DICOFOL JMPR 1974
Explanation
Dicofol was evaluated by the Joint Meeting in 1968 with a minor
amendment in 1970 (FAO/WHO, 1969, 1971). Tolerances of 5 mg/kg were
established for broad classes of fruit and vegetables, tea (dry
manufactured) and hops. The Codex Committee on Pesticide Residues
(CCPR) Meeting 1974 (Alinorm 74/24, pares. 91, 92 and 93) requested
the Joint Meeting to reconsider the tolerances with a view to making
more specific recommendations for fruit and vegetables and in the
light of new data provided by member governments.
Because of the structural relationship of dicofol to DDT, some
delegations at the CCPR meeting in 1974 further requested a
restriction in the use of dicofol.
RESIDUES IN FOOD AND THEIR EVALUATION
Impurities in technical dicofol
An investigation into the content of DDE in some commercial
formulations of dicofol has been carried out by the Food Inspection
Service at Amsterdam in 1973 (Anonymous, 1974). From the amounts found
in the formulations, it was calculated that the technical dicofol
contained 1-2% of DDE as impurity.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Two countries, namely the Netherlands and United Kingdom, have
responded to the request for residue data to support adjustment of the
present 5 mg/kg tolerance on fruits and vegetables. Data were supplied
from supervised trials on apples, cucumbers, gherkins, strawberries
and tomatoes, as summarized in Table 1.
From these data it is noted, confirming the data supplied
originally on supervised trials from the USA that tolerances below 5
mg/kg would be justified for cucumbers, gherkins, strawberries and
tomatoes under use patterns which correspond to recorded official
recommendations. In the case of apples, however, the residue data
indicate some variability, even under similarly described experimental
conditions, and the new data seem to support the existing tolerance of
5 mg/kg, particularly when it is borne in mind that dosage rates,
pre-harvest intervals, etc. may vary in agricultural practices in
various countries.
TABLE 1 Dicofol residues resulting from supervised trials
Application1 Dicofol residues (mg/kg) after interval (days)
Dosage Formulation
Crop Country Year rate 0-1 3-4 7-8 14-16 22-29 35-48 105
Apples Netherlands 1957 1.5-3.7 25% w.p. 1.3- 0.2- 0.1-
g/tree 2.8 2.0 3.0
Netherlands 1967- 610-750 18.5% w.p. 0.07- 0- 0- 0.08- 0.12-
1970 g/ha 1.08 0.52 0.38 0.32 0.22
U.K. 600 g/ha 2.5± 1.02± 0.30±
0.2 0.16 0.12
Cucumbers Netherlands 1961 1.8 kg/ha 18% w.p. 0.13- 0.15-
0.24 0.30
Netherlands 1961 2.3 kg/ha smoke 0.03- 0.01-
0.09 0.03
U.K. 300-600 15% c.c2 0.16- 0.15- 1.51-
g/ha 0.88 0.73 1.82
Gherkins Netherlands3 1970 1.1 18.5% w.p. 0.5- 0.1-
kg/ha 1.1 0.8
Strawberry Netherlands3 1971 0.5 18.5% w.p. 0.05-
kg/ha 0.3
U.K. 0.9 20% w.p. 0.49 0.88
kg/ha
Tomatoes Netherlands3 1973 0.4 18.5% w.p. 0.23-
kg/ha 0.54
1 Single application unless otherwise stated.
2 Data include residues from both low and high volume spraying. Low volume residues are higher.
3 By gas chromatography. All other results by colorimetric procedures.
NATIONAL TOLERANCES REPORTED TO THE MEETING
Country Commodities Tolerance
(mg/kg)
Australia Almonds, fruit (except citrus),
vegetables 5
Canada Almonds, apples, apricots, beans,
blackberries, boysenberries, cantaloupes,
cherries, chestnuts, crab apples,
cucumbers, dewberries, eggplant, figs,
filberts, grapes, hickory nuts, honeydew
melons, loganberries, muskmelons,
nectarines, peaches, pears, peas, pecans,
peppers, pimentos, plums, pumpkins,
quinces, raspberries, soybeans,
strawberries, summer squash, tomatoes,
walnuts, watermelons, winter squash 3
Netherlands Apples, pears, gherkins, cucumbers 1
Melons, strawberries, tomatoes 0.5
USA Dried tea 45
Hops 30
Mint hay 25
Apricots, grapefruit, kumquats,
lemons, limes, nectarines,
oranges, peaches, tangerines 10
Apples, beans (dry form); beans,
snap (succulent form); beans, lima
(succulent form); blackberries,
boysenberries, bushnuts, butternuts,
cantaloupes, cherries, chestnuts,
crab apples, cucumbers, dewberries,
eggplants, figs, filberts, grapes,
hazelnuts, hickory nuts,
loganberries, melons, muskmelons,
pears, pecans, peppers, pimentos,
plums (fresh prunes), pumpkins,
quinces, raspberries, summer squash,
strawberries, tomatoes, walnuts,
watermelons, winter squash 5
Cottonseed 0.1
APPRAISAL
Dicofol is an organochlorine compound, structurally related to
DDT but with practically no insecticidal activity. Although its use
has always been minor in comparison with other organochlorine
compounds, it remains important in many countries especially against
organophosphorus-resistant mites.
Previously established tolerances of 5 mg/kg for dicofol on fruit
and vegetables have been referred back by the CCPR to the Joint
Meeting, requesting re-examination to determine whether tolerances on
specific crops could be recommended.
Information has been given to the Joint Meeting that impurities
of DDE up to 1-2% may be present in technical dicofol. No data on DDE
residues deriving from this source were available, but it could be
calculated that such residues would be detectable in food for human
consumption only in a limited number of cases, and even then in
amounts which would be quite insignificant, when good agricultural
practice was followed. Similarly the Meeting considered that possible
contributions to present DDE levels in food chains from this source
would be insignificant. On the basis of the information available
therefore, the Meeting could make no further recommendations
concerning the discontinuation of the use of dicofol.
New residue data on apples, cucumbers, gherkins, strawberries and
tomatoes were received from two countries. They were examined in
conjunction with the data on the same crops previously filed with FAO
and it was considered that the limit for residues on apples could not
be set below 5 mg/kg. However, the data justified a lowering of the
limit on cucumbers and gherkins to 2 mg/kg and on strawberries and
tomatoes to 1 mg/kg.
No further consideration can be given to other tolerances on
individual crops until additional information becomes available on use
patterns and residues in various countries.
RECOMMENDATIONS
TOLERANCES mg/kg Pre-harvest
interval on which
recommendation
is based
Fruits (other than exceptions noted) 5
Vegetables (other than exceptions noted) 5
Cucumbers* 2 2 days
Gherkins* 2 2 days
Strawberries 1 7 days
Tomatoes* 1 3 days
* New Tolerances
FURTHER WORK OR INFORMATION
DESIRABLE
Results of residue studies to indicate the level of residues in
various fruits and vegetables following currently approved use
patterns.
REFERENCES
FAO/WHO. (1969) 1968 Evaluations of some pesticide residues in
food. FAO/PL/1968/M/9/1; WHO/Food Add./69.35.
FAO/WHO. (1971) 1970 Evaluations of some pesticide residues in food.
FAO/AGP/1970/M/12/1; WHO/Food Add./71.42.
Anonymous. (1974) Specific information to Joint Meeting from the
Netherlands. (Unpublished).