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manner (to use or not to use a particular agent). Such decisions can be made by considering the exposure scenario that is anticipated in the workplace. The evaluative process describes an approach by which an exposure level that is unlikely to be associated with reproductive and developmental toxicity (the unlikely effect level; UEL) can be estimated. If the workplace scenario is anticipated to result in human exposures sufficiently lower than that estimate, then for policy decisions, the exposure can be regarded as acceptable. If the anticipated human exposure is higher than the estimated UEL, the use of the agent in question can be regarded as unacceptable, and alternative agents can be evaluated or exposure control measures can be put into place.

The process described by the subcommittee requires expertise in the intricacies and relationships of several integrated processes involved in reproduction and development and the exercise of considerable judgment based on the body of scientific knowledge in these areas. That judgment is brought to bear in interpreting data and making decisions concerning the adequacy of available data sets for estimating the potential reproductive and developmental toxicity of agents under specific conditions of exposure. In addition, once there has been a determination of the exposure at which adverse effects are unlikely, judgment is required in the evaluation of other characteristics of the agent or exposure conditions that might make it advisable to alter the estimate for a given workplace scenario.

When the reproductive and developmental risks of a particular exposure cannot be fully characterized, a conservative approach is to assume that such risks exist with exposure conditions below those that produce toxicity for the most sensitive system known for the agent.