PESTICIDE RESIDUES IN FOOD - 1983
Sponsored jointly by FAO and WHO
EVALUATIONS 1983
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
Geneva, 5 - 14 December 1983
Food and Agriculture Organization of the United Nations
Rome 1985
PROPOXUR
RESIDUES
Explanation
The Codex Committee on Pesticide Residues requested the Meeting
to reconsider the definition of the residue. The original data
submitted to the 1973 Meeting1 were studied and the relevant
information is summarized in this re-evaluation.
RESIDUES RESULTING FROM SUPERVISED TRIALS
Propoxur disappears from the treated surface mainly by
volatilization and only small amounts penetrate into the leaves. The
surface residue is not, or is only slightly, affected by
photodecomposition. Consequently, the major proportion of surface
residue is the intact parent compound. The portion of the residue that
penetrated into the plants was rapidly converted to water soluble
metabolites, namely 2-hydroxyphenyl-N-methylcarbamate (metabolite A)
and 2-isopropoxyphenyl-N-hydroxymethylcarbamate (metabolite B). The
metabolites are conjugated with plant glucosides and are not
extractable with organic solvents. In bean plants, the organosoluble
residue consisted of the parent compound in the amounts of 58.7
percent and 50.1 percent after three days and one day, respectively.
The results of supervised trials on fruit and vegetables, listed
in FAO/WHO 1973, were obtained by applying a method that measured the
parent compound only.
The residues in field crops were determined with a specific
method and conjugated metabolites were released by enzyme hydrolysis
before clean up. The original reports submitted for evaluation in 1973
indicate the levels of the parent compound and metabolites A and B, as
well as the total residue. The summary of these results is given in
Table 1, as they are not included in FAO/WHO 1973.
RECOMMENDATION
The Meeting concluded that the metabolites can be excluded from
the definition of the residue. The maximum residue limits (MRLs) refer
to the parent compound alone. As a result of the new definition of the
residue and reconsideration of experimental results, the limits for
cereal grains - 0.5 mg/kg, fodders and straws - 5 mg/kg and legume
animal feed (green) - 5 mg/kg must be changed. MRLs for fruit and
vegetables remain the same.
1 See Annex 2 for FAO and WHO documentation,
The new limits are:
cereal grains 0.1 mg/kg
fodders and straws 1 mg/kg
legume animal feeds (green) 1 mg/kg
Table 1 Propuxor residues resulting from supervised trials
Crop Dosage Interval after Residues (mg/kg)1
(mg a.i./ha) treatment
(days) Parent A B Total
Pasture grass 0.28 0 <0.01-19.4 (8)
0 11.8 <0.05 <0.02 11.82
1 7.8 0.98 0.09 8.83
3 4.5 2.3 0.19 6.99
7 0.02 0.92 0.08 1.02
Rangeland grass 0.28 0 29.8 <0.05 <0.03 29.80
1 5.28 <0.05 0.09 5.37
3 1.46 <0.05 0.03 1.49
7 0.56 0.09 0.11 0.76
2 x 0.56 3 0.09 0.31 0.19 0.59
7 0.53 0.47 0.2 1.2
10 0.08 0.48 0.2 0.76
Pasture grass 1.12 0 73.1 <0.05 0.03 73.13
3 0.74 0.73 0.69 2.16
7 0.22 0.57 0.7 1.49
14 0.08 0.13 0.28 0.42
21 0.05 0.15 0.12 0.32
Cereal grain 0.56 30-95 <0.01- 0.05- <.01- <0.05-
forage 0.79(7) 0.63 (7-) 0.37 (7-) 1.73
oats 0.56 + 0.422 93-96 nd-0.02(5) 0.05(5) <0.01
14 <0.04 <0.05 0.09 0.09
14 0.09 0.06 <0.01 0.15
Alfalfa 1.12 3 10.75 1.22 0.19 12.26
1.43 0.53 0.21 2.17
1.7 0.2 0.16 2.06
0 36.81 <0.05 <0.03 36.8
3 2.83 0.45 0.12 3.4
7 0.65 0.38 0.12 1.15
Barley 13 <0.04 <0.05 <0.02 <0.05
straw 14 0.24 <0.05 <0.01 0.24
straw 0.32 <0.05 <0.01 0.32
Rye 14 <0.02 <0.01 <0.01
Wheat 14 <0.01 <0.05 <0.01 <0.05
straw 0.21 <0.05 <0.01 0.21
1 The figures in brackets indicate the number of trials.
2 0.56 mg a.i./400 kg seed + foliar treatment with 0.42 mg a.i./ha.
See Also:
Toxicological Abbreviations
Propoxur (ICSC)
Propoxur (WHO Pesticide Residues Series 3)
Propoxur (Pesticide residues in food: 1981 evaluations)
Propoxur (Pesticide residues in food: 1989 evaluations Part II Toxicology)