Manganese in Drinking Water

Information Regarding Manganese Levels in Amherst Drinking Water

Manganese is a naturally-occurring element found in rocks, soil, air, groundwater, and surface water. It is an essential nutrient that is used by the body for metabolism, immune system function, digestion, bone strength, and as a cofactor in many enzymes. Chronic exposure to elevated levels of manganese can lead to health problems, though, and the Massachusetts Department of Environmental Protection (MassDEP) is conducting a new outreach initiative to raise awareness regarding manganese in drinking water. Through this initiative, the Town of Amherst is providing the following information to residents.

How are people exposed to manganese?
Most manganese exposure in the general population comes from food. Manganese is commonly found in the food we eat, including nuts, legumes, seeds, grains, and green leafy vegetables. (One cup of enriched white rice contains 0.75 milligrams of manganese.) In particular, grains and beans are significant sources of manganese. The USDA recommended daily allowance of manganese for adults is 1.8-2.3 milligrams per day.

Formula-fed infants may consume relatively high levels of manganese levels if the formula powder contains elevated manganese and it is prepared with water that also contains manganese. In addition, infants may have more difficulty processing manganese than older children and adults because their gastrointestinal and metabolic organ systems may not be completely developed. Infants and young children may absorb more and excrete less manganese than older children and adults.

What health effects are associated with exposure to elevated levels of manganese?
While low levels of manganese in the diet are important for good health, exposure to elevated levels can lead to adverse neurological effects. Several recent, limited studies suggested an association between elevated levels of manganese in drinking water and behavioral and neurological effects in children. Therefore, as a precaution, it is prudent to limit manganese levels in drinking water in order to protect sensitive populations (infants and young children).

What are the standards for manganese in drinking water?
Manganese is currently included on federal and state Secondary Maximum Contaminant Level (SMCL) lists for drinking water. SMCLs are based on aesthetic considerations, not health considerations, and the SMCL for manganese is 0.05 milligrams per liter (mg/l). Manganese levels above the SMCL can lead to water discoloration, staining of fixtures, and/or a bitter, metallic taste. In addition, the U.S. Environmental Protection Agency (USEPA) has established public health advisory levels for manganese in drinking water.

Over a lifetime, the USEPA recommends that people consume water with manganese levels less than 0.3 mg/l, and less than 1.0 mg/l over short-term periods. Infants less than 1 year of age should not be given water with manganese levels above 0.3 mg/l, nor should formula be made for infants with that water for longer than 10 days.

What levels of manganese are in Amherst drinking water?
Town of Amherst municipal drinking water sources are tested annually for manganese levels. In 2013, manganese levels in our sources ranged from less than 0.020 mg/l to 0.043 mg/l. These levels are below both the SMCL and USEPA health advisory levels. We will continue to monitor our sources on an annual basis, and if necessary, we will take appropriate steps to limit manganese levels in drinking water.