People who spray foam insulation, seal concrete or finish floors may be exposing themselves to methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI), two chemicals the U.S. Environmental Protection Agency (EPA) are considering taking action on under the authority of the Toxic Substances Control Act.

Diisocyanates are used to make polyurethane polymers. According to a statement released by the EPA, most polyurethane products, such as foam mattresses or bowling balls, are fully reacted or "cured," and pose no danger. “Some products, however, such as adhesives, coatings, and spray foam, continue to react while in use, and may contain "uncured" diisocyanates to which people may be exposed. “

Diisocyanates are known to cause severe skin and breathing responses in workers who have been repeatedly exposed to them. The chemicals have been documented as a leading cause of work-related asthma, and in severe cases, fatal reactions have occurred. To protect worker health, the Occupational Safety and Health Administration (OSHA) regulates workplace exposures through permissible exposure limits. In contrast to the availability of exposure data for professionals who work with diisocyanates, there is very limited information available about the use and exposure patterns of consumers who may be exposed to products containing uncured MDI and TDI. The EPA plans to carefully consider the potential risks from consumer exposure to these chemicals.

Actions to address concerns associated with TDI, MDI, and related compounds include issuing rules to call in data on any past allegations of significant adverse effects, obtain unpublished health and safety data from industry sources, require exposure monitoring studies for consumer products, and possibly ban or restrict consumer products containing uncured MDI or TDI. EPA will continue to work with other federal agencies, the polyurethanes industry, and others to ensure improved labeling and provide comprehensive product safety information for polyurethane products containing uncured compounds, especially in consumer products.