ACTIVITY PROFILES OF CARCINOGENICITY DATA - APPLICATION IN HAZARD IDENTIFICATION AND RISK ASSESSMENT

Animal cancer data play a primary role in human risk assessment due to the limited epidemiological data. The current database of test result s from the NCI/NTP rodent bioassays provide valuable information conce rning the carcinogenic potential of hundreds of environmental agents. An approach is presented to reduce and graphically display these data as activity profiles to allow visualization and assessment of tumor re sponse trends across multiple parameters, e.g. species, sex, target si te, and route of exposure. Spreadsheet graphics are used to construct the profiles organized on the multiple parameters of carcinogenicity i n a format that enables comparative analysis among chemicals. Several example applications are described to illustrate the value of activity profiles in hazard identification and risk assessment. The NCI/NTP da ta used in developing this concept are from the Carcinogen Potency Dat abase (CPDB) compiled by Gold et al. (Environ. Health Perspect. 103 (S uppl. 8) (1995) 3-122). Computer links to the underlying details in th e CPDB are maintained such that specific histopathologies at individua l tumor sites, duration of the study, dose-response data, and notes re lated to diet, survival, treatments, and the authors evaluation are av ailable to aid in the assessment process. The profiles display carcino gen potency based on the tumorigenic dose rate 50 (TD50), i.e. the chr onic dose rate that would induce tumors in half of the test animals at the end of their standard lifespan adjusting for spontaneous tumors. The TD50 values provide an index for establishing a relative potency r anking of the chemicals for any specific parameter, such as species or target site. An example ranking of hepatocarcinogens is presented to illustrate relative potencies for chemical analogs. The rank order ind icates that the degree and type of halogenation of alkanes has a direc t bearing on the carcinogenic potency of these compounds. (C) 1997 Els evier Science B.V.