Ranking of carcinogenic potency using a relative potency approach.

Protocols for long-term carcinogen bioassays have become highly refined. The ability to interpret these bioassay results beyond the experimental setting, however, has not improved commensurately. As a consequence, society is still faced with the fact that data derived in these bioassays reflect highly specific experimental conditions which are vastly different from environmental exposures of the freely roaming, outbred human. The scientific community has responded with a "collective wisdom" approach by using expert committees to interpret bioassay evidence. This committee approach is believed to be successful in protecting human health, but the list of suspected carcinogens is growing faster than the expert committees can respond. We have developed a relative potency framework for ranking the hazards represented by potential human carcinogens. The results demonstrate a rank ordering of a variety of compounds which is independent of the reference compound used to standardize the information. The philosophic basis of the approach may facilitate expert risk assessment systems development because it: (1) complements and supports "expert committee" data selection; (2) has a simple set of rules and does not require mathematical modeling; (3) requires no special situation judgments; and (4) is suitable for use with electronic data bases.