BACKGROUND: Many auto body shops are transitioning from solvent basecoats to waterborne basecoats. In some jurisdictions, this transition is being prompted by stringent air quality standards, although the transition has been voluntary in King County, Washington. The purpose of this study was to understand how waterborne coatings are used in auto body shops, with the goal of evaluating their safety relative to traditional solvent-based coatings.
METHODS: Eleven painters from ten auto body shops in King County that use waterborne coatings were recruited to participate in this study, which was comprised of: 1) documenting painters’ work practices; 2) measuring painters’ personal breathing zone exposures; 3) evaluating the performance of spray booths; 4) determining the ethylene glycol monobutyl ether (EGBE) content of the waterborne basecoats; 5) documenting waste management practices; and 6) designating the waterborne waste streams according to Washington state’s dangerous waste regulations.
RESULTS: Painter’s work practices were generally equivalent in all shops because the required tasks were similar. Differences were noted in the use of personal protective equipment (PPE) (especially respirators) and the number of basecoat layers required to produce an acceptable finish. We also noted considerable variation in the way painters cleaned their spray guns. Other minor differences reflected the quantity of vehicles that required painting during the workday and the availability of assistants to help with vehicle preparation. Breathing zone concentrations of waterborne basecoat constituents were much lower than their occupational exposure limits.Painting was conducted primarily in prefabricated downdraft spray booths, but the air flow rates typically failed to meet OSHA requirements. We noted higher concentrations of airborne chemicals when painting took place in un-enclosed “prep stations”. EGBE was detected in waterborne basecoats manufactured by PPG, Sherwin-Williams, and BASF, but was undetected in Spies-Hecker and Cromax products. Procedures for disposing of waterborne coating wastes varied between shops. Many shops were disposing of their waterborne paint wastes without adequate characterization.
CONCLUSIONS: Waterborne basecoats appear to be preferable to solvent-based basecoats. Although airborne exposures to the constituents of all the waterborne basecoats evaluated in this study were relatively low, these products are not hazard-free. Consequently, painters should wear appropriate PPE whenever they handle paints and wastes, with a particular emphasis on preventing dermal exposures. Attention should also be paid to performance and maintenance of spray booths, cleaning of paint guns, and management of waste streams.