to support the suspicion of a "threshold" above
which there is a higher excretion rate and below which there is a slower
rate. Caution must be observed in interpreting these data because as
the authors stated, "If one could assume that the time between samples
was the interval following a single exposure, the conclusion that there
are two rates of excretion might be justified. However, there is no way
to eliminate the possibility that intermittent exposures had occurred in
most of the individuals represented...." Such exposures could explain
at least part of the apparent change of rate and might even be the entire
explanation.
100
ORNL-DWG 78-10534
tt
1
K
UJ
O
< -i
UJ X
tc "
UJ
Q_
10
0 30 60 90
TIME BETWEEN SAMPLES (doys)
120
Figure D.6.15. Change in urinary pentachlorophenol with time for
occupationally exposed people. Source: Adapted from Bevenue et al.,
1967, Figure 2, p. 328. Reprinted by permission of the publisher.
-------
369
70
' 60
o
o
£! 50
UJ
K
(J
X
Ul
>• 40
o
<
UJ
s
_
I
o
30
20
«>
ORNL-OWG 78-2(083
.J>~-A-^i—A—i-
O CUMULATIVE MEAN
A MEAN
4 6
TIME (doys)
20 o
o
UJ
(-
UJ
o:
o
X
UJ
10
2
<
Ul
10
Figure D.6.16. Decrease in urinary pentachlorophenol with time for
occupationally exposed people. Source: Adapted from Bevenue et al. ,
1967, Figure 3, p. 328. Reprinted by permission of the publisher.
Casarett et al. (1969) also conducted an epidemiological study of
the blood and urine concentrations of occupationally and nonoccupation-
ally exposed persons in Hawaii. Although it is difficult to draw con-
clusions from this type of investigation because the total body dose or
body burden was unknown, some interesting inferences were drawn. Figure
D.6.2 suggests that the ratio of pentachlorophenol in blood to that in
urine is between 1.5 and 2.5, but considerable variations appear in
individual measurements. Although this ratio is similar to that found
in some acute intoxications (Blair, 1961), other reports of acute intoxi-
cations gave higher concentrations in the urine than in the blood (Gordon,
1956; Bergner, Constantinidis, and Martin, 1965).
This blood to urine ratio is in marked contrast to the findings in
experimental animals. When single doses of pentachlorophenol are adminis-
tered to experimental animals, urinary levels of pentachlorophenol are
invariably higher than blood levels (Machle, Deichmann, and Thomas, 1943).
Casarett et al. (1969) also reported that in preliminary animal studies
with single doses, higher concentrations of pentachlorophenol are found
in urine than in blood. This suggests that if a species difference does
not exist, a kinetic difference exists between single and chronic exposures.
-------
370
Larsen et al. (1972) suggested a two-component urinary excretion of
pentachlorophenol in rats following oral administration (Figure D.6.17).
In fact, the curve was resolved into two components by fitting the data
into an 'exponential equation (terms not explained):
The first component had a half-life of 10 hr, and the second component
had a half-life of 102 days. This study was criticized by Braun et al.
(1977). They stated, "These values were obtained from a sigma-minus
plot by subtracting the cumulative amount excreted in the urine from the
total dose. This approach may cause gross errors in estimating elimina-
tion rates unless the total recovery approaches 100% of the dose ---- Since
the total recovery of the dose was not reported in the communication by
Larsen and co-workers cited above, the accuracy of the reported 102-day
half -life for elimination is questionable."
Braun et al. (1977) described the pharmacokinetics of pentachloro-
phenol in rats given single oral doses of [1AC] pentachlorophenol. Table
D.6.16 summarizes the results. A two-compartment open-system model was
necessary to describe the data for males given 10 or 100 mg/kg and for
females given 10 mg/kg. The results showed a rapid elimination of penta-
chlorophenol in the urine. Only 0.4% of the dose remained in the body
after nine days. This is in contrast to the data of Larsen et al. (1972),
who reported 30% of the dose remaining in the body after ten days. The
Larsen study did not report total recovery and may have ignored fecal
ORNL-DWG 78-21084
0 80 160 340 320
DAILY URINARY EXCRETION (/ig/liter)
Figure D.6.17. Excretion of orally administered [14C]pentachloro-
phenol by rats. Source: Compiled from Larsen et al., 1972, Table I,
p. 2004.
-------
371
TABLE D.6.16. PHARMACOKINETICS OF PENTACHLOROPHENOL IN RATS
Sex
Male
Female
Dose
(mg/kg)
10
100
10
100
Pentachlorophenol
excreted in
8-9 days (%)
Urine Feces
80.1 18.8
72 24
78.13 19.3
54 43
Half-life
Rapid
phase
17
13
13,
27b
(hr)
Slower
phase
40
121
33
NR
Volume of
distribution
(ml/kg)
136
NRa
127
NR
,NR — Not reported.
Data were described by a one-compartment open model.
Source: Compiled from Braun et al., 1977.
excretion in the calculations. As pointed out above, the 102-day com-
ponent could have resulted from the methods used.
As far as can be determined, pentachlorophenol and its sodium salt
are excreted with the same kinetics, but some evidence suggests that
excretion rates may depend on the route of administration of the com-
pound. Work by Ahlborg, Lindgren, and Mercier (1974) indicates that in
rats and mice excretion is higher for intraperitoneal administration of
pentachlorophenol than for oral administration (Figure D.6.18). From
this research, excretion appears to be more rapid in rats than mice.
In general, similar urinary excretion rates are found for rats, rabbits,
and mice. Approximately 50% of the administered pentachlorophenol is
excreted in the urine in 24 hr and 70% to 85% in four days (Deichmann
et al., 1942; Jakobson and Yllner, 1971; Larsen et al. , 1972).
The monkey eliminates pentachlorophenol somewhat more slowly than
other animals studied. In an experiment by Braun and Sauerhoff (1976),
two monkeys were administered a single dose of 10 mg/kg pentachlorophenol.
After 360 hr, 70% of the dose was eliminated in the urine, 18% in the
feces, and 11% remained in the carcass. Excretion by the kidney was a
first-order process characterized by half-lives of 40.8 hr (male) and
92.4 hr (female). Plasma levels decreased by a first-order process with
half-lives of 72 hr (male) and 83.5 hr (female).
Although the primary route of pentachlorophenol elimination appears
to be urinary, fecal excretion also plays a role. Values ranging from
4% of the injected dose in the rabbit (Deichmann et al., Wi) to jo. .
in rats (Larsen et al., 1972) over a ten-day period have ^en reported.
However, quantitative fecal excretion rates were not readily found in
the literature.
-------
372
400
- 50
UJ _.
Q- ?
ORNL-DWG 78-10530
O RATS
V MICE
24
-O O
ORAL
INTRAPERITONEAL
48
TIME (M
72
96
Figure D.6.18. Cumulative excretion of [ 1Z*C] pentachlorophenol in
the urine of rats and mice after a single oral or intraperitoneal dose.
Source: Adapted from Ahlborg, Lindgren, and Mercier, 1974, Figure 1,
p. 276. Reprinted by permission of the publisher.
It is difficult to draw conclusions concerning the elimination of
pentachlorophenol from most of the reported data on urinary excretion
in humans for the following reasons: (1) the exposures were accidental
or occupational with the quantity unknown, (2) excretion via the fecal
route was not determined, and (3) the reports do not account for continued
background exposure. There is some speculation that there may be some
long-term tissue storage of pentachlorophenol. This hypothesis results
from consideration of the long-term storage of chlorinated hydrocarbon
insecticides such as DDT and dieldrin in fat; the inference is made that
pentachlorophenol may act accordingly. Another factor generating this
speculation is data from occupationally exposed individuals whose urine
or blood pentachlorophenol levels do not return to zero. Control popula-
tions studied also have had low levels in blood and urine; thus, it is
possible that continuous low-level exposure may account for these findings.
In future studies on the kinetics of pentachlorophenol the following
precautions should be observed:
1.
2.
3.
If nonradiotracer techniques are used, background pentachlorophenol
levels in water and diet should be monitored, especially in studies
dealing with parts-per-billion residue levels.
Studies should account for fecal excretion, regardless of the route
of exposure.
Some plasma protein binding with a specific high affinity, as sug-
gested by Braun et al. (1977), could account for a long-term, low-
level residue in blood.
-------
373
D.6.2 EFFECTS
D.6.2.1 Physiological or Biochemical Role
No normal physiological or biochemical role of pentachlorophenol in
humans has been documented. In the absence of a physiological require-
ment, deficiency syndromes do not occur. Concentrations of pentachloro-
phenol in tissues and organs reflect exposure of the individual to the
compound in some manner.
D.6.2.2 Toxicity
D.6.2.2.1 Mechanisms of Action — Pentachlorophenol is a broad-
spectrum biocide. Weinbach (1957) proposed that the mechanism of penta-
chlorophenol toxicity was either nonspecific, involving a number of
unrelated metabolic processes, or — the preferred explanation — involved
a basic mechanism common to many forms of life. The primary effect of
pentachlorophenol on organisms is likely the uncoupling of oxidative
phosphorylation, thereby short-circuiting the energy balance.
On the molecular level, the major effects of pentachlorophenol
appear to be on mitochondria and their associated energy systems. The
in vitro effects of pentachlorophenol on mammalian or molluscan mito-
chondria include uncoupling of oxidative phosphorylation, inhibition of
mitochondrial and myosin adenosine triphosphatase (ATPase), inhibition
of glycolytic phosphorylation, inactivation of respiratory enzymes, and
gross damage to mitochondrial structure (Weinbach, 1957). The effects of
pentachlorophenol on snail tissue and rat liver at various concentrations
in vitro and the possible physiological significance are outlined in
Table D.6.17. The systemic effects of pentachlorophenol intoxication can
be quite drastic, including changes in and degeneration of many of the
vital organs (Section D.6.2.2.2). General systemic effects of pentachloro-
phenol can be explained on the basis of the basic biochemical alterations
described by Weinbach (1957). Table D.6.17 shows that the three ranges of
pentachlorophenol concentrations have different effects at the biochemical
level. Low concentrations from 10~6 to 10"" M uncouple oxidative phos-
phorylation and result in an increase in respiration. Values of 10 M
and higher drastically curtail glycolytic phosphorylation and result in
inactivation of the respiratory enzymes with a drastic reduction in res-
piration. Intermediate values from 10~* to 10~3 M inhibit the action of
mitochondrial ATPase and myosin ATPase. Investigations by Mitsuda,
Murakami, and Kawai (1963) confirmed these findings and indicated that at
intermediate levels of pentachlorophenol, respiration is neither stimulated
nor inhibited. The actual process involved in oxidative phosphorylation
remains a subject of controversy; thus, a detailed discussion of the
action of pentachlorophenol as an uncoupler is not attempted. It is
possible, however, from the data available to speculate on the action ot
pentachlorophenol on oxidative phosphorylation.
Weinbach and Garbus (1965) presented convincing evidence that penta-
chlorophenol binds preferentially to mitochondrial protein, thereby in-
ducing changes in the enzymes involved with oxidative phosphorylation ana
-------
374
TABLE D.6.17.
EFFECTS OF VARIOUS CONCENTRATIONS OF PENTACHLOROPHENOL
ON SNAIL TISSUE AND RAT LIVER IN VITRO
Concentration of
pentachloropheno1
(AO
Effect
Possible
physiological
significance
10'6 to 10
10-" to 10
10"3 and higher
Uncoupling of oxidative
phosphorylation
Inhibition of mitochondrial
ATPase
Inhibition of myosin ATPase
Inhibition of glycolytic
phosphorylation
Inactivation of respiratory
enzymes
Gross damage to mitochon-
drial structure
Interference with cellular
aerobic exergonic
processes
Unknown
Interference with phosphate
transfer (and muscle
function?)
Rapid death of the cell and
of the organism
Source: Adapted from Weinbach, 1957,. Table 3, p. 396. Reprinted by
permission of the publisher.
preventing the binding or rebinding of functional factors essential for
bioenergetic processes. They found that the insoluble protein residue
which remained after extraction of lipids and water-soluble components
from mitochondria had an affinity for pentachlorophenol equal to or great-
er than that of intact mitochondria. Weinbach and Garbus (1965) suggested
that the interaction of pentachlorophenol with the protein moiety of intact
mitochondria is responsible for its uncoupling action.
Further evidence regarding the binding of pentachlorophenol to
enzymes was developed by Bowen, Martin, and Jacobus (1965), who utilized
actomyosin. Because pentachlorophenol is known to interfere with the
enzymatic activity of myosin ATPase, it is reasonable to assume that
pentachlorophenol binding plays a role in enzyme inhibition. Acetylation
of actomyosin greatly reduced the binding of pentachlorophenol to the
muscle protein, suggesting that the amino groups of the protein are the
sites of pentachlorophenol binding, probably to lysine and arginine
residues.
Hanstein and Hatefi (1974) provided additional support for the pro-
posal that pentachlorophenol binding to mitochondrial proteins is neces-
sary for its uncoupling action. Mitochondrial uncoupler sites were
located and characterized by using an uncoupler capable of photoaffinity
labeling in the membrane of the mitochondria. Preliminary results in-
dicated that the protein involved in uncoupling had a molecular weight
of 20,000 to 30,000. 2,4-Dinitrophenol and sodium azide, two other potent
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375
uncouplers, also are apparently bound to the same site as pentachlorophenol.
Thus, sound evidence exists for 'the binding of pentachlorophenol to a mito-
chondrial protein as a requirement for the uncoupling activity of the
substance.
A conflicting view on the role of pentachlorophenol binding to pro-
teins was presented by Stockdale and Selwyn (1971). The kinetics of
inhibition of several enzymes by pentachlorophenol was determined and
then compared with the kinetics involved in the uncoupling action of
pentachlorophenol. They found that pentachlorophenol inhibits several
enzymes at concentrations similar to those producing inhibition of solu-
ble mitochondrial ATPase (Table D.6.18). According to Stockdale and
Selwyn (1971), "The observations reported here suggest that sensitivity
to inhibition by low concentrations of phenols is a fairly general prop-
erty of kinases and dehydrogenases. The effects of phenols on the
ATPase share several features with their effects on other enzymes but
none with their effects as uncouplers. No evidence has been found to
support the view that the effects on the ATPase are related to uncou-
pling. For the same reasons these observations do not support the less
TABLE D.6.18. ENZYME INHIBITION BY PENTACHLOROPHENOL
Effect of pentachlorophenol
Enzyme r
Log 1/Jso a Log 1/C50 Log l/Cm
Hexokinase 2.98
Pyruvate kinase 3.46
Creatine phosphokinase 2.70
Phosphofructokinase 3.90
Lactate dehydrogenase 3.70
Malate dehydrogenase 3.96
Alcohol dehydrogenase 3.89
Glyoxalate reductase 3.09
Catalase <1>52^
Acid phosphatase <1.70"
ATPase 3.87 4.82
— Pentachlorophenol concentration producing 50%
inhibition, expressed in molarity.
^C*50 — Pentachlorophenol concentration required to inhibit
the enzyme to a rate equal to 50% of the basal rate.
°Crn — Pentachlorophenol concentration required to produce
maximal stimulation of isolated enzyme.
<^No significant inhibition observed at this concentration.
Source: Adapted from Stockdale and Selwyn, 1971, Table 1,
p. 418. Reprinted by permission of the publisher.
-------
376
specific suggestion of Weinbach and Garbus (1965) that the interaction
of uncouplers with proteins is related to their uncoupling activity."
Stockdale and Selwyn (1971) stated that pentachlorophenol has a dual
effect on mitochondria, which includes a discrete action in uncoupling
oxidative phosphorylation as distinct from the action of pentachloro-
phenol in inactivating mitochondrial ATPase as well as other enzymes in
the cell. Evidence was presented to justify the belief that pentachloro-
phenol may bind to the active site of the enzyme which normally binds
the adenine group in the usual substrate.
It is difficult to reconcile the data of Weinbach and Garbus (1965)
with that of Stockdale and Selwyn (1971) unless one proposes a dual
action for pentachlorophenol in mitochondria. This dual action includes
binding of pentachlorophenol at low concentrations to the protein in-
volved in oxidative phosphorylation. At higher concentrations, however,
pentachlorophenol binds to other enzymes in the cell, including mitochon-
drial ATPase and the respiratory enzymes. This second action might well
involve competitive or noncompetitive binding of pentachlorophenol to
the active site of the enzymes, thereby displacing the adenine moiety
present in the normal substrate. Some caution should be used in inter-
preting the data of Stockdale and Selwyn (1971) , who used purified en-
zymes in their assay system in contrast to other investigators utilizing
intact mitochondria. Some of the conflicting findings may result from
permeability effects in the intact mitochondria.
At high levels of pentachlorophenol other indirect effects are
possible (Ishak, Sharaf, and Mohamed, 1972). The inhibition of succi-
nate oxidation, which is frequently seen in the presence of uncouplers,
may well be due to the accumulation of oxaloacetate in the cell. The
presence of high levels of oxaloacetate in the tissue can result in
feedback inhibition of succinate dehydrogenase and prevention of succi-
nate oxidation. Effects of this type might result from initial enzyme
inactivation caused by high levels of pentachlorophenol in the tissue.
Total breakdown of mitochondrial integrity was also reported and could
be the final stage of pentachlorophenol toxicity in the cell.
D.6.2.2.2 Local and Systemic Pathology — Both pentachlorophenol
and sodium pentachlorophenate can cause local inflammation of the skin
on contact. In experiments with rabbits, pentachlorophenol caused irrita-
tion of the skin with marked local damage, the intensity of which varied
with different solvents (Deichmann et al., 1942). Solutions in petroleum
solvents were more likely to cause injury than those in vegetable oils.
A 10% solution of sodium pentachlorophenate in water caused edema, in-
flammation, excoriation, and desquamation of the skin of rabbits receiv-
ing^ a single application (Boyd et al., 1940). Cutaneous application of
a 1% aqueous solution of sodium pentachlorophenate to the skin of rabbits
for 100 consecutive days resulted in minor effects (Flickinger, 1971).
The treated areas occasionally showed minor irritation, but this was not
accompanied by wrinkling or cracking of the skin or loss of hair. Solid
sodium pentachlorophenate causes more extensive local damage than solid
pentachlorophenol. Marked irritation or even burns follow prolonged
contact with sodium pentachlorophenate (Dow Chemical Company, 1969a).
-------
377
Prolonged skin contact with pentachlorophenol solid results in only
slight redness (Dow Chemical Company, 1969fc). Skin irritation may develop
after seemingly small exposures to pentachlorophenol in solution. In one
case, immersion of hands for 10 min in a 0.4% solution of pentachlorophenol
caused severe pain and inflammation (Bevenue, Haley, and Klemmer, 1967).
A serious skin disease known as chloracne can result from prolonged
cutaneous contact with technical pentachlorophenol or sodium pentachloro-
phenate. The disease is characterized by the formation of comedones with
or without cysts and pustules (Kimbrough, 1972) and is due to chlorodioxin
contaminants. The follicular orifices are filled with sebaceous and kera-
tinous material. Melanosis and a secondary inflammatory reaction may occur.
Chloracne is one of the most frequent forms of occupational dermatitis, and
many cases have been reported in the United States and Europe, particularly
Germany and England. Behrbohm (1959) gave a detailed account of about 100
cases of skin diseases and irritations (chloracne and dermatitis) resulting
from the use of sodium pentachlorophenate as a wood preservative. Severe
cases of chloracne and eczematous skin lesions among workers engaged in the
production of technical pentachlorophenol have been reported by Baader and
Bauer (1951) and Nomura (1953). Ten percent solutions of sodium penta-
chlorophenate in water and pentachlorophenol in chloroform produced chlor-
acne responses in rabbits (Dow Chemical Company, 1969a, 1969Z?).
The dust, mist, or vapor from heated materials or solutions and
direct contact of solutions with the eyes causes irritation (American
Industrial Hygiene Association, 1970). Pentachlorophenol dust applied
to rabbit eyes caused slight pain and conjunctival redness and, in one
of four animals, slight iritis (Dow Chemical Company, 1969a). Applica-
tion of undiluted Dowicide G (sodium pentachlorophenate) caused marked
pain, moderate to severe conjuctival irritation, severe corneal damage,
and moderate iritis; only minor healing was observed in seven days (Dow
Chemical Company, 1969Z?) .
Concentrations of these compounds in dust and mist greater than
1.0 mg/m3 caused painful irritation in the upper respiratory tract of
persons newly exposed to pentachlorophenol, accompanied by violent sneez-
ing and coughing. Concentrations as high as 2.4 mg/m3 can be tolerated
by those conditioned to exposures (American Industrial Hygiene Association,
1970).
Autopsies of victims of pentachlorophenol poisoning have shown
moderate to gross pathological changes of the gastrointestinal tract,
lungs, spleen, liver, kidneys, and cardiovascular system. The systemic
effects of acute pentachlorophenol poisoning in animals closely mimic
the effects in humans. Pentachlorophenol apparently does not have the
convulsive action of phenol. According to Kehoe, Deichmann-Gruebler,
and Kitzmiller (1939), Boyd et al. (1940), McGavack et al. (1941), and
Deichmann et al. (1942), it produces the following toxicological picture.
A period of general depression is followed by an increase in respiratory
rate and volume. The pulse rate increases and is associated with a pri-
mary rise and subsequent fall of the blood pressure (in the absence of
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378
electrocardiographic changes); neuromuscular weakness develops, especial-
ly towards the end, with a rise of the body temperature. At the time of
the rise of body temperature, the blood sugar level is increased and
sugar is excreted in the urine, which, according to McGavack et al.
(1941), results in depletion of the glycogen content of the liver so that
the final convulsive seizures may be due to acute hypoglycemia. In addi-
tion, increased peristalsis and thirst, diuresis, and later, oliguria
occur. In fatal poisonings the animals die from heart failure. Boyd et
al. (1940) suggested that the variations in blood sugar of intoxicated
animals may result from pathological changes in the liver caused by
pentachlorophenol and a gradual breakdown of the processes by which the
liver mobilizes carbohydrates and fats. The pathological symptoms men-
tioned above have been noted in experiments on rabbits, dogs, rats, and
guinea pigs, and similar pathological changes have been observed in
human autopsies.
Good data regarding the mechanisms of these pathological changes in
various organs are not available. Probably of greatest importance is
the uncoupling of oxidative phosphorylation, thereby causing severe
metabolic disturbances in tissues where pentachlorophenol reaches a
critical threshold. The general hyperpyrexia caused by pentachlorophenol
may be the indirect cause of many of the pathological changes. Human
autopsy results, as well as data from experimental animals, are discussed
below according to the type of pathology seen in specific organs.
D.6.2.2.2.1 Gastrointestinal tract — Inflamed gastric mucosa and
acute gastritis were noted in fatal cases of pentachlorophenol intoxica-
tion by Menon (1958). He suggested that the presence of these patho-
logical changes were due to entry of pentachlorophenol into the body via
the gastrointestinal route. Pathological changes of the gastrointestinal
tract are not a common finding in pentachlorophenol poisoning; therefore,
the changes noted were likely due to entry of pentachlorophenol via the
oral route.
D.6.2.2.2.2 Lungs — Pathological changes of the lungs following
fatal pentachlorophenol intoxication have been commonly reported. Con-
gestion of the lungs was reported in two fatal cases of pentachlorophenol
poisoning by Blair (1961). Edematous lungs and gross pulmonary conges-
tion in fatal cases of pentachlorophenol poisoning were reported by Gordon
(1956), Menon (1958), Mason et al. (1965), and Bergner, Constantinidis,
and Martin (1965) . Menon (1958) suggested that congestion and edema of
the lungs resulted from uptake via the respiratory route. However, con-
gestion of the lungs and alveoli in cases where the respiratory tract
was not an important route of uptake suggests that a more general patho-
logical condition may exist in the lungs following pentachlorophenol
intoxication. This congestion could be due to general damage to the
cardiovascular system, especially the small vessels (Kehoe, Deichmann-
Gruebler, and Kitzmiller, 1939; Boyd et al., 1940).
D.6.2.2.2.3 Spleen — Splenomegaly was reported in three cases of
fatal pentachlorophenol intoxication by Menon (1958) and Robson et al.
-------
379
D.6.2.2.2.4 Liver — Hepatomegaly, congestion, centrilobular degen-
eration of liver cells, and general fatty degeneration of liver tissue
were reported in autopsies of people who died from pentachlorophenol
intoxication (Gordon, 1956; Bergner et al., 1965; Mason et al., 1965;
Robson et al., 1969). As mentioned before, the hyperglycemia and gly-
cosuria often noted in investigations of experimental animals may be due
to a direct pathological effect of pentachlorophenol on the liver. Gross
hepatomegaly and general liver damage have been frequently reported when
pentachlorophenol is administered to experimental animals. Changes in
the activity of microsomal liver enzymes were reported by Knudsen et al.
(1974) and Goldstein et al. (1977) when pentachlorophenol was included
in the diet of rats (Table D.6.19). In serious cases of pentachloro-
phenol poisoning, Nomura (1953) noted a decrease in the albumin to glob-
ulin ratio and urinary excretion of urobilinogen, suggesting the presence
of some liver lesions.
D.6.2.2.2.5 Kidneys — Kidney damage commonly results from penta-
chlorophenol intoxication. Hydropic and fatty degeneration of renal
tubules and general congestion were reported by Bergner, Constantinidis,
and Martin (1965), Mason et al. (1965), and Robson et al. (1969). A com-
mon finding in both fatal and nonfatal human intoxications is the pres-
ence of metabolic acidosis, proteinuria, and elevated urea nitrogen in
the blood (Chapman and Robson, 1965). These changes in blood chemistry
may be due to the effect of pentachlorophenol on kidney tissue.
D.6.2.2.2.6 Heart — Cardiomegaly and fatty degeneration of the myo-
cardium were reported by Robson et al. (1969).
D.6.2.2.2.7 Aplastic anemia — A case of aplastic anemia due to
pentachlorophenol and tetrachlorophenol was reported by Roberts (1963).
The case involved a 21-year-old truck driver who handled lumber soaked
in a product containing pentachlorophenol and tetrachlorophenol. His
clothing and hands frequently became drenched, and some oral contamina-
tion probably occurred because he was a habitual nail biter. Postmortem
examination failed to reveal any other causes for the aplastic anemia;
therefore, it was concluded that the damage to the bone marrow was caused
by exposure to the two chemicals.
D.6.2.2.2.8 Peripheral neuropathy — Although it has frequently been
noted that pentachlorophenol can cause peripheral neuropathy, a critical
examination of the literature reveals that the cases of peripheral
neuropathy reported after exposure to pentachlorophenol are unclear.
Neuropathy is not part of the usual picture of pentachlorophenol poison-
ing. One man, however, developed various peripheral nerve palsies after
gross overexposure of his arms to pentachlorophenol (Fullerton, 1969).
Seven cases of peripheral neuritis were linked to the use of an insecti-
cide mixture containing pentachlorophenol (Campbell, 1952). The exact
formulation of the insecticide was unknown, but it contained o- and
p-dichlorobenzene, DDT, and pentachlorophenol. The presence of several
substances makes it impossible to reach a definite conclusion as to the
causative agent.
-------
TABLE D.6.19.
ACTIVITY OF MICROSOMAL LIVER ENZYMES IN RATS MAINTAINED ON DIETS
CONTAINING PENTACHLOROPHENOL FOR 12 WEEKS
Number ... -
, Week of „
and sex . . Enzyme
.. . experiment J
of rats
6 males
4 males
4 females
, Average ±
6 Aniline hydroxylase
Aminopyrine demethylase
Glucose-6-phosphatase"
12 Aniline hydroxylase
Aminopyrine demethylase
Glucose-6-phosphatase"
12 Aniline hydroxylase
Aminopyrine demethylase
Glucose-6-phosphatase"
standard deviation.
Enzyme activity at various levels of
pentachlorophenol in diet (micromoles/llter)17
0 mg/kg
163
19
92
196
36
148
264
23
93
+
±
i
±
±
±
-\
±
±
45
7
38
42
5
22
45
6
11
25 mg/kg
170
17
90
222
34
144
249
17
100
±
±
±
+
f
±
±
±
±
46
11
30
28
13
10
53
4
7
50 mg/kg
202
30
102
281
44
130
290
18
127
± 44
± 15
i; 36
± 58
± 8
± 19
± 37
± 7
± 26
200
261
33
79
410
52
116
391
21
104
mg/kg
: 54^
llr'
- 18
58f'
-: 17
± 35
+ 46C
J 6
± 14
0.05.
Activity expressed as units per milliliter. A unit is the amount of enzyme needed to
catalyze the transformation of 1 micromole substrate per minute.
eP < 0.001.
u>
oo
o
Source:
publisher.
Adapted from Knudsen et al., 1974, Table IV, p. 146. Reprinted by permission of the
-------
381
Another case of peripheral neuritis was reported by Wagle (1974).
The use of an antitermite formulation resulted in the stiffening of
finger joints with partial incapacitation of both hands. The formula-
tion was found to contain dieldrin (0.5%), pentachlorophenol (1%), tar
acids (1%), and a xylene-kerosene (1:9) solvent base. As in the previous
case, the presence of other substances prevents ascribing this neuritis
to pentachlorophenol. The question of whether or not pentachlorophenol
causes peripheral neuritis remains an open one. It seems, however, that
if pentachlorophenol were a significant causative agent in the develop-
ment of peripheral neuritis, many more cases would have been reported
over the time span in which pentachlorophenol has been used.
D.6.2.2.3 Acute Toxicity — Dose-response curves are difficult, if
not impossible, to determine accurately with human data because varying
exposure conditions permit only estimates of actual doses. Whenever
possible, data from experimental animals are extrapolated to humans.
Absorption of pentachlorophenol in amounts sufficient to cause
systemic intoxication can occur by the oral, respiratory, or cutaneous
routes, and, of course, occupationally exposed persons are subject to
the greatest hazard. Although members of the general population exhibit
a low level of pentachlorophenol contamination (Bevenue et al., 1967;
Cranmer and Freal, 1970), they do not have symptoms found in occupa-
tionally exposed individuals. People poisoned by acute or chronic high-
level doses show similar symptoms: weight loss, general weakness, fatigue,
dizziness, mental weakness, headache, anorexia, nausea and vomiting, dys-
pnea, hyperpyrexia, respiratory distress, tachycardia, hepatomegaly, pro-
fuse perspiration, and an elevated basal metabolic rate (Nomura, 1953;
Truhaut, Boussemart, and L'Epee, 1952; Bergner, Constantinidis, and
Martin, 1965; Robson et al., 1969). These symptoms have been found in
both fatal and nonfatal intoxications. In acute cases, onset of symptoms
may be very rapid, with death ensuing in 3 to 30 hr. The most common
symptoms are general weakness, weight loss (in chronic cases), and pro-
fuse perspiration. The clothes of one individual admitted to a hospital
in a semicomatose condition following exposure to pentachlorophenol were
so wet that the admitting examiners incorrectly surmised that he had been
dragged from a nearby river. The cause of fever and profuse sweating is
the uncoupling of oxidative phosphorylation accompanied by the equivalent
of tissue hypoxia. The hyperpyrexia itself may be the primary factor in
bringing about circulatory and respiratory failure by virtue of the
central and peripheral effects of the fever, as in the case of heat stroke
(Mason et al., 1965).
Only about 51 cases of poisoning from pentachlorophenol ingestion
or absorption have been reported, but 30 of those resulted in death.
No specific treatment for the poison is known, and the deaths took place
in spite of the conventional supportive therapy (Anonymous, 1970).
Successful treatment of pentachlorophenol poisoning was reported by
Robson et al. (1969) in a case of epidemic pentachlorophenol poisoning
among infants in a St. Louis nursery. Sodium pentachlorophenate in
diapers and hospital linens was absorbed cutaneously by the infants.
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382
Nine infants between the ages of 6 and 14 days were severely affected.
The course of the illness was rapid, with progressive deterioration.
One infant died within 3 hr following onset of the first symptom; another
died before she could be given an exchange transfusion. Of the seven who
had severe symptoms, six underwent exchange blood transfusions (the same
treatment used in cases of erythroblastosis) . They improved promptly and
survived. Eleven other children who showed less serious forms of the
illness survived without any active treatment. Most cases of pentachloro-
phenol poisoning are in adults exposed to large quantities of the chemical.
These infants were repeatedly exposed to relatively small quantities in
fabrics. Armstrong et al. (1969) suggested that the increased suscepti-
bility shown by these infants may have resulted from their immature renal
functions. Nomura (1953) also suggested that susceptibility to penta-
chlorophenol poisoning may depend on ability to excrete pentachlorophenol.
Truhaut, Boussemart, and L'Epee (1952) demonstrated that nephritic rabbits
were more sensitive to pentachlorophenol than normal animals.
Relatively high pentachlorophenol levels in the blood and urine of
workers involved with wood preservatives are numerous (Casarett et al.,
1969). Some concentrations reported for blood and urine in cases of
acute pentachlorophenol intoxications are no greater than two to five
times the high values reported for apparently healthy workers involved
in timber dipping operations. Urinary levels of pentachlorophenol
reported in fatal and nonfatal cases (Table D.6.20) show that levels in
fatal and nonfatal poisonings overlap to a considerable extent. Thus,
the margin between fatal and nonfatal pentachlorophenol poisoning and
apparent good health may be extremely narrow. The exact dosage of penta-
chlorophenol required to produce illness in humans is not known. Symptoms
occur at concentrations of 40 to 80 mg/liter in the blood. Pentachloro-
phenol is excreted in the urine at levels of 3 to 60 mg/liter in nonfatal
cases. Blood levels noted in fatal cases ranged from 46 to 156 mg/liter
and urine levels from 28 to 520 mg/liter. The Registry of Toxic Effects
of Chemical Substances (Christensen and Luginbyhl, 1975) gives the oral
lethal dose of pentachlorophenol as 29 mg/kg body weight. Based on this
figure, a 150-lb man would have to absorb nearly 2 g of pentachlorophenol
of sodium pentachlorophenate before it would be lethal. As noted previ-
ously, for persons whose ability to excrete the compound is hindered in
some way, the lethal dose may be considerably lower (Armstrong et al..
1969).
The lethal doses of sodium pentachlorophenate and pentachlorophenol
administered via the oral and cutaneous routes to experimental animals
are given in Table D.6.21. The lethal oral dose of pentachlorophenol
ranges from 27 to 205 mg/kg body weight in rats, rabbits, and guinea pigs.
The 27 mg/kg dose was administered to the rat in fuel oil. The contribu-
tion of the fuel oil to the lethality is unknown. The cutaneous lethal
doses ranged from 100 to 200 mg/kg body weight in rabbits. Similar values
were found for sodium pentachlorophenate tested in experimental animals.
The oral acute dose in rats, rabbits, and guinea pigs is 80 to 274 mg/kg
body weight, and the cutaneous acute dose is 100 to 300 mg/kg body weight.
The toxicity of pentachlorophenol depends on the solvent in which it is
applied. The varying values mentioned above are for various solvents
-------
TABLE D.6.20. PENTACHLOROPHENOL LEVELS IN URINE OF FATALLY AND NONFATALLY POISONED HUMANS
Compound
Individual
and occupation
Pentachlorophenol
in urine
(mg/liter)
Source
Sodium pentachlorophenate
Pentachlorophenol
Fatally poisoned
22-year-old male,
dipping planks in
preservative
16-year-old male,
spraying pineapples
14-year-old male,
spraying watercourses
for snail control
Male, bagging penta-
chlorophenol at
chemical factory
Nonfatally poisoned
3-year-old female,
accidental
36-year-old male,
dipping planks
21-year-old male,
dipping planks
38-year-old male,
dipping planks
30-year-old male,
dipping planks
160
70
28
520
60
18
3.8
5.4
10
Menon, 1958
Gordon, 1956
Blair, 1961
Mason et al., 1965
Chapman and Robson, 1965
Bergner, Constantinidis,
and Martin, 1965
Bergner, Constantinidis,
and Martin, 1965
Bergner, Constantinidis,
and Martin, 1965
Bergner, Constantinidis,
and Martin, 1965
00
OJ
-------
TABLE D.6.21.
LETHAL DOSES OF PENT'ACHLOROPHENOL AND SODIUM PENTACHLOKOPIIKNATE ADM1NLSTKKED
ORALLY AND CUTANEOUSLY TO RATS, RABBITS, AND GUINEA PICS
Route of
administration
Solvent
Animal
Dose
(mg/kg body wt)
Source
Pentachlorophenol
Oral
Cutaneous
11% in olive oil
5% in fuel oil
Not known
1% in olive oil
0.5% in fuel oil
Various, not known
Not known
Rabbit
Rabbit
Rat, male
Rat, female
Rat
Rat
Rabbit
Rabbit
100-130a
70-90a
205
135
78b
27b
40-170a
100-200
McCavack et al. , 1941
Deichmann et al., 1942
Dow Chemical Company, 1969a
Dow Chemical Company, 1969a
Deichmann et al., 1942
Deichmann et al., 1942
Deichmann et al., 1942
Dow Chemical Company, 1969a
Sodium pentachlorophenate
Oral
Cutaneous
Aqueous
Aqueous
Aqueous
Aqueous
Aqueous
Aqueous
Aqueous
Aqueous
Aqueous
Aqueous
Rabbit
Rabbit
Rabbit
Rat
Rat
Guinea pig
Rabbit
Rabbit
Rabbit
Guinea pig
218a
275
250-300a
210
211
80-160
25 Oa
450-600a
100-300
266a
Kehoe , Deichmann-Gruebler ,
and Kitzmiller, 1939
Dow Chemical Company, 1969£>
Deichmann et al., 1942
Dow Chemical Company, 1969&
Deichmann et al., 1942
Dow Chemical Company, 19692?
Deichmann et al. , 1942
McGavack et al., 1941
Dow Chemical Company, 1969&
Kehoe, Deichmann-Gruebler,
and Kitzmiller, 1939
00
-p-
TMinimum lethal dose.
LD90 value.
-------
385
under various conditions. The dose-response relationship of sodium penta-
chlorophenate cutaneously applied to rabbits is given in Table D.6.22.
Pentachlorophenol appears to be more toxic to mammals than sodium penta-
chlorophenate, at least when the route of administration is oral or cutane-
ous (Table D.6.23). With subcutaneous administration the difference in
toxicity disappears. Differential absorption may explain this phenomenon.
The toxicity of pentachlorophenol or sodium pentachlorophenate may be
influenced by three factors: (1) ambient temperature, (2) renal competency,
and (3) general health. Most cases of fatal pentachlorophenol poisoning
have occurred when ambient temperatures were high — approximately 27 °C to
33°C. The increased volatility of pentachlorophenol at higher temperatures
may increase the amount absorbed by inhalation. Because a primary effect
of pentachlorophenol intoxication is hyperpyrexia, the increased toxicity
of pentachlorophenol whem ambient temperatures are high may be due to
increased difficulty in dissipating the excess heat generated by the un-
coupling of oxidative phosphorylation.
The renal competency of pentachlorophenol-intoxicated persons deter-
mines their tolerance to exposure. Deichmann et al. (1942) found that
tolerance developed in rabbits when sublethal oral doses of pentachloro-
phenol were repeatedly administered. Such a tolerance effect has not
been demonstrated in humans. However, a tolerance to the respiratory
distress caused by high atmospheric levels of pentachlorophenol occurs
in occupationally exposed workers as distinct from a general systemic
tolerance to the compound.
A third factor which may influence the toxicity of pentachlorophenol
to man is general health (Menon, 1958). All nine deaths from pentachloro-
phenol poisoning in Sarawak, Borneo, were members of true native races
(e.g., Dyak and Kayan) rather than the Chinese or Malays, even though as
many, if not more, of these normative races were working on the same job.
The native races had average heights of 5 ft 4 in. and weights of 45 to
50 kg, and most were suffering from mixed worm infestation and malaria.
In almost every case their diet was rice with little or no protein. The
general poor health and physique of these people probably enhanced the
toxic responses seen following exposure to pentachlorophenol.
D.6.2.2.4 Chronic Toxicity
D.6.2.2.4.1 In experimental am'mgls — The effects of chronic levels
of pentachlorophenol administered to experimental animals are difficult
to determine. Attempts to produce high-dose chronic intoxications via
the cutaneous route have been difficult because of the severe local
reactions. Low-dose, chronic systemic intoxications, in general, have
not been shown via the cutaneous route. Cutaneous application of penta-
chlorophenol at levels low enough to avoid gross skin damage resulted in
no chronic systemic disease in rabbits (Kehoe, Deichmann-Gruebler, and
Kitzmiller, 1939).
Table D.6.24 shows the results of daily administering subcutaneous
or intraperitoneal doses of sodium pentachlorophenate to rabbits.
-------
386
TABLE D.6.22. CLINICAL EFFECTS OF CUTANEOUS ADMINISTRATION OF
SODIUM PENTACHLOROPHENATE TO RABBITS
Dose
(mg/kg)
50
100
150
200
250
300
350
400
450
500
550
600
Average
temperature
4 hr after
dosea
(°C)
39.8
40.2
40.1
39.6
40.3
40.6
40.6
39.4
40.6
42.4
Average
blood sugar
4 hr after dose
(mg/100 ml)
141
256
238
243
Number of
defecations
during 4 hr
2
3
8
7
7
9
7
4
9
8
17
Died
(%)
0
0
0
0
0
33
0
0
50
100
50
100
^Ttormal body temperature is approximately 39.4°C.
Source: Adapted from Boyd et al., 1940, Table I, p.
Reprinted by permission of the publisher.
324.
TABLE D.6.23. COMPARISON OF THE TOXICITIES OF
PENTACHLOROPHENOL AND SODIUM PENTACHLOROPHENATE TO RABBITS
Route of
administration
Compound and solvent
Lethal dose
(mg/kg)
Cutaneous
Oral
Subcutaneous
5% pentachlorophenol in
Stanolex fuel oil 60-70
10% sodium pentachlorophenate
in water 250
5% pentachlorophenol in
Stanolex fuel oil 70-90
10% sodium pentachlorophenate
in water 250-300
5% pentachlorophenol in olive
oil 70-85
10% sodium pentachlorophenate
in water 100
Source: Adapted from Deichmann et al., 1942, Table 1,
p. 106. Reprinted by permission of the publisher.
-------
TABLE D.6.24. CHRONIC TOXICITY OF SODIUM PENTACHLOROPHENATE TO RABBITS
Number
of
rabbits
6
6
6
3
Route of
administration
Subcutaneous
Subcutaneous
Subcutaneous
Intraperitoneal
Daily
dose
(mg/kg)*
13.7
27.5
70.0
15.0
Average
number of
injections
52
15
8
11
Average
total
dose
(mg)
716
401
516
165
Number of rabbits
Died
0
6
6
3
Decreased
weight
3
4
6
3
Stationary
weight
0
2
0
0
Increased
weight
3
0
0
0
Minimum lethal doses were 150 mg/kg body weight by intraperitoneal injecLion and 275 mg/kg body
weight by subcutaneous application in a single dose.
Source: Adapted from McGavack et al., 1941, Table 3, p. 244. Reprinted by permission of the
publisher.
LO
oo
-------
388
McGavack et al. (1941) found that the amount of sodium pentachlorophenate
necessary to cause death in small, divided doses was very close to the
minimum lethal dose recorded when a single administration of the com-
pound was studied.
When daily doses of sodium pentachlorophenate were administered to
rabbits at a dose rate of 1 mg/kg body weight for 90 days, no systemic
effects were found and blood levels of pentachlorophenol were undetect-
able (Machle, Deichmann, and Thomas, 1943). However, when pentachloro-
phenol was fed to rabbits at a dose rate of 3 mg/kg body weight over a
90-day period, blood levels of 0.6 mg per 100 ml of blood were reported.
No systemic effects were found at these dose levels (Deichmann et al.,
1942). These levels of pentachlorophenol in blood (0.6 mg per 100 ml)
were approximated closely by skin application of sodium pentachloro-
phenate at a rate of 100 mg/day for 100 daily doses. This dose schedule
resulted in a level of 0.45 mg per 100 ml. For comparative purposes,
levels of pentachlorophenol in blood of rats following a lethal dose of
pentachlorophenol reportedly ranged from 4.5 to 8.0 mg per 100 ml
(Deichmann et al., 1942).
Studies of the effects of chronic ingestion of pentachlorophenol or
sodium pentachlorophenate have been complicated by the fact that these
substances are repellent to animals. Thus, food intake generally de-
creases, and loss of weight is seen as a result of the decreased food
intake. In such cases, pathological changes in the dosed animals were
not seen. If the amount of pentachlorophenol or sodium pentachlorophenate
in the diet is reduced to a very small sublethal dose, no chronic systemic
disease is apparent. Daily doses of sodium pentachlorophenate adminis-
tered orally to rabbits at a level of 1 mg/kg body weight for 90 days
resulted in no poisoning and only very limited retention of the compound
in the blood (Machle, Deichmann, and Thomas, 1943). Daily feeding of
sodium pentachlorophenate at a level of 3 mg/kg body weight to rabbits
resulted in no signs of acute poisoning but showed a blood accumulation
of up to 0.6 mg pentachlorophenol per 100 ml.
Inclusion of pentachlorophenol or sodium pentachlorophenate in the
diet of cats resulted in a decreased intake of food (Deichmann et al.,
1942). Cats totally refused food containing pentachlorophenol at a
level which, with normal intake of food, would result in a dose of 5 to
10 mg/kg body weight. When the pentachlorophenol content was decreased,
it was possible to expose the cats to 1.25 to 2.5 mg/kg body weight
daily. This diet was fed for ten weeks. Some loss of weight and appetite
occurred, and pentachlorophenol levels of 0.3 to 1.8 mg per 100 g of blood
were found. Application of pentachlorophenol in mineral oil to the skin
of rabbits at a dose rate of 40 mg/kg for 21 consecutive days did not
result in illness, weight loss, or skin injury. Application of sodium
pentachlorophenate to the skin at a dose level of 40 mg/kg for 100 con-
secutive days also resulted in a normal weight gain and no fatalities
(Deichmann et al. , 1942). When 113 mg/kg sodium pentachlorophenate was
administered cutaneously, death resulted following two consecutive daily
treatments.
-------
389
Rabbits showed some degree of tolerance when substantial doses of
pentachlorophenol were administered over a period of time. Deichmann
et al. (1942) administered pentachlorophenol to rabbits at a daily dose
rate of 35 mg/kg (12% of the minimum lethal dose) for 15 days. For the
following 19 days, daily doses were gradually increased to 600 mg/kg
(twice the minimum lethal dose). A loss of weight and a decrease in
erythrocyte and hemoglobin counts were noted. Analysis of the blood
following death revealed levels of pentachlorophenol ranging fro- 14 to
39 mg per 100 g. These levels are approximately ten times the levels
seen in animals poisoned by a single lethal dose of pentachlorophenol.
Several 90-day or longer studies of chronic pentachlorophenol toxic-
ity have been reported in recent years. Kimbrough and Linder (1975) fed
a relatively pure pentachlorophenol (containing low levels of chloro-
dibenzo-p-dioxin contaminants) to a group of ten male rats and fed com-
mercial pentachlorophenol (containing a relatively high concentration of
these contaminants) to a second group for 90 days. A level of 1000 mg
pentachlorophenol per kilogram food, equivalent to approximately 50 mg/kg
body weight per day, was fed to the rats, and liver changes were examined
by light and electron microscopy. Enlargement of hepatocytes was observed
in livers of rats fed purified pentachlorophenol; technical grade penta-
chlorophenol caused foamy cytoplasm, vacuoles, inclusions, single hepa-
tocellular necrosis, slight interstitial fibrosis, and prominent brown
pigment in macrophages and Kupffer's cells. Electron microscopic analy-
sis showed an increase in the smooth endoplasmic reticulum of the group
fed technical pentachlorophenol and less change in the rats fed purified
pentachlorophenol. There were many lipid vacuoles in the former group
and some in the latter. Atypical mitochondria were observed in the
livers of both groups.
Knudsen et al. (1974) fed weanling Wistar rats diets containing
25, 50, and 200 mg pentachlorophenol per kilogram food (approximately
1.5, 3, and 14 mg/kg body weight respectively) for 12 weeks. Examina-
tion of the results in Table D.6.25 shows that a number of the observed
changes do not fit a dose-response pattern. For example, female rats
fed 25 and 200 mg/kg gained less weight than the controls, but the inter-
mediate group receiving 50 mg/kg did not show this effect. Blood urea
increased in the females receiving 25 mg/kg but not in rats fed the two
higher doses. Some of these changes could be differences cue to chance;
the statistical method used was Student's t test. More appropriate
statistical methods are available for making multiple comparisons of
graded treatment levels with a common control group. Hemoglobin values
and the number of erythrocytes decreased in groups of male rats fed 50
and 200 mg/kg. In addition to the results shown in Table D.6.25, relative
liver weight increased in the females fed 50 and 200 mg/kg. There was
an apparent increase in centriobular vacuolization in the livers in these
groups; however, vacuolization was also seen in control males. The liver
enzyme data are given in more detail in Table D.6.19.
An interesting effect of pentachlorophenol on the kidneys of rats
given dietary levels of pentachlorophenol for 12 weeks was reported by
Knudsen et al. (1974). The histopathology of liver and kidney tissues
-------
TABLE D.6.25. TOXICITY OF PENTACHLOROPHENOL TO RATS IN A 12-WEEK FEEDING STUDYa
Effect of pentachlorophenol
Parameter
Feed consumption
Body weight
Biochemistry (12 weeks)
Serum glutamic-pyruvic
trans aminase
Alkaline phosphatase
Urea
Glucose
Liver enzymes (12 weeks)
Aniline hydroxylase
Aminopyrine demethylase
Glucose-6-phosphate
Hematology (11 weeks)
Hemoglobin
Hematocrit
Erythrocyte count
25 mg/kg
0
0
0
0
0
0
0
0
0
0
0
0
Malesc
50 mg/kg
0
0
0
0
0
0
0
0
<
<
0
<
200 mg/kg
0
0
0
0
0
>
>
0
0
<
0
<
at various
25 mg/kg
0
<
0
0
>
0
0
0
0
0
0
0
levels in feed^5
Females'3
50 mg/kg 200
0
0
0
0
0
0
0
0
0
0
0
0
mg/kg
0
<
0
0
>
0
>
0
0
0
0
0
Technical grade pentachlorophenol with 200 mg/kg octachlorodibenzo-p-dioxin and unspecified
hexachlorodibenzo-p-dioxin content.
^Statistical analysis by Student's £ test. 0 indicates no effect; > indicates an increase;
< indicates a decrease.
cTen males and ten females per group.
Source: Compiled from Knudsen et al., 1974.
U)
VO
o
-------
391
is shown in Table D.6.26. A dose-related decrease of calcium deposits
in the kidney was indicated. Knudsen et al. (1974) suggested that this
effect on calcium deposition in the kidney may arise when:
(a) PCP or a metabolite has chelating properties. This does
not seem very likely in view of the chemical structure of the
parent compound.
(b) Calcium deposits are not formed due to the acidity of the
pre-urine. However, the pH of the urine in all groups was 6
when checked in week 11, so no differences were observed be-
tween control and test groups. This is evidence against such
a possibility, although pH is not measured at other time
intervals.
(c) The Ca2 -blood level is lowered through an indirect action
of PCP on the calcium metabolism. A number of mechanisms might
account for this observation. Normally calcium metabolism de-
pends on the adrenals, parathyroid and pituitary glands. More
work is needed to elucidate the reason for the decreased calcium
deposits.
Goldstein et al. (1977) fed weanling female rats (Sherman strain)
either pure (reagent grade) or technical grade pentachlorophenol for
eight months in a study designed to evaluate liver enzyme induction.
The rats received 20, 100, and 500 mg pentachlorophenol per kilogram of
feed, which is approximately equal to 1.2, 6, and 30 mg/kg body weight
respectively. The results are summarized in Table D.6.27. Pure penta-
chlorophenol was not an inducer of aryl hydrocarbon hydroxylase, amino-
pyrine-#-demethylase, cytochrome P-450, or ALA synthetase. A high dose
of pure pentachlorophenol did increase the activity of glucuronyl trans-
ferase. Technical pentachlorophenol with dioxin and furan contaminants
induced aryl hydrocarbon hydroxylase and glucuronyl transferase at all
dosage levels. Cytochrome P-450 activity increased at the two higher
dosages. The increase in liver enzymes was accompanied by an increase
in absolute and relative liver weight. In addition, about one-third of
the rats fed diets containing 100 or 500 mg technical pentachlorophenol
per kilogram of food had an increase in total liver porphyrins, mainly
uroporphyrins. Neither pure nor technical pentachlorophenol induced
aminopyrine-7V-demethylase activity, which is consistent with the results
of Knudsen et al. (1974). It is apparent that the contaminants in tech-
nical pentachlorophenol are inducers of several liver enzymes involved
in metabolism of chemicals. Additionally, both pure and technical penta-
chlorophenol decreased the amount of body weight gained during the eight
months of feeding. The rats weighed 100 g each at the beginning of the
experiment; final weights were 310 g for controls, 270 g for rats fed
500 mg pure pentachlorophenol per kilogram of food, and 245 g for rats
fed 500 mg technical pentachlorophenol per kilogram food.
Kociba et al. (1971) fed male, seven-week-old, Sprague-Dawley rats
pure or technical pentachlorophenol for 90 days at dosages of 0, 3, 10,
and 30 mg/kg body weight (Table D.6.28). There were small depressions
-------
TABLE D.6.26.
HISTOPATHOLOGY OF LIVER AND KIDNEY TISSUES FOLLOWING ORAL ADMINISTRATION
OF PENTACHLOROPHENOL TO RATS FOR 12 WEEKS
Number of rats affected at various levels of
pentachlorophenol in fooda
Alteration to organs
Liver
Bile duct proliferation
Centrilobular vacuolization
Kidney
Basophilic proximal tubules
Some calculi, in cortico-
medullary junction
Moderate number of calculi
Many calculi
Hydronephrosis
0
Males
1
0
0
0
2
6
1
mg/kg
Females
0
2
0
0
0
0
0
25
Males
0
0
1
2
4
4
0
mg/kg
Females
0
0
0
0
0
0
0
50
Males
1
0
0
2
4
2
0
mg/kg
Females
1
4
0
0
0
0
0
200
Males
1
2
0
3
1
1
0
mg/kg
Females
0
5
0
0
0
0
0
a
Ten males and ten females per group.
Source: Adapted from Knudsen et al., 1974, Table VII, p. 149. Reprinted by permission of the
publisher.
-------
393
TABLE D.6.27. HEPATIC EFFECTS OF PURE AND TECHNICAL GRADE PENTACHLOROPHENOL
IN FEMALE RATS DURING AN EIGHT-MONTH FEEDING STUDYa
Effect of pentachlorophenol
at various levels in
Parameter
Pure'
Technical grade6
20
mg/kg
100
mg/kg
500
mg/kg
20
mg/kg
100
mg/kg
500
mg/kg
Liver enzymes
Aryl hydrocarbon hydroxylase
Aminopyrine tf-demethylase
Cytochrome P-450
Glucuronyl transferase
ALA synthetase
Microsomal heme
Liver/body weight
Absolute liver weight
Coproporphyrin
Uroporphyrin
Urinary ALA
PEG
Body weight
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
>
0
0
0
0
0
0
0
0
<
>
0
0
>
0
0
0
0
0
0
0
0
0
>
0
>
>
0
>
>
0
>
0
>
0
0
>
0
>
>
0
>
>
>
>
0
>
0
<
Statistical analysis by analysis of variance followed by Duncan's
multiple-range test at P = 0.05. Six rats per group.
^0 indicates no significant effect; > indicates a significant increase;
< indicates a significant decrease.
^From Aldrich Chemical Company; >99% pure.
"Contained 8 mg/kg hexachlorodibenzo-p-dioxin, 520 mg/kg heptachlorodi-
benzo-p-dioxin, 1380 mg/kg octachlorodibenzo-p-dioxin, 4 mg/kg tetrachloro-
dibenzofuran, 40 mg/kg pentachlorodibenzofuran, 90 mg/kg hexachlorodibenzofuran,
400 mg/kg heptachlorodibenzofuran, and 260 mg/kg octachlorodibenzofuran. From
Monsanto Chemical Company.
Source: Compiled from Goldstein et al., 1977-
in the erythrocyte counts (7.75 x 10s vs 8.18 x 106), hemoglobin (15.3 g
vs 16.7 g), and packed cell volume (46.4% vs 51.3%) in rats fed 30 mg
technical pentachlorophenol .per kilogram. There was no effect on the
renal parameters measured. In rats fed technical pentachlorophenol the
alkaline phosphatase increased (26.0 King-Armstrong units at 3 mg/kg and
25.7 King-Armstrong units at 30 mg/kg vs 20.5 King-Armstrong units for
controls). Serum glutamic-pyruvic transaminase increased in the rats
receiving high doses of technical pentachlorophenol (74.8 vs 61.0 Karmen
units). Serum albumin decreased in the 30 mg/kg group (2.3 g per 100 ml)
-------
394
TABLE D.6.28. COMPARISON OF THE TOXICITIES OF PURE AND TECHNICAL GRADE
PENTACHLOROPHENOL IN MALE RATS IN A 90-DAY STUDYa
Effect of pentachlorophenol
at various levels^1
Parameter
Pure
Technical grade
3 10 30 3 10 30
mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg
Body weight
Food consumption
Hematology (five per group, day 83)
Hemoglobin
Erythrocyte count
Packed cell volume
Total and differential
leucocyte count
Urinalysis
PH
Sugar
Albumin
Ke tones
Occult blood
Clinical chemistry
Blood urea nitrogen
Alkaline phosphatase
Serum glutamic-pyruvic
transaminase
Albumin
Protein
Organ weight (absolute)
Liver
Kidney
Organ weight (relative)
Liver
Kidney
0
0
0
0
0
0
ND
ND
ND
ND
ND
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ND
ND
ND
ND
ND
0
0
0
0
0
0
0
>
0
0
0
0
0
0
0
0
0
0
0
0
>
<
0
0
0
>
0
>
>
0
0
0
0
0
0
ND
ND
ND
ND
ND
0
>
0
0
0
0
0
>
>
0
0
0
0
0
0
ND
ND
ND
ND
ND
0
0
0
<
0
>
0
>
>
0
0
<
<
<
0
0
0
0
0
0
0
>
>
<
0
>
>
•>
>
Ten rats per group. Dietary levels were adjusted weekly to compensate for
changes in body weights and rates of food consumption. Statistical analysis by
Student's t test.
0 indicates no statistically significant change; > indicates a statistically
significant increase; < indicates a statistically significant decrease; ND means
not determined.
Combination of 95% purified pentachlorophenol and 5% purified tetrachloro-
phenol containing <0.5 mg/kg dibenzodioxins or dibenzofurans.
Production grade material containing 2500 mg/kg octachlorodibenzo-p-dioxin,
125 mg/kg heptachlorodibenzo-p-dioxin, 4 mg/kg hexachlorodibenzo-p-dioxin, 80
mg/kg octachlorodibenzofuran, 80 mg/kg heptachlorodibenzofuran, and 30 mg/kg
hexachlorodibenzofuran.
Source: Compiled from Kociba et al., 1971. Results have also been reported
in part by Schwetz, Gehring, and Kociba, 1973, and Johnson et al., 1973.
-------
395
and the 10 mg/kg group (2.5 g per 100 ml) compared with the controls
(2.7 g per 100 ml). There were no changes in total serum proteins. In
rats fed the high dose of pure pentachlorophenol there was an increase
in blood urea nitrogen (18 vs 15 mg per 100 ml) and a decrease in alka-
line phosphatase (17.0 vs 21.4 King-Armstrong units). Relative liver
and kidney weights increased at all dosage levels in the groups fed
technical pentachlorophenol. In the groups receiving pure pentachloro-
phenol, relative liver weights increased in the two higher-dose groups
and relative kidney weight increased in the high-dose group only. Patho-
logic changes were found only in the livers of rats fed the high dose of
technical pentachlorophenol. Seven of ten rats showed minimal focal
hepatocellular degenerative changes, and three of ten showed minimal
focal hepatocellular necrosis. Both controls and treated groups had
intestinal nematodiasis. It should be noted that these investigators
used Student's t test in the statistical analysis of the data. As men-
tioned previously, more appropriate methods are available for making
multiple comparisons of graded treatment levels with a common control
group.
Kociba et al. (1973) fed male and female, seven-week-old, Sprague-
Dawley rats pentachlorophenol with a low nonphenolic content for 90 days;
the results are presented in Table D.6.29. The hematologic parameters
were determined in the control and high-dose groups, and there were no
differences. Similarly, the urinalysis and clinical chemistry variables
were not altered. There were differences in liver and kidney weights in
rats receiving higher doses. There were no treatment-related histo-
pathologic changes. The no-effect level was reported as 3 mg/kg body
weight.
Schwetz et al. (1976, 1978) fed weanling, male and female, Sprague-
Dawley rats 0, 1, 3, 10, or 30 mg/kg pentachlorophenol with a low non-
phenolic content for 24 months (females) or 22 months (males). The
results are given in Table D.6.30. The changes observed in terminal
samples were a decrease in body weight in high-dose females and an
increase in serum glutamic-pyruvic transaminase activity in high-dose
males and females. At one year, but not at the termination of the study,
there was a small increase in urine specific gravity in high-dose females.
The males were terminated two months earlier than the females because of
death losses in male controls and the four male treatment groups. The
study included microscopic examination of tissues. The incidence of
changes was statistically analyzed by the Fisher exact probability test.
An accumulation of pigment was observed in the liver and kidney of females
fed 10 and 30 mg/kg. The brown, granular pigment in the liver was pri-
marily found in the hepatocytes surrounding the central veins. In the
kidney the pigment was in the proximal convoluted tubular epithelium.
The pigment was not identified. It did not stain with any of the fol-
lowing techniques: oil red-0, nile blue sulfate, acid-fast, Gomori's
stain for iron, McManus' periodic acid—Schiff, Hall's method for bili-
rubin, and Stein's method for bile pigments. The pigment was not ob-
served grossly in the males but was found microscopically in the liver
of one high-dose male. No other nontumorous pathologic changes related
to ingestion of pentachlorophenol were observed.
-------
396
TABLE D.6.29. TOXICITY OF PENTACHLOROPHENOL WITH A LOW NONPHENOLIC CONTENT TO
RATS DURING A 90-DAY STUDY1
•a
Effect of pentachlorophenol at various levels
Parameter
Females'"
Males
1 3 10 30 1 3 10 30
mg/kg mg/kg mg/kg tng/kg mg/kg mg/kg mg/kg mg/kg
Body weight (final) 000<>000
Food consumption 00000000
Hematology (five per group, day 83)
Packed cell volume ND ND ND 0 ND ND ND 0
Erythrocyte count NDNDNDO NDNDNDO
Hemoglobin ND ND ND 0 ND ND ND 0
Total and differential
leucocyte count ND ND ND 0 ND ND ND 0
Urinalysis (five per group, day 83)
Specific gravity NDNDNDO NDNDNDO
pH ND ND ND 0 ND ND ND 0
Sugar NDNDNDO NDNDNDO
Protein ND ND ND 0 ND ND ND 0
Ketones NDNDNDO NDNDNDO
Occult blood ND ND ND 0 ND ND ND 0
Bilirubin ND ND ND 0 ND ND ND 0
Clinical chemistry (five per group)
Blood urea nitrogen 00000000
Alkaline phosphatase 00000000
Serum glutamic—pyruvic
transaminase 00000000
Organ weight (absolute)
Liver
Kidney
Organ weight (relative)
Liver
Kidney
0
0
0
0
0
0
0
0
0
0
0
0
0 0
0 0
> 0
> 0
0
0
0
0
> >
0 >
> >
0 >
Compound administered was a distilled form of Dowicide 7, considered to be representative
of the improved product registered as Dowicide EC-7. Nonphenolic content was 1 mg/kg hexachloro-
dibenzo-p-dioxin, 6.5 mg/kg heptachlorodibenzo-p-dioxin, 15.0 mg/kg octachlorodibenzo-p-dioxin,
3.4 mg/kg hexadibenzofuran, and 1.8 mg/kg heptadibenzofuran.
Z>Data analyzed by analysis of variance and Dunnett's test. 0 indicates no statistically
significant change; > indicates a significant increase; < indicates a significant decrease; ND
means not determined.
eTen males and ten females per group.
Source: Compiled from Kociba et al., 1973.
From the above studies it is apparent that the nonphenolic con-
taminants present in technical pentachlorophenol contribute to the bio-
logical activity of pentachlorophenol. The primary evidence of biological
activity is enzyme induction. Dosage levels of 30 to 50 mg/kg body
weight for 90 days to eight months are required to produce pathologic
changes in the liver. This feeding pattern represents prolonged dosing
at one-third to one-fifth the single-dose acute LDS0. The no-effect
level in experimental animals appears to be 3 mg/kg. The level selected
depends on the significance attached to changes in organ weights and to
enzyme induction responses.
-------
397
TABLE D.6.30. CHRONIC TOXICITY OF PENTACHLOROPHENOL WITH LOW NONPHENOLIC
CONTENT TO MALE AND FEMALE RATSa
Effect of pentachlorophenol at various levels
Parameter
Body weight
Food consumption
Hematology
Erythrocyte count
Hemoglobin
Total and differential
leucocyte count
Clinical chemistry
Blood urea nitrogen
Alkaline phosphatase
Serum glutamic-pyruvic
transaminase
Urinalysis
PH
Specific gravity
Sugar
Albumin
Ke tones
Bilirubin
Occult blood
Organ weight (absolute)
Liver
Kidney
Organ weight (relative)
Liver
Kidney
Q
Females
1
mg/kg
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
mg/kg
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
10
mg/kg
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
30
mg/kg
<
0
0
0
0
0
0
>
0
0
0
0
0
0
0
0
0
0
0
1
mg/kg
0
0
ND
ND
ND
0
0
0
ND
ND
ND
ND
ND
ND
ND
0
0
0
0
Males
3
mg/kg
0
0
ND
ND
ND
0
0
0
ND
ND
ND
ND
ND
ND
ND
0
0
0
0
10
mg/kg
0
0
ND
ND
ND
0
0
0
ND
ND
ND
ND
ND
ND
ND
0
0
0
0
30
mg/kg
0
0
0
0
0
0
0
>
0
0
0
0
0
0
0
0
0
0
0
Composition of pentachlorophenol same as that given in Table D.6.29. In addition,
the pentachlorophenol contained 400 mg/kg hexachlorobenzene. Dietary levels were
adjusted monthly.
^Data analyzed by Dunnett's test. 0 indicates no significant change from the
control; > indicates a significant increase; < indicates a significant decrease; ND
means not determined.
C25 males and 25 females per group.
Source: Compiled from Schwetz et al., 1976, 1978.
-------
398
D.6.2.2.4.2 In humans — Bevenue et al. (1967) surveyed the penta-
chlorophenol content of urine from a cross-section of Hawaiians (Table
D.6.31). As one might expect, substantial pentachlorophenol was found
in the urine of individuals occupationally exposed to the compound;
amounts ranged from 3 to 35,700 yg/liter. A somewhat surprising result,
however, was the detection of substantial pentachlorophenol levels in
the urine of the general population. Levels of pentachlorophenol from
0 to 1840 yg/liter were found in the urine of persons not occupationally
exposed.
The presence of pentachlorophenol in the urine of the general popu-
lation was confirmed by Cranmer and Freal (1970), who reported levels of
pentachlorophenol ranging from 2 to 11 yg/liter (Table D.6.32). The
source of this exposure is unclear. Casarett et al. (1969) suggested
that respiratory tract absorption is a reasonable explanation for the
nearly ubiquitous occurrence of pentachlorophenol in human urine. The
presence of pentachlorophenol in the environment, in food supplies, and
in containers treated with preservatives may contribute to this low-level
contamination in humans. Contamination is particularly likely in areas
where pentachlorophenol is used widely as a wood preservative and/or
herbicide. In Hawaii, pentachlorophenol is used on nearly all wood
products to prevent termite infestation and has been sprayed on pine-
apple fields as a herbicide.
The question of possible long-term chronic effects resulting from
low-dose pentachlorophenol exposure remains open. Evidence exists that
low-dose pentachlorophenol exposure does not result in chronic effects.
Arsenault (1976), in a review of epidemiologic studies since 1967 at the
University of Hawaii Pacific Biomedical Research Center at Manoa, stated
that long-term chronic effects of low-dose pentachlorophenol exposure
appear to be absent:
In a prospective study of an occupationally exposed
population annual physical examinations, blood chemistry
and urinalysis testing were undertaken on all control and
occupationally exposed adults. There were 21 workers having
a mean of 3196 total days of exposure to PCP in an occupation
of treating wood (pressure treatment). Although PCP was used
by 70 other workers, such as pest control operators, the wood
treaters had significantly higher levels of PCP than all other
participants in the study. The mean blood serum level in the
21 workers was 1.05 ppm whereas the control was about 0.1 ppm.
While vertigo and insomnia occurred more frequently among
workers with high serum PCP levels, in tests of workers for
neurological and psychological effects, there were no effects
noted for PCP residue levels. In fact, PCP was the only pesti-
cide of the four studied (PCP, Dieldrin, DDE, and DDT) that
.showed an insignificant contribution in a regression study.
However, Klemmer (1972) noted that the liver enzymes serum glutamic-
oxaloacetic transaminase, serum glutamic-pyruvic transaminase, and lactic
dehydrogenase were at their highest mean levels in persons occupationally
-------
399
TABLE D.6.31. CONCENTRATIONS OF PENTACHLOROPHENOL IN URINE OF HAWAIIAN'S
Group
Occupationally exposed pest
control operators
Total
Nonoccupationally exposed persons
Households
Mosquito control
Office workers
Orchid growers
Rodent control
Hawaii Housing Authority
Hawaii Department of Agriculture
City and county of Honolulu
Division of Forestry
Total
Firm
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Number
of
people
19
15
12
12
11
5
5
5
4
4
3
3
3
3
3
3
2
2
2
2
2
2
1
1
1
1
1
1
1
1
130
32
23
18
12
10
10
5
4
3
117
Pentachlorophenol
in urine
(mg/liter)
Low
0.003
0.010
0.040
0.040
0.034
0.017
0.052
0.029
0.016
0.010
0.034
0.78
0.11
0.096
0.021
0.012
0.60
2.4
0.61
0.26
0.031
0.070
2.6
2.0
0.03
0.007
0.005
0.010
a
0.003
0.008
0.036
0.021
0.022
High
0.23
35.7
16.6
1.2
6.4
0.28
7.2
0.19
3.4
2.8
4.2
27.5
1.4
0.20
0.31
0.10
6.2
15.4
11.7
6.8
0.44
0.075
12.0
3.8
35.7
0.065
0.44
0.043
0.11
0.034
1.8
0.16
0.37
0.15
1.8
Mean
0.064
1.9
2.2
0.29
1.5
0.11
1.7
0.098
0.45
0.70
0.82
13.0
0.42
0.14
0.13
0.064
3.5
7.2
6.2
3.5
0.23
0.073
6.2
3.0
1.6
1.0
0.53
0.26
0.12
0.028
1.8
0.031
0.033
0.021
0.026
0.014
0.19
0.078
0.17
0.077
0.040
Not detected.
Source: Adapted from Revenue et al., 1967, Table I, pp. 322-323.
Reprinted by permission of the publisher.
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400
TABLE D.6.32. CONCENTRATION RANGE OF
PENTACHLOROPHENOL IN HUMAN URINE
Pentachlorophenol in urine
(yg/liter)
Persons sampled
Range of
— - . llCdLl
four replicates
General population
Carpenter
Boat builder
Sprayer
2.2-2.3
2.7-2.9
2.9-3.0
5.0-5.3
5.2-5.5
10.6-11.2
22.2-25.5
55.0-60.1
131-136
259-270
2.2
2.8
2.9
5.1
5.3
10.8
24.1
57.3
133
265
Source: Adapted from Cranmer and Freal, 1970,
Table III, p. 125.
exposed to pentachlorophenol. The clinical significance of this finding
is not known.
Recent data reported by Begley et al. (1977) indicate that chronic
exposure to pentachlorophenol may have reversible effects on kidney
function. Blood and urine samples from 18 male volunteers employed by a
firm which treated lumber and other wood products with 5% pentachloro-
phenol were used in determining levels and clearance values for creati-
nine, phosphorus, and pentachlorophenol before, at intervals during, and
following a 20-day vacation. Significant differences for blood and
urinary phosphorus levels and creatinine clearance were found before,
during, and after vacation. Begley et al. (1977) concluded that penta-
chlorophenol exposure results in decreased creatinine clearance and phos-
phorus reabsorption in the kidney and that the effects are reversible.
Spontaneous improvement was noted during the vacation interval.
Workers chronically exposed to pentachlorophenol demonstrated signif-
icantly elevated levels of total bilirubin and creatine phosphokinase,
although Takahashi et al. (1975) reported that the levels were within
normal limits. This study also indicated that workers chronically ex-
posed to pentachlorophenol showed a significantly higher prevalence of
gamma-mobility C-reactive protein in the sera. The clinical significance
of these elevated levels in persons exposed to pentachlorophenol is not
known. Takahashi et al. (1975) noted, however, that C-reactive protein
-------
401
levels are often elevated in acute states of various inflammatory dis-
orders or tissue damage. It was therefore inferred that the elevated
levels of C-reactive protein in individuals exposed to pentachlorophenol
indicate inflammation or tissue injury.
The greatest risk of pentachlorophenol exposure obviously exists
among those engaged in the manufacture and use of the compound. The
general population may be exposed to pentachlorophenol via atmospheric
contamination, the presence of pentachlorophenol in water and food, and
possible cutaneous contamination from pentachlorophenol-treated items.
No data are available on ambient levels of pentachlorophenol in the
atmosphere; therefore, pentachlorophenol uptake via the respiratory
route remains speculative.
Arsenault (1976) reported pentachlorophenol levels in air of com-
panies using pentachlorophenol as a wood preservative (Table D.6.33).
The average worker exposure was defined as the atmospheric concentration
found in the area where a worker spends the majority of his time and the
maximum worker exposure as that found in the maximum exposure area near
the pentachlorophenol source. Normal physiologic data indicate that a
person performing light work breathes approximately 4.8 m3 of air during
8 hr. The calculated total pentachlorophenol inhalation exposure would
range from 0.03 to 1.42 mg. For an individual doing moderately heavy
work for 8 hr, the approximate total pulmonary ventilation would be
14.4 m3 with pentachlorophenol inhalation exposures ranging from 0.08 to
4.28 mg. Humans normally excrete approximately 1.4 liters of urine per
day; thus, the total pentachlorophenol content in urine, as calculated
from the data in Table D.6.33, would range from 1.4 to 4.0 mg per person
per day. Based on these calculations, exposure and excretion are approxi-
mately balanced. Undoubtedly, there is also some dermal exposure, and
it is unlikely that there is 100% retention of inhaled pentachlorophenol.
TABLE D.6.33. PENTACHLOROPHENOL CONCENTRATIONS IN AIR FROM PLANTS
AND URINE OF MILL WORKERS IN OREGON
Type of
operation
Pentachlorophenol in air (mg/m3)
Average worker
exposure
Maximum worker
exposure
Pentachlorophenol
in urine
(mg/liter)
Dip
Spray
Pressure
Mean
0.019
0.006
0.014
Range
0.003-0.063
0.003-0.012
0.004-0.028
Mean
0.019
0.026
0.297
Range
0.006-0.063
0.004-0.069
0.043-1.000
Mean
2.83
0.98
1.24
Range
0.12-9.68
0.13-2.58
0.17-5.57
Source: Adapted from Arsenault, 1976, Table 1, p. 8. Reprinted by
permission of the publisher.
-------
402
A serious concern is the possible bioaccumulation of pentachloro-
phenol in adipose tissue. The chemical structure of the compound suggests
the possibility of accumulation in fat, and recent data have indicated
that this may occur. Apparently, pentachlorophenol accumulates in fish
(Section D.5.2.2.3). Pentachlorophenol has also been detected in human
adipose tissue. Autopsy results from an infant fatally poisoned by penta-
chlorophenol (Table D.6.6) showed a higher level of pentachlorophenol in
the fat than in any other tissue examined (Armstrong et al. , 1969). A
survey by Shafik (1973) indicated the presence of low levels of penta-
cfrlorophenol in adipose tissue samples from the general population.
Levels of 12 to 45 vg/kg were found in individuals not occupationally
exposed to the substance (Table D.6.34). Despite the detection of penta-
chlorophenol in fat tissue, no evidence presently indicates a signifi-
cant accumulation of pentachlorophenol in mammalian fat tissue. More
data are needed to fully resolve this question.
TABLE D.6.34. PENTACHLOROPHENOL LEVELS IN
ADIPOSE TISSUE OF NONOCCUPATIONALLY
EXPOSED PERSONS
(Ug/kg)
, Pentachlorophenol
Sample No. ,. ...
r in adipose tissue
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
17
52
45
23
25
21
35
17
20
22
14
35
52
24
12
12
29
Source: Adapted from Shafik, 1973,
Table 1, p. 62. Reprinted by permission of
the publisher.
D.6.2.2.5 Exposure, Safety, and Pentachlorophenol Intoxication —
Fatalities due to pentachlorophenol poisoning are about equally divided
between people poisoned by contact with pentachlorophenol and those
poisoned with sodium pentachlorophenate. In almost all cases, fatal and
nonfatal, misuse of the compound was paramount.
-------
403
A number of fatalities have occurred when sodium pentachlorophenate
was used as a molluscicide or as a herbicide. According to Blair (1961)
and Gordon (1956), the workers involved in the spraying operations were
inadequately protected from cutaneous contact with the spray.
Fatal poisonings by pentachlorophenol have also occurred in timber
dipping operations. In the cases reported by Truhaut, Boussemart, and
L'Epge (1952) and by Bergner, Constantinidis, and Martin (1965), the
workers were either dipping wood in preservative solutions or handling
newly treated lumber without gloves. Because pentachlorophenol can pass
through the skin without overt damage, considerable risk is involved in
handling the compound without the protection of gloves.
In the pentachlorophenol manufacturing industry, poisoning has
occurred in some cases because toxic levels of dust, aerosol, or vapor
build up in enclosed areas due to inadequate ventilation. Thus, poor
hygiene lies at the root of many of the poisonings. A study by Arsenault
(1976) illustrated the effect of good industrial hygiene in handling this
very hazardous compound. A review of the medical records of the 28 wood
preserving plants operated by the Koppers Company, which covered approxi-
mately 1670 employees over a ten-year span, revealed only 26 cases of
pentachlorophenol-related health problems (Table D.6.35).
Nonoccupationally exposed persons have also been involved in penta-
chlorophenol poisoning incidents. Two fatalities in a St. Louis nursery
apparently resulted from the improper use of a formulation containing
sodium pentachlorophenate in the laundering of diapers and infants' bed
linens (Robson et al., 1969). A California housewife suffered from
pentachlorophenol intoxication following the improper use of pentachloro-
phenol to prevent graying of the paneling inside her new home (Anonymous,
1970).
A series of papers by Duggan and Lipscomb (1969), Duggan and
Corneliussen (1972), and Manske and Corneliussen (1974) provide esti-
mates of the average dietary intake of various pesticide chemicals in the
United States. Pentachlorophenol was one of the chemicals studied, and
the composite data are shown in Tables D.6.36 and D.6.37. The major con-
clusion that can be drawn from these data is that pentachlorophenol is
occasionally present in food products. The levels found, although small,
represent a source of pentachlorophenol contamination for humans. In
areas where pentachlorophenol is widely used, food contamination may be
substantially higher than the values recorded.
Possible exposure may also occur via drinking water. Buhler,
Rasmusson, and Nakaue (1973) monitored pentachlorophenol levels in sewage
influent collected from three Oregon cities, the composite effluent from
the same sewage treatment plants, the Willamette River just upstream
from Corvallis, Oregon, and the drinking water processed at the Taylor
Water Treatment Plant in Corvallis (Tables D.6.38 and D.6.39 and Figure
D.6.19). Pentachlorphenol levels in the 24-hr composite samples of
sewage influent collected from the three Oregon cities ranged from 1 to
5 yg/liter. Composite effluent values ranged from 1 to 4 yg/liter,
-------
404
TABLE D.6.35. CASES OF PENTACHLOROPHENOL-
RELATED HEALTH PROBLEMS REPORTED BY
EMPLOYEES OF WOOD PRESERVING PLANTS
OPERATED BY THE KOPPERS COMPANY OVER
A TEN-YEAR PERIOD
Number
Health problem of cases
reported
Chemical conjunctivitis 12
Skin burns 9
Allergy 1
Dermatitis (arms and hands) 2
Miscellaneous 2
Total 26
One case of gastritis from inhalation
of pentachlorophenol and one case of folli-
culitis on legs from continually wearing
pentachlorophenol-contaminated trousers.
Source: Adapted from Arsenault, 1976,
p. 9. Reprinted by permission of the
publisher.
TABLE D.6.36. AVERAGE INCIDENCE AND DAILY INTAKE OF
PENTACHLOROPHENOL IN FOOD IN THE UNITED STATES
Year
1965
1966
1967
1968
1969
Number of Samples containing
composite pentachlorophenol
samples (%)
216
332
360
360
360
1.4
3.3
2.2
1.9
2.8
Average
daily intake
(mg per person)
<0.001
0.006
0.001
0.001
0.002
Source: Compiled from Duggan and Corneliussen, 1972.
-------
405
TABLE D.6.37. AVERAGE DAILY INTAKE OF PENTACHLOROPHENOL
FROM EIGHT FOOD CLASSES IN THE UNITED STATES
(mg per person)
Pentachlorophenol intake
Food
6/66-4/67 6/67-4/68 6/68-4/69 6/70-4/71
Beverages 0.001
Dairy products <0.001
Grains and cereals <0.001
Meat, fish, and poultry <0.001
Oils, fats, and shortening <0.001
Potatoes
Garden fruits
Sugars and adjuncts
0.001 0.001 <0.001
0.001 0.001
<0.001 0.001
<0.001
<0.001
<0.001
-------
TABLE D.6.38. LEVELS OF PENTACHLOROPHENOL IN 24-hr COMPOSITE INFLUENT AND EFFLUENT
SAMPLES AND TOTAL PENTACHLOROPHENOL OUTPUT FROM SEWAGE TREATMENT PLANTS IN OREGON
City
Corvallis
Eugene
Salem
Pentachlorophenol
level Pentachloropheno
Population (yg/liter) removed
f/\
Influent Effluent
38,000 1.4 1.0
60,000 4.1 3.3
80,000 4.6 4.4
\">f
28.6
19.5
4.4
Total pentachlorophenol
1 output
( /da ) ^ per 10>000
° people per day)
20 5.5
144 26.0
267 33.6
Source: Adapted from Buhler, Rasmusson, and Nakaue, 1973, Table IV, p. 932. Reprinted
by permission of the publisher.
-------
407
TABLE D.6.39. CONCENTRATION AND REMOVAL OF PENTACHLOROPHENOL AT VARIOUS
STAGES OF THE WATER TREATMENT PROCESS AT THE TAYLOR PLANT
IN CORVALLIS, OREGON
Stage sampled
Time
sampled
Pentachlorophenol
a concentration
(yg/liter)
Pentachlorophenol
removed
Raw Willamette River water
(influent)
At flocculation step
After sedimentation
After filtration (final
product)
8:00 AM
8:27 AM
10:05 AM
10:15 AM
0.17
0.06
0.04
0.06
65
76
65
a.
Sampling times were calculated on the basis of known volumes, delay
times, and a water flow of 25,350 liters/min pumped into the treatment plant.
Source: Adapted from Buhler, Rasmusson, and Nakaue, 1973, Table V,
p. 933. Reprinted by permission of the publisher.
ORNL-DWG 78-10536
0.6
O 0.4
UJ
a.
O
a:
O
I
O
0.2
UJ
Q.
I I
I I I I
6:OO 10:00 2:00
AM
6:00 10:00 2:00 6:00
PM
TIME
Figure D.6.19. Hourly concentrations of pentachlorophenol in the
Willamette River on September 30, 1969. Source: Adapted from Buhler,
Rasmusson, and Nakaue, 1973, Figure 2, p. 932. Reprinted by permission
of the publisher.
-------
408
reported levels of pentachlorophenol as high as 10 yg/liter in river water
in Japan (Figure D.6.20). In Japan pentachlorophenol is widely used as
a herbicide during rice transplantation. High pentachlorophenol levels
in water from the portion of a river downstream from a pulp mill were
reported by Rudling (1970).
One source of human contamination by pentachlorophenol which has
often been overlooked is the possible presence of the substance as a
degradation product of other compounds in the body. Preliminary evidence
from Yang, Coulston, and Goldberg (1975) suggested the possible formation
of pentachlorophenol in the rhesus monkey following administration of
hexachlorobenzene. Lui and Sweeney (1975) and Mehendale, Fields, and
Matthews (1975) isolated pentachlorophenol from the urine of rats dosed
with hexachlorobenzene; pentachlorophenol was not detected in the feces.
Mehendale, Fields, and Matthews (1975) also showed that microsomal prep-
arations from rat liver were able to produce one or more chlorophenols,
including pentachlorophenol. Karapally, Saha, and Lee (1973) used gas
chromatography to tentatively identify pentachlorophenol in the urine of
rabbits which had been administered a dose of 14C-labeled lindane
(Y-l,2,3,4,5,6-hexachlorocyclohexane). Engst, Macholz, and Kujawa (1976)
gave rats 8 mg hexachlorobenzene per kilogram for 19 days. Analysis of
the tissues revealed hexachlorobenzene and pentachlorophenol as the main
metabolite. Small amounts of 2,3,4,6- and 2,3,5,6-tetrachlorophenol,
2,4,6-trichlorophenol, and pentachlorobenzene were also detected. Engst
et al. (1976) also demonstrated that pentachlorophenol, tetrachlorophenols,
and trichlorophenols are metabolites of the insecticide lindane in the rat.
These studies offer an alternative explanation for the nearly ubiquitous
presence of pentachlorophenol in humans and question the tacit assumption
that pentachlorophenol in human urine, serum, and tissues results from ex-
posure to pentachlorophenol. Additional investigations to determine the
ORNL-OWG 76-10537
Figure D.6.20. Pentachlorophenol residues in river water in south-
western Japan during July 1969. Source: Adapted from Goto, 1971,
Figure 2, p. 109.
-------
409
extent of pentachlorophenol synthesis from other compounds present in
human tissues are urgently needed.
D.6.2.3 Carcinogenicity
Innes et al. (1969) found no significant indication of tumorigenic-
ity following oral administration of pentachlorophenol to mice. Schwetz
et al. (1978) fed rats pentachlorophenol in a lifetime study. No treat-
ment-related increase in tumors was found (Table D.6.40). Boutwell and
Bosch (1959) reported that repeated applications of phenol and some sub-
stituted phenols can promote the appearance of skin tumors in mice fol-
lowing a single initiating dose of dimethylbenzanthracene. Tumors also
developed in mice (not exposed to dimethylbenzanthracene) treated with
phenol alone for long periods. When pentachlorophenol was tested in a
similar system, tumorigenicity and tumor-promoting activity were absent.
Thus, no evidence exists that pentachlorophenol possesses carcinogenic
characteristics.
D.6.2.4 Teratogenicity
Pentachlorophenol does not appear to be teratogenic in the rat
(Schwetz, Keeler, and Gehring, 1974; Larsen et al., 1975). Although
some degree of malformation has been observed, the number was generally
minimal and could have been due to the toxic effects of the compound on
the maternal rat or, if placental transfer occurs, a direct fetotoxic
effect on the developing embryo. Following the administration of penta-
chlorophenol to rats, signs of embryotoxicity and fetotoxicity, such as
resorptions, subcutaneous edema, dilated ureters, and anomalies of the
skull, ribs, vertebrae, and sternebrae, were observed at an incidence
which increased with increasing doses. Larsen et al. (1975) indicated
that placental transfer of pentachlorophenol is minimal and that the
fetotoxic effects likely resulted from a direct effect on the maternal
rat. The most prominent effect of pentachlorophenol on the mammalian
system is hyperpyrexia, and this effect alone may be the cause of the
fetotoxicity. The no-effect level of pentachlorophenol in the rat has
been reported by Schwetz, Gehring, and Kociba (1973) to be 5 mg/kg body
weight per day. Hinkle (1973) administered 1.25 to 20 mg/kg on day 5 to
day 10 of gestation in Golden Syrian hamsters. Fetal deaths and/or
resorptions were observed in three of six tests groups (unspecified).
D.6.2.5 Mutagenicity
Pentachlorophenol did not exhibit mutagenic properties when tested
in a microbiological system (Anderson, Leighty, and Takahashi, 1972), in
a mammalian test system (Buselmaier, RShrborn, and Propping, 1973), or
in the fruit fly, Drosophila melanogaster (Vogel and Chandler, 1974).
-------
TABLE D.6.40. INCIDENCE OF PRIMARY TUMORS (BASED ON HISTOPATHOLOGICAL DIAGNOSIS)
IN RATS FED PENTACHLOROPHENOL FOR 22 MONTHS (MALES) AND 24 MONTHS (FEMALES)
Number
Number
Number
Number
with
of rats examined
of rats with tumors
of tumors
of tumors /rats
tumors
Number of morphologic
malignant tumors
0
mg/kg
27
11
17
1.6
1
1
mg/kg
26
13
14
1.1
3
Males
3
mg/kg
27
13
17
1.3
2
10
mg/kg
27
12
15
1.3
1
30
mg/kg
27
11
16
1.4
0
0
mg/kg
27
27
62
2.3
2
1
mg/kg
27
26
67
2.6
7
Females
3
mg/kg
27
25
42
1.7
2
10
mg/kg
27
25
63
2.5
3
30
mg/kg
27
25
63
2.5
2
Source: Adapted from Schwetz et al., 1978, Table 5, p. 307. Reprinted by permission of
the publisher.
-------
411
SECTION D.6
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32. Duggan, R. E., and P. E. Corneliussen. 1972. Dietary Intake of
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33. Duggan, R. E., and G. Q. Lipscomb. 1969. Dietary Intake of Pesticide
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34. Engst, R., R. M. Macholz, and M. Kujawa. 1976. The Metabolism of
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16:248-251.
35. Engst, R. , R. M. Macholz, M. Kujawa, H. J. Lewerenz, and R. Plass.
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36. Flickinger, C. W. 1971. Pentachlorophenol and Sodium Pentachloro-
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414
39. Gordon, D. 1956. How Dangerous Is Pentachlorophenol? Med. J. Aust.
2:485-488.
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pp. 105-110.
41. Haley, T. J. 1977. Human Poisoning with Pentachlorophenol and Its
Treatment. Ecotoxicol. Environ. Saf. 1:343-347.
42. Hanstein, W. G., and Y. Hatefi. 1974. Characterization and Localiza-
tion of Mitochondrial Uncoupler Binding Sites with an Uncoupler
Capable of Photoaffinity Labeling. J. Biol. Chem. 249(5):1356-1362.
43, Hinkle, D. K. 1973. Fetotoxic Effects of Pentachlorophenol in
Golden Syrian Hamster (abstract). Toxicol. Appl. Pharmacol.
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44. Hoben, H. J., S. A. Ching, and L. J. Casarett. 1976a. A Study of
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Inhalation Exposure System for High Doses in Short Exposure Time.
Bull. Environ. Contain. Toxicol. 15:86-92.
45. Hoben, H. J., S. A. Ching, and L. J. Casarett. 1976£>. A Study of
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46. Hoben, H. J., S. A. Ching, and L. J. Casarett. 1976e. A Study of
Inhalation of Pentachlorophenol by Rats: Part IV. Distribution and
Excretion of Inhaled Pentachlorophenol. Bull. Environ. Contam.
Toxicol. 15:466-474.
47. Hoben, H. J., S. A. Ching, L. J. Casarett, and R. A. Young. 1976.
A Study of the Inhalation of Pentachlorophenol by Rats: Part I.
A Method for the Determination of Pentachlorophenol in Rat Plasma,
Urine and Tissue and in Aerosol Samples. Bull. Environ. Contam.
Toxicol. 15:78-85.
48. Innes, J.R.M., B. M. Ulland, M. G. Valeric, L. Petrucelli, L. Pishbein,
E. R. Hart, A. J. Pallotta, R. R. Bates, H. L. Falk, J. J. Gart, M.
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Industrial Chemicals for Tumorigenicity in Mice: A Preliminary Note.
J. Natl. Cancer Inst. 42(6):1101-1114.
49. Ishak, M. M., A. A. Sharaf, and A. H. Mohamed. 1972. Studies on the
Mode of Action of Some Molluscicides on the Snail, Biomphataria
alexandrina: II. Inhibition of Succinate Oxidation by Bayluscide,
Sodium Pentachlorophenate, and Copper Sulphate. Comp. Gen. Pharmacol.
3(12):385-390.
-------
415
50. Jakobson, I., and S. Yllner. 1971. Metabolism of ^C-Pentachloro-
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52. Karapally, J. C., J. G. Saha, and Y. W. Lee. 1973. Metabolism of
Lindane-^C in the Rabbit: Ether-Soluble Urinary Metabolites. J.
Agric. Food Chem. 21(5):811-818.
53. Kehoe, R. A., W. Deiehmann-Gruebler, and K. V. Kitzmiller. 1939.
Toxic Effects upon Rabbits of Pentachlorophenol and Sodium Penta-
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54. Kimbrough, R. D. 1972. Toxicity of Chlorinated Hydrocarbons and
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55. Kimbrough, R. D., and R. E. Linder. 1975. The Effect of Technical
and 99% Pure Pentachlorophenol on the Rat Liver: Light Microscopy
and Ultrastructure (abstract). Toxicol. Appl. Pharmacol. 33:131-132.
56. Klemmer, H. W. 1972. Human Health and Pesticides — Community Pesti-
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57. Knudsen, I., H. G. Verschuuren, F. M. Den Tonkelaar, R. Kroes, and
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58. Kociba, R. J., P. J. Gehring, S. B. McCollister, C. E. Wade, R. W.
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60. Larsen, R. V., G. S. Born, W. V. Kessler, S. M. Shaw, and D. C. Van
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-------
416
63. McGavack, T. H., L. J. Boyd, F. V. Piccione, and R. Terranova.
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Fate of Pentachlorophenol in the Animal Organism. J. Ind. Hyg. Toxicol,
25 (5)-.192-194.
65. Manske, D. D. , and P. E. Corneliussen. 1974. Pesticide Residues in
Total Diet Samples (VII). Pestic. Monit. J. 8(2):110-124.
66. Mason, M. F., S. M. Wallace, E. Foerster, and W. Drummond. 1965.
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67. Mehendale, H. M., M. Fields, and H. B. Matthews. 1975. Metabolism
and Effects of Hexachlorobenzene on Hepatic Microsomal Enzymes in
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68. Menon, J. A. 1958. Tropical Hazards Associated with the Use of
Pentachlorophenol. Br. Med. J. 1(5030):1156-1158.
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Clinical Examination of Workers Exposed to Pentachlorophenol. Rodo
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Tetrachlorophenol. South Med. J. 56:632-634.
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Tissues and Water. Water Res. 4:533-537.
75. Schwetz, B. A., P- J. Gehring, and R. J. Kociba. 1973. Toxicological
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417
77. Schwetz, B. A., J. F. Quast, C. G. Humiston, C. E. Wade, G. C. Jersey,
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78. Schwetz, B. A., J. F. Quast, P. A. Keeler, C. G. Humiston, and R. J.
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79. Shafik, T. M. 1973. The Determination of Pentachlorophenol and
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-------
418
89. Yang, R.S.H., F. Coulston, and L. Goldberg. 1975. Chromatographic
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D.7 ENVIRONMENTAL DISTRIBUTION AND TRANSFORMATION
D.7.1 TRENDS IN PRODUCTION AND USE
Pentachlorophenol and sodium pentachlorophenate have been used ex-
tensively as broad-spectrum biocides. In 1972, annual production in the
United States alone exceeded 50,000,000 Ib (23,000,000 kg) (Anonymous,
1972). Growth was projected at about 4% per annum after 1972. Estimated
production of pentachlorophenol and sodium pentachlorophenate in 1976 was
56,000,000 Ib (25,400,000 kg). About 90% to 95% of this amount is used
in the wood preservation industry. The remaining 5% to 10% has a large
number of applications in industry and agriculture.
Pentachlorophenol (or sodium pentachlorophenate) has been used as a
wood preservative to control mold and termite infestations, as a weedicide
or preharvest desiccant, as an algicide, as a molluscicide for the eradica-
tion of the snail which serves as intermediate host for the human schisto-
somes, and in food processing plants and pulp mills for the control of
slime and mold. Pentachlorophenol and sodium pentachlorophenate also have
been used as fungicides and/or bactericides in the processing of cellulosic
products, starches, adhesives, paints, leathers, oils, rubber, textiles,
and wooden crates used for packaging raw agricultural products. Obviously,
a product with such wide and varied uses has a serious potential for envi-
ronmental contamination (Bevenue and Beckman, 1967).
Pentachlorophenol has been manufactured by five chemical companies
in five states. The locations and production capacities of these companies
are given in Table D.7.1. Recently, Sonford Chemical Company and Monsanto
Industrial Chemicals Company terminated production or indicated an intent
to stop production. Pentachlorophenol is produced in widely separated
states. Unlike some agricultural pesticides which are restricted to an
area of intense application, pentachlorophenol is widely used as an indus-
trial preservative; thus, the logistics of distribution require that it
be produced at scattered locations.
The potential for pollution of the environment by pentachlorophenol
obviously exists at point sources of pollution such as industries that
manufacture or use the compound in large amounts. The widespread use of
the compound in the environment as a wood preservative and as a general
biocide also allows for environmental contamination through leaching from
preservative-treated wood; direct contamination of soil, air, and water
when the compound is used as a weedicide; and release of the compound
from preservative-treated items either during use or after disposal.
D.7.2 SOURCES OF POLLUTION
D.7.2.1 Distribution in Air
Information on atmospheric .levels of pentachlorophenol is scanty.
Casarett et al. (1969) conducted a survey of blood and urine pentachloro-
phenol concentrations among workers employed by a factory involved in wood
419
-------
TABLE D.7.1. PRODUCERS OF PENTACHLOROPHENOL IN THE UNITED STATES
Annual
Company and location
Dow Chemical Company, Midland, Michigan
Monsanto Industrial Chemicals Company,
Sauget, Illinois
Reichhold Chemicals, Inc.
Sonford Chemical Company,
Vulcan Materials Company,
Total
, Tacoma, Washington
Houston, Texas
Wichita, Kansas
pentachlorophenol
production capacity
(Ib x 106)
18
26
16
18
19
97
(kg x 106)
8.1
11.8
7.2
8.1
8.6
43.8
Estimated
pentachlorophenol
production, 1974
(Ib x 106)
5
10
10
5.2
18.7
48.9
(kg x 106)
2.2
4.4
4.4
2.3
8.4
21.7
ro
o
Source: Adapted from Ifeadi, 1975, Table 10, p. 45.
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421
preservation. This survey indicated substantial pentachlorophenol con-
tent in blood and urine compared with that of nonoccupationally exposed
persons; qualitatively significant concentrations of pentachlorophenol
were detected in the plant atmosphere. Because of widespread pentachloro-
phenol distribution in the factory yard, the workers were believed, in
part, to have received respiratory intoxication. Revenue et al. (1967)
found substantial pentachlorophenol levels in the urine of nonoccupational-
ly exposed persons in Hawaii. Although the source was uncertain, Casarett
et al. (1969) suggested that respiratory tract absorption was a reasonable
explanation for the nearly ubiquitous occurrence of pentachlorophenol in
the urine of Hawaiians. Pentachlorophenol is used widely in Hawaii to
protect wooden structures against termite infestation, and therefore low-
level pentachlorophenol contamination of the atmosphere is a likely possi-
bility. No direct data on ambient pentachlorophenol levels in the atmosphere
are available. Circumstantial evidence was provided by Bevenue, Ogata, and
Hylin (1972), who found levels of pentachlorophenol in rainwater collected
in Hawaii ranging from 2 to 284 ng/liter (Table D.7.2). The pentachloro-
phenol in the rainwater likely came from washout of pentachlorophenol
present in the atmosphere either as a vapor or as an occlusion on dust
particles. These authors also found 14 ng pentachlorophenol per liter
TABLE D.7.2.
PENTACHLOROPHENOL IN RAINWATER, OAHU, HAWAII,
1971-1972
Sampling site
Kailua
Kaneohe
Waipahu
Honolulu
Nuuanu-Vinyard Avenues
Nuuanu-School Streets
Nuuanu-School Streets
Nuuanu-School Streets
Pawaa Lane
Pawaa Lane
Manoa
Manoa
Pentachlorophenol
Period content
(ng/liter)
1-5-72 to 1-23-72
9-30-71 to 11-17-71
1-4-72 to 1-25-72
1-28-72 to 2-23-72
2-28-72 to 3-4-72
3-4-72 to 4-27-72
1-6-72 to 3-4-72
1-6-72 to 3-4-72
9-28-71 to 12-27-71
1-1-72 to 2-23-72
2-25-72 to 5-15-72
1-1-72 to 2-20-72
2-27-72 to 5-11-72
9-30-71 to 11-15-71
1-3-72 to 1-24-72
20
8
11
16
15
10
14
16
77
45
2
55
50
284
270
Source: Adapted from Bevenue, Ogata, and Hylin, 1972, Table 1,
239. Reprinted by permission of the publisher.
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422
in snow samples from Mauna Kea Summit and 10 ng/liter in water from Lake
Waiau, which is fed almost exclusively by the summit snows.
Airborne pentachlorophenol may be toxic to conifer seedlings
(Ferguson, 1959). The damage noted to plants grown in flats treated with
pentachlorophenol apparently resulted from volatilization of the compound.
Pentachlorophenol vapor is also toxic to man. Treatment of the interior
redwood paneling of a home resulted in intoxication of the inhabitant,
presumably by volatilization of pentachlorophenol from the paneling
(Anonymous, 1970). Thus, potential exists for volatilization of penta-
chlorophenol from preservative-treated objects, thereby increasing the
pentachlorophenol levels in the air. However, the low vapor pressure of
pentachlorophenol (0.00011 mm Hg at 20°C) suggests that volatilization
is a slow process. Furthermore, the use of oils and other hydrocarbon
solvents further reduces volatilization. Intuitively, if pentachloro-
phenol vaporized very rapidly from treated wood, where 90% of pentachlo-
rophenol is used, then its use as a wood preservative would be very limited
(Environmental Health Advisory Committee, 1978; Thompson, McGinnis, and
Ingram, 1978).
Pentachlorophenol may volatilize from soil or water. Hilton, Yuen,
and Nomura (1970) attributed a pronounced decrease in the pentachlorophenol
content of an aerated solution to volatilization. Volatilization from
water may be a significant source of atmospheric pentachlorophenol, espe-
cially in areas where it is applied as a herbicide in paddy fields or used
as a molluscicide. Adsorption to soil is discussed in Section D.2.5.3,
but no data are available for an evaluation of pentachlorophenol losses
from soil by volatilization. Research in this area is warranted.
D.7.2.1.1 Point Sources — The potential for emission of large quan-
tities of pentachlorophenol into the atmosphere exists in factories where
pentachlorophenol is manufactured or used widely. Factories using high
pressures and temperatures for wood preservation possess the potential
for widespread distribution of pentachlorophenol into the atmosphere.
No information on pollution control of atmospheric emissions by the wood
preserving industry was found. A survey was made by Ifeadi (1975) in an
attempt to develop background information on air pollution from pesticide
manufacturing factories. This information, compiled from published data
and "scanty responses from the pesticide manufacturers," was used to
determine the efficiency of pollution control methods and the rates of
emission for various compounds during the manufacture of pentachlorophenol
(Table D.7.3). No site visits or samplings were made. Following treat-
ment of gaseous emissions with a scrubber, the emission of pentachloro-
phenol amounted to 4.32 Ib/ton (2.16 kg/metric ton) of pentachlorophenol
manufactured. Thus, based on a nationwide production of 23,000,000 kg
per year, about 50,000 kg is emitted. Because these values were not veri-
fied by plant visits and samplings, these figures may be in error. Ifeadi
(1975) noted that the control of particulate emission by using bag filters
is inefficient and needs augmentation. Controlled emission at this stage
of manufacture is reported as 0.55 kg/metric ton. Based on an annual
production for a single plant of 5,000,000 kg pentachlorophenol, approxi-
mately 2750 kg would be emitted in the particulate form. The effect of
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423
TABLE D.7.3. AIR CONTAMINANT CONTROL METHODS USED IN
PENTACHLOROPHENOL MANUFACTURE
vcf • Controlled emission
Control method ,,.^ •*
\7o)
(lb/ton) (kg/metric ton)
Wet-packed and venturi
scrubber (with water) 99-100 . 4.32a 2.16
Dust collector (bag filters)
At ingot casting
At shotting operation
99
95
•t
0 . lr 0 . 05
1*> 0.5
Controlled emission reported by Monsanto Industrial Chemicals Com-
pany based on 1974 production.
^Controlled emission reported by Reichhold Chemicals, Inc., based on
1974 production.
Source: Adapted from Ifeadi, 1975, Table 12, p. 52.
this quantity of a compound which is potentially as toxic as pentachloro-
phenol on the immediate environment surrounding the factory is not known.
Furthermore, because figures supplied to Ifeadi (1975) did not include
efficiency data on air contaminant control from three of the five chemical
firms involved in manufacturing pentachlorophenol, these levels must be
considered a lower limit. Firms not reporting efficiency data may be
releasing large quantities to the atmosphere. Because of the known toxic
effects of airborne pentachlorophenol as well as the ability of penta-
chlorophenol to bioaccumulate in aquatic organisms, a detailed evaluation
of the amounts discharged to the atmosphere is needed. The effects of
nonlethal amounts of pentachlorophenol in the atmosphere on man and the
environment have not been adequately assessed.
D.7.2.1.2 Nonpoint Sources - Because of the total lack of atmospheric
monitoring information, the prime sources of nonpoint pollution are only
speculative. Likely sources of atmospheric pollution with pentachloro-
phenol include volatilization from water, soil, impervious surfaces, and
pentachlorophenol-treated obj ects.
D.7.2.2 Distribution in Aquatic Environments
D.7.2.2.1 Point Sources - Point sources for pentachlorophenol pollu-
tion of water are of two basic types: (1) factories which manufacture
pentachlorophenol or use it in wood treatment or slime control and (2)
municipal discharge from sewage treatment plants. Substantial levels of
pentachlorophenol have been found in effluents from some municipal sewage
treatment plants (Buhler, Rasmusson, and Nakaue, 1973).
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424
Large amounts of pentachlorophenol discharged into receiving water-
ways when spills or industrial accidents occur have a lethal effect on
aquatic organisms. In many cases, storm runoff carries pentachlorophenol
to receiving waterways from industrial sites where large quantities of
pentachlorophenol or pentachlorophenol-treated lumber are stored. Follow-
ing a heavy rain, Bevenue et al. (1972) detected 1.14 yg/liter pentachlo-
rophenol in a ditch which drained the grounds of a wood treatment plant.
A large pile of pentachlorophenol-treated lumber drenched by the rain was
believed to be the source of pentachlorophenol detected in the drainage
ditch. Thompson and Dust (1971) analyzed raw wastewater from five wood
treatment plants using pentachlorophenol and creosote. The pentachloro-
phenol content of the untreated wastewaters from these plants ranged from
25 to 150 mg/liter. Sewage treatment reduced these levels substantially
(Section D.7.4). Fountaine, Joshipura, and Keliher (1976) reported levels
of 0.1 to 10 ppm pentachlorophenol in water taken from a stream at various
distances from the outflow of a wood preserving company.
Pierce et al. (1977) determined pentachlorophenol residues in water,
fish, leaf litter, and lake sediment for 17 months after pentachlorophenol
contamination of a stream leading into a 15-ha man-made lake. A fish kill
occurred immediately after the spill. Water samples taken 2 to 17 months
after the spill contained 6 to 19 yg/liter pentachlorophenol. Pentachloro-
phenol levels in water increased after heavy rainfall, indicating contin-
uous influx from contaminated watershed areas. Pentachlorophenol levels
in sediment ranged from 2 to 1300 yg/kg, with levels decreasing with time.
Residues in fish decreased from 2.5 mg/kg to trace levels with 10 months.
Levels in fish increased to 0.65 mg/kg following the period of heavy rain-
fall and recontamination and then decreased to trace levels in 6 months.
The contribution of municipal chlorination to pentachlorophenol
levels in water supplies is unclear. Dougherty (1975, as cited by
Arsenault, 1976) found 0.1 yg/liter pentachlorophenol in the Tallahassee,
Florida, water supply. The source was not discussed, but it may have
resulted from municipal chlorination of drinking water and subsequent
chlorination of phenol to pentachlorophenol. Arsenault (1976) demon-
strated that 10 mg/liter chlorine is capable of chlorinating 1 mg/liter
phenol (from natural sources), yielding approximately 0.2 yg/liter penta-
chlorophenol. Considerable evidence indicates chlorination results in
the formation of the lower chlorinated phenols, but the report by Arsenault
(1976) is the only one suggesting that pentachlorophenol is generated by
municipal chlorination.
Bevenue et al. (1972) studied pentachlorophenol levels in the Sand
Island outfall in Hawaii. This sewage outfall, which receives all sewage
from the Honolulu area, contained 2.6 yg/liter pentachlorophenol in a
24-hr composite discharge. It is not known whether the sewage effluent
was treated prior to discharge.
Buhler, Rasmusson, and Nakaue (1973) found that pentachlorophenol
levels in 24-hr composite samples of sewage effluent collected simultane-
ously from three Oregon cities ranged between 1 and 4 yg/liter. Water
samples from the Willamette River contained between 0.10 and 0.70 yg/liter.
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425
Significant concentrations of pentachlorophenol were found in water treated
at the Taylor Water Treatment Plant in Corvallis; 0.3 lag/liter pentachloro-
phenol of unknown source was found in the treated drinking water. The
pentachlorophenol concentrations in the Willamette River were at least
ten times greater than calculated values derived by assuming that the
only source of pentachlorophenol was municipal sewage. Industrial sources
could be responsible for this discrepancy.
D.7.2.2.2 Nonpoint Sources — The diverse nonpoint sources of penta-
chlorophenol in water can be divided into two general types: (1) penta-
chlorophenol pollution of the environment over wide areas, such as use
of molluscicides for the control of snail populations, algicides, preemer-
gence herbicides, or defoliants for cotton and soybeans (Higginbotham,
Ress, and Rocke, 1970), and (2) leaching from objects treated with penta-
chlorophenol for preservative purposes (e.g., bactericides or fungicides).
In the absence of microbiological breakdown of the compound, pentachloro-
phenol-treated lumber may be a continuing nonpoint source of pollution.
Because pentachlorophenol is widely used in urban and industrialized
areas, this nonpoint source may become a point source if it reaches storm
sewers and is discharged into a stream.
The contribution of nonpoint pollution to the total environmental
load is difficult to assess. Pentachlorophenol has limited use in the
United States as a herbicide, molluscicide, and algicide, but in other
countries pentachlorophenol use has continued unabated. Death of wild-
life in Surinam (Vermeer et al., 1974) was attributed to the use of penta-
chlorophenol as a molluscicide in the rice fields (Section D.5.1.2.2.3).
Fish kills have been reported in Korea (Shim and Self, 1973) and Japan
(Nitta, 1972) as a result of pentachlorophenol use in rice fields (Section
D.5.2.2.3). Thus, widespread pentachlorophenol contamination can result
in serious environmental hazards. Vermeer et al. (1974) suggested that
the use of pentachlorophenol as a molluscicide should be reexamined and
perhaps banned because of its toxicity to wildlife.
Substantial levels of pentachlorophenol have been found in the rivers
of Japan (Goto, 1971). Residues in river water in southwestern Japan
ranged from 0.01 to 10 yg/liter in July 1969 (Section D.6.2.2.5). Goto
(1971) stated that these concentrations are not ecologically dangerous,
but this opinion is questionable, particularly when one considers the
evidence that pentachlorophenol may bioaccumulate in aquatic organisms.
Zitko, Hutzinger, and Choi (1974) surveyed pentachlorophenol levels in
the aquatic fauna in New Brunswick, Canada (Table D.7.4). Although the
levels were not toxicologically significant, detectable amounts were found
in aquatic fauna from "a relatively clean area." The source was unclear.
D.7.2.3 Distribution in Soil
Ambient pentachlorophenol levels in soil are not available. Penta-
chlorophenol is resistant to degradation, and a persistence ranging from
two weeks to one year has been reported (Section D.7.3.3). In general,
the assumption is made that when pentachlorophenol is applied to land as
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426
TABLE D.7.4. CONCENTRATION OF PENTACHLOROPHENOL IN
AQUATIC FAUNA AND COMMERCIAL FISH FOOD IN
NEW BRUNSWICK, CANADA
Pentachlorophenol
Sample content
(ng/g wet wt)
Cod 0.82
Winter flounder 1.77
3.99
Sea raven <0.5
Silver hake 1.75
Atlantic salmon 1.26
0.54
White shark liver 10.83
Double-crested cormorant egg 0.36
Herring gull egg 0.51
Fish food 2.23
Source: Adapted from Zitko, Hutzinger, and Choi,
1974, Table 1, p. 651. Reprinted by permission of
the publisher.
a herbicide or desiccant, the initial level of pentachlorophenol equals
the amount applied.
Because pentachlorophenol is a synthetic molecule with no known bio-
logical function under normal conditions, it is reasonable to assume that
the presence of pentachlorophenol in soil results from man's activities.
An exception to this assumption is the production of pentachlorophenol
as a metabolic product of other substances. The formation of pentachloro-
phenol from hexachlorobenzene has been suggested in the monkey and the
rat, and pentachlorophenol has been detected in rabbit urine following
the administration of lindane (Y-l,2,3,4,5,6-hexachlorocyclohexane)
(Section D.6.2.2.5). Lu and Metcalf (1975) confirmed the formation of
pentachlorophenol in a model aquatic ecosystem following the administra-
tion of hexachlorobenzene (Section D.5.2.1.3).
D.7.3 ENVIRONMENTAL FATE
Pentachlorophenol is an organic molecule and its ultimate fate under
aerobic conditions should be degradation to chlorine, carbon dioxide, and
water; anaerobically, several products are possible. An evaluation of
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427
the chemical properties of the compound (Section D.2) and monitoring infor-
mation would place the compound in the category of persistent compounds;
however, under appropriate conditions, pentachlorophenol is biodegradable.
Conditions promoting pentachlorophenol degradation in the environment and
in model laboratory systems are discussed in this section.
D.7.3.1 Mobility and Persistence in Air
Only limited data are available on the mobility and persistence of
pentachlorophenol in air. It may reach levels which are toxic to humans,
animals, and plants (Ferguson, 1959; Plakhova, 1966; Anonymous, 1970).
Toxic effects in greenhouse experiments indicate that pentachlorophenol
was carried by air (Ferguson, 1959). Information on the transport and
persistence of pentachlorophenol volatilizing from treated objects is not
available. Substantial levels of pentachlorophenol are present in rain-
water in areas where pentachlorophenol is widely used (Revenue, Ogata,
and Hylin, 1972). The prime mechanism of removal of pentachlorophenol
from the atmosphere is likely to be washout during precipitation.
D.7.3.2 Mobility and Persistence in Aquatic Environments
Pentachlorophenol (and/or sodium pentachlorophenate) may be present
in aquatic environments in one (or more) of the following forms: (1)
dissolved in either free or complexed form, (2) sorbed to suspended and/or
bottom sediments, or (3) carried in biological tissues. Movement of penta-
chlorophenol in water depends primarily on hydrological factors such as
currents and, in the case of transportation by organisms, movement and
migration of the organism. In studies with DDT, Vind, Muraoka, and
Mathews (1973) showed that the water-insoluble, organochlorine insecticides
may be transported in seawater primarily by absorption in the fatty cell
membranes of microorganisms. The extent of pentachlorophenol mobility due
to transportation by aquatic organisms warrants further intensive
investigation.
The persistence of pentachlorophenol in aquatic environments depends
on several environmental variables, but the interrelationships have not
been fully characterized. Pentachlorophenol may be effectively removed
from the aqueous phase by (1) volatilization into the atmosphere, (2)
photoinactivation, (3) adsorption, or (4) biodegradation. Hilton, Yuen,
and Nomura (1970) demonstrated in laboratory experiments that the penta-
chlorophenol content of aerated solutions decreases rapidly, presumably by
volatilization. The contribution of this phenomenon to pentachlorophenol
removal from water is unclear. In general, decomposition of pentachloro-
phenol in clear, shallow-water areas is rapid; longer persistence times
are seen in deep, turbid waters. Adsorption to sediments is an important
factor in pentachlorophenol removal from water (Section D.2.5.3). Decom-
position of pentachlorophenol in aqueous solutions has been demonstrated
under laboratory conditions with suitably activated microbial populations
(Section D.7.3.5). In the laboratory, microorganisms contained in acti-
vated sludge derived from sewage treatment plants exposed to pentachloro-
phenol are capable of degrading pentachlorophenol; however, the ubiquity
of these microorganisms in the environment remains an open question.
-------
428
Interactions among pentachlorophenol, soil, and water are made com-
plex by many variables. The system has been simplified in experimental
studies by maintaining some of the factors at a constant level. However,
some variables such as microbial activity, photodecomposition, volatility,
adsorption-desorption equilibria, soil pH, organic matter in soils, and
lateral movement by water are difficult, if not impossible, to control.
The interactions among these variables as they relate to pentachlorophenol
decomposition in a particular situation have not been quantified. Fur-
thermore, pentachlorophenol may be transported by organisms in the water.
Under certain specific conditions, pentachlorophenol levels in water
declined to negligible amounts in 48 hr (Bevenue and Beckman, 1967), but
other experiments indicated that substantial amounts of pentachlorophenol
may remain in a laboratory system for more than 120 days (Strufe, 1968).
Thus, depending on environmental conditions, pentachlorophenol may degrade
rapidly and pose little or no environmental hazard, or it may have marked
longevity and thereby pose a potential hazard of indeterminate proportions.
Increased emphasis should be placed on isolating the factors primarily
responsible for controlling the fate and longevity of pentachlorophenol
in various segments of the environment.
D.7.3.3 Mobility and Persistence in Soil
The mobility and persistence of pentachlorophenol in soils depend on
the physical and chemical characteristics of the soil as well as the pre-
vailing microbiological population. The effect of soil characteristics
on the mobility and persistence of pentachlorophenol have been discussed
previously (Section D.2.5.3). Because these same factors control the rate
of biological degradation of pentachlorophenol, they are also reviewed in
this section.
The mobility of pentachlorophenol in soils is affected by complex
environmental variables such as soil characteristics and climate. The
degree of mobility depends to a large extent on the tenacity with which
the compound is adsorbed by soil particles (Section D.2.5.3). The per-
sistence of pentachlorophenol has been correlated with many factors,
including soil temperature, moisture content, soil type, content of
organic matter and free iron oxides, type and content of clay minerals,
sorptivity, and cation-exchange capacity. The complex interrelationships
among these factors preclude an accurate prediction of the rate of penta-
chlorophenol degradation in various segments of the environment, although
pentachlorophenol degradation studies have been conducted under laboratory
conditions. Some general conclusions can be obtained from the literature.
Loustalot and Ferrer (1950) determined that the degree of pentachlo-
rophenol inactivation (to corn and cucumbers) increases with increased
temperature. Pentachlorophenol vaporizes from treated wood, producing a
toxic effect on nursery seedlings grown in close proximity (Ferguson,
1959). The effect of temperature on the vaporization of pentachlorophenol
from soil has not been studied; however, vaporization is a likely mechanism
for its dissipation from soil, and high temperature may contribute to in-
creased vaporization.
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429
The moisture content of soil also appears to affect the degradation
rate. Young and Carroll (1951) noted that pentachlorophenol degradation
was optimum when the moisture content of the soil approximated the mois-
ture equivalent. Kuwatsuka and Igarashi (1975) reported that degradation
of pentachlorophenol was faster under flooded conditions (250% water con-
tent) than under upland conditions (60% water content). Loustalot and
Ferrer (1950) studied the degradation of pentachlorophenol in fertile,
sandy loam and found that sodium pentachlorophenate was relatively stable
in air-dried soil, persisted for two months in soil with moderate mois-
ture content, and persisted for one month in water-saturated soil.
Soil composition has a marked effect on persistence of pentachloro-
phenol. Loustalot and Ferrer (1950) reported that pentachlorophenol per-
sisted longer in heavy clay than in sandy or sandy clay soils. Kuwatsuka
and Igarashi (1975) found a significant positive correlation between the
pentachlorophenol degradation rate and the organic matter content of the
soil. No degradation occurred in subsoil samples from forested areas
after 50 days of incubation. Kuwatsuka and Igarashi (1975) also corre-
lated rate of degradation with clay mineral composition, free-iron con-
tent, phosphate absorption coefficients, and cation-exchange capacity of
the soil; a lower level of probability was found with these variables
than with organic matter. Little or no correlation was found between
degradation and soil texture, clay content, degree of base saturation,
soil pH, or available phosphorus content (Table D.7.5).
Microbiological activity plays a primary role in the degradation of
pentachlorophenol in soil. Young and Carroll (1951) stated that penta-
chlorophenol decays more rapidly when the ambient temperature approaches
the optimal value for microbiological activity, indicating that a micro-
biological mechanism for degradation exists. They also demonstrated that
decomposition occurred more rapidly in soils with high organic matter
content. Ide et al. (1972) found no decay in sterilized soil samples.
The significant and positive correlation between organic matter content
and pentachlorophenol degradation as well as the fact that degradation
did not occur over a 50-day period in a forest subsoil sample devoid of
organic matter led Kuwatsuka and Igarashi (1975) also to suggest that
microorganisms play an important role.
Conversely, Ide et al. (1972) found that pentachlorophenol degraded
faster in an immature paddy soil with low organic matter content than in
an immature paddy soil with high organic matter content. Mature paddy
soils may contain microbiological populations which are acclimated to
pentachlorophenol as a result of its regular use in rice fields, which
would explain the discrepancy between these findings and those of
Kuwatsuka and Igarashi (1975). Kuwatsuka and Igarashi (1975) studied
widely different soils from flooded and upland areas of Japan. In the
laboratory, pentachlorophenol degraded most rapidly when upland soils
were maintained in an aerated condition. When the soils were flooded,
the rate decreased. In soil samples from flooded areas, pentachlorophe-
nol degraded most rapidly in the flooded state and at a slower rate under
aerated conditions. Thus, pentachlorophenol-degrading microorganisms
present in upland or paddy soils survived transfer to the laboratory and
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430
TABLE D.7.5. SIMPLE CORRELATION COEFFICIENTS RELATING DEGRADATION RATE
OF PENTACHLOROPHENOL TO PROPERTIES OF SOILS'2
Soil property
Total carbon content
Clay content
Cation-exchange
capacity
Available phosphorus
content
Free iron content
pH (H20)
Phosphate absorption
coefficient
Total carbon content
Clay content
Correlation coefficient
5
0.
0.
0.
0.
0.
0.
0.
0.
0.
days
Flooded
839*
182
831
392
889*
392
877*
Upland
^
817"
046
10
days
after incubation
20
days
for
30
days
conditions
0
0
o
0
0
0
0
.815*
.457
.574*
.365
.633^
.630d
.730*
0
0
0
0
0
0
0
.625"
.352
.599*
.499*
.858*
.420
.908*
0
0
0
0
0
0
0
.827*
.432
.525*
.589*
.409
.432
.922*
conditions
0
0
.814^
.264
0
0
.539*
.194
0
.383
0.152
Cation-exchange
capacity
Available phosphorus
0.926
0.763
0.368
0.333
content
Free iron content
pH (H20)
Phosphate absorption
coefficient
Deer aria t inn rat-t
0.675
0.091
0.184
0.937*
applied amount
0.642
0.597
0.539
0.821C
— residual
0.144
0.358
0.444
0.368
amount
0.198
0.387
0.153
0.253
1
2, ° ~ applied amount """ incubation period
^Significant at the 0.1% level of probability.
^Significant at the 1% level of probability.
Significant at the 5% level of probability.
Source: Adapted from Kuwatsuka and Igarashi, 1975, Table 2, p. 410.
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431
were most active when placed in environments to which they were adapted.
Alternatively, pentachlorophenol may be degraded by the several bacterial
species capable of surviving in either upland or flooded conditions.
The persistence of pentachlorophenol in soil is summarized in Table
D.7.6. The time ranges from 21 days to several hundred days; thus, penta-
chlorophenol is moderately persistent under some conditions and more per-
sistent under others. A moderate to high organic matter content and an
acclimated microbial population facilitate pentachlorophenol decomposition
in soil. Under conditions unfavorable for bacterial growth, degradation
is extremely slow.
D.7.3.4 Mobility and Persistence in Treated Wood
Little information is available on the mobility and persistence of
pentachlorophenol in preservative-treated items other than wood. Wood
preservation accounts for most of the pentachlorophenol use in the United
States; therefore, its fate and persistence in treated wood is of major
importance. Environmental contamination from other lesser uses have been
largely ignored. The mechanism of pentachlorophenol depletion from treated
wood has been studied extensively. Dissipation from and migration within
the wood depend on many factors such as the type of wood and its moisture
content, the solvent accompanying the pentachlorophenol, the treatment
process, and the soil conditions and climate where the wood is used
(Arsenault, 1970; Leutritz, 1971; Walters and Arsenault, 1971; Gjovik,
Bendtsen, and Roth, 1972). Information on these factors is useful in
determining the optimum conditions for maximum longevity of the wood,
but it provides little insight into the environmental impact of penta-
chlorophenol-treated wood.
Because pentachlorophenol is a very effective wood preservative,
it can be inferred that pentachlorophenol dissipation is not substantial
when wood is treated properly. Maximum retention of the preservative is
a primary characteristic of its effectiveness. Utility poles treated
with pentachlorophenol survived for 25 years without substantial decay
(Arsenault, 1970). Arsenault (1976) stated, "The fact that PCP-oil
solution moves down the pole towards the groundline is well established.
In the case of an occasional bleeding pole, the groundline and adjoining
soil can get saturated with PCP-oil solution. Therefore, it is reasonable
to ask what are the environmental effects of this migration. Generally
speaking, the vast majority of the poles in service have vegetation grow-
ing adjacent to the pole surface indicating no significant environmental
effect; PCP is an effective herbicide, being phytotoxic. We have shown
that PCP and the OCDD (octachlorodibenzo-p-dioxin) are both biodegraded
by soil if any soil contamination does occur. There is no significant
migration through the soil." The pentachlorophenol content of soil adja-
cent to treated utility poles was determined by Arsenault (1976). Soil
samples were taken at various distances from treated utility poles and
to depths of 6 in. at the base of 30 treated poles in six widely scattered
locations in the United States (Table D.7.7). Soil at 1 in. from the
poles contained an average pentachlorophenol content of 658 mg/kg; the
highest value found was 9500 mg/kg. Twelve inches from the treated poles
-------
TABLE D.7.6. PERSISTENCE OF PENTACHLOROPHENOL IN SOIL
Degradation
parameter
Soil type
Conditions
Time
Source
90% degradation
98% degradation
Arable layer in
rice fields (11
soils)
Forest red-yellow
soil sublayer
Wooster silt loam
Mature paddy soil
Permeable soil
Complete degradation Dunkirk silt loam
Effect on growth of
corn and cucumbers
Paddy soil
Fertile sandy
loam
60% water
250% water
60% water
250% water
7.5 kg/ha pentachlo-
rophenol, optimum
conditions for
microbial growth
Low organic content
Composted with sludge
from wood-treating
plant
Aerated, aqueous soil
suspension
Soil perfusion
Air-dried
Medium water
Water-saturated
Approx 50 days
Approx 30 days
No degradation
in 50 days
No degradation
in 50 days
Approx 22 days
1 month
205 days
Approx 72 days
21 days
>2 months
2 months
1 month
Kuwatsuka and
Igarashi, 1975
Kuwatsuka and
Igarashi, 1975
Young and
Carroll, 1951
Ide et al., 1972
Arsenault, 1976
Alexander and
Aleem, 1961
Watanabe, 1973
Loustalot and
Ferrer, 1950
-P-
OJ
-------
TABLE D.7.7.
433
DETERMINATION OF PENTACHLOROPHENOL IN SOIL SURROUNDING
PENTACHLOROPHENOL-TREATED UTILITY POLES
Location
Jackson, Tennessee
Savannah, Georgia
Spartanburg, South
Carolina
Gresham, Oregon
Soil type and condition
Well-drained clay
Well-drained clay
Well-drained clay
Sandy, well-drained, grass
and weeds next to pole
Sandy, well-drained, grass
and weeds next to pole
Sandy, well-drained, black
coating on soil within
6 in. , no vegetation
Clay loam
Clay loam
Clay loam
Clay loam
Clay loam
Loam, nearest plant 4 in.
from pole
Loam, no grass within 3 in.
of pole
Loam, no grass within 6 in.
of pole on east side and
2 in. on west side
Distance
from pole
(in.)
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
(cm)
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
Pentachlorophenol
content
(mg/kg soil)
1.4
0.13
0.04
0.32
0.05
0.04
120
3.1
0.81
620
0.08
0.04
1.9
0.05
0.03
1200
29
0.18
620
1.7
0.5
300
0.34
0.09
50
1.5
0.08
14
0.78
0.24
34
3.4
0.11
380
0.42
0.30
5200
40
0.4
9500
1.4
0.2
(continued)
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434
TABLE D.7.7 (continued)
Location Soil type and condition
Selma, Alabama Sandy loam
Sandy loam
Sandy loam
Montgomery, Alabama Sandy loam
Sandy loam
Sandy loam
Chico, California Sandy loam, vegetation
moderate around pole
Sandy loam, grass around
pole
Sandy loam, light vegeta-
tion around pole
Clay, heavy weeds around
pole
Clay, heavy vegetation
around pole
Paradise, California Clay, light grass to no
vegetation
Distance _. , .. , -
,. . Pentachlorophenol
from pole
content
(in.)
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
1
12
60
(cm)
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
2.54
30.5
152.4
(mg/kg soil)
5.2
0.54
0.34
16
0.74
0.44
12
1.8
0.60
7.4
0.94
1.0
4.8
2.2
0.48
32
0.88
0.30
0.72
0.22
0.16
1.3
0.14
0.22
0.19
0.16
0.18
0.22
0.07
0.09
0.42
0.22
0.26
0.70
0.20
0.20
Source: Adapted from Arsenault, 1976, Tables 6-11, pp. 16-19. Reprinted by permis-
sion of the publisher.
-------
435
the soil had an average content of 3.4 mg/kg, with a high value of 40
mg/kg. At 5 ft from the poles, pentachlorophenol concentrations averaged
0.26 mg/kg, which closely approximated the values obtained in unexposed
samples (0.2 to 0.4 mg/kg). This study indicates that leaching from
preservative-treated wood does not result in widespread contamination of
the surrounding soil. Biodegradation in the soil may account for the
gradually decreasing amounts of pentachlorophenol with greater distance
(Arsenault, 1976); also, some biodegradation may occur in the treated
wood.
Pentachlorophenol depletion in treated wood was also studied by
Leutritz (1965). The pentachlorophenol content of treated pine strips
exposed to sterile and nonsterile soils decreased by 22% to 27% over a
50-day incubation period. Because no differences were found between the
sterile and nonsterile environments, the author concluded that leaching
rather than biodegradation was responsible for pentachlorophenol depletion.
Other investigators have found that biodegradation of pentachloro-
phenol does occur in treated wood. Unligil (1968) demonstrated that a
common wood-inhabiting fungus {Tr>'lo'fioderrr.o. viride) and a wood-decaying
fungus (Con-iophora puteana) could metabolize pentachlorophenol; 62% of
the pentachlorophenol from samples containing 5.8 kg/m3 was dissipated in
52 days. Duncan and Deverall (1964) also demonstrated pentachlorophenol
degradation by common wood-inhabiting fungi. The ability of three species
of Trichoderma to degrade pentachlorophenol was demonstrated by Cserjesi
(1967). One species, Tri,choderma virgatum, degraded pentachlorophenol
by forming pentachloroanisole (Cserjesi and Johnson, 1972). Methylation
of pentachlorophenol by fungi was also reported by Curtis et al. (1974).
Three species found commonly in poultry litter — Scopulaxn.opsis bi?ewioc.y.~L-'is
Asperg-illus sydoui, and Penisill-iuT: crustosvj'i — catalyzed the methylation
reaction. Pentachloroanisole was not the sole metabolic product because
in one test system only 10% to 20% of the original pentachlorophenol was
present as pentachloroanisole, despite the fact that no pentachlorophenol
was detected following degradation (Cserjesi and Johnson, 1972). Penta-
chloroanisole may be the first step in the biodegradation of pentachloro-
phenol, or another pathway which does not include pentachloroanisole as
a product may exist.
In summary, pentachlorophenol is moderately stable in preservative-
treated wood and is slowly dissipated as a result of biodegradation and
leaching. The environmental hazard is probably minimal. Soil contamina-
tion is probably confined to very localized areas surrounding the treated
wood, and the pentachlorophenol which reaches the soil is degraded rapidly
enough to prevent any hazard to plants or animals.
D.7.3.5 Microbial Decomposition in Soils and Water
Pentachlorophenol is considered to be a refractory compound of the
chlorophenol family. Bacteria capable of degrading pentachlorophenol were
not isolated until Chu and Kirsch (1972) used continuous-flow enrichment
to isolate a bacterial culture (designated KC-3) capable of metabolizing
-------
436
pentachlorophenol as a sole source of organic carbon and energy. The
morphological and physiological characteristics of KC-3 suggested a rela-
tionship to the saprophytic coryneform bacteria. Chu and Kirsch (1973)
established that pentachlorophenol metabolism by KC-3 was highly respon-
sive to enzyme induction with pentachlorophenol as the inducer. Partial
induction of the pentachlorophenol-degrading system occurred when 2,4,6-
trichlorophenol was used as an inducer. KC-3 can degrade pentachloro-
phenol (200 mg/liter) in a complex organic medium, indicating that
pentachlorophenol metabolism is not precluded by the presence of other
nutrient substances (Hayes and Kirsch, 1973). Degradation products of
pentachlorophenol metabolism by KC-3 were not characterized.
A microbial population capable of rapid pentachlorophenol degrada-
tion was found in a soil sample from the grounds of a wood-products
manufacturer in Terre Haute, Indiana (Kirsch and Etzel, 1973). This
population was grown in media to which increasing amounts of pentachloro-
phenol were added for three months. When the microbes were fully accli-
mated (25 days), they were dosed with 100 mg/liter pentachlorophenol;
68% was degraded in 24 hr. The culture was most effective when penta-
chlorophenol was the sole source of carbon. When cells were grown in
nutrient broth containing pentachlorophenol (i.e., pentachlorophenol was
not the sole carbon source), oxidation was retarded by a factor of 2.
Thus, optimum conditions for growth of the organism are not necessarily
optimum for degradation of pentachlorophenol. Over a 60-day acclimation
period, the oxidation capacity of the culture increased initially and
then rapidly declined (Table D.7.8). The reason for this decline is not
known. The authors stated, "The data might be interpreted to mean that
the PCP-oxidizing organisms, although slower growing than other organisms
in the culture, gradually become a significant fraction of the population
as the result of some selective culture advantage that may have been
related to the gradually increasing concentration of exogenous PGP. The
reason for the sharp decrease in PCP-oxidizing capacity is not known."
Microbial degradation of pentachlorophenol was also identified by
Kuwatsuka and Igarashi (1975) in a bacterial culture derived from a paddy
soil. The degradation products were 2,3,4,5-, 2,3,4,6-, and 2,3,5,6,-
tetrachlorophenol; 2,3,4-, 2,4,5-, 2,3,5-, 2,3,6-, and 2,4,6-trichloro-
phenol; and pentachlorophenol methyl ether. Principal products were
pentachlorophenol methyl ether, 2,3,4,5-tetrachlorophenol, and 2,3,6- and
2,4,6-trichlorophenol. Ide et al. (1972) found many of the same degra-
dation products in paddy soils. The specific products identified were
2,3,4,5-, 2,3,5,6-, and 2,3,4,6-tetrachlorophenol; 2,4,5- and 2,3,5-
trichlorophenol; 3,4- and 3,5-dichlorophenol; and 3-monochlorophenol.
Pentachlorophenol methyl ether was not detected.
Watanabe (1973) reported pentachlorophenol degradation in soil
samples perfused with 40 mg/liter pentachlorophenol, but no degradation
products were characterized. Bacterial isolates were derived from a soil
perfusion enrichment culture. After two to three weeks incubation at
30°C, degradation and complete dechlorination of pentachlorophenol were
caused by Pseudomonas sp. or a bacterium from a closely related genera.
Degradation was most efficient in a medium containing pentachlorophenol
-------
437
TABLE D.7.8. OXIDATION OF
PENTACHLOROPHENOL BY A HETEROGENEOUS
ACCLIMATING BIOMASSa
Sampling
time
(days)
1
5
7
12
20
25
32
39
42
47
53
57
C02 formed
(dpm/day)
4,400
5,100
9,800
20,000
17,000
31,000
31,000
29,000
27,000
17,000
4,000
50
Oxidative
capacity^3
(%)
10
11
22
44
38
68
68
65
61
38
9
1
During this acclimation cycle a 4-
liter completely mixed, aerated reactor
received 40 mg/day pentachlorophenol and
500 mg/day nutrient broth.
^Percent radioactive pentachlorophenol
carbon converted to C02 in 24 hr.
Source: Adapted from Kirsch and Etzel,
1973, Table IV, p. 362. Reprinted by per-
mission of the publisher.
and inorganic salts. When the organism was cultured on glucose bouillon
agar containing pentachlorophenol, growth was slower and pentachlorophenol
was not degraded. Thus, pentachlorophenol is an adequate, but not a pre-
ferred, substrate for this bacterium.
Cserjesi (1972) used gas chromatography to tentatively identify
tetrochlorodihydroxyphenols and their monomethyl ethers as metabolic
products of pentachlorophenol by Aspergillus sp.; no dimethyl ethers
were detected. A soil bacterium isolated by Suzuki and Nose (1971, as
cited by Cserjesi, 1972) degraded pentachlorophenol. The major metabo-
lite was pentachloroanisole; tetrachlorohydroquinone dimethyl ether was
identified as a minor metabolite.
Investigations by Arsenault (1976) demonstrated pentachlorophenol
degradation by microorganisms in soil. Pentachlorophenol-containing
sludges from commercial wood-treating operations were composted with a
"permeable" soil. Quantitative degradation of pentachlorophenol occurred
-------
438
in 205 days if the pentachlorophenol concentration did not exceed 200
Vig/g. In another experiment, process water from a wood-treating plant
containing 35 rag/liter pentachlorophenol was percolated through soil col-
umns in the laboratory. Over a 2.5-year period, effluent water from 1-m
columns consistently contained less than 1 mg/liter pentachlorophenol.
Also, pentachlorophenol-containing sludges were composted with soil at
concentrations of 100, 200, and 300 mg/liter, and distilled water was
added weekly to simulate rainfall. After 205 days, the soil and leach-
ates were analyzed for pentachlorophenol and only negligible amounts were
found (Table D.7.9). The soil was contained in 20-cm glass vessels to
approximate topsoil cover in the field.
TABLE D.7.9. LEACHING OF PENTACHLOROPHENOL FROM
"PENTA SLUDGES" IN SOIL IN 205 DAYS
Leachate
volume
(ml)
3597
3459
3712
Pentachlorophenol in leachate
(mg/liter)
0.019
0.067
0.108
(mg)
0.070
0.23
0.40
(% of original
pentachlorophenol)
0.0048
0.0061
0.0070
Source: Adapted from Arsenault, 1976, Table 13,
p. 20. Reprinted by permission of the publisher.
Watanabe (1977) demonstrated in field plot studies that within six
weeks after initial application of pentachlorophenol, pentachlorophenol-
decomposing microorganisms increased by three orders of magnitude. Some
specificity was noted; soils receiving pentachlorophenol were not enriched
with tetrachlorophenol-decomposing microorganisms.
In summary, bacteria and fungi capable of degrading pentachloro-
phenol exist in the environment, but these microorganisms may not be
widespread. In most cases of rapid pentachlorophenol degradation by
microorganisms, the source of the initial microbial inoculum was an area
where pentachlorophenol had been used for a considerable time. For
example, microorganisms capable of degrading pentachlorophenol were
derived from soil cultures from wood preserving plants where the soil
was frequently saturated with pentachlorophenol. Other inocula were
derived from paddy fields where pentachlorophenol was widely used as a
herbicide and from sewage treatment facilities exposed to high inputs
of pentachlorophenol. In other cases, enrichment cultures were exposed
-------
439
to gradually increasing amounts of pentachlorophenol. Bacteria may or
may not possess qualities which allow them to compete effectively in a
mixed population. Watanabe (1973) and Kirsch and Etzel (1973) reported
that pentachlorophenol-degrading bacteria may not be optimally efficient
in the presence of alternative substrates such as nutrient broth. How-
ever, the bacteria isolated by Chu and Kirsch (1972), KC-3, degraded
pentachlorophenol in the presence of other nutrients. Thus, some bac-
teria may have the capability of degrading pentachlorophenol in the
presence of other organic nutritional sources. Metabolic pathways for
pentachlorophenol degradation and the environmental fate of pentachloro-
phenol metabolites are areas for further investigation.
D.7.3.6 Photodecomposition
The photochemistry of pentachlorophenol and other chlorinated pheno-
lic herbicides has been widely investigated. Model studies have shown
that aqueous solutions of pentachlorophenol or its salts are subject to
photodecomposition, and this observation has been reinforced by practical
experience in the field.
D.7.3.6.1 Mechanism — Photochemical reactions of halogenated aro-
matic compounds appear to follow free-radical pathways (Plimmer, 1970).
Because of the free-radical character of the reaction, the structure of
the products depend on the properties of the solvent. Water is the sol-
vent involved in the environmental photochemical reactions; therefore,
studies of photochemical degradation in aqueous solutions are particu-
larly pertinent. Results of photochemical reactions in nonaqueous sol-
vents should be carefully examined for applicability to environmental
conditions.
The absorbance spectrum of phenols undergoes a characteristic
bathochromatic shift with change from the protonated form to the anion.
Because the wavelength of light absorbed is affected, it is reasonable
to assume that there are changes in photochemical behavior as well.
According to Plimmer (1970), the nature of the reaction products depends
on the wavelength of light absorbed. Another factor which influences
the spectrum of a molecule is the surfaces with which it is associated
in the environment, or more specifically, bonding interactions with the
surface. Interactions which affect the reaction products include simple
adsorption, coulombic forces, van der Waals forces, and charge transfer.
In short, the chemical environment of the molecule profoundly influences
its photochemical behavior. Unfortunately, there have been relatively
few studies of pesticide photochemistry on environmental surfaces
(Plimmer, 1970). Adsorption on silica does cause a shift in the ultra-
violet spectra, which provides evidence for hydrogen bonding of the
phenol. Aqueous solutions of sodium pentachlorophenate decomposed when
exposed to sunlight, as evidenced by a color change from clear to purple
after about ten days (Munakata and Kuwahara, 1969).
Hamadmad (1967) characterized some of the breakdown products of penta-
chlorophenol in various solutions. Ultraviolet irradiation of pentachloro-
phenol in hexane or MeOH gave 2,3,5,6-tetrachlorophenol, presumably by
-------
440
reductive dechlorination. However, an aqueous suspension of pentachloro-
phenol produced little tetrachlorophenol when irradiated; polymeric sub-
stances were the major photolysis products. Crosby and Hamadmad (1971)
concluded that 2,3,5,6-tetrachlorophenol was the major breakdown product
of pentachlorophenol photolysis, but they used only organic solvents and
no aqueous solutions. Munakata and Kuwahara (1969) studied the photo-
chemical reaction products obtained when an aqueous solution of 20 g/liter
sodium pentachlorophenate was irradiated. After ten days of sunshine, 50%
of the sodium pentachlorophenate was lost. The chemical structures of the
degradation products are shown in Figure D.7.1.
D.7.3.6.2 Effect of Photodecomposition — Hiatt, Haskins, and Olivier
(1960) recognized that photochemical degradation may be a factor which
ORNL—DWG 78-10538
Cl Cl
Cl
0 Cl
2.5-DICHLORO-3-HYDROXY-6-
PENTACHLOROPHENOXY-1,4-
BENZOQUINONE
(RED)
2,4,5,6—TETRACHLORORESORCINOL
(COLORLESS)
Cl
2,5-DICHLORO-3-HYDROXY-6-(3-
HYDROXY- 2,4,5,6-TETRACHLORO-
PHENOXY)- 1 ,4-BENZOQUINONE
(ORANGE RED)
Cl Cl
Cl
3-(2-HYDROXY-3,4,5,6-TETRA-
CHLOROPHENOXY)-4,5,6-
TRICHLORO-1, 2-BENZOQUINONE
(YELLOW)
Cl
Cl
3,5-DICHLORO-4-HYDROXY-2,3,5,6-TETRACHLORO-
PHENOXY-6,2-HYDROXY-3,4,5,6-TETRACHLORO-
PHENOXY-1,2-BENZOQUINONE
(YELLOW)
CHLORANILIC ACID
Figure D.7.1. Photochemical degradation products obtained from
irradiation of an aqueous solution of sodium pentachlorophenate. Source;
Adapted from Munakata and Kuwahara, 1969, Figure III, p. 17. Reprinted
by permission of the publisher.
-------
441
reduces the efficacy of pentachlorophenol on its target organism. They
reported field observation of unexpectedly poor control of the snail vec-
tors of schistosomiasis in South African streams. These streams were all
small, shallow, and rapidly flowing and were exposed to full sunlight dur-
ing the day. The water was exceptionally clear. They speculated that
photochemical destruction of sodium pentachlorophenate was the cause of
the poor control. Results of a laboratory study by Hiatt, Raskins, and
Olivier (1960) confirmed this hypothesis (Table D.7.10). The lethal
effects of irradiated and control solutions were not significantly dif-
ferent. Thus, the decrease in sodium pentachlorophenate concentration
in the irradiated samples, as measured by chemical methods, was accom-
panied by a decline in molluscicidal effects, which indicates that the
decomposition products are nontoxic to snails.
TABLE D.7.10. SNAIL EGGS KILLED WITHIN 24 hr BY IRRADIATED AND
UNTREATED SOLUTIONS WHEN EACH SOLUTION WAS DILUTED TO THE
SODIUM PENTACHLOROPHENATE CONCENTRATION
Sodium
pentachlorophenate
concentrat ion
(mg/liter)
0.12
0.20
0.25
0.34
0.5
1.0
Number
of eggs
68
66
182
90
160
116
Eggs
killed
0
73
88
92
89
98
Number
of eggs
75
80
130
74
107
128
OUJ-LK — LUll
Eggs
killed
5
76
82
100
100
100
Source: Adapted from Hiatt, Haskins, and Olivier, 1960, Table
2, p. 529. Reprinted by permission of the publisher.
The photochemical breakdown products discussed by Munakata and
Kuwahara (1969) (Figure D.7.1) were tested for toxicity. The degradation
products showed stronger fungicidal effects but weaker phototoxicity and
fish toxicity than pentachlorophenol. Fungicidal effects were tested on
leaf blight (Zanthomonas oryzae), rice blast (Piricularia oryzae), pear
black spot (Alternaria kikuchiand), and grape ripe rot (GlomeTella cingu-
latd). Phytotoxic effects were tested on seeds of rice and rape. Fish
toxicity was examined using Japanese killifishes (Oryzias latipes).
-------
442
D.7.4 WASTE MANAGEMENT
Primary waste treatment processes are expected to be equally effi-
cient with wastewater containing high amounts of pentachlorophenol (e.g.,
from wood preserving plants) or wastewaters containing low concentrations
of pentachlorophenol (e.g., municipal sewage). Biological treatment of
wastewater, on the other hand, requires the presence of acclimated popu-
lations of bacteria capable of degrading pentachlorophenol, which is more
likely when a constant high level of pentachlorophenol is present (e.g.,
treatment of wastewater from wood preserving operations).
D.7.4.1 Primary Treatment
Primary treatment of wastewater involves the removal of particulate
substances and emulsified oils. The effect of this type of treatment on
the pentachlorophenol content of wastewater is probably minimal. Penta-
chlorophenol dissolved in oil is removed by this process, but pentachloro-
phenol dissolved in water is not. Because pentachlorophenol is highly
soluble in organic solvents, its removal from wastewater from wood preserv-
ing operations may be substantial. Sodium pentachlorophenate, however,
is highly soluble in water, and its removal by flocculation treatments is
unlikely. Thompson and Dust (1971) treated wastewater samples containing
pentachlorophenol with various amounts of lime and monitored the penta-
chlorophenol concentration. The wastewater contained substantial amounts
of oils. The residual pentachlorophenol concentrations were reduced from
150 to 17 mg/liter with application of 2 g/liter of lime. The solubility
of pentachlorophenol in water is approximately 17 mg/liter; thus, penta-
chlorophenol removal was assumed to be a result of flocculation "of penta-
chlorophenol entrained in the oil. Wastewaters which do not contain oil
probably do not show substantial reduction of pentachlorophenol levels
unless the pentachlorophenol (or sodium pentachlorophenate) is adsorbed
to sediment particles.
D.7.4.2 Secondary Treatment
Secondary treatment involves the removal of organic matter from
wastewater by biological processes. Biological oxidation is widely used
in processing domestic and industrial wastes. This method depends on the
ability of microbial populations to degrade organic waste with the forma-
tion of nontoxic metabolites such as carbon dioxide and water. A number
of different methods are used — trickling filtration, activated sludge,
oxidation lagoons, and soil irrigation, as well as many variations of
these basic methods. The effectiveness of trickling filtration and soil
irrigation as biological treatment methods for pentachlorophenol has not
been reported.
Evidence exists that pentachlorophenol-containing effluents can be
degraded in an aeration lagoon (Sidwell, 1971). Pentachlorophenol was
added to aeration lagoon influent, and the aerated solution was continu-
ously analyzed for pentachlorophenol. In separate experiments, the penta-
chlorophenol concentration decreased from 39.5 to 0.5 mg/liter in three
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443
days and from 81 to 0.6 mg/liter in 30 hr. Thus, based on one laboratory
study, the aeration lagoon is a reasonably efficient process for the sec-
ondary treatment of wastewater containing pentachlorophenol.
The effectiveness of activated sludge treatment on the pentachloro-
phenol content of wastewater is somewhat controversial. The ability of
an activated sludge preparation to degrade various chlorophenols was stud-
ied by Ingols and Stevenson (1963). The sludge was acclimated to the
presence of chlorophenols over a period of several months. Pentachloro-
phenol was the only chlorophenol tested which resisted degradation by
the activated sludge population. In contrast, other investigators have
demonstrated the ability of activated sludge preparations to degrade
pentachlorophenol. Dust and Thompson (1973) studied the biodegradability
of pentachlorophenol using bench-scale activated sludge units; removal
efficiencies in excess of 90% were obtained. Waste from a wood preserv-
ing plant containing 23 mg/liter pentachlorophenol was treated success-
fully in the laboratory to produce an effluent containing 0.4 mg/liter
pentachlorophenol (Kirsch and Etzel, 1973). Arsenault (1976) also found
that activated sludge preparations obtained from wood preserving plants
were capable of pentachlorophenol degradation. Thus, under specific
laboratory conditions, activated sludge populations apparently are capable
of degrading pentachlorophenol. The efficiency of this process must be
assessed on an individual basis for each sewage treatment plant.
Of more serious concern is the effect of pentachlorophenol on acti-
vated sludge treatment when the compound is not a regular component of
the influent wastewater. This situation could arise in municipal treat-
ment plants subject to shock-loading conditions from nearby pentachloro-
phenol manufacturers or users (Section D.3.1.2).
D.7.4.3 Chemical Oxidation
Removal of phenols from municipal water supplies by chemical oxida-
tion is routinely practiced because of the objectionable taste and odor
even when they are present in relatively low concentrations. Chemical
treatments involving the oxidation of phenols with chlorine, chlorine
dioxide, ozone, and Fenton's reagent (H202 plus a ferrous iron salt) have
been reported (Eisenhauer, 1964). Fenton's reagent does not attack penta-
chlorophenol. Vigorous oxidation of pentachlorophenol with nitric acid
produces a mixture of tetrachloro-0-quinone and tetrachloro-p-quinone — a
reaction exploited as a colorimetric analysis. It is unlikely that the
less drastic oxidations used in waste treatment will go beyond the quinone
stage and cause ring cleavage. If they do give oxidation products similar
to those of the nitric acid reaction, they may reduce the toxicity of
pentachlorophenol. Oxidation by ozone is a relatively new technique, and
its effectiveness in degrading pentachlorophenol in wastewater has not
been fully assessed.
Treatment of wastewater with chlorine or chlorine dioxide, a commonly
used method, may be useful in treating wastewater from wood treatment
plants. According to Thompson (1973), chlorination of pentachlorophenol
results in the formation of chloranil, a compound which is much less toxic
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444
and more readily biodegradable than the parent chemical pentachlorophenol.
However, chlorination of municipal wastes may cause more problems than it
solves. Although Ingols and Ridenour (1948) reported that the oxidation
of phenolic compounds by chlorine does not result in the formation of pen-
tachlorophenol, more recent work (Arsenault, 1976) indicates that penta-
chlorophenol can be formed in municipal sewage treated with chlorine.
Thus, under appropriate conditions, pentachlorophenol may be synthesized
as a result of municipal chlorination of wastewater. This objection also
applies to the chlorination of municipal drinking water supplies. Another
more subtle hazard exists when chlorination is used for the treatment of
wastewater or drinking water. Ingols, Gaffney, and Stevenson (1966) found
that although there is a dramatic reduction in biochemical oxygen demand
following chlorination, this reduction does not indicate total oxidation
of organic molecules in the water. Chlorination may result in the syn-
thesis of substituted chlorophenols or chlorophenolic compounds which
are no longer susceptible to detection by measuring biochemical oxygen
demand. Thus, chlorination may merely mask the presence of potentially
hazardous organic molecules in drinking water.
D.7.4.4 Activated Carbon Adsorption
Activated carbon adsorption is an effective means of treating waste-
water. Activated carbon has a strong affinity for nonpolar compounds such
as phenols and would be expected to adsorb pentachlorophenol. The method
is expensive and is not widely used, particularly in the treatment of
wastewater from wood treatment plants. Data on the efficiency of penta-
chlorophenol adsorption by activated carbon was not found.
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445
SECTION D.7
REFERENCES
1. Alexander, M., and M.I.H. Aleem. 1961. Effect of Chemical Structure
on Microbial Decomposition of Aromatic Herbicides. J. Agric. Food
Chem. 9(1):44-47.
2. Anonymous. 1970. Pentachlorophenol Poisoning in the Home. Calif.
Health 27(12):13.
3. Anonymous. 1972. Chemical Profile: Pentachlorophenol. Chem. Mark.
Rep. 201:9.
4. Arsenault, R. D. 1970. Pentachlorophenol Concentration in Utility
Poles and Its Effectiveness in Preventing Decay after a Quarter
Century in Wisconsin. Proc. Am. Wood Preserv. Assoc. 66:97-109.
5. Arsenault, R. D. 1976. Pentachlorophenol and Contained Chlorinated
Dibenzodioxins in the Environment: A Study of Environmental Fate,
Stability, and Significance When Used in Wood Preservation. Proc.
Am. Wood Preserv. Assoc. pp. 1-25.
6. Bevenue, A., and H. Beckman. 1967. Pentachlorophenol: A Discussion
of Its Properties and Its Occurrence as a Residue in Human and Animal
Tissues. Residue Rev. 19:83-134.
7. Bevenue, A., J. W. Hylin, Y. Kawano, and T. W. Kelley. 1972.
Organochlorine Pesticide Residues in Water, Sediment, Algae, and
Fish, Hawaii - 1970-71. Pestic. Monit. J. 6(l):56-64.
8. Bevenue, A., J. N. Ogata, and J. W. Hylin. 1972. Organochlorine
Pesticides in Rainwater, Oahu, Hawaii, 1971-1972. Bull. Environ.
Contain. Toxicol. 8(4) : 238-241.
9. Bevenue, A., J. Wilson, L. J. Casarett, and H. W. Klemmer. 1967.
A Survey of Pentachlorophenol Content in Human Urine. Bull. Environ.
Contain. Toxicol. 2(6) :319-332.
10. Buhler, D. R., M. E. Rasmusson, and H. S. Nakaue. 1973. Occurrence
of Hexachlorophene and Pentachlorophenol in Sewage and Water. Environ.
Sci. Technol. 7(10):929-934.
11. Casarett, L. J., A. Bevenue, W. L. Yauger, Jr., and S. A; Whalen.
1969. Observations on Pentachlorophenol in Human Blood and Urine.
Am. Ind. Hyg. Assoc. J. 30(4):360-366.
12. Chu, J. P., and E. J. Kirsch. 1972. Metabolism of Pentachlorophenol
by an Axenic Bacterial Culture. Appl. Microbiol. 23(5):1033-1035.
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446
13. Chu, J., and E. J. Kirsch. 1973. Utilization of Halophenols by a
Pentachlorophenol Metabolizing Bacterium. Dev. Ind. Microbiol.
14:264-273.
14. Crosby, D. G., and N. Hamadmad. 1971. The Photoreduction of Penta-
chlorobenzenes. J. Agric. Food Chem. 19(6):1171-1174.
15. Cserjesi, A. J. 1967- The Adaptation of Fungi to Pentachlorophenol
and Its Biodegradation. Can. J. Microbiol. 13(9):1243-1249.
16. Cserjesi, A. J. 1972. Detoxification of Chlorinated Phenols. Int.
Biodeterior. Bull. 8(4):135-138.
17. Cserjesi, A. J., and E. L. Johnson. 1972. Methylation of Pentachlo-
rophenol by Trichoderma virgatum. Can. J. Microbiol. 18(l):45-49.
18. Curtis, R. F., C. Dennis, J. M. Gee, M. G. Gee, N. M. Griffiths,
D. G. Land, J. L. Peel, and D. Robinson. 1974. Chloroanisoles as
a Cause of Musty Taint in Chickens and Their Microbiological Forma-
tion from Chlorophenols in Broiler House Litters. J. Sci. Food Agric.
25(7):811-828.
19. Duncan, C. G., and F. J. Deverall. 1964. Degradation of Wood Pre-
servatives by Fungi. Appl. Microbiol. 12(l):57-62.
20. Dust, J. V., and W. S. Thompson. 1973. Pollution Control in the
Wood-Preserving Industry: Part IV. Biological Methods of Treating
Wastewater. For. Prod. J. 23(9):59-66.
21. Eisenhauer, H. R. 1964. Oxidation of Phenolic Wastes: Part I.
Oxidation with Hydrogen Peroxide and a Ferrous Salt Reagent. J.
Water Pollut. Control Fed. 36(9):1116-1128.
22. Environmental Health Advisory Committee. 1978. Report of the Ad Hoc
Study Group on Pentachlorophenol Contaminants (Draft Report). U.S.
Environmental Protection Agency, Washington, D.C. pp. V-3-28 to
V-3-32.
23. Ferguson, E. R. 1959. Wood Treated with Penta Can Damage Pine
Nursery Seedlings. Tree Plant. Notes 38:21-22.
24. Fountaine, J. E., P. B. Joshipura, and P. N. Keliher. 1976. Some
Observations Regarding Pentachlorophenol Levels in Haverford Town-
ship, Pennsylvania. Water Res. 10:185-188.
25. Gjovik, L. R., B. A. Bendtsen, and H. G. Roth. 1972. Condition of
Preservative-Treated Cooling Tower Slats after 10-Year Service. For.
Prod. J. 22(4):35-40.
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26. Goto, M. 1971. Organochlorine Compounds in the Environment in Japan.
In: Pesticide Terminal Residues, International Symposium on Pesticide
Terminal Residues, Tel Aviv, A. S. Tahori, ed. Butterworth, New York.
pp. 105-110.
27. Hamadmad, N. 1967. Photolysis of Pentachloronitrobenzene, 2,3,4,6-
Tetrachloronitrobenzene and Pentachlorophenol. Ph.D. Thesis. Uni-
versity of California, Davis. 87 pp.
28. Hayes, T. D., and E. J. Kirsch. 1973. Influence of Growth Tempera-
ture on the Bacterial Degradation of Sodium Pentachlorophenate
(abstract). Abstr. Annu. Meet. Am. Soc. Microbiol. 73:183.
29. Hiatt, C. W., W. T. Raskins, and L. Olivier. 1960. The Action of
Sunlight on Sodium Pentachlorophenate. Am. J. Trop. Med. Hyg.
9:527-531.
30. Higginbotham, G. R., J. Ress, and A. Rocke. 1970. Extraction and
GLC Detection of Pentachlorophenol and 2,3,4,6-Tetrachlorophenol in
Fats, Oils, and Fatty Acids. J. Assoc. Off. Anal. Chem. 53(4):673-676.
31. Hilton, H. W., Q. H. Yuen, and N. S. Nomura. 1970. Distribution of
Residues from Atrazine, Ametryne, and Pentachlorophenol in Sugarcane.
J. Agric. Food Chem. 18(2):217-220.
32. Ide, A., Y. Niki, F. Sakamoto, I. Watanabe, and H. Watanabe. 1972.
Decomposition of Pentachlorophenol in Paddy Soil. Agric. Biol. Chem.
36(11):1937-1944.
33. Ifeadi, C. N. 1975. Screening Study to Develop Background Informa-
tion and Determine the Significance of Air Contaminant Emissions from
Pesticide Plants. EPA 540/9-75-026a, U.S. Environmental Protection
Agency, Washington, D.C. 73 pp.
34. Ingols, R. S., P. E. Gaffney, and P. C. Stevenson. 1966. Biological
Activity of Halophenols. J. Water Pollut. Control Fed. 38(4):629-635.
35. Ingols, R. S., and G. M. Ridenour. 1948. The Elimination of Phenolic
Tastes by Chloro-oxidation: A Suggested Explanation of the Mechanism
of Reactions in the Chlorination Process. Water & Sewage Works
95:187-190.
36. Ingols, R. S., and P. C. Stevenson. 1963. Biodegradation of Chlori-
nated Organic Compounds. Georgia Institute of Technology, Atlanta.
29 pp.
37. Kirsch, E. J., and J. E. Etzel. 1973. Microbial Decomposition of
Pentachlorophenol. J. Water Pollut. Control Fed. 45(2):359-364.
38. Kuwatsuka, S., and M. Igarashi. 1975. Degradation of PCP in Soils:
II. The Relationship between the Degradation of PCP and the Proper-
ties of Soils, and the Identification of the Degradation Products of
PCP. Soil Sci. Plant Nutr. 21(4):405-414.
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448
39. Leutritz, J. 1965. Biodegradability of Pentachlorophenol. For.
Prod. J. 15(7):269-272.
40. Leutritz, J. 1971. Stabilization of Pentachlorophenol as Indicated
by Extraction from Wood Samples with Different Solvents. Proc. Am.
Wood Preserv. Assoc. 67:198-203.
41. Loustalot, A. J., and R. Ferrer. 1950. The Effect of Some Environ-
mental Factors on the Persistence of Sodium Pentachlorphenate in the
Sil. Proc. Am. Soc. Hortic. Sci. 56:294-298.
42. Lu, P. Y., and R. L. Metcalf. 1975. Environmental Fate and Bio-
degradability of Benzene Derivatives as Studied in a Model Aquatic
Ecosystem. Environ. Health Perspect. 10:269-284.
43. Munakata, K., and M. Kuwahara. 1969. Photochemical Degradation
Products of Pentachlorophenol. Residue Rev. 25:13-23.
44. Nitta, T. 1972. Marine Pollution in Japan. In: Marine Pollution
and Sea Life. Fishing News Ltd., London, pp. 77-81.
45. Pierce, R. H., C. R. Brent, H. P. Williams, and S. G. Reeves. 1977.
Pentachlorophenol Distribution in a Fresh Water Ecosystem. Bull.
Environ. Contam. Toxicol. 18:251-258.
46. Plakhova, L. G. 1966. Allowable Concentration of Sodium Pentachlo-
rophenolate in the Air of Working Areas. Chem. Abstr. 69:7497.
47. Plimmer, J. R. 1970. The Photochemistry of Halogenated Herbicides.
Residue Rev. 33:47-74.
48. Shim. J. C., and L. S. Self. 1973. Toxicity of Agricultural Chem-
icals to Larvivorous Fish in Korean Rice Fields. Trop. Med. (Nettai
Igaku) 15(3):123-130.
49. Sidwell, A. E. 1971. Biological Treatment of Chlorophenolic Wastes:
The Demonstration of a Facility for the Biological Treatment of a
Complex Chlorophenolic Waste. Water Pollution Control Research Ser-
ies. U.S. Environmental Protection Agency, Washington, D.C. 177 pp.
50. Strufe, R. 1968. Problems and Results of Residue Studies after
Application of Molluscicides. Residue Rev. 24:79-168.
51. Thompson, W. S. 1973. Pollution Control. In: Wood Deterioration
and Its Prevention by Preservative Treatments, Vol. II, Preservatives
and Preservative Systems, D. D. Nicholas, ed. Syracuse University
Press, Syracuse, N.Y. pp. 345-395.
52. Thompson, W. S., and J. V. Dust. 1971. Pollution Control in the
Wood Preserving Industry: Part I. Nature and Scope of the Problem.
For. Prod. J. 21(9):70-75.
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53. Thompson, W. S. , G. D. McGinnis, and L. L. Ingram, Jr. 1978. The
Volatilization of Pentachlorophenol from Treated Wood. Mississippi
State University, Mississippi State, Miss. 8 pp.
54. Unligil, H. H. 1968. Depletion of Pentachlorophenol by Fungi. For.
Prod. J. 18(2):45~50.
55. Vermeer, K., R. W. Risebrough, A. L. Spaans, and L. M. Reynolds.
1974. Pesticide Effects on Fishes and Birds in Rice Fields of
Surinam, South America. Environ. Pollut. 7(3):217-236.
56. Vind, H. P., J. S. Muraoka, and C. W. Mathews. 1973. Biodeteriora-
tion of Navy Insecticides in the Ocean. U.S. Office of Naval Research,
Arlington, Va. 14 pp.
57. Walters, C. S., and R. D. Arsenault. 1971. The Concentration and
Distribution of Pentachlorophenol in Pressure-Treated Pine Pole-Stubs
after Exposure. Proc. Am. Wood Preserv. Assoc. 67:149-169.
58. Watanabe, I. 1973. Isolation of Pentachlorophenol Decomposing Bac-
teria from Soil. Soil Sci. Plant Nutr. 19(2):109-116.
59. Watanabe, I. 1977. Pentachlorophenol-Decomposing and PGP-Tolerant
Bacteria in Field Soil Treated with PCP. Soil Biol. Biochem. 9:99-103.
60. Young, H. C., and J. C. Carroll. 1951. The Decomposition of Penta-
chlorophenol When Applied as a Residual Pre-emergence Herbicide. Agron.
J. 43:504-507.
61. Zitko, V., 0. Hutzinger, and P.M.K. Choi. 1974. Determination of
Pentachlorophenol and Chlorobiphenylols in Biological Samples. Bull.
Environ. Contain. Toxicol. 12(6) :649-653.
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D.8 ENVIRONMENTAL INTERACTIONS AND THEIR CONSEQUENCES
D.8.1 ENVIRONMENTAL CYCLING OF PENTACHLOROPHENOL
The sources, distribution, and fate of pentachlorophenol in soil,
water, and air are discussed in Section D.7. No comprehensive investi-
gations have been made on the movement of pentachlorophenol within or
among these three segments of the environment. For example, it has been
shown that pentachlorophenol volatilizes from aqueous solutions, but the
rate and extent of volatilization from particular locations have not been
studied. A possible environmental cycle for pentachlorophenol is pre-
sented in Figure A.8.1. Although the interactions shown have been veri-
fied (in most cases by laboratory studies), the extent of these processes
in the environment is speculative. Further investigations — perhaps uti-
lizing radiotracer techniques — are needed to clarify these interactions.
Pentachlorophenol contamination of the environment may arise from three
sources: (1) the manufacture and use of the compound as a wood preserva-
tive or pesticide, (2) degradation and resynthesis of other commonly used
compounds, and (3) municipal chlorination of water containing phenolic
compounds. The use of pentachlorophenol as a wood preservative is the
most significant source of environmental pollution; the other two sources
have not been investigated sufficiently. The data available, although
scanty, provide some basis for speculation. This assessment may err on
the side of caution since the hazards of low levels of pentachlorophenol
in the environment have not been evaluated.
The effects of acute doses of pentachlorophenol on animals and humans
are well documented. Acute intoxication can be easily avoided if appro-
priate safety measures are taken. Use of pentachlorophenol as a mollusci-
cide, a herbicide, or an algicide should be carefully examined in light
of the known toxic effects on aquatic and terrestrial wildlife. Sensitive
species of fish perish at concentrations as low as 30 yg/liter (Section
D.5.2.2.2.3).
The effects of chronic low levels of pentachlorophenol in humans and
animals are unclear. Low levels in the urine of nonoccupationally exposed
persons have been reported (Section D.6.2.2.4.2). Chronic exposure to
pentachlorophenol was correlated with increased total bilirubin and cre-
atine phosphokinase, gamma mobility, C-reactive protein, and liver enzyme
activity. These findings, however, have not been corroborated and their
clinical significance, if any, is unknown. In one investigation penta-
chlorophenol was detected in human adipose tissue (Section D.6.2.2.4.2).
Accumulation in fatty tissue must be considered a distinct possibility,
and the hazards associated with this accumulation warrant further
investigation.
D.8.2 HUMAN EXPOSURE
Human exposure to pentachlorophenol may occur through air, water,
and/or food. Exposure to pentachlorophenol in air has not been well
documented, although acute pentachlorophenol poisoning by the respiratory
450
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451
route is known (Section D.6.1.1.1). Casarett et al. (1969) suggested
that respiratory tract absorption could explain the almost ubiquitous
presence of pentachlorophenol in the urine of nonoccupationally exposed
persons. No reports assessed the relationship between airborne penta-
chlorophenol and concentrations of the compound in humans.
A similar lack of data prevents the adequate description of penta-
chlorophenol contamination of water. Pentachlorophenol levels in lake
and river waters have been reported in the range of 0.01 to 10 mg/liter,
but these values are based on a very few analyses and may not accurately
reflect pentachlorophenol concentrations in the aquatic environment.
Consequently, prevalent and ambient pentachlorophenol levels in water are
rough estimates. The amount of human uptake of pentachlorophenol from
water has not been determined.
More information is available on the levels of pentachlorophenol in
foodstuffs. Since 1964, the U.S. Food and Drug Administration has con-
ducted a program to monitor pesticide residues, including pentachloro-
phenol, in food. The sampling procedure involves gathering market baskets
from 30 stores in 27 cities across the United States. Each basket con-
sists of 82 to 117 food items and represents the dietary requirements of
a male in the 16- to 19-year-old age group for a two-week period. The
food items, chosen with the advice and assistance of the U.S. Department
of Agriculture, are selected for that particular group because of the
proportionally greater amount of food they consume. The contents of each
sample basket are divided into 12 classes and aliquots are analyzed.
Results are reported as either percentage of composite samples showing
detectable pentachlorophenol levels and/or as average individual daily
intake expressed as milligrams per person per day. From 1965 to 1969,
1% to 3.3% of the composite samples showed detectable levels of penta-
chlorophenol (Table D.6.36). Individuals consuming contaminated food
were exposed to a daily dietary intake of pentachlorophenol ranging from
0.001 to 0.006 mg per person. Daily intake of pentachlorophenol from
specific food categories is given in Table D.6.37. Pentachlorophenol
does not appear to be present predominantly in any single food class.
Johnson and Manske (1976) surveyed the pesticide residues in market
basket samples. They reported pentachlorophenol in 9 of 360 composites
at levels of 0.01 to 0.02 mg/kg.
No information is available on specific geographical areas where
contaminated food samples originated; therefore, it is impossible to
correlate intake by humans with the extent of pentachlorophenol use or
application. Although some portion of the U.S. population is exposed to
low levels of pentachlorophenol through food consumption, it is not known
whether the associated hazards are potential or actual.
D.8.3 BIOMAGNIFICATION IN FOOD CHAINS
The available data on environmental contamination by pentachlorophenol
preclude definitive conclusions regarding the effects of pentachlorophenol
in terrestrial ecosystems. Food chain biomagnification in terrestrial
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ecosystems has not been adequately studied and should be investigated.
Pentachlorophenol biomagnification in aquatic systems is well documented,
although the extent of the magnification and species variability have not
been fully elucidated. Consequently, the effects of these processes on
daily human intake of pentachlorophenol from food are not known. Investi-
gations are needed so that government officials and the public can be
fully appraised of the environmental impacts of pentachlorophenol and can
determine if additional cautionary measures should be taken.
D.8.3.1 Terrestrial Ecosystems
The sources of pentachlorophenol contamination in foodstuffs have
not been clearly described. Little information is available on distribu-
tion and transport in crops following pentachlorophenol application or
exposure. In laboratory studies, pentachlorophenol was taken up by the
root system of sugar cane grown in an aerated nutrient solution but was
not translocated to other parts of the plant. However, pentachlorophenol
or its metabolites may be translocated in cotton plants following spraying
(Section D.4.1). Pentachlorophenol is not commonly applied directly to
row crops intended for human consumption, but its ability to persist on
foliage for at least eight weeks implies a potential hazard from spraying
techniques. Pentachlorophenol application to pastureland has been reported
(Section D.5.1.1.1.3), but this use is probably minimal. Cattle seem to
avoid pentachlorophenol-treated grasses by preference of taste; however,
the possibility exists that pentachlorophenol may be concentrated in the
tissues of animals which consume the substance and that it eventually can
be passed on to humans through the food chain.
Vermeer et al. (1974) reported extensive loss of wildlife following
the application of sodium pentachlorophenate as a molluscicide in Surinam,
South America (Section D.5.1.2.2.3). Snails, frogs, fish, and snail kites
(a species of bird which feeds almost exclusively on snails) were found
dead following pentachlorophenol application to rice fields. The kite
mortality was attributed to consumption of snails which contained high
concentrations of pentachlorophenol. This report is the only documenta-
tion of pentachlorophenol effects in a terrestrial food chain. Low, but
detectable, pentachlorophenol levels were also found in other species of
birds, but it is not clear whether these residue levels were due to con-
sumption of other animals contaminated with pentachlorophenol or through
direct contact with the compound. Further investigations are needed on
the distribution of pentachlorophenol in plant and animal tissues, its
movement through the food chain, and the airborne contributions from both
agricultural applications and industrial sources.
D.8.3.2 Aquatic Ecosystems
Several studies on pentachlorophenol accumulation in aquatic orga-
nisms are available. In aquaria experiments, Kobayashi and Akitake (1975)
exposed goldfish to 0.1 mg pentachlorophenol per liter for 120 hr (Section
D.5.2.1.1). The fish concentrated the pentachlorophenol to a peak level
of 90 mg/g of tissue, a concentration factor of 1000 over that of the
original medium. Rudling (1970) analyzed pentachlorophenol levels in fish
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from a lake receiving pulp mill wastes. They found that pentachlorophenol
levels in tissues ranged from 0.15 to 3.0 mg/g, representing concentration
factors from 150 to 1000 over the amounts of pentachlorophenol in the lake
water. Holmberg et al. (1972) found that pentachlorophenol accumulated in
the tissues of eels kept in a medium containing 0.1 mg sodium pentachloro-
phenate per liter for eight days. Most of the stored pentachlorophenol
was associated with lipids, and substantial amounts remained stored in the
tissues after 55 days in pentachlorophenol-free water (Section D.5.2.1.2).
The work of Lu and Metcalf (1975) is discussed extensively in Section
D.5.2.2.2.6. In a closed laboratory system, these investigators traced
the movement of pentachlorophenol through an aquatic food chain. The
highest level of the chain was the mosquito fish, which accumulated and
concentrated pentachlorophenol to a level 296 times that of the initial
medium. Zitko, Hutzinger, and Choi (1974) detected levels of pentachloro-
phenol in aquatic organisms from a geographical area where the compound
was not widely used. These studies indicate that accumulation and bio-
magnification of pentachlorophenol occur in the aquatic environment, and
it is possible that a similar situation also exists for terrestrial systems.
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SECTION D.8
REFERENCES
1. Casarett, L. J., A. Bevenue, W. L. Yauger, Jr., and S. A. Whalen.
1969. Observations on Pentachlorophenol in Human Blood and Urine.
Am. Ind. Hyg. Assoc. J. 30(4):360-366.
2. Duggan, R. E., and P. E. Corneliussen. 1972. Dietary Intake of
Pesticide Chemicals in the United States (III), June 1968 — April
1970. Pestic. Monit. J. 5(4):331-341.
3. Duggan, R. E., and G. Q. Lipscomb. 1969. Dietary Intake of Pesti-
cide Chemicals in the United States (II), June 1966 — April 1968.
Pestic. Monit. J. 2:153-162.
4. Holmberg, B., S. Jensen, A. Larsson, K. Lewander, and M. Olsson.
1972. Metabolic Effects of Technical Pentachlorophenol (PCP) on
the Eel Angu-illa anguilla L. Comp. Biochem. Physiol. B 43(1) :171-183.
5. Johnson, R. D., and D. D. Manske. 1976. Residues in Food and Feed:
Pesticide Residues in Total Diet Samples (IX). Pestic. Monit. J.
9:157-169.
6. Kobayashi, K., and H. Akitake. 1975. Studies on the Metabolism of
Chlorophenols in Fish: I. Absorption and Excretion of PCP by Gold-
fish. Bull. Jpn. Soc. Sci. Fish. 41(l):87-92.
7. Lu, P. Y., and R. L. Metcalf. 1975. Environmental Fate and Bio-
degradability of Benzene Derivatives as Studied in a Model Aquatic
Ecosystem. Environ. Health Perspect. 10:269-284.
8. Manske, D. D., and P. E. Corneliussen. 1974. Pesticide Residues
in Total Diet Samples (VII). Pestic. Monit. J. 8(2):110-124.
9. Rudling, L. 1970. Determination of Pentachlorophenol in Organic
Tissues and Water. Water Res. 4(8):533-537.
10. Vermeer, K., R. W. Risebrough, A. L. Spaans, and L. M. Reynolds.
1974. Pesticide Effects on Fishes and Birds in Rice Fields of
Surinam, South America. Environ. Pollut. 7(3)-.217-236.
11. Zitko, V., 0. Hutzinger, and P.M.K. Choi. 1974. Determination of
Pentachlorophenol and Chlorobiophenylols in Biological Samples.
Bull. Environ. Contain. Toxicol. 12(6) :649-653.
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PART E
ENVIRONMENTAL ASSESSMENT OF CHLOROPHENOLS
455
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PART E - ENVIRONMENTAL ASSESSMENT OF CHLOROPHENOLS
Gary A. Van Gelder
University of Missouri — Columbia
Columbia, Missouri
E.I INTRODUCTION
This environmental assessment of chlorophenols follows the organiza-
tional format of Parts A-D of this document. The discussion is divided
into three groups of chlorophenol compounds: (1) monochlorophenols and
dichlorophenols, (2) trichlorophenols and tetrachlorophenols, and (3)
pentachlorophenol. Monochlorophenols and dichlorophenols are primarily
used as intermediates in the synthesis of other products. Trichlorophenols
are used directly as antimicrobial agents as well as intermediates in the
synthesis of other chemicals. Tetrachlorophenols and pentachlorophenol
are used extensively as fungicides for control of sap stain and for wood
preservation. Evaluation of the environmental impact of the many products
containing chlorophenol moieties, some of which are used extensively, is
beyond the scope of this document. Additionally, the chemical processes
used to produce chlorophenols also form a number of other contaminants,
including other chlorophenols, hexachlorobenzene, chlorodibenzo-p-dioxins,
chlorodibenzo-p-furans, and phenoxyphenols. The scientific evaluation of
the environmental impact of these compounds is a separate task. A com-
mittee within the U.S. Environmental Protection Agency is presently review-
ing the toxicology of chlorodioxins. This assessment focuses primarily on
the toxicity and biological activity of chlorophenols.
E.2 MONOCHLOROPHENOLS AND DICHLOROPHENOLS
E.2.1 PRODUCTION, USES, AND POTENTIAL ENVIRONMENTAL CONTAMINATION
E.2.1.1 Production
2-Chlorophenol can be synthesized by diazotization of 2-chloroaniline,
direct chlorination of phenol, or hydrolysis of 1,2-dichlorobenzene. The
most common process is direct chlorination of phenol, yielding both 2- and
4-chlorophenol. 2-Chlorophenol is separated by fractional distillation.
2,4-Dichlorophenol is produced by direct chlorination of phenol or by
further chlorination of 4-chlorophenol. Small amounts of 2,6-dichloro-
phenol and 2,4,5-trichlorophenol are also produced.
Production figures for 2-chlorophenol and 2,4-dichlorophenol are
considered proprietary. Some indication of the volume produced can be
obtained by looking at production of the herbicide 2,4-dichlorophenoxy-
acetic acid (2,4-D). Production of 2,4-D has been reported at various
times to be from 24,000 to 38,000 metric tons per year.
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E.2.1.2 Uses
Most of the 2-chlorophenol presently produced is used as an inter-
mediate in the synthesis of higher chlorophenols, which limits its dis-
tribution in the environment primarily to point sources. A possible
concern stems from its past use in fire-retardant varnishes and in cotton
fabrics to increase rot resistance and crease recovery. Presently, bromide
compounds are substituted for chlorophenols, but changes in use patterns
could occur if the bromide compounds are also found to cause toxicologic
problems. 2,4-Dichlorophenol is used as an intermediate in the manufac-
ture of pesticides.
E.2.1.3 Losses to the Environment
2,4-Dichlorophenol occurs both as a contaminant in the herbicide
2,4-D and as a degradation product of 2,4-D. Consequently, 2,4-dichloro-
phenol is present in the environment whenever 2,4-D is used. The break-
down of 2,4-dichlorophenol occurs within a few days, which is faster
than the degradation rate of 2,4-D. Consequently, 2,4-dichlorophenol is
not expected to accumulate in the environment. Although chlorophenols
are capable of being dispersed to the atmosphere through volatilization,
no investigations have been made on their presence, movement, fate, or
persistence in air.
Wastewater from the manufacture of phenoxyalkanoic herbicides has
been found to contain lower chlorophenols in amounts ranging from 68 to
125 mg/liter (Sidwell, 1971). Data on levels of lower chlorophenols in
runoff from agricultural and urban watersheds are not available. Two
incidents of groundwater contamination from the discharge of chlorophenol
wastes have been reported (Walker, 1961). One occurred in California
where wastes entered a local sewage system, and the other was at the
Rocky Mountain Arsenal in Colorado where wastes were discharged into un-
lined lagoons or were pumped into deep injection wells.
E.2.2 ENVIRONMENTAL PERSISTENCE
E.2.2.1 Physical and Chemical Properties
2-Chlorophenol is a light amber—colored liquid at room temperature
and has a pungent medicinal odor. The molecular weight is 128.56. The
melting point is 9°C and the boiling point is 175°C. The vapor pressure
is 1 mm Hg at 12°C. It is slightly soluble in water (2.85 g per 100 g)
and more soluble in ethanol, ether, and benzene.
2,4-Dichlorophenol exists as colorless crystals at room temperature.
It has an unpleasant, persistent odor similar to iodoform and a molecular
weight of 163.01. It melts at 45°C and boils at 210°C. The vapor pres-
sure is 1 mm Hg at 63°C. The solubility of 2,4-dichlorophenol in water
is low, but it is very soluble in many organic solvents.
2-Chlorophenol can undergo several chemical reactions, including
further chlorination, bromination, iodation, and nitration. Condensation
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reactions with formaldehyde produce phenolic resin intermediates or
methylene bridged polymers. Under proper conditions the hydroxyl group
may ionize, and in the presence of alkali metals metallic salts are
formed. 2,4-Dichlorophenol also undergoes halogenation and nitration in
the 6 position; further chlorination yields 2,4,6-trichlorophenol. Reac-
tions with formaldehyde yield condensation products that are methylene
bridged dimers. Salt formation is accomplished by reaction with alkali
metals. The volatility of 2-chlorophenol and 2,4-dichlorophenol is likely
a major dispersal mechanism of these chemicals in the atmosphere; however,
monitoring data are lacking.
Although sorption of 2,4-dichlorophenol on clay minerals is insignifi-
cant (Aly and Faust, 1964), it can be sorbed to a large extent by ion-exchange
resins (Aly and Faust, 1965). In general, strongly basic anion-exchange
resins sorb more of the chemical than cation exchangers. Activated carbon
has been used for removing low levels of chlorophenols and other organic
compounds from water (Eichelberger, Dressman, and Longbottom, 1970).
Because chlorophenols may be found on surfaces where they are exposed
to sunlight, they are susceptible to photochemical degradation. Aly and
Faust (1964) demonstrated the rapid decomposition of an aqueous solution
of a sodium salt of 2,4-D and 2,4-dichlorophenol exposed to ultraviolet
light. Plimmer and Klingebiel (1971) studied the products of riboflavin-
sensitized photodecomposition of 2,4-dichlorophenol in water irradiated
at a wavelength of 280 nm. Major products identified were dimeric com-
pounds; no dioxins were detected. Therefore, it seems unlikely that diox-
ins are formed from 2,4-dichlorophenol in aquatic systems.
E.2.2.2 Analytical Methods
The classic technique for analysis of chlorophenols in water is the
4-aminoantipyrine colorimetric method. This method is quite sensitive
and easy to use, but it is nonspecific because the aminoantipyrine reacts
with several isomers of chlorophenols to produce the same color.
Gas-liquid chromatography employing either electron capture or flame
ionization is the most widely used technique for separating, identifying,
and quantifying chlorophenols in various kinds of samples. This method
is sensitive to nanogram levels and is adequate for the quantitation of
chlorophenols. Biological samples such as animal and plant tissues re-
quire more extensive preparation than water samples before they are suit-
able for gas-liquid chromatographic analysis. Problems of poor resolution
and tailing encountered in some samples can be corrected by judicious
selection and preparation of column substrates (Kawahara, 1971; Karapally,
Saha, and Lee, 1973; Shafik, Sullivan, and Enos, 1973; Baird et al., 1974).
Because gas-liquid chromatography can detect nanogram quantities, con-
tamination must be avoided by following proper techniques in sample
collection, storage, and processing. Samples should be sealed and stored
at low temperatures, preferably below freezing. Acidification with H3POA
and CuSOz, followed by refrigeration at 5°C to 10°C has been recommended
for preservation of wastewater samples for phenol analysis (Rand, Greenberg,
and Taras, 1976). Extraction and cleanup procedures for a variety of
materials are available. The most common cleanup method is column
chromatography.
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E.2.2.3 Biological Degradation
Microbial decomposition appears to be the dominant mechanism for
dissipation of chlorophenols in soils. Bacteria isolated from soils,
including those known to degrade phenoxyacetic herbicides, are capable
of metabolizing chlorophenols (Bollag, Helling, and Alexander, 1968;
Evans et al., 1971; Spokes and Walker, 1974). Soil bacteria found to
be active in 2,4-dichlorophenol decomposition include Arthrobacter sp.
and Pseudomonas sp.
2-Chlorophenol disappears from soil with a half-life of less than
10 days following initial exposure and about twice as fast following
subsequent exposures. 2,4-Dichlorophenol disappears completely from
soil in 5 to 9 days; it disappears more rapidly than 2,4-D, which dis-
appears in 30 days. The complete degradation involves ring cleavage and
formation of succinic and, presumably, acetic acids. Although 2-chloro-
phenol and 2,4-dichlorophenol appear to be short-lived in soils, the data
are incomplete; factors affecting their persistence need further study.
Soil factors affecting sorption are pH, moisture, and the amount of clay
and organic matter. Information on sorption of 2,4-dichlorophenol by
organic matter is not available; therefore, its activity can only be in-
ferred from studies on acidic pesticides such as 2,4-D. Acidic pesti-
cide sorption to organic soil colloids is controlled by the pH of the
system (i.e., sorption is greater under acidic conditions).
Fungi have been suspected to possess the ability to metabolize
chlorophenols. Walker (1973) isolated a phenol-utilizing strain of
Rhodotorula gluti-ni-s from a Rothamsted soil. It has not been determined
if fungal strains are capable of utilizing chlorophenols as sole carbon
sources and if degradation pathways of fungal metabolism are similar to
those of bacterial metabolism.
Secondary treatment of sewage involves the removal of organic matter
from wastewater by biological processes. Because 2-chlorophenol and
2,4-dichlorophenol are easily biodegradable, secondary treatment should
provide excellent removal of these chemicals. Most of the chlorophenols
are likely to decompose in the aeration lagoon. Optimum temperature for
degradation of 2-chlorophenol in activated sludge appears to be between
25°C and 27°C, and optimum pH ranges from 6.5 to 8.0. Degradation was
uninhibited at concentrations of 2,4-dichlorophenol up to 100 mg/liter
(Ingols, Gaffney, and Stevenson, 1966). Neither 2-chlorophenol nor
2,4-dichlorophenol normally appear to pose a serious hazard in exposed
waste treatment facilities; ready degradation by microbial populations
in activated sludge and aeration lagoon effluent has been demonstrated.
2-Chlorophenol may persist longer due to direct or indirect toxic effects
if wastes containing high levels are discharged into an unacclimated body
of water.
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E.2.3 EFFECTS ON LOWER LIFE FORMS
E.2.3.1 Effects on Bacteria, Fungi, and Algae
Both 2-chlorophenol and 2,4-dichlorophenol are bactericidal, fungi-
cidal, and algicidal agents. In general, bactericidal and algicidal
potency appears to increase with increased chlorine substitution of the
parent phenol up to the trichlorophenol isomers. 2-Chlorophenol starts
to have an effect on the chlorophyll content of algae (blue-green algae,
Chlovella pyrenoidosa) at 10 mg/liter. At 500 mg/liter chlorophyll
synthesis is inhibited. 2,4-Dichlorophenol is more toxic; concentra-
tions of 100 mg/liter inhibit chlorophyll synthesis.
2-Chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol are more
potent antibacterial agents than phenol. A concentration of 25 mg
2,4-dichlorophenol per liter inhibits the growth of Pseudomonas sp. At
high concentrations chlorophenols act as gross protoplasmic poisons. At
lower concentrations specific enzyme systems are inhibited. Concentra-
tions of 0.015% to 0.030% of 2-, 3-, or 4-monochlorophenol inhibit the
growth of Aspergillus niger.
E.2.3.2 Effects on Plants
The phytotoxicity of 2-chlorophenol to vascular plants has not been
described, nor is information available on its distribution and trans-
port in vascular plants. The metabolism of chlorophenoxyacetic acids
to chlorophenols occurs in many plant species.
2,4-Dichlorophenol inhibits root growth in flax seedlings, cell
expansion in wheat coleoptiles, and the growth-stimulating effect of
indoleacetic acid in wheat (Volynets and Pal'chenko, 1972). The LC50
of 2,4-dichlorophenol for the aquatic plant Lerrtna minor is 40 mg/liter.
Additional information on phytotoxic properties is not available.
Very little information is available on the translocation and dis-
tribution of 2,4-dichlorophenol in vascular plants. Both oats and soy-
bean will absorb 2,4-dichlorophenol from nutrient solutions and soil
(Isensee and Jones, 1971). 2,4-Dichlorophenol was not found in the
mature oat seed, but small quantities were found in the soybean seed.
Oat seedlings concentrated 2,4-dichlorophenol in amounts up to nine
times the soil level, but soybean shoots contained about the same level
as the soil. Plant tissues were evaluated on a dry-weight basis. 2,4-
Dichlorophenol applied to leaves of soybeans is not translocated. More
than 98% of the 2,4-dichlorophenol applied was lost, probably due to
volatilization, within 72 hr of application. Although 2,4-D and 2,4-
dichlorophenol residues were found in rice plants during the first month
after herbicide application, rice grains contained neither herbicide nor
metabolite (2,4-dichlorophenol) when the plants reached maturity.
2 4-Dichlorophenol affects root mitosis in the European broad bean
(Viciafdbd) (Amer and All, 1969). Roots grown in a solution containing
62.5 mg 2,4-dichlorophenol per liter showed a decreased mitotic index
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and an increased frequency of induced mitotic anomalies including cyto-
mixis, stickiness, lagging chromosomes, formation of anaphase bridges,
and fragmentation effects. Spraying Vicia faba for five days with 7 ml
of a solution of 0.39 mg 2,4-dichlorophenol per liter caused mitotic
abnormalities in pollen mother cells (Amer and Ali, 1974). Similar
results were obtained when seeds were soaked in the same solution and
planted and pollen mother cells were obtained from the resulting plant.
Muhling et al. (1960) demonstrated that concentrations of 2,4-
dichlorophenol greater than 60 mg/liter inhibited spindle formation in
root cells of pea seedlings (Pisum sativwn') . The resulting chromosome
configurations were similar to those produced by the mitotic inhibitor
colchicine.
Information on the biotransformation of 2,4-dichlorophenol by plants
is scanty. There is some evidence of 2,4-dichlorophenol detoxication
through glycoside conjugation.
There is no evidence that plants are exposed to significant levels
of monochlorophenols or dichlorophenols except as a result of intentional
herbicide use. Accidental exposures are likely to be rare and limited
in scope. If groundwater or irrigation water were contaminated, then
phytotoxicity data would be useful in decision making.
E.2.4 EFFECTS ON ANIMALS
E.2.4.1 Effects on Fish and Other Aquatic Organisms
Data on the toxicity of 2-chlorophenol to aquatic organisms are
sparse. The 48-hr LC50 for bluegill (Leporrris macvooh-Lvus) is 8.1 mg/liter,
and for rainbow trout (Salmo gairdnei*i) the 96-hr LC50 is 2.6 mg/liter.
The 48-hr LC50 for Daphnia magna is 7.4 mg/liter. 2,4-Dichlorophenol at
16.3 mg/liter decreases cell division in sea urchin eggs (Arbaeia
punctulata). The 48-hr LC50 of 2,4-dichlorophenol in Daphnia magna is
2.6 mg/liter.
Accidental spills into water would be expected to result in fish
kills. The primary environmental concern is adequate processing of
chemical waste streams to remove chlorophenols.
E.2.4.2 Effects on Birds, Wildlife, and Domestic Animals
No information was found on the metabolism or toxicologic effects of
2-chlorophenol or 2,4-dichlorophenol in birds, wildlife, or domestic
animals. Sheep and cattle fed 2,4-D at levels of 60 mg/kg for 28 days,
held for 7 days, and then killed contained 0.07 to 1.06 ppm 2,4-dichloro-
phenol in the kidney and 0.15 to 0.31 ppm 2,4-dichlorophenol in the liver
(Clark et al., 1975). Levels of 2,4-D were similar to levels of 2,4-
dichlorophenol in the liver but were higher in the kidney. Levels of
2,4-dichlorophenol in fat were less than 0.05 ppm, which is the detection
limit, thus indicating that 2,4-dichlorophenol is not stored to any ex-
tent in body fat. Bjerke et al. (1972) reported that 2,4-dichlorophenol
does not occur in milk from cows fed high levels of 2,4-D.
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2,4-Dichlorophenol was found in egg yolk at levels of 0.1 to 0.6
ppm after chickens were fed a diet containing 100 to 800 mg nemacide
(0-(2,4-dichlorophenyl)C>,C>-diethyl phosphorothioate) per kilogram of
feed for 55 weeks (Sherman, Beck, and Herrick, 1972). Residues of 0.3
to 0.5 ppm 2,4-dichlorophenol were also found in the liver but not in
breast muscle of the hens. Biotransformation, elimination, kinetics,
and toxicologic effects were not described.
E.2.4.3 Effects on Laboratory Animals
The oral LD50 for 2-chlorophenol in the rat, mouse, and fox ranges
from 440 to 670 mg/kg. Clinical signs include restlessness, increased
respiration, tremors, convulsions, motor weakness, and coma. Lesions
include kidney damage, fatty liver, hemorrhages, and necrosis in the
stomach and intestine. 2-Chlorophenol is a convulsant with seizures
occurring 1 to 2 min after intraperitoneal injection. 2-Chlorophenol
appears to be a weak uncoupler of oxidative phosphorylation. Dogs
eliminate 2-chlorophenol in the urine primarily as sulfuric and glu-
curonic conjugates. The chronic toxicity has not been reported. A
90-day, multiple-level feeding study with rodents would be the first
step in filling this data gap.
The oral LD50 for 2,4-dichlorophenol is 580 mg/kg in the rat and
1600 mg/kg in the mouse. 2,4-Dichlorophenol has been fed to mice for
six months at levels of 100 or 230 mg/kg. The 100 mg/kg dose was con-
sidered to be a no-effect level. There is no evidence to suggest that
2,4-dichlorophenol is a convulsant.
The metabolites or biotransformation products of 2,4-dichlorophenol
have not been reported for humans or experimental animals. The only
information on the metabolism of 2-chlorophenol and 2,4-dichlorophenol
is derived from studies on chlorobenzene, lindane, and nemacide where
2-chlorophenol and 2,4-dichlorophenol occur as degradation products.
Studies on 1,2,3,4,5,6-hexachlorocyclohexane in mice have shown the
elimination of sulfate and glucuronide conjugates of 2,4-dichlorophenol
in the urine. 2,4-Dichlorophenol is a metabolite of 1,2,3,4,5,6-hexa-
chlorocyclohexane. The results indicate that 2,4-dichlorophenol is
rapidly eliminated.
E.2.5 EFFECTS ON HUMANS
There is no direct information on the toxicity of 2-chlorophenol or
2,4-dichlorophenol in humans. The individual most likely to be exposed
is the industrial worker, except for exposure of the general population
to minute quantities of these chlorophenols which occur in the environ-
ment as degradation products of other compounds.
E.2.4.6 TERATOGENICITY, MUTAGENICITY, AND CARCINOGENICITY
Mutagenic and teratogenic effects have not been studied. 2-Chloro-
phenol and 2,4-dichlorophenol have skin tumor-promoting activity similar
to that of phenol when tested in mice following a single initiating dose
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of dimethyIbenzanthracene. The lack of information on the carcinogenic-
ity of these chlorophenols is considered to be the most significant
data gap for monochlorophenols and dichlorophenols.
E.2.7 RESIDUES IN FOOD AND WATER
Data indicate that contamination of food with 2-chlorophenol or
2,4-dichlorophenol is minimal, although 2,4-dichlorophenol has occasion-
ally been reported as a food contaminant. 2,4-Dichlorophenol has been
reported in potato tubers (Bristol et al., 1974). The levels reported
are low, infrequently found, and are not cause for concern.
Dichlorophenols have been implicated as compounds contributing to
the objectionable phenolic odor and taste of water. The threshold odor
and taste concentration for 2,4-dichlorophenol is 2 to 8 ug/liter (2 to
8 ppb). The formation of chlorophenols during the chlorination of drink-
ing water has been reported (Burttschell et al., 1959). 2-Chlorophenol
can be converted to 2,4-dichlorophenol and 2,6-dichlorophenol; 2,4-
dichlorophenol can proceed further to form 2,4-6-trichlorophenol.
E.3 TRICHLOROPHENOLS AND TETRACHLOROPHENOLS
E.3.1 PRODUCTION, USES, AND POTENTIAL ENVIRONMENTAL CONTAMINATION
E.3.1.1 Production
There are two trichlorophenol isomers and one tetrachlorophenol
isomer of commercial interest: 2,4,6- and 2,4,5-trichlorophenol and
2,3,4,6-tetrachlorophenol. Other tetrachlorophenol isomers are 2,3,4,5-
and 2,3,5,6-tetrachlorophenol. 2,4,6-Trichlorophenol is formed by the
direct chlorination of phenol. 2,4,5-Trichlorophenol is produced through
the hydrolysis of 1,2,4,5-tetrachlorobenzene. Both isomers can also be
produced by diazotization of the corresponding trichloroaniline isomer.
2,3,4,6-Tetrachlorophenol and 2,3,4,5-tetrachlorophenol can be produced
by direct chlorination of phenol or by further chlorination of lower
chlorophenols. 2,3,4,5-Tetrachlorophenol can also be formed by diazoti-
zation of 2,3,4,5-tetrachloroaniline or hydrolysis of pentachlorobenzene.
2,3,5,6-Tetrachlorophenol can be synthesized from 2,3,5,6-tetrachloro-
aniline or as a coproduct with 2,3,4,5-tetrachlorophenol in the hydroly-
sis of pentachlorobenzene.
Production figures for trichlorophenols and tetrachlorophenols have
not been reported in recent years. The fact that large amounts are prob-
ably produced can be inferred from production figures from 1965 to 1968,
when from 1,817 to 12,742 metric tons of 2,4,5-trichlorophenol was pro-
duced each year. Because data from recent years have not been made
available, trends in production cannot be assessed.
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E.3.1.2 Uses
2,4,6-Trichlorophenol is used as a bactericide and fungicide in the
preservation of wood, leather, and glue and in the treatment of mildew
on textiles. It is also used as an ingredient in the preparation of
insecticides and soap germicides. The primary use of 2,4,5-trichloro-
phenol is as an intermediate in the synthesis of pesticides such as the
herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) or the insecticide
ronnel. 2,4,5-Trichlorophenol is also used as a germicide and as an
ingredient in soap germicides. 2,3,4,6-Tetrachlorophenol is used as a
preservative for wood, latex, and leather and also as an insecticide,
2,3,4,5-Tetrachlorophenol and 2,3,5,6-tetrachlorophenol have not been
used commercially.
E.3.1.3 Environmental Residues
Data are lacking on the presence of trichlorophenols and tetrachloro-
phenols in the environment. The presence of microbiological degradation
mechanisms may mean that residues do not exist to any appreciable extent.
Another possibility is that general environmental contamination has not
been evaluated. Data on levels of trichlorophenols and tetrachlorophenols
in the air are not available.
Trichlorophenols disappear in a few days from aerated lagoons or
activated sludge systems; therefore, it is unlikely that a significant
contamination problem would occur as long as wastewaters are treated
(Ingols, Gaffney, and Stevenson, 1966; Sidwell, 1971). Trichlorophenols
at levels of 2 to 20 mg/liter have been reported in wastewater from an
industrial plant manufacturing herbicides (Sidwell, 1971). The contri-
bution of runoff to chlorophenols in water following herbicide use has
not been evaluated.
Trichlorophenols enter the environment through their use as fungi-
cides or as degradation products of the herbicides 2,4,5-T and silvex
[2-(2,4,5-trichlorophenoxy)propionic acid]. Tetrachlorophenols enter
the environment as a result of their use as fungicides to preserve wood.
Also, commercial pentachlorophenol, which is used extensively as a wood
preservative, contains 4% to 10% tetrachlorophenol.
Many commonly used organochlorine compounds are degraded by mammals
to yield higher chlorophenols. Compounds that result in trichlorophenol
degradation products include 2,4,5-T; silvex; alpha, beta, gamma, and
delta isomers of hexachlorocyclohexane; ronnel; pentachlorobenzene; and
trichlorobenzene. Compounds yielding tetrachlorophenol degradation prod-
ucts include y-hexachlorocyclohexane (lindane), tetrachlorobenzene,
pentachlorobenzene, and pentachlorophenol. Exposure to one of these com-
pounds can result in trace residues of chlorophenols in animals or humans.
For example, Johnson and Manske (1976) reported on pesticide residues in
360 food composites found in a Food and Drug Administration market basket
survey from 1972 to 1973. Pesticides which degrade to chlorophenols were
found as follows: pentachlorophenol in 9 composites at levels of 10 to
20 ppb, lindane in 39 composites at levels of 0.3 to 6.0 ppb, ronnel in
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2 composites at trace levels, and 1,2,3,4,5,6-hexachlorocyclohexane in
59 composites at levels of 0.2 to 5.0 ppb. If these low-level residues
are degraded in humans to lower chlorophenols, the resulting levels will
be even lower and, based on present evidence, are of no identifiable
health concern.
E.3.2 ENVIRONMENTAL PERSISTENCE
E.3.2.1 Chemical and Physical Properties
The molecular weight of trichlorophenols is 197.46. 2,4,6-Trichloro-
phenol melts at 68°C, boils at 246°C, and has a vapor pressure of 1 mm Hg
at 76.5°C. 2,4,5-Trichlorophenol melts at 66°C and sublimes at 245°C;
its vapor pressure is 1 mm Hg at 72°C. Trichlorophenols are slightly
soluble in water and very soluble in organic solvents.
Water-soluble salts of 2,4,6- and 2,4,5-trichlorophenol and 2,3,4,6-
tetrachlorophenol are readily prepared. Trichlorophenols and tetrachloro-
phenols are weak acids. It has been shown that 2,4,5-T will photodecompose
to form 2,4,5-trichlorophenol, which, in turn, forms a colored polymeric
product (Crosby and Wong, 1973). Leopold, van Schaik, and Neal (1960)
reported charcoal absorption properties for 18 chlorinated phenoxyacetic
acids. One, two, or three chlorine substitutions increased absorptive
properties.
E.3.2.2 Analytical Methods
Sample extraction and cleanup methods are available for a variety of
sample matrices. Gas-liquid chromatography, the most widely used technique
for separating, identifying, and quantifying chlorophenols in various kinds
of samples, is sensitive at nanogram levels. Either electron-capture or
flame-ionization detectors are used. Other methods include colorimetry,
thin-layer chromatography, ultraviolet and infrared spectrophotometry,
and mass spectrometry. Problems of poor resolution and tailing can be
corrected by judicious selection of columns and type of derivatization.
With the known toxicity of the trichlorophenols and tetrachlorophenols,
present analytical methods are adequate.
E.3.2.3 Biological Degradation
Microbial degradation appears to be a major elimination mechanism.
Bacterial species capable of metabolizing 2,4,6-trichlorophenol and
2,3,4,6-tetrachlorophenol have been isolated from soil and activated
sludge (Tabak, Chambers, and Kabler, 1964; Nachtigall and Butler, 1974).
The metabolic pathways have not been outlined, and the extent to which
such bacteria are present in the environment is not known. Under experi-
mental conditions, 2,4,6-trichlorophenol at concentrations of 50 to 100
ppm inhibits oxygen uptake in mixed microbial populations but has no
effect at 1 to 10 ppm. The importance of this effect on sewage treat-
ment processes is unknown.
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Three isomers of tetrachlorophenol (2,3,A,5-, 2,3,5,6-, and
2,3,4,6-) have been shown to disappear from soil to a large degree in
four weeks (Ide et al., 1972). Several genera of bacteria are capable
of metabolizing chlorophenols (Chambers, Tabak, and Kabler, 1963;
Tabak, Chambers, and Kabler, 1964). 2,4,5-Trichlorophenol is more
resistant to soil microbial degradation than is 2,4,6-trichlorophenol,
and 2,4,5-T is more resistant than 2,4,5-trichlorophenol. One major
source of 2,4,5-trichlorophenol in soil is as a breakdown product of
2,4,5-T; as long as 2,4,5-T is not present, it is unlikely that 2,4,5-
trichlorophenol will be present as a result of using 2,4,5-T.
Kearney, Woolson, and Ellington (1972) incubated soil with 2,4,5-
trichlorophenol and reported no evidence of microbial condensation to
chlorodioxins. Sidwell (1971) reported that wastewater treatment by a
combined lagoon and stabilization pond removed 87% to 94% of the chloro-
phenols. Soil sorption characteristics of trichlorophenols and tetra-
chlorophenols have not been studied.
E.3.3 EFFECTS ON LOWER LIFE FORMS
E.3.3.1 Effects on Bacteria,Fungi, and Algae
2,4,6-Trichlorophenol is about 24 times more effective as a bacteri-
cide than is phenol. Some research has demonstrated that 2,4,6-trichloro-
phenol affects bacterial membrane permeability. Similar studies with
2,4,5-trichlorophenol have not been reported.
2,4,5-Trichlorophenol inhibits growth of bacteria at concentrations
of 10 to 400 mg/liter. The test organism, Pseudomonas aevuginosa, was
more resistant than other organisms tested. Bacteria capable of metabo-
lizing 2,4,6-trichlorophenol have been isolated from soil and activated
sludge. 2,4,5-Trichlorophenol inhibits a number of fungal species at
concentrations of 2 to 5 mg/liter (ppm). Most fungi are inhibited at
concentrations around 10 ppm.
In one study, 99 of 116 fungi isolated from poultry litter metabo-
lized tetrachlorophenols, as evidenced by a loss of tetrachlorophenols
from the culture (Gee and Peel, 1974). Twenty-two of the 26 fungal
species metabolized tetrachlorophenols at rates ranging from 4% to 100%
in five days. Some fungi both metabolized tetrachlorophenols and formed
chloroanisoles. Bacteria isolated from poultry litter have been shown
to completely metabolize 2,3,4,6-tetrachlorophenol in five days without
the production of chloroanisole. Aerobic conditions were required.
2,4,5-Trichlorophenol and 2,4,6-trichlorophenol inhibit chlorophyll
synthesis in Chlorella pyrenoidosa (blue-green algae) at concentrations
greater than 2.5 mg/liter (2.5 ppm). Concentrations of 1 mg/liter have
only a minimal effect. These compounds pose a threat to algae in waste
stabilization ponds.
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E.3.3.2 Effects on Plants
Information on the effects, biotransformation, and elimination of
trichlorophenols and tetrachlorophenols in plants is not available. No
dose-response data have been reported for vascular plants. Blackman,
Parke, and Carton (1955) reported the following LC5o values for the
aquatic plant Lerma minor: 0.6 mg/liter 2,3,4,5-tetrachlorophenol,
1.6 mg/liter 2,4,5-trichlorophenol, and 5.9 mg/liter 2,4,6-trichloro-
phenol. In another study, 2,4,6-trichlorophenol had no effect on plants
when tested for eight months at concentrations of 0.01 to 4.1 mg/liter
(Manufacturing Chemists Association, 1972). The data gap in this area
would be important if irrigation water became contaminated.
E.3.4 EFFECTS ON ANIMALS
E.3.4.1 Effects on Aquatic Organisms
No information is available on the toxicity of 2,4,5-trichloro-
phenol to aquatic organisms. The 96-hr median tolerance limit of 2,4,6-
trichlorophenol for the fathead minnow is 0.6 mg/liter. Other reliable
data are not available. Acute aquatic toxicity studies are needed to
fill this data gap.
E.3.4.2 Effects on Birds
The fungal metabolism of chlorophenols to chloroanisoles in chicken
litter has caused an economic problem in England. The meat and eggs
acquire a musty taint. There is no expected health hazard because the
meat and eggs are unpalatable. This problem can largely be avoided by
not using wood shavings treated with sap-stain control agents contain-
ing chlorophenols (Curtis et al., 1974).
E.3.4.3 Effects on Mammals
E.3.4.3.1 General Considerations — 2,4,5-Trichlorophenol and 2,4,6-
trichlorophenol are absorbed from the gastrointestinal tract. Skin con-
tact can result in erythema, edema, and chemical burning. Apparently,
2,4,5- and 2,4,6-trichlorophenol do not penetrate intact skin in suffi-
cient amounts to result in systemic toxicity. 2,3,4,6-Tetrachlorophenol
dissolved in organic solvents can be absorbed through intact skin in
toxic amounts. Data on the rate of uptake of trichlorophenols and
tetrachlorophenols are not available.
E.3.4.3.2 Effects on Domestic Animals — No toxic effects were
reported in cattle fed 2,4,5-trichlorophenol at levels of 18 or 159
mg/kg for 78 days and 53 mg/kg for 154 days (Anderson et al., 1949).
Feed consumption and weight gain were unaffected.
Because 2,4,5-trichlorophenol is a metabolite of 2,4,5-T, additional
insight on the toxicity of 2,4,5-trichlorophenol can be obtained from
studies in which 2,4,5-T was fed to animals. Cattle were fed 2,4,5-T
at levels from 10 to 1000 mg/kg feed (Bjerke et al., 1972). Lactating
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cows fed 1000 mg 2,4,5-T per kilogram of feed for 21 days eliminated
0.2 to 1.0 ppm 2,4,5-T and 0.15 to 0.25 ppm 2,4,5-trichlorophenol in
milk. Levels in milk decreased to less than 0.05 ppm for both 2,4,5-T
and 2,4,5-trichlorophenol within 3 days after feeding was stopped. At
feeding levels of 100 mg/kg, 2,4,5-T did not appear in milk and 2,4,5-
trichlorophenol was present at 0.05 to 0.07 ppm. Based on available
data, there should be no significant residue problem with low-level
exposure of cattle to these compounds.
Sheep were fed 2,4,5-T for 28 days at the rate of 60 mg/kg (Clark
et al., 1975). 2,4,5-Trichlorophenol residues were found in muscle
(0.13 ppm), liver (6.1 ppm), and kidney (0.9 ppm) but not in fat.
Tissue residues of 2,4,5-T decreased markedly during a 7-day withdrawal
period, but 2,4,5-trichlorophenol levels did not decrease as rapidly.
Additional information on the kinetics and biotransformation of these
compounds in domestic animals is not available.
E.3.4.3.3 Effects on Laboratory Animals — In the rat the oral LD50
for 2,4,5-trichlorophenol ranges from 820 to 2900 mg/kg and for 2,4,6-
trichlorophenol from 820 to 2800 mg/kg. In the rat and mouse the LD50
for 2,3,4,6-tetrachlorophenol administered by the oral, subcutaneous, or
intraperitoneal route ranges from 120 to 250 mg/kg. 2,4,6-Trichloro-
phenol has convulsant properties. 2,4,5-Trichlorophenol and 2,3,4,6-
tetrachlorophenol do not cause convulsions but result in hypotonia.
High doses of 2,4,5-trichlorophenol cause diarrhea. Feeding rabbits
20 doses of 1 or 10 mg 2,4,5-trichlorophenol per kilogram over 28 days
did not result in toxicosis (McCollister, Lockwood, and Rowe, 1961).
Doses as high as 500 mg/kg resulted in only slight kidney and liver
changes. Rats fed 10, 30, or 100 mg/kg did not know toxicologic changes.
Dosages of 300 or 1000 mg/kg resulted in minor histopathologic changes
in kidney and liver. The mouse excretes 2,4,6-trichlorophenol in the
urine as sulfate and glucuronide conjugates. The kinetics for elimina-
tion have not been described.
Trichlorophenols inhibit oxidative phosphorylation but to a lesser
degree than tetrachlorophenols and pentachlorophenol. Tetrachlorophenols,
like pentachlorophenol, causes hyperpyrexia. Trichlorophenols cause
only small elevations in body temperature. Death from trichlorophenols
and tetrachlorophenols results in rapid onset of rigor mortis, which also
has been reported with pentachlorophenol.
E.3.5 EFFECTS ON HUMANS
Human systemic poisoning with 2,4,5- and 2,4,6-trichlorophenol and
tetrachlorophenols has not been reported. The industrial worker is
most likely to be exposed to trichlorophenols. Information on general
population exposure is unavailable. The lower chlorophenols have not
been reported in food, but they may be present in water as a result of
chlorination.
The manufacturing process for trichlorophenols or products manu-
factured from trichlorophenol intermediates has resulted in the formation
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of the highly toxic contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin.
2,3,7,8-Tetrachlorodibenzo-p-dioxin is a potent chloroacnegenic agent.
Chloracne has occurred in industrial plants manufacturing trichloro-
phenols. Improved manufacturing processes have resulted in much lower
2,3,7,8-tetrachlorodibenzo-p-dioxin levels in trichlorophenol products.
The commercial process used and the methods for destroying dioxins are
patented. The toxicology of dioxins is beyond the scope of this assess-
ment of chlorophenols and is an issue that should be considered separately.
E.3.6 CARCINOGENICITY AND TERATOGENICITY
Innes et al. (1969) reported that the oral administration of 2,4,6-
trichlorophenol to mice yielded ambiguous results; additional studies
are needed. 2,4,6-Trichlorophenol applied to the skin of mice along with
an initiating dose of dimethylbenzanthracene did not produce tumors
(Boutwell and Bosch, 1959). 2,4,5-Trichlorophenol with dimethylbenzan-
thracene produced tumors, but 2,4,5-trichlorophenol alone did not. Addi-
tional research is needed to fill this data gap.
2,4,5-Trichlorophenol was not teratogenic in mice or rats at doses
of 0.9 or 9.0 mg/kg (Neubert and Dillmann, 1972). No information on the
teratogenicity of 2,4,6-trichlorophenol or tetrachlorophenols was found;
research is needed.
E.3.7 STANDARDS AND REGULATIONS
No standards or regulations dealing with trichlorophenols or tetra-
chlorophenols were found.
E.4 PENTACHLOROPHENOL
E.4.1 PRODUCTION, USES, AND POTENTIAL ENVIRONMENTAL CONTAMINATION
E.4.1.1 Production
Pentachlorophenol has been produced in significant quantities since
the 1930s. Production in 1972 was 23 million kilograms; current pro-
duction is an estimated 25 million kilograms. Pentachlorophenol is formed
by the chlorination of phenol. Catalysts used include iron, aluminum, or
antimony chlorides. Presently, pentachlorophenol is produced at four
locations in the United States; very little is imported. One U.S. pro-
ducer has indicated an intent to discontinue manufacture.
E.4.1.2 Uses
About 90% to 95% of the pentachlorophenol used in the United States
is for the preservation of wood. Technical grade pentachlorophenol
typically contains 4% to 10% tetrachlorophenol. In 1975, 244 million
cubic feet of wood were treated with some type of preservative. Of this
amount, 60 million cubic feet were treated with pentachlorophenol. The
greatest uses of pentachlorophenol-treated wood are for poles, lumber,
and fence posts.
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Pentachlorophenol is used in either the water-insoluble phenol form
or as the water-soluble sodium salt, sodium pentachlorophenate. Penta-
chlorophenol is used as a herbicide, a preharvest desiccant, an algicide,
a molluscicide, and for slime and mold control in food processing plants
and pulp mills. It is also used as a fungicide in the processing of
cellulosic products, starches, adhesives, paints, leathers, oils, rubber,
textiles, and wooden crates used for packaging raw agricultural products.
E.4.1.3 Losses to the Environment
Because the primary use of pentachlorophenol is in the preservation
of wood, pentachlorophenol is intentionally applied to focal areas in
the environment. Its use as a herbicide, except for small quantities
in spot treatments, appears to be limited at this time. Its use as a
molluscicide is also limited. The continued use of pentachlorophenol
as a general herbicide or molluscicide should be reconsidered in the
context of current practices and alternatives.
There are no reliable data on pentachlorophenol emissions from
manufacturing plants. Ifeadi (1975) estimated losses in the manufactur-
ing process to range from 0.55 to 2.16 kg/metric ton. Losses to the
environment at the manufacturing site need to be quantified.
Pentachlorophenol also enters the environment from the several
hundred wood treating plants in North America. The principal route is
surface drainage into waterways. There is also some atmospheric loss
due to vaporization, but these losses have not been quantitated. An
indicator of significant losses would be damage to green plants in the
area or fish kills. Pentachlorophenol has been found in water draining
from wood treating plants (Thompson and Dust, 1971; Bevenue et al., 1972).
Treated wood can serve as a point source. Studies have shown that
pentachlorophenol-oil solutions migrate down the vertical axes of poles,
and some solution leaves the wood at ground level. Contamination is
limited to the few inches of soil immediately adjacent to the pole.
Losses are highest from freshly treated wood, but such losses are usually
of no consequence. Occasionally, sensitive ornamental plants are damaged
when freshly treated poles or lumber are used immediately adjacent to
them. Under field conditions, grasses or other plants are usually seen
growing around the pole or fence post.
E.4.1.4 Environmental Residues
Pentachlorophenol is present at low levels in the environment. It
was found in the urine of nonoccupationally exposed persons at a level
of 0.01 to 0.2 ppm (Casarett et al., 1969). One study found an average
level of 26.3 ppb in human fat (Shafik, 1973). Levels in the range of
0.05 to 0.3 ppm in the blood plasma of nonoccupationally exposed persons
have also been reported (Casarett et al., 1969).
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Bevenue, Ogata, and Hylin (1972) reported 2 to 284 ng pentachloro-
phenol per liter (2 to 284 ppt) in rainwater and 14 ppt in snow. Penta-
chlorophenol has been reported in drinking water at levels of 0.1 to 0.3
ppb (0.1 to 0.3 yg/liter) (Buhler, Rasmusson, and Nakaue, 1973; Arsenault,
1976). Buhler, Rasmusson, and Nakaue (1973) reported pentachlorophenol
levels of 0.1 to 0.7 ppb in river water, and levels of 0.01 to 10 ppb
were reported by Goto (1971) in rivers of Japan.
Zitko, Hutzinger, and Choi (1974) reported pentachlorophenol resi-
dues of 1 to 10 ppb in fish and bird eggs obtained from a marsh or aquatic
environment. Pentachlorophenol residues of 150 to 200 ppb were reported
by Rudling (1970) in fish from a lake receiving pulp mill wastes. Levels
in eels were 3000 ppb. Fish have been shown to accumulate and concentrate
pentachlorophenol by factors of 150 to 1000 (Rudling, 1970; Holmberg et
al., 1972; Lu and Metcalf, 1975; Glickman et al., 1977; and Pruitt,
Grantham, and Pierce, 1977). There appear to be species differences in
the ability of fish to concentrate pentachlorophenol.
Pentachlorophenol was found in the Food and Drug Administration
market basket survey samples at a frequency of 1.4% to 3.3% (Duggan and
Corneliussen, 1972). The resulting human intake was estimated to be
1 to 6 yg per person per day.
From the above information, it is apparent that parts-per-trillion
to parts-per-billion levels of pentachlorophenol are present in the
environment. Clearly, the manufacture and use of pentachlorophenol
contribute to these residues; however, there are other potential sources.
Arsenault (1976) reported that 10 ppm chlorine can chlorinate 1 ppm of
naturally occurring phenol, yielding approximately 0.2 ppb pentachloro-
phenol. Considerable evidence shows that chlorination results in the
formation of lower chlorinated phenols, but the report by Arsenault
(1976) is the only one suggesting that pentachlorophenol may be generated
by municipal chlorination. This experiment needs to be replicated.
Evidence also exists that pentachlorophenol may be a degradation product
of other chemicals, including hexachlorobenzene and lindane (Lui and
Sweeney, 1975; Mehendale, Fields, and Matthews, 1975; Engst, Macholz,
and Kujawa, 1976; Engst et al., 1976; Kohli et al., 1976). The quanti-
tation of these degradation pathways and the contribution of these
metabolic products to overall pentachlorophenol residues require further
study.
E.4.2 ENVIRONMENTAL PERSISTENCE
E.4.2.1 Physical and Chemical Properties
In the pure state pentachlorophenol is a white, crystalline solid
with a molecular weight of 266.35 and a vapor pressure at 20°C of
0.00011 mm Hg. Its water solubility is 14 ppm (14 mg/liter) at 20°C.
It is soluble in alcohols, ethers, and various organic solvents, and
is commonly dissolved in aromatic hydrocarbons, heavy oils, or light
solvents such as mineral spirits when it is used to treat wood. The
melting point is 190°C and the boiling point is 293°C.
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A monovalent alkali metal salt of pentachlorophenol which is water
soluble can be formed; most commonly this salt is sodium pentachloro-
phenate. Pentachlorophenol is quite stable. It does not decompose when
heated at temperatures up to its boiling point (293°C) for extended
periods. Pure pentachlorophenol is considered to be rather inert chemi-
cally. At pH 5 or lower, pentachlorophenol is nonionized.
Pentachlorophenol is lost from treated wood slowly. Early losses
from wood can result from migration of the carrier solvent. Treated
wood retains pentachlorophenol for years, as evidenced by the preserva-
tion of wood for 30 years or more. The rate of pentachlorophenol loss
varies with the solvent system. Pentachlorophenol mixed with soil and
placed in a glass jar with only a paper cover persisted for 5 years
(Hetrick, 1952).
Pentachlorophenol disappears rapidly from aerated solutions, pre-
sumably by vaporization. Pentachlorophenol undergoes photodecomposition
and forms a variety of products (Munakata and Kuwahara, 1969). The
degradation products show stronger fungicidal properties but weaker
phytotoxic and fish-killing activities than pentachlorophenol.
E.4.2.2 Analytical Methods
The most widely used, effective technique for analysis of penta-
chlorophenol in many sample types is electron-capture gas-liquid chroma-
tography. Confirmation techniques include ultraviolet and infrared
spectrophotometry as well as mass spectroscopy. Current detection limits
of nanogram to picogram quantities are sufficient in view of the toxicity
of the compound.
E.4.2.3 Biological Degradation
Pentachlorophenol is an organic molecule and its ultimate fate under
aerobic conditions should be degradation to chlorine, carbon dioxide, and
water. Bacterial metabolism and detoxification of pentachlorophenol
occurs in the environment and in the laboratory. Certain soil bacteria
detoxify pentachlorophenol by methylation to form pentachloroanisole
(Cserjesi, 1972). Chu and Kirsch (1972, 1973) isolated a bacterial strain
from a continuous-flow enrichment culture which metabolized pentachloro-
phenol as a sole source of organic carbon and energy. Others have cul-
tured bacteria that biodegrade significant quantities of pentachlorophenol
(Kirsch and Etzel, 1973; Watanabe, 1973). Adding pentachlorophenol to
soil results in an increase in the number of pentachlorophenol-decomposing
microorganisms (Watanabe, 1973). Suzuki (1977) reported that Pseudomonas
sp. (bacteria) released 14C02 when [1I*C]pentachlorophenol was added to
cultures. Other metabolites included tetrachlorocatechol and tetrachloro-
hydroquinone. Certain fungi have also been shown to methylate penta-
chlorophenol to form pentachloroanisole (Curtis et al., 1974).
Mobility and persistence in soils depends on the physical and chemi-
cal characteristics of the soil as well as on the microbiological popula-
tion. Soil factors include temperature, moisture, soil type, organic
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matter content, free iron oxides, clay minerals, sorptivity, and cation-
exchange capacity. The interrelationships among these factors are com-
plex. Adequate soil moisture increases pentachlorophenol degradation;
pentachlorophenol is relatively stable in dry soils. Persistence is
longer in heavy-clay soils and in soils with low organic content. Steri-
lizing soil samples has been shown to stop the degradation of penta-
chlorophenol. Under what might be considered natural field conditions,
there is 90% degradation in 30 to 50 days.
Sidwell (1971) demonstrated that less than 1% of added pentachloro-
phenol was present after 30 hr in an aerated lagoon secondary wastewater
treatment system. Other experiments have been performed with activated
sludge treatment of wastewater from wood preserving plants. The system
degrades pentachlorophenol, but shock loading of municipal plants is a
potential problem. Each situation must be considered separately. Evi-
dence suggests that pentachlorophenol-containing wastewaters can be
successfully treated.
E.4.3 EFFECTS ON LOWER LIFE FORMS
E.4.3.1 Effects on Bacteria, Fungi, and Algae
Pentachlorophenol and sodium pentachlorophenate are well-known,
widely used antimicrobial substances. Inhibition of bacterial and fungal
growth occurs at concentrations from less than 1 ppm up to 2500 ppm
(mg/liter). Typical inhibitory concentrations range from 10 to 80 ppm.
Some fungi show tolerance to pentachlorophenol concentrations up to 100
ppm. Fortunately, these fungi do not produce wood decay. Pentachloro-
phenol is toxic to algae. Levels of 2 to 20 ppm inhibit growth.
E.4.3.2 Effects on Plants
Pentachlorophenol has been used as a herbicide. Small amounts of
pentachlorophenol applied to leaves will migrate to the stalk and to
other leaves in sugar cane. Sugar cane will also take up pentachloro-
phenol from a nutrient media. Most (99%) of the pentachlorophenol was
in the roots with the remainder in the stalk and suckers. There is some
evidence that sugar cane roots metabolize pentachlorophenol (Hilton,
Yuen, and Nomura, 1970). Pentachlorophenol is also translocated in
cotton plants (Miller and Aboul-Ela, 1969).
Pentachlorophenol is toxic to plants, but there are species dif-
ferences in susceptibility. In the past, greenhouse flats have been
treated with pentachlorophenol, but this practice is generally not recom-
mended. Pentachlorophenol-treated wooden posts or stakes have been used
to support plants in orchards. Adverse effects result if the stakes are
freshly treated or if the wood is placed too close to the plant. Penta-
chlorophenol is also toxic to aquatic plants.
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E.4.4 EFFECTS ON ANIMALS
E.4.4.1 Effects on Fish
Fish kills have occurred when sufficiently high levels of penta-
chlorophenol effluents have entered waterways. There is considerable
variation in the susceptibility of different aquatic organisms, with
levels ranging from 20 to 9500 ppb. In general, the 96-hr LC50 values
are on the order of 32 to 340 ppb for salmon, trout, bluegill, and fat-
head minnows. Some of the variation in reported values results from
different experimental methodologies. The chronic toxicity of penta-
chlorophenol to fish has not been determined. Whole-body tissue resi-
dues in fish killed by pentachlorophenol ranged from 30 to 60 ppm
(Vermeer et al., 1974).
Biomagnification of pentachlorophenol has not been demonstrated in
the environment but has been shown in the laboratory by Lu and Metcalf
(1975). The highest trophic level was the mosquito fish. The ecologic
magnification factor for pentachlorophenol was 296 versus 16,950 for
DDT, 1312 for aldrin, and 29 for nitrobenzene. The rapid elimination of
pentachlorophenol from most organisms probably contributes to the rela-
tively low magnification even though pentachlorophenol is rapidly absorbed,
Lu and Metcalf (1975) reported that pentachlorophenol was a degradation
product of hexachlorobenzene in their model aquatic ecosystem.
Several studies have demonstrated that fish rapidly take up penta-
chlorophenol from the water. Fish have the ability to accumulate penta-
chlorophenol to levels 100 to 1000 times the ambient water level. Highest
levels are found in blood, gills, hepatopancreas, gallbladder, kidney,
heart, and skin. Muscle has lower levels than do most other tissues.
Contaminated fish placed in clean water rapidly eliminate a major portion
of the residue. Most studies have been for short durations, but some
evidence suggests a longer retention of lower-level residues. Present
data are inadequate to define the long-term toxicokinetics in fish, and
additional research is needed. Future studies should consider effects
of the water pH, which has a significant effect on ionization of
pentachlorophenol.
E.4.4.2 Effects on Birds
Few studies on the toxicity of pentachlorophenol to birds have been
reported. In one field investigation, dead birds were found in a rice
field treated with sodium pentachlorophenate (Vermeer et al., 1974).
Analysis of tissues showed pentachlorophenol levels of 11.3 ppm in brain,
45.6 ppm in liver, and 20 ppm in kidney. Similar birds intentionally
shot a few days later showed residues of less than 1 ppm in the same
tissues; this is circumstantial evidence that birds also eliminate penta-
chlorophenol rapidly. Hill et al. (1975) reported dietary lethal con-
centrations (LCSO) for pentachlorophenol to be 3400 to 5200 ppm for
bobwhite, Japanese quail, pheasant, and mallard duck.
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Another economic problem is caused by the development of a musty
taint in muscle and eggs of chickens. This problem apparently results
when treated wood shavings are used for bedding. Fungi in the litter
methylate tetrachlorophenols and pentachlorophenols to the corresponding
anisoles (Curtis et al., 1972, 1974).
E.4.4.3 Effects on Mammals
E.4.4.3.1 General Considerations — Pentachlorophenol can be absorbed
dermally, orally, or by inhalation. The acute lethal dose for all species
tested is 100 to 200 mg/kg. The solvent used can affect the toxicity.
The lethal multiple dose is 50 to 70 mg/kg. The toxicity of inhaled penta-
chlorophenol has not been adequately studied, and research should be done
on this route of uptake.
Levels of 125 to 250 ppm pentachlorophenol in food cause adversion
to the food by cats. In rats levels of 300 to 600 ppm result in decreased
food consumption; levels of 30 to 60 ppm are eaten with little effect on
food intake. Peak blood levels are reached 3 to 12 hr after ingestion.
Most of the pentachlorophenol in blood is found in the plasma, with only
small amounts in red blood cells. Pentachlorophenol is primarily excreted
in the urine with a half-life of 1.5 to 4 days. The metabolites formed
vary with different species. Evidence suggests that small amounts of
pentachlorophenol may bind to plasma proteins and that enterohepatic
circulation may prolong elimination. The mechanism of action involves
the uncoupling of oxidative phosphorylation.
E.4.4.3.2 Effects on Domestic Animals — Domestic animals may be
exposed to pentachlorophenol through gross negligence of the livestock
owner who allows animals, especially cattle, to drink pentachlorophenol
solutions or by casual contact with pentachlorophenol-treated wood in
fences, feed bunks, bunker silos, and farm buildings. The direct con-
sumption of pentachlorophenol solutions has caused death in animals;
cattle are the species most likely to consume the solution. The half-
life of pentachlorophenol in the blood of cattle is less than 2 days;
surviving animals should not be slaughtered for 30 days after an acute
exposure.
One important factor affecting the toxicity of pentachlorophenol in
domestic animals is the carrier solvent used in treating wood. Apparently,
a variety of hydrocarbons with high solubility for pentachlorophenol are
used as cosolvents. From a toxicologic viewpoint, the types of oils and
organic solvents used are not adequately specified; thus, it is not possi-
ble to determine the contribution of the solvent to the toxicity of penta-
chlorophenol. This is an area that needs study, particularly concerning
carrier solvents used to treat wood that has a high probability of coming
into significant contact with humans or animals.
With the exception of acute accidental exposures, the most serious
incidents of documented pentachlorophenol toxicity to animals resulted
from placing sows in farrowing crates or individual farrowing houses
constructed of freshly treated lumber. Such practices have resulted in
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sow and piglet deaths. Using weathered lumber or adequate bedding pre-
vents the problem. There did not appear to be any serious long-term
health effects in surviving animals placed in clean environments.
More recently, it has been recognized that cattle may be exposed to
low levels (<1 mg/kg) of pentachlorophenol by eating out of feed bunks
constructed of treated wood, licking treated wood, or eating silage or
other feed stored immediately adjacent to treated wood. The greater the
tendency of the wood to bleed (i.e., the oil solution oozes to the sur-
face), the higher will be the exposure. More attention to the type of
wood treatment and uses of treated wood can prevent these low-level
exposures. Dermal exposure is possible when cattle rub against treated
boards or poles, but this route of exposure has not been documented nor
quantitated. Such exposure would likely be minimal. Pentachlorophenol
levels have not been measured in the air of animal housing containing
pentachlorophenol-treated lumber. Consequently, respiratory exposure
has not been quantitated. Studies monitoring these levels should be
conducted. Calculations based on vapor densities show that the respira-
tory exposures should be low.
The acute lethal toxicity of pentachlorophenol in swine, sheep, and
cattle is on the order of 140 to 160 mg/kg. Multiple doses at 35 to 70
mg/kg cause weight loss or decreased weight gain. Recovery occurs after
termination of exposure. Long-term feeding studies in domestic animals
at low levels of exposure have not been reported; studies are warranted
in this area.
Acute dermal effects consisting of inflammation and necrosis have
been observed in swine lying directly on freshly treated wood. Lesions
observed at necropsy in acutely poisoned animals include renal edema and
hemorrhage, generalized congestion of viscera, and inflammation in the
digestive tract. Death occurs rapidly following a period of collapse
and rapid breathing. Rigor mortis occurs in minutes instead of hours.
E.4.4.3.3 Effects on Laboratory Animals — The acute toxicity of
pentachlorophenol to laboratory animals has been determined. In general,
the oral LD50 values for rats, rabbits, and guinea pigs range from 70 to
300 mg/kg. The oral LD50 for aqueous solutions of sodium pentachloro-
phenate is 200 mg/kg; oil solutions of pentachlorophenol have an approxi-
mate LD50 of 140 mg/kg. The type of oil used affects the toxicity; the
lowest LDSO (27 mg/kg) was from oral administration of a fuel oil solu-
tion containing 0.5% pentachlorophenol. The dermal lethal dose ranges
from 40 to 200 mg/kg for pentachlorophenol and from 100 to 300 mg for
sodium pentachlorophenate. The acute and chronic toxicities of inhaled
pentachlorophenol have not been adequately reported; this area is an
important void in the toxicologic information requiring immediate
attention.
Chronic oral toxicity studies with rats have been reported by
several investigators. One of the issues addressed in these studies has
been the determination of the contribution of nonphenolic contaminants
to the toxicity of pentachlorophenol. Pentachlorophenol is available
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commercially as technical pentachlorophenol containing 9 to 27 ppm
hexachlorodibenzo-p-dioxin, 90 to 135 ppm heptachlorodibenzo-p-dioxin,
and 500 to 2500 ppm octachlorodibenzo-p-dioxin or as technical penta-
chlorophenol with a low nonphenolic content (containing less than 60 ppm
total dioxins). These studies have helped to identify no-effect levels
as well as to define toxic levels and effects that aid in determining
the toxicologic hazard associated with pentachlorophenol exposure.
Rats can tolerate rather remarkably high doses of pentachlorophenol
for extended periods. Kimbrough and Linder (1975) fed rats technical
and pure pentachlorophenol at levels of 1000 ppm (50 mg/kg) for 90 days.
This dose is about one-third to one-fourth of the typical single-dose
LD50 value. Rats fed pure pentachlorophenol showed some liver cell en-
largement. The group fed technical pentachlorophenol had more liver
cell changes, including foamy cytoplasm, single hepatocellular necrosis,
and slight interstitial fibrosis.
Several adequately designed 90-day chronic toxicity studies have
been reported. Knudsen et al. (1974) fed male and female rats technical
pentachlorophenol in the diet at levels of 25, 50, and 200 ppm, which
are equivalent to approximate dosage rates of 1.5, 3, and 14 mg/kg
respectively. The authors considered 25 ppm to be the no-effect level.
Liver enzyme induction occurred at 200 ppm. Hemoglobin and erythrocyte
counts were depressed at 50 ppm in male rats, but no hematologic effects
were observed at any dose in female rats. Liver pathology was limited
to centilobular vacuolization, which was also seen to a lesser extent in
controls.
Goldstein et al. (1977) demonstrated in an eight-month feeding
study with rats that technical pentachlorophenol induced liver aryl
hydrocarbon hydroxylase and glucuronyl transferase at feeding levels of
20 ppm (about 1.2 mg/kg) or higher. Pure pentachlorophenol was not a
potent enzyme inducer; only the 500 ppm level increased glucuronyl trans-
ferase. Although biologic effects were observed, feeding levels of 500
ppm (about 30 mg/kg) for eight months was not particularly debilitating.
Kociba et al. (1971) compared the toxicities of technical penta-
chlorophenol and a 95/5 mixture of purified pentachlorophenol and tetra-
chlorophenol. They found a decrease in hemoglobin, erythrocyte count,
and packed cell volume in male rats fed 30 mg technical pentachloro-
phenol per kilogram for 90 days. The purified 95/5 mixture had less
biological effect than technical pentachlorophenol. For the 95/5 com-
pound, 3 mg/kg produced no effect, and 10 mg/kg caused only a relative
increase in liver weight. For technical pentachlorophenol, 3 mg/kg
produced a small increase in serum alkaline phosphatase which was not
apparent at 10 mg/kg. Knudsen et al. (1974) also found an increase in
alkaline phosphatase at 1.5 and 14 mg/kg but not at 3 mg/kg. In the
Kociba et al. (1971) study, 3 mg technical pentachlorophenol per kilo-
gram caused a relative increase in liver and kidney weights; 10 mg/kg
increased absolute liver weight.
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479
Kociba et al. (1973) fed male and female rats pentachlorophenol
with low nonphenolic content for 90 days. The no-effect level was 10
mg/kg in females and 3 mg/kg in males. The effects produced at 30 mg/kg
were limited to changes in liver and kidney weights. Changes in liver
and kidney weights are a biological response to large amounts of a toxi-
cant that must be metabolized by the liver and excreted by the kidney.
In all of the above studies the histopathologic lesions were minimal.
Schwetz et al. (1976, 1978) fed male and female rats pentachloro-
phenol with a low nonphenolic content for 22 or 24 months respectively.
The no-effect level was 3 mg/kg in females and 10 mg/kg in males. As
with the other studies cited, feeding 30 mg/kg for 22 or 24 months did
not result in any life-impairing effects. The authors concluded that
pentachlorophenol was not carcinogenic.
Pentachlorophenol is a commercial poison used because of its long-
term stability as a wood preservative; therefore, it is fortunate that
even high exposure rates for long periods do not result in serious health
effects. Although some changes in clinical chemistry and hematologic
parameters have been shown, the magnitude of the changes was small. The
nonphenolic content of technical pentachlorophenol increases its biologic
activity in rats primarily through liver enzyme induction and increases
in liver weight. Based on current data, the inadvertant exposure of
animals or humans to microgram per kilogram levels of pentachlorophenol
is not expected to result in any detectable adverse toxicologic effects.
E.4.5 EFFECTS ON HUMANS
E.4.5.1 Exposure Factors
E.4.5.1.1 General Population — The literature indicates that at
least some segments of the general population are exposed to low levels
of pentachlorophenol. Pentachlorophenol has been found in 1% to 3% of
food composites in market basket surveys; estimated daily exposures
ranged from 1 to 6 yg per person for the years 1965 to 1969 (Duggan and
Corneliussen, 1972). Pentachlorophenol was found in drinking water at
60 ppt in Oregon (Buhler, Rasmusson, and Nakaue, 1973). The origin of
the pentachlorophenol is unclear; some evidence shows that chlorination
of water will result in the chlorination of naturally occurring phenols
(Arsenault, 1976). Pentachlorophenol was also found in sewage influent
and effluent (Buhler, Rasmusson, and Nakaue, 1973).
Casarett et al. (1969) reported pentachlorophenol in plasma (0.05
to 1 ppm) and urine (0.01 to 10 ppm) of nonoccupationally exposed per-
sons in Hawaii. Shafik (1973) found an average of 26.3 ppb pentachloro-
phenol in 18 human fat samples of unspecified origin. Cranmer and Freal
(1970) reported levels of 2 to 11 ppb in urine from the general popula-
tion. No adverse health effects have been ascribed to these exposure
levels. The findings of Braun, Blau, and Chenoweth (1978) showing that
a 0.1 mg/kg dose in humans results in a steady-state plasma level of
0.49 ppm, the results of laboratory animal studies, and the minimal
effects reported in higher occupational exposures suggest that present
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480
levels of exposure will not result in adverse health effects. Addi-
tionally, it is not known to what extent the present pentachlorophenol
residues in humans result from use of pentachlorophenol as a commercial
poison, from water chlorination, or from degradation of compounds such
as lindane or hexachlorobenzene.
E.4.5.1.2 Industrial Workers — Four groups of industrial workers
have varying degrees of exposure to pentachlorophenol. The first is the
rather small group of workers employed in the three or four chemical
plants actually manufacturing pentachlorophenol. Industrial hygiene
programs are operational in these plants. Summary reports have not
indicated any serious health problems, although dermal sensitivity was
noted in some instances. Exposure factors have not been reported. The
trend in the industry has been toward reducing exposure by use of bulk
handling systems and formulation of large solid pentachlorophenol blocks.
Insufficient information is available in the open literature to fully
assess this situation.
The second group includes workers involved in formulating and pack-
aging pentachlorophenol for particular uses. No information was found
regarding the extent of this type of industrial exposure.
The third group consists of workers in several hundred wood treat-
ing plants using pentachlorophenol. Some wood treatment plants are
operated by large organizations with an awareness of good industrial
hygiene. Other wood treating facilities are small, low-volume companies,
and there is very little information on their hygiene practices and worker
exposure. Pentachlorophenol has been identified in the air in wood treat-
ing plants. Levels of pentachlorophenol in air have ranged from 0.006 to
0.297 mg/m3 (Wyllie et al., 1975; Arsenault, 1976). The highest value
represents the maximum level that occurs when a pressure treating cylinder
is opened. Typical air levels appear to be 0.01 to 0.02 mg/m3. Because
of limited data it is not known if these values are representative of
the industry or are unique to one situation.
Workers in two wood treating plants in Hawaii have been studied for
several years. Plasma levels of 1 to 20 ppm pentachlorophenol and urinary
levels of 1 to 20 ppm were found. Levels decreased rapidly when work ex-
posure was stopped for several days. A variety of medical tests showed
no significant adverse health effects following chronic exposures. Some
evidence of higher levels of serum glutamic-oxaloacetic transaminase,
serum glutamic-pyruvate transaminase, and lactic dehydrogenase enzymes
were reported (Klemmer, 1972); however, the values were not outside
normal ranges. A more detailed statistical analysis is in progress.
Takahashi et al. (1975) reported elevated levels of C-reactive protein
in plasma of chronically exposed workers. The relationship of this
occurrence to dermal or respiratory inflammation is unknown. There was
increased incidence of skin inflammation in the group exposed to penta-
chlorophenol. Some evidence suggests reversible effects on kidney func-
tion consisting of decreased creatinine clearance and phosphorus
reabsorption.
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481
The fourth group of workers at occupational risk are builders using
large amounts of treated wood. Skin irritation has occurred. Verbal
reports of irritating vapors have been made, but apparently the problem
has not been sufficient to result in a careful clinical case study,
documentation, and reporting. The role of solvent vapors in these
situations is also a factor that has not received attention. The use of
protective clothing and adequate ventilation apparently prevent or
resolve most of these problems.
E.4.5.2 Toxicity
Humans are potentially exposed to pentachlorophenol via dermal,
respiratory, and oral routes, and fatal pentachlorophenol toxicosis has
occurred. According to the literature, lethal exposures have resulted
from extensive dermal contact with pentachlorophenol solutions, inten-
tional ingestion, gross contamination of a container used to prepare
food, and, in several cases, inhalation of dust. As with other com-
mercial poisons, failure to observe good hygiene practices, to use common
sense, and to utilize protective clothing leads to excessive exposures
that can result in toxicosis.
There are instances recorded in which pentachlorophenol solutions
have been used in large quantities to treat wood surfaces inside of
houses. Often these have involved treating woods such as cedar and red-
wood which may not take up and hold the solution as well as other woods.
Adverse health effects have occurred as a result of breathing either
vapors or minute particles that result from pentachlorophenol blooming,
which occasionally occurs.
Pentachlorophenol is irritating to respiratory membranes and to skin.
Dermal exposures often involve contact with petroleum-based solvents; thus,
the contribution of pentachlorophenol versus the contribution of the
solvent to the resulting toxicologic response has not been determined.
Air concentrations greater than 1 mg/m3 cause painful irritation in the
upper respiratory tract and result in sneezing and coughing, particularly
in newly exposed individuals. Concentrations as high as 2.4 mg/m3 can
be tolerated by those conditioned to exposures.
Symptoms of both acute exposures and chronic high-level exposures
include general weakness, fatigue, dizziness, headache, anorexia, nausea
and vomiting, dyspnea, hyperpyrexia, respiratory distress, tachycardia,
and profuse perspiration. In addition, chronic poisoning may include
weight loss and hepatomegaly. Treatment of intoxications should include
administration of balanced intravenous fluids to promote renal excretion,
with close attention paid to acid-base balance and electrolytes (Haley,
1977). Exchange blood transfusions have been used in intoxicated babies
with apparent success (Robson et al., 1969).
Symptoms occur at blood levels of 40 to 80 ppm. Acute intoxications
have resulted in blood and tissue levels of 100 to 200 ppm. An oral dose
of 0.1 rag/kg resulted in a peak plasma level of 0.248 ppm, with a cal-
culated steady-state value of 0.491 ppm after eight days. Pentachloro-
phenol is primarily eliminated in the urine. Most of the chemical in
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482
the urine is unchanged pentachlorophenol, with lesser amounts of penta-
chlorophenol glucuronide. Small amounts of absorbed pentachlorophenol
are eliminated in the feces as pentachlorophenol and pentachlorophenol
glucuronide. The half-life for elimination is approximately 30 hr.
There is some speculation of a longer half-life for a low pentachloro-
phenol residue. Presently reported studies are inadequate to clarify
this point for one or more of the following reasons: (1) continuous
low-level exposure could have occurred, (2) the length of the study was
too short, or (3) the levels of exposure were low. If there is a long-
term retention of small amounts of pentachlorophenol, it may result from
specific high-affinity protein binding or enterohepatic circulation.
The available data indicate that pentachlorophenol does not have a long-
term accumulation and storage in body fat as do some other chlorinated
hydrocarbons.
E.4.6 TERATOGENIC AND CARCINOGENIC EFFECTS
Pentachlorophenol has not shown mutagenic activity in the Ames test
(Anderson, Leighty, and Takahashi, 1972), the host-mediated assay
(Buselmaier, RShrborn, and Propping, 1973), or the sex-linked lethal test
on drosophila (Vogel and Chandler, 1974). Schwetz et al. (1978) reported
that pentachlorophenol was not carcinogenic when fed to rats for 22 or
24 months. Innes et al. (1969) reported that technical pentachlorophenol
at a dietary level of 130 ppm was not tumorigenic in rats. Schwetz,
Keeler, and Gehring (1974) found both purified and technical pentachloro-
phenol to be embryotoxic and fetotoxic but not teratogenic in rats. The
no-effect level was 5 mg/kg.
E.4.7 STANDARDS AND REGULATIONS
The maximum concentration in air established by the American Indus-
trial Hygiene Association (1970) is 0.5 mg pentachlorophenol or 0.5 mg
sodium pentachlorophenate per cubic meter. There is a threshold limit
value for an 8-hr exposure. The Code of Federal Regulations 21, part 121,
paragraph 121:2556, allows up to 50 ppm pentachlorophenol in treated wood
intended for use in contact with food. A tolerance for pentachlorophenol
in food has not been established.
E.4.8 RECOMMENDATIONS
1. More information on accepted and safe uses of pentachlorophenol-
treated wood should be made available to the end user. Presently, anyone
can purchase treated wood at a lumber yard without being cautioned to
avoid skin contact or receiving information on herbicidal properties.
2. Research on the biologic fate of pentachlorophenol in fish and mammals
is needed to determine if long-term cellular or plasma-protein binding
occurs.
3. The toxicity of the solvents used to carry pentachlorophenol into
wood should be assessed.
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4. Ambient pentachlorophenol levels in air of closed livestock facilities
need to be determined in order to fully assess the potential hazard.
5. The sources of pentachlorophenol residues in food products should
be determined.
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48A
PART E
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492
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
i. REPORT NO.
EPA-600/1-79-012
I. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Reviews of the Environmental Effects of Pollutants:
XI. Chlorophenols
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
V. P. Kozak, G. V. Simsiman, G. Chesters, D. Stensby,
and J. Harkin
8. PERFORMING ORGANIZATION REPORT NO.
ORNL/EIS-128
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Information Center Complex/Information Division
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37830
10. PROGRAM ELEMENT NO.
1HA616
11. CONTRACT/GRANT NO.
IAG D5-0403
12. SPONSORING AGENCY NAME AND ADDRESS
Health Effects Research Laboratory, Cin-OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45219
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/10
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report is a review of the scientific literature on the biological
and environmental effects of chlorophenols. Included in the review are a
general summary and a comprehensive discussion of the following topics as
related to chlorophenols and specific chlorophenol compounds: physical and
chemical properties; occurrence; synthesis and use; analytical methodology;
biological aspects in microorganisms, plants, wild and domestic animals, and
humans; distribution, mobility, and persistence in the environment; assessment
of present and potential health and environmental hazards; and review of
standards and governmental regulations.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
*Pollutants
Chlorophenols
Toxicology
Health Effects
06F
06T
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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