The American Conference of Governmental Industrial Hygienists’ (ACGIH) Threshold Limit Values (TLVs) refer to a set of guidelines regarding the airborne concentrations of chemical substances that workers can be safely exposed to over their working lifetime. The ACGIH developed TLVs as a tool for industrial hygienists to make informed decisions about chemical exposure in the workplace. Workers can inhale airborne chemicals as gas, vapors, or aerosols. Although TLVs are guidelines, not regulations, authorities like the Occupational Safety and Health Administration (OSHA) recommend and refer to them.
There are TLVs for over 600 chemical substances and physical agents, divided into four categories: time-weighted average (TWA); short-term exposure limit (STEL); surface limit (SL); and ceiling (C). Chemicals existing at concentrations less than or equal to a TLV can be understood as presenting no adverse health effects, while a concentration that exceeds the TLV value can be interpreted as a health hazard. However, chemicals with the same TLV value do not necessarily have the same toxicological effects or biologic potency.
The American Conference of Governmental Industrial Hygienists (ACGIH) is a nonprofit corporation composed of industrial hygienists and professionals who work to advance health and safety in the workplace. The ACGIH has also developed over thirty Biological Exposure Indices (BEIs) for selected chemicals. BEIs are another measure used to assess exposure to chemicals in the workplace. The ACGIH members who develop TLVs and BEIs are independent experts in occupational health. Their determinations are representative of the scientific consensus regarding safe levels of exposure to chemical and physical agents found in the workplace.1