At the request of the Meeting, WHO (GEMS/Food) calculated the predicted intakes of residues of the pesticides on the agenda of the Joint Meeting using the methods described in Guidelines for Predicting Dietary Intake of Pesticide Residues (WHO, 1989) as revised by Recommendations for the revision of the guidelines for predicting dietary intake of pesticide residues (WHO/FNU/FOS/95.11).
Theoretical Maximum Daily Intakes (TMDIs) and, when information was available, International Estimated Daily Intakes (IEDIs) were calculated for those pesticides considered by the JMPR on the basis of the ADIs and MRLs proposed by the Meeting and existing and draft MRLs in the Codex system. For calculating IEDIs, Supervised Trials Median Residue (STMR) levels were available for newly evaluated pesticides and for some pesticide/commodity combinations of previously considered pesticides. In a few cases, processing data were also available for refining the assessments of dietary exposure.
The TMDI and/or the IEDI did not exceed the ADI for the following compounds:
acephate, aldicarb, bifenthrin, 2,4-D, diazinon, DDT, fenarimol, flumethrin, haloxyfop, maleic hydrazide, methamidophos, propoxur, tebufenozide, and teflubenzuron.
The TMDI exceeded the ADI for the following compounds, but information on STMR levels and processing factors must be reviewed before IEDIs can be calculated:
carbaryl, carbofuran, dimethoate, mevinphos, and phorate.
For thiram and ziram, the assessment covered the total intake of all dithiocarbamates, including mancozeb, maneb, metiram, propineb and zineb, and took into account the relative ADIs, molecular mass adjustments for residues expressed as carbon disulfide, and the relevance of individual dithiocarbamate compounds for each MRL. While the calculated IEDI for dithiocarbamates exceeded the ADI for three of the five regional diets considered, STMR levels were available for only a few pesticide/commodity combinations. Further refinement of the intake assessment will therefore be required. The Meeting agreed that a general method should be developed, with the inclusion of worked examples, for estimating the dietary intake of residues of pesticides that have common mechanisms of toxicity.
The dietary intake was not estimated for chlorfenvinphos because it was recommended that all existing MRLs should be withdrawn, or for ferbam because no MRLs were recommended.
It should be noted that the calculated TMDIs grossly over-estimate the true intake of pesticide residues. It should, therefore, not be concluded that the MRLs recommended by the Meeting are unacceptable when the TMDI exceeds the ADI. Calculations of TMDIs can be used as a screening tool, and the IEDI should be calculated when data are available.