Smoking, snuff dipping and the risk of amyotrophic lateral sclerosis--a prospective cohort study.

BACKGROUND

Little is known about the etiology of amyotrophic lateral sclerosis (ALS). The association between cigarette smoking, but not other types of smoking and snuff dipping, and the risk of ALS has been evaluated in several epidemiologic studies. The findings were inconclusive.

METHODS

We studied the association of smoking and snuff dipping with the risk of ALS in the Swedish Construction Workers Cohort, which includes 280,558 male construction workers enrolled between 1978 and 1993 with detailed information on tobacco use. Incident cases of ALS were identified through cross-linkage to the Swedish Inpatient Register. Relative risks and their corresponding 95% confidence intervals (CIs) were estimated using the Cox proportional hazards regression model.

RESULTS

After a mean follow-up duration of 19.6 years, we identified 160 incident cases of ALS through 2004. Compared with non-tobacco use, the relative risk of ALS was 0.8 (95% CI 0.6-1.1) for tobacco smoking and 0.6 (95% CI 0.3-1.5) for snuff dipping, respectively. For tobacco smoking, further stratified analyses of smoking status or types of tobacco smoking did not reveal any excess risks in any strata.

CONCLUSIONS

Our study provides no evidence that smoking or snuff dipping is associated with an increased ALS risk among men.