This testimony before the Subcommittee on Manpower, Compensation, and Health and Safety dealt with the effects of occupational lead (7439921) exposure on human health and the special risks posed by prophylactic use of chelating agents among lead workers. The history of lead as an occupational hazard was reviewed. High exposures have been encountered in welding, metal burning, painting and printing, while lower exposures have been found in gasoline with lead additives. Inorganic lead binds to the red blood cells which transport it throughout the body, allowing it to be stored in the bone, vital organs and tissues. The first criteria document on the issue was published in January of 1973 and recommended an exposure level of 150 micrograms per cubic meter (microg/m3) of air as a time weighted average exposure for a 8 hour workday. This was later revised to approach 50microg/m3. Four categories of health effects were considered in setting these limits: clinical effects of lead exposure, subclinical effects, effects among those most susceptible to lead, and chronic health disorders resulting from long term exposure. A routine use or drugs without adequately controlling exposure in the workplace began to surface as the investigations continued. Chelating agents have been useful in treating acute lead poisoning by removing lead from the body and reducing dangerously high blood lead levels. However, these agents, under repeated use, can harm the kidneys, as does excess exposure to lead.