1. ^aRTI International, Research Triangle Park, North Carolina, USA
2. ^bDepartment of Epidemiology, the University of North Carolina at Chapel Hill, North Carolina, USA
3. ^cNational Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
4. ^dDepartment of Environmental Sciences and Engineering, the University of North Carolina at Chapel Hill, North Carolina, USA

Correspondence: Dr Ellen Kirrane, RTI International, Environmental Health and Epidemiology Program, Survey Research Division, 3040 Cornwallis Road, Research Triangle Park, NC 27709-2194, USA. Tel.: +1 919 990 8403; Fax: +1 919 541 7250; E-mail: ekirrane@rti.org

Received 21 June 2005; Accepted 13 March 2006; Published online 31 May 2006.

Abstract

Commercial fishers are exposed to unburned hydrocarbon vapors and combustion products present in the emissions from their boat engines. The objective of this study was to measure personal exposure to benzene as a marker of fuel exposure, and to predict exposure levels across categories of carbureted two-stroke, four-stroke and diesel engines. A self-monitoring approach, employing passive monitors, was used to obtain measurements of personal exposure to benzene over time. Mixed-effect linear regression models were used to predict exposure levels, identify significant effects and determine restricted maximum likelihood estimates for within- and between-person variance components. Significant fixed effects for engine type and refueling a car or truck were identified. After controlling for refueling, predicted benzene exposure levels to fishers on boats equipped with two-stroke, four-stroke and diesel engines were 58.4, 38.9 and 15.7 g/m³, respectively. The logged within-person variance component was 1.43, larger than the between-person variance component of 1.13, indicating that the total variation may be attributable to monitor placement, environmental conditions and other factors that change over time as well as differences between individual work practices. The health consequences of exposure to marine engine emissions are not known. The predicted levels are well below those at which health effects have been attributed, however.