Diagnosis of manganism and manganese neurotoxicity: A workshop report.

With declining exposures to manganese (Mn) in occupational settings, there is a need for more sensitive exposure assessments and clinical diagnostic criteria for manganism and Mn neurotoxicity. To address this issue, a workshop was held on November 12-13, 2020, with international experts on Mn toxicity. The workshop discussions focused on the history of the diagnostic criteria for manganism, including those developed by the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRSST) in Quebec in 2005 and criteria developed by the Chinese government in 2002 and updated in 2006; the utility of biomarkers of exposure; recent developments in magnetic resonance imaging (MRI) for assessing Mn accumulation in the brain and diagnosing manganism; and potential future applications of metabolomics. The suggestions of the participants for updating manganism diagnostic criteria included the consideration of: i) A history of previous occupational and environmental exposure to Mn; ii) relevant clinical symptoms such as dystonia; iii) MRI imaging to document Mn accumulation in the neural tissues, including the basal ganglia; and iv) criteria for the differential diagnosis of manganism and other neurological conditions. Important research gaps include the characterization of Mn exposure and other co-exposures, exploration of the roles of different brain regions with MRI, understanding the complexity of metal ion transporters involved in Mn homeostasis, and a need for information on other neurotransmitter systems and brain regions underlying the pathophysiology of manganism.
Competing Interests: MB and UD have received funding from the International Manganese Institute (IMnI). DK is the Natural Sciences and Engineering Research Council of Canada Chair in Risk Science at the University of Ottawa. CA, DK, DM, FM, NK, NS and SR are affiliated with Risk Sciences International (www.risksciences.com), a Canadian company established in 2006 in partnership with the University of Ottawa. RSI has provided consulting services on manganese to public and private sector clients. Although IMnI contributed funding, they did not actively participate in the planning of the workshop or in the development of the workshop report. The workshop deliberations summarized in this report represent the independent views of the authors alone.
(Copyright: © Mattison et al.)