The<unk>  <unk>  is believed to be a level to which a worker can be exposed per shift in the worktime without adverse effects. Strictly speaking,<unk>  is a reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH).<unk> s issued by the ACGIH are the most widely accepted occupational exposure<unk> s both in the United States and most other countries. However, it is sometimes loosely used to refer to other similar concepts used in occupational health and toxicology, such as acceptable daily intake (ADI) and tolerable daily intake (TDI). Concepts such as<unk> , ADI, and TDI can be compared to the no-observed-adverse-effect level (NOAEL) in animal testing, but whereas a NOAEL can be established experimentally during a short period,<unk> , ADI, and TDI apply to human beings over a lifetime and thus are harder to test empirically and are usually set at lower levels.<unk> s, along with biological exposure indices (BEIs), are published annually by the ACGIH. The<unk>  is an estimate based on the known toxicity in humans or animals of a given chemical substance, and the reliability and accuracy of the latest sampling and analytical methods. It is not a static definition since new research can often modify the risk assessment of substances and new laboratory or instrumental analysis methods can improve analytical detection<unk> s. The<unk>  is a recommendation by ACGIH, with only a guideline status. As such, it should not be confused with exposure<unk> s having a regulatory status, like those published and enforced by the Occupational Safety and Health Administration (OSHA). The OSHA regulatory exposure<unk> s permissible exposure<unk> s (PELs) published in 29CFR 1910.1000 Table Z1 are based on recommendations made by the ACGIH in 1968, although other exposure<unk> s were adopted more recently. Many OSHA exposure<unk> s are not considered by the industrial hygiene community to be sufficiently protective levels since the toxicological basis for most<unk> s have not been updated since the 1960s. The National Institute for Occupational Safety and Health (NIOSH) publishes recommended exposure<unk> s (RELs) which OSHA takes into consideration when promulgating new regulatory exposure<unk> s.
Threshold limit value
Indicative limit value
Absolute threshold
Relative value unit
Mortality rate
Minimal important difference
Inter-rater reliability
Risk difference