The maximum exposure to a biologically active physical or chemical agent that is allowed during an 8-hour period (a workday) in a population of workers, or during a 24-hour period in the general population, which does not appear to cause appreciable harm, whether immediate or delayed for any period, in the target population. (From Lewis Dictionary of Toxicology, 1st ed)
Fluorohydrocarbons -- Threshold limit values : Submarine exposure guidance levels for selected hydrofluorocarbons : HFC-236fa, HFC-23, and HFC-404a / Subcommittee on Exposure Guidance Levels for Selected Hydrofluorocarbons, Committee on Toxicology, Board on Environmental Studies and Toxicology, Commission on Life Sciences, National Research Council
Threshold limit values (Industrial toxicology) -- Australia. : Exposure standards for atmospheric contaminants in the occupational environment : guidance note on the interpretation of exposure standards for atmospheric contaminants in the occupational environment : adopted national exposure standards for atmospheric contaminants in the occupational environment : proposed national exposure standards for atmospheric contaminants in the occupational environment / National Occupational Health and Safety Commission