Manganese: A Hazardous Air Pollutant?

Manganese is an essential element for healthy human functioning, particularly for bone health and metabolism. However, overexposure to manganese can be harmful to humans. Manganese is a byproduct of some industrial processes and is released into the air, soil, and water. Inorganic manganese compounds can exist in the air as aerosols or suspended particulate matter. Studies have shown that long-term exposure to high levels of air manganese may result in mild deficits of cognitive function in adult populations. Therefore, it is important to understand the potential hazards of manganese as an air pollutant and its effects on human health.

Manganese is released into the air, soil, and water as a byproduct of some industrial processes

Manganese is an essential element for healthy human functioning, particularly for bone health and fat and carbohydrate metabolism. However, overexposure to manganese may be harmful to humans. Manganese is released into the air, soil, and water as a byproduct of some industrial processes.

Inorganic manganese compounds can exist in the air as aerosols or suspended particulate matter. Car exhausts that use MMT-containing gasoline, for example, have been found to emit manganese in inorganic phosphate and sulfate forms. In addition, manganese dioxide can also be detected in smaller amounts. MMT, or Methylcyclopentadienyl manganese tricarbonyl, is a fuel additive developed in the 1950s to increase the octane level of gasoline and improve its antiknock properties.

Manganese released into the environment through industrial processes has been the subject of several environmental studies. These studies have focused on populations living close to industries, such as manganese alloy production plants, as well as rural populations exposed through contaminated well water. For example, a study in southwest Quebec, Canada, found that a community near a former manganese alloy production plant had experienced environmental manganese pollution. Similarly, a study in Brazil examined mothers and children exposed to manganese from a ferro-manganese alloy plant.

Long-term exposure to high levels of manganese in the air may result in mild deficits in cognitive function in adult populations. Studies have found associations between manganese exposure and performance on tests of working and visuospatial memory, verbal skills, and abstract reasoning. For instance, a study in Ohio, USA, found that adults residing in two towns with high levels of airborne manganese from industrial sources exhibited significant relationships between manganese exposure and cognitive function.

Inhaled manganese from car exhaust is a potential contributor to exposure

Manganese is an essential element for healthy human functioning, especially for bone health and fat and carbohydrate metabolism. However, overexposure to manganese may be harmful to humans. Inorganic manganese compounds can exist in the air as aerosols or suspended particulate matter.

Manganese is a byproduct of some industrial processes and is released into the air, soil, and water. Environmental studies have often included rural and suburban populations living close to industries, as well as rural populations exposed through contaminated well water.

One study, conducted by Mergler et al. (1999), focused on a community in southwest Quebec, Canada, near a former manganese alloy production plant. The study found that due to the presence of MMT in gasoline in Canada, inhaled manganese from car exhaust is a potential contributor to manganese exposure in the population studied. MMT is a fuel additive developed in the 1950s to increase the octane level of gasoline and improve antiknock properties. Exposure to MMT is primarily through inhalation or oral pathways, although occupational exposure for gasoline attendants or mechanics may be more significant through dermal absorption.

In addition to the study by Mergler et al., other research has also explored the health effects of inhaled manganese. For example, Solis-Vivanco et al. (2009) reported an association between Mn levels in the air and poor performance on cognitive tests, including a negative association between Mn levels and Digit Span recall. Similarly, a study by Menezes-Filho et al. (2011) found that Mn levels in hair were negatively associated with scores on cognitive ability tests among mothers exposed to Mn from a ferro-manganese alloy plant.

Manganese is an essential element for healthy human functioning, especially for bone health

Manganese is a naturally occurring element that can be found in the air, water, soil, and food sources. While it is most well-known for its industrial uses, it is also an essential nutrient for human health. Manganese is a trace mineral, which means that our bodies only need a small amount to function properly. However, if we do not get enough manganese, certain chemical processes in our bodies may not work correctly.

Manganese plays a crucial role in maintaining bone health. It assists enzymes that are responsible for building and maintaining bones. Animal studies have shown that a deficiency in manganese can lead to reduced bone density and impaired bone formation. While human studies on this topic have been limited, some observational studies have found lower blood levels of manganese in individuals with osteoporosis. Additionally, manganese has been found to support bone mineral density when combined with other essential nutrients like calcium, zinc, and copper.

Manganese is also important for maintaining healthy brain function and treating specific nervous disorders. It has antioxidant properties and plays a role in the function of superoxide dismutase (SOD), which helps protect against free radicals that can damage brain cells. Manganese can also bind to neurotransmitters and stimulate faster or more efficient movement of electrical impulses throughout the body, thereby improving brain function. However, it is important to note that excessive amounts of manganese can have negative effects on the brain and nervous system.

The recommended daily intake of manganese for adults is 2.3 mg for men and 1.8 mg for women, with a Tolerable Upper Intake Level of 11 mg for adults over 19 years of age, including pregnant and lactating women. Manganese can be found in a variety of food sources, including whole grains, seeds, nuts, legumes, beans, leafy green vegetables, tea, and even spices. However, it is important to monitor manganese intake, especially when taking supplements, to avoid potential health risks associated with excessive consumption.

Overexposure to manganese may be neurotoxic to humans

Manganese (Mn) is the twelfth most abundant element on Earth and is necessary for maintaining human health and function. It is present at low concentrations in a variety of dietary sources, including legumes, rice, nuts, whole grains, seafood, seeds, chocolates, and teas. Consuming small amounts of Mn daily is important for maintaining a variety of physiological functions in the body, such as defence against oxidative stress, proper development, digestion, and immune response.

However, with the increased use of Mn in various industries, the risk of overexposure to this transition metal has also increased. Overexposure to manganese may be neurotoxic to humans. Mn toxicity can occur through occupational exposure, air pollution, nutritional sources, contaminated foods, infant formulas, and water, soil, and air contamination. Inhalation and oral ingestion are the primary pathways of exposure. Mn released into the air from the combustion of gasoline containing the fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) is a significant source of exposure, especially in high-traffic areas.

The health effects of Mn overexposure include clinical signs and symptoms resembling Parkinson's disease, oxidative stress, inflammatory response, transporter dysregulation, and neurodegeneration. For example, exposure to Mn has been shown to cause neurodegeneration by increasing the release of misfolded αSyn, which leads to a pro-inflammatory and neurodegenerative response, ultimately resulting in dopaminergic neurotoxicity.

Biomarkers of Mn exposure in humans include toenail, blood, and urine samples, which can be used to assess the level of exposure and potential health risks associated with Mn overexposure.

Studies have found a significant relationship between Mn exposure and performance on memory and verbal skills

Manganese (Mn) is a metal that is essential for various biological processes in the human body. However, overexposure to manganese can have serious health consequences. Occupational exposure is a concern, particularly for gasoline attendants or mechanics, who may absorb manganese through dermal absorption. In addition, inhaled manganese from car exhaust is a potential contributor to manganese exposure.

Several studies have examined the effects of manganese exposure on cognitive performance, particularly in the areas of memory and learning. One study found that workers exposed to manganese performed worse on tasks requiring processing speed, attention, working memory, reaction time, cognitive control, and visual attention. Another study on non-human primates found that chronic exposure to manganese led to impairments in working memory performance, with a significant inverse relationship between brain Mn concentration and memory task performance.

The effects of manganese exposure on verbal learning and memory have also been investigated. One study on Mexican children living in a Mn-mining district found that those exposed to manganese had higher hair and blood Mn levels and lower scores on the Children's Auditory Verbal Learning Test (CAVLT). Hair Mn levels were inversely associated with CAVLT subscales evaluating long-term memory and learning. These results suggest that manganese exposure negatively impacts children's memory and learning abilities.

Overall, the studies reviewed provide evidence of a significant relationship between Mn exposure and performance on memory and verbal skills. However, it is important to note that the nature of cognitive deficits associated with manganese exposure is not yet fully understood, and more research is needed to clarify the relationship between Mn exposure and cognitive functioning.

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