Leukemia Risk Associated with Benzene Exposure in the Pliofilm Cohort. II. Risk Estimates

Abstract

The detailed work histories of the individual workers composing the Pliofilm cohort represent a unique resource for estimating the dose-response for leukemia that may follow occupational exposure to benzene. In this paper, we report the results of analyzing the updated Pliofilm cohort using the proportional hazards model, a more sophisticated technique that uses more of the available exposure data than the conditional logistic model used by Rinsky et al. The more rigorously defined exposure estimates derived by Paustenbach et al. are consistent with those of Crump and Allen in giving estimates of the slope of the leukemogenic dose-response that are not as steep as the slope resulting from the exposure estimates of Rinsky et al. We consider estimates of 0.3-0.5 additional leukemia deaths per thousand workers with 45 ppm-years of cumulative benzene exposure to be the best estimates currently available of leukemia risk from occupational exposure to benzene. These risks were estimated in the proportional hazards model when the exposure estimates of Crump and Allen or of Paustenbach et al. were used to derive a cumulative concentration-by-time metric.

Dermal exposure assessment in occupational epidemiologic research

“…The algorithm included the application method (tractor-or boom-, backpack-, bike-spraying), the method of mixing and loading (direct tank filling, pouring, or scooping), the method of bulb disinfection (manual or mechanical dipping), the application rate (milligrams per hectare), the bulb acreage (hectares), the number of applications, the number of bulbs disinfected per year (number of containers), and a protection factor for personal protective equipment (range: 0 = no protection to 1 = complete protection) (24). In a study of Pliofilm™ workers, exposure to benzene was calculated on the basis of the concentration of benzene in the cement being used, the number of skin contacts with the cement per day, the surface area of the contacted skin (square centimeters), and the contact time (hours per day) (25)(26)(27). Dermal uptake (milligrams per kilogram per day) was subsequently calculated using these dermal exposure estimates, the dermal absorption rate (milligram per square centimeter per hour), and body weight of the individual (kilograms).…”

Autonomous Growth of Committed Hematopoietic Progenitors From Peripheral Blood of Workers Exposed to Low Levels of Benzene

“…8, 11 We can estimate that our workers will be exposed to less than 50 ppm-years until retirement, which has not been demonstrated to increase the risk of developing acute myeloid leukemia, 12 and it has been estimated that the lifetime risk of acute leukemia with such exposures is not significantly higher than the risk in the general population. 13 Myeloproliferative diseases are uncommon in the general population and in workers exposed to low concentrations of benzene at work. Therefore, a finding of independent progenitor cell colony growth in a worker exposed to benzene should not be used as evidence of an increased risk for disease and not in decisions of fitness for work.…”

Airborne Concentrations of Benzene Due to Diesel Locomotive Exhaust in a Roundhouse

“…Some have suggested that exposure to benzene may be associated with other leukemias, such as chronic myeloid leukemia and multiple myeloma (NIOSH, 1977;Rinsky et al, 1981Rinsky et al, , 1987Snyder, 2000). However, failure to identify additional cases of multiple myeloma in the Pliofilm cohort weakens any previously reported associations between multiple myeloma and benzene exposure (Paxton et al, 1994a(Paxton et al, , 1994bPaxton, 1996;Wong, 1995). No association between leukemogenic effects and low or background concentrations of benzene (less than 0.5 ppm) has been shown (Raabe & Wong, 1996).…”