A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
An assessment of the possible extent of confounding in epidemiological studies of lung cancer risk among roofers
The U.S. roofing industry employs about 200,000 workers and estimates indicate about 50,000 on-roof workers are exposed to asphalt fumes during approximately 40% of their working hours. Numerous epidemiological studies have been conducted to evaluate cancer outcomes among roofers, including exposure to asphalt/bitumen fume. However, most studies relied on job title as a surrogate for exposure to asphalt or asphalt fumes because individual exposure data were not available. Therefore, it is unclear whether reported results of an increased risk of lung cancer reflect the direct impact of asphalt exposure on employee health, or if findings are due to bias, such as the presence of other risk factors for lung cancer (i.e., 'confounding' exposures) or the use of comparison populations that are inherently different with respect to lung cancer risk. We evaluated the likelihood and extent to which the observed increased risk of lung cancer may be due to confounding (a mixing of effects of multiple exposures) by co-exposure to other potential carcinogens present in roofing or to lifestyle variables. We conducted a review of the epidemiological and industrial hygiene literature of asphalt-exposed workers. The results of the study indicate that much of the observed risk reported in epidemiological studies of cancer among roofers is well within the range of what may have resulted from confounding by reasonable and expected levels of smoking, asbestos or coal tar. This may be particularly true for those studies that did not adjust for these confounders and where the exposure was defined as employment in the roofing industry. In addition to poorly defined asphalt exposure, uncontrolled confounding cannot reliably be ruled out in studies of lung cancer among asphalt-exposed roofers. Therefore, it is not possible to conclude whether roofers are at increased risk of lung cancer due to asphalt exposure.
An assessment of the possible extent of confounding in epidemiological studies of lung cancer risk among roofers
The U.S. roofing industry employs about 200,000 workers and estimates indicate about 50,000 on-roof workers are exposed to asphalt fumes during approximately 40% of their working hours. Numerous epidemiological studies have been conducted to evaluate cancer outcomes among roofers, including exposure to asphalt/bitumen fume. However, most studies relied on job title as a surrogate for exposure to asphalt or asphalt fumes because individual exposure data were not available. Therefore, it is unclear whether reported results of an increased risk of lung cancer reflect the direct impact of asphalt exposure on employee health, or if findings are due to bias, such as the presence of other risk factors for lung cancer (i.e., 'confounding' exposures) or the use of comparison populations that are inherently different with respect to lung cancer risk. We evaluated the likelihood and extent to which the observed increased risk of lung cancer may be due to confounding (a mixing of effects of multiple exposures) by co-exposure to other potential carcinogens present in roofing or to lifestyle variables. We conducted a review of the epidemiological and industrial hygiene literature of asphalt-exposed workers. The results of the study indicate that much of the observed risk reported in epidemiological studies of cancer among roofers is well within the range of what may have resulted from confounding by reasonable and expected levels of smoking, asbestos or coal tar. This may be particularly true for those studies that did not adjust for these confounders and where the exposure was defined as employment in the roofing industry. In addition to poorly defined asphalt exposure, uncontrolled confounding cannot reliably be ruled out in studies of lung cancer among asphalt-exposed roofers. Therefore, it is not possible to conclude whether roofers are at increased risk of lung cancer due to asphalt exposure.
An assessment of the possible extent of confounding in epidemiological studies of lung cancer risk among roofers
Eine Bestimmung des möglichen Ausmaßes der Vermischung von Risikofaktoren in den epidemiologischen Untersuchungen des Lungenkrebsrisikos unter Dachdeckern
Mundt, Diane J. (author) / Wijngaarden, Edwin van (author) / Mundt, Kenneth A. (author)
2007
12 Seiten, 3 Tabellen, 93 Quellen
Conference paper
English
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