Ecological Risk Assessment

Ecological risk assessment (ERA) estimates the likelihood and magnitude of adverse effects on ecosystems from chemical, physical, or biological stressors. The standard framework runs problem formulation, then exposure assessment and effects assessment, then risk characterization. For chemicals it compares a predicted environmental concentration (PEC) against a predicted no-effect concentration (PNEC); the resulting risk quotient (PEC/PNEC) above 1 indicates unacceptable risk and triggers refinement or risk management. EU REACH and the US EPA both mandate ERA for chemical authorization, and the tiered approach moves from conservative screening to higher-tier modeling such as species sensitivity distributions.