EPA-660/3-74-025
DECEMBER 1974
Ecological Research Series
The Fate of Select Pesticides in the
Aquatic Environment
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Corvallis, Oregon 97330
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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
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1. Envi ronmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH STUDIES
series. This series describes research on the effects of pollution
on humans, plant and animal species, and materials. Problems
are assessed for their long- and short-term influences. Investigations
include formation, transport, and pathway studies to determine
the fate of pollutants and their effects. This work provides
the technical basis for setting standards to minimize undesirable
changes in living organisms in the aquatic, terrestrial and atmospheric
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policies of the Environmental Protection Agency, nor does mention
of trade names or commercial products constitute endorsement or
recommendation for use.
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OPTS-TECHNICAL INFORMATION CENTER
EPA-660/3-74-025
December 1974
THE FATE OF SELECT PESTICIDES IN THE
AQUATIC ENVIRONMENT
by
James R. Sanborn
Project R-800736
Program Element 1BA023
ROAP 21 AIM, Task 02
Project Officer
Mrs. Doris F. Paris
Southeast Environmental Research Laboratory
National Environmental Research Center
Athens, Georgia 30601
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington. D.C. 20402 - Stock No. 5501-0099S
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ABSTRACT
In this study 17 organic pesticides and five industrial chemicals were
examined in a terrestrial-aquatic model ecosystem in an effort to
determine their persistence and accumulation by the organisms of this
system. Several classes of pesticides are represented as one or more
insecticides, herbicides, miticides or plasticizers were investigated
in this system. The use of this system for examining uptake and per-
sistence of widely used agricultural chemicals provides the necessary
data for comparison of field data to provide a framework which can be
used to assess the potential environmental impact of new pesticides
before they are given a recommendation for generalized use.
The data obtained from this work suggest that this model ecosystem is
useful for the determination of the uptake and persistence of pesti-
cides by the organisms. In general, it was found that most chemicals,
with the exception of the persistent soil insecticide, dieldrin, under-
went extensive degradation under the experimental conditions of the
system. Dieldrin was exceptional in its behavior in that > 96% of the
radioactivity isolated from the organisms was unchanged dieldrin,
clearly indicating the extreme inertness of this chlorinated hydrocarbon
to undergo biological or chemical modification.
This report was submitted in fulfillment of Project R-800736 by the
Illinois Natural History Survey and Board of Trustees, University of
Illinois, under the sponsorship of the Environmental Protection Agency.
Work was completed as of June 30, 1973.
ii
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CONTENTS
Abstract
List of Tables
Acknowledgements
Section
Conclusion
Introduction
Examination of Select Insecticides
Examination of Select Herbicides
I
II
III
IV
V
VI
VII
VIII
Examination" of a Miticide, Select Plasticizers,
a Fungicide and a Bacteriostat
References
Publications
Chemical Nomenclature for Compounds Examined
in a Model Ecosystem
Page
11
iv
vii
1
2
3
30
56
76
80
82
iii
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TABLES
Number Page
Concentrations (ppm) of Bux^ and metabolites
in organisms in a model ecosystem 4
2 Concentrations (ppm) of Bux^ and metabolites
in water of a model ecosystem 5
14
3 Concentrations (ppm) of ring-labelled C
carbaryl and metabolites in organisms and water
of a model ecosystem 7
4 Concentrations (ppm) of ring-labeled carbofuran
and metabolites in organisms of a model ecosystem 10
5 Concentrations (ppm) of ring-labeled carbofuran
and metabolites in water of a model ecosystem 12
6 Concentrations (ppm) of carbonyl-labeled carbofuran
and metabolites in organisms of a model ecosystem 13
7 Concentrations (ppm) of carbonyl-labeled carbofuran
and metabolites in water of a model ecosystem 15
8 Concentrations (ppm) of dieldrin and metabolites
in organisms of a model ecosystem 17
9 Concentrations (ppm) of dieldrin and metabolites
in water of a model ecosystem 18
10 Concentrations (ppm) of lindane and Aroclor 5460^
and metabolites in organisms in a model ecosystem 21
11 Concentrations (ppm) of lindane and Aroclor 5460^
and metabolites in water in a model ecosystem 22
12 Concentrations (ppm) of Orthene0^ and metabolites
in organisms in a model ecosystem 25
13 Concentrations (ppm) of Orthene-^ and metabolites
in water in a model ecosystem 26
14 Concentrations (ppm) of parathion and metabolites
in organisms of a model ecosystem 28
15 Concentrations (ppm) of parathion and metabolites
in water of a model ecosystem 29
16 Concentrations (ppm) of alachlor and metabolites
in organisms in a model ecosystem 31
IV
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Number Page
17 Concentrations (ppm) of alachlor and metabolites
in water in a model ecosystem 32
18 Concentrations (ppm) of propachlor and metabolites
in organisms in a model ecosystem 33
19 Concentrations (ppm) of propachlor and metabolites
in water in a model ecosystem 34
20 Concentrations (ppm) of Bladex^ and metabolites
in organisms in a model ecosystem 36
21 Concentrations (ppm) of Bladesc^ and metabolites
in water in a model ecosystem 37
22 Concentrations (ppm) of Bentazorr-^ and metabolites
in organisms in a model ecosystem 39
23 Concentrations (ppm) of Bentazorr-^ and metabolites
in water in a model ecosystem 40
24 Concentrations (ppm) of dicamba and metabolites in
organisms in a model ecosystem 42
25 Concentrations (ppm) of dicamba and metabolites in
water in a model ecosystem 43
26 Concentrations (ppm) of 2,4-D and metabolites in
organisms in a model ecosystem 45
27 Concentrations (ppm) of 2,4-D and metabolites in
water in a model ecosystem 46
28 Concentrations (ppm) of pyrazon and metabolites
in organisms in a model ecosystem 48
29 Concentrations (ppm) of pyrazon and metabolites
in water in a model ecosystem 49
30 Concentrations (ppm) of Trifluralirt-^1 and
metabolites in organisms in a model ecosystem
after sorghum treatment 51
31 Concentrations (ppm) of Trif luraliir^ and
metabolites in water in a model ecosystem
after sorghum treatment 53
32 Concentrations (ppm) of Trifluralirf^ and
metabolites in organisms in a model ecosystem
after sand treatment 54
33 Concentrations (ppm) of Trifluralirt^' and
metabolites iu water in a model ecosystem
after sand treatment 55
v
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Number Page
34 Concentrations (ppm) of Banomite^ and metabolites
in organisms in a model ecosystem 58
35 Concentrations (ppm) of Banomite*^and metabolites
in water in a model ecosystem 59
36 Concentrations (ppm) of di-n-octyl phthalate and
metabolites in organisms of a model ecosystem 61
37 Concentrations (ppm) of di-ri-octyl phthalate and
metabolites in organisms of a model ecosystem 62
38 Distribution of chlorinated biphenyls and their
degradation products in the model ecosystem 64
39 Concentrations (ppm) of Captan and metabolites
in organisms in a model ecosystem 68
40 Concentrations (ppm) of Captan and metabolites
in water in a model ecosystem 70
41 Concentrations (ppm) of hexachlorophene and
metabolites in organisms in a model ecosystem 73
42 Concentrations (ppm) of hexachlorophene and
metabolites in water in a model ecosystem 74
43 Accumulation factors for fish and snail for
compounds examined in the model ecosystem 75
vi
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ACKNOWLEDGEMENTS
The author would like to acknowledge several persons during this
investigation. The initial studies were directed by Dr. G. M. Booth
and carried out by Drs. Ching-Chieh Yu and Dale J. Hansen. Also, an
acknowledgment is in order for Dr. William F. Childers and Mr. Lowell
Davis who reared the aquatic organisms and provided useful information
regarding the proper procedures for the maintenance of these organisms.
Valuable discussions with Professor Robert L. Metcalf, the developer
of this system, provided important insights regarding the interpreta-
tion of segments of the data in this report. In addition, the skillful
assistance of M. Kathryn McClendon who helped finish the latter stages
of this work as well as provided assistance during the preparation of
this report is acknowledged. Finally, the outstanding laboratory
facilities of the Illinois Natural History Survey and the University
of Illinois are gratefully acknowledged.
vii
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SECTION I
CONCLUSION
The data presented in this report demonstrate the usefulness of a
terrestrial-aquatic model ecosystem for the prediction of the persist-
ence and uptake of selected organic chemicals. Only the soil
insecticide, dieldrin, and the herbicide, TrifluralinB/, were found to
accumulate over the concentration in the water in the fish and snail.
The experiment with lindane and the extender, AroclouB) 5460, yielded
information that indicated the snail accumulation was unaffected as
compared to lindane examined alone in this system, while the fish
accumulation was increased slightly. Other chemicals examined in this
system were three pure ^C labeled polychlorinated biphenyls which
accumulated in increasing amounts in the fish and snail as the number
of chlorine substituents was increased. In addition, investigation of
the fate of the phthalate plasticizer, di-ri-octyl phthalate (DOP) ,
demonstrated substantial accumulation in the fish and snail. Neither
the bacteriostat, hexachlorophene, the fungicide, captan, nor the
miticide, BanomiteS', accumulated to significant amounts in the fish
or snail.
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SECTION II
INTRODUCTION
The utilization of a model ecosystem to examine the persistence and
uptake of pesticides, or any other organic or inorganic chemical, has
been shown recently to be a valid method for predicting the behavior of
these materials in a terrestrial-aquatic environment (Metcalf et al.,
1971; Metcalf et_ al., 1973). Though it has been adequately described
before, a brief description of the terrestrial-aquatic model ecosystem
will be useful for interpreting the contents of this report.
The system is housed in a glass aquaria (25 x 30 x 45 cm) and contains
a sand-water interface consisting of 15 kg of sterilized white quartz
sand and 7 liters of standard reference water (Freeman, 1953). Sorghum
(Sorghum halpense) is grown in the sand to a height of 10-12 cm which
is then treated on the leaves with 5 mg of a radlolabeled pesticide
dissolved in acetone. Each compound was run in duplicate through the
model ecosystem. The design of this system and treatment level corres-
pond to a farm pond surrounded by a watershed under cultivation that
has been treated 1 Ib/acre (VL.12 kg/hectare). After the sorghum has
been treated, saltmarsh caterpillar larvae (Estigmene acrea) are added
to eat the treated plant and therefore simulate both the first member
of a food chain as well as act as an effective distributing agent for
the labeled pesticide inside the system. The water contains several
members of a fresh water aquatic food chain: namely, snails (Physa sp.),
water fleas (Daphnia magna) and green filamentous algae (Oedogonium
cardiacum).
After 27 days mosquito larvae are added to the system to become another
member of the food chain and 3 days later a mosquito fish (Gambusia
affinis) is added to become the final segment of the system. At the
end of 33 days the entire system is taken apart and the organisms and
water are analyzed for radioactivity by extraction with organic solvents
and quantitation is carried out by counting the extracts by liquid
scintillation techniques. In addition, the extracts are spotted on
thin-layer chromatographic plates, developed with appropriate solvents
and exposed to X-ray film to locate and identify the chemical composi-
tion of the solvent extracts. Identification of metabolites is made by
co-chromatography with proposed metabolites as well as techniques of
infrared, nuclear magnetic resonance and mass spectrometry. Once the
identity of the metabolites or degradation products is known, then
quantitative determination can be made on the propensity of an organic
chemical or its metabolites to be concentrated from the water by the
organisms of the system.
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SECTION III
EXAMINATION OF SELECT INSECTICIDES
The first segment of this report is concerned with the behavior of
select insecticides in the model ecosystem. Initially, the system was
operated with several additional organisms besides the standard fish,
snail, mosquito, Daphnia and algae; but later it was decided to delete
these additional organisms so that more valid comparisons could be made
with data derived by other investigators using the system developed by
R. L. Metcalf and co-workers.
The first insecticide examined is the carbamate insecticide, BuxB),
which is a 3:1 mixture of m-(l-ethylpropyl)phenyl fj-methylcarbamate and
m-(l-methylbutyl)phenyl IJ-methylcarbamate . This insecticide has shown
promise as a soil insecticide for control of pests under corn. It is
moderately toxic to warm-blooded animals as it has acute oral and
chronic U^Q'S of 87 and 400 mg/kg to the rat. The metabolism of
m-(l-methylbutyl)phenyl N -methyl carbamate has been examined in rats and
the primary excretion products found in the urine are conjugates of the
phenol, m-(l-methylbutyl)phenyl tl-hydroxymethyl methylcarbamate and
m-(l-methyl-l-hydroxybutyl)phenyl N^methylcarbamate (Sutherland et al. ,
1970). Further, application of Bux® to the soil in which maize was
grown resulted in no carbamate residues in the plants and primary
metabolites isolated from the soil were the result of hydrolysis of the
carbamate to the phenol and oxidation of Bux-S' to m-(l-methyl-l-
hydroxybutyl)phenvl N-methylcarbamate. From these studies it was cal-
culated that BuxB'had a soil half-life between 1-3 weeks (Knaak, 1971).
Examination of the data in Tables 1 and 2 suggest that Bux3y is a non-
persistent insecticide as none of the snails, mosquitoes or fish
contain residues of the intact insecticide. Further, the extractable
radioactivity from these organisms averaged 18% and was in such small
quantities that the metabolites were uncharacterizable. The only animal
that contained Bussx was the crab (Uca mane lens is) which had 0.0498 ppm
and several other unidentified spots on the chromatogram. While the
crab contained Bux-B/ , nevertheless the extractable radioactivity only
accounted for about 15% of the total radioactivity in the organism.
In contrast to the animals of this system, both the algae with 0.980 ppm
and E lode a with 0.245 ppm contained considerable amounts of Bux®.
While these two organisms contained substantial amounts of the parent
compound, the unextractable radioactivity remained high as 81% and 73%
in algae and Elodea, respectively, were acetone insoluble materials.
The water portion of the ecosystem contained small amounts of Bux® with
a value of 0.0000953 ppm for the combined total of unhydrolyzed and
hydrolyzed water. In addition to the Bux® there were several unidenti-
i f ied metabolites in the water. The unextractable radioactivity for the
unhydrolyzed -and hydrolyzed water was slightly higher at 94%.
-------
Table 1
Concentrations (ppm) of Bux&) and metabolites in organisms
in a model ecosystem
Compound
!£/
II
III
IV
Extractable 1
Unextractable
Grand Total 14C
R//
Algae
0.98 0.980
0.95-0.62 0.474
0.62-0.28 0.252
0.28-0.02 0.074
0.00 0.00111
1.783
7.825
9.608
Clamfe/
--
--
--
--
--
0.0206
0.0826
0.103
Crab
0.0498
0.168
0.056
0.0079
0.00508
0.287
1.59
1.877
Daphnia
--
--
--
--
--
0.128
1.42
1.548
Elodea
0.245
0.107
0.206
0.119
0.268
0.945
2.51
3.455
Fish
--
--
--
--
--
0.0449
0.230
0.275
Mosquito
--
--
--
--
--
0.178
0.602
0.780
0.119
0.662
0.781
Microfiber absorbent sheets impregnated with silica gel, acetone-n-hexane,15:85 by volume
—' Clam died 7 days after application of Bux^ to system
—I Roman numerals - unknown spots
-------
Compound
Table 2
Concentrations (ppm) of Bux® and metabolites
in water of a model ecosystem
a/
Unhydrolyzed Water
Hydrolyzed Water
Bux® 0.98
b/
I-' 0.95-0.62
II 0.62-0.28
III 0.28-0.02
IV 0 . 00
Extractable ^C
Unextractable ^C
Grand Total 14C
0.0000908
0.0000454
0.00000258
--
0.000000090
0.00014
0.00281
0.00295
0.00000459
0.0000360
0.0000126
0.0000589
0.000103
0.000215
0.00288
0.00311
a/
— Microfiber absorbent sheets impregnated with silica gel, solvent:
atetone-n-hexane, 15:85 by volume
_' Roman numerals - unknown spots
-------
In summary, it can be concluded from the data obtained from the
examination of Bux© in the model ecosystem that this carbamate insecti-
cide does not accumulate in any of the animals of the system, though it
appears to be concentrated from the water by the algae and Elodea.
10,283x and 2,571x, respectively. This phenomenon is peculiar in that
this substantial accumulation does not appear to cause any damage to
these plants. The probable explanation for the absence of BuxS' in
either the fish or mosquito relates to the water instability of this
material. The program of operation of this system places these two
organisms in the system on the 27th day for the mosquito and the 30th
day for the fish, and by this time the Bux® has undergone hydrolysis
to the phenol.
Sevii®, or carbaryl, was the first commercial carbamate insecticide to
find widespread use in the early 1950's. Consequently, because of its
extensive use, the metabolism of this insecticide has been thoroughly
examined by numerous investigators and an adequate review of the
metabolism and degradation of Sevin® has been outlined (Fukuto and Sims,
1971). Briefly, the primary routes of metabolism are ring hydroxylation,
hydrolysis to yield QJ-napthol and transformation of the N-
methylcarbamoyl group to the N-hydroxymethyl group.
Examination of the data in Table 3 gjLyes clear evidence that this car-
bamate insecticide is similar to Buses' in its metabolic and degradative
behavior in this system. While all of the organisms contained substan-
tial radioactivity, none of the organisms contained carbaryl. The
quantity of unextractable radioactivity in the organisms was on the
average about 78%, which was slightly lower than that obtained for BuxSl
The aqueous segment of the ecosystem did not contain any carbaryl, but
two identifiable metabolites in ppt concentrations were found; namely,
N-hydroxymethyl carbaryl at 88 ppt and 7-OH carbaryl at 99 ppt. Other
metabolites were co-chromatographed with the extract from water, but
the radioactive spots did not correspond with any of the known com-
pounds. Again, as in the case of Bu*D, substantial amounts of
unextractable radioactivity (72%) were found in the water. The greater
susceptibility of carbaryl to undergo degradation to the numerous
degradation products isolated from the water perhaps can be ascribed to
the lower aromatic character of the napthalene ring which allows facile
hydroxylation to polar, water soluble metabolites.
Carbofuran
The last carbamate investigated in the present study is carbofuran, an
outstanding soil insecticide used for control of insects which affect
corn. It was of particular importance to examine this insecticide in
relation to the state of Illinois as nearly 40% of the corn in 1972 was
treated with either an organic phosphate or carbamate (Kuhlman and
Cooley, 1973). Further, since aldrin, heptachlor and chlordane were
not recommended for use in Illinois to control insects which are pests
-------
Table 3
Concentrations (ppm) of ring-labelled -"-^C carbaryl and metabolites
in organisms and water of a model ecosystem
/
Clam Crab Daphnia Elodea Mosquito Fish
0.118 — 0.057
Compound
I
II
carbaryl
III
A
IV
V
VI
B
C
D
VII
E
VIII
• Rf
0.95
0.87
0.85
0.83
0.79
0.67
0.53
0.47
0.35
0.30
0.26
0.22
0.18
0.12
Water
--
0.000161
--
0.000155
--
0.000221
0.00006
0.000133
0.000081
--
--
0.000018
0.000099
0.000765
Algae
0.175
--
--
--
--
--
--
--
--
--
--
—
--
__
Snail
0.03
0.0098
0.085
0.86
-------
Table 3 (con't.)
oo
Compound
IX
X
Extractable ^C
Unextractable 14C
Grand Total ^C
R a/
0.08
0.00
Water
0.00151
0.00748
0.0107
0.0267
0.0374
Algae Clam
0.614
0.789
3.964
4.753
0.286
1.341
1.627
Crab Daphnia Elodea Mosquito Fish Snail
0.0137 -- 0.039
0.257 -- 0.909 -- 0.091 0.45
0.398 0.295 1.089 0.360 0.091 1.34
0.738 2.385 3.511 2.657 0.337 3.79
1.136 2.681 4.600 3.017 0.428 5.13
£ Silica Gel GF-254, chloroform-methanol, 49:1 by volume
—' Roman numerals - unknown spots
A 1-napthol
B N-hydroxymethyl carbaryl
C 5-hydroxy carbaryl
D 4-hydroxy carbaryl
E 7-hydroxy carbaryl
-------
of corn (Kuhlman, 1973), it is clear that substitutes must be found,
such as carbofuran. It was therefore paramount that this insecticide
be examined in terms of its persistence and uptake by the organisms of
this model ecosystem. An additional factor, which made it essential
that this insecticide be examined, is its extreme toxicity to warm-
blooded animals as it has an oral LD5Q for the rat of 4 mg/kg (Metcalf,
1971).
Substantial work has been carried out on the metabolism of carbofuran
and it has been adequately reviewed (Fukuto and Sims, 1971). The basic
scheme of metabolism in plants and animals is oxidation of the 3-carbon
to yield 3-hydroxy and 3-ketocarbofuran. Additional sites of metabolism
involve aromatic hydroxylation and modification of the N-methylcarbamoyl
moiety to give N-hydroxymethyl carbofuran. Environmental studies in
soil have shown that carbofuran is hydrolyzed to yield the phenol,
2,3-dihydro-7-hydroxy-2,2-dimethylbenzofuran. The half-life for the
transformation of the carbamate to the phenol was determined to be
about 30 days. After the transformation of carbofuran to the phenol,
the phenol becomes an unextractable residue with a half-life for
extractability of about 7 days (Knaak, 1971).
Examination of the data in Tables 4 and 6 for carbofuran and its degra-
dation products reveals that none of the organisms contained residues
of carbofuran. In the carbonyl labeled carbofuran there were several
unknown compounds isolated from Elodea as well as 3-ketocarbofuran
(0.035 ppm), tl-hydroxymethyl carbofuran (0.035 ppm) and 3-
hydroxycarbofuran (0.0118 ppm). While there were not as many
metabolites isolated from the ring-labeled carbofuran, Elodea contained
small amounts of carbofuran phenol, 3-hydroxycarbofuran as well as a
small amount of an unknown material which had an Rf of 0.36. Again,
as previously observed for BuxB) and Sevir®, most of the radioactivity
for carbofuran was unextractable by acetone as values for ring- and
carbonyl-labeled carbofuran were 69% and 77%, respectively. These high
figures appear to be characteristic of carbamates in general and
indicate their susceptibility to undergo degradation or metabolism to
polar, uncharacterizable, unextractable species.
In the water portion of the carbonyl-labeled carbofuran ecosystem
(Table 7) small amounts (0.000538 ppm) of the unchanged insecticide were
isolated from the system. In comparison in the ring-labeled system
(Table 5) the tic resolution was not as precise because carbofuran and
3-ketocarbofuran phenol overlapped. However, there cannot be more than
0.00128 ppm of carbofuran, if it is assumed that the entire spot is
carbofuran. Other spots found in identifiable quantities were 3-
ketocarbofuran, N-hydroxymethyl carbofuran, carbofuran phenol and
3-hydroxy carbofuran. None of these compounds was found in excess of
10 ppt which indicates conclusively that carbofuran degrades to polar,
water soluble materials which do not persist in the water segment of
the ecosystem or remain at high levels.
-------
Table 4
Concentrations (ppm) of ring-labeled carbofuran and metabolites
in organisms of a model ecosystem
Compound
iV
A
B and carbofuran
C
D
E
F
II
III
IV
V
VI
Extractable ^C
Unextr actable ^C
Grand Total ^C
Rf-'
0.98
0.83
0.76
0.70
0.60
0.53
0.46
0.36
0.28
0.13
0.06
0.00
Algae Clam Daphnia Elodea Fish Frog
0.0462 0.197
0.0130 -- -- 0.000304
_-
--
-_
--
0.00526
0.000828
0.191
--
--
0.883 -- -- 0.0216 0.305
0.815 1.087 1.089 2.697 0.0725 0.502
4.648 0.368 4.690 2.993 0.413 1.034
5.463 1.455 5.779 5.689 0.485 1.536
Mosquito Snail
0.418 0.567
0.377
__
-_
__
--
-_
-_
-_
._
._
0.552 0.890
1.071 1.645
4.835 6.270
5.906 7.915
-------
Table 4 (con't.)
—' Microfiber absorbent sheets impregnated with silica gel, solvent system: acetone-n-hexane,
15:85 by volume
b_' Roman numerals - unknown spots
A Carbofuran phenol
B Carbofuran and 3-ketocarbofuran phenol
C 3-ketocarbofuran
D 3-hydroxy carbofuran phenol
E N-hydroxymethyl carbofuran
F 3-hydroxy carbofuran
-------
Table 5
Concentrations (ppm) of ring-labeled carbofuran and metabolites
in water of a model ecosystem
Compound
Unhydrolyzed Water
Hydrolyzed Water
B and carbofuran
C
D
E
F
II
III
IV
V
VI
14
Extractable C
Unextractable
14,
14
Grand Total C
0.98
0.83
0.76
0.70
0.60
0.53
0.46
0.36
0.28
0.13
0.06
0.00
0.000267
0.00884
0.000909
0.000136
0.0000758
0.000121
0.000196
0.000537
0.000537
0.000137
0.000230
0.000493
0.0037
0.111
0.115
0.000762
0.00287
0.000375
0.000423
0.000280
0.000242
0.000415
0.00255
0.00143
0.00259
0.00308
0.0166
0.0316
0.0652
0.097
£/ Microfiber absorbent sheets impregnated with silica gel, solvent
system: acetone-n-hexane, 15:85 by volume
b_/ Roman numerals - unknown spots
A Carbofuran phenol
B Carbofuran and 3-ketocarbofuran phenol
C 3-ketocarbofuran
D 3-hydroxy carbofuran phenol
E N-hydroxymethyl carbofuran
F 3-hydroxy carbofuran
12
-------
Table 6
Compound
Concentrations (ppm) of carbonyl -labeled carbofuran and metabolites
in organisms of a model ecosystem
Algae
Clam
Crab Daphnia Elodea Fish Mosquito Snail
!>/
II
III
carbofuran
A
B
IV
C
V
VI
Extractable ^C
Unextractable 14-C
Grand Total 14C
0.96
0.86
0.75-0.71
0.73
0.63
0.55
0.51
0.48
0.26-0.00
0.00
0.121
—
__
__
0.064
-_
__
0.038
--
0.0482
0.963 0.02065 0.271
3.000 0.100 0.254
3.963 0.12065 0.525
0.0492
0.1261
0.0309
--
0.0350
0.0364
0.0059
0.0118
0.5025
0.342
0.191 1.145 0.0583
1.092 4.835 0.278
1.283 5.980 0.3363
0.221 0.648
__
__
__
__
__
--
__
--
0.088 0.325
0.435 0.972
1.198 6.518
1.583 7.490
-------
Table 6 (con't.)
£/ Microfiber absorbent sheets Impregnated with silica gel, solvent: acetone-n-hexane, 15:85 by
volume
_' Roman numerals - unknown spots
A 3-ketocarbofuran
B N-hydroxymethyl carbofuran
C 3-hydroxy carbofuran
-------
Table 7
Concentrations (ppm) of carbonyl-labeled carbofuran and
metabolites in water of a model ecosystem
Compound
Unhydrolyzed Water
Hydrolyzed Water
i/
II
III
carbofuran
A
B
IV
C
V
VI
Extractable l^C
Unextractable 14
Grand Total ^C
0.96
0.86
0.75-0.71
0.73
0.63
0.55
0.51
0.48
0.26-0.00
0.00
C
0.00000491
0.0000136
--
0.000364
0.00000859
0.00000747
--
0.00000128
0.00000464
0.0000103
0.000415
0.00374
0.00416
0.0000070
0.000110
--
0.000174
0.000650
0.0000246
--
0.0000246
0.000073
0.000756
0.00178
0.00259
0.00437
—' Microfiber absorbent sheets impregnated with silica gel, solvent:
acetone-n-hexane, 15:85 by volume
—' Roman numerals - unknown spots
A 3-ketocarbofuran
B N-hydroxymethyl carbofuran
C 3-hydroxy carbofuran
15
-------
At this point it may be suitable to make some general comments about
the previous three compounds and their behavior in this terrestrial-
aquatic model ecosystem. All three were carbamate insecticides and
were shown to be nonpersistent and did not accumulate in any of the
organisms of this system. This property may be characteristic of all
aryl carbamate insecticides as they have sites for oxidative metabolism,
namely, the ring, the IJ-methyl group and aliphatic side chains. In
addition to these sites, which are susceptible to oxidative metabolism,
the carbamoyl group can undergo hydrolysis to a phenol which detoxifies
the carbamate and provides a moiety which can be conjugated with sugars ,
phosphate or sulfate. If the data obtained for these carbamates in
this model ecosystem is representative of the behavior of aryl N-methyl
carbamate insecticides, then it would appear that the use of these
insecticides will not present ecological problems related to persist-
ence and food chain accumulation.
Dieldrin
The next pesticide to be discussed is the chlorinated hydrocarbon,
dieldrin. The unoxidized precursor to dieldrin, aldrin, was introduced
about 20 years ago as an effective insecticide for the control of soil
insects, particularly those associated with corn. The continual use of
this material for over 20 years has resulted in resistance to this
insecticide and, therefore, the aldrin/dieldrin treatment of corn
insects is not particularly effective for some corn pests (Sechriest
and Sherrod, 1973). The increased emphasis on environmental quality
has also suggested the discontinued use of aldrin and/or dieldrin as
dieldrin, the oxidation product of aldrin, is very persistent with a
soil half-life of about 3 years (Wingo, 1968; Hurtig, 1972). The
persistence is related to the extreme inertness toward chemical or
biological modification. For example, metabolism studies with dieldrin
and wheat (Saha, 1970) indicated that less than 37, of the application
of dieldrin was transformed into metabolites. This corroborates
earlier work done with corn, alfalfa and orchard grass that dieldrin
does not undergo substantial transformation by these plants (Wheeler
e^al. , 1967).
The inert nature of dieldrin to undergo degradation in plants is con-
trasted by metabolic susceptibility when administered orally to a
variety of mammals. For example, 70% of the oral dose to rats is
eliminated, principally via the feces which points to biliary excretion
(Heath and Vandekar, 1964). More recently, the structure of the
principal metabolite from an oral dose to rats has been identified as
6,7-trans-dihydroxydihydro aldrin with a specific rotation of
° + 13.7°.
The data in Tables 8 and 9 for dieldrin in the model ecosystem demon-
strate the inert nature of dieldrin to undergo biological or chemical
degradation. There was dieldrin in every organism in the ecosystem
ranging from a low of 0.495 ppm in the crab (Uca man i lens is) to 230 ppm
in the snail. Even more important is that dieldrin constituted nearly
16
-------
Table 8
Concentrations (ppm) of dieldrin and metabolites
in organisms of a model ecosystem
Compound
I*>
dieldrin
II
A
B
VII
Extractable C
Unextractable ^C
Grand Total 14C
R
0
0
0
0
0
0
f*
.65
.58
.43
.38
.31
.00
Algae
--
14.96
--
0.20
--
--
15.16
1.23
16.39
Clam
--
2.03
--
--
--
--
2.03
0.028
2.06
Crab
--
0.495
--
--
0.043
--
0.536
0.177
0.715
Daphnia
--
5.07
--
--
--
0.07
5.14
0.10
5.24
Elodea Mosquito
0
2
0
2
0
2
.23
.56
__
__
__
.03
.82 1.35
.14 0.25
.96 1.60
Fish
-
12
-
0
0
0
12
0
13
-
.29
-
.19
.07
.03
.57
.65
.22
Snail
0.866
229.87
0.456
1.11
--
0.044
232.3
1.78
234.1
$. Silica Gel GF-254, ether-n-hexane, 3:2 by volume
—' Roman numerals - unknown spots
A 9-hydroxy dieldrin
B 9-keto dieldrin
-------
Table 9
Concentrations (ppm) of dieldrin and metabolites
in water of a model ecosystem
Compound
dieldrin
A
B
m^
IV
V
VI
VII
Extractable
14.
Unextractable
14.
Grand Total
14,
Rf~
0.58
0.38
0.31
0.18
0,12
0.07
0.04
0.00
Unhydrolyzed Water
0.0020
0.00046
0.00040
0.00034
0.00013
0.00012
0.00093
0.00023
0.0046
0.0028
0.0074
Hydro ly zed Water
--
—
—
--
0.00012
0.00023
0.00108
0.00134
0.0028
--
_ H
a/ Silica Gel GF-254, ether-n-hexane, 3:2 by volume
b_/ Roman numerals - unknown spots
A 9-hydroxy dieldrin
B 9-keto dieldrin
18
-------
887o of the total radioactivity isolated from the organisms. This
figure includes both extractable and unextractable radioactivity.
Clearly, dieldrin is not metabolized to polar, water soluble molecules
by the organisms of the system, nor is it degraded by physical or
chemical processes as little of the radioactivity isolated from the
organisms (^9%) is unextractable. This figure contrasts significantly
with that observed for the three carbamate insecticides (o<65-75%) or
the phosphates (^60-70%) which will be reviewed next. In view of the
low, mixed-function oxidase levels of Gambusia affinis (Krieger and Lee,
1972) and Physa (Metcalf ejt al., 1971), it is not surprising that
dieldrin is accumulated by these organisms as they appear to be inca-
pable of transforming the lipid soluble molecule, dieldrin, into water
soluble metabolites.
The distribution of degradation products of dieldrin in the water
(Table 9) differs slightly from the distribution in the organisms as
dieldrin constitutes only 25-28% of the extractable radioactivity.
Furthermore, dieldrin is in lower concentration (0.0020 ppm) than was
isolated from the organisms. The reduced amount of dieldrin in the
water, as compared with organisms, is probably related to the low water
solubility, 0.25 ppm (Gunther et_ al., 1968). If the amount of dieldrin
isolated from the water is divided into the various concentrations of
dieldrin observed in the organisms, then the tendency for dieldrin to
accumulate in the various organisms can be calculated. The concentra-
tion factors for the snail, algae and fish are approximately 115,000,
7,500 and 6,100, respectively. These values compare satisfactorily
with those obtained in the same ecosystem experiment with dieldrin
where the factors were determined to be 61,657 and 2,700 for snail and
fish, respectively (Metcalf et al., 1973). More importantly, the order
of magnitude for accumulation of dieldrin by aquatic organisms has been
observed to be in the same order of magnitude, particularly the fish of
the model ecosystem, as that in fish collected from farm ponds in
Illinois. For example, it has been observed that dieldrin is concen-
trated by several species of fish from 5,000x to 25,000x the
concentration in the water (Childers and Bruce, 1973). This would again
appear to validate the usefulness of the model ecosystem to predict the
behavior of pesticides in the aquatic environment.
Lindane and Aroclor 5460® (i:5 w/w)
The types and variations of experiments that can be carried out in this
terrestrial-aquatic ecosystem are only limited by the imagination of
the investigator. In the experiment with lindane and this polychlorin-
ated terphenyl, the intended purpose was to examine the effect that this
adjuvant might have on the persistence and fate of lindane in the model
ecosystem. This type of experiment is not without precedence as it has
been previously reported that persistence and insecticidal residues of
lindane could be improved by the addition of Aroclor 5460® (Horstein
£t al., 1953; Lichtenstein, 1969). It was concluded that residues of
lindane and Aroclor 5460ty were more persistent because of the retarda-
tion of the evaporation rate of lindane from treated surfaces
v
19
-------
(Tsao, 1953). Further, impetus for conducting this type of paired
interaction experiment is given by the dearth of information under
controlled environmental conditions of studies involving interactions
of chemicals and the effects that an adjuvant, such as Aroclor 5460^4
may have on the environmental persistence of a pesticide.
The fate of lindane alone in this model ecosystem has been investigated
which makes it possible to compare the effect of this plasticizer on
the persistence of lindane (Metcalf et_ al. , 1973). Further, the metabo-
lism of lindane in plants and animals has been adequately reviewed
(Fukuto and Sims, 1971). The initial transformation which results in
inactivation of lindane is a dehydrohalogenation to yield pentachloro-
cyclohexene. This unsaturated chlorinated cyclohexene undergoes further
transformations to form conjugates with glutathione and dechlorination
to form several isomeric chlorinated phenols.
Examination of the data in Table 10 for the distribution of lindane in
the organisms of the model ecosystem shows that lindane is present in
all organisms ranging from about 2.20 ppm for Daphnia to about 26.40 ppm
for the fish. The value for the fish is about 26x greater than the
value found by Metcalf et al. (1973), which would indicate that the
addition of the terphenyl increases the uptake of lindane by the fish.
However, the variability in concentrations of lindane in the two fish
from the duplicate experiments was unusually high, 48.98 ppm and
3.78 ppm, and therefore, to make an absolute statement about the
accumulation of lindane to be about 28x greater in the presence of
Aroclor 5460® would be tenuous. It can be stated that there was a
subtle effect of the plasticizer as identifiable amounts of lindane
were found in the present experiment in the algae, 6.18 ppm; Daphnia,
2.17 i>pm; snail, 5.66 ppm and mosquito, 4.21 ppm. Without the Aroclor
5460JV, no lindane was found in the algae or mosquito, but substantial
amounts were found in the snail, 0.762 ppm, and fish, 0.975 ppm (Metcalf
et al., 19731. Clearly, this preliminary experiment with lindane and
Aroclor 5460») demonstrates the potentiality for studying the interactions
of compounds. In a recent investigation it has been demonstrated that
piperonyl butoxide (pb), an insecticide synergist, will increase both
the total radioactivity in the snail and fish as well as the concentra-
tion of methoxychlor in these two organisms (Metcalf, 1973).
Other data of interest in the metabolite distribution from the organisms
is that neither of the two chlorinated phenols, 2,4,6-trichlorophenol
or 2,4,5-trichlorophenol, were found in the organisms, while small
amounts were found in the water which will be discussed next. These
two chlorinated phenols have been reported as urinary excretion products
when rats were fed lindane (Grover and Sims, 1965). A final point that
should be made is the low percentage of unextractable radioactivity
(average 7%) in the organisms. This figure is similar to the value for
dieldrin and about one-tenth of the amount obtained for the carbamate
and phosphate insecticides. The data for the previous experiment with
lindane in this model ecosystem also indicate a low amount of unextract-
able radioactivity, which would seem to imply that the addition of the
20
-------
Table 10
Concentrations (ppm) of lindane and Aroclor 54603$ and metabolites
in organisms in a model ecosystem
Compound
•A
1 indane
B
C
I*/
II
Extractable ^C
Unextractable ^C
Grand Total 14C
Rf^7
0.75
0.40
0.19
0.13
0.06
0.00
Algae
--
6.178
--
--
--
0.285
6.463
0.803
7.266
Daphnia
--
2.166
--
--
--
0.127
2.293
0.164
2.457
Fish
0.025
26.379
--
--
--
1.004
27.408
0.087
27.495
Mosquito
--
4.212
--
--
--
0.108
4.320
0.309
4.629
Snail
--
5.658
--
--
0.110
0.410
6.178
0.522
6.700
£/ Silica Gel GF-254, petroleum ether-carbon tetrachloride,1:1 by volume
k_/ Roman numerals - unknown spots
A pentachlorocyclohexene
B 2,4,6-trichlorophenol
C 2,4,5-trichlorophenol
-------
Table 11
Concentrations (ppm) of lindane and Aroclor 5460*'
and metabolites in water in a model ecosystem
Compound
R
i/
Unhydrolyzed Water
Hydrolyzed Water
A
lindane
B
C
&
II
Extractable ^C
Unextractable ^C
Grand Total ^C
0.75
0.40
0.19
0.13
0.06
0.00
0.0000608
0.0125
0.000471
0.000418
0.000433
0.00124
0.01520
0.00740
0.0226
--
—
0.000056
0.000182
0.000352
0.00144
0.00202
0.00430
0.00632
2.1 Silica Gel GF-254, pet ether-carbon tetrachloride, 1:1 by volume
—' Roman numerals - unknown spots
A pentachlorocyclohexene
B 2,4,6-trichlorophenol
C 2,4,5-trichlorophenol
22
-------
polychlorinated terphenyl does not affect the metabolism of lindane to
polar, unextractable metabolites.
The distribution of metabolites in the water (Table 11) for this experi-
ment of lindane and Aroclor 5460© is somewhat different than if lindane
'^Ls put through the system alone. The most striking difference is the
greater quantity of lindane, 0.0126 ppm, found in the present experiment
as compared to 0.00167 ppm (Metcalf et a±., 1973), which is an increase
of about 7.5x. Further, in the present experiment it was possible to
identify small amounts of 2,4,6-trichlorophenol, 0.00053 ppm and
2,4,5-trichlorophenol, 0.0006 ppm. If the concentration of lindane
isolated from the water is divided into the fish and snail, concentra-
tion factors are derived of ^jlOOx and 448x, respectively. The value
obtained for the fish is about 4x that obtained for the fish for
lindane alone (Metcalf et al., 1973), while the snail value in the
present experiment is nearly identical. The interaction of pesticides
and other chemicals, such as a polychlorinated terphenyl, give results
that are complex and difficult to interpret. Finally, the unextractable
radioactivity from the water for the lindane experiment alone was about
2.5% (Metcalf et^ a^., 1973), while the unextractable radioactivity from
the present experiment amounted to 26%. The effect of Aroclor 54605' on
the metabolism, degradation and persistence of lindane in the water is
a 10-fold increase in unextractable radioactivity.
Ortheneffi
OrtheneB) is a new organophosphate insecticide which shows moderate
persistence and a residual activity of 5-10 days. In field trials con-
ducted from 1968 to 1972 this insecticide was effective in controlling
pest species of aphids and lepidopterous larvae. In contrast to
parathion, this phosphoramidothioate insecticide shows a low order of
toxicity to higher animals as the LD5Q to male rats is about 945 mg/kg,
which is about lOOx less toxic than parathion. In addition, the 96-hr
TLijQ for Orthene® is greater than 1,000 ppm for trout, 1,725 ppm for
large-mouth bass, 2,050 ppm for blue gill, 2,230 for channel catfish,
6,650 for mosquito fish (Gambusia) and 9,550 ppm for goldfish. The
preceding data, which was taken from the technical data sheet available
from the Chevron Chemical Company (1972) indicates that this material
is safe in terms of acute toxicity to both fish and mammals.
The metabolism pathways of this insecticide have not been published, but
a number of possibilities for potential metabolites and/or degradation
products can be hypothesized. The loss of the N-acetyl group to give
0,j>-dimethyl phosphoramidothioate, another Chevron Chemical Company
product, Monitoifiy, is an obvious metabolite as similar transformations
are known to occur from metabolism studies on N-derivatized carbamates
(Miskus et^ al., 1969). This transformation to Monitor® results in a
more toxic molecule to the rat as the LD5Q of this compound is 18.9
mg/kg (Chevron Chemical Company, 1972). Another transformation that
OrtheneS) might undergo is cleavage of either the j5-methyl or 0-methyl
moieties to yield the j>-methyl acetamidophosphorothioic acid or
23
-------
0_-methyl acetamidophosphoric acid, respectively. The cleavage of
either S^-methyl or ()-methyl could occur after loss of the acetyl moiety
from nitrogen to yield either 0-methyl phosphoramidic acid or j>-methyl
phosphoramidothioic acid. One final transformation that could occur is
the removal of the amino group after loss of the acetyl group to yield
0_,^-dimethyl phosphorothioic acid.
Examination of the data in Tables 12 and 13 for the organisms and water,
respectively, shows that none of the chromatographed metabolites were
found in identifiable quantities in the organisms. An unusual
occurrence was the formation of a degradation product which was less
polar than Orthene®, which had an Rf of 0.70, or Monitoi®, which had an
Rf of 0.79. This metabolite varied in concentration from about 0.26
ppm in Daphnia to greater than 2.0 ppm in the crab. Since the site of
the label was ^C j>-methyl, perhaps this nonpolar species is not related
to OrtheneB), but has been utilized as a source of carbon in a structural
entity in the organism from which it was isolated.
Finally, as was previously indicated for the carbamate insecticide, the
unextractable radioactivity in the organisms for Orthene® was high at
about 72%. This indicates that this insecticide breaks down over the
time period of the model ecosystem to nonlipid—partitioning products.
The only product which appears in the organisms is nonpolar (Rf, 0.93)
and does not appear to be deleterious. It is not surprising to find
that Orthene does not accumulate in the organisms of this system as
the water solubility of this insecticide is reported to be about 650,000
ppm (Chevron Chemical Company, 1972).
In the water of this model ecosystem (Table 13) were small amounts of
Orthene®, 0.000282 ppm, and as well as small quantities (0.000478 ppm)
of the unknown which was nonpolar and had an Rf value of 0.93. This
nonpolar species was accumulated from the water by the various organ-
isms from 538x for Daphnia to about 4,300x for the crab. Trace amounts
of Monitoisy, 0.000124 ppm, and the ammonium salt of JJ-methyl acetyl-
phosphoramidothioate, 0.000015 ppm, were found in the hydrolyzed water.
Finally, the high value found for the unextractable radioactivity in
unhydrolyzed water, >99%,and hydrolyzed water, ^97%, indicates the
susceptibility of Orthenely to undergo degradation to metabolites of
high water solubility.
Parathion
Parathion is a member of the first generation of organophosphorus
insecticides used in the United States. It was originally discovered
in Germany by Gerhard Schrader during World War II and since then has
been used for the control of insects which are pests of many crops.
The large-scale use of parathion is indicated by the 15,259,000 pounds
manufactured in the United States in 1970. While there does not seem
to be environmental problems associated with the use of parathion,
nevertheless it is paramount that insecticides that are highly toxic to
warm-blooded animals (oral 11)50, rats 4-13 mg/kg) be .examined to
24
-------
Table 12
Ol
Concentrations (ppm) of OrtheneS' and metabolites in organisms
in a model ecosystem
Compound
£>
A
Orthen<®
B
C
II
III
IV
Extractable 14C
Unextractable ^C
Grand Total 14C
Rf-' Algae Clam Crab Daphnia Elodea Fish Mosquito Snail
0.93 0.936 -- 2.038 0.257 0.408 -- 0.797 0.796
0.79
0.70
0.45
0.33
0.25 0.0538
0.11 0.0142 -- -- -- 0.00280
0.00 0.0395 -- 0.247 0.143 0.0098 -- 0.0247 0.130
1.043 0.100 2.284 0.400 0.421 0.0309 0.822 0.927
3.517 0.148 3.631 1.979 1.435 0.0621 2.466 2.769
4.560 0.248 5.915 2.379 1.856 0.0930 3.288 3.696
— Silica Gel GF-254, aluminum plate in 15% acetic acid in benzene-propanol, 1:1 by volume
—' Roman numerals - unknown spots
A 0,jS-dimethyl phosphoramidothioate
B 0,^-dimethyl phosphorothioate sodium salt
C B_-methyl IJ-acetylphosphoramidothioate ammonium salt
-------
Table 13
Concentrations (ppm) of OrtheneS' and metabolites
in water in a model ecosystem
Compound
rW
A
Orthene®
B
C
II
III
IV
Extractable
14,
Unextractable
Grand Total
Unhydrolyzed Water Hydrolyzed Water
0.93 0.0000617
0.79
0.70 0.0000484
0.45
0.33
0.25
0.11
0.00
0.00011
0.0376
0.0377
0.000416
0.000124
0.000234
--
0.0000150
--
--
0.0000255
0.00082
0.0236
0.0244
—' Silica Gel GF-254, aluminum plate in 15% acetic acid in benzene-
propanol, 1:1 by volume
]>/ Roman numerals - unknown spots
A (),j>-dimethyl phosphoramidothioate
B 0,j>-dimethyl phosphorothioate sodium salt
C ^-methyl II-acetylphosphoramidothioate
26
-------
determine their persistence in the model ecosystem. Further, the
investigation of pesticides in this model ecosystem, such as parathion
which has had widespread use without apparent accumulation in food
chains, is necessary so that field and model ecosystem data can be
compared to test the validity of the model ecosystem as a screening
for pesticide persistence.
The metabolism of parathion has been thoroughly studied in animals and
somewhat less detailed studies have been carried out in plants and soil.
Briefly, the major alterations of parathion are oxidation to paraoxon
and cleavage of parathion to diethylphosphorothioic acid and _p_-
nitrophenol. Paraoxon can undergo ()-dealkylation to ^-ethyl,
0-jD-nitrophenyl phosphoric acid as well as cleavage to diethyl phos-
phoric acid and _p_-nitrophenol.
The model ecosystem study with parathion demonstrates the rapid break-
down of this insecticide as the data in Tables 14 and 15 show that this
phosphate does not persist to any great extent nor does it accumulate
in the fish as was observed for the chlorinated hydrocarbon, dieldrin.
Only the fish (0.100 ppm) contained parathion as all the other organisms
had neither parathion, paraoxon nor j>-nitrophenol. Therefore, it was
Possible to establish the fate of j>-nitrophenol since the site of the
4-C label was in the 2,6-positions of this moiety. It would seem
important to establish the fate of j>-nitrophenol and other phenols in a
model ecosystem as they are significant constituents of a number of
organophosphorus insecticides. Again as previously discussed for the
phosphate insecticide, Orthene®, and the three carbamates in this
report, substantial amounts of the radioactivity, with the exception of
the fish, was unextractable (average 65%) . An explanation for the
relatively high amounts of extractable radioactivity (81%) in the fish
is the low microsomal activity in the liver of Gambus ia (Krieger and
Lee, 1973) which does not metabolize parathion to polar, unextractable
products.
The water segment (Table 15) of the ecosystems contains small amounts
of parathion, 0.0003 ppm; paraoxon, 0.00047 ppm; and j>-nitrophenol,
0.00095 ppm. In addition, there were small amounts of unknown metabo-
lites which had Rf values of 0.97, 0.73, 0.33, 0.09, 0.13 and 0.00.
The accumulation of parathion by the fish over the concentration in the
water was about 335x, which is about 0.054 the value observed for
dieldrin in this model ecosystem. Probably, the higher water solubility
of parathion, 25 ppm (Gunther et^ al^. , 1968), as compared to dieldrin,
0.25 ppm (Gunther a£ aJ. , 1968), and the greater susceptibility of
parathion to undergo degradation account for the substantially less
concentration of parathion by the fish in this model ecosystem. The
portion of unextractable radioactivity in the water was smaller than
for Orthene®, as it averaged about 40%. Perhaps this decrease from
approximately 98-99% for Orthene® indicates that parathion, as compared
to Orthene®, is less degradable and therefore more persistent in the
aqueous compartment of this model ecosystem.
27
-------
N3
00
Table 14
Concentrations (ppm) of parathion and metabolites in organisms
of a model ecosystem
Compound
&
parathion
A
III
VI
Extractable ^C
Unextractable ^C
Grand Total 14C
Rf-
0.97
0.90
0.55
0.33
0.00
Algae
0.0356
--
--
--
0.3613
0.3969
2.6284
3.0253
Daphnia
--
--
--
--
0.2987
0.2987
0.3126
0.6113
Fish
--
0.1006
0.0086
0.0222
0.0621
0.1935
0.2055
0.3990
Mosquito
--
--
--
--
0.2031
0.2031
0.4685
0.6716
Snail
--
--
--
--
0.2701
0.2701
0.5818
0.8518
a/
- Silica Gel GF-254, diethyl ether-n-hexane, 7:3 by volume
SL' Roman numerals - unknown spots
A j3-nitrophenol
-------
Table 15
Concentrations (ppm) of parathion and metabolites
in water of a model ecosystem
Compound
i
parathion
II
P.-NC-2 phenol
III
paraoxon
IV
V
VI
Extractable 14C
Unextractable ^C
Grand Total 14C
Rf*.'
0.97
0.90
0.73
0.55
0.33
0.25
0.13
0.09
0.00
Unhydrolyzed Water
0.00020
0.00030
0.00006
0.00074
0.00018
0.00031
0.00049
0.00151
0.00222
0.00661
0.0144
0.0210
Hydrolyzed Water
--
--
--
0.00062
0.00007
0.00016
--
0.00123
0.00377
0.00585
0.00853
0.01438
^•'l Silica Gel GF-254, ether-hexane, 7:3 by volume
— Roman numerals - unknown spots
29
-------
SECTION IV
EXAMINATION OF SELECT HERBICIDES
The second aspect of this report is concerned with the fate of several
herbicides in this model ecosystem. While the acute toxicity of most
herbicides to mammals is low, it still is necessary to derive informa-
tion which can be used as a predictive measure of the potential for
these pest chemicals to accumulate and persist in the environment.
Therefore, the next section should provide information about several
members of this class of pesticide chemicals. It is hoped that
additional herbicides can be examined in this system, particularly
those which currently have a widespread use, so that a baseline can be
established for the comparison of new herbicides.
Alachlor and Propachlor
Since alachlor and propachlor have similar structures chemically,
namely, 2-chloroacetanlides, the discussion of these two compounds and
their behavior in the model ecosystem will be combined. Both compounds
are safe in terms of acute toxicity as the oral H>50 values for
alachlor and propachlor are 1,200 mg/kg and 1,500 mg/kg, respectively.
The soil persistence of these two herbicides is 1-2 months which is
quite short. The principal use has been in the control of weeds in
corn as preemergence, preplant or postemergence treatments. The mode
of action of propachlor in susceptible plants appears to be the inhibi-
tion of utilization of proteinacous and lipid reserves which are
necessary for plant growth (Dhillion, 1971).
Some work on the metabolism of these herbicides in soil and plants has
been carried out, but it is by no means extensive. Laboratory studies
in soil indicates the primary degradative route for alachlor is loss of
the -CH2OCH3 moiety from nitrogen (Hargrove and Merkle, 1971). This
transformation is believed to take place on the acidic soil surface.
Higher relative humidity decreases the herbicide contact with the soil
surface which then decreases the rate of this transformation. Metabo-
lism of propachlor by corn, sorghum and sugarcane plants yields a
conjugate of glutathione as a primary metabolite (Lamoreaux and Tanaka,
1971).
The data for these two herbicides for the organisms contained in Tables
16 to 19 reveal conclusively the lack of uptake of either of these two
herbicides by any of the organisms. The water had numerous unidentified
metabolites which were not in the organisms as well as small amounts of
the parent compounds, 0.0564 ppb for propachlor and about 1.05 ppb for
alachlor. The 2-chloro group of the acetanilde is a labile moiety and
could undergo displacement to yield a substantially more water soluble
moiety, though no metabolite was available for co-chromatography. In
addition, as evidenced by the approximately 17 unidentified compounds,
it can be stated that both of these herbicides are susceptible to
degradation to water-soluble, nonlipid-partitioning organic compounds.
30
-------
Table 16
Compound
Concentrations (ppm) of alachlor and metabolites in organisms
in a model ecosystem
Algae
Crab
&
alachlor
II
III
IV
V
VI
VII
VIII
IX
Extractable ^C
Unextractable ^C
Grand Total ^C
0.70
0.61
0.51
0.43
0.33
0.27
0.20
0.13
0.07
0.00
__
__
-_
--
.-
__
__
__
__
-_
0.0898 0.321
0.569 0.524
0.658 0.845
Daphnia
0.000
0.422
0.422
-' Silica Gel GF-254, methanol-benzene, 5:95 by volume
—' Roman numerals - unknown spots
Elodea
1.767
2.961
4.728
Fish
0.125
0.106
0.231
Mosquito Snail
0.0452
0.244
0.289
0.658
0.185
0.843
0.544
1.387
-------
Table 17
Concentrations (ppm) of alachlor and metabolites
in water in a model ecosystem
Compound
£>
alachlor
II
III
IV
V
VI
VII
VIII
IX
Extractable 14C
Unextractable ^C
Grand Total ^C
2.1 Silica Gel GF-254,
^_* *D x"**ti «i T-I TT*I ivmA v O 1 f* — tii
a/
R — Unhydrolyzed Water Hydrolyzed Water
0.70
0.61
0.51
0.43
0.33
0.27
0.20
0.13
0.07
0.00
0.000271
0.00105
0.00190
0.0105
0.000777
--
0.000832
0.00172
0.000687
0.000362
0.0181
0.0414
0.0595
me thanol -benzene, 5:95 by volume
i^I>-T"» fwsivi c* v*r\ 4~ r*
0.000677
--
0.00154
0.00364
0.00146
--
0.00854
--
0.00300
0.00465
0.0212
0.0118
0.0330
32
-------
Table 18
Concentrations (ppm) of propachlor and metabolites in organisms
in a model ecosystem
Compound.
D /
ii
propachlor
III
IV
V
VI
VII
VIII
Extractable 14C
Unextractable ^4(
Grand Total 14C
R / A i O 3 O f T OTn T^ £1 fl^lT"! ^ 3
i?— AXgcLc Vji.a.Ul i/a.pLirHa.
0.69
0.62
0.55
0.40
0.30
0.27-0.15
0.10
0.03
0.00
0.0211 0.00619 0.00930
] 0.186 0.00886 0.0476
0.207 0.0150 0.0569
Elodea Fish Mosquito Snail
--
_-
--
--
0.0154
--
--
--
0.0595
0.00243 0.00605 0.0264 0.0749
0.0869 0.00854 0.134 0.177
0.0893 0.0146 0.160 0.252
£/ Silica Gel GF-254, methanol-benzene, 5:95 by volume
—' Roman numerals - unknown spots
-------
Table 19
Concentrations (ppm) of propachlor and metabolites
in water in a model ecosystem
Compound
I^7
II
propachlor
III
IV
V 0
VI
VII
VIII
Extractable ^C
Unextractable ^C
Grand Total 14C
^ Silica Gel GF-254
_' Roman numerals -
R — Unhydrolyzed Water Hydro ly zed Water
0.69
0.62
0.55
0.40
0.30
.27-0.15
0.10
0.03
0.00
--
0.0000614
0.0000564
0.00125
--
0.000144
0.0000830
0.0000216
0.0000382
0.00166
0.0121
0.0138
0.0000622
0.000108
--
0.00193
--
0.000277
0.000189
0.000297
0.00390
0.00676
0.00414
0.0109
, me thanol -benzene, 5:95 by volume
unknown s not
s
34
-------
Bladdg)
Bladex® is a member of the ^-triazine structural class of herbicides
which has found use for the control of annual grasses and broadleaf
weeds in corn as a preemergence treatment. The preemergence treatment
for corn with Bladej«y is preferred as injury often results when the
^herbicide is put on after the corn has emerged. Under normal agricul-
tural usage (1-4 Ib/A) the half-life varied between 2-7 weeks, while
laboratory half-life on three typical soils was about 15 days. The
toxicity to fish and birds is low, which correlates with the oral LD5Q
of 334 mg/kg obtained for rats.
The metabolism of Bladej® in rats (Hutson et: al., 1970) and degradation
in soil have been examined (Beynon et al., 1972). The principal
metabolites in rat urine are the N-desethylated Bladex® and replacement
of the 2-chloro group with an N-acetyl cysteine which is conjugated
through a sulfur linkage. The degradation in the soil is more compli-
cated as the nitrile is hydrolyzed to the amide and, finally, the acid.
The Cl group is replaced by OH and also N-desethylation takes place.
The data for the distribution of Bladex® in the organisms and degrada-
tion products are contained in Table 20. With the exception of Elodea,
which contained 0.621 ppm Bladex® and the crab with 0.172 ppm of the
N-desethylated Bladex®, none of the other organisms had residues of
identifiable metabolites. The organisms contained extractable radio-
activity which ranged from a low of 00.02 ppm for Daphnia to a value of
0.629 ppm for Elodea. Significantly, of this 0.629 ppm isolated from
the water plant, nearly 99% was intact BladexB). The level of
unextractable radioactivity from the organisms averaged 48%, indicating
a substantial degree of degradation of this herbicide.
The water portion of this ecosystem (Table 21) is interesting in terms
of the distribution of degradation products as several were present in
indentifiable amounts along with BladexS/ which was found at 3.2 ppb.
Two others which were found were the amide at 1.42 ppb and the
N-desethylated amide at 0.0568 ppb. In addition to these degradation
products, there were several unidentified materials at levels of
0.014-0.028 ppt. Clearly, none of the metabolites isolated from the
water appears in any of the organisms, which indicates that neither
BladexB/nor any of its metabolites accumulate in the organisms of this
model ecosystem.
Bentazor
Bentazor® is a new herbicide that is being developed as a broadleaf
weed control for application as a postemergence treatment. There is
little published information about the metabolism of this herbicide or
its behavior in the soil environment. Recently, a study was conducted
to determine the affinity of BentazoiUy for 12 Illinois soils and the
data indicate that it does not bind tightly to any of them (Abernathy
and Wax, 1973).
35
-------
Table 20
Compound
Bladex®
A
B
C
II
III
Extractable ^C
Unextractable ""C
Grand Total 14C
Concentrations (ppm) of BladexS) and metabolites in organisms
in a model ecosystem
St 1
n ci /
0.55
0.47
0.37
0.26
0.16
0.07
0.00
Algae Crab
__
0.172
__
__
_.
0.0579
0.0812
0.129 0.311
0.127 0.209
0.256 0.520
Daphnia Elodea
0.621
__
__
__
__
__
0.00818
0.0196 0.629
0.0202 0.0253
0.0398 0.654
Fish
0.0354
0.0157
0.0511
Mosquito Snail
0.0277
0.0751
0.103
0.0454
0.0624
0.108
2. Silica Gel GF-254, methanol-acetone-chloroform, 5:45:50 by volume
—' Roman numerals - unknown spots
A 2-chloro-4-amino-6-(l-methyl-l-cyanoethylamino) -j^-triazine
B 2-chloro-4-ethylamino-6-(l-methyl-l-carboxamidoethylamino)-£-triazine
C 2-chloro-4-amino-6-(l-methyl-l-carboxamidoethylamino) -s.-triazine
-------
Table 21
Concentrations (ppm) of Blades® and metabolites
in water in a model ecosystem
Compound
Unhydrolyzed Water
Hydrolyzed Water
0.55
0.47
0.37
0.26
0.16
0.07
0.00
0.00321
0.0107
0.000142
0.0000568
0.0000142
0.0000142
0.0000284
0.0142
0.00359
0.0178
—
--
--
--
0.0000626
0.0000726
0.0000250
0.00016
0.00357
0.00373
A
B
C
I
II
III
Extractable
Unextractable
Grand Total 14C
a/
—' Silica Gel GF-254, methanol-acetone-chloroform, 5:45:50 by volume
— Roman numerals - unknown spots
A 2-chlor-4-amino-6-(l-methyl-l-cyanoethylamino) ^s_-
B 2-chloro-4-ethylamino-6-(l-methyl-l-carboxamidoethylamino)-s_-triazine
C 2-chloro-4-amino-6-(l-methyl-l-carboxamidoethylamino)-j3-triazine
37
-------
The data for the distribution of metabolites and degradation products
of Bentazoi® in the organisms of the model ecosystem are compiled in
Table 22. The crab was the only organism that contained metabolites,
including BentazorUV at 0.512 ppm, anthranilic acid at 1.27 ppm and
14-isopropyl anthranilamide at 0.622 ppm. Most of the other organisms
contained small amounts of W-C labeled extractable metabolites that
were in such low concentration identification was not possible.
The data for the degradation products in the water segment of the eco-
system are collected in Table 23. The water contained 0.0213 ppm of
IJ-isopropyl anthranilamide and 0.0505 ppm of Bentazon®, but no
anthranilic acid. Several metabolites and Bentazon®were accumulated
from the water to a slight extent by the crab as both N-isopropyl
anthranilamide and Bentazori® were higher in concentration in the crab
than in the water.
Dicamba
Dicamba is an effective'herbicide for numerous annual grasses and
broadleaf weeds in grain crops. It is more persistent in the soil than
2,4-D which was essentially degraded in sandy loam and loam after two
weeks; but dicamba after 12 weeks was still highly active (Friesen,
1965). Dicamba in high organic soils is detoxified rapidly at pH 5.3,
but appears to be highly persistent at pH 7.5. An explanation for this
is the increase proliferation of soil bacteria at the lower pH which
are capable of degrading the herbicide (Swanson, 1969). This herbicide
is not toxic to the rat, LD5Q 1,028 mg/kg, nor to rainbow trout as the
24 hr TLm is 35,000 ppm (Herbicide Handbook, 1970).
The metabolism of dicamba has been investigated in wheat and bluegrass,
and the major degradation product is 5-hydroxy dicamba which then is
conjugated (Broadhurst e_t a±,, 1966). Further; transformations in
these two plant species include conjugation of dicamba and
()-demethylation to give 3,6-dichlorosalicylic acid. Metabolism studies
of dicamba with ring-labeled l^C dicamba in rats demonstrate that this
herbicide is rapidly excreted in the urine with approximately 20% of
the urinary metabolites in the form of glucuronic acid conjugates (Tye
and Engel, 196_7) . Feeding studies with dicamba in rats reveal that
most residues were in the aqueous portion of the body burden and not in
fatty tissues, indicating this herbicide is not stored (Tye and Engel,
1967).
The picture that emerges from examination of dicamba in the model eco-
system for the organisms as seen in Table 24 is that none of the
organisms contains residues of identifiable metabolites. Only the crab
contains 0.743 ppm of an unidentified conjugate, while the rest of the
organisms have small amounts of extractable radioactivity and somewhat
larger amounts of unextractable radioactivity. Clearly, dicamba or its
metabolites do not accumulate in the organisms of this model ecosystem.
38
-------
Table 22
vo
Concentrations (ppm) of Bentazofl^and metabolites in organisms
in a model ecosystem
Compound
A
B
BentazonB)
iV
Extractable 14>C
Unextractable ^C
Grand Total 14C
Rf— ' Algae
0.77
0.63
0.52
0.00
0.109
0.759
0.868
Clam
--
--
--
--
0.032
0.021
0.054
Crab
0.622
1.266
0.510
0.327
2.72
3.08
5.80
Daphnia
--
--
--
--
0.182
0.407
0.98
Elodea
--
--
--
--
0.092
0.168
0.26
Fish
--
--
--
--
0.012
0.036
0.048
Mosquito
--
--
--
--
0.146
0.716
0.86
Snail
--
--
--
--
0.084
0.378
0.462
—/Silica Gel GF-254, benzene-ethanol, 60:40 by volume
—'Roman numerals - unknown spots
A N-isopropyl anthranilamide
B anthranilic acid
-------
Table 23
Concentrations (ppm) of BentazonB/and metabolites
in water in a model ecosystem
a/
Compound Rf— Unhydrolyzed Water
A 0.77
B 0.63
Bentazoi® 0.52
]£/ 0.00
Extractable ^C
Unextr actable l^C
Grand Total 14C
0.000691
--
0.000281
0.000028
0.001
0.114
0.116
Hydrolyzed Water
0.0207
--
0.0502
0.00303
0.074
0.44
0.118
—I Silica Gel GF-254, benzene-ethanol, 60:40 by volume
.k/ Roman numerals - unknown spots
A N-isopropyl anthranilamide
B anthranilic acid
40
-------
The water portion of this model ecosystem (Table 25) contains small
amounts of unconjugated dicamba, 0.000289 ppm, and about l,800x that
amount in the hydrolyzed water, 0.162 ppm. The dicamba isolated after
hydrolysis was a conjugate which was released through the acid treat-
ment. Also there were small amounts of 5-hydroxy dicamba, 0.0185 ppm,
released on treatment of the water with acid. The tendency for this
herbicide to become conjugated in the water portion of this ecosystem
is exemplified by the comparative figures for unextractable/extractable
i^C. For the unhydrolyzed water, >99% was in the form of unextractable
radioactivity, while in the hydrolyzed water about 9970 became extract-
able after acid hydrolysis. In the hydrolyzed extract 89% of the
radioactivity was dicamba.
2,4-dichlorophenoxyacetic acid
The herbicidal properties of 2,4-dichlorophenoxyacetic acid (2,4-D and
its esters) have been known for over 30 years. In view of the lengthy
use of this herbicide and the availability of an excellent review of
this class of herbicidal chemicals (Loos, 1969), few comments will be
made about their mode of action. In general, metabolism and degradation
studies that have been carried out in plants indicate three generalized
metabolism pathways, namely, ring hydroxylation, side chain degradation
and conjugation of the acid or phenolic moieties (Loos, 1969). Princi-
pal hydroxylated metabolites found in plants of 2,4-D are 2,3-dichloro-
4«»hydroxyphenoxyacetic acid and 2,5-dichloro-4-hydroxyphenoxyacetic
acid which result from a chlorine shift during hydroxylation. The side
chain metabolism has been demonstrated through the use of ^C labeled
2,4-D and trapping of the ^C02 produced by oxidation of the side chain.
Finally, conjugates of the ring hydroxylated metabolites and intact
2,4-D with glucose appear to be an important mode of detoxication of
this herbicide by plants (Loos, 1969). In addition to the characterized
metabolites, numerous unidentified metabolites from plants have been
observed and corroborate the observation from the present model
ecosystem work that this chemical can undergo substantial degradation.
The degradation of 2,4-D in the soil by microorganisms is optimal in
warm, moist soil. Autoclaving of the soil destroys the bacteria and
reduces the rate of degradation of 2,4-D. Primary degradation routes
of the phenoxyacetic acids appear to go in two stages, namely,
degradation to the phenol and then degradation of the phenol to carbon
dioxide and water (Loos, 1969).
With regards to the environmental accumulation of 2,4-D by fish in an
aquatic food web, a recent study (Schultz, 1973) has provided insight
into the uptake of this herbicide by fish. In general, the three
species of fish exposed to this herbicide did not accumulate it over
the concentration in the water. As would be expected, fish exposed to
the herbicide in water held at pH 9 contained less residues of 2,4-D
than those exposed at pH 6. Further, less than 10% of the radioactivity
accumulated by the fish was parent material and the major metabolite
41
-------
Table 24
S3
Concentrations (ppm) of dicamba and metabolites in organisms
in a model ecosystem
Compound
dicamba
A
B
Extractable 14C
Unextractable ^C
Grand Total 14C
Rf-' Algae
0.86
0.38
0.04
0.228
1.390
1.618
Clam Crab
Daphnia Elodea
Fish
Mosquito Snail
0.743
0.0128 0.743
0.0144 0.374
0.0272 1.117
—' Whatman No. 1 filter paper, benzene-acetic acid, 2:1 by volume
A 3,6-dichloro-5-hydroxy-2-methoxy benzoic acid
B Conjugated metabolite
0.000
0.167
0.167
0.325
0.593
0.918
0.00665
0.0122
0.0188
•* •»
0.0736
0.281
0.355
0.0720
0.252
0.324
-------
Table 25
Concentrations (ppm) of dicamba and metabolites
in water in a model ecosystem
Compound
d icamba
A
B
Extractable
Unextractable
Grand Total
14,
RjS'
0.86
0.38
0.04
Unhydrolyzed Water
0.000289
--
0.0000114
0.000300
0.163
0.163
Hydro lyzed Water
0.162
0.0185
0.000181
0.181
0.0022
0.183
a/
—' Whatman filter paper No. 1, benzene-acetic acid, 2:1 by volume
A 3,6-dichloro-5-hydroxy-2-methoxy benzoic acid
B Conjugated metabolite
43
-------
was the glucuronic acid conjugate of 2,4-D. The small amounts of 2,4-D
found in the fish demonstrate that the fish can metabolize this
herbicide.
The model ecosystem experiment confirmed the earlier work regarding the
propensity for 2,4-D to undergo substantial degradation and not accumu-
late in aquatic organisms. For example in Table 26 for the organisms,
there were no residues of 2,4-D and seven unidentified metabolites.
The substantial numbers of unidentified metabolites are disturbing as
six metabolites, including 2,4-D, were co-chromatographed with the
extracts from these organisms. The compounds chromatographed were
2,4-D, 2,3-dichloro-4-hydroxyphenoxyacetic acid, 2,4-dichloro-5-
hydroxyphenoxyacetic acid, 2,5-dichloro-4-hydroxyphenoxyacetic acid,
2,4-dichlorophenol, 3,5-dichlorocatechol, 2,3-dichlorohydroquinone and
2,3-dichlororesorcinol.
The water portion of the model ecosystem experiment (Table 27) had
numerous spots which did not correspond to any of the chromatographed
metabolites. Interestingly, the water primarily contained metabolites
which had Rf values of 0.58 or less, while the snail, algae and Elodea
contained metabolites and/or degradation products with higher Rf values.
This is expected as polar products remain in the water and less polar
materials partition into the organisms. Clearly, 2,4-D does not
accumulate in any of the organisms of this model ecosystem and appears
to be degraded into water soluble compounds.
Pyrazon
Pyrazon is a herbicide used for the control of annual broadleaf weeds
in sugar beets and red beets. The usual modes of application are as a
preemergence, broadcast or early postemergence as a banded treatment at
2-4 Ib/A. This herbicide is relatively nontoxic to mammals as the oral
LD5Q to the rat is 3,000 mg/kg (Anon. 1973). It does not leach readily
through clay, clay loam or sandy clay and loam soils and has a soil
persistence time of about 1-2 months (Frank, 1972). The mode of action
in the susceptible plant, lambsquarters, is inhibition of the Hill
Reaction which is important in photosynthesis. However, in vivo com-
parison of the metabolic rates of sugar beets, which are nonsusceptible,
and lambsquarters, which are susceptible, shows that pyrazon accumulates
in the stems and leaves in the susceptible species, while in the
tolerant sugar beets the pyrazon is rapidly degraded to nonphytotoxic
species. Hence, the selectivity in vivo in the comparison of sugar
beets and lambsquarters lies in the greater ability of the sugar beets
to degrade pyrazon (Frank, 1972).
The metabolism of pyrazon in plants and soil has been examined. In
sugar beets the herbicide was degraded to three primary metabolites,
two of which were positively identified. The two identified were the
conjugate with the free amino group with glucose to form N-glucosyl
pyrazon and desphenyl pyrazon. In the soil the only metabolite
identified was the desphenylated pyrazon (Stephensen and Ries, 1969).
44
-------
Table 26
Concentrations (ppm) of 2,4-D and metabolites
in organisms in a model ecosystem
Compound
.*/
II
III
VI
V
X
XII
Extractable ^C
Unextractable 14-C
Grand Total 14C
^ Silica Gel GF-254,
_' Roman numerals - 111
RfS'
0.97
0.89
0.80
0.65
0.58
0.10
0.00
Algae
0.282
1.0295
0.477
0.377
0.295
1.675
1.362
5.498
17.625
23.123
benzene-dioxane-acetic acid,
ilrnown snof-R
Elodea
0.178
0.456
0.447
--
--
0.768
0.873
2.722
7.755
10.477
90:25:4 by volume
Fish
0.0431
0.00226
0.0454
0.211
0.256
Snail
0.285
0.301
0.171
0.757
6.421
7.178
-------
Table 27
Concentrations (ppm) of 2,4-D and metabolites
in water in a model ecosystem
Compound
VI
VII
VIII
IX
X
XI
XII
Extractable
14r
Unextractable
Grand Total
Unhydrolyzed Water Hydrolyzed Water
0.58
0.63
0.56
0.49
0.39
0.10
0.067
0.00
0.000029
0.0000914
0.0000658
--
--'
--
--
0.00000496
0.000191
0.0128
0.0130
0.0000351
0.00260
0.00205
0.00226
0.000417
0.000474
0.000271
0.000180
0.000829
0.0120
0.0128
— Silica Gel GF-254, benzene-dioxane-acetic acid, 90:25:4 by volume
—' Roman numerals - unknown spots
46
-------
The data for the distribution of metabolites and degradation products
in the organisms of pyrazon are in Table 28. Again, as in the case of
the 2-chloroacetanilides, no identifiable compounds with the exception
of the crab, 0.476 ppm, had residues of either pyrazon or degradation
products. Further, very little of the radioactivity (extractable and
taaextractable) was isolated from any of the organisms (0.0573 ppm for
fish to 0.629 ppm for crab), which may be explained by the relatively
high water solubility of pyrazon, 300 ppm (Anon. 1970).
The water portion of this ecosystem (Table 29) contains five unidenti-
fied metabolites not found in the organisms, including pyrazon at
0.212 ppm and the desphenyl pyrazon at 0.0714 ppb. Clearly, pyrazon
shows a similar pattern to the 2-chloroacetanilides as it is not
accumulated by the organisms of the model ecosystem, but degrades to
polar, water soluble metabolites.
Trifluralii®
Trifluralii® , or treflan, is one of many dinitroaniline herbicides
which include Cobesffi), Nitralii® and Benefit®. These herbicides have
found extensive use in soybeans to control common annual grasses, pig-
weed and lambsquarters and are usually applied as either a preplant or
preemergence application. TrifluralirUv is best suited for soils with
3% organic matter or less (Wax, 1973). Extensive toxicological data
obtained on Trif luralirQy indicate a low order of acute toxicity, LD50
to rats of >10 g/kg, LC5Q of an emulsifiable concentrate to bluegills,
fathead minnows and goldfish of 0.58 ppm, 0.94 ppm and 0.59 ppm,
respectively (Parka and Worth, 1965).
The metabolism of TrifluralinD in plants, animals and soil as well as
photodecomposition has been investigated. In addition, the anaerobic
degradation of this herbicide has been examined. The pathways for
degradation of this herbicide have been the subject of an excellent
review (Probst and Tepe, 1969) and, therefore, will only be discussed
briefly. Degradation of Trif luraliiilP in the soil under aerobic con-
ditions leads to numerous products, including the mono- and di-
dealkylated derivatives of Trifluralin®, as well as mono- and di-
dealkylated TrifluralinIP with one of the 2,6-nitro groups reduced to an
amine. A final metabolite isolated from the aerobic system is the
conjugated a,Q!,Q!-trifluorotoluene-3,4,5-triamine.
The experiment with Trifluraliifiywas carried out twice employing
different modes of application. The normal-use pattern of Trifluralin®
is a soil treatment, so the analogous treatment in the model ecosystem
would be treatment of the sand at evenly spaced intervals (2.5 cm
apart) with 5 mg which corresponds to about 1 Ib/A. Since sorghum is
susceptible to Trif luraliiiB', a common variety of soybeans was grown in
place to establish the viability of the sand for plant growth. While
the Trifluraline) in this case was a sand treatment, no caterpillars
were added to act as the first stage of the food chain as well as a
dispersing agent. The sand treatment was then compared to the normal
47
-------
•p-
00
Table 28
Concentrations (ppm) of pyrazon and metabolites in organisms
in a model ecosystem
Compound
pyrazon
A
I^7
II
III
IV
V
Extractable ^C
Unextractable ^
Grand Total 14C
R -' Algae
0.63-0.69
0.47-0.51
0.40-0.43
0.23
0.16
0.10
0.00
0.0758
C 0.131
0.207
Clam Crab Daphnia Elodea Fish
0.476
_-
__
__
__
_.
0.0233
0.0498 0.499 0.0536 0.105 0.0336
0.0180 0.130 0.0455 0.0552 0.0237
0.0678 0.629 0.0991 0.160 0.0573
Mosquito Snail
__
__
--
__
__
--
__
0.175 0.127
0.148 0.0592
0.323 0.186
a/
— Silica Gel GF-254, benzene-ethanol, 60:40 by volume
—' Roman numerals - unknown spot
A 5-amino-4-chloro-3(2H)pyridazinone
-------
Table 29
Concentrations (ppm) of pyrazon and metabolites
in water in a model ecosystem
Compound
R
,' Unhydrolyzed Water
Hydrolyzed Water
pyrazon
A
it/
II
III
IV
V
Extractable ^C
Unextractable 14C
Grand Total 14C
0.63-0.69 0.0112
0.47-0.51
0.40-0.43
0.23
0.16
0.10
0.00 0.0000300
0.0112
0.0203
0.0315
0.00998
0.0000714
0.0000430
0.0000260
0.0000471
0.0000764
0.000106
0.0103
0.0105
0.0208
a/
—' Silica Gel GF-254, benzene-ethanol, 60:40 by volume
—' Roman numerals - unknown spots
A 5-amino-4-chloro-3(2H)pyridazinone
49
-------
sorghum* treatment which is the standard mode of application of
pesticides in the model ecosystem. The discussion of Trifluralii® will
then engender a comparison of the two methods of application and its
effect on the persistence and degradation pattern of this herbicide.
In Tables 30 and 32 are the data for the distribution of the metabo-
lites in the organisms of the sand- and sorghum-treated Trifluralii^
ecosystems. Several interesting differences are related to the two
treatments as the snail and fish contain more Trifluralin§) in the sand-
treated system than in the sorghum-treated system. This is shown by
the data which indicates that the snail and fish contained about 5.4x
and 3.Ox more herbicide in the sand experiment. Another striking
difference is the lack of algae in the sorghum treatment and the
existence of algae in the sand-treated ecosystem. The caterpillar,
which is the dispersing agent and the first member of the food chain,
apparently spread residues of Trifluralinfi) more efficiently into the
water which were phytotoxic and, therefore, inhibited the growth of
the algae in the sorghum treatment.
The data for the water portion of the model ecosystem (Tables 31 and
32) support the role of the caterpillar in spreading the TrifluralinS*
and metabolites in the system as the total radioactivity in the water
at the end of the experiment was about 6.4x greater in the sorghum-
treated ecosystem as compared with the sand-treated system. Apparently,
the TrifluralinB) is adsorbed on the sand and therefore does not
dissolve in the water. In contrast to the approximately 6-fold
difference in total radioactivitvin the water of the sorghum-treated
system, the amount of TrifluralinS' in the water is only 1.5x greater
in the sorghum treatment than in the sand treatment. Finally, the
concentration of TrifluralirtB) by the organisms appears to be affected
by the type of treatment as the values for accumulation of TrifluralinS'
over the concentration in the water by the fish and snail in the sand
treatment is 4,200x and 153,000x, respectively. In the sorghum treat-
ment the values for the fish and snail are 930x and 17,700x,
respectively. The caterpillar which degrades TrifluraliiQv in the
sorghum treatment, as well as the opportunity for TrifluralinS' to
undergo photodecomposition on the sorghum leaves before consumption by
the caterpillar, have a substantial effect on the persistence of this
herbicide as demonstrated by the accumulation factors for the snail
and fish. The accumulation factors of TrifluralinR for the fish and
snail are in the same order of magnitude as that obtained for
methoxychlor which was accumulated »vl,500x by the fish and about
123,000x by the snail (Metcalf et_ al., 1973). The snail is incapable
of degrading even the most biodegradable DDT analogue, methoxychlor,
as well as the herbicide, Trifluralin®.
50
-------
Table 30
Ul
Concentrations (ppm) of Trifluralii® and metabolites in organisms
in a model ecosystem after sorghum treatment
Compound
.Trifluralii®
1^
A
C
II
III
IV
E
V
VI
VII
VIII
Extractable l^C
Unextractable l^C
Grand Total ^C
Rf£' Daphnia
0.74
0.51
0.39
0.32
0.24
0.20
0.17
0.13
0.11
0.07
0.04
0.00
0.445
1.017
1.462
Fish Mosquito Snail
0.261 — 5.046
--
0.337
--
0.0399
0.216
--
--
--
0.228
__
0.506 — 0.796
0.767 0.238 6.535
1.011 0.520 6.648
1.777 0.758 13.183
-------
Table 30 (con't.)
I/
Silica Gel GF-254, hexane-acetone-MeOH, 90:10:2 by volume
— Roman numerals - unknown spots
A a,Q!jQ;-trif luoro-2 ,6-dinitro-N-propyl-£-toluidine
C 2,6-dinitro-4-trif luoroariilir.e
E 2-ethyl-5-trifluoromethyl-7-nitrobenzimidazole
-------
Table 31
Concentrations (ppm) of Trif luraliifD and metabolites
in water in a model ecosystem after sorghum treatment
Unhydrolyzed Water
Compound
Trifluralin®
I
A
C
II
III
IV
E
V
VI
VII
VIII
Extractable 14C
Unextractable ™
Grand Total
—' Silica Gel GF-254, hexane-acetone-MeOH, 90:10:2 by volume
—' Roman numerals - unknown spots
A a,0!,0!-trif luoro-2,6-dinitro-N-propyl-jD-toluidine
C 2,6-dinitro-4-trifluoroaniline
E 2-ethyl-5-tr if luommethyl-7-nitrobenzimidazole
Hydrolyzed Water
0.74
0.51
0.39
0.32
0.24
0.20
0.17
0.13
0.11
0.07
0.04
0.00
0.000282
0.000066
0.000087
0.000374
0.000322
0.000139
0.000315
0.000475
0.000415
0.000928
0.00123
0.00526
0.00989
0.0290
0.0388
—
--
--
--
--
--
0.000199
0.000328
0.000271
0.000486
0.000800
0.0116
0.0137
0.0253
0.0290
53
-------
Table 32
Ui
Concentrations (ppm) of Trif luralin® and metabolites in organisms
in a model ecosystem after sand treatment
Compound
Trifluralin®
&
A
B
D
E
V
Extractable l^C
Unextractable 14C
Grand Total 14C
RfS' Algae
0.74
0.61
0.56
0.36
0.22
0.09
0.00
0.350
0.475
0.825
Daphnia Fish
0.775
0.167
0.179
--
0.04
0.052
0.138
0.317 1.323
0.311 0.129
0.628 1.452
Mosquito Snail
27.085
0.667
__
0.323
__
__
0.766
0.208 28.870
0.168 0.183
0.376 29.053
£ Silica Gel GF-254, hexane-acetone-MeOH, 90:10:2 by volume
£/ Roman numerals - unknown spots
A a,a,Q;-trifluoro-2,6-dinitro-N-propyl-£-toluidine
B N,N-dipropyl-3-nitro-5-trifluoromethyl-£-phenylenediamine
D 2-ethyl-5-trifluoromethyl-7-nitro-l-propylbenimidazole
E 2-ethyl-5-trifluoromethyl-7-nitrobenzimidazole
-------
Table 33
Concentrations (ppm) of TrifluralinS) and metabolites
in water in a model ecosystem after sand treatment
Compound
Tr£fluralin5)
iV
A
II
B
C
D
III
E
IV
V
Extractable ^C
Unextractable ^C
Grand Total ^C
R a/
Rf~
0.74
0.61
0.56
0.48
0.36
0.27
0.22
0.14
0.09
0.05
0.00
Unhydrolyzed Water
0.000184
0.0000343
—
--
--
0.000140
0.0000917
0.000111
0.000414
0.000597
0.00144
0.00301
0.00383
0.00684
Hydro ly zed Water
--
--
0.0000104
--
--
--
--
0.000017
0.0000737
0.000299
0.000687
0.00109
0.00274
0.00383
2. Silica Gel GF-254, hexane-acetone-MeOH, 90:10:2 by volume
—' Roman numerals - unknown spots
A 0!,a,Q!-trif luoro-2,6-dinitro-IJ-propyl-j>-toluidine
B N,N-dipropyl-3-nitro-5-trifluoromethyl-£-phenylenediamine
D 2-ethyl-5-trifluoromethyl-7-nitro-l-propylbenimidazole
E 2-ethyl-5-trifluoromethyl-7-nitrobenzimidazole
55
-------
SECTION V
EXAMINATION OF A MITICIDE, SELECT PLASTICIZERS,
A FUNGICIDE AND A BACTERIOSTAT
The final segment of this report of the fate of select pesticides in
the aquatic environment deals with a miticide, two types of plasti-
cizerSj a fungicide and a bacteriostat. The miticide was chosen as
little environmental information is known about acaricides in general
and further, this is a new class of miticide which has not yet found
generalized use. Therefore, it would be of interest to examine the
persistence and uptake of this pesticide by the organisms of the model
ecosystem before it is used in large quantities in the environment.
Two types of plasticizers were examined in the model ecosystem because
they have been demonstrated to be pollutants of fish, birds and many
other forms of wildlife. In contrast to the previously discussed
pesticides, these compounds were not purposefully applied to control a
pest, but have become pollutants unintentionally as the result of
either industrial discharge during production or from seepage into the
environment during their intended use. The high lipid solubility,
inertness to chemical and biological degradation, particularly for the
higher chlorinated PCB's, and coupled with their multibillion pound
production clearly explains the worldwide occurrence of these materials
in the environment.
The examination of captan in the model ecosystem was important for two
reasons. First, the use of fungicides containing mercury is now
generally considered to be both environmentally unsafe as well as
hazardous to human health. The mercury fungicides are quite toxic to
humans and can cause severe poisoning when ingested. Some adults and
children in New Mexico and Iran mistakenly utilized grain treated with
mercury fungicides for feed for swine and for making bread and, as a
result, they suffered from acute mercury posioning. Secondly, captan
has been used for about 20 years without apparent environmental prob-
lems related to persistence and food web magnification. In order to
validate the use of the model ecosystem as a useful tool for prediction
of pesticide persistence in food chain accumulation, it is necessary to
examine compounds, such as captan, which have had little environmental
impact after widespread use, as well as persistent compounds, such as
dieldrin, DDT or aldrin. If both ends of the persistence spectrum do
not agree both in the field and the model ecosystem, then this system
would be of little value as a predictive tool for new pesticides.
Banomite®
Banomite® is a new class of miticidal benzoyl chloride phenylhydrazines
which is being developed for the control of mites which attack citrus
(Kaugers ejt al. , 1973: Moon et al., 1972). Since these are a new class
of acaricides, environmental information or metabolism data on these
compounds has not been published.
56
-------
The data contained in Table 34 describe the distribution of BanomiteS'
and its degradation products in the organisms of the model ecosystem.
Three of the organisms contain small residues of Banomitely, in particu-
lar the crab, 0.0156 ppm; Elodea, 0.041 ppm and the mosquito larvae
with 0.0736 ppm. The only other metabolism or degradation product
ffiat could be identified in the organisms is the hydrolysis product of
BanomiteJy, benzoic acid 2,4,6-trichlorohydrazide. The algae, crab,
Elodea, mosquito and snail contained 0.142 ppm, 0.0364 ppm, 0.0515 ppm,
0.300 ppm and 0.306 ppm, respectively, of this metabolite. In addition
to the two identified compounds, there were eight other unidentified
metabolites. This acaricide is labile and undergoes degradation to the
numerous metabolites isolated from the organisms. The snail and fish
contain considerable amounts of unidentified Metabolite II with 10.69
ppm and 1.62 ppm, respectively.
Examination of the data for the water (Table 35) for BanomiteB) shows a
similar distribution of Banomite*' and degradation products. Therewere
small amounts of the two characterized compounds, namely, Banomite**'at •
18.62 ppt and benzoic acid 2,4,6-trichlorophenylhydrazide at 294 ppt.
The value for the water concentration of BanomiteB', when divided into
those organisms which contained this miticide, reveal that the crab,
Elodea and mosquito accumulated Banomite® from the water 840x, 2,200x
and 4,000x, respectively. The other degradation product, or metabolite
which was found in the organisms, benzoic acid 2,4,6-
trichlorophenylhydrazide, was accumulated from the water by the algae,
crab, Elodea, mosquito and snail 500x, 125x, 175x, l,000x and l,000x,
respectively. However, the unidentified Metabolite II was accumulated
from the water by the fish 3,000x and the snail o/19,000x, and therefore
its structure should be investigated further to determine if this
metabolite has any physiological effect at this level.
Di-n-octyl phthalate (DOP)
The concern for environmental quality has stimulated interest in the
disposition of substances which interfere with residue analysis, such
as the polychlorinated biphenyls (PCB's) and the phthalate ester plasti-
cizers. The latter are produced in enormous quantities, for example,
some 4.5 x 10? Ibs in 1972 {Anon. 1972). The phthalate esters, which
as pollutants occur in fish taken from streams and rivers in the United
States (Mayer et al., 1972), appear to have a low order of acute
toxicity to aquatic organisms (Sanders et al., 1973); but, for instance,
di-2-ethylhexyl phthalate, the largest produced phthalate plasticizer,
accumulates in snails, mosquito larvae and mosquito fish in a model
ecosystem experiment (Metcalf et _al., 1973). Therefore, to establish
the relationship between plasticizer chemical structure and environ-
mental persistence, di-n-octyl phthalate was examined in the model
ecosystem.
Previous model ecosystem studies with di-2-ethylhexyl phthalate (DEHP)
demonstrated that this phthalate ester was degraded to mono
2-ethylhexyl phthalate and phthalic acid (Metcalf et_ al., 1973). Only
57
-------
00
Table 34
Concentrations (ppm) of BanomiteQy and metabolites in
in a model ecosystem
organisms
Compound
Banomite®
&
II
III
A
IV
V
VI
VII
VIII
Extractable 14C
Unextractable 14(
Grand Total 14C
R
0
0
0
0
0
0
0
0
0
0
-
1
J
.£='
.75
.61
.53
.35
.27
.21
.14
.07
.03
.00
Algae
--
--
0.963
0.181
0.142
0.202
0.269
--
0.514
0.923
3.191
6.602
9.793
Clam
0
--
2.044 0
0
0
—
0.227 0
--
0
0.0703 1
2 . 342 1
0.136 1
2.478 2
Crab Daphnia
.0156
__
.0670 0.686
.0568
.0364
__
.0406
—
.140
.00850 0.255
.366 0.941
.0878 0.877
.454 1.818
Elodea
0
0
1
0
0
0
0
0
1
1
3
.0410
.0928
.048
.0662
.0515
--
.185
--
.059
.328
.874
.445
.319
1
0
0
0
0
2
0
2
Fish
--
--
.624
.378
--
--
.0943
.0452
--
.180
.323
.451
.774
Mosquito
0.0736
0.266
0.453
0.265
0.300
--
0.324
0.286
0.533
1.652
4.156
2.137
6.293
Snail
--
0:565
10.685
1.160
0.306
--
2.549
0.938
0.478
0.872
17.542
1.777
19.319
£ Silica Gel GF-254, n-hexane-ethyl acetate, 80:20 by volume
—' Roman numerals - unknown spots
A benzoic acid 2,4,6-trichlorophenyl hydrazide
-------
Table 35
Concentrations (ppm) of Banomite® and metabolites
in water in a model ecosystem
Compound
a/
Unhydrolyzed Water
Hydrolyzed Water
Banomite®
£/
II
III
A
IV
V
VI
VII
VIII
Extractable ^C
Unextractable l^C
Grand Total 14C
0.75
0.61
0.53
0.35
0.27
0.21
0.14
0.07
0.03
0.00
0.00000892
0.0000602
0.000444
0.000452
0.000141
0.000110
0.000693
0.00180
0.000662
0.00176
0.00612
0.0243
0.0304
0.0000097
0.0000328
0.0000948
0.000688
0.000153
0.000184
0.00157
0.000682
0.00362
0.0093
0.0164
0.00599
0.0224
—' Silica Gel GF-254, n-hexane-ethyl acetate, 80:20 by volume
—' Roman numerals - unknown spots
A benzoic acid-2,4,6-trichlorophenyl hydrazide
59
-------
the mosquito larvae, snail and mosquito fish accumulated from the water
DEHP 100,000x, 21,000x and 130x, respectively.
The data for the distribution of DOP in the organisms of the model
ecosystem are collected in Table 36. The algae contained the most DOP
at 1.80 ppm, the snail with the next highest at 0.85 ppm, the fish and
mosquito at 0.59 ppm and Daphnia at 0.16 ppm. In addition to DOP there
were about six unidentified metabolites, but no mono octyl phthalate
was isolated from any of the organisms. In all cases, except the fish,
most of the radioactivity averaged about 75% unextractable, whereas the
fish had only about 22% unextractable. Perhaps the low titer of liver
microsomal enzymes in Gambusia affinis (Krieger and Lee, 1973) accounts
for the inability of the fish to convert DOP to polar unextractable
products.
The water portion of this model ecosystem experiment as indicated in
Table 37 contained small amounts of DOP, 6.3 ppt, no mono octyl
phthalate and small amounts of phthalic acid, 0.782-1.82 ppb. Using
the values obtained for the amounts of DOP in the water and organisms,
concentration factors can be calculated for algae 28,500x, Daphnia
2,600x, fish and mosquito larvae 9,400x and 13,600x for the snail.
Previous ecosystem evaluation of the branched DEHP indicated that this
plasticizer was accumulated from the water by the snail 21,000x, the
mosquito fish 130x and the mosquito larvae 100,000x. With only two
esters examined in this model ecosystem, it is difficult to account for
the differences in the uptake of these structurally related plasticizers,
It is obvious that despite the susceptibility of these two plasticizers
to undergo substantial degradation, their high lipid solubility
accounts for their uptake and storage in the organisms of this model
ecosystem (Mayer et al., 1972).
Polychlorinated Biphenyls
The ubiquitous occurrence of polychlorinated biphenyls (PCB's) in the
environment has been well reviewed (Peakall, 1972) and, therefore, a
few brief comments will be made about their chemical and environmental
properties. The industrial PCB's are a complex mixture of chlorinated
biphenyls which have a multitude of uses including heat-transfer fluids,
plasticizers and extenders for pesticides. The inert chemical proper-
ties of these compounds make them excellent in their numerous
applications, but, because of their environmental stability and high
lipid solubility, they have been found in the lipoidal tissues of
numerous animals, principally in fish (Henderson, 1971) and birds
(Risebrough, 1969). The primary production of polychlorinated
biphenyls in the United States is by the Monsanto Company under the
trade name Aroclor© 1254, 1242, 1221, etc., where the first two digits
identify it as a derivative of biphenyl which has 12 carbons and the
last two digits relate to the average percent chlorine, i.e., 1254 has
54% chlorine.
60
-------
Table 36
Concentrations (ppm) of di-ri-octyl phthalate and metabolites
in organisms of a model ecosystem
Compound
DOP
&
II
III
IV
VI
VII
Extractable 14C
Unextractable ^C
Grand Total 14C
R a/
0.92
0.73
0.53
0.47
0.35
0.25
0.00
Algae
1.7963
0.6709
0.3356
0.3797
0.0808
--
7.3654
10.6348
43.2011
53.8359
Daphnia
0.1645
--
0.1425
0.1722
--
--
1.2001
1.6793
7.4703
9.1488
Fish
0.5920
--
0.0357
0.0374
--
--
0.2649
0.9300
0.3974
1.3273
Mosquito
0.5925
0.1748
0.4855
0.1641
0.0906
--
0.3314
1.8389
6.7225
8.5614
Snail
0.8543
0.0545
0.1643
0.1477
--
0.0569
0.2882
1.5659
2.9077
4.4736
^•'l Silica Gel GF-254, benzene-acetone-petroleum ether-acetic acid, 50:5:25:1 by volume
— Roman numerals, unknown spots
-------
Table 37
Concentrations (ppm) of di-ja-octyl phthalate and metabolites
in organisms of a model ecosystem
Compound
Unhydrolyzed Water
Hydrolyzed Water
DOP
1^
II
III
IV
V
VI
phthalic acid
VII
Extract able ^C
Unextractable 1
-------
The initial studies with the PCB's and animals were carried out with
the complex mixtures which make analysis of the metabolites and change
in the constitution of the PCB mixture very difficult. However, with
the recent availability of pure 14-C isomers of three of the PCB's, more
pr.e^ise studies on the uptake and metabolism of PCB's can be undertaken.
The three labeled PCB's currently available from the Mallinckrodt
Chemical Company are 2 ,5,2'-trichlorobiphenyl, 2,5,2',5'-
tetrachlorobiphenyl and 2,4,5,2',5'-pentachlorobiphenyl. Through the
cooperation of Professor Robert L. Metcalf, University of Illinois, it
was possible that these compounds could be obtained for model ecosystem
studies in his laboratory.
The data in Table 38 contain the distribution in both the water and
organisms for the three pure isomer l^C PCB's. An interesting aspect of
the data is the gradual increase in concentration of the three com-
pounds as the chlorine number is increased from three to five. For
example, the fish contains 1.28 ppm trichlorobiphenyl, 14.24 ppm
tetrachlorobiphenyl and 119.71 ppm pentachlorobiphenyl. For the snail
the increased accumulation of the biphenyls is similar to the fish, but
the levels are higher as 18.97 ppm trichlorobiphenyl, 47.33 ppm tetra-
chlorobiphenyl and 587.35 ppm for pentachlorobiphenyl were isolated
from this organism.
Another significant aspect of the data is the gradual decrease in
percent unextractable radioactivity in the fish as the number of
chlorine substituents is increased from three to five. The percentage
values for the unextractable radioactivity are 15% for the trichloro-
biphenyl, 2.44% for the tetrachlorobiphenyl and 1.10% for the
pentachlorobiphenyl, which indicates the relative susceptibility of
these three compounds to undergo metabolism by the fish.
One last comment regards the relative accumulation from the water of
these PCB's by the snail and fish. The fish accumulated the 3-, 4- and
5-chlorinated biphenyls 6,400x, ll,863x and 12,153x, respectively, the
concentration in the water. The snail showed a greater differential
between the numbers of chlorine substituents and accumulation values as
the 3-, 4- and 5-chlorinated biphenyls accumulated 5,795x, 39,439x and
59,629x, respectively, the water concentration. This differential
between accumulation factors for the snail as compared to the fish may
reflect the greater metabolic capacity of the fish to transform these
lipid soluble compounds to water soluble compounds after they are taken
up from their environment.
Captan
This nonmercury fungicide is widely employed as an effective agent for
the control of fungus in vegetables, fruits and ornamentals. In
addition, it is utilized as an effective seed treatment. The safety of
this fungicide to rats is demonstrated by its oral LD5Q of >15,000
mg/kg and an intravenous 11)50 of 50-100 mg/kg (Metcalf, 1971). Feeding
studies conducted with captan for a 2-year period at 10,000 ppm with
63
-------
Table 38
Distribution of chlorinated biphenyls and their
degradation products in the model ecosystem
I. 2,5,2'-trichlorobiphenyl
total 1*C
Unknown I (Rf 0.66*)
trichlorobiphenyl (Rf 0.56)
Unknown II (Rf 0.23)
Unknown III (Rf 0.10)
Unknown IV (Rf 0.06)
Unknown V (Rf 0.04)
Unknown VI (Rf 0.03)
Polar (Rf 0.0)
Unextractable
chlorinated biphenyl equivalents - ppm
H20
0.03845
0.00015
0.00020
0.00005
--
0.00055
0.00040
0.00040
0.02265
0.01405
Oedoeonium
(alea)
23.2155
15.9575
1.4630
0.0520
~-
--
--
0.0685
0.5185
5.1560
Physa
(snail)
31.2015
18.9720
1.1590
0.6480
0.9735
0.5460
0.2205
0.4410
3.9315
4.3100
Culex
(mosquito)
2 . 7030
1.1995
0.1630
—
--
--
--
--
0.4795
0.8610
Gambus ia
(fish)
3.2055
0.2085
1.2800
0.1595
--
--
--
--
0.9985
0.5590
-------
Table 38 (con't.)
Oi
II. 2,5,2' ,5'-tetrachlorobiphenyl
total 14C
tetrachlorobiphenyl (Rf 0.48*)
Unknown I (Rf 0.23)
Unknown II (Rf 0.04)
Polar (Rf 0.0)
Unextractable
III. 2, 5,2', 4', 5'-
pentachlorobiphenyl
total 14C
pentachlorobiphenyl (Rf 0.55*)
Unknown I (Rf 0.46)
Unknown II (Rf 0.39)
Unknown III (Rf 0.21)
Unknown IV (Rf 0.04)
Unknown V (Rf 0.02)
H2°
0.02065
0.00120
0.00005
0.00155
0.01225
0.00560
0 . 04340
0.00985
--
0.00020
0.00015
0.00030
0.00385
Oedogonium
(alga)
23.6845
21.5975
0.3220
0.1030
0.3275
1.3345
62.4660
53.8440
0.6850
0.5080
0.1425
--
0.2570
Physa
(snail)
53.7465
47.3275
0.7560
0.4360
3.9850
1.2420
633.0165
587.3545
8.6210
2.2490
1.9365
0.5000
7.4965
Culex
(mosquito)
14.5335
12.6745
0.1070
--
0.9670
0.7850
181.4565
170.8480
2.4070
1.3195
1.0520
--
_ _
Gambusia
(fish)
15.5685
14.2360
0.0890
--
0 . 8545
0.3900
127.6945
119.7060
2.5380
0.5810
0.3285
--
0.7450
-------
Table 38 (con't.)
Polar (Rf 0.0)
Unextractable
H2°
0.02055
0.00850
Oedogonium
(alga)
1.6265
5.4330
Physa
(snail)
16.5550
8.3040
Culex
(mosquito)
2.6745
3.1555
Gambusia
(fish)
2.3610
1.4350
*TLC with hexane (Skelly solve B b.p. 60-68°C)
-------
rats showed no adverse effects. The mode of action of this compound
is not clear as early work by Kittleson in 1952 suggests that the
activity of this compound was related to the presence of the trichloro-
methyl group. Later (Rich, 1960), the fungicidal activity was ascribed
to-tfte production of thiophosgene after the displacement of the
trichloromethyl group by a mercaptan group.
There appears to be some information about the environmental stability
of captan. The water solubility is reported to be less than 10 ppm and
undergoes hydrolysis in water of pH 7.0. In addition, the trichloro-
methyl sulfur moiety reacts readily with free thiol groups in
biological systems (Lukens, 1969). The degradation in soil appears to
proceed via hydrolysis with soil microorganisms playing a significant
role (Lukens, 1969). The half-life in a moist, silt soil is about 3-4
days and much longer in an air-dried soil (Burchfield, 1959) . The
structures of the metabolites in soil are not completely known,
although the existence of carbonyl sulfide as a product has been
demonstrated (Somers e_t a±., 1967).
The behavior of captan in this terrestrial-aquatic model ecosystem
corroborates the previous data obtained from field experiments as none
of the organisms after 33 days contained residues of this fungicide
(Table 39). In view of the alkaline pH of the aqueous portion of the
system, the captan undoubtedly under went hydrolysis as soon as it came
in contact with the water. There were small amounts of unidentifiable
residues in the snail, fish and algae, but no captan, which had an Rf
of 0.3, was isolated from the organisms. The interesting aspect of the
metabolites isolated from the snail was that they were much less polar
than captan. Since the label was located on the trichloromethyl moiety,
perhaps the three spots are the result of a disulfide exchange with
captan and another mercaptan.
The water portion of the model ecosystem (Table 40) does not contain
any traces of captan nor any of the nonpolar metabolites found in
either the algae or snail. Again as demonstrated for the organisms,
captan does not persist in the water as there were only metabolites which
had Rf values less than 0.35. It appears that continued use of captan
will not have any serious environmental impact as it does not persist
in the water of this 33-day model ecosystem, nor does it accumulate in
the fish which is the upper member of the food chain. The probable
reason for the nonpersistence of this fungicide in this model ecosystem
is the extremely labile trichloromethyl sulfur-nitrogen bond which can
be split either by hydrolysis or reaction with mercaptan groups in
biological systems.
Hexachlorophene
The final compound to be examined in the model ecosystem is the
bacteriostat, hexachlorophene. The use of this antibacterial agent
has been restricted because of the reported poisonings in France from
baby powder that contained this compound. Almost nothing is known about
67
-------
CX5
Table 39
Concentrations (ppm) of Captan and metabolites
in organisms in a model ecosystem
Compound
iV
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
XIII
XIV
XV
R£a
0.93
0.85
0.81
0.79
0.68
0.39
0.35
0.33
0.26
0.25
0.18
0.14
0.10
0.053
0.00
Algae Daphnia Fish
0.0278
0.0077
__
0.0166
0.0492
0.0105
__
0.0142
__
0.00608
__
__
' 0.0590
0.0159 — 0.00215
0.122 — 0.000861
Mosquito Snail
0.0592
0.0795
0.0679
__
__
__
__
__
__
--
--
_-
_-
__
0.00941
-------
Table 39 (con't.) t
Compound Rf^' Algae Daphnia Fish Mosquito Snail
Extractable ^C . 0.280 0.393 0.0522 0.0462 0.216
Unextractable 14C 0.967 0.338 0.0158 0.0584 0.0998
Grand Total 1(^C 1.247 0.731 0.0680 0.105 0.316
a/
—' Silica Gel GF-254, petroleum ether-acetone, 4:1 by volume
]*.' Roman numerals - unknown spots
VO
-------
Table 40
Concentrations (ppm) of Captan and metabolites
in water in a model ecosystem
Compound
i*/
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
XIII
XIV
XV
Extractable 14C
Unextractable ^C
Grand Total 14C
«**'
0.93
0.85
0.81
0.79
0.68
0.39
0.35
0.33
0.26
0.25
0.18
0.14
0.10
0.053
0.00
Unhydrolyzed Water
--
--
--
--
--
--
0.00000426
--
0.00000960
--
0.00000456
0.00000273
0.00000365
0.0000648
0.00000761
0.0000971
0.000846
0.000943
Hydro lyzed Water
--
--
--
--
--
--
--
--
--
0.00000893
--
0.00000812
--
0.0000243
0.0000277
0.0000691
0.000777
0.000846
£/ Silica Gel GF-254, petroleum ether-acetone, 4:1 by volume
_' Roman numerals - unknown spots
70
-------
this bisphenol and its metabolic products, though studies with rats
(Wit and Van Genderen, 1962) and cows (St. John and Lisk, 1972) have
demonstrated that the majority of the hexachlorophene is excreted
unchanged in the urine and feces when fed to these animals. However,
no-attempt was made to identify any of the metabolites. While some
work has been carried out on the metabolism of this compound in animals,
nothing is known about the environmental fate of this material except
that it is thought to persist in surface waters for long periods of
time without undergoing substantial degradation (Bandt and Nehring,
1962). Recently, hexachlorophene (HCP) has been detected in sewer
influents in Oregon at levels of 20-31 ppb and in river water upstream
from the city of Corvallis, Oregon, at 0.01-0.10 ppb. Sewer treatment
of the influent removed about 60-70% of the HCP (Buhler et: al^. , 1973).
In view of the mammalian toxicity of hexachlorophene (Nakaue et al.,
1973) and the dearth of environmental degradation information, it is
imperative to carry out some preliminary studies on the fate of HCP in
this model ecosystem.
The data for the fate of HCP in the organisms and water of this model
ecosystem are contained in Tables 41 and 42. The first aspect noticed
is the absence of Daphnia and mosquito larvae from the table. This
indicates that these organians did not contain sufficient radioactivity
to be chromatographed. Three of the organisms, algae, 1.99 ppm; fish,
0.37 ppm; and snail, 1.31 ppm contained identifiable amounts of
hexachlorophene along with several other uncharacterized metabolites.
Hexachlorophene represented about 42.8% of the total radioactivity in
the algae, 18.3% in the fish and 17.4% in the snail. The rest of the
radioactivity in these organisms was distributed among ten uncharac-
terized metabolites. While there were a substantial number of
metabolites in the three organisms, the unextractable radioactivity was
highest for the snail, 38%, intermediate for the algae, 25% and lowest
for the fish, 5.5%.
The water portion of the model ecosystem has small amounts of HCP,
0.00134 ppm, as well as numerous uncharacterized metabolites. If the
figure for the hexachlorophene concentration in the water, 0.00134 ppm,
is divided into the concentrations of HCP in the various organisms,
concentration factors for the algae, l,500x; fish, 278x; and snail,
970x are derived. It can be concluded that the uptake of hexachloro-
phene by the fish is similar to that found for parathion, which had a
concentration factor of about 335x. Finally, the unextractable radio-
activity in the water amounts to about 36%, which indicates that
hexachlorophene is not extensively degraded to polar, unextractable
metabolites either by the organisms or chemical factors, such as
hydrolysis or photolysis. The inert nature of hexachlorophene is
related to its polar nature resultant from the two hydroxyl groups and
the highly substituted aromatic ring with chlorine and a methylene
bridge. Higher chlorinated phenols such as 2,4,5-trichlorophenol and
2,3,4,6-tetrachlorophenol require about 10 weeks to undergo ring
cleavage in soil (Alexander, 1972). The 2,3,4,6-tetrachlorophenol is
71
-------
precisely the same arrangement of substituents of hexachlorophene,
except the two position of HCP is filled by a methylene bridge instead
of a halogen.
72
-------
Table 41
Concentrations (ppm) of hexachlorophene and
metabolites in organisms in a model ecosystem
Compound
hexachlorophene
£/
II
III
IV
V
VI
VII
VIII
IX
Extractable 14C
Unextractable 14C
Grand Total 14C
RfS/
0.89
0.82
0.75
0.70
0.65
0.53
0.23
0.14
0.07
0.00
Algae
1.994
0.608
--
--
--
0.563
0.0451
0.259
--
--
3.469
«
1.195
4.664
Fish
0.371
1.233
--
--
--
--
0.151
0.0261
0.0810
--
1.861
0.109
1.970
Snail
1.309
--
--
--
2.182
--
0.638
--
--
0.638
4.767
2.893
7.650
y Silica Gel GF-254, benzene-methanol-acetic acid, 45:8:4 by volume
—' Roman numerals - unknown spots
73
-------
Table 42
Concentrations (ppm) of hexachlorophene
and metabolites in water in a model ecosystem
Compound
Unhydrolyzed Water
Hydrolyzed Water
hexachlorophene
£/
II
III
IV
V
VI
VII
VIII
IX
Extractable 14C
Unextractable ^C
Grand Total 14C
0.89
0.82
0.75
0.70
0.65
0.53
0.23
0.14
0.07
0.00
0.000542
--
0.00120
--
0.00183
0.000132
0.0000696
--
--
0.00000794
0.00378
0.03080
0.03458
0.000798
0.000444
0.00130
0.00374
0.00609
0.000536
0.00384
0.000542
--
0.000238
0.01753
0.00556
0.02309
— Silica Gel GF-254, benzene-methanol-acetic acid, 45:8:4 by volume
b/ Roman numerals - unknown spots
74
-------
Table 43
Accumulation factors for fish and snail for compounds
examined in the model ecosystem*
Insecticides
BuxR
SevinR
carbofuran
dieldrin
OrtheneR
parathion
lindane and Aroclor 5460R
Herbicides
alachlor
propachlor
BladexR
BentazonR
dicamba
2,4-D
pyrazon
TrifluralinR (sorghum treatment)
TrifluralinR (sand treafment)
Others
2,5,2'-trichlorobiphenyl
2,5,2l}5'-tetrachlorobiphenyl
2,4,5,2',5'-pentachlorobiphenyl
di-n-octyl phthalate
hexachlorophene
captan
BanomiteR
Fish
Snail
335
2,110
452
930
4,200
6,400
11,863
12,153
9,400
278
17,700
153,000
5,795
39,439
59,629
13,600
970
*Accumulation factor equal concentration of chemical (ppm) in the
organism/concentration of chemical (ppm) in the water
75
-------
SECTION VI
REFERENCES
Abernathy, John R., and L. M. Wax. Weed Sci. ^1:224, 1973.
Alexander, M. In: Environmental Toxicology of Pesticides,
Matsumura, Fumio, G. Mallory Boush, and Tomomasa Mi sato (eds.).
New York, Academic Press, 1972. p. 365.
Anon. Chem. Eng. News. 51 (23):13, 1973.
Anon. Herbicide Handbook. Geneva, New York, The W. F. Humphrey
Press, Inc., 1970. p. 5.
Bandt, H. J., and D. Nehring. Z. Fisch. 10:543, 1962.
Beynon, K. I., G. Stoydin, and A. N. Wright. Pest. Sci. _3:379,
1972.
Broadhurst, N. A., M. L. Montgomery, and V. H. Freed. J. Agr. Food
Chem. _14:585, 1966.
Buhler, Donald R., M. E. Rasmusson, and H. S. Nakaue. Environ.
Sci. Technol. 7_:929, 1973.
Burchfield, H. P. Contrib. Boyce Thompson Inst. 20:205, 1959.
Chevron Chemical Company. Technical Bulletin. 1972.
Childers, W. F., and W. N. Bruce. Unpublished data. 1973.
Dhillion, Nirmal S. Dist. Abstra. Int. B. _31:7136, 1971.
Frank, Richard. Dist. Abstr. Int. B. _32:4444, 1972.
Friesen, H. A. Weeds. J.3:30, 1965.
Fukuto, T. Roy, and James J. Sims. In: Pesticides in the Environment,
White-Stevens, Robert (ed.). New York, Marcel Dekker, Inc., 1971.
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Grover, P. L., and P. Sims. Biochem. J. 96:521, 1965.
Gunther, F. A., W. Westlake, and P. S. Jaglan. Residue Reviews.
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Hargrove, R. S., and M. G. Merkle. Weed Sci. 1.9:652, 1971.
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Herbicide Handbook. Geneva, New York, The W. F. Humphrey Press,
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Horstein, I., and W. N. Sullivan. J. Econ. Ent. 46:937, 1953.
Hurtig, Henry. In: Environmental Toxicology of Pesticides,
Matsumura, Fumio, G. Mallory Boush, and Tomomasa Misato (eds.).
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Hutson, D. H., M. H. Hoadley, M. H. Griffiths, and C. Donninger.
J. Agr. Food Chem. IS-.507, 1970.
Kaugars, Girts, Edwin G. Gemrich, and Victor L. Rizzo. J. Agr.
Food Chem. 21:647, 1973.
Kittleson, A. Science. 115:84, 1952.
Knaak, James B. Bull. Wld. Hlth. Org. 44:121, 1971.
Krieger, R. I., and P. W. Lee. Arch. Environ. Cont. Tox. J.:112,
1973.
Ruhlman, D. E. In: Twenty-fifth Illinois Custom Spray Operators
Training School, 1973. p. 149.
Kuhlman, D. E.., and T. A. Cooley. In: Twenty-fifth Illinois Custom
Spray Operators Training School, 1973. p. 170.
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Metcalf, Robert L. In: Pesticides in the Environment, White-
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Tsao, Ching-Hsi, W. N. Sullivan, and Irwin Horstein. J. Econ. Ent.
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11:123, 1962.
79
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SECTION VII
PUBLICATIONS
Booth, Gary M., John Connor, R. A. Metcalf and J. R. Larsen. 1973.
A comparative study of the effects of selective inhibitors on
esterase isozymes from the mosquito Anopheles punctipennis. Comp.
Biochem. Physiol., 44B: 1185-1195.
Sanborn, James R. and Ching-Chieh Yu. 1973. The fate of dieldrin in
a model ecosystem. Bull. Environ. Contain. Toxicol., 10, 340.
Cho, P., R. Davenport, G. S. Whitt, G. M. Booth and J. R. Larsen. 1972.
Electrophoretic and histochemical analysis of esterase synthesis in
the ovariole of the milkweed bug Oncopeltus fasciatus (Dall.).
Wilhelm Roux1 Archiv., 170: 209-220.
Booth, Gary M. and Robert L. Metcalf. 1972. The histochemical fate
of paraoxon in the cockroach (Periplaneta americana) and honey bee
(Apis mellifera) brain. Israel Journal of Entomology VII: 143-156.
Bruce, W. N. 1972. Separation and identification of carbpfuran, its
metabolites, and conjugates found in fish exposed to ring l^C-labeled
carbofuran using ITLC silica gel strips. J. Econ. Entomol. 65(6);
1738-1740.
Yu, Ching-Chieh, Robert L. Metcalf and Gary M Booth. 1972. Inhibi-
tion of acetylcholinesterase from mammals and insects by carbofuran
and its related compounds and their toxicities toward these animals.
Agr. and Food Chem., 20(5): 923-926,
In Preparation
Yu, Ching-Chieh and James R. Sanborn. The fate of parathion in a
model ecosystem. To be submitted to Bull. Environ. Contam. Toxicol.
Sanborn, James R., Robert L. Metcalf and William F. Childers. The
uptake of three PCB's, DDT and DDE by the green sun fish Lepomis
cyanellus Raf. To be submitted to Bull. Environ. Contam. Toxicol.
Sanborn, James R., Robert L. Metcalf, Ching-Chieh Yu and Po-Yung Lu.
Plasticizers in the environment. The fate of di-n-octyl phthalate
(DOP) in two model ecosystems and uptake and metabolism of DOP by
aquatic organisms. To be submitted to Arch. Environ. Contam. Toxicol.
Sanborn, James R. and Ching-Chieh Yu. The fate of TreflaiiB) in a model
ecosystem: A comparison of two methods of treatment. To be submitted
to Bull. Environ. Contam. Toxicol.
80
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Metcalf, Robert L., James R. Sanborn, Po-Yung Lu and Donald E. Nye.
Laboratory model ecosystem studies of degradation and fate of radio-
labeled tri-, tetra-, and pentachlorobiphenyl compared with DDE. To
be submitted to Arch. Environ. Cont. Toxicol.
81
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CHEMICAL NOMENCLATURE
Compound
Sevii®
car bo fur an
dieldrin
lindane
Orthene®
parathion
alachlor
propachlor
BladeJ)
Bentazori®
dicamba
2,4-D
Pyrazon®
TrifluralinR
Banomite®
trichlorobiphenyl
tetrachlorobiphenyl
pentachlorobiphenyl
SECTION VIII
FOR COMPOUNDS EXAMINED IN A MODEL ECOSYSTEM
Name
3:1 mixture of m-(l-ethylpropyl)phenyl N-
methylcarbamate and m-(l-methylbutyl)phenyl N-
methylcarbamate
1-napthyl N-methylcarbamate
2,2-dimethyl-2,3-dihydrobenzofuranyl 7-N-
methylcarbamate
1,2,3,4,10,10-hexachloro-6,7-epoxy-l,4,4a,5,
6,7,8a-octahy_
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Compound Name
DOP di-n-octyl phthalate
captan N-trichloromethylthio-4-cyclohexene-l,2-
dicarboximide
hexachlorophene 2,2-methylene-bis (3,4,6-trichlorophenol)
83
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
rt No.
4. Title
FATE QF SELECT PESTICIDES IN THE
AQUATIC ENVIRONMENT
7. Author(3) sanborn, James R.
9. Organization Illinois Natural History Survey and
Board of Trustees, University of Illinois,
Urbana, Illinois
J2. Sponsoring Ore*™* ion ENVIRONMENTAL PROTECTION AGENCY
3.
ioz No,
w
5. l
6. '
8. Performing Otg*a
Report No,
if). Project No.
R-800736
i. Contrac':jGrantNo
Grant R-800736
13. Type of Repor: and
Period Covered Final
15.
16. Abstract
In this study 17 organic pesticides and five industrial chemicals were examined in a
terrestrial-aquatic model ecosystem in an effort to determine their persistence and
accumulation by the organisms of this system. Several classes of pesticides are
represented as one or more insecticides, herbicides, miticides or plasticizers were
investigated in this system. The use of this system for examining uptake and per-
sistence of widely used agricultural chemicals provides the necessary data for compari-
son of field data to provide a framework which can be used to assess the potential
environmental impact of new pesticides before they are given a recommendation for
generalized use.
The data obtained from this work suggest that this model ecosystem is useful for the
determination of the uptake and persistence of pesticides by the organisms-. In general,
it was found that most chemicals, with the exception of the persistent soil insecticide,
dieldrin, underwent extensive degradation under the experimental conditions of the
system. Dieldrin was exceptional in its behavior in that >96% of the radioactivity
isolated from the organisms was unchanged dieldrin, clearly indicating the extreme
inertness of this chlorinated hydrocarbon to undergo biological or chemical
modification.
17a. Descriptors
*Ecosysterns, Trophic levels, *Pollutants, *Pesticide residues, *Biodegradation,
Ecological distribution
l"b. Identi inrs
Model ecosystem, Insecticides, Herbicides, Plasticizers, Polychlorinated Biphenyls,
Bux, Carbaryl, Carbofuran, Dieldrin, Lindane, Orthene, Parathion, Alachlor, Propachlor,
Bladex, Bentazon, Dicamba, Pyrazon, 2,4-Dichlorophenoxyacetic Acid, Trifluralin, Banomit
DOP, Chlorinated Biphenyls, Captan, Hexachlorophene, Fish, Snail, Algae
05A, 05B
19. S1 -\rity C' ss.
di'i.
21. A«j. of
Pc.Se-
2t. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D C 2O24O
James R. Sanborn
Illinois Natural History Survey
•if U.S. GOVERNMENT PRINTING OFFICE: 1975-697-819/77 REGION 10
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