Manganese: Environmental Exposure

Abstract

Manganese (Mn) is an essential element. However, excessive Mn exposure is toxic to humans. The optimal levels of oral exposure to Mn have not been well defined. Concerns have been expressed that data from the experimental Mn administration in animal models may be unrepresentative of the human Mn toxicity that may occur at low concentrations, raising concerns that existing animal models are of limited relevance for the risk assessment of chronic low-level Mn exposure to humans. These concerns, if vindicated, would directly impact the scientific background used to establish current guidelines. This article reviews publications relating to human exposure to Mn and potential health effects of Mn and Mn-containing inorganic compounds. The limited data available for the biologically based dose–response model point to the need for evidence, particularly on relationships between Mn, exposure routes, Mn blood levels with chronic environmental exposure, ageing, pregnancy and susceptibility factors, to improve human health risk assessments for chronic, environmental Mn exposure.