EPA-560/8-75-001
ENVIRONMENTAL HAZARD ASSESSMENT REPORT
CHLORINATED NAPHTHALENES
DECEMBER 1975
ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF TOXIC SUBSTANCES
WASHINGTON, D,C, 2QwO
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PREFACE
Our society uses thousands of chemical substances, with many of
them released into the environment in varying quantities as production
or handling losses, as waste materials, or as a direct consequence of
their intended or unintended uses. Concern over possible effects of
these chemicals has prompted the establishment by the Early Warning
Branch of the Office of Toxic Substances of a program to review data on
the release, exposure, and effects of chemical substances in order to
assist in setting priorities for further study or possible regulatory
action.
Detailed analyses on every commercial chemical are not practical.
Selected materials are initially screened with a simple literature
search; a limited number of these chemicals are selected for more
detailed study. Criteria for this selection include volume of production,
manner of use, market growth potential, exposure patterns, detection in the
environment, known toxic effects, and functional or chemical relationships
to known environmental pollutants. Chlorinated naphthalenes were selected
for detailed study because of the serious occupational health problems
suffered by workers exposed to the compounds, cattle poisoning incidents
in the late 1940's and early to mid 1950's, 1972 production levels of
some five million pounds, and chemical similarities to polychlorinated
biphenyls. The early warning screening system uses diverse sources,
including opinions of experts, referrals from other units of government,
reports in. the scientific and trade literature, predictive modelling,
and public inquiries.
These hazard assessments are prepared from reviews of the subject
substances supplemented by additional searches and inquiries to obtain
the most complete and recent information available. Only data considered
pertinent to an assessment of environmental hazard are reported in this
series.
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Although the assessments use as complete an information base as
possible, additional information may be available or may become available.
Therefore, these assessments are subject to revisions. The Office of
Toxic Substances welcomes any additional pertinent data.
Recommendations in this document are those of the Office of Toxic
Substances and may not represent an Agency consensus. Nor do they
represent commitment to further action by the Environmental Protection
Agency or any other organization. Tradenames and manufacturers are
mentioned in this document for purposes of clarity and specificity only
and do not constitute an endorsement of any product.
This report was written by Frank D. Kover. The Environmental
Hazard Assessment Series is being prepared under the guidance of Dr.
Farley Fisher, Chief of the Early Warning Branch, Office of Toxic
Substances.
The literature review which preceded this assessment was conducted
by Dr. Philip Howard and Mr. Patrick Durkin of the Syracuse University
Research Corporation, Syracuse, New York. That review was supplemented
by consultations with selected knowledgeable individuals both within and
outside the Federal Government and is part of a report entitled Preliminary
Environmental Hazard Assessment of Chlorinated Naphthalenes. Silicones.
Fluorocarbons, Benzenepolycarboxylates, and Chlorophenols, available
through the National Technical Information Service, Springfield, Virginia
22151 (NTIS accession number - PB-238 074/AS).
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TABLE OF CONTENTS
PREFACE 1
LIST OF FIGURES iv
LIST OF TABLES iv
CONCLUSIONS AND RECOMMENDATIONS 1
SUMMARY OF TECHNICAL DISCUSSION 3
I. GENERAL INFORMATION ! 4
II. ENVIRONMENTAL EXPOSURE FACTORS 12
III. BIOLOGICAL EFFECTS 19
IV. HANDLING PRACTICES,STANDARDS,AND REGULATIONS 32
REFERENCES 33
-in-
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LIST OF FIGURES
Figure 1
Figure 2
Figure 3
Monochloronaphthalenes,
Suggested Route of Decomposition of
1-Chioronaphthalene by Soil Bacteria.,
Proposed Mechanisms of Naphthalene Di-
hydrodiol Formation in Mammalian and
Microbial Systems
5
16
17
Table I.
Table II.
LIST OF TABLES
Comparative Properties of Halowax
Chioronaphthalenes
Uses of Chlorinated Naphthalenes..
6
11
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Appreciation is expressed to the many individuals who provided
information and reviewed drafts of this report. Special appreciation
is expressed to the Office of Toxic Substances Staff, and to Dr. J.G.
Vos of the Institute of Veterinary Pathology, University of Utrecht, the
Netherlands, for valuable comments and information concerning European
work on chlorinated naphthalenes and related chlorinated hydrocarbon
compounds. Comments and suggestions incorporated into this report were
contributed by Guy Nelson, U.S. EPA/NERC-Corvallis; Dr. Donald I.
Mount, Director, EPA-National Water Quality Laboratory, Duluth; Dr.
Gilman Veith, EPA-National Water Quality Laboratory, Duluth; Dr. Gerald
Bowes, California Water Resources Board, Sacramento; John P. Lehman, EPA
Office of Solid Waste Management Programs, Hazardous Waste Management
Division, Washington, D. C.; George B. Morgan, EPA/NERC-Las Vegas; Dr.
Charles F. Jelinek, FDA, Bureau of Foods, Division of Chemical Technology,
Washington, D.C.; and Daniel F. McCarthy, U.S. International Trade
Commission (formerly U.S. Tariff Commission).
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CONCLUSIONS AND RECOMMENDATIONS
The largest use of the chlorinated naphthalenes employs the lower
chlorinated compounds in a temporarily "closed" system (automobile
capacitor). The extent to which these compounds leach out or are
otherwise released from the capacitor to the environment has not been
determined; should release occur, they are likely to be readily decomposed.
The more toxic higher chlorinated members of this class are produced
at the rate of a half million pounds per year. Whether or not these
compounds persist in the environment is unknown, but their chemical
similarities to polychlorinated biphenyls (PCBs) arouse some suspicion.
In addition, traces of higher chlorinated naphthalenes have been detected
in one species of water fowl in the Netherlands. Only two reports of
chlorinated naphthalenes in U.S. environmental samples have been cited.
Amounts of these compounds released to the environment as a result of
their use seem low.
Overall, the available information on the chlorinated naphthalenes
suggests that the potential environmental hazard associated with these
compounds warrants a moderate level of concern. The available monitoring
data from limited U.S efforts could represent just some isolated
contamination or indicate a more widespread problem that is just beginning
to be detected.
Recommendations
1. The environmental hazard posed by these chemicals should be reassessed
if: (a) chlorinated naphthalenes are detected with greater frequency
in environmental samples by FDA (food), EPA, or others; (b) production
levels of penta- and hexachloronaphthalenes double; or (c) new use(s) of
these compounds with higher exposure potential is proposed.
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2. The environmental persistence of the higher chlorinated naph-
thalenes should be determined.
3. Monitoring should be undertaken in the vicinities of electro-
plating activities discharges, waste oil discharges, electronic parts
manufacturing wastes, landfill disposal activities, as well as effluent
from the production plant. Samples should be taken from water sediments
since these compounds are water insoluble. Some of this monitoring might
be carried out in conjunction with future monitoring programs for PCBs
and chlorinated hydrocarbons, and particularly pesticides.
4. Further investigation to determine the environmental fate of the
penta- and hexachloronaphthalenes will be necessary if monitoring data
indicate their presence near electroplating activities.
5. The potential for chlorinated naphthalenes to undergo epoxi-
dation similiar to dieldrin has led to some concern about carcinogenic
implications. The metabolic fate of these compounds with regard to
epoxide formation should be determined.
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SUMMARY OF TECHNICAL DISCUSSJON
The chlorinated naphthalenes enjoyed large scale use prior to and
during World War II. Capacitor and cable manufacturers used them as
dielectrics and water repellents superior to paraffin wax. Other industrial
applications of that era included use as additives for high-pressure
lubricants, as wood preservatives, and as synthetic waxes and impregnants.
Today their major uses are confined to use as a paper impregnant in
automobile capacitors (dielectric), and as an oil additive to clean
sludge and petroleum deposits from engines. Two minor uses of potential
environmental significance are in the electroplating industry (stopoff
compounds) and in the fabric dyeing industry.
Available production and market information on these compounds
indicates that total production has declined somewhat over the last
decade and a half, probably at least in part due to severe occupational
skin problems (chloracne) associated with the higher chlorinated compounds,
especially the penta- and hexachloronaphthalenes. The lower chlorinated
naphthalenes (mono-, di-, tri-, and tetrachloronaphthalenes) form the
bulk of today's market and are not associated with severe toxic manifestations.
The levels of chlorinated naphthalenes which are important from a
toxicity standpoint show rather wide variation in toxic response from
species to species. In general it is somewhat useful to consider the
toxicity of the chlorinated naphthalenes to increase with the degree of
chlorination. The penta- and hexachloronaphthalenes elicit the most
severe toxic responses. Mono- and dichloronaphthalenes have relatively
low toxicity. One of the most susceptible animals is the cow.
The lack of homogeneity in human response has prevented the establishment
of a no-effect level. Industrial hygiene standards of 0.5 mg/m in air
3
for pentachloronaphthalene and 0.2 mg/m' for hexachloronaphthalene are
designed to minimize the incidence of chloracne and to prevent liver
damage.
A foreign report of traces of chlorinated naphthalenes in one
species of fish eating birds appears to demonstrate a potential for
bioaccumulation. Only two reports of detection in environmental samples
from the U.S. are known.
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I. GENERAL INFORMATION
Physical and Chemical Characteristics
In general, the chlorinated naphthalenes are water insoluble waxy
solids exhibiting a high degree of chemical and thermal stability. Their
physical properties vary with the degree of chlorination. The mono- and
dichloronaphthalenes are liquids at room temperature whereas the higher
chlorinated compositions are solids. As the chlorine content increases,
the specific gravity, boiling point, melting point, fire point and flash
point all increase while vapor pressure and water solubility decrease.
The structure of the chlorinated naphthalenes consists of the
naphthalene double ring where any or all of the eight hydrogen atoms can
be replaced with chlorine (C-mH/c) \C1 ) (Figure 1.). The commercial
products are generally mixtures with different degrees of chlorination
and the dominant species is indicated by the percent chlorine content
attributed to the product (Table I). No data from manufacturers are
available on the ratios among the structural isomers in the commercial
products. The commercial products are sold as refined chloronaphthalenes
(Table I) and as chloronaphthalene crudes. The product bulletin (Koppers,,
a) describes the crudes as having essentially the same physical properties
as the refined products, but "not held within close limits". It suggests
they are suitable for many applications where dark colors are acceptable.
Amounts of the crude forms produced are a minor portion of the total
production (Hoy, 1975). Possible impurities of these products are
chlorinated derivatives, corresponding to the impurities in coal tar, or
petroleum-derived naphthalene feedstock which may include biphenyls,
fluorenes, pyrenes, anthracenes, and dibenzofurans (Hunt and O'Neal, 1967).
Koppers' Research Department analyzed the company's naphthalene feedstock
(refined coal tar base) and did not detect any trace of biphenyls or
dibenzofurans (Hoy, 1975).
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FIGURE 1
MONOCHLOROHAPHTHALENES
Cl
1-chloronaphthalene
2-chloronaphthalene
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Tfl8LE E
COmPRRRTiVE PROPERTIES OF HflLOWflX CHLORONRPHTHflLENES
j (KOPPERS.a)
PRODUCT NUMBER
1 COMPOSITION |
2 PHYSICAL FORM ' \
3 CHLORINE CONTENT, % (Appioximate)
!@ 25°C
4 SPECIFIC GRAVITY >
!@ 60°C
!@- 30 MM
5 INITIAL BOILING POINTS, ~@ 100 MM
!>' 700 MM
.6 DISTILLATION RANGE!
7 SOFTENING POINT(Melting Point), °C(Approx.)
C.O.C •
9 Flii POINT, °C, C.O.C. •
10 SPECIFIC HEAT, Gm. Cal./Gm./°C
11 LAT!"tJT HEAT OF VAPORIZATION, Cal,/Gm.
12 COLOR
13 ACIDITY, MAXIMUM (Mg. of KOH/Gm.)
14 VISCOSITY, SAYBOLT UNIV. SEC. (APPROX.
200 Cms. with Surfr.ee! 9.5 Sq.
15 VOLATILITY '" '" 1° L"1V"?> Ro°m Tt"Ilp-
Gms./Sq. In/Hr. G>10r>°C'
1G PENETRATION, 200 Gm., 5 Sees. @> 25°C(Approx.)
8 FLASH POINT, °C
1 7 DIELECTRIC CONSTANT ! @~60 CYCLE'S/SEC.
t> i666cYci.es/sEc.
®> 60 CYCLES/SEC.
IB POWER FACTOR '"" "
(B> 1000 CYCLES/SEC.
19 RESISTIVITY, MEGOHM CENTIMETERS .
! 1031
Mono-Chlor
LIQUID
122
jl.20
—
;144°C
;IBO°C
250°C
. 654 Mux. 255°C
9656 Min. 26B°C
989i Mln. 275°C
1-25
\135
—
While to Pale Straw
0.05
35@25°C
1.0%
; 1000
Mono-+Di.Chlor
LIQUID
26
1.22
;144°C
; i8o°c
! 250°C
80% Mln. 282°C
90S Iviin. 300°C
'-33
130
0.40E> 50°
0.42& 100°
Whrto to Pali Straw
, 0.05
34 @ 25°C
'1.5%
• 1001
Trl-+Totra-Chlor
FLAKES
50
1.58
200°C
234°C
308°C
93
'200 •
1 Nono to Boiling
0.22<5> 15°
o.cr,
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TflBLEI (CONT.)
COmPflRflTIVE PROPERTIES OF HflLOWflX CHLORONfiPHTHflLENES~
(KOPPERS.a)
PRODUCT NUMBER
1. COMPOSITION
2. PHYSICAL FORM
3. CHLORINE CONTENT, %(Approximate)
• • 1© ?'~>°r
4 SPECIFIC GRAVITY ../,, .7
1 @ 60°C :
I@!':30MM
5. INITIAL BOILING POJ NTS! (@ 100 MM.
!@ 760MM
6. DISTILLATION RANGE
7. SOFTENING POINTlMelting Point), °C(Approx.)
B. FLASH POINT, °C, C.O.C.
*
,9. FIRE POINT, °C, C.O.C.
1
10. SPECIFIC HFAT, Gm. Cal./Gm7°C
11. LATENT HEAT OF VAPORIZATION, Cal./Gm.
12. COLOR'
13. ACIDITY. MAXIMUM (Mg. of KOH/Gm.)
14. VISCOSITY, SAYBOLT UNIV. SEC.IApprox.)
, 200'Gms. with Surface 9.6 Sq.
15 VOLATILITY '" "" '° D"V' * R°°m T<""D'
Gm«./Sq. In/Hr. S> 105°C
16. PENETRATION.200 Gm,5 Sec. @ 25°C(Approx.) '
17. DIELECTRIC CONSTANT '' , o 60 CVCLES/SEC.
e> 1000 CYCLES/SEC.
if 60 CYCLES/SEC.
18 POWER FACTOR ""
E> 1000 CYCLES/SEC.
19. RESISTIVITY, MEGOHM CENTIMETERS
,1013
'Tatra-tPanto-Chlor
IFLAKES
:56
1.67
:222°C
'258°C
328°C
•
1120
1 230
, Nono to Boiling •
! Light Yellow
.0.05
;33@>130°C
0.005
25°C' i!30°C
4.8 '3.81
4.8 3.8
0.002 0.45
0.0003 0.04
'Over1x10B| ilx10B
il014
Penta.+HCKO-Chlor
IFLAKES
'62
11.78
i242°C
!278°C
i344°C
(137
250
None to Boiling
0.19 0> 16°
10.489 100°
I Light Yellow
10.05
35@150°C
!0.001;
25°C: il50°C
!4.4 3.7
4.4 .3.7
0.0009 0.99
: 0.0002 , 0.44
Over 1«10B |1x10B
11051
Octa-Chlor
POWDfc'R
i70
1 2.00
i310°C
''
I185
i None to 430
None to BollinQ
1 Light Yellow
,0.1
2141
Blunct
•; CAKES
M
11.G3
'.135
I Grnv White
i 0.05 .
;183@160°C
:0.06@ 140°C
24 1
r25°
13.8
'3.8
! 0.0006
! 0.0002 ,
| Our 1»108
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Reactivity with environmental chemical species and potential
complex formulations have not been studied. However, as discussed below
some insights might be drawn from the chemical similarity of these
compounds to polychlorinated biphenyls (PCBs).
Production Levels and Trends
The production process generally involves the chlorination of
naphthalene in the presence of a ferric and antimony chloride catalyst.
Foreign manufacturers of chlorinated naphthalenes are Bayer in Germany
(Nibren waxes) and the Imperial Chemical Industries Ltd. in the United
Kingdom (Seekay waxes). Crow (1970) has stated that in the United
Kingdom only chlorinated naphthalenes with four chlorines or less are
produced and sold. Personal communications with the International Trade
Commission (formerly the U.S. Tariff Commission) revealed that the last
reported imports of any chlorinated naphthalenes were 53 pounds (24 kg)
of 1-chloronaphthalene in 1963 and 12,231 pounds (5,560 kg) of the same
in 1964. Since that time no imports of chlorinated naphthalenes (by
trade name or chemical name) have been reported.
The only U.S. manufacturer of chlorinated naphthalenes is the
Koppers Company which produces them under the trade name of Halowaxes at
a plant in Bridgeville, Pennsylvania, a few miles from Pittsburgh. In
1956, the total output was about 7 million pounds (about 3.24 million
kilograms) (Hardie, 1964). Hardie (1964) suggested that the decline in
use evident at the time was due to their serious disadvantages, such as
their toxic nature in handling. In 1972 the market for chlorinated
naphthalenes was less than 5 million pounds (2.27 million kilograms)
(Koppers, 1973). Recent indications are that the market has continued
to decline slightly over the last two years (Hoy, 1975).
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Past and Present Use Patterns
Historically, the chlorinated naphthalenes were used in the 1930's
and 40's as electrical cable insulating materials where they serve water
repellant and flame resistant functions. This use led to recognition
of the chlorinated naphthalenes as a serious occupational health problem
during cable manufacture. Use of the penta- and hexachloronaphthalenes
in cable manufacture was discontinued due to occupational health problems
and the introduction of plastics as substitute materials after World War
II (Hardies 1964). Use as electrical insulating material in certain
applications remains today mostly for capacitors where lower chlorinated
members of th£ group, which exhibit a low order of toxicity, are employed.
Uses as lubricant additive associated with feed pelletizing machinery
and wood preservatives, both popular in the 40's and 50's, have been
discontinued largely due to serious cattle poisoning incidents associated
with those uses in the early 1950's.
Table II lists the various commercial mixtures presently marketed
as Halowaxes and indicates the number of chlorines, the approximate
percentage of the market and the current principal commercial uses. The
tri- and tetrachloronaphthalenes (Halowax 1001 and 1099) are solids and
make up more than half of the United States market. .They are used
almost exclusively as the paper impregnant in automobile capacitors.
The second largest part of the market is the mono- and dichloronaphthalenes
(Halowax 1000 and 1031 liquids), most of which are used as an oil additive
to clean sludge and petroleum deposits in engines. These products find
some use in the fabric dyeing industry, specifics about which are
considered trade secrets by producers and users. The manufacturer's
product bulletin indicates that monochloronaphthalene (Halowax 1031) is
about 96% pure, containing predominantly 1-chloronaphthalene, and is
used as a raw material for production of dyes.
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The highly chlorinated naphthalenes (Halowax 1013 and 1014) are
used mainly as electroplating stopoff compounds in relatively small
quantities. Some specialized minor uses as an additive in automobile
and industrial gear oils and cutting oils are also mentioned in the
manufacturers product bulletin (Koppers9 a). The product bulletin also
mentions other possible minor applications of Halowax 1000 as solution
polymerization solvents, gauge fluids, inert liquid seals for instruments,
and photoelastic immersion fluids. Halowax 1001 is said to have applications
in the paper coating and precision casting industries.
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TABLE II
USES OF CHLORINATED NAPHTHALENES
(KOPPERS, 1973)
HALOWAX % OF CHLORINATED % MARKET*
ISOMERS (1972)
1000 60%
1031 95%
1000 60%
1031 95%
1001 ( 10%
1099 (40%
1013 10%
1014 20%
MONO
MONO
MONO
MONO
01
TETRA
TRI
TETRA
40% Dl 15-18%
5% Dl
40% Dl 10%
5% Dl
40% TRI 65-66%
10% PENTA
50% TETRA 40% PENTA 8%
40% PENTA 40% HEXA
USES
ENGINE OIL ADDITIVE
TO DISSOLVE SLUDGE
AND DEPOSITS
PROPRIETARY
USES IN FABRIC
IMPREGNANT FOR AUTO-
MOBILE CAPACITORS
MOSTLY AS ELECTRO-
PLATING STOPOFF
COMPOUNDS, ALSO
IMPREGNANT FOR CARBON
ELECTRODES USED FOR
CHLORINE PRODUCTION
1051
10% HEPTA 90% OCTA
.5%
UNKNOWN
•BASED ON MARKET OF LESS THAN 2.27 x 108a (5 MILLION LBS.)
0
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II. ENVIRONMENTAL EXPOSURE FACTORS
The potential for environmental exposure may be significant when
these compounds are used as oil additives, electroplating stopoff com-
pounds, and in the fabric dyeing industry. With the latter two uses,
effluent discharges from point sources may release these compounds to
the environment, while with the former, more widespread non-point
sources would be involved. The largest use (about two-thirds of the
market) of these compounds is as an impregnant for automobile capacitors.
Automobile capacitors can be considered disposable items since they are
often changed during engine tune-ups. This use is in a temporarily
"closed" system, and the extent to which chlorinated naphthalenes will
leach out or be released has not been determined. Previous use in
products as insulation., e.g., old cables, could allow entry to the
environment as a result of general waste disposal and physical breakdown
of the products.
Chlorinated naphthalenes, like PCBs, exhibit a high degree of
chemical and thermal stability as indicated by their resistance to most
acids and alkalies and resistance to dehydrochlorination (Koppers, a).
Although a number of researchers have recognized the similarity between
the physical and chemical properties and uses of PCBs and chlorinated
naphthalenes (Armour and Burke, 1971; Goerlitz and Law, 1972) and have
developed analytical procedures for low level detection in environmental
samples, only two reports of chlorinated naphthalenes contamination of
the environment in the U.S have been reported. In addition, Koeman ejt
aj_. (1973) detected traces of chlorinated naphthalenes during PCB and
DDE residue analysis in cormorants (fish-eating birds) that were found
dead in various parts of the Netherlands. In most cases the analytical
procedures were developed to assure that chlorinated naphthalenes were
not interfering with analysis for PCBs or organochlorine pesticides such
as DDT. Some of the analytical techniques developed, especially gas
chromatography-mass spectrometry (GC-MS), would allow detection and
quantification of chlorinated naphthalenes in environmental samples.
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The Food and Drug Administration (FDA), in their monitoring
program for pesticides and other industrial chemicals, such as PCBs,
in agricultural products, is able to determine the presence of chlorinated
naphthalenes in food (grain, fruits, vegetables, milk, eggs, cheese, fish,
etc.). This capability has been available since 1970. To date, no findings
have been reported by FDA District Laboratories. This surveillance
program is carried out on a continuing basis and would be in a good
position to determine whether or not chlorinated naphthalenes become a
significant contaminant of agricultural products (FDA, 1975).
Similarly, a personal communication with the EPA National Hater
Quality Laboratory in Duluth, Minnesota revealed that they have been
monitoring samples of fish from the Great Lakes as well as many major
rivers in the U.S. and have found no chlorinated naphthalenes as of
February, 1975. The analytical chemist did indicate that some tentative
findings of chloronaphthalenes had been made which, upon confirmatory
analysis, proved to be other chlorinated hydrocarbons. For example, a
tentative tetrachloronaphthalene identification was later found to be a
compound with the same molecular weight, pentachlorophenol. Another
tentative identification of octachloronaphthalene was later determined
to be a pentachloroterphenyl with nearly the same molecular weight. One
other tentative finding in Great Lakes herring gull extract awaits
confirmation at the California Water Resources Control Board. The type
of analytical procedures involved in identifying chlorinated naphthalenes
seems to make their detection by those doing routine analyses for chlorinated
hydrocarbons unlikely unless chlorinated naphthalenes are specifically
sought.
A study of the distribution of polychlorinated biphenyls in the
aquatic environment by Crump-Wiesner et^ aj_. (1973) led to the first
report of chlorinated naphthalenes in an environmental sample in the
United States. In analyzing sediment samples from a south Florida
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drainage ditch, mixtures of chlorinated naphthalenes ranging from 1.25
to 5 mg/kg were found. Water samples overlying the sediments averaged
5.7 jjg/1. Identification was confirmed by both microcoulometry and GC-
MS. Discussions with the authors revealed that the drainage ditch was
in the vicinity of an airport overhaul hangar.
Law and Goerlitz (1974), in a GC-MS study of chlorinated hydro-
carbons in bottom material from streams tributary to San Francisco Bay,
/kg of chlorinated naphthalenes present in a Guadalupe River
sample. The authors point out that the sample came from an area of no
apparent industrial activity.
Several instances of a disease called bovine hyperkeratosis (Olson,
1969) in the early 1950' s were traced to chlorinated naphthalenes as a
contaminant in pelletized cattle feed. This contamination was due to
the use of a lubricant containing chlorinated naphthalenes in machines
for pelletizing cattle feed. (See Biological Effects - Toxicity below).
Chlorinated naphthalenes have also been detected as a contaminant
in foreign commercial PCB formulations (Phenoclor, Clophen and Kanechlor)
along with chlorinated dibenzofurans. Early investigators did not
detect chlorinated naphthalenes in domestic PCB formulations (Aroclors)
(Vos e_t al., 1970; Roach and Pomerantz, 1974). Chlorinated naphthalenes
are present in domestic PCBs but at lower levels than in foreign formulations,
Bowes e_t aj_. (1975), using a more sensitive analytical technique, identified
by MS three peaks of a chromatogram of Aroclor 1254 as chlorinated
naphthalenes.
Environmental decomposition of chlorinated naphthalenes has received
limited study. Only the monochlorinated naphthalenes have been studied
under biological conditions similar to those found in the environment.
Walker and Wittshire (1955) examined the decomposition of both 1-chloro-
and 1-bromonaphthalene by soil bacteria and found that two species of
bacteria, obtained from soil, would grow in a mineral salts medium with
1-chloronaphthalene as the sole carbon source. The isolation of
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8-chloro-l,2-dihydro-1,2-dihydroxynaphthalene and 3-chlorosalicylic acid
suggests the metabolic route shown in Figure 2. Similar results were
reported for 2-chloronaphthalene by Canonica and coworkers (1957).
Okey and Bogan (1965) examined the rate of metabolism of 1-chloro-
and 2-chloronaphthalene by sewage sludge bacteria that were first grown
on unsubstituted naphthalene. The initial concentration of chlorinated
substrates was 1 mg/1 and the substrate was the only source of carbon.
The following relative rates of metabolism were observed:
naphthalene >» 2-chloronaphthalene» 1-chloronaphthalene.
The microbial degradation of the highly chlorinated naphthalenes
has not been studied. Gibson (1972) has suggested that the initial
reactions in mammalian and microbial systems are quite different as is
depicted in Figure 3. There is little certainty about the environmental
fate of chlorinated naphthalenes. No literature references are available
on the environmental stability and transport of chlorinated naphthalenes
within the biosphere, including bioaccumulation and behavior in ecological
food chains, although at least a potential for bioaccumulation appears
to have been demonstrated since traces have been detected in one species
of fish-eating birds (Koeman et al_., 1973) and in stream sediments
(Crump-Wiesner et al_., 1973; Law and Goerlitz, 1974). Further, an
evaluation of the physical and chemical data on these compounds together
with the available data on mammalian and microbial metabolism and an
intuitive correlation based on the similarities in chemical structure
and physical properties (low water solubility, low volatility) between
PCBs and chlorinated naphthalenes, indicate that the higher chloro-
naphthalenes are relatively stable and are likely to persist when
released to the environment (Howard and Durkin, 1973).
Recent photolysis studies have shown a potential for photodegradation
of polychlorinated naphthalenes in the environment. Experiments
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FIGURE 2
Suggested Route of Decomposition of
1-Chloronaphthalene by Soil Bacteria.
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FIGURE 3
Proposed mechanism of naphthalene dihydrodiol
formation in mammalian and microbial systems.
(From :Gibson, 1972)
Pseudomonas
microsomes
2e-
2H+
epoxide
hydrase
H OH
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various polychlorinated naphthalenes in methanol solution irradiated
at a peak energy output of 300 nm resulted in dechlorination and di-
merization. Sunlight irradiations were carried out on solid films
in quartz vessels and resulted in insoluble polymeric material (Ruzo
et al_., 1975).
Another aspect about which there is little certainty but considerable
concern is the potential epoxidation of the chlorinated naphthalenes to
produce a relatively small stable agent capable of covalent linkage imp!icited
in carcinogenicity of epoxides like dieldrin (Figure 3).
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III. BIOLOGICAL EFFECTS
Metabolic Effects
The primary observed metabolic effect of the chlorinated naphtha-
lenes is to interfere with the metabolism of carotene and its trans-
formation to Vitamin A and is reflected in decreased plasma Vitamin A
(Olson, 1969). The Vitamin A effect is highly variable and subject to
species-specific variation (Hansel and McEntee, 1955). Goats, sheep,
swine, mice, chickens, and rats are much less susceptible than cattle
fOlson, 1969).
In the surveyed literatures male rabbits were the only subjects
used to study the metabolism of chlorinated naphthalenes (Cornish arid
Block, 1958). The compounds studied were 1-chloronaphthalene, di-,
tetra-, penta-, hepta-, and octachloronaphthalene. Naphthalene metabo-
lites and the presence of unchanged compound were tested for in urine
after administration by stomach tube of 1 gram of each test compound.
1-Chloronaphthalene, dichloronaphthalene, and tetrachloronaphthalene
showed patterns of excretion similar to naphthalene. The excretion
products of naphthalene are largely glucuronides with small amounts
converted to mercapturic acid derivatives, sulfates, and phenolic compounds,
The higher chlorinated naphthalenes did not yield an increase in these
urinary metabolites. Less than 20% of the administered dose of penta-
and heptachloronaphthalenes were found to be excreted in urine and
feces.
This study suggested that the toxic symptoms produced in the rabbit
by highly chlorinated naphthalenes can be related to the inability of
the animal to metabolize and excrete these compounds. However, these
compounds may be metabolized by pathways which yield excretory products
not included in this study, or they may be deposited in the tissue,
particularly fat depots, and metabolized or excreted unchanged over long
periods of time (Cornish and Block, 1958).
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Toxicity
Evaluation of the available toxicity information on the chlorinated
naphthalenes indicates that the degree of toxicity, in general, increases
with the degree of chlorination. Under acute conditions of human dermal
exposure"to mono, di, tri, and tetra compounds, slight or no observable
reactions were reported. The higher chlorinated members of this class,
on the other hand, especially the penta and hexa compounds, have been
associated with dermal toxicity (chloracne) and liver damage of some
severity under occupational exposure conditions prior to and during
World War II years. A few fatalities from chloronaphthalene-induced
liver necrosis from occupational exposure have been reported, the last
in 1944. Recent study of occupational chloracne problems associated
with chlorinated naphthalene exposure has shown limited systemic toxicity
and no evidence of liver involvement (Kleinfeld, 1972).
Three natural routes are available for the human intake of chlorinated
naphthalenes: ingestion, inhalation, and cutaneous absorption. Of
these, Crow (1970) concluded, after a critical review of substances
associated with chloracne pathology, that the more important route in
occupational exposure is inhalation. The absence of chloracne in workers
handling cold chloronapthalene solids (Collier, 1943; Crow, 1970) led to
the recognition that the vapors from molten chlorinated naphthalenes are
a critical factor in the toxic responses observed. However, the dermal
absorption route should not be disregarded. Past occupational studies
often failed to characterize adequately the exposure conditions so that
the mode of entry in most situations is best considered as a probable
combination of vapor inhalation and cutaneous absorption. In domestic
animals, ingestion is by far the most common route of exposure and
results in the most severe pathology (Huber and Link, 1962; Olson,
1969).
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Because chlorinated naphthalenes have never enjoyed widespread
household use, occupational rather than accidental or environmental
exposure predominates in the relevant literature on human toxic effects.
Two clinically distinct but often concurrent and possibly physiologically
related syndromes have been described: liver necrosis and chloracne.
(Chloracne is a general term and describes the skin irritation that can
be produced not only by chlorinated naphthalenes but also by other
chlorinated compounds including commercial grade biphenyls, a few specific
benzenes, phenols, and dibenzofurans. Chloracne accompanied by itching,
however, may be specific to the chlorinated naphthalenes.)
Any attempt to label these syndromes as acute or chronic is potentially
misleading. Exposures of three to four months are often noted in the
clinical literature (e.g., Schwartz and Peck, 1943; Collier, 1943:,
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