Holistic risk assessment: an emerging process for environmental decisions.

A holistic risk assessment (HRA) strategy is proposed as an alternative, inclusive paradigm which builds upon the traditional risk assessment process described by the National Academy of Sciences. This proposed process expands beyond the traditional process in that it: (i) includes parallel and integrated assessments for ecological risk and human health risks; (ii) recognizes the presence of competing risks that may arise from implementation of risk management decisions; (iii) is an iterative and nonsequential process that highlights the importance of risk characterization and the need for comparisons; (iv) has focus on presenting a series of risk choices that take into consideration parameters specific to exposed populations and ecosystems; and (v) involves communication as the first step between risk assessors and risk managers, with subsequent communication of the results of the assessment to clients and the public. This HRA strategy is illustrated by a case study on methyl mercury. Specific research is proposed for future improvements in this area.