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
THIABENDAZOLE
Explanation
At the 11th Session of the CCPR the view was expressed that the
proposed MRL of 0.1 mg/kg for strawberries was too low. Residue data
from the use of thiabendazole on strawberries as well as for tomatoes,
cucumbers and cherries were received from Denmark. They are assessed
in this addendum.
USE PATTERN
Preharvest Rate, kg/ha
(Denmark) Commodity or Formulation
percent
Strawberry 0.6 40% Emul.
Tomato* 0.10% 40% Emul.
(2 g/plant)
Cherries 0.8 40% Emul.
Cucumber* 0.10% 40% Emul.
(* Glasshouse use)
RESIDUES RESULTING FROM SUPERVISED TRIALS
Data received from Denmark are summarized in Table 1 (Voldum-Claussen,
1979).
Strawberries
The 0.1 MRL for thiabendazole on strawberries was based on a fumigant
treatment in greenhouses and a 3-4 day preharvest interval. Treatment
with 24 g thiabendazole per 100 m2. Under these conditions the
limited data indicated that an MRL of 0.1 mg/kg would not be exceeded.
In Denmark no pre-harvest interval is required. The data indicate
that the outdoor spray treatment results in residues around 0.7 mg/kg
at 1 day and that these residues do not dissipate significantly within
7 days.
Tomato
The 0.1 mg/kg MRL for tomatoes was also based on greenhouse fumigation
in the Netherlands although the rate was 12-18 g/100 m2. The Denmark
application is also an indoor treatment, but is with a spray treatment
with a 0.10% emulsifiable formulation. Again, the residue data in
Table 1 indicate a residue of around 0.7 mg/kg at 1 day and again
there is little dissipation within 7 days. The residue at 1-7 days is
around 2 mg/kg from three applications.
Table 1. Residues from trials with Thiabendazole in Denmark (1979)
Applications of
Crop 40% Emulsion Residues in mg/kg at intervals after applicationa
No. rate
kg ai/ha 4 hrs 1 day 2 days 4 days 7 days
Strawberry 1 0.6 0.68 0.76 0.74 0.60
(0.67-0.70) (0.75-0.78) (0.62-0.86) (0.52-0.69)
Tomatob 1 0.10% 0.64 0.70 0.71 0.54
(0.2 g/plant) (0.58-0.69) (0.69-0.70) (0.58-0.85) (0.51-0.56)
3 0.10% 1.9 2.0 2.1 1.5
(0.2 g/plant) (1.6-2.3) (1.9-2.1) (1.7-2.4) (1.4-1.7)
Cherries 1 0.8 5.3 3.6
(4.7-5.8) (2.9-4.2)
Cucumberb 1 0.10% 0.97 0.80 0.71 0.32
(0.80-1.1) (0.55-1.0) (0.47-0.96) (0.30-0.35)
a. Limit of determination 0.1 mg/kg
b. Glasshouse use
Cherries
No MRL has been proposed for cherries. The data supplied by Denmark
show residues near 6 mg/kg at four hours after the spray treatment
which dissipates to only around 4 mg/kg at seven days.
Cucumber
No MRL has been proposed for thiabendazole on cucumbers. The data in
Table 1 show initial residues of 1 mg/kg one day after a spray
application indoors. Again the residue is slow to dissipate.
FATE OF RESIDUES IN FOOD IN COMMERCE OR AT CONSUMPTION
No additional information was received.
METHODS OF RESIDUE ANALYSIS
No new methods of analysis were received. The analyses of Table 1
were based on extraction with ethyl acetate in alkaline solution,
clean-up by liquid-liquid partitioning and determination by
spectrometry. Limit of determination was 0.10 mg/kg.
APPRAISAL
Residue data on strawberries were received from Denmark to support the
view that the current 0.1 mg/kg MRL is too low. Data from trials with
tomatoes, cherries and cucumbers were also received. The data
indicate that the current 0.1 mg/kg MRLs on strawberries and tomatoes
which were based oil greenhouse fumigation in the Netherlands, are too
low for the practices in Denmark where spray treatments with all
emulsifiable formulation is used.
There are currently no MRLs for thiabendazole on cherries and
cucumbers and available data do not warrant their proposal at this
time.
RECOMMENDATIONS
It is recommended that previously recommended limits for strawberries
and tomatoes be amended as follows:
Commodity Limit
Strawberries 1
Tomatoes 2
FURTHER WORK OR INFORMATION
Desirable
1. Additional residue data and information on use patterns of
thiabendazole on strawberries, tomatoes, cherries and cucumbers
from countries other than Denmark and the Netherlands.
2. Information listed as desirable in the 1977 Evaluations.
REFERENCES
Voldum-Clausen, K. - Experiments on Pesticide Residues. No. S. 415,
416, 419 and 420. (1979) Unpublished, Restricted, Ministry of the
Environment, National Food Institute, Division of Pesticides and
Contaminants, Morkhoj Bygade 19. DY-2860 Soborg, Denmark.
See Also:
Toxicological Abbreviations
Thiabendazole (WHO Food Additives Series 39)
Thiabendazole (AGP:1970/M/12/1)
Thiabendazole (WHO Pesticide Residues Series 1)
Thiabendazole (WHO Pesticide Residues Series 2)
Thiabendazole (WHO Pesticide Residues Series 5)
Thiabendazole (Pesticide residues in food: 1977 evaluations)
Thiabendazole (Pesticide residues in food: 1981 evaluations)