Too hot to handle: An unusual exposure of HDI in specialty painters

Background Hexamethylene Diisocyanate (HDI) is a color stable aliphatic iso cyanate that is used in specialty paints as a hardener. Due to the lower va por pressure of its commercial biuret form, if is considered a relatively " safe" isocyanate from an exposure standpoint. This case series reports on a n unusual toxic exposure to HDI. Between November 1993 and May 1994, seven specialty painters and one boiler maker who were working at three different power plants were examined at the Institute of Occupational and Environmen tal Health at West Virginia University. At their respective work sites, HDI was applied to the hot surfaces of boilers that were not shut down, and al lowed sufficient time to cool. Consequently, these workers were exposed to volatile HDI and its thermal decomposition products. Methods All of these workers underwent a complete physical examination spir ometry, and methacholine challenge testing. Results All 8 workers complained of dyspnea, while 4 of the 8 also complain ed of rash. On examination 3 workers were methacholine challenge positive a nd 2 had persistent rash. At follow-up 4 years later; 5 workers still had t o use inhalation medication and one had progressive asthma and dermatitis. All 8 workers, by the time of the follow-lip, had gone through economic and occupational changes. Conclusions This case series reports on an unusual exposure to HDI. It is u nusual in that: 1) There were two simultaneous sentinel cases with two diff erent Material Safety Data Sheets (MSDS) for the same product, 2) Exposure was to volatile HDI and its decomposition products and 3) Hazardous conditi ons of exposure occurred at three different sites. Am. J. Ind. Med. 37:431- 437, 2000. (C) 2000 Wiley-Liss, Inc.