THEGREENGROK    The Chemical Marketplace

Chemical Marketplace: Rage Against the Foam?

by Bill Chameides | May 19th, 2011
posted by Erica Rowell (Editor)

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More than 80,000 chemicals are produced, used, and present in the United States. This is one of their stories.

Plumbers, carpenters and do-it-yourselfers who use spray foams and sealants: beware the diisocyanates.

Last month the Environmental Protection Agency warned that unsuspecting consumers may be getting a lot more than they bargained for when they choose to save money using do-it-yourself spray foams and sealants to insulate walls and patch up unwanted holes and cracks.

What is EPA concerned about? A class of compounds known as diisocyanates — key ingredients in do-it-yourself polyurethane products like spray-foam insulation, sealers, adhesives and finishes.

The Chemical Marketplace
A series that looks at chemicals in everyday consumer products
     Alkylphenols and laundry and such »
     Aluminum and antiperspirants »
     BPAF »
     Dioxin and eggs »
     Flame retardants and pets »
     Fluoride and water »
     Formaldehyde and no-iron shirts
     Insect repellents »
     Nanoparticles and food »
     PAH and seal coats: A no-brainer »
     PBDE and fire retardants »
     PFOA and popcorn »
     Piperonyl butoxide, a pesticde »
     Propoxur and bedbugs »
     Rotenone, a pesticide »
     Spray foams, sealants and cyanates
     TDCPP and the air »
     Triclosan and toothpaste »
     Trihalomethanes (THM) and
showering »

A Little Tech Talk – The Diisocyanate Story

First let’s start with isocyanates. These are organic compounds that contain the following grouping of three atoms — nitrogen (N), carbon (C), and oxygen (O).* Diisocyanates are organic compounds that have two of these three atom groupings.

Diisocyanates are not especially friendly to humans: They cause contact dermatitis, skin and respiratory tract irritations, immune sensitization, as well as asthma, lung damage, and, in severe cases, death. In fact isocyanates are a leading cause of work-related asthma [pdf] with between one and 20 percent of exposed workers developing asthma.

In the workplace diisocyanate exposures are regulated by the government’s Occupational Safety and Health Administration (OSHA), but not so for the consumer market. Why not? Perhaps because it was assumed that consumers had little exposure to diisocyanates. If so, they had it wrong.

Diisocyanates are commonly included in liquids, gels, and sprays used by consumers to produce polyurethane coatings or foams through a curing process that causes the diisocyanates to combine into a solid polymer. Once the curing is complete, all the little nitrogen-carbon-oxygen isocyanate groups [pdf] are locked in the polyurethane, rendering the diisocyanates inert. But before and during the curing process, diisocyanate-containing vapors, aerosols, and dust can be released, and, unless adequate care is taken, may pose a threat to the user and anyone in the immediate vicinity. There is even potential for exposure to diisocyantes after installation if the areas of application are not adequately ventilated.

EPA Takes Steps

Recognizing these exposures can pose serious health risks to consumers, EPA has issued “action plans” for the two most common diisocyanates on the market: toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI). In 2008, 425.2 million pounds of TDI and 192.1 million pounds of pure MDI and 1,418 million pounds of polymeric MDI were sold in the United States. Most of this is used in industrial applications (exposures regulated by OSHA), but there is a growing consumer market for MDI products, and despite industry claims [pdf] to the contrary, it’s not clear [pdf] that TDI is completely absent from the consumer marketplace.

Action plans are a far cry from regulation, so for the time being you can expect to continue to find diisocyanate-containing products on the do-it-yourself shelf. Once its evaluation is complete, EPA may require a range of actions to limit consumer exposures to diisocyanates ranging from better labeling to withdrawing certain uses from the consumer marketplace. But it’s too soon to say whether a total boycott of these products is necessary. For one, the health impacts of the compounds in consumer applications are not well studied and there are data gaps.

So do take extra care when considering the use of spray foams and the like. According to E
PA, some advertising claims for spray foams, for example, do not clearly indicate that these products contain isocyanates or other hazardous chemicals. So user beware. EPA has already launched a website to provide guidance for limiting exposure to MDI (and other hazardous compounds like flame retardants) in spray-foam air sealants and insulations. Finally, before settling on a conventional polyurethane product you may want to search for alternatives — there are some isocyanate-free plastics out there (examples here, here and here.)

The bottom line: With a little precaution you may pluck, from the danger of these nettlesome diisocyanates, a measure of safety.

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End Note

*Isocyanates are distinct from cynates in that the nitrogen atom attaches the nitrogen-carbon-oxygen group to the rest of the compound (N=C=O) whereas for cyanates (which are ordered like so –O–C≡N) the oxygen atom does.

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