Risk Assessment : Present and Future

Risk assessment is a scientific endeavour to evaluate and estimate the exposure to a substance and its consequent adverse health effects by the use of the available scientific information. The four phases of the risk assessment include hazard identification, exposure estimation, doseresponse assessment and risk characterization. Recently, risk management and risk communication have been added as its final components. At present, however, methods for identifying toxicants and exposed individuals and populations, models for inferring human health effects from animal studies, techniques for estimating risks and predicting health effects with few data are all in need of improvement or development. Fortunately, remarkable advances in biotoxicology and molecular biology have promoted new understandings in the mechanism of disease. Incorporation of these new data moved the evaluation closer to the goal of estimating actual human risks. Recently developed physiologically-based pharmacokinetic models for the estimation of active chemical levels at critical organs and their conjugation with biologically-based pharmacodynamic models of the process of carcinogenesis seem to be not only an essential part of a rational approach to quantitative cancer risk assessment, but also raise fundamental questions about the nature of the events leading to malignancy. These scientific progress will develop sound risk assessment, dissolve the wide divergency in regulatory decisions of agencies in different countries, and lead to better health protection.