Development of an occupational air contaminant exposure monitoring and control strategy with application to lead exposure during bridgework

Occupational exposures to air contaminants originating from the performance of tasks can cause severe adverse health effects among the worker population. To anticipate and control these exposures, the mechanisms that produce and prevent pollutant intake among workers need to be understood. Construction workers comprise a population at relatively high risk for lead poisoning because lead and lead-containing compounds are common in certain construction materials, particularly paint. OSHA's most recent lead in construction standard projected that a 4-fold reduction in air-lead concentration during certain work activities (i.e. from a typical value of 200 mug m-3 to 50 mug m-3) would avoid substantial illness among workers. The agency estimated that full compliance with the standard would avert 227,000 acute cases annually and 4000 chronic cases of adverse health effect among 940,000 construction workers. However, the effectiveness of lead health protection programs that address requirements under this standard has remained largely unknown until the research presented in this dissertation. This research characterizes the sources and pathways of airborne lead exposure during bridgework, develops an exploratory model and applies the model toward an analysis of data collected during a large-scale lead health protection intervention. In conjunction with exploring indicators of prevention, the dynamic model for estimating lead intake that is developed as part of this dissertation is calibrated and tested. The model is evaluated with respect to how accurately it predicts lead absorbed during daily intake in a chamber study and during a month of work-related exposure.; The original motivation for this investigation emerged from a NIOSH demonstration project in Connecticut that sought to prevent lead poisoning among bridge workers during an intense effort to rehabilitate the State's bridge infrastructure. Chapter 2 characterizes the structure and execution of lead-related bridgework, the mechanisms of generation, resuspension, transport and removal and the lead concentrations associated with specific tasks. Over 30 different tasks were identified that produce elevated levels of lead in the air (average values range from less than 30 mug m-3 to almost 10000 mug m-3). The variability in each summary estimate is presented in Chapter 2. (Abstract shortened by UMI.)...