Distance to high-voltage power lines and risk of childhood leukemia:An analysis of confounding by and interaction with other potential risk factors

We investigated whether there is an interaction between distance from residence at birth to nearest power line and domestic radon and traffic-related air pollution, respectively, in relation to childhood leukemia risk. Further, we investigated whether adjusting for potential confounders alters the association between distance to nearest power line and childhood leukemia. We included 1024 cases aged <15, diagnosed with leukemia during 1968-1991, from the Danish Cancer Registry and 2048 controls randomly selected from the Danish childhood population and individually matched by gender and year of birth. We used geographical information systems to determine the distance between residence at birth and the nearest 132-400 kV overhead power line. Concentrations of domestic radon and traffic-related air pollution (NOx at the front door) were estimated using validated models. We found a statistically significant interaction between distance to nearest power line and domestic radon regarding risk of childhood leukemia (p = 0.01) when using the median radon level as cut-off point but not when using the 75th percentile (p = 0.90). We found no evidence of an interaction between distance to nearest power line and traffic-related air pollution (p = 0.73). We found almost no change in the estimated association between distance to power line and risk of childhood leukemia when adjusting for socioeconomic status of the municipality, urbanization, maternal age, birth order, domestic radon and traffic-related air pollution. The statistically significant interaction between distance to nearest power line and domestic radon was based on few exposed cases and controls and sensitive to the choice of exposure categorization and might, therefore, be due to chance

Infections in early life and childhood leukaemia risk: a UK case–control study of general practitioner records

We investigated infections in early life (diagnosed in general practice) and subsequent risk of childhood leukaemia in the UK General Practice Research Database (GPRD). All children born at GPRD practices and subsequently diagnosed with leukaemia were identified as cases and were individually matched (on year of birth, sex and practice) to up to 20 controls. The final analysis included 162 leukaemia cases and 2215 matched controls. Conditional logistic regression demonstrated no evidence that children with one or more recorded infection in the first year of life had a reduced risk of leukaemia (OR=1.05, 95%CI 0.69, 1.59; P=0.83) or acute lymphoblastic leukaemia (ALL; OR=1.05, 95%CI 0.64–1.74; P=0.84). Our study provides no support for the Greaves hypothesis, which proposes that reduced or delayed exposure to infections in early life increases the risk of childhood ALL

Proximity to overhead power lines and childhood leukaemia: an international pooled analysis

© 2018, Cancer Research UK. Background: Although studies have consistently found an association between childhood leukaemia risk and magnetic fields, the associations between childhood leukaemia and distance to overhead power lines have been inconsistent. We pooled data from multiple studies to assess the association with distance and evaluate whether it is due to magnetic fields or other factors associated with distance from lines. Methods: We present a pooled analysis combining individual-level data (29,049 cases and 68,231 controls) from 11 record-based studies. Results: There was no material association between childhood leukaemia and distance to nearest overhead power line of any voltage. Among children living < 50 m from 200 + kV power lines, the adjusted odds ratio for childhood leukaemia was 1.33 (95% CI: 0.92–1.93). The odds ratio was higher among children diagnosed before age 5 years. There was no association with calculated magnetic fields. Odds ratios remained unchanged with adjustment for potential confounders. Conclusions: In this first comprehensive pooled analysis of childhood leukaemia and distance to power lines, we found a small and imprecise risk for residences < 50 m of 200 + kV lines that was not explained by high magnetic fields. Reasons for the increased risk, found in this and many other studies, remains to be elucidated

Parental occupation at periconception: findings from the United Kingdom Childhood Cancer Study.

AIMS: To study the risk of childhood cancer in relation to parental occupation and related exposures. METHODS: Self reported occupational data from mothers and fathers of 3838 children with cancer and 7629 control children were analysed. Odds ratios were calculated for 31 "occupational groups" by parent, diagnostic group (leukaemia, acute lymphoblastic leukaemia (ALL), central nervous system tumours, and other cancers) and time of exposure (periconception, birth, and diagnosis). RESULTS: Findings did not support the hypothesis that occupational exposure of fathers to ionising radiation increases the risk of childhood cancer in their offspring. Specific examination of periconceptual chemical exposures showed small but statistically significant increased risks for leukaemia and ALL among children whose fathers were exposed to exhaust fumes, driving, and/or inhaled particulate hydrocarbons. In the remaining analyses, a fourfold increase in the risk of other cancers was observed among the children of fathers working with leather but based on small numbers. Both maternal and paternal exposure to textile dust was related to an increased risk of other cancers. CONCLUSION: Results failed to produce any strong evidence to link parental occupational exposures with an increased risk of childhood cancer. No relation was found for paternal periconceptual exposure to ionising radiation. The consistency of the associations observed between childhood leukaemia and paternal occupational exposure to exhaust fumes, driving, and/or inhaled particulate hydrocarbons at periconception suggest a small risk for vehicle related exhaust. However, other explanations cannot be excluded and further research into the nature of the associations is required