EVALUATION OF THE HAZARD QUOTIENT METHOD FOR RISK ASSESSMENT OF SELENIUM

Environmental contamination with selenium from industrial and agricult ural sources has poisoned fish and wildlife at several locations in th e United States, Monitoring and risk assessment activities are current ly being conducted by many state and Federal agencies, The U.S. Enviro nmental Protection Agency (EPA) recommends a hazard quotient (HQ) meth od (waterborne concentration divided by the national water quality cri terion) to assess the toxic threat of individual waterborne elements, including selenium, An evaluation of the EPA HQ method was conducted b y comparing it to a recently published protocol (Protocol) for seleniu m assessment. Hazard estimates obtained using HQ were found to be inva lid because the EPA water quality criterion is outdated, and the proce dure uses mean rather than maximum waterborne concentrations, The HQ m ethod seriously underestimates hazard and could lead to risk managemen t decisions that would not protect fish and wildlife from selenium tox icity, The Protocol method provides an accurate assessment because it evaluates hazard by examining multiple exposure pathways on a site-spe cific basis, Until a revised (lowered) national water quality criterio n is available, the EPA HQ method should not be used for selenium, Eve n then, with the availability of the Protocol, HQ analysis should be r estricted to data sets where water is the primary or sole source of in formation on environmental concentrations of selenium. (C) 1996 Academ ic Press, Inc.