Exposure to benzene in a pooled analysis of petroleum industry case-control studies
Author(s)
Glass, DC
Schnatter, AR
Tang, G
Armstrong, TW
Rushton, L
Type
Journal Article
Abstract
Cases of lymphohematopoietic cancer from three petroleum industry cohorts, matched to controls from the respective cohort, were pooled into single study. Average benzene exposure was quantitatively estimated in ppm for each job based on measured data from the relevant country, adjusted for the specific time period, site and job exposure characteristics and the certainty of the exposure estimate scored. The probability of dermal exposure and of peak exposure was also assessed. Before risk was examined, an exposure estimate comparison and rationalisation exercise was performed across the studies to ensure accuracy and consistency of approach. This article evaluates the final exposure estimates and their use in the risk assessments.
Overall benzene exposure estimates were low: 90% of participants accumulated less than 20 ppm-years. Mean cumulative exposure was estimated as 5.15 ppm-years, mean duration was 22 years, and mean exposure intensity was 0.2 ppm. 46% of participants were allocated a peak exposure (>3 ppm at least weekly). 40% of participants had a high probability of dermal exposure (based on the relative probability of at least weekly exposure).
There were differences in mean intensity of exposure, probability of peak, and/or dermal exposure associated with job category, job site, and decade of exposure. Terminal Operators handling benzene-containing products were the most highly exposed group, followed by Tanker Drivers carrying gasoline. Exposures were higher around 1940–1950 and lower in more recent decades.
Overall confidence in the exposure estimates was highest for recently held jobs and for white-collar jobs. We used sensitivity analyses, which included and excluded case-sets on the basis of exposure certainty scores, to inform the risk assessment.
The above analyses demonstrated that the different patterns of exposure across the three studies are largely attributable to differences in jobs, site types, and time frames rather than study. This provides reassurance that the previous rationalisation of exposures achieved inter-study consistency and that the data could be confidently pooled.
Overall benzene exposure estimates were low: 90% of participants accumulated less than 20 ppm-years. Mean cumulative exposure was estimated as 5.15 ppm-years, mean duration was 22 years, and mean exposure intensity was 0.2 ppm. 46% of participants were allocated a peak exposure (>3 ppm at least weekly). 40% of participants had a high probability of dermal exposure (based on the relative probability of at least weekly exposure).
There were differences in mean intensity of exposure, probability of peak, and/or dermal exposure associated with job category, job site, and decade of exposure. Terminal Operators handling benzene-containing products were the most highly exposed group, followed by Tanker Drivers carrying gasoline. Exposures were higher around 1940–1950 and lower in more recent decades.
Overall confidence in the exposure estimates was highest for recently held jobs and for white-collar jobs. We used sensitivity analyses, which included and excluded case-sets on the basis of exposure certainty scores, to inform the risk assessment.
The above analyses demonstrated that the different patterns of exposure across the three studies are largely attributable to differences in jobs, site types, and time frames rather than study. This provides reassurance that the previous rationalisation of exposures achieved inter-study consistency and that the data could be confidently pooled.
Date Issued
2017-06-26
Date Acceptance
2017-06-01
Citation
Journal of Occupational and Environmental Hygiene, 2017, 14 (11), pp.863-872
ISSN
1545-9624
Publisher
Taylor & Francis
Start Page
863
End Page
872
Journal / Book Title
Journal of Occupational and Environmental Hygiene
Volume
14
Issue
11
Copyright Statement
© 2017 JOEH, LLC. This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Occupational and Environmental Hygiene on 26/06/2017, available online: http://www.tandfonline.com/10.1080/15459624.2017.1339162.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000423260200005&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Life Sciences & Biomedicine
Environmental Sciences
Public, Environmental & Occupational Health
Environmental Sciences & Ecology
Benzene
cohort
exposure assessment
LH cancer
nested case-control study
pooled analysis
DISTRIBUTION WORKERS
PLIOFILM COHORT
UNITED-KINGDOM
LEUKEMIA
RISK
CHINA
EPIDEMIOLOGY
Publication Status
Published