Evaluation and use of epidemiological evidence for environmental health risk assessment: WHO guideline document.

Environmental health risk assessment is increasingly being used in the development of environmental health policies, public health decision making, the establishment of environmental regulations, and research planning. The credibility of risk assessment depends, to a large extent, on the strength of the scientific evidence on which it is based. It is, therefore, imperative that the processes and methods used to evaluate the evidence and estimate health risks are clear, explicit, and based on valid epidemiological theory and practice. Epidemiological Evidence for Environmental Health Risk Assessment is a World Health Organization (WHO) guideline document. The primary target audiences of the guidelines are expert review groups that WHO (or other organizations) might convene in the future to evaluate epidemiological evidence on the health effects of environmental factors. These guidelines identify a set of processes and general approaches to assess available epidemiological information in a clear, consistent, and explicit manner. The guidelines should also help in the evaluation of epidemiological studies with respect to their ability to support risk assessment and, consequently, risk management. Conducting expert reviews according to such explicit guidelines would make health risk assessment and subsequent risk management and risk communication processes more readily understood and likely to be accepted by policymakers and the public. It would also make the conclusions reached by reviews more readily acceptable as a basis for future WHO guidelines and other recommendations, and would provide a more rational basis for setting priorities for future research.