Parental occupational exposure and risk of childhood central nervous system tumours: A pooled analysis of case-control studies from Germany, France, and the UK

Background Central nervous system (CNS) tumours are the commonest childhood solid malignancy. We assessed the risk of childhood CNS tumours associated with parental occupational exposure to pesticides, polycyclic aromatic hydrocarbons (PAH), diesel motor exhaust (DME), asbestos, crystalline silica, and metals. Methods We pooled three population-based case-control studies from France, Germany and the UK. Cases were children below 15 years of age diagnosed with CNS tumours; controls were matched to cases by gender and age. Socio-demographic and parental occupational information was collected using study-specific standardised interviews, either face-to-face or by telephone. Each study provided occupational data coded according to their national schemes; which were harmonised into ILO's International Standard Classification of Occupations 1968 and 1988. Two general population job-exposure matrices (DOM-JEM, ALOHA+) were used to estimate parental occupational exposures. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using logistic regression. Results The study included 1,361 children with CNS tumours and 5,500 controls. ORs for paternal exposure (yes/no) around conception were as follows: PAH 1.22 (95% CI: 0.98-1.52); metals 1.18 (95% CI: 0.96-1.46); and asbestos 1.12 (95% CI: 0.95-1.32). Asbestos was the only potentially hazardous exposure were the point estimate increased at higher levels; OR 1.42 (95% CI: 0.87-2.32). Paternal exposure to pesticides, DME and silica showed no increased risk. The prevalence of maternal occupational exposures to pesticides, PAH, DME, asbestos, silica, and metals was low; and no increased ORs were observed either around the time of conception or during pregnancy. Conclusion Our large pooled study provided little evidence of an association between paternal occupational exposure to PAH, metals, and asbestos around conception and CNS tumour risk in the offspring. Previous studies have reported inconsistent results for PAH, while no studies have reported significant associations for asbestos and metals.