Objectives Only a small number of studies have reported on the association of parental occupational exposure to benzene and risk of childhood and adolescent leukaemias. We examined associations with acute lymphoblastic leukaemia (ALL) in this population-based study in Denmark.
Methods Benzene was largely banned from Danish workplaces after 1975, thus this case-control study focused on the immediately prior years. Paediatric cancer cases (<age 20) were ascertained from the Danish Cancer Registry among children born 1968–1974, and controls were selected from population records. Paternal occupation within the 3 months preconception and maternal pregnancy occupation were identified from nationwide pension fund records. Blinded, we assigned benzene exposure using a job-exposure matrix that had been developed for the Danish population. Risk for ALL was estimated using conditional logistic regression. In an exploratory analysis, we also examined other cancers with at least five case parents exposed.
Results We identified 217 employed case fathers and 169 employed case mothers, of which 22 (10.1%) and 11 (6.5%), respectively, were exposed to benzene (vs 6.7% and 2.9% of control fathers and mothers). Most exposed parents worked as machine or engine mechanics, or in the shoe industry. Maternal occupational exposure to benzene in pregnancy was related to increased risk of ALL in offspring (adjusted OR=2.28, 95% CI 1.17 to 4.41), while paternal preconceptional benzene exposure was not as strongly associated (adjusted OR=1.40, 95% CI 0.88 to 2.22).
Conclusions Our study supports an increased risk for ALL with parental occupational benzene exposure.
- acute lymphoblastic leukaemia
- germ cell tumour
- acute undifferentiated leukemia
- parental occupational exposure
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Contributors JEH conceived, designed the presented work and drafted the article. JH acquired and linked data. DH and ZAC performed the data analysis. All authors reviewed results, commented on the manuscript and approved of the final version to be published.
Funding This study was supported by grants from the US National Institutes of Health (R21CA175959, R03ES021643). JEH was supported from a grant from Alex’s Lemonade Stand Foundation (grant 17-01882).
Competing interests None declared.
Ethics approval Human subjects approvals for this study were received from the Danish Data Protection Board and the University of California, Los Angeles, California, USA.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.