RESIDUE AND ANALYTICAL ASPECTS
Residue aspects of aldicarb were last evaluated in 1994 within the CCPR periodic review programme. In response to the request of the 1994 Meeting extensive new information was provided on residues resulting from the currently recommended uses on bananas and potatoes, the stability of residues in potatoes during commercial storage, the effect of processing on residues in potatoes, and on the revised GAP for potatoes in the USA. The Meeting was informed about ongoing trial programmes on bananas and potatoes.
The trials were with granular formulations of aldicarb. The samples were mainly analyzed by HPLC methods which determined aldicarb, its sulfoxide and its sulfone individually. In some cases the residues were oxidized to, and determined as, the sulfone. The typical limit of determination was about 0.01-0.02 mg/kg for each residue component. The main residue in bananas and potatoes was aldicarb sulfoxide.
In US trials residues were measured in over 6000 individual potato tubers to determine the effects of the mode of application, irrigation method and climatic conditions on the magnitude and distribution of residues in the middle and end sections of the rows. The data showed that the residues in individual tubers could be much higher than in composite samples on which the MRL is based. Since the between-fields variance of residue levels was much larger than the within-field variance, the Meeting could estimate the maximum residue levels on the basis of the averages of residues found in the sites.
The Meeting could not evaluate the results of South African trials as they were provided only in a summarized form.
The available information enabled the Meeting to estimate a maximum residue level and STMR level for potatoes, and to estimate the maximum residues likely to occur in individual potato tubers. STMRs were also estimated for several potato products. The data were insufficient to estimate a maximum residue level for bananas.
FURTHER WORK OR INFORMATION
Desirable
1. Results of supervised trials according to maximum Spanish and South African GAP on potatoes.
2. Residue data on whole bananas and banana pulp reflecting current GAP.
3. Data on the effect of boiling (cooking) on aldicarb residues in potatoes.
