Lead, cadmium and mercury in cerebrospinal fluid and risk of amyotrophic lateral sclerosis: A case-control study

Exposure to neurotoxic chemicals such as pesticides, selenium, and heavy metals have been suggested toplay a role in the etiology of amyotrophic lateral sclerosis (ALS). We assessed exposure to lead, cadmium,and mercury in 38 ALS patients (16 men and 22 females) and 38 hospital-admitted controls by using theircerebrospinal fluid (CSF) content as biomarker. We determined CSF heavy metal levels with inductivelycoupled plasma sector field mass spectrometry, according to a methodology specifically developed forthis biological matrix. ALS patients had higher median values for Pb (155 vs. 132 ng/L) but lower levelsfor Cd (36 vs. 72 ng/L) and Hg (196 vs. 217 ng/L). In the highest tertile of exposure, ALS odds ratio was1.39 (95% CI 0.48–4.25) for Pb, 0.29 (0.08–1.04) for Cd and 3.03 (0.52–17.55) for Hg; however, no dose-response relation emerged. Results were substantially confirmed after conducting various sensitivityanalyses, and after stratification for age and sex. Though interpretation of these results is limited by thestatistical imprecision of the estimates, and by the possibility that CSF heavy metal content may notreflect long-term antecedent exposure, they do not lend support to a role of the heavy metals cadmium,lead and mercury in ALS etiology.