The Pollution Hazard Assessment System Version 20: Documentation and Users Manual
1991
Small, Mitchell J.
The Pollution Hazard Assessment System (PHAS) is a suite of programs used to perform exposure assessments for pollutants in soils or surface to ground water at known or suspected hazardous waste sites. PHAS can assist in planning, data acquisition and exposure assessment exercises of remedial investigations. It includes chemical-related data estimation subroutines (CRDES) to provide approximations when experimental values are not available. This document describes the present version, PHAS20. The general exposure assessment problem is discussed to promote an understanding of the system's response to the problem, and its relationship to U.S. Environmental Protection Agency risk assessment guidance. PHAS20 conceptually follows the Preliminary Pollutant Limit Value (PPLV) approach. The approach involves these steps: (1) determine pollutants of concern; (2) define land use scenarios, and for each scenario, specify component exposure pathways; (3) Develop equation(s) for each pathway that relates human intake of a substance to the substance concentration is soils; (4) Collect data; (5) For pollutant or toxic hazards and scenario, use developed equations to compute pathway soil concentration limits corresponding to acceptable intake and; (6) Determine if non public health considerations, such as aquatic toxicity or phytotoxic effects, might be more restrictive than public health considerations.
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