Isocyanate Exposures in Autobody Shop Work: The SPRAY Study

Abstract

Isocyanates, known to cause respiratory sensitization and asthma, are widely used in automotive refinishing where exposures to aliphatic polyisocyanates occur by both inhalation and skin contact. The work reported here, the characterization of isocyanate exposure in the autobody industry, was part of an epidemiologic study of workers in 37 autobody shops in Connecticut. This article describes workplaces, tasks, and controls, and outlines the frequency, duration, and intensity of isocyanate exposures. Personal air samples taken outside of respirators had median concentrations of 66.5 μg NCO/m³ for primer, 134.4 μg (NCO)/m³ for sealer, and 358.5 μg NCO/m³ for clearcoat. Forty-eight percent of primer, 66% of sealer, and 92% of clearcoat samples exceeded the United Kingdom Health and Safety Executive guideline for isocyanate, though none exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit for monomer. Nonisocyanate-containing primers and sealers are used in more than half the shops, but nonisocyanate clearcoats are rare. Eighty-two percent of personal samples taken within a spray booth exceeded the U.K. guideline: 81% of those in downdraft spray booths, 74% in semidowndraft booths, and 92% in crossdraft booths. Only 8% of shops reported that spraying is done exclusively in spray booths. All painters wore some type of respirator. In 30% of shops, painters used supplied air respirators; the rest relied on half face organic vapor cartridge respirators with N95 overspray pads. All shops provided some type of gloves, usually latex, not recommended for isocyanate protection. Despite improvements in autobody shop materials, practices, and controls, there are still opportunities for substantial exposures to isocyanates.

Keywords:

• autobody shop
• isocyanate
• occupational exposures
• small industry

ACKNOWLEDGMENTS

We wish to thank all proprietors and workers whose cooperation made the study possible. We are grateful to Frank Walsh for his invaluable assistance and good humor. This study was supported by CDC/NIOSH grant #R01-OH03457.

Notes

^A In only one shop, a small amount of isocyanate-containing hardener was used in the basecoat formulation.

^A As reported by owner.

^B Work history forms collected by interview from individual workers. Employment of <3 months duration not counted.