Screening site contamination usina pathway exposure factors: Fid-Bau Portal

Screening site contamination usina pathway exposure factors

Hixson, Jane / Dryden, Cathy / Hise, Wallace

Radian Corporation conducted an investigation of 29 waste sites at an air force base in New Mexico in partial fulfillment of the RCRA operating permit requirements for the facility. The contract required that the investigation be conducted under the Installation Restoration Program (IRP/CERCLA). In an effort to satisfy both RCRA and CERCLA requirements, a hybrid approach was taken for the risk assessment. Site contaminants ranged from petroleum and unconventional fuels to solvents, pesticides, and PCBs. A screening method was developed to classify the level of contamination at each of the 29 sites based on soil and groundwater sampling results. Under this method, sites were classified as “dirty,”; “clean,”; or “borderline.”; Dirty sites did not require a full‐scale risk assessment because some form of remedial action would be necessary. However, clean sites and borderline sites required a full‐scale risk assessment. For clean sites, the risk assessment served as justification for no further action; for borderline sites, the risk assessment determined whether or not remedial action would be required. The screening method used previously developed multipathway and multimedia models for estimating potential human exposure to environmental contaminants in the air, water, and soil through inhalation, ingestion, and dermal contact routes. Pathway exposure factors (PEFs), which combined information on human physiology, behavior patterns, and models of environmental transport, were used to determine the relationship between the concentration of environmental contaminants and human exposure. The PEF converts concentrations in environmental media to lifetime‐equivalent chronic daily intakes (CDI). Three exposure pathways contributing the greatest proportion of the risk were considered for screening these sites: (1) incidental ingestion of soil; (2) dermal contact with soil; and (3) ingestion of water. This project demonstrated that a screening approach could be used effectively to limit the number of full‐scale risk assessments required for a multisite investigation.