Academic journal article Environmental Health Perspectives

Skin Exposure to Isocyanates: Reasons for Concern

Academic journal article Environmental Health Perspectives

Skin Exposure to Isocyanates: Reasons for Concern

Article excerpt

OBJECTIVE: Isocyanates (di- and poly-), important chemicals used worldwide to produce polyurethane products, are a leading cause of occupational asthma. Respiratory exposures have been reduced through improved hygiene controls and the use of less-volatile isocyanates. Yet isocyanate asthma continues to occur, not uncommonly in settings with minimal inhalation exposure but opportunity for skin exposure. In this review we evaluate the potential role of skin exposure in the development of isocyanate asthma.

DATA SOURCES: We reviewed the published animal and human literature on isocyanate skin-exposure methods, workplace skin exposure, skin absorption, and the role of skin exposure in isocyanate sensitization and asthma.

DATA EXTRACTION: We selected relevant articles from computerized searches on Medline, U.S. Environmental Protection Agency, Occupational Safety and Health Administration, National Institute for Occupational Safety and Health, and Google databases using the keywords "isocyanate," "asthma," "skin," "sensitization," and other synonymous terms, and our own extensive collection of isocyanate publications.

DATA SYNTHESIS: Isocyanate production and use continues to increase as the polyurethane industry expands. There is substantial opportunity for isocyanate skin exposure in many work settings, but such exposure is challenging to quantify and continues to be underappreciated. Isocyanate skin exposure can occur at work, even with the use of personal protective equipment, and may also occur with consumer use of certain isocyanate products. In animals, isocyanate skin exposure is an efficient route to induce sensitization, with subsequent inhalation challenge resulting in asthma-like responses. Several lines of evidence support a similar role for human isocyanate skin exposure, namely, that such exposure occurs and can contribute to the development of isocyanate asthma in certain settings, presumably by inducing systemic sensitization.

CONCLUSIONS: Integrated animal and human research is needed to better understand the role of skin exposure in human isocyanate asthma and to improve diagnosis and prevention. In spite of substantial research needs, sufficient evidence already exists to justify greater emphasis on the potential risks of isocyanate skin exposure and the importance of preventing such exposures at work and during consumer use of certain isocyanate products.

KEY WORDS: asthma, dermal exposure, isocyanates, sensitization, skin. Environ Health Perspect 115:328-335 (2007). doi:10.1289/ehp.9557 available via http://dx.doi.org/ [Online 28 November 2006]

**********

Isocyanates, a group of reactive chemicals [with the functional group N = C = O (NCO)] used extensively in the production of numerous polyurethane foams, coatings, and a wide array of consumer products, are a major cause of occupational asthma worldwide. The polyurethane industry has expanded dramatically, along with the number of workers and consumers at risk for exposure. Inhalation has long been considered the primary route of isocyanate exposure, induction of sensitization, and asthma; research, practice, and regulation have focused almost exclusively on understanding and preventing inhalation exposures. Airborne isocyanate exposures have been reduced through improved controls and use of less-volatile isocyanates. Yet isocyanate asthma continues to occur, not uncommonly in work settings where measured isocyanate respiratory exposures are very low or nondetectable, but where there is opportunity for skin exposure.

It has been > 25 years since Karol et al. (1981) demonstrated in guinea pigs that skin contact with isocyanates could lead to sensitization and subsequent asthmatic responses following inhalation exposure. However, knowledge and awareness remain limited regarding the potential for isocyanate skin exposure to contribute to the development of isocyanate asthma. For example, the literature on occupational asthma rarely mentions isocyanate skin exposure as a potential risk factor or target for prevention (Nicholson et al. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.