This testimony before the Subcommittee on Manpower, Compensation, and Health and Safety presented the knowledge gained by NIOSH and other units of the Centers for Disease Control following the tragedy in the Commonwealth of Virginia concerning the introduction of kepone (143500) into the environment. When visiting the facility, gross contamination of kepone on the walkways, floors, walls, and overhead structures was observed. Special work clothing was not generally worn and clothing contaminated with kepone was frequently worn home. The employees frequently ate on the job. While a few face masks were provided, these were not used regularly. Of the 113 present and former employees examined, over half of them exhibited symptoms of kepone poisoning including nervousness, weight loss, chest and joint pains, tremor, difficulty in walking, and skin rash. All 32 current employees had detectable levels of kepone in their blood. Only the efforts of two physicians, one at the site and one at the Center for Disease Control (CDC), brought about a closure of the facility on July 26, 1975 based on the blood levels of kepone in one worker. On August 8, a CDC epidemiologist visited several workers, families and community members. Preliminary evidence now exists that kepone is a carcinogen and the recommended exposure level is not greater than 1 microgram/cubic meter of breathing zone air for a 10 hour day, 40 hour week, over a working lifetime. The recommendations made to OSHA from these studies were included in the report. The 36 companies believed to be formulators of insecticides containing kepone have been notified of the hazards and recommendations for controlling them. The larger issue of uncontrolled exposures to field workers, chemical workers, formulators, and the like to hazardous pesticides was discussed.