The Yale Occupational and Environmental Medicine Program has been studying exposures in autobody shops and the health effects of these exposures to the workers for more than a decade now. At first, we were interested only in isocyanates because they are known to cause respiratory sensitization and asthma, and they are widely used in automotive refinishing - in the paint hardeners. Autobody workers are exposed to these isocyanates, especially hexamethylene diisocyanate (HDI), both by breathing and skin contact.
Survey of Painters and Repairers of Autobodies by Yale (SPRAY)
SPRAY was launched in 1997 to determine how isocyanates found in autobody paints may cause or aggravate asthma and other respiratory symptoms. "Our goal is to study the health risks from exposure to chemicals called isocyanates at autobody shops. We would also like to identify methods to diagnose employees with respiratory problems such as asthma," states the principal investigator, Mark R. Cullen, M.D. SPRAY is funded by the National Institute for Occupational Safety and Health (NIOSH), a division of the US Centers for Disease Control and Prevention (CDC).
What did we do?
We took samples of the air inside 37 shops in Connecticut during all tasks, both inside and outside of respirators, to see how much isocyanate was there; checked shop surfaces and worker skin for isocyanates; and recorded the equipment and policies in each shop regarding protection from these exposures. We also asked the workers questions about their health and work history; measured the lung function of each worker during one week; performed asthma tests for each worker; and took some blood to look for immunological responses to the isocyanates. In all shops, we performed respirator fit testing for the workers as well.
This study found less clinical asthma among autobody workers than we expected (perhaps because workers who developed respiratory illness left the trade) but did show a decline in their respiratory function over the work week. Only 7% of the 262 workers were found to have asthma but painters had a larger drop in lung function over the week [twice as much as technicians and 25 times as much as office workers]. In addition, our immunology testing showed that more painters had antibodies for isocyanate in their blood [31% of painters, 20% of technicians and 6% of office workers].
There is no governmental standard in the US for air levels of the isocyanates found in these paints, but there is one in the UK and very few of our samples exceeded this, even outside the respirators used by the painters. However, 81% of personal samples taken outside respirators in downdraft spray booths, 74% in semi-downdraft booths, and 92% in crossdraft booths, exceeded the British guideline. Only 8% of shops reported that spraying is done exclusively in spray booths. [see results]
Based on these results, we began to look at the other potentially irritating exposures, of which there are many in autobody shops. Paint dust, metal dust, plastic filler dust, and many solvents, such as toluene and xylene, are present in the environment of these shops. We are now measuring these exposures in the air of the original SPRAY shops, and following up the original SPRAY participants with another medical evaluation. This study is continuing.