A retrospective mortality study among Canadian petroleum marketing and distribution workers.

Abstract

We conducted a retrospective mortality study among 6672 petroleum marketing and distribution workers from 226 locations throughout Canada. These employees worked for at least 1 year in the marketing distribution segment from 1964 through 1983 or were annuitants as of 1964. Industrial hygienists assigned hydrocarbon (HC) exposure frequency scores for several jobs, departments, and job functions. We computed standardized mortality ratios for the total cohort, HC exposure frequency groups, and tank truck drivers, and we also used Poisson regression techniques to model mortality for selected causes of death according to HC exposure frequency. Results indicate overall mortality below that of the general Canadian population for all marketing distribution workers [Standardized mortality ratio (SMR) = 0.88]. Mortality from aortic aneurysms was significantly elevated in all marketing/distribution workers (SMR = 1.79) but was due to raised mortality in nonexposed workers (SMR = 2.80). Tank truck drivers showed significantly elevated mortality due to leukemia (SMR = 3.35) based on five deaths. The leukemia findings were not evident in the larger group of marketing distribution workers classified as exposed to hydrocarbons (SMR = 1.01). No other cause ofdeath was elevated in truck drivers. The leukemia findings are suggestive of a possible influence due to exposure to HCs in tank truck drivers, although other explanations cannot be ruled out. Other findings of elevated mortality in the marketing distribution group are generally not statistically significant. These included moderately increased mortality due to multiple myeloma, malignant melanoma, and kidney cancer. Small numbers of observed and expected deaths limit concise interpretations for these diseases.

State of the science on the carcinogenicity of gasoline with particular reference to cohort mortality study results.

“…In light of prior evidence of an association between benzene and MM, the increased risk of MM observed in the Schnatter et al study (12) of gasoline-exposed workers is meaningful. A few other studies that presented data separately for MM also suggest elevated risks for MM in relation to employment in refineries (10,(15)(16)(17).…”

“…As the data now stand, one study demonstrates an association between total hydrocarbon exposure from gasoline and kidney cancer in humans (12), and the results were internally consistent. Other studies do not show such an association.…”

“…Of the studies presented at the gasoline symposium, only the Schnatter et al study (12) provides some evidence of an association between gasoline exposure and kidney cancer. The data of this study were internally consistent in that every measure of increasing exposure showed an increasing risk of death from kidney cancer.…”

“…The data of this study were internally consistent in that every measure of increasing exposure showed an increasing risk of death from kidney cancer. For example, the standardized mortality ratio (SMR) for kidney cancer was 135 for the total cohort and 158 for those employees characterized as experiencing "total hydrocarbon" exposure (12 Thus, adjustment for cigarette smoking in the Rushton study (13), as well as in all studies of gasoline-exposed workers, needs to be considered in the analyses. In the absence of this adjustment, it is difficult to evaluate the findings with regard to kidney cancer.…”

“…In the Schnatter et al study (12), multiple myeloma (MM) showed an increase in risk by every measure of increasing exposure. The overall SMR in the study was 183, but those who were characterized as occupationally exposed to hydrocarbons had an SMR of 199.…”