Humans live in a chemical environment and inhale, ingest, or absorb from the skin many of these chemicals. Toxicology is concerned with the deleterious effects of these chemical agents on all living systems. In the biomedical area, however, the toxicologist is primarily concerned with adverse effects in humans resulting from exposure to drugs and other chemicals as well as the demonstration of safety or hazard associated with their use.
Occupational toxicology deals with the chemicals found in the workplace. The major emphasis of occupational toxicology is to identify the agents of concern, identify the acute and chronic diseases that they cause, define the conditions under which they may be used safely, and prevent absorption of harmful amounts of these chemicals. Occupational toxicologists may also define and carry out programs for the surveillance of exposed workers and the environment in which they work. Regulatory limits and voluntary guidelines have been elaborated to establish safe ambient air concentrations for many chemicals found in the workplace. Governmental and supragovernmental bodies throughout the world have generated workplace health and safety rules, including short-and long-term exposure limits for workers. These permissible exposure limits (PELS) have the power of law. Copies of the United States Occupational Safety and Health Administration (OSHA) standards may be found on OSHA's website at http://www.osha.gov. Copies of the United States Mine Safety and Health Administration (MSHA) standards may be found at http://www.msha.gov.
Voluntary organizations, such as the American Conference of Governmental Industrial Hygienists (ACGIH), periodically prepare lists of recommended threshold limit values (TLVs) for many chemicals. These guidelines are periodically updated, but regulatory imperatives in the United States are not updated except under certain extraordinary circumstances. These TLV guidelines are useful as reference points in the evaluation of potential workplace exposures. Copies of current TLV lists may be obtained from the ACGIH at http://www.acgih.org.
Environmental toxicology deals with the potentially deleterious impact of chemicals, present as pollutants of the environment, on living organisms. The term environment includes all the surroundings of an individual organism, but particularly the air, soil, and water. Although humans are considered a target species of particular interest, other species are of considerable importance as potential biologic targets.
Air pollution is a product of industrialization, technologic development, and increased urbanization. Humans may also be exposed to chemicals used in the agricultural environment as pesticides or in food processing that may persist as residues or ingredients in food products. Air contaminants are regulated in the United States by the Environmental Protection Agency (EPA) based on both health and esthetic considerations. Tables of regulated air contaminants and other regulatory issues that relate to air contaminants in the United States may be found at http://www.epa.gov. Many states also have individual air contaminant regulations that may be more rigorous than those of the EPA. Many other nations and some ...