Auteurs

Baldi I, Coureau G, Jaffré A, Gruber A, Ducamp S, Provost D, Lebailly P, Vital A, Loiseau H, Salamon R. Occupational and residential exposure to electromagnetic fields and risk of brain tumours in adults: A case-control study in gironde, france. Int J Cancer. Nov 12, 2010. Ahead of print.

Introduction
The incidence of brain tumors has increased in the last decades in many countries. This increase cannot be fully explained by improved detection due to the development of imaging techniques. Therefore, the role of environmental factors has been hypothesized. One of these hypothetical environmental causes is exposure to electromagnetic fields (EMF). Extremely low frequency fields (ELF), such as those from power lines and electrical appliances, and radiofrequency (RF) electromagnetic fields (EMFs) are considered separately because their biological effects on cells are produced by different mechanisms. Epidemiological research on possible associations between exposure to ELF or RF EMFs and brain tumor risks have produced controversial results.

Objective
The objective of the study was to investigate “the putative association between residential and occupational electromagnetic fields and the risk of brain tumors in a French population-based case-control study”.

Methods
The case-control study included 221 patients aged 16 years and older diagnosed with central nervous system tumors between May 1, 1999 and April 30, 2001 and living in Gironde at the time of the diagnosis. The tumors included 105 gliomas, 67 meningiomas, 33 acoustic neurinomas, 7 brain lymphomas and 9 tumors of other histological types. Controls were randomly selected from the local electoral rolls. Two controls were individually matched to each case for age, sex and department of residence (442 controls in total). Data on occupational and residential histories for assessment of occupational and residential exposures to EMFs, on socio-demographic, environmental and lifestyle factors were obtained from the study subjects using interviewer-administered questionnaires. Occupational exposure to EMFs was assessed by two industrial hygienists. Residential exposure to EMFs was assessed on the basis of distances between high-frequency power lines and place of residence using a Geographical Information System (GIS). Education (as a proxy for socio-economic status), exposures to some chemicals, pesticides and smoking were taken into account as potential confounders.

Results
When all brain tumors were considered together, no significant increase in risk was observed for occupational exposures to ELF, RF, EMFs in total, or for residence proximity to power lines: Odd Ratios (ORs) ranged between 1.50 and 1.59 and their 95% confidence intervals (CI) included 1.0. The brain tumor risk for mobile phone users was non-significantly lower than for non-users: OR=0.82 (95% CI 0.53-1.26). When brain tumors were analyzed by histological type, a significant increase in risk of meningioma was seen for occupational exposure to ELFs: OR=3.02 (95% CI 1.10-8.25). The risk of meningioma was also increased (though non-significantly) for those living at a distance ≤100 m from power lines: OR=2.99 (95% CI 0.86-10.40). Neither occupational exposure to RF nor mobile phone use was associated with significantly increased risk of brain tumors of any histological type. The OR for mobile phone use was below 1.0 (non-significantly) for all types of tumors. The authors point out that the frequency of occupational RF exposure and mobile phone use was low in their population.

Interpretation and Conclusion
The authors have concluded that, although based on a limited number of exposed subjects, their results suggest an association between exposure to ELF and the risk of meningioma.



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