Incidence of amyotrophic lateral sclerosis in the province of Novara, Italy, and possible role of environmental pollution

Objective and methods: Based on nationwide death certificates, a cluster of amyotrophic lateral sclerosis (ALS) has been reported in the area of Briga (Novara province, northern Italy), known for its severe environmental contamination. We further investigated this finding, by following up with the collection of recent incidence ALS data in 2002–2012 of Novara province, also to assess the possible long-term effects of environmental pollution in that area. Results: In the whole Novara province we identified 106 ALS cases, of which 35 were from the Briga area. Incidence rates of Novara province were 3.98, 5.14 and 2.97 for the total population, males and females, respectively, compared with the Briga area where they were 4.65, 4.27 and 4.98, respectively. The ratio of observed-to-expected ALS cases in the Briga area, using incidence of the rest of Novara province as a reference, was 1.17 (95% CI 0.81–1.62), with a value of 0.83 (95% CI 0.47–1.37) in males and 1.68 (95% CI 1.03–2.60) in females. Conclusions: Overall, our study did not confirm previous findings of an excess ALS incidence in an area characterised by severe environmental heavy metal pollution, and it suggests the need to interpret with caution clusters identified through mortality data.