Population-based study of amyotrophic lateral sclerosis and occupational lead exposure in Denmark

Abstract

ObjectivesPrevious research has indicated links between lead (Pb) exposure and increased risk of neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). In this study, we evaluated the association between occupational Pb exposures and ALS.MethodsALS cases were ascertained through the Danish National Patient Registry from 1982 to 2013 and age and sex-matched to 100 controls. Using complete employment history since 1964 from the Danish Pension Fund, cumulative Pb exposure was estimated for each subject via a Danish job exposure matrix. Associations were evaluated using conditional logistic regression analyses and stratified by sex.ResultsFor men with >50% probability of exposure, there was an increase in odds of ALS for exposures in the 60th percentile or higher during any time 5 years prior to diagnosis (aOR: 1.35; 95% CI 1.04 to 1.76) and 10 years prior to diagnosis (aOR: 1.33; 95% CI 1.03 to 1.72). No significant associations were observed in women, and there were no linear trends seen for Pb exposures for either sex.ConclusionsOur study indicates an association between consistently higher occupational Pb exposures and ALS. These findings support those of previously reported associations between ALS and specific occupations that commonly experience Pb exposure.

Blood Metal Levels and Amyotrophic Lateral Sclerosis Risk: A Prospective Cohort

“…Previously observed positive associations between lead level and risk of ALS were based on the comparison of (post-disease onset) blood levels, 6,7,16 as well as on assessments of occupational exposure to lead, using registry data. 17 Our data support these observations. The relatively small magnitude of increase in risk observed for lead in our study may reflect the multifactorial nature of ALS, in which lead exposure is one of the potential steps in the multistage etiologic process leading to the disease.…”

Risk factors for amyotrophic lateral sclerosis: A regional United States case‐control study

“…Our historical data on the interval from exposure to diagnosis of ALS demonstrate a greater risk of ALS with earlier lead exposures that stopped 20 to 40+ y prior to diagnosis, compared to exposures stopping more recently (<20 y ago). Consistent with this is a Danish report that occupational lead exposure 10‐y prior to diagnosis increased ALS risk (OR 1.33, 95% CI 1.03‐1.72) 35 . Bone lead levels have been reported to be higher in ALS patients 36,37 .…”

Epidemiology of amyotrophic lateral sclerosis: an update of recent literature

“…Other recent epidemiologic studies focused on occupational exposure, dietary habits, and physical fitness. In three Danish population-based studies using complete employment history, ALS was linked to diesel exhaust [47], lead [17,48], work-related intense physical activity [17], and specific occupations including agriculture, hunting, forestry, fishing, and construction work [17]. Similarly, a multicenter population-based control study found a positive association of diesel exhaust, silica, organic dust, and extremely low-frequency magnetic fields and electric shocks with ALS risk [24,49].…”