Childhood cancer and residential exposure to highways: a nationwide cohort study
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Children living near highways are exposed to higher concentrations of traffic-related carcinogenic pollutants. Several studies reported an increased risk of childhood cancer associated with traffic exposure, but the published evidence is inconclusive. We investigated whether cancer risk is associated with proximity of residence to highways in a nation-wide cohort study including all children aged <16 years from Swiss national censuses in 1990 and 2000. Cancer incidence was investigated in time to event analyses (1990–2008) using Cox proportional hazards models and incidence density analyses (1985–2008) using Poisson regression. Adjustments were made for socio-economic factors, ionising background radiation and electromagnetic fields. In time to event analysis based on 532 cases the adjusted hazard ratio for leukaemia comparing children living <100 m from a highway with unexposed children (≥500 m) was 1.43 (95 % CI 0.79, 2.61). Results were similar in incidence density analysis including 1367 leukaemia cases (incidence rate ratio (IRR) 1.57; 95 % CI 1.09, 2.25). Associations were similar for acute lymphoblastic leukaemia (IRR 1.64; 95 % CI 1.10, 2.43) and stronger for leukaemia in children aged <5 years (IRR 1.92; 95 % CI 1.22, 3.04). Little evidence of association was found for other tumours. Our study suggests that young children living close to highways are at increased risk of developing leukaemia.
KeywordsLeukaemia Lymphoma Traffic exhaust Air pollution Tumours of the central nervous system Vehicle emissions
The authors thank Dr. Christian Kreis for his assistance in calculating distance to highways and creating the map. This work was supported by the Swiss Federal Office of Public Health (Grants 08.001616, 10.002946, 12.008357), Swiss Cancer League (Grant 02224-03-2008), and Swiss Cancer Research (Grants 3049-08-2012, 3515-08-2014). BD Spycher was supported by a Swiss National Science Foundation fellowship (PZ00P3_147987). The work of the Swiss Childhood Cancer Registry is supported by the Swiss Paediatric Oncology Group (www.spog.ch), Schweizerische Konferenz der kantonalen Gesundheitsdirektorinnen und –direktoren (www.gdk-cds.ch), Swiss Cancer Research (www.krebsforschung.ch), Kinderkrebshilfe Schweiz (www.kinderkrebshilfe.ch), Ernst-Göhner Stiftung, Stiftung Domarena and National Institute of Cancer Epidemiology and Registration (www.nicer.ch).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Approval of the study was granted through the general cancer registry permission of the Swiss Childhood Cancer Registry by the ethics committee of the canton of Bern.
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