CAPTAFOL JMPR 1976
Explanation
This fungicide was evaluated by the Joint Meetings in 1969,
1973 and 1974 (FAO/WHO 1970b, 1974b and 1975b).
The 1973 Joint Meeting considered the following information
desirable.
1. Studies to investigate the metabolism of the
tetrachloroethylthio-moiety of captafol.
2. Data on effects of washing, peeling, and blanching on residue
levels in various crops.
3. Data on residue levels in commodities moving in commerce.
4. Additional data and information on agricultural practices in
user countries with respect to asparagus, beans, cabbage, celery,
citrus fruit, coffee, grapes, lettuce, pineapple, strawberries
and tea.
No new data were obtained on question 1 and only limited data
on questions 2 and 3. Information was received on both uses and
residues resulting therefrom on pineapple but not on any other
crops mentioned in question 4. However some information was
provided on extensions of the use pattern in some countries on pea
nuts, potatoes, tomatoes and wheat, and on the resulting residues.
A further evaluation of captafol for acceptable daily intake
is planned for 1978, for the reasons given in the Report of the
present Meeting (FAO/WHO, 1977a).
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Information on recently introduced uses of captafol is given
in Table 1.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Residue data became available from supervised trials on
pineapple and on some crops not included in the 1973 monograph,
namely peanuts, potatoes, tomatoes and wheat. A summary of the data
is provided in Tables 2-4.
TABLE 1. Use pattern. Information not included in the monographs of the 1969, 1973
and 1974 Joint Meetings
Application Recommended
pre-harvest
Target No. of Mode of interval In use
Crop Country organism treatments kg a.i./ha treatment (days) since
peanuts U.S.A. 5-10 1.5 spraying 14 1973
pineapple South heart rot 4 times 8 spraying (200 21 1973/
Africa monthly g a.i./100 l) 1974
potatoes South early & 7-11 max. 1.6 spraying at 7 3 1972
Africa late day intervals
blight
U.S.A. early & 1971
late
blight
tomatoes South early & 4-5 max. 4.8 spraying at 7 3 1972
Africa late day intervals
blight (160 g a.i./
100 1).
wheat Netherlands mildew and 1 1 one or two sprayings 42 1975
ripening mixed with from development
diseases other of the ear until the
fungicides until the beginning
of flowering Feekes
scale 10.1 - 10.5.1.
Peanuts (Chevron 1975)
Thirteen experiments were carried out in 1973 and 1974: 4 in
Florida, 3 in Texas, 2 in Georgia, 2 in Alabama, 1 in Oklahoma and 1
in North Carolina.
In all the experiments the fungicide was applied at the
recommended rate i.e. 1.5 kg a.i./ha. Multiple applications were made
6-10 times, using ground or air equipment.
The peanuts were dug 9-27 days and combined 16-28 days after the
last application.
Residues were determined on whole pods, hulls, shelled nuts, oil,
meal, peanut butter, roasted beans and vines at various stages of
dryness.
The maximum residues observed after application of 1.5 kg a.i./ha
were:
maximum residue
commodity in mg/kg
whole mature pods 0.46
hulls 1.3
shelled nuts <0.01
oil (hexane extracted or hydrolic
pressed) <0.01
peanut meal <0.01
peanut butter <0.01
Details are given in Table 2. In the Table the residues of
captafol in shelled nuts, peanut meal, peanut oil and peanut butter
are omitted since the maximum residue values found were all at or
about the limit of determination.
FATE OF RESIDUES
In animals
A feeding study was carried out in which 6 mature lactating
Holstein cows, all at a medium stage of lactation, received either 5.7
or 11.4 mg 14C-captafol orally for 30 days. These levels correspond
to 0.5 and 1 ppm respectively in the total diet. The latter levels are
considerably higher than those which would occur from the inclusion of
peanut hulls or potatoes at normal proportions in the total diet.
TABLE 2. Residues of captafol in peanuts in U.S.A. (Chevron, 1975)
Interval after application
14-17 days
Application Residue, mg/kg Residue, mg/kg
moisture moisture
Year rate formulation whole content whole content
no kg a.i./ha pods hulls vines vines % pods hulls vines vines %
1973 10 1.5 wp 0.04-0.07a 0.57-0.64a 20-23a 75a 13-14a 14a
1973 10 3 wp <0.01-0.27 76-90 75
1973 10 1.5 wp 0.06-0.14 1.1 - 1.3 184-230 21.5
1973 9 1.5 wp 0.25-0.46 1.1 - 1.3 194-211 21.8
1973 9 3.0 wp 1.1 - 1.4 568-588 20.4
1973 7 1.5 wp <0.01-0.02 0.45-0.50 117-176 9.9
1973 7 3 wp <0.01-0.02 100-203 13.7
1973 11 1.5 wp <0.01 <0.01 24-30 16.6
1973 8 1.5 wp 0.02-0.11 0.48-0.97 82-97
1973 8 3.0 wp 0.04-0.08 32-33
1974 8 1.5 wp 0.09-0.15 1.3 - 1.4 75-102 14.5
1974 10 1.5 110-122b 78b 0.36-0.39b 39-52b 38b
1973 5 1.2 0.02-0.02 0.03-0.08
1973 5 2.4 0.02-0.03 0.13-0.16
1973 11 1.2 <0.01-0.01 0.49-0.88 101-109
1973 11 2.4 0.01-0.01 1.25-1.27 85.5-107
1974 7 1.5 0.18-0.23
1974 10 1.5 0.36-0.39
42-50 days 51-54 days
4 1.2 wp <0.01-0.02 0.06-0.11
4 2.4 wp <0.01 0.25-0.51
5 1.0 wp 0.03-0.04 0.17-0.24 36-82.9
5 2.0 wp 0.01-0.03 0.26-0.45 122-133
1973 10 1.5 wp 7.6-11.0a 12.2a
1974 10 1.15 wp 39-41b 13.5b
a Results from a single trial
b Results from a single trial
TABLE 3. Residues of captafol in pineapple, potatoes and tomatoes
Residues, mg/kg, at interval (days)
Application after application
rate formulation
Crop Country no kg a.i./ha 0 1-3 7 13/14 27/28 89
Pineapple South 41 200g/100 l wp
Africa
whole fruit 15.7 22.8 1.6 5.1 2.5
rind 35.5 55.6 23.8 8.6 6.25
pulp <0.3 <0.3 <0.3 <0.3 <0.3
Potatoes South 11 1.6 kg/ha wp <0.05
Africa
Tomatoes South 4 2.4 wp 4.7 4.1, 2.4 2.5
Africa 2.9
1 monthly
TABLE 4. Residues of captofol in wheat
Residues, mg/kg, at interval (days) after
Application application, average (range)
Wheat no rate formulation
fraction Country Year kg a.i./ha 38 42/43 48 66 Ref.
grain Netherlands 1974 1 0.75 wpa (<0.05-<0.05) ICI
1974 1 1.00 wpa (<0.05-<0.05) 1975
grain 1975 1 1.0 wpa 0.03 ICI
(0.01-0.09) 1975
straw 3.6
(1.5-4.8)
grain 1975 1 1.0 wpa 0.1 ICI
(0.07-0.14) 1975
straw 1.8
(0.7-2.9)
grain 1975 1 1.0 wpa <0.01 ICI
straw <0.01 1975
grain 1975 1 1.0 wpa <0.01 ICI
straw 1.3 1975
grain 1975 1 1.0 wpb <0.01 ICT
straw <0.1 1975
grain 1975 1 1.0 wpb 0.05 CIBA-
straw 1.0 wpb 0.22 Geigy
(0.16-0.31) 1975
grain 1975 1 1.0 wpb 0.05 Ciba-
Geigy
straw 0.74 1975
(0.51-0.87
a mixture with ethirimol b mixture with CGA 30599
For peanut hulls, the maximum used in the diet is 20%, in most
instances only 10% in a maize/soybean base diet. For peanut meal the
maximum amount in the diet could be about 25%, with the normally used
maximum being 10%.
The maximum residue level found in peanut hulls, after 6-11 spray
applications at the recommended rate of 1.5 kg a.i./ha was 1.3 mg/kg,
thus leading to a maximum of 0.26 mg/kg in the diet. The peanut meal,
with maximum levels of 0.03 mg/kg will not contribute significant
captafol residues. The feeding levels chosen are 5-10 times higher
than the amounts in the total diet derived from potatoes, when these
constitute no more than 20% of the total diet and residues are
approximating the proposed maximum residue limit of 0.5 mg/kg. 20%
potatoes is the maximum ratio recommended, normally the proportion is
lower.
An excellent recovery of captafol was obtained in this study, the
range being 84-101%. By far the major route of excretion was the
urine, with faeces accounting for a lesser but significant quantity.
In the same feeding study Bio-Test Laboratories (1970) showed that
captafol was rapidly excreted from cows receiving daily oral doses of
14C captafol. The major excretion route was the urine, the remainder
(about 10%) being excreted in the faeces. No captafol was found in
either the milk or tissues at any time. The total concentration of
captafol and its main metabolites containing 14C in whole milk at
any time was also insignificant (< 0.01 mg/kg).
Radioactivity was monitored in samples of milk, tissue, urine and
faeces. The average counting efficiency was 70% in the milk samples,
58% in blood and 54% in tissue. The limit of detection of
radioactivity in this study was set at 20% above background. From the
data the following limits of detection of captafol and its 14C-
metabolites may be calculated.
milk 0.0004 mg/kg Captafol + 14C-containing
metabolites calculated
as captafol
fat 0.004 mg/kg " "
blood 0.002 mg/kg " "
other tissues 0.002 mg/kg " "
(Chevron 1970)
Milk
At the lower feeding rate of 5.7 mg 14C-captafol the levels of
14C calculated as captafol equivalents found in the daily pooled milk
varied between 0.001 and 0.003 mg/kg. Two days after the last dosing
no residues could be detected in the milk. At the feeding rate of
11.4 mg captafol the corresponding levels ranged from 0.002 to
0.006 mg/kg. The levels of 14C in the milk of treated cows followed a
rapid equilibration and elimination pattern. Within 24 hours of the
first dose the radioactivity in the milk reached a level which was not
exceeded during the entire 30 days dosing period. Once the
administration of captafol was stopped the 14C concentration in the
milk dropped quickly; two days later no measurable amounts of 14C
were found. (Chevron, 1970)
Tissues
14C captafol residues (mg/kg total metabolites calculated as
captafol) were measured in tissues obtained from cows, 24 hours and 8
days after the last dose of 14C captafol. In the former group the
levels of radioactivity did not exceed 0.01 mg/kg of total metabolites
except in liver and kidney. Since it was shown that over 90% of the
administered dose was excreted in the urine it is not surprising that
the concentration of 14C was somewhat higher in these organs (Table
5).
Blood
Only traces of radioactivity were found in the blood, the highest
value being 0.005 mg/kg.
In storage, processing and cooking
Only limited data were obtained on the effect of household
washing on captafol residues. In an experiment on leeks (ten Broeke
and Dornseiffen 1973) it was shown that normal household washing
removed 62-84% of the residue (Table 6).
NATIONAL TOLERANCES REPORTED TO THE MEETING
Since the 1969 and 1973 evaluations of captafol (WHO/FAO 1970b,
1974b) the national tolerances for several commodities have been
amended and new tolerances for other commodities established.
APPRAISAL
This fungicide was evaluated by the Joint Meetings in 1969, 1973,
and 1974 (FAO/WHO, 1970b, 1974b, 1975b).
Only limited information was obtained on the questions listed as
desirable in the 1973 evaluation. Of the crops on which captafol is
authorised or recommended in various countries and on which further
information was desired, additional data became available only on
residues and use on pineapple. No information was obtained about uses
on asparagus, beans, cabbage, celery, citrus fruit, coffee, grapes,
lettuce, strawberries or tea and the maximum residue limits concurrent
with these uses.
TABLE 5. 14C residues in cow tissues
Total metabolites calculated as captafol, mg/kg
Feeding level 5.7 mg 14C captafol/day 11.4 mg 14C captafol/day
Time Tissues Cow no. 1 2 3 4 5 6
brain 0.001 0.003 0.006 0.003
heart 0.002 0.001 0.005 0.006
day muscle 0.002 0.004 0.006 0.008
30 fat 0.001 0.000 0.001 0.001
liver 0.005 0.005 0.010 0.019
kidney 0.007 0.006 0.014 0.021
brain 0.001 0.003
heart 0.001 0.002
day muscle 0.002 0.004
38 fat 0.000 0.001
liver 0.002 0.004
kidney 0.002 0.003
TABLE 6. Effect of washing on captafol residues in leeks (ten Broeke and Dornseiffen, 1973)
Application Residues, mg/kg, at interval(days) after application, mean (range)
Country rate formulation 7 14/14 20/21
Crop & year no kg a.i./ha unwashed washed unwashed washed unwashed washed
Leek Netherlands 6 1.2 EC 384 g/l
1972
var.Olifant 4.7 1.8 3.2 0.4 1.7 0.3
(3.0-6.2) (1.0-2.4) (1.6-5.1) (n.d.-0.9) (1.1-3.4) (0.3-0.4)
var.Iglo 2.6 0.5 1.4 0.2 1.5 0.2
(2.0-3.4) (0.2-0.9) (0.6-2.5) (0.2-0.3) (0.7-4.0) (0.1-0.6)
TABLE 7. National tolerances reported to the Meeting
Maximum residue limit
Country Commodity mg/kg
Australia apricots, nectarines, peaches 15
cherries (sour) 5
other fruit & vegetables 2
cucumbers, melons 2
cherries (sweet) 2
Belgium fruit & vegetables, except 3
potatoes
Canada peaches 15
cherries (sour) 10
tomatoes 5
cherries (sweet), cucumbers, 2
melons
Fed.Rep. of leaves of celeriac, leek,
Germany lettuce 7-5
fruit of vegetables (incl.
tomatoes, cucumbers, gherkins,
eggplant) 5
fruit 5
other commodities of plant
origin 0.2
Japan cabbage, radish (leaves &
roots), sweet potatoes, tea 1
apples, japanese pear 5
Netherlands (1 tolerance under consideration; it may be expected
that the revised tolerances will come into force in
1977)
peaches 151
cherries (sour 101
other fruits 51
leek 8
fruits of vegetables, i.e. bell
peppers, eggplant, cucumbers,
melons, tomatoes 51
other vegetables 3
raw grain 0.2
other food commodities 0.05*
South Africa pineapple 10
potatoes, tomatoes 5
TABLE 7. (Cont'd.)
Maximum residue limit
Country Commodity mg/kg
U.S.A. cherries (sour) 50
apricots, peaches 30
tomatoes 15
cranberries 8
melons 5
cherries (sweet), cucumbers,
nectarines, peanut hulls, plums 2
citrus fruits, potatoes 0.5
apples 0.25
corn (incl.sweet corn) kernels &
cob, husk removed, macadamia
nuts, onions, pineapple 0.1**
peanuts (meals with hulls removed 0.05**
taro corn 0.02**
* at or about the limit of determination.
** negligible residues.
The information obtained on residues on pineapple includes a use
which was not evaluated at former Meetings. For this crop an amendment
of the earlier established maximum residue limit is recommended. Since
no additional information was obtained on other use patterns covered
in earlier monographs, except some data on residues on tomatoes, the
limits previously recommended are retained.
Some information was provided on extensions of the use pattern in
some countries and on residues occurring in crops at harvest as a
consequence of these applications. These new data allow additional
maximum residue limits to be recommended for peanuts and wheat.
Limited information was obtained on the effect of washing,
cooking and processing. In a supervised trial on leeks it was shown
that 62-84% of the residue remaining on the crop as marketed was
removed by normal household washing.
RECOMMENDATIONS
The following temporary maximum residue limits are recommended in
addition to or amending those previously recommended.
Pre-harvest intervals
Limits on which recommendations
Commodity mg/kg are based(days)
Pineapple(whole fruit) 10 21
Peanut hulls 2 14
Peanuts 0.5 14
Wheat 0.2 42
Peanut kernels 0.05 14
FURTHER WORK OR INFORMATION
REQUIRED (by 1978)
1. Further studies to assist evaluation of histopathological
changes in the kidneys and liver of rats.
2. Studies to investigate the lymphocyte-neutrophil shift
noted in previous experiments.
DESIRABLE
1. Further studies to investigate the metabolism of the
tetrachloroethylthio moiety of captafol.
2. Considerably more information from countries where captafol is
used to clearly indicate use patterns and resulting residues.
3. Further data on the effects of washing, peeling and
blanching on residue levels in various crops.
4. Information, including information from studies now
in progress, on new methods for the analysis of the parent
compound together with the main metabolites in products of animal
origin.
5. Results of on-going studies to show the level and nature of
captafol residue in meat, milk, poultry and eggs.
6. Results of studies now in progress to show the fate of captafol
residues in citrus and citrus pulp.
REFERENCES
Bio-Test Lab. Milk and meat residue studies in dairy cows.
1970 Report provided to Chevron no. IBT 78909.
ten Broeke, R. & Dothseiffen, J.W. Residues of captafol
1973 on leek. Unpublished report no. 169 Food
Inspection Service, Amsterdam (in Netherlands
language).
Chevron The fate of difoletan in lactating cows.
1970 Unpublished Report Chevron Chemical Company no.
72114.
Chevron Difoletan residues in peanuts. Unpublished Report
1975 provided to Joint Meeting 1976.
Ciba-Geigy Residues in winter wheat (grain and straw) after
1975 treatment with RTilt 60 w.p.
ICI Residues in cereals, trials in Holland 1974.
1974 Unpublished report provided by the Netherlands to
1974 Joint Meeting 1976.
ICI Residue summary ethirimol/captafol in cereals.
1975 Unpublished report no. BPA/YV/132/09.01.76
provided by the Netherlands to Joint Meeting 1976
Olthof, P.D.A., & Lagemaat, L. Residues of difoletan in leek.
1971 Unpublished Report no. 3886. Central Institute for
Nutrition and Food Research, the Netherlands.
de Vos, R.N., & Pot, W. Residues of difoletan in pears. Unpublished
1971 Report no. 3340. Central Institute for Nutrition
and Food Research, the Netherlands.
See Also:
Toxicological Abbreviations
Captafol (HSG 49, 1990)
Captafol (ICSC)
Captafol (PIM 097)
Captafol (FAO/PL:1969/M/17/1)
Captafol (WHO Pesticide Residues Series 3)
Captafol (WHO Pesticide Residues Series 4)
Captafol (Pesticide residues in food: 1977 evaluations)
Captafol (IARC Summary & Evaluation, Volume 53, 1991)