ALTERNATIVES FOR A RISK ASSESSMENT ON CHRONIC NONCANCER EFFECTS FROM ORAL-EXPOSURE TO TRICHLOROETHYLENE

Changes in methodologies are presently occurring for dose-response ass essment in noncancer and cancer risk assessments. The benchmark dose ( BMD) method is an alternative to the no-observed-adverse-effect level (NOAEL)/uncertainty factor (UF) approach for development of toxicity v alues, A comparison of these two methods was undertaken using trichlor oethylene, an important industrial chemical and environmental contamin ant, This analysis considered liver effects, kidney toxicity, and deve lopmental defects, A range of toxicity values was obtained using the t wo methods from which acceptable drinking water concentrations were es timated: 1000-10,000 ppb for liver effects, 1750 ppb hom kidney toxici ty, and 1000-10,000 ppb from developmental defects of the eye, These v alues are all higher than those based upon cancer as the critical endp oint, This analysis highlighted the strengths of the BMD approach in t he presence of adequate dose-response data, but it also suggested that guidance is required for addressing inadequate dose-response data The selection of UF and critical studies were identified as areas that ha ve a large impact upon the final dose-response values, sometimes great er than the variations arising from using the BMD rather than the NOAE L. (C) 1996 Academic Press, Inc