Abstract—Research into the causes of Parkinson disease (PD) has accelerated recently with the discovery of novel gene
mutations. The majority of PD cases, however, remain idiopathic and in those cases environmental causes should be
considered. Several recent reports have focused on welding and manganese toxicity as potential risk factors for parkinson-
ism and some have even proposed that welding is a risk factor for PD. The controversy has stimulated this review, the
primary aim of which is to critically and objectively examine the evidence or lack of evidence for a relationship among
welding, manganese, parkinsonism, and PD.
NEUROLOGY 2005;64:2021–2028