Abstract
Purpose
Published case–control studies of risks of leukaemia following low exposures to benzene in the distribution of petroleum (gasoline) have not all identified the same level of risk, but the studies have had differences in cohort inclusion, case determination and availability of occupational and lifestyle data. We reviewed the quality and comparability of the data from three (of four) studies.
Methods
Through site visits, discussions with the investigators and reading study reports, we reviewed and audited the methods used for selecting cases and controls, for estimating individual exposures and for analysing and interpreting the data. Case–control comparisons of exposures were examined using customised graphs.
Results
We found that
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there were no issues of subject selection, methods or general data quality that were likely to have distorted their internal comparisons;
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we could not check in detail whether the metric for exposure assessments was the same across the studies;
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the exposure assessments for the Australian study required the least backward estimation, and the Canadian, which also had fewest cases, the most;
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evidence of an increased risk at higher exposures in Australia was convincing.
Conclusions
The findings are consistent with some effect of benzene at higher lifetime exposures. A proposed pooled analysis should improve quantification of any exposure–response relationship.
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References
Armstrong TW, Pearlman ED, Schnatter AR et al (1996) Retrospective benzene and total hydrocarbon exposure assessment for a petroleum marketing and distribution worker epidemiology study. Am Ind Hyg Assoc J 57:333–343
Glass DC, Gray CN, Jolley DJ et al (2003) Leukemia risk associated with low-level benzene exposure. Epidemiology 14:569–577
Glass DC, Gray CN, Jolley DJ et al (2004) Benzene exposure and leukemia (Authors’ Response to Letters). Epidemiology 15:510–511
Goldsmith B (2004) Benzene exposure and leukemia (Letter to the Editor). Epidemiology 15:509–510
Greenland S, Schwartzbaum JA, Finkle WD (2000) Problems due to small samples and sparse data in conditional logistic regression analysis. Am J Epidem 151(5):531–539
Hastie TJ, Tibshirani RJ (1990) Generalized additive models. Chapman & Hall, London
IARC (International Agency for Research on Cancer) (2004) IARC monographs on the evaluation of carcinogenic risks to humans, vol 82. IARC, Lyon
Institute of Petroleum (2003) Leukaemia risks in relation to benzene exposure. Report of a meeting held on 22nd October 2002, London: Institute of Petroleum
Miller BG, Fransman W, Heederik D et al. (2005) A review of the data quality and comparability of case–control studies of low-level exposure to benzene in the petroleum industry. Edinburgh: Institute of Occupational Medicine. (IOM Research Report TM/05/04). http://www.iom-world.org/pubs/IOM_TM0504.pdf
Rinsky RA, Smith AB, Hornung R et al (1987) Benzene and leukaemia. An epidemiologic risk assessment. N Engl J Med 316:1044–1050
Rushton L, Romaniuk H (1997) A case–control study to investigate the risk of leukaemia associated with exposure to benzene in petroleum marketing and distribution workers in the United Kingdom. Occup Environ Med 54:152–166
Schnatter AR (2004) Benzene exposure and leukemia (Letter to the Editor). Epidemiology 15:509
Schnatter AR, Armstrong TW, Nicolich MJ et al (1996) Lymphohaematopoietic malignancies and quantitative estimates of exposure to benzene in Canadian petroleum distribution workers. Occup Environ Med 53:773–781
Wong O, Trent L, Harris F (1999) Nested case–control study of leukaemia, multiple myeloma, and kidney cancer in a cohort of petroleum workers exposed to gasoline. Occup Environ Med 56:217–221
Acknowledgments
We are indebted to the principal investigators of the original studies, who gave help, co-operation and encouragement without which this review would have been impossible. Mark Nicolich of Exxon Mobil BSI spotted a mistake in an earlier version of Fig. 1, corrected in the current improved version. We thank CONCAWE for funding the work: the review benefited from advice from a Scientific Steering Committee appointed by them. We thank also our colleagues and three referees, all of whose comments improved this paper.
Conflict of interest statement
The review project was funded by the petroleum industry association CONCAWE. The authors retained full and independent editorial control over all reporting.
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Miller, B.G., Fransman, W., Heederik, D. et al. A review of the data quality and comparability of case–control studies of low-level exposure to benzene in the petroleum industry. Int Arch Occup Environ Health 83, 69–76 (2010). https://doi.org/10.1007/s00420-009-0463-0
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DOI: https://doi.org/10.1007/s00420-009-0463-0