Risk Analysis and Mitigation Flashcards

A facility stores large quantities of chlorine gas. Which federal regulatory program requires the facility to conduct an Offsite Consequence Analysis (OCA)?

Answer: EPA's Risk Management Program (RMP) under Clean Air Act Section 112(r)

EPA's RMP rule requires facilities with regulated substances above threshold quantities to conduct OCAs modeling worst-case and alternative release scenarios that could affect the public.

What is 'bioremediation' as a risk mitigation technology, and what is its primary limitation?

Answer: Use of microorganisms to degrade contaminants in situ; limited by site-specific geochemical conditions that may inhibit microbial activity

Bioremediation harnesses microbial metabolism to break down contaminants, but its effectiveness depends on nutrient availability, pH, temperature, electron acceptor conditions, and contaminant bioavailability.

In the context of risk assessment, what is 'bioavailability' and why does it matter?

Answer: The fraction of an ingested or inhaled contaminant that is absorbed and reaches systemic circulation

Bioavailability is the fraction of an exposure dose that is actually absorbed into the body; using site-specific bioavailability data can reduce overly conservative risk estimates based on 100% absorption assumptions.

A risk assessor finds that ambient air concentrations of benzene at a site exceed risk-based screening levels. What is the appropriate next step under a tiered risk assessment approach?

Answer: Proceed to a more detailed, site-specific assessment using measured exposure data before concluding cleanup is required

Screening-level exceedances trigger further evaluation, not automatic remediation; a refined site-specific risk assessment using actual exposure data refines whether true risk exceeds action levels.

Which of the following is the best definition of 'cumulative risk' in environmental health assessment?

Answer: The combined risk from multiple stressors (chemical, physical, biological, social) to which a population is exposed over time

Cumulative risk assessment considers the combined burden of multiple chemical and non-chemical stressors, often with particular attention to vulnerable and disproportionately exposed communities.

What is the purpose of a 'fate and transport' analysis in site risk assessment?

Answer: To predict how contaminants move and transform in environmental media from source to receptor

Fate and transport modeling predicts the migration, dilution, transformation, and degradation of contaminants through soil, groundwater, surface water, and air, linking sources to receptors in the CSM.

Under the National Contingency Plan (NCP), what is the primary criterion that must be met for a remedial action to be considered 'protective of human health and the environment'?

Answer: Residual risks after remediation must fall within the 10⁻⁶ to 10⁻⁴ cancer risk range and HI ≤ 1 for non-cancer endpoints

The NCP requires that remedial actions achieve residual cancer risks within the 10⁻⁶–10⁻⁴ range and hazard indices at or below 1 for non-cancer effects to be deemed protective.