Childhood cancer and residential proximity to petrol stations: a nationwide registry-based case–control study in Switzerland and an updated meta-analysis

Abstract

Purpose Benzene is a known carcinogen for adult leukemia. Exposure to benzene through parental occupation and the use of household products has been associated with childhood leukemia (CL). Ambient benzene has also been associated with CL and central nervous system (CNS) tumors. We aimed to investigate whether the higher ambient levels of benzene in proximity of petrol stations are associated with a greater risk of childhood cancers, leukemia, and CNS tumors. Methods We identified children diagnosed with cancer at age 0–15 years during 1985–2015 from the Swiss Childhood Cancer Registry and selected 10 age and sex-matched controls per case from national censuses. We calculated the distance from children’s home to the nearest petrol station using precise geocodes. We estimated odds ratios using conditional logistic regression adjusting for ambient levels of NO2, distance to highways, level of urbanization, and presence of a cantonal cancer registry. In addition, we ran a meta-analysis pooling current results for CL with those of previous studies. Results We identified 6129 cases, of which 1880 were leukemias and 1290 CNS tumors. 24 cases lived within 50 m from a petrol station. The adjusted odds ratio of a cancer diagnosis for children thus exposed compared to unexposed children (> 500 m) was 1.29 (0.84–1.98) for all cancers combined, 1.08 (0.46–2.51) for leukemia, and 1.30 (0.51–3.35) for CNS tumors. During 2000–2015, when exposure assessment was more precise, the adjusted odds ratio for any cancer diagnosis was 1.77 (1.05–2.98). The summary relative risk estimate for CL in the meta-analysis including four studies was 2.01 (1.25–3.22). Conclusions Our study provides weak support for an increased risk of childhood cancers among children living close to petrol stations. A meta-analysis including our study suggests an increased risk for CL.

Risk Factors for Childhood Leukemia: Radiation and Beyond

“…Among the recognized risk factors are high and low birth weight (128) and sex, with boys more often affected than girls (129). Pesticide exposure (130,131), air pollution (132)(133)(134), paint (135), paternal tobacco smoking (136,137), and prelabour cesarean delivery (138) have been associated with an increased risk for ALL or AML but to date none of them is regarded as an established risk factor. There are also some factors that have been associated with a reduced risk for leukemia in the child, including maternal supplementation with folic acid or vitamins (139), or breastfeeding (140).…”

Residential proximity to petrol stations and risk of childhood leukemia

“…One study validated questionnaire-based exposure using georeferencing data [ 44 ]. The three remaining studies used georeferencing data for exposure assessment [ 33 , 45 , 46 ], one in particular through evaluation of petrol station density (number of stations per km 2 ). Results of the bias assessment are reported in Supplemental Table S4.…”

“…The ages of the study populations for all in the range 0-14 years, with dates of diagnosis ranging from 1985 to 2019. All studies had a case-control design, including a case-cohort study [33]. Three studies investigated exposure to petrol station using questionnaire [42][43][44], although one study assessed exposure to both petrol station and car repair garage [43].…”

“…An additional case-control study [ 45 ] revealed an exposure-response relation between petrol station density (per square kilometer), as a marker of traffic-related air pollution, and the risk of leukemia in young children. A nationwide case-control study carried out in Switzerland (during 1985–2015) found evidence of an increased risk of childhood cancer (all diagnoses combined) among children living in close vicinity (< 50 m vs. ≥500 m) of petrol stations [ 33 ].…”

“…We assessed the extent to which residential exposure to gasoline service stations was associated with risk of childhood leukemia in Northern Italy, by considering both distance from the stations located within proximity of the residence and gas station activity. We also critically summarized existing epidemiologic evidence on the risk of childhood leukemia following long-term exposure to gasoline service stations, updating a previous meta-analysis on this topic [ 33 ].…”