Isocyanate

[5] Also, oxalyl chloride can be used to form acyl isocyanates from primary amides, which phosgene typically dehydrates to nitriles instead.

[7] Aryl isocyanates can be synthesized from carbonylation of nitro- and nitrosoarenes; a palladium catalyst is necessary to avoid side-reactions of the nitrene intermediate.

If a diisocyanate is treated with a compound containing two or more hydroxyl groups, such as a diol or a polyol, polymer chains are formed, which are known as polyurethanes.

[22] These limits are set to protect workers from chronic health effects such as occupational asthma, contact dermatitis, or irritation of the respiratory tract.

[24][25] In the U.S., OSHA conducted a National Emphasis Program on isocyanates starting in 2013 to make employers and workers more aware of the health risks.

[37] Even when the right personal protective equipment (PPE) is used, exposures can occur to body areas not completely covered.

[38] Isocyanates can also permeate improper PPE, necessitating frequent changes of both disposable gloves and suits if they become over exposed.

[24][44] If human workers must enter isocyanate-contaminated regions, personal protective equipment (PPE) can reduce their intake.

In general, workers wear eye protection[44] and gloves and coveralls to reduce dermal exposure[45][46][25][47] For some autobody paint and clear-coat spraying applications, a full-face mask is required.

[31][32] The US Occupational Safety and Health Administration (OSHA) requires frequent training to ensure isocyanate hazards are appropriately minimized.

[48] Moreover, OSHA requires standardized isocyanate concentration measurements to avoid violating occupational exposure limits.

In the case of MDI, OSHA expects sampling with glass-fiber filters at standard air flow rates, and then liquid chromatography.

[49] Combined industrial hygiene and medical surveillance can significantly reduce occupational asthma incidence.

[52] Emergency management is a complex process of preparation and should be considered in a setting where a release of bulk chemicals may threaten the well-being of the public.

Below is a sampling, not exhaustive, as less common isocyanates also have specific limits within the United States, and in some regions there are limits on total isocyanate, which recognizes some of the uncertainty regarding the safety of mixtures of chemicals as compared to pure chemical exposures.

[52] 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.

[61] 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.

[62] The American Conference of Governmental Industrial Hygienists (ACGIH) is a non-government organization that publishes guidance known as threshold limit values (TLV)[61] for chemicals based research as constant work exposure level without ill-effect[clarify].

The United Nations, through the World Health Organization (WHO) together with the International Labour Organization (ILO) and United Nations Environment Programme (UNEP), collaborate on the International Programme on Chemical Safety (IPCS) to publish summary documents on chemicals.