Summary: Concern is rising about toxicants that can damage the human reproduction system and fetal development. The societal impacts of these substances include the large number of infants born with birth defects and the costs of their lifelong care, a high U.S. infant mortality rate compared to that of other developed countries, and the growing number of children with basic learning disabilities. The causes of 60 percent of these and other reproductive and developmental diseases are currently unknown; the exact percentage caused by environmental exposures may not be known for decades. Prevention is preferable to treatment, and chemical exposures are probably the most preventable of the known causes. Because the network of federal programs authorized to control exposure to toxicants has the major responsibility to prevent environmentally caused disease, GAO studied the extent and sufficiency of federal regulations in this area. Key findings of the study were that (1) federal regulatory agencies have not consistently applied the scientific knowledge that exists to the control of the reproductive and developmental hazards of environmental chemicals but have instead focused on cancer and acute toxicity; (2) of the 10 programs GAO reviewed, the regulatory achievement on 30 widely acknowledged reproductive and developmental hazards falls short of the professed standards of these very programs and those of experts; and (3) the sufficiency of protection afforded by the current regulation of reproductive and developmental hazards is in doubt, both for the 30 GAO studied and quite possibly for others. GAO summarized this report in testimony before Congress; see: Reproductive and Developmental Hazards: Regulatory Actions Provide Uncertain Protection, by Eleanor Chelimsky, Assistant Comptroller General for Program Evaluation and Methodology, before the Senate Committee on Intergovernmental Affairs. GAO/T-PEMD-92-1, Oct. 2 (37 pages).