New methodologies for assessment of risk from pesticide residues

Government officials have a responsibility to protect their populace and the environment from harm. Accordingly, they are bound to consider the potential impact of pesticide residues in food upon public health. One tool available to officials is dietary risk assessment. Risk assessment consists of an estimate of exposure compared to a measure of toxicity. Dietary exposure is simply estimated as the product of the amount of food that is consumed and the residue concentration on the food. Initial worst-case risk assessments often indicate that risk levels are unacceptably high. A dilemma facing government officials, who must make decisions based upon such risk assessments, is that a worst case risk assessment provides little useful information. In some cases, the initial risk assessment is acceptable, and because the assumptions of the assessment are so extreme, the official is virtually assured that the compound is safe. However, if the initial risk assessment indicates that risk is unacceptable, the official is faced with a number that appears to signify something about risk, but in reality is misleading. In such cases, refined procedures are necessary to develop more realistic estimates of risk. Realistic risk assessments typically demonstrate that risk does not exceed acceptable levels. The refinements can take the form of more sophisticated methods for estimating exposure, such as probabilistic modelling. However, the most prevalent types of refinements have to do with better data for food consumption and residue concentration. Residues usually are not found, even in the most extensive residue monitoring programs. Such residues as are detected typically are quite low and seldom reach Maximum Residue Limit levels. Consequently, acceptable risk levels that are calculated with robust data and scientifically rigorous techniques are trustworthy.