The U.S. Environmental Protection Agency (EPA) has released action plans to address the potential health risks of methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), and related compounds. Americans may be exposed to these chemicals when they are used in certain applications such as spray foam insulation, sealing concrete or finishing floors. The plans identify a range of actions the agency is considering under the authority of the Toxic Substances Control Act. Spray polyurethane foam (SPF) is a highly-effective and widely used insulation and air sealant material. However, exposures to its key ingredient, isocyanates such as MDI, and other SPF chemicals in vapors, aerosols, and dust during and after installation can cause adverse health effects.
"There has been an increase in recent years in promoting the use of foams and sealants by do-it-yourself energy-conscious homeowners, and many people may now be unknowingly exposed to risks from these chemicals," said Steve Owens, assistant administrator for EPA’s Office of Chemical Safety and Pollution Prevention. "EPA is working to protect the health of the American people and the environment."
Diisocyanates are powerful irritants to the mucous membranes of the eyes and gastrointestinal and respiratory tracts. Direct skin contact can also cause marked inflammation. Isocyanates can also sensitize workers, making them subject to severe asthma attacks if they are exposed again. Death from severe asthma in some sensitized subjects has been reported.
Isocyanates are reactive to water, and are classified as sensitizers. Atomization, and heating over 115F, as well as direct skin contact of liquid or un-reacted solid (hot melt) can cause sensitivity to humans. Repeated exposure or those already sensitive to chemicals can increase sensitivity over repeated contact, potentially resulting in hypersensitivity.
Diisocyanates are used to make polyurethane polymers. Most polyurethane products, such as foam mattresses or bowling balls, are fully reacted or "cured," and are not of concern. 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.
The chemicals have been documented as a cause of work-related asthma. 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. 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.
For further information: http://yosemite.epa.gov/opa/admpress.nsf/0/B6930D85250395C185257871005AC462