Manganese dosimetry: species differences and implications for neurotoxicity

Area of Science:

• Environmental toxicology
• Neuroscience
• Mineral metabolism

Background:

• Manganese (Mn) is an essential mineral with potential for toxicity at high doses.
• Excessive manganese accumulation can cause neurological, reproductive, and respiratory adverse effects.
• Manganese-induced neurotoxicity (manganism) presents as a parkinsonism-like motor dysfunction syndrome in humans.

Purpose of the Study:

• Review the essentiality and toxicity of manganese.
• Examine contemporary studies on manganese dosimetry, blood-brain barrier transport, and CNS distribution.
• Clarify health risks associated with manganese exposure and identify susceptible populations.

Main Methods:

• Literature review of studies on manganese dosimetry, transport, and distribution.
• Analysis of factors influencing manganese toxicokinetics, including interactions with other elements and oxidation state.
• Comparison of species differences in manganese toxicokinetics and neurological effects.

Main Results:

• Contemporary studies enhance understanding of manganese health risks by detailing exposure conditions leading to elevated CNS concentrations.
• Manganese transport to the brain can occur via the olfactory nerve following inhalation.
• Nonhuman primates exhibit CNS effects similar to humans, unlike rodents.

Conclusions:

• Manganese disposition and toxicity are influenced by route of exposure, interactions with other elements, and oxidation state.
• Potentially susceptible populations (fetuses, neonates, impaired hepatic function, altered iron/manganese intake, aging) may face increased manganese toxicity risk.
• Further research into manganese dosimetry and transport is crucial for accurate risk assessment.