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Consumer Safety and Diisocyanates

Erin Dickison

The business of chemistry touches more than 96 percent of the products that we all use every day and accounts for thousands of new products and innovations each year. For example, the products of diisocyanates (DII) chemistry—from impact-absorbing vehicle parts, to bike helmets, to insulation used in refrigerators to preserve food—contribute to the safety of modern conveniences. The U.S. Environmental Protection Agency (EPA) states that “[c]ompletely cured products are fully reacted and therefore are considered to be inert and non-toxic.”

The chemical industry makes the safety and responsible use of its products a priority. While certain parts of America’s chemical management system require modernization, a robust system of laws and industry initiatives oversees the development and use of chemical products, enhances scientific understanding and makes safety information available to the public.

Policies to Promote Innovation and Safety

Americans must feel confident that the federal regulatory system is keeping pace with the applications of chemistry, including the use of diisocyanates. Our nation’s primary chemicals management law must keep pace with scientific advancements while the agencies work to determine that chemical products are safe for their intended use—while also encouraging innovation and protecting American jobs. Learn more about policies that can help American chemistry continue creating jobs and enhancing safety.

How are consumers protected from potential exposures to diisocyanates?

The vast majority of diisocyanates manufactured are for industrial use. Aromatic diisocyanates are known to cause respiratory sensitization at airborne concentrations above the allowable workplace limits; however, exposure to such airborne concentrations is highly unlikely during the use of consumer products.

Consumer products containing uncured aromatic diisocyanates are very limited (e.g., certain adhesives) and are accompanied by product safety information such as warning labels, the characteristics of the chemicals, their approximate cure time, and how to properly protect yourself while handling the product. Thus, overall, consumer exposures to unreacted diisocyanates are expected to be of very low magnitude and frequency.

How does “curing” take place during formation of a polyurethane product?

This can be explained by looking at how diisocyanates are among the building blocks used to make polyurethanes (PU) products. Curing refers to the reaction that occurs between the two primary chemicals used to form a PU product. These primary chemicals are commonly referred to as a diisocyanate (A-side material) and a polyol (B-side material). The A-side material, or diisocyanate, is highly reactive and curing begins immediately upon mixing with the B-side material. The cure time varies depending on the type of polyurethane product being produced, the ingredient formulations and other factors in the manufacturing process.

Many PU products are completely cured and therefore considered “inert” before they are sold, such as mattresses, pillows, furniture cushions, car seating, refrigerator insulation, footwear, ski bindings or inline skates. This means that the original reactive ingredients, the diisocyanates and the polyols, are no longer present in their original form in the fully cured polyurethane product. As a result of the reaction, they were transformed during production into the finished polyurethane product.

For more answers to questions about diisocyanates, visit the Fast Facts and Frequently Asked Questions section.


A newly published study developed and validated an analytical method for quantification of migration of 4,4’-methylenediphenyl diioscyanate (MDI), 2,6-toluene diisocyanate (2,6-TDI) and 2,4 toluene diisocyanate (2,4-TDI) from a polyurethane flexible foam to artificial sweat. The study concluded that even testing formulations anticipated to have the highest potential residual TDI or MDI showed that free diisocyanates were not detected.

The peer-reviewed study titled “Development of a method for quantification of toluene diisocyanate and methylenediphenyl diisocyanate migration from polyurethane foam sample surface to artificial sweat by HPLC-UV-MS” is available online as an open-access article in the Journal of Chromatography B.

This cutting edge research meets the recommendations of the EPA test protocol for evaluating potential dermal exposure from home furniture. Following the EPA protocol, six synthetic sweat solutions were prepared and used in evaluation of isocyanate recovery performance. The migration tests were conducted using five foam types that were supplied by PU foam manufacturers to represent the types most commonly found in consumer products, and with formulations anticipated to have the highest potential residual TDI or MDI.

According to the study authors, “the method of quantification of diisocyanate migration studied in this project can confirm or determine at what point the diisocyanates are no longer available to migrate to a sweat solution. Therefore, this can be a useful tool in the estimation of the potential risk for dermal exposure.” The authors conclude that “the results of this study suggest that unreacted diisocyanates (MDI, TDI) would not be expected to be present on the surface of, or migrate to skin in contact with, consumer foam products such as those tested here.”

The full article is available in the Journal of Chromatography B.

Helpful Resources for Consumers

Aromatic diisocyanates—primarily MDI and TDI—are used by various industries as building blocks primarily to make polyurethane products, such as rigid and flexible foams, coatings, adhesives, sealants and elastomers. Many of the products that we rely upon every day are safer, tougher and more comfortable through the use of polyurethanes made with diisocyanates (DII) chemistry. Extensive safety precautions are undertaken by the DII and polyurethane industries to address the health and safety of users of DII and to comply with all government regulations.

DII in Spray Polyurethane Foam

For health and safety information about DII use in spray polyurethane foam, visit the Homeowner or Do-it-yourself (DIY) sections of www.spraypolyurethane.org. General information about the use of spray polyurethane foam can be found at www.whysprayfoam.org.