The Occupational Safety and Health Administration (OSHA) is the regulatory body covering worker safety. OSHA puts forth permissible exposure limit (PEL) 20 ppb for MDI and detailed technical guidance on exposure assessment.
The National Institutes of Health (NIOSH) is the agency responsible for providing the research and recommendations regarding workplace safety, while OSHA is more of an enforcement body. NIOSH is responsible for producing the science that can result in recommended exposure limits (REL), which can be lower than the PEL. OSHA is tasked with enforcement and defending the enforceable limits (PELs). In 1992, when OSHA reduced the PEL for TDI to the NIOSH REL, the PEL reduction was challenged in court, and the reduction was reversed.
The Environmental Protection Agency (EPA) is also involved in the regulation of isocyanates with regard to the environment and also non-worker persons that might be exposed.
The American Conference of Governmental Industrial Hygienists (ACGIH) is a non-government organization that publishes guidance known as threshold limit values (TLV) for . The TLV is not an OSHA-enforceable value, unless the PEL is the same.