Manganese

Manganese is a metal found naturally occurring in many types of rocks. Pure manganese, which is silver in color, does not occur naturally. In nature, manganese is found combined with other elements like oxygen, sulfur, and chlorine. Manganese is naturally found in most foods.

Uses
Manganese is used in steel production to "improve hardness, stiffness, and strength," and in a gasoline additive that improves the octane rating of gas. Manganese can also be used to decolorize glass.

In the Environment
Manganese can be released into air, soil, and water when manganese-based products are manufactured, used, and disposed of. In water, manganese attaches to particles and settles to the bottom. In soil, manganese may behave different based on the chemical state of the manganese and the type of soil. The manganese-containing gasoline additive is also a source of manganese in the environment. This additive degrades quickly when exposed to sunlight, releasing manganese.

In Sewage Sludge
Manganese may also enter the environment via sewage sludge applied on land. In the Targeted National Sewage Sludge Survey, a 2009 test of 84 samples of sewage sludge from around the U.S., the EPA found manganese in every sample in concentrations ranging from 34.8 to 14,900 parts per million. There is no legal limit on manganese in sewage sludge applied to land.

Human Exposure
Humans are mostly exposed to manganese in food or nutritional supplements. Foods like grains, beans, nuts, and tea are rich in manganese. Some people are exposed to manganese on the job. For example, welders and workers in steel factories might be exposed to high levels of manganese. Manganese is also found in groundwater, drinking water, and soil.

Regulations for Drinking Water
The EPA has set a secondary standard on manganese in drinking water at 0.05 mg/L. This is merely a recommendation and not enforceable. According to the EPA, a child can safely be exposed to manganese in drinking water at concentrations of 1 mg/L for up to 10 days without any adverse effects. The EPA also established a lifetime exposure of 0.3 mg/L manganese is "not expected to cause any adverse effects." Last, the FDA has determined that the manganese concentration in bottled drinking water should not exceed 0.05 mg/L.

Health Effects
In small amounts, manganese is an essential nutrient that humans need to stay health. However, at high levels of exposure, manganese can impact the nervous system. "These health effects include behavioral changes and other nervous system effects, which include movements that may become slow and clumsy. This combination of symptoms when sufficiently severe is referred to as "manganism". Other less severe nervous system effects such as slowed hand movements have been observed in some workers exposed to lower concentrations in the work place." Animal studies have also shown reproductive effects from high oral doses of manganese.

In extremely high levels, manganese may "produce undesirable effects on brain development, including changes in behavior and decreases in the ability to learn and remember."

Related SourceWatch articles

 * Biosolids
 * Sewage sludge
 * Food Rights Network

External resources

 * Agency for Toxic Substances & Disease Registry, ToxFAQs for Manganese

External articles

 * Sheryl Ubelacker, Manganese in water can harm kids' IQ: study, Metro News, September 20, 2010.
 * Lynne Peeples, Metal Pollution Tied to Parkinson's Disease, Reuters, October 28, 2010.