PESTICIDE RESIDUES IN FOOD - 1979
Sponsored jointly by FAO and WHO
EVALUATIONS 1979
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, 3-12 December 1979
PIRIMIPHOS-METHYL
Explanation
Pirimiphos-methyl was evaluated in 1974, 1976 and 1977 and an ADI was
estimated and MRLs in a range of commodities were recommended. The
11th Session of the Codex Committee on Pesticide Residues requested
that the meeting should consider pirimiphos-methyl residues in kiwi
fruit.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Kiwi fruit (Actinidia chinensis) is now the second largest
horticultural product exported from New Zealand, the value being in
excess of U.S. $20 million annually. The fruit is subject to attack
by a number of pests and diseases and to meet plant health
requirements of countries importing New Zealand produced kiwi fruit,
it is necessary to spray regularly. Because of the hairy nature of
the skin, spray residues are retained on the fruit more than if the
skin was smooth. Trials data have shown that 90% of the pesticide
residues remain on the skin. The skin, being hairy, is relatively
unpalatable and normally discarded.
Pirimiphos-methyl has been under development for control of greedy
scale, Hemiberlasia rapax on kiwi fruit. The rate of application
ranges from 750-1250 g/ha with the minimum pre-harvest withholding
interval being 14 days.
Two sets of residue data were available both reflecting the use of EC
formulations. In the first set of work (O'Kane 1977),
pirimiphos-methyl was sprayed at 750 g/ha, with the results shown in
Table 1. In the second set of data (Cheong 1979), pirimiphos-methyl
was sprayed "high volume" using approximately 2500 l/ha of a 0.0475%
ai solution with the results as shown in Table 2. The analyses were
conducted by gas chromatography as reviewed at the 1974 and 1976
Meetings.
The results quoted relate to pirimiphos-methyl itself. No residues of
the phosphorus-oxygen analogue were recorded, which is consistent with
the results of the earlier work on other crops reviewed in 1976.
Table 1. Pirimiphos-Methyl Residues in Kiwi fruit sprayed 6 times at
14-21 days intervals at 750 g ai/ha
(New Zealand, 1976 - 1977)
Interval Between Residues of pirimiphos-methyl (mg/kg)
Last Application
and Harvest Edible pulp skin whole fruit
0 0.27 28,32 3.9
7 0.12 38 2.5
14 0.10 12,12 2.0
21 0.10 8.5 1.2
28 0.05 4 0.7
(O'Kane, 1977)
Table 2. Pirimiphos-Methyl Residues in Kiwi Fruit*
New Zealand, 1979
Interval Between Mean
Last Application Lowest Residue Highest Residue Residue
and Harvest Crop - Part Determined Determined Determined
(days) Analysed (mg/kg) (mg/kg) (mg/kg)
7 Whole Fruit 0.57 3.1 1.8 (3)
14 " 0.60 2.3 1.6 (3)
28 " 0.26 1.0 0.65 (2)
42-43 " <0.05 1.1 0.45 (3)
>56 " <0.05 0.15 0.09 (7)
14 Skin 5.3 10 8.1 (3)
28 " 1.6 3.9 2.8 (2)
14-28 Edible pulp <0.05 <0.06 <0.06 (5)
(Cheong, 1979)
Figures in parentheses are the number of results upon which the means are based.
* Sprayed at approximately 2500 litres per ha. with 0.0475% a.i.
APPRAISAL
Pirimiphos-methyl has been under development for the control of
greedy scale on kiwi fruit in New Zealand. Two sets of residue
data reflecting different methods of application during two
separate seasons have provided the basis for recommending maximum
residue limits. These data reveal that over 90% of the residue
is retained in inedible skin, there being no significant residue
in the edible pulp. The studies have confirmed that the residues
consist of the parent compound alone.
RECOMMENDATION
The following maximum residue limit is recommended. They refer
to pirimiphos-methyl alone.
Commodity Limit mg/kg Pre-harvest interval on which
recommendations are based
Kiwi fruit 2 14-21
REFERENCES
Cheong, H. Analysis of pirimiphos-methyl in kiwi fruit ICI (NZ)
Ltd. (1979) Unpublished residue data.
O'Kane. ACTELLIC: Kiwi fruit ICI (NZ) Ltd. (1977) Unpublished
residue data.
See Also:
Toxicological Abbreviations
Pirimiphos-methyl (WHO Pesticide Residues Series 4)
Pirimiphos-methyl (Pesticide residues in food: 1976 evaluations)
Pirimiphos-methyl (Pesticide residues in food: 1977 evaluations)
Pirimiphos-methyl (Pesticide residues in food: 1983 evaluations)
Pirimiphos-methyl (Pesticide residues in food: 1992 evaluations Part II Toxicology)