Neurotoxic Effects of Cumulative Exposures to Maganese and Lead: A Novel Study on Welders

Faculty Researcher: Huiling Nie,  PhD, Assistant Professor, School of Health Sciences, Purdue University

Millions of workers, including over 500,000 welders employed in the United States, have been exposed to excessive metals. Human and animal studies have strongly linked metal exposure to neurophysiological disorders and diseases. Manganese and lead are the two most significant metal neuro-toxicants among workers. Animal studies have demonstrated the synergistic neurotoxic effect of combined exposure to manganese and lead, however, there is no such study in humans. The central hypothesis to be tested in this proposal is that combined exposure to manganese and lead has synergistic neurotoxic effect in humans. We will use the cumulative manganese exposure index reconstructed from history exposure record to assess manganese exposure, and use an advanced bone lead quantification technology to assess lead exposure. Twenty five welders and 25 matching controls who are not occupationally exposed to metals will be recruited from a local company. Their manganese exposure will be reconstructed; their bone lead concentrations will be quantified; and neurophysiological tests will be performed to assess these subjects’ cognitive and motor function. The synergistic neurotoxic effect of combined manganese and lead exposure will be assessed with a chemical mixture model. At the completion of this project, we expect to obtain some preliminary data on the neurotoxic effects of combined exposure to manganese and lead. This pilot project will generate preliminary data which will be used to apply for a larger grant on individual exposure assessment of metals and health effects of occupational exposure to metal mixtures. The understanding of neurotoxic effects of combined exposure to manganese and lead is critical to millions of workers who have been exposed to these metals for two main reasons. First, neurophysiological disorder is one of the main health issues for these workers; second, neurological impairment reduces the workers’ productivity and is a major cause for work related injuries.

Publications resulting from this project:
Liu Y, Byrne P, Wang H, Koltick D, Zheng W, Nie LH. A compact DD neutron generator-based NAA system to quantify manganese (Mn) in bone in vivo. Physiological Measurement. 2014;35(9):1899-1911. doi: 10.1088/0967-3334/35/9/1899.

Liu Y, Koltick D, Byrne P, Wang H, Zheng W, Nie LH. Development of a transportable neutron activation analysis system to quantify manganese in bone in vivo: feasibility and methodology. Physiological Measurement. 2013;34(12):1593-1609. doi: 10.1088/0967-3334/34/12/1593. PMCID: 415406