Risk Assessment for Biological Stressors

Abstract

In general, environmental stressors are chemical, physical, or biological agents capable of causing adverse effects on human health, safety, or the environment. Historically, the field of environmental risk assessment has focused primarily on the human health effects of chemical toxicants. The environmental risks posed by physical stressors, such as radiation, flood, drought, and fire, have also been assessed to a significant extent. Formal, quantitative risk assessment for biological stressors, however, is a nascent field of scientific analysis. Although the bounds of scientific uncertainty for risk assessment of chemical contaminants may span multiple orders of magnitude, the underlying principles, methods, data, and conventions for chemical risk assessment are far more developed than are those for the assessment of biological stressors. The main difference between chemical and biological stressors are that biological organisms: (a) grow, reproduce, and may multiply; (b) disperse both actively and passively, often in “jumps” that are hard to predict; (c) interact with ecosystems in ways that can be complex and are hard, if not impossible, to predict; and (d) evolve, and this evolution is largely random [1]. Some biological hazards combine elements of both biological and chemical risks. Staphylococcal food poisoning, for example, is not an infection but results from the production of a heat-stable chemical toxin by Staphylococcus aureus. The quantity of the toxin present in food, however, is a function of staphylococcal growth. To appreciate the novel risk assessment challenges posed by biological stressors, consider that chemical contaminants present below analytical detection limits typically pose negligible risks.

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