Risk is defined as:

Risk in the context of environmental health and safety is fundamentally understood as the potential for harm resulting from exposure to a hazardous substance. Specifically, risk is often quantified using a formula that takes into account the toxicity of the contaminant and the level of exposure that an individual might have to that contaminant.

The correct response explains that risk equals the toxicity of a constituent of concern multiplied by its exposure. Toxicity refers to the degree to which a substance can harm individuals, while exposure assesses how much of that substance a person encounters. By multiplying these two factors, we arrive at a clearer representation of the risk posed to individuals by specific contaminants.

This understanding is essential for evaluating environmental hazards, as it clarifies that both the inherent danger of a substance and the actual encounter with it are crucial to determining overall risk. This approach allows health and safety professionals to assess potential dangers and implement appropriate mitigation strategies.