Is Manganese safe?

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Is Manganese Safe? An Analysis of Current Research

Manganese Intake Levels and Safety

Tolerable Upper Intake Levels for Manganese

Manganese is an essential nutrient required for various physiological functions, but its safety at higher intake levels has been a subject of extensive research. The European Food Safety Authority (EFSA) has established a safe intake level of 8 mg/day for adults, including pregnant and lactating women, and between 2 and 7 mg/day for other population groups. This recommendation is based on observed dietary intakes from natural sources, as there is insufficient data to establish a precise upper limit for manganese-induced neurotoxicity.

Health Risks from Environmental and Dietary Exposure

Neurotoxicity and Manganese Exposure

Excessive manganese intake, particularly from environmental sources such as contaminated water, has been linked to neurotoxicity. Studies have shown that high levels of manganese in drinking water can lead to symptoms of neurotoxicity, including cognitive and motor dysfunctions. In industrial settings, chronic exposure to manganese-laden dust has been associated with neuropsychological changes resembling Parkinson's disease. These findings underscore the importance of monitoring manganese levels in both environmental and dietary sources to prevent adverse health effects.

Regional Health Risks

In regions like Huangxing Town, Middle China, the ingestion of manganese through contaminated groundwater and vegetables poses significant health risks. Hazard quotient (HQ) values exceeding 1 indicate potential health risks, necessitating pollution control measures to ensure safe water and food supplies. Similarly, in Bangladesh, manganese levels in tube well water often exceed recommended safety limits, posing non-carcinogenic health risks to both children and adults.

Manganese in Animal Feed

Safety of Manganese Additives

Manganese is also used as a nutritional additive in animal feed. Studies have shown that manganese chelates of lysine and glutamic acid are safe for chickens at levels up to 150 mg Mn/kg feed, with a margin of safety of 5.5. This safety level can be extrapolated to all animal species, provided that the maximum authorized levels in the EU for total manganese in feed are not exceeded. Similarly, manganese(II)-betaine complex has been deemed safe for all animal species at specified levels, although it is considered a dermal and respiratory sensitizer due to the presence of nickel.

Monitoring and Recommendations

Biomarkers and Monitoring

Monitoring manganese exposure is crucial for preventing toxicity. Serum manganese concentrations, combined with brain MRI scans and neurofunctional tests, are effective methods for assessing excessive manganese exposure. For patients receiving long-term home parenteral nutrition (HPN), a recommended manganese supplementation level of 55 µg/day is based on moderate-strength evidence, although further high-level studies are needed to refine these guidelines.

Conclusion

Manganese is essential for health but poses risks at high intake levels. Safe intake levels have been established, but regional and environmental factors can lead to excessive exposure, necessitating careful monitoring and regulation. In animal feed, manganese additives are generally safe within specified limits. Ongoing research and refined monitoring methods are essential to ensure manganese safety across different populations and environments.