Determining the Frequency of Asbestos Use in Automotive Brakes from a Fleet of On-Road California Vehicles Joseph De Vita, † Stephen Wall, ‡ Jeff Wagner, ‡ Zhong-Min Wang, ‡ and Leela E. Rao †, * † California Air Resources Board, Mobile Source Control Division, El Monte, California 91731, United States ‡ California Department of Public Health, Environmental Health Laboratory, Richmond, California 94804, United States ABSTRACT: Asbestos is a known human carcinogen, and recent regulation in California limits asbestiform fibers in brakes to trace levels beginning in 2014, although there is no corresponding federal requirement. In order to gauge the current prevalence of asbestos use in automotive brake applications, the California Air Resources Board tested brake linings from 137 light- and medium-duty vehicles and 54 heavy-duty vehicles. Only about 3% of the light- and medium- duty vehicle brake linings contained chrysotile asbestos. All of those brake linings were drum-type shoes, which are generally being phased out. No asbestos was found in low mileage vehicles presumed to have their original stock linings from the vehicle manufacturer. Additionally, no asbestos was found in the heavy-duty vehicle brake shoe linings sampled. Given the small percentage of vehicle brake linings with asbestos observed, it appears that the prior federal ban that was subsequently overturned, in combination with a threat of litigation, has reduced asbestos use in brake linings. However, our study was limited in scope and without a national ban, the current and future prevalence of asbestos in brakes is uncertain, suggesting the need for continued monitoring of materials released as toxic air contaminants in normal braking operations. ■ INTRODUCTION Asbestos has been used in many products, including automotive brake linings, cements, millboard, roofing materials, floorings, heat-resistant gaskets, and electrical wiring insulation. 1 For decades, asbestos was the primary material in automotive brake linings due to its thermal stability, low wear rate, low cost, and other useful characteristics. 2 It is estimated that in 2003, 10% of the estimated world sales of chrysotile asbestos was used for brake linings and clutch facings. 3 Chrysotile asbestos was eventually shown to be a human carcinogen and has become the source of much debate and an aggressive litigation industry over the past few decades. Central to the litigation are risks to auto mechanics from handling brake linings containing asbestos, as identified by Castleman et al. 4 and reviewed subsequently by Lemen 5 and Welch. 6 However, asbestos particles are also released into the general environment as a result of routine driving and braking, with airborne concentrations of asbestos close to major highways and roadways up to 3-6 times higher than at locations away from roadways. 7,8 As of 2011, 55 countries, including all member states of the European Union, have banned the use of all forms of asbestos in manufactured products. 9 In 1989, the United States Environmental Protection Agency (USEPA) issued a rule that would have phased out the manufacture, import, and processing of original equipment manufacturer (OEM) asbestos-containing automotive brakes by 1996, 10 but that rule was subsequently overturned in 1991 by the fifth Circuit Court of Appeals. 11 In reaction to the impending U.S. asbestos ban, rising concern in other industrialized countries about asbestos health effects, and ongoing litigation, manufacturers of brake linings began searching for asbestos alternatives. A 1998 report indicated 25% of new vehicles built in the U.S. with OEM drum brakes contained asbestos, 12 but by 2004 a USEPA survey of the nine major OEMs found that none of the major manufacturers sold asbestos brakes in new vehicles or as replacement parts in the U.S. 13 Instead, OEMs were opting to use alternative formulations such as metallic, semimetallic, synthetic, and ceramic fibers. However, no legal impediment to using asbestos exists, and a 2007 Occupational Safety and Health Administration (OSHA) survey found that some vehicles of two OEMs were still equipped with asbestos- containing friction products. 14 Furthermore, aftermarket brake linings containing asbestos are still available as demonstrated by Senator Patty Murray (D-WA), who brought an asbestos brake lining purchased by her staffer to a 2007 U.S. Senate Subcommittee hearing in an effort to dispel the myth that asbestos products are no longer available in the U.S. 15 Current litigation regarding asbestos-related cancer may lead to further reductions in asbestos use, and even greater nationwide reductions may occur due to a California ban on asbestos in friction materials that goes into effect in 2014. 16 Received: August 1, 2011 Revised: December 14, 2011 Accepted: December 14, 2011 Published: December 14, 2011 Article pubs.acs.org/est © 2011 American Chemical Society 1344 dx.doi.org/10.1021/es202667d | Environ. Sci. Technol. 2012, 46, 1344-1351