A version of this story was originally published in the Summer 2012 UW SRP eBulletin.
Parkinsonism, the term for a movement disorder syndrome that includes Parkinson’s Disease, is clinically characterized by slow movement, rest tremors and rigidity. The syndrome is estimated to affect up to 40 percent of the population over sixty years of age. Manganese, an essential element, can cause nervous system damage and contribute to parkinsonism risk as a result of long-term occupational exposure. The Agency for Toxic Substances and Disease Registry, a federal public health agency that works to prevent harmful exposures and diseases related to toxic substances in hazardous waste sites, has said there is clear evidence from studies of humans occupationally-exposed to manganese that inhalation of high levels of manganese can lead to a series of serious and ultimately disabling neurological effects. Welders are a group that routinely experience high-level exposures to manganese. In two related projects in the UW Superfund Research Program, Drs. Harvey Checkoway and Jing Zhang are studying parkinsonism risks in relation to manganese exposures from an epidemiological and basic science perspective in a large group of professional welders. The results thus far from the epidemiological component show an excessive frequency of clinically-determined parkinsonism among the welders. Dr. Zhang’s lab has evaluated several proteins, typically related to Parkinson's Disease, in blood samples of welders, revealing unique alterations.
Ongoing and future research on these projects will determine whether there is a quantitative relationship between manganese and other welding fume metals with parkinsonism and whether similar associations are observed between these metals and parkinsonism-related blood proteins. There have been numerous previous studies of welding exposures in relation to parkinsonism, yet none has approached the level of clinical and basic science rigor achieved in the UW-SRP research. Ultimately, this research has very good potential to add important new information to the causes and early detection of parkinsonism that can benefit disease prevention programs. Insofar as metals that are toxic to the nervous system, such as manganese, copper, and lead, are widespread environmental contaminants, this research should have broad public health implications.