Residential exposure to electromagnetic fields and risk of amyotrophic lateral sclerosis in Reggio Emilia, Italy.

Background and Objective: The etiology of amyotrophic lateral sclerosis (ALS) is still unknown. Some epidemiologic studies suggest a relation between occupational exposure to electromagnetic fields (EMF) and increased ASL risk, while very little data is available about the possible role of EMF residential exposure. We investigated this issue in an Italian communitythrough a population-based case-control study.Methods: We calculated the area around the high-voltage power lines in the Reggio Emilia municipality, northern Italy, with estimated magnetic field exposure above 0.1 μT, adding 20 mto the distance from the power lines predicted by the model to account for geocoding inaccuracy. We retrieved new cases of ALS diagnosed among residents in Reggio Emilia municipality between 1995 and 2006, using several data sources such as death certificates, clinical records, hospital discharge registers and drug prescriptions. We randomly selected four controls for each case, matched for year of birth and sex, and we collected information about their residence in the 35 years prior to ALS diagnosis. All this information was included in a Geographical Information System to calculate disease risk associated with EMF exposure.Results: The final study population included 42 cases and 168 controls. ALS risk associated with antecedent residence in the exposed area was 1.8, 1.9, 1.8 and 1.6 at 35, 20, 10 and 0years before diagnosis, respectively. However, all estimates were statistically very unstable due to the low number of exposed subjects (6 controls and 3 cases 20 years before disease onset).Conclusion: Though these results might indicate an excess risk of ALS among residents exposed to EMF from high-voltage power lines, limitations of the study, particularly the small number of exposed subjects, suggest the need to further investigate this issue in larger populations.