Chemical Risk Assessment as Used in Setting Regulatory Levels or Standards

1 Chemical Risk Assessment as Used in Setting Regulatory Levels or Standards 

Bernard K Gadagbui, Lynne T Haber and Michael L Dourson 

Risk assessment is a process where the magnitude of a specific risk is characterized so that decision-makers can conclude whether the potential hazard is sufficiently great that it needs to be managed or regulated, reduced or removed. The National Research Council (NRC, 1983) of the National Academy of Sciences (NAS) first described the process of human health risk assessment, with an update in 1994 and 1996, as a four-component paradigm (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization), with risk communication as a fifth area of study. The first four components are described briefly below. 

Hazard identification explores potential concerns about a chemical. It involves an evaluation of the nature, quality, and relevance of scientific data on the specific chemical, the characteristics and relevance of the experimental routes of exposure, and the nature and significance of the observed effects. In this step, scientific studies are reviewed to determine if exposure to an agent could cause increased incidence of adverse health effects (noncancer or cancer effects) in humans, and to identify which effects the chemical can cause. 

For noncancer toxicity, the process includes an evaluation of the target organ or critical effects (i.e., the first adverse effect or its known precursor that occurs as the dose rate increases). In some cases, one needs to determine whether an effect is adverse or not. The choice of critical effect in the hazard identification process for noncancer toxicity is used as a basis for the dose-response assessment. 

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