PESTICIDE RESIDUES IN FOOD - 1982
Sponsored jointly by FAO and WHO
EVALUATIONS 1982
Data and recommendations of the joint meeting
of the FAO Panel of Experts on Pesticide Residues
in Food and the Environment and the
WHO Expert Group on Pesticide Residues
Rome, 23 November - 2 December 1982
Food and Agriculture Organization of the United Nations
Rome 1983
ETHIOFENCARB
Explanation
Ethiofencarb was first evaluated by the 1977 Joint Meeting on
Pesticide Residues (FAO/WHO 1978)1 and a temporary ADI was allocated
based on the no-effect level observed in a 4-week oral study on the
rat.
The 1977 JMPR requested the submission of the results of the
reproduction study in progress for the 1978 JMPR. Since the required
study was not available, the 1978 and 1980 JMPRs extended the
temporary ADI until 1982.
The required reproduction study, a Salmonella/microsome
mutagenicity test, and an embryotoxicity and teratogenicity study have
been submitted and are summarized in the following monograph addendum.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
TOXICOLOGICAL STUDIES
Special Studies on Reproduction
Groups of rats (10 male and 20 female, Long Evans FB 30 strain,
rats/group) were fed ethiofencarb (technical grade, purity not stated)
in the diet at dosage levels of 0, 330 and 3 000 ppm and subjected to
two-litter per generation, three-generation reproduction study. The
rats were treated with the test compound throughout the study,
including mating, gestation and lactation. The adult rats were weighed
weekly. The body weights of the pups were measured immediately after
delivery, five days after birth, one week after the birth, and
thereafter at weekly intervals. The rats selected for the study were
fed from 45 days of age until sexually mature (ca. 100 days), when
they were mated to initiate the study.
1 See Annex 2 for WHO and FAO documentation.
During the mating period, two female rats were housed together
with one male rat for 21 days. The male rats were rotated so that each
female was paired with three different males for a period longer than
one oestrous cycle. Immediately after the pups were delivered, their
number and weights were recorded. Litters containing more than 10 pups
were reduced on the fifth day after delivery to 10 pups each,
whereupon the weights of these litters were again measured. The pups
were nourished for up to 4 weeks, during which time they were weighed
weekly; then the offspring of each first mating (F1a, F2a, F3a
generation) were sacrificed, as were the pups of the F3b generation.
The parental animals were again mated to provide a second litter,
which became the parental animals for the second generation.
Again pups were weaned after 4 weeks and reared up to an age of
100 days. Ten males and 20 females from the second litters (F1b, F2b)
were selected for the succeeding generation.
Gross and histopathological examinations were performed on major
organs and tissues of one male and one female pup (4 weeks old) of the
F3b generation from each of 10 mothers in each group.
In parental generation (Fo, F1b, F2b), there were no clinical
symptoms and no mortality attributable to treatment (some animals in
the control and treated groups died of pneumonitis). Body weight
curves of females of the F0, F1b and F2b generation, at 3 000 ppm
and of males of the F2b at 3 000 ppm were lower than that of control
group. Pregnancy rate was lower than the control in F0 animals at
first mating (F0-F1a) in the 1 000 and 3 000 ppm group, comparable
to the control in the F1b - F2a- F1b- F2b and F2b-F3a at all
levels, and again lower than control in the F2b- F3b at 3 000 ppm.
With regard to litter size (average number of pups/litter) and
viability index (5-day survival rate), a lower viability index in the
F2b at 3 000 ppm, a lower litter size and viability index in the F3a
and F3b at 3 000 ppm with slight effects also at 1 000 ppm were
observed. Lactation rates were impaired in the F3a and F3b at
3 000 ppm. Average body weight of pups at birth were lower than the
control in the F1b at 1 000 ppm and 3 000 ppm, in F2a and F2b at
3 000 ppm, and in F2a and F3b at 3 000 ppm. Growth curves for the
pups during lactation were lower than the control in F1b at
1 000 ppm, in F2a at 3 000 ppm and in F2b at 1 000 and 3 000 ppm
(with a marginal less significant effect at 330 ppm).
Pups observed grossly immediately after birth and during the
lactation period did not reveal any signs of malformations.
At necropsy, gross and histopathological examinations did not
provide any indication of treatment-related alterations in the tissues
of the pups of the F3b generation at all levels.
On the basis of the data, the no-effect level may be considered
330 ppm with respect to the reproductive performance (Löser 1979).
Special Studies on Embryotoxicity and Teratogenicity
Groups of pregnant Wister KFM-Han rats (25 mated female
rats/group) were treated by intubation with ethiofencarb (94.6%
purity) in 2% carboxymethylcellulose Na+ salt aqueous solution at 0,
12.5, 25 and 50 mg/kg bw/day on day 6 through 15 of gestation. The
dams were sacrificed on day 21 and foetuses removed by caesarean
section. Foetuses were examined for external, skeletal and internal
malformations. No dam died in any group throughout the experiment. No
signs of toxicity or clinical symptoms were observed in the females of
all groups. There were no significant differences between the control
and treated groups with respect to mean food consumption. A slight
reduction in the mean corrected body weight gain of the 25 mg/kg/day
group (3%) compared to the control was observed. (Corrected body
weight gain = (final weight - uterus weight) - (weight gain on day 6;
in % weight on day 6).)
No foetolethality was observed in any group. There were no
significant differences between the control and treated groups with
respect to the numbers of pregnant females, implantations, abortions,
embryonal deaths (resorptions), number of live foetuses and their
distribution within the uterus horns, mean weight of live foetuses and
sex ratio of foetuses. No malformations or anomalies were seen at
the external inspections and in the skeletal investigations
(2/3 foetuses). There were no relevant differences in the skeletal
development between the control and treated groups. Internal
malformations were reported in the control group (2 foetuses with
dilated aquaeductus cerebri silvii and 2 foetuses with dilated kidney
pelvises), in the 25 mg/kg/day group (one foetus with dilated kidney
pelvises, one foetus with a medial dystopia of the right undescended
testes and one foetus with dilated aquaeductus cerebri silvii) and in
the 50 mg/kg/day group (one foetus with dilated kidney pelvis). These
findings are not believed to be related to treatment, as they occur
spontaneously in untreated rats of this strain. On the basis of the
data, ethiofencarb did not reveal embryotoxic and teratogenic activity
(Becker 1981).
Special Studies on Mutagenicity
Salmonella/microsome test
An evaluation of the mutagenic potential of ethiofencarb was
performed according to the standard Ames assay. Strains of
Salmonella typhimurium (TA 1535, TA 1537, TA 100, TA 98), with and
without a metabolic activation system (S-9 mix) derived from the liver
of Sprague-Dawley rats treated with a single intraperitoneal dose of
Arochlor 1254, were treated at concentrations of ethiofencarb (93.1%
purity) up to and including 2 500 µg/plate. Positive controls were
cyclophosphamide for TA 1535 and TA 100, and trypaflavin for TA 1537
and TA 98. Negative controls were the respective solvents (i.e.
dimethyl-sulphoxide for ethiofencarb and trypaflavin and demineralized
water for cyclophosphamide). Four plates/strain/dose/substance were
used. Two plates/group were used to determine the total number of
bacteria. Three further tests with TA 98 and TA 1535 and TA 100 were
repeated at concentrations of 3 000, 3 750 and 2 500 µg of
ethiofencarb/plate, respectively. A reproducible dose-dependent
increase in the number of mutants to a level double than that recorded
for the negative control, obtained with at least one strain, is
considered to be a positive result.
At concentrations up to and including 3 750 µg/plate ethiofencarb
did not reveal a bacteriotoxic effect.
With S-9 mix, a slight dose-dependent increase of number of
mutants (but less than double that of the negative control), was seen
on TA 100 in the main test and confirmed in the repetition test. A
similar finding on TA 98 was not confirmed in the repetition test.
Without S-9 mix, increases greater than double that of the
negative control were seen on TA 1535 and TA 100 in the main test and
confirmed in the repetition test. The positive controls increased the
number of mutants well above the double of those recorded for the
negative controls, and thus demonstrated the sensitivity of the system
and the activity of S-9 mix. The Salmonella/microsome test
revealed a weak although definite mutagenic activity of ethiofencarb
on S. typhimurium TA 1535 and TA 100 (Herbold 1979).
COMMENTS
Ethiofencarb was last evaluated for an acceptable daily intake
for man by the 1977 JMPR and a temporary ADI was allocated. The
submission of the results of reproduction studies in progress was
requested.
No-effect levels could be assessed with respect to newly
submitted reproduction and teratogenicity studies.
Although an Ames test showed slight mutagenic activity to
S. typhimurium (strains TA 1535 and TA 100), a dominant lethal study
in male mice indicated no mutagenic activity.
The evaluated data permitted the establishment of an ADI.
TOXICOLOGICAL EVALUATION
Level Causing no Toxicological Effect
Rat : 10 mg/kg bw/day
Dog : 1 000 ppm in the diet, equivalent to 25 mg/kg bw/day.
Estimate of Acceptable Daily Intake for Man
0 - 0.1 mg/kg bw.
FURTHER WORK OF INFORMATION
Desirable
Additional mutagenicity studies to clarify the mutagenic
potential.
REFERENCES
Becker, H. Embryotoxicity and teratogenicity study with HOX 1901 in
1981 rats. Final Report No. R2048 (Project No. 000033) from
Research and Consulting Company, Ltd., Itingen
(Switzerland), submitted to the World Health Organization by
Bayer, F.R.G. (Unpublished)
Herbold, B. HOX 1901. Salmonella/microsome test for detection of point
1979 mutagenic effects. Report No. 8559 (Study No. HOX 1901/003)
from Institut für Toxicologie, Bayer. Submitted to the World
Health Organization by Bayer, F.R.G. (Unpublished)
Loser, E. HOX 1901. Multi-generation reproduction study on rats.
1979 Report No. 8403 from Institut für Toxicologie, Bayer,
submitted to the World Health Organization by Bayer, F.R.G.
(Unpublished)
ETHIOFENCARB
Explanation
Ethiofencarb was evaluated by the 1977, 1978 and 1981 Joint
Meetings.1 Further residue data from supervised trials on crops on
which ethiofencarb is known to be used were considered desirable.
Additional information was provided on residues in crops treated
directly and in rotational crops as well as on the fate of residues.
RESIDUES IN FOOD AND THEIR EVALUATION
RESIDUES RESULTING FROM SUPERVISED TRIALS
Trials were carried out on several crops in the Federal Republic
of Germany (FRG), United Kingdom (U.K.) and the U.S. (Bayer AG
1978-79; Bayer UK Ltd. 1977-1980). The analytical methods used
measured ethiofencarb sulphone, an oxidation product of ethiofencarb
and its sulphoxide. The limit of determination was 0.01-0.05 mg/kg.
Vegetables
Croneton SL or 500 EC was used at rates of 0.3-0.5 kg a.i./ha in
the trials on broad beans, Brussels sprouts, kale, savoy cabbage and
lettuce. Potatoes were treated one to three times with Croten EC at
rates from 0.3 to 0.5 kg a.i./ha. Fresh potatoes were sampled on the
day of treatment and thereafter until 51 days post-treatment. Croneton
FE granules were applied at planting at dosage rates of 1.1-1.5 kg
a.i./ha, Residues in the tubers were below 0.05 mg/kg in all samples.
The results and details of the experiments are given in Table 1.
Cereal Grains
Oat and wheat seeds were treated with Croneton 40 DS at a rate of
180 g a.i./100 kg seed. Oat plants were sampled regularly beginning on
day 61 after treatment. The grains were analysed from 143 to 199 days
after treatment. Neither the plants nor the grains contained
detectable residues.
1 See Annex 2 for FAO and WHO documentation.
Table 1. Residues Resulting from Supervised Trials with Ethiofencarb
Application Residues (mg/kg) at intervals (days) after
application 1
Crop Country Year Rate Formulation Interval
No. (kg. a.i (days)
/ha) 0 1 4 7 11-14 21 34 51 143-178
Broad beans U.K. 1977 1 0.5 EC - 0.024
pods 0.024
Broad beans U.K. 1 0.5 EC - 0.037
pods U.K. 0.11
Brussels FRG 1978 2 0.3 SL 8 0.29 0.18 0.2 0.22
sprouts FRG 1978 2 0.3 SL 7 0.16 0.14 0.34 0.2
FRG 1978 2 0.45 SL 7 0.9 1.08 0.81 0.83
Kale FKG 1979 2 0.3 EC 14 3.3 5.1 1.1 0.76
Lettuce FKG 1978 2 0.3 SL 8 5.6 5.4 1.2 0.8
Lettuce FRG 1978 2 0.3 SL 7 5.2 4.4 2.4 2.2
Savoy cabbage FRG 1978 2 0.3 SL 8 1.1 1.2 0.43 0.47
Potato FRG 1979 3 0.5;0.4 EC 14 0.07 0.07 0.07 0.08
0.3
FRG 1979 3 9.5;0.4 EC 14 <0.05 <0.05 <0.05 <0.05 <0.05
0.3 13
Table 1. (con't)
Application Residues (mg/kg) at intervals (days) after
application 1
Crop Country Year Rate Formulation Interval
No. (kg. a.i (days)
/ha) 0 1 4 7 11-14 21 34 51 143-178
U.K. 1977 1 0.75
U.K. 1977 1 0.5 EC 0.034 <0.01
U.K. 1977 1 0.5 EC 0.032
U.K. 1977 3 0.5 EC 23,15 0.016
U.K. 1977 1 1.13 FE 0.024
U.K. 1977 1 1.5 FE 0.022
U.K. 1979 1 1.13 FE <0.05
U.K. 1979 1 1.5 FE <0.05
1 Sum of parent compound, its sulphoxide and sulphone.
Sugarbeet
Supervised trials on sugarbeet were carried out in the U.K.
during three years. The sugarbeet plants were treated With Croneton
EC at a dosage rate of 0.5 kg a.i./ha 2 or 3 times 18-26 or 81 days
apart. The roots and tops or foliage were sampled and analysed
separately. The residue on roots ranged from <0.01 to 0.026 or to
<0.05 mg/kg at intervals up to 112 days after treatment. The residues
in the tops were 2 mg/kg at 25 days, 0.36-0.39 mg/kg at intervals from
41 to 73 days and 0.055 mg/kg at 112 days after last application.
Rotational Crops
Peas planted as rotational crop in sandy soil received broadcast
treatment with ethiofencarb. The dosage ranged from 0.25 kg a.i./ha to
4.5 a.i./ha. Planting was from 29 to 362 days after application.
Samples were taken from 61 to 93 days after planting. Regardless of
the dosage and time elapsed, the residues were <0.01 or <0.02 mg/kg,
the limit of determination in all samples with a single exception. In
the latter case, 0.06 mg/kg residue was in the gree vine sampled 61
days after planting in a soil which had been treated 29 days earlier
(Mobay undated). Maize, grown in three fields was treated with
ethiofencarb at rates of 1.1, 2.2, 4.5 kg a.i./ha. Sowing was 29 days
after soil treatments. Green forage samples were taken at intervals
from 32-75 days after sowing. The kernel was sampled at day 75.
Residues in green forage ranged from 0.01 to 0.23 mg/kg, while one
kernel sample contained 0.01 mg/kg and the other two less than
0.01 mg/kg.
FATE OF RESIDUES
In Plants
In greenhouse trials, Arylmate 50% EC (25 mg a.i./plant) was
sprayed on potatoes at the 12-leaf stage by foliar application or the
diluted emulsion was added to the soil surface in the pot. After
sampling, the adhering soil was removed by washing from the plants and
the green portions (leaves and stems) and the roots or tuber were
analysed separately. Soil samples were taken respectively from the
upper 3 cm layer and from the 0-3, 3-6, 6-11 cm layers one day and 35
days after drench application (Takase and Yashimoto 1979). The
concentration of total residues was 54.6 mg/kg in the green portion 30
minutes after spraying. Ethiofencarb was rapidly converted to its
sulphoxide and sulphone in plants and soil. Rapid oxidation may also
occur during the analytical procedure; however 85% of ethiofencarb
could be recovered under the analytical conditions.
The level of total residue and the ratio of sulphoxide and
sulphone derivatives in potato plants are shown in Table 2. The
residue level in the roots or tuber were much lower. The concentration
maximum was observed 7 days after both applications when it was ca.
2.8 mg/kg and 1 mg/kg following foliar and drench applications
respectively. The residue level declined thereafter, and it was in the
range of 0.07-0.38 mg/kg 35 days after application. The major part of
the residue in the tuber was ethiofencarb sulphoxide while the parent
compound was present in small amounts in a few cases only.
Table 2. Ratios of Ethiofencarb and its Metabolites in Potato
Application Level (mg/kg) of Percentage ratio of compounds
Interval total residue
(days) foliar (F) Drench (D) S SO SO2
F D F D F D
1 34.9 7.8 11.8 40.4 80.1 55.9 8.1 4.1
2 38.7 8.6 81.2 10.2
4 28.3 41 0.7 7.0 84 82.9 15.3 10.1
7 25.7 51.9 0 1.8 75.3 78.9 24.7 19.3
14 13.7 19.6 0 0 55.5 80 44.5 20.3
21 8.7 9.3 0 47.1 64.2 52.9 35.8
35 4.2 5.3 0 27.8 52.1 72.2 47.9
1 Measured in green portions after foliar (F) and drench (D) application.
Experiments were carried out to identify non-extractable residues
in potato foliage (Dräger 1977). It was found that the non-extractable
radioactivity, amounting to approximately 10% of the total residue,
is attributable to the incorporation of the carbomyl 14C atom of
ethiofencarb in the glucose molecule derived from the starch
hydrolysis. Ethiofencarb was applied to Chinese cabbage at about the
12-leaf stage by foliar application (Takase and Yashimoto 1978). One
day after application, 89.7% of the applied ethiofencarb was
recovered. The total residue, 46.2 mg/kg, consisted on 28.4%
ethiofencarb, 69.7% sulphoxide and 1.9% sulphone derivatives. The
parent compound disappeared rapidly and it was not detectable from
the third day after treatment, when 93.4% of the total residue
(36.4 mg/kg) was the sulphoxide derivative. The total residue
gradually decreased while the ratio of sulphone to sulphoxide slowly
increased. The total residue, consisting of 60.3% sulphoxide and 39.3%
sulphone, was 18 mg/kg 38 days after treatment.
In Soil
The degradation of ethiofencarb in soil is slower than in plants.
The half life of residues was found to be approximately 120 days in a
soil of Ph 6 under natural field conditions. Residues were detectable
only to a depth of 40 cm in contrast to the higher mobility indicated
by laboratory experiments (Dräger 1977). The formation of sulphoxide
is also slower in soil than in plants. The parent compound was still
detectable 35 days after treatment; however, the major portion of the
total residue was the sulphoxide. Distribution rates of ethiofencarb
and its oxidative derivatives were found to be similar 35 days after
either foliar or drench application (Takase and Yashimoto 1979).
Under Field Conditions
The behaviour of ethiofencarb was studied under normal farming
practice on large scale. A 10 ha sugarbeet field, which was provided
with a drainage system, was treated twice with ethiofencarb at a rate
of 0.5 kg a.i./ha. Lactating dairy cattle were fed for 2 weeks with
2x20 kg treated sugarbeet leaves containing 0.4 mg/kg residue. Winter
wheat was sown after sugarbeet. Samples were taken from the treated
plants, soil, rotational crops, collecting points of the drainage
pipes, drinking water of a well situated 700 m from the field and from
milk of treated cows. The sugarbeet leaves contained residues in the
1 mg/kg range during the first few weeks, which declined to below
0.2 mg/kg at the time of harvest. The sugarbeet roots did not contain
measurable residues at harvest. Winter wheat was sown in a soil
containing 0.04 mg/kg residue in the 0 to 40 cm soil layer. Residues
amounting to 0.03 mg/kg were found only in the green plant samples
taken 179 days after sowing. No residue was detectable in wheat
samples taken later. The milk samples contained no measurable residue
at any time (<0.05 mg/kg).
The drainage water first appeared 7 months after the treatment of
the field and contained residues ranging from 0.002 to 0.009 mg/kg
during the next 6 months. The well water did not contain measurable
residue in the period up to 1.5 year after the application of
ethiofencarb. The residue in the soil declined to about 0.03 mg/kg
within a year after the treatment.
Light Stability
Ethiofencarb undergoes rapid degradation under UV or natural
sunlight either on silica gel plates or in a bi-distilled water
solution. The half life on silica gel irradiated with sunlight-
simulating fluorescent tubes was found to be 3 days. In water
containing 0.5% acetonitrile 50% of the parent compound degraded
under a mercury vapour lamp within 18-24 hours, while only 20%
degraded under a sunlight-simulating lamp after 5 days. The
degradation products identified in the water solution were the
sulphoxide derivative and the 2-formylphenyl-N-methyl carbamate
(Wilmes 1981).
NATIONAL MAXIMUM RESIDUE LIMITS
The maximum residue limits and preharvest intervals shown in
Table 3 were reported to the Meeting.
Table 3. National Maximum Residue Limits for Ethiofencarb
Preharvest
Country Crop Interval MRL
(days) (mg/kg)
Austria Fruit,vegetables 7 7.0
Bulgaria Cotton, fruit,peppers,
(field grown and
under glass), tobacco 4
Cyprus Beet, cereals, citrus
fruit, pome fruit,
potatoes, stone fruit,
tobacco, vegetables 3-4
Czechoslovakia Field beans 21
Vegetables 14
Denmark Beets, cereals, fruit,
vegetables 14
France Beets 7
Cereals 21
Fruit, vegetables 7 2.0
German Fruiting vegetables 4
Democratic Fodder crops, oilseeds,
Republic potatoes, sugarbeet,
feedstuffs 7
Bulb vegetables, fruit,
legume vegetables,
officinals, root vegetables,
drift-treated food crops 14
Table 3. (con't)
Preharvest
Country Crop Interval MRL
(days) (mg/kg)
Brassicas, cereals,leafy
and stem vegetables 21
Food crops for infant
diet 28
Federal Cherries, lettuce 4 10.0
Republic Apricot, artichoke,peach
of Germany Currants, plums 5.0
Pome fruits 4 3.0
Brassicas, excluding
cauliflower 4 3.0
Eggplant 2.0
Broad beans, green beans 4 2.0
Cauliflower, cucumber 1.0
Potatoes 14 0.5
Sugarbeet 0.1
Other plants 0.05
Israel Potatoes 4 1
Peppers (green) 5
Apples, brassicas,
cauliflower, celery,
Chinese cabbage,
cucumber, eggplant,
zucchini 7
Pecans 60
Potatoes 90 2
Italy Potatoes, tobacco 7
Vegetables 7 0.5
Fruit 14 0.5
Beets (incl. sugarbeet) 30 0.5
Peru Cotton, potatoes,
vegetables 7
Portugal Pole beans 4
Brassicas, lettuce 7
Apples, horse beans,
sugarbeet 21
Wheat 49
Table 3. (con't)
Preharvest
Country Crop Interval MRL
(days) (mg/kg)
Spain Cotton, fruit (incl.citrus),
maize, oilseeds,sugarcane,
tobacco, winter cereals 21
Potatoes, sugarbeet 21 or 28 3
Alfalfa 28
Sweden Apples, beets, cereals,
currants, field beans,
oilseeds, peas, plums,
raspberries, vegetables 21
Switzerland Cereals 28 0.02
Fodder beet 42
Fruit 21 0.2
Field beans 42
Peas 21
Sugarbeet 42
Vegetables (excl.spinach) 14 1.0
1 Spray application
2 Granule application in furrow
3 According to formulation
APPRAISAL
Ethiofencarb was evaluated by the 1977, 1978 and 1981 Joint
Meetings. Additional information has been provided on residues in
crops and on the fate of residues. Supervised trials were carried out
on various crops at the recommended dosage rates.
Residue levels on broad beans (green) were similar to those found
in the previous experiments and did not exceed 0.04 mg/kg 11 to 14
days after application. The residue in the pod ranged from 0.024 to
0.11 mg/kg. The residue concentrations in Brussels sprouts, kale and
lettuce were below 1.2 and 3 mg/kg respectively at intervals of 4 to 7
days after application.
Potato samples taken from 11 to 178 days after last treatment
contained residues below 0.05 mg/kg in each case. The residues in
cereal grains and green cereals grown after seed dressing were not
detectable. In sugarbeet roots, residues did not exceed 0.05 mg/kg.
The residues in sugarbeet tops ranged from 2 mg/kg at day 25 to
0.06 mg/kg at day 112.
The residue in soil is partly taken up by rotational crops. The
green part of pea and maize plants grown in a field treated with
ethiofencarb 29 days preplanting contained maximum residues of 0.06
and 0.23 mg/kg 61 and 75 days after sowing. The residues in peas and
maize kernels were below and at or below the limit of determination
(0.01 mg/kg) respectively. Ethiofencarb is rapidly converted to its
sulphoxide and, at a slower rate, to its sulphone in plants.
The total residue in the green part of the potato plants
gradually decreased after foliar application, but reached the maximum
7 days after drench application. The parent compound was non-
detectable at day 7, while the ratio of sulphoxide to sulphone
continually decreased.
Organic solvents extract the majority (approximately 90%) of the
total residue. The non-extractable radioactivity was found to be
incorporated into the glucose derived from the hydrolysis of starch.
The dissipation rate and the ratio of parent compound and its
oxidative metabolites were similar in Chinese cabbage and potato. The
degradation of ethiofencarb in soil is slower than in plants. The
major portion of total residue is the sulphoxide derivative. The
mobilities of the residues were found to be lower under field
conditions than in laboratory model experiments.
Ethiofencarb undergoes rapid degradation in water solution under
UV light while the degradation rate is slower under a sunlight-
simulating lamp. The ethiofencarb sulphoxide and 2-formylphenyl
derivative were identified in the water solution.
RECOMMENDATIONS
In the light of the new information received, the Meeting
reconsidered the results of supervised trials listed in the 1977 and
1981 evaluations. On the basis of the whole set of data the following
amendment is recommended:
Commodity MRL Preharvest interval on which
(mg/kg) the recommendation is based
(days)
Brassicas(except Chinese
cabbage) 2 1 4
Chinese cabbage 5 4
1 Revised from 5 mg/kg
REFERENCES
Bayer AG. Pflanzenschutzmittel-Rückstände (Pesticide Residues).
1978-79 Brussels sprouts-Report Nos. 2047/78, 2049/78, 2006/79;
Kale-Report No. 2004/79; Lettuce-Report Nos. 2050-2051/78;
Oats-Report No. 2010/80; Potatoes-Report Nos. 2000-2001/79;
Savoy cabbage-Report No. 2052/78; Wheat-Report Nos.2010/79,
2041/79.(Unpublished)
Bayer U.K. Ltd. Agrochemicals Division-Technical Reports TCR 142,
1977-80 16.8.77; TCR 159, 15.3.78; TCR 182, 10.3.80. (Unpublished)
Dräger, G. Untersuchung des Metabolismus von Croneton in Kartoffeln;
1977 Versuche zur Identifizierung der nichtextrahierbaren
Rückstände in Kartoffellaub.
Bayer AG, Pflanzenschutz-Anwendungstechnik, Report RA-747.
(Unpublished)
Mobay Chemical Corp. Rotational crop residue experiment, Corn-Report
undated Nos. 67 187 - 67 189; Peas-Report Nos. 67 190 - 67 198.
Takase, I. and Yoshimoto, Y. Metabolic fate of ethiofencarb
1978 (O-ethylthiomethylphenyl methyl-carbamate) in Chinese
cabbage. Nitokuno Report No. 1o85 (RA). (Unpublished)
1979 Metabolic fate of ethiofencarb in potatoes and soil by
foliar and drench applications, Nitokuno Report no. 1095
(RA). (Unpublished)
Wilmes, R. Orientierende Lichtstabilität. Bayer AG, Pflanzenschutz-
1981 Anwendungstechnik. (Unpublished)
See Also:
Toxicological Abbreviations
Ethiofencarb (ICSC)
Ethiofencarb (Pesticide residues in food: 1977 evaluations)
Ethiofencarb (Pesticide residues in food: 1978 evaluations)
Ethiofencarb (Pesticide residues in food: 1980 evaluations)
Ethiofencarb (Pesticide residues in food: 1981 evaluations)
Ethiofencarb (Pesticide residues in food: 1983 evaluations)