In the first case, anyone who has ever attempted a cumulative risk assessment knows that when you try to evaluate aggregate effects on a population from a diversity of environmental stressors, the discussion rapidly moves away from the science because the science simply isn’t there. The process necessarily becomes qualitative and attitudes, biases, and perceptions play a prominent role in the final outcome. We therefore have to strengthen the scientific underpinnings that are the foundation for realistic assessment of cumulative risks.

Equally important, though rarely talked about, is the need to develop new tools and approaches for integrating cumulative risk information into environmental decisions. Moreover, we must train risk managers to appreciate the subtleties and nuances of cumulative risk assessment and to use these new methods to make sound choices that are protective of environmental health for current and future generations.

Finally, we face a fifth and overarching challenge: the need to make better environmental health decisions, where “better” means effective (actions achieve desired results), efficient (results are achieved at reasonable cost), and equitable (those who benefit also bear the costs, and vice versa). The complexity and expense of dealing with twenty first-century environmental health problems, like global climate change, make it essential that decisions are sustainable. The concept of “sustainability” accentuates simultaneous attainment of three complementary goals: environmental protection (safeguard and restore the natural environment); economic prosperity (improve the quality of human life); and social justice (ensure equitable distribution of costs and benefits). The ultimate goal of environmental health decisions must be to meet the needs of the present without compromising the ability of future generations to meet their own needs.