In occupational safety and health, biomonitoring may be done for reasons of regulatory compliance, workplace health surveillance and research, confirming effectiveness of hazard controls, or as a component of occupational risk assessment.  It can also be used to reconstruct exposures following acute or accidental events, and to assess the effectiveness of personal protective equipment.  It is useful for dermal exposures, for which sampling methods are often not readily available, and for finding unexpected exposures or routes.  There are also biomarkers not just for chemical hazards, but also other types such as noise and stress.  Occupational health differs from environmental health in that the former has smaller number of exposed individuals, but with a wider range of exposure levels.
Biomonitoring is complementary to exposure monitoring in that it measures the internal dose of a toxicant within the body rather than its concentration outside the body, with the advantage that it confirms whether not only exposure but uptake has actually occurred.  It also takes into account differences in metabolism, physical exertion, and mixtures of toxicants between individuals that affect the internal dose.  It can be done in an individual or collective manner.
A major use of occupational toxicology data is for determining what biomarkers (including both the a toxicant and its metabolites) may be used for biomonitoring, and establishing biological exposure indices.  These are used during exposure assessment and workplace health surveillance activities to identify overexposure, and to test the validity of occupational exposure limits.  These biomarkers are intended to aid in prevention by identifying early adverse affects, unlike diagnostics for clinical medicine that are designed to reveal advanced pathologic states.
In the United States, the Occupational Safety and Health Administration as of 2017 has three regulations that require biomonitoring: after exposure to benzene in an unplanned release, and for employees exposed to cadmium or lead at or above a specified level over a specified amount of time.  In the European Union, biological limit values are health-based, while biological guidance values are statistically derived and indicate background exposures in the general population.  As of 2020 lead is the only substance that has a binding biological limit value in the EU.  Voluntary lists of biological exposure limits or action levels are maintained by the American Conference of Governmental Industrial Hygienists, German Research Foundation, UK Health and Safety Executive, France's ANSES, and the Swiss Accident Insurance Fund.  Biomonitoring for research purposes is performed by the U.S. National Institute for Occupational Safety and Health as part of its Adult Blood Lead Epidemiology and Surveillance program, as well as other occupational health studies.