Implementation of EPA Revised Cancer Assessment Guidelines: Incorporation of Mechanistic and Pharmacokinetic Data

A workshop entitled "Implementation of EPA Revised Cancer AssessmentGuidelines: Incorporation of Mechanistic and PharmacokineticData" was held in Anaheim, California, in 1996 at the 35th AnnualMeeting of the Society of Toxicology (SOT). This workshop wasjointly sponsored by the Carcinogenesis, Risk Assessment, andVeterinary Specialty Sections of the SOT. The thrust of theworkshop was to discuss the scientific basis for the revisionsto the EPA Guidelines for cancer assessment and EPA's plansfor their implementation. This is the first revision to theoriginal EPA guidelines which have been in use by EPA since1986. The principal revisions are intended to provide a frameworkfor an increased ability to incorporate biological data intothe risk assessment process. Two cases were presented, for chloroformand trichloroethylene, that demonstrated the use of the revisedguidelines for specific cancer risk assessments. Using thesenew guidelines, nonlinear margin of exposure analyses were proposedfor these chemicals instead of the linearized multistage modelpreviously used by the EPA as the default method. The workshopparticipants generally applauded the planned revisions to theEPA guidelines. For the most part, they considered that therevised guidelines represented a positive step which shouldallow for and encourage the use of biological information inthe conduct of cancer risk assessments. Several participantscautioned however that the major problem with cancer risk assessmentswould continue to be the inadequacy of available data on whichto conduct more scientific risk assessments.