PARAQUAT JMPR 1978
Explanation
At the 10th Session of the Codex Committee on Pesticide
Residues, (Alinorm 79/24, para. 116), some delegations questioned
the need to set the maximum residue limit for paraquat cation on
sunflower seed as high as 2 mg/kg. As additional data were
available the Committee requested the Joint Meeting to reconsider
the limit at the earliest opportunity.
Extensive data were obtained from supervised trials carried
out in the USA in which paraquat was used as a desiccant and
against late developing broad leaf and grass weeds.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Paraquat is sprayed during the three weeks prior to harvest at
a dosage rate of 0.25-0.5 kg a.i./ha applied from the air or with
ground equipment. This use hastens the drying rate of mature seed,
reduces harvest losses and facilitates mechanical harvesting.
RESIDUES RESULTING FROM SUPERVISED TRIALS
The available data on residues in sunflower seed and its
products are summarized in Table 1. Residues up to 0.9 mg/kg were
found in the whole seed; no residues were found in the oil (limit
of determination 0.01 - 0.05 mg/kg), as would be expected owing to
the cationic nature of the compound. Residues up to 1.2 mg/kg were
found in sunflower meal. Samples of oil were taken on all sampling
dates; no residues were found.
The residues in seeds, hulls, meal and oil were determined
colorimetrically by a method based on that of Calderbank and Yuen,
cited in FAO/WHO 1971b.
APPRAISAL
Paraquat is used as a desiccant and herbicide shortly before
harvest (pre-harvest interval about 1 - 3 weeks). This use
accelerates the drying of mature seeds, reduces the harvest losses
and facilitates mechanical harvesting. Extensive residue data
became available from supervised trials, carried out in three
states of the USA. Residues up to 0.8 mg/kg were present in the
whole mature seeds at harvest. It may be expected that further
drying will increase the residue on a dry product basis to more
than 1 mg/kg. Residues up to 1.2 mg/kg were found in sunflower
meal, which is used as a component of compounded animal feed,
whereas the residues in sunflower oil were very low, at or about
the limit of determination of 0.01 mg/kg.
TABLE 1. Residues of paraquat in sunflower seed and its products (supervised trials, USA)
Residues (mg/kg) at intervals (days) after application
Commodity Country Year Application
rate, kg *
a.i./ha 0 7 14 21 Ref.
Sunflower USA 1972 0.5 0.04-0.04 0.52-0.32 0.42-0.81 1
seeds Minn.
seeds USA 1972 0.25 0.05-0.11 0.90-0.13 0.12-0.11
meal Minn. 0.14-0.10 0.23-0.17 0.11-0.15 1
hulls 0.08-0.07 0.10-0.07 0.07-0.09
seeds USA 1972 0.5 0.27-0.21 0.37-0.39 0.32-0.60 2
Minn.
seeds USA 1972 0.25 0.06-0.06 0.04-0.03 0.02-0.04
meal Minn. 0.10-0.02 0.05-0.07 0.05-0.04 2
hulls 0.06-0.06 0.04-0.06 0.02-0.02
seeds USA 1972 0.50 0.51-0.35 0.44-0.40 0.23-0.26 3
Calif.
seeds USA 1972 0.25 0.14-0.12 0.11-0.09 0.10-0.11
meal Calif. 0.20-0.17 0.17-0.20 0.18-0.18 3
0.14-0.16 0.14-0.11 0.08-0.11
seeds USA 1977 0.50 0.16-0.16 0.35-0.35 0.23-0.23
meal Calif. 0.35-0.54 4
hulls 0.57-0.67
seeds USA 1977 0.25 0.08-0.08 0.10-0.11 0.11-0.11
meal Calif. 0.17-0.12
hulls 0.23-0.27
TABLE 1. (Cont'd.)
Residues (mg/kg) at intervals (days) after application
Commodity Country Year Application
rate, kg *
a.i./ha 0 7 14 21 Ref.
seeds USA 1971 0.50 0.19-0.19 0.27-0.34 0.81-0.49
meal Miss. 0.71-0.60
hulls 2.18-4.63 5
seeds USA 1971 0.04-0.07 0.31-0.10 0.38-0.52
meal Miss. 0.64-1.16 5
hulls 2.44-1.33
* All treatments were single applications of a liquid concentrate formulation
Since sunflower meal can constitute up to 20% of the daily ration
of dairy cattle, 15% of the diet of hens and up to 30% of the rations
of other livestock animals, there is no chance that the residues
occurring in sunflower oil used as basic material for manufacturing
compounded animal feed will give rise to levels in products of animal
origin exceeding the levels proposed by the 1976 Joint Meeting
(FAO/WHO 1977 a,b).
RECOMMENDATIONS
In the light of the new and previously available data the maximum
residue limit of 2 mg/kg for sunflower seed (dry) is reaffirmed. The
following maximum residue limits are proposed in addition to those
recommended at previous Meetings.
Commodity MRL, mg/kg
Sunflower meal
(animal feed component) 2
Sunflower oil
(crude and refined) 0.05*
* At or about the limit of determination.
REFERENCES
1 - 5 ICI/Chevron Paraquat: Desiccation of Sunflower (Helianthus
(1978) annua) Unpublished report provided by ICI, Plant
Protection Division, England to the 1978 JMPR.
Calderbank, A. and S.H. Yuen An ion-exchange method for determining
(1965) paraquat residues in food crops. Analyst. 90:
99-106.
See Also:
Toxicological Abbreviations
Paraquat (HSG 51, 1991)
Paraquat (PIM 399)
Paraquat (JMPR Evaluations 2003 Part II Toxicological)
Paraquat (AGP:1970/M/12/1)
Paraquat (WHO Pesticide Residues Series 2)
Paraquat (Pesticide residues in food: 1976 evaluations)
Paraquat (Pesticide residues in food: 1981 evaluations)
Paraquat (Pesticide residues in food: 1982 evaluations)
Paraquat (Pesticide residues in food: 1986 evaluations Part II Toxicology)