Exposure Elements in Oil Spill Risk and Natural Resource Damage Assessments: A Review

Abstract

The use of the ecological risk assessment (ERA) framework for assessing effects of oil spills is applicable to the injury assessment component of natural resource damage assessment (NRDA). Central to the ERA process is the assessment of exposure, the critical component linking the release of oil to the assessment of effects. Exposure of biological receptors to the toxic fractions of spilled oil, usually considered the polycyclic aromatic hydrocarbons (PAH), requires carefully designed and implemented assessment studies, which are periodically refocused on various environmental pathways and the various biological receptors of concern over the life history of an oil spill from initial release to recovery. As important is the detailed assessment of the exposure regime in the absence of a spill (i.e., the baseline or background exposure). A release of petroleum may not, in itself, equate to an effect on a natural resource. The presence of residual petroleum hydrocarbons does not imply either availability to living organisms or injury to a biological resource. Precise and accurate chemical concentration and compositional data for 2–6 ringed PAHs and alkylated homologues are the key toxicologically important chemical components that are central to the exposure assessment. These principles are illustrated in several oil spill case studies.