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Using Science to Improve Risk Assessment
Reducing uncertainty in risk assessments is a major goal of scientists in NCEA. There are many uncertainties in risk assessments because of limitations in the available data and because of the complex interactions between the sources and environmental concentrations of contaminants, the dose received at the site within a person where the effect is induced, and variability in people's responses. These uncertainties result in the use of default assumptions, simplified approaches, and uncertainty factors. Though designed to be protective of human health, assumptions and uncertainty factors may overestimate the risk and result in overly stringent standards and unnecessarily burdensome costs. Conversely, oversimplifying the risk assessment may underestimate risks, particularly for some groups such as children or the elderly; errors of this type present a different type of unacceptable cost.
To overcome these challenges, NCEA scientists work to develop and improve the models, assumptions, and extrapolations used in risk assessments. They also perform research to evaluate different approaches for conducting risk assessments and the implication of each approach. Recent work in this area includes an evaluation of the benchmark-dose approach for non-cancer risk assessments and the additivity-hazard-index approach for assessing risks posed by mixtures of chemicals.
The work of NCEA scientists has yielded a large suite of guidelines and tools that assist those responsible for assessing and managing risks. These are available through the following links:
