Integrated environmental risk characterisation

Risk characterisation is the final phase of the health risk assessment process. It integrates the three phases: Hazard Identification, Dose-Response Assessment, and Exposure Assessment. This phase determines the probability of an adverse effect to a human population by a toxic substance and outlines permissible exposure levels from which standards of exposure are set. Characterizing Risk for Non-carcinogens The first step is to consider the Admissible Daily intake (ADI) as was defined in the dose-response phase of the risk assessment, compared to the maximum exposure occurring within the target population, and which is calculated in the exposure assessment phase. There are far too many uncertainties associated with our knowledge of the effects of substances and individual human sensitivities. Characterizing Risk for Carcinogens Considering that carcinogens are considered to pose a risk at any dose and the probability of developing cancer would increase with dose, we can state that the probability can range from being negligibly low at low dose ranges or unacceptably high at high dose ranges. Currently the risk value of one in a million is considered an insignificant risk and is used as a maximum value for defining permissible environmental concentrations. The Margin of Exposure (MoE) and the Threshold of Toxicological Concern (TTC) will also be addressed. Combined Exposure There is increasing need to address the potential risks of combined exposures to multiple residues from pesticides in the diet. The available evidence suggests that the main concern is from dose addition of those compounds that act by the same mode of action. The possibility of synergy needs to be addressed on a case-by-case basis, where there is a biologically plausible hypothesis that it may occur at the levels of residues occurring in the diet. Cumulative risk assessment is a resource-intense activity and hence a tiered approach to both toxicological evaluation and intake estimation is recommended, and the European Food Safety Authority (EFSA) has recently published such a proposal.