Monitoring for precursors of health impairment from toxic agents

It is essential that one be able to diagnose when disorders are caused by drugs and toxic agents. It is also essential that scientists strive toward the ultimate goal of preventing such disorders. To this end, it is necessary to evaluate laboratory procedures for their capability to detect changes which precede disorders of health impairment. To accomplish this, some knowledge of the relationship between the exposure to a chemical agent and the effect owing to that exposure is required. The complexities of the dose-effect relationship are discussed with regard to the estimation of exposure, the effect owing to the exposure and the population exposed to the chemical agent.