Manganese in Drinking Water: Nuisance or Danger?
The water system that serves Roswell, Georgia, is considered a “blended water source” because the water originates from the Roswell Water Treatment Plant, which draws water from the Big Creek watershed and supplemental water purchased from a treatment plant in Alpharetta that is sourced from the Chattahoochee River.
In 2011, the water supply for the city was found to have a concentration of >0.1 mg/L of manganese. Although the U.S. Environmental Protection Agency (EPA) does not have an enforceable maximum contaminant level (MCL) for manganese, the manganese levels in Roswell at the time exceeded the EPA’s non-mandatory water quality standard of 0.5 mg/L.
Is Manganese Just a Nuisance?
Turns out, manganese can be considered both a blessing and a curse. On the one hand, it’s one of the most abundant metals on the surface of the earth, found in both groundwater and surface water—from both natural sources and as a byproduct of mining and some industrial processes.
It is also a trace mineral that is vital for the function of human systems, but only in small amounts. The reality is that while in low doses manganese is an essential nutrient, at elevated levels it can be toxic. While food is a critical source of exposure to manganese, its bioavailability—or the amount that the human body absorbs—is a greater health risk with the ingestion of drinking water that contains elevated concentrations of manganese.
Because of the discoloration that manganese causes in the water that flows from faucets in households and businesses, it has historically been considered to be simply a nuisance issue. In fact, up until 2003, the EPA did not consider manganese in drinking water to be a health risk, instead determining at the time that regulation of manganese “in drinking water does not present a meaningful opportunity for health risk reduction.”
Can Manganese Be Hazardous to Human Health?
In the intervening years, however, significant research began to uncover evidence that indeed, manganese exposure from drinking water may actually contribute to adverse health effects. And, in fact, many studies have suggested an association between exposure to manganese in drinking water and neurological issues in infants and children, such as behavior changes, lower IQ, speech and memory difficulties and lack of coordination and movement control.
In 2004, the EPA issued a Drinking Water Health Advisory (HA) level of 0.3 mg/L for chronic exposure to manganese and a one-day and 10-day HA of 1 mg/L for acute exposure. The EPA suggests 0.3 mg/L be used for both chronic and acute exposure for infants younger than six months. This is the level that was exceeded by the system in Roswell.
As for what happened to Roswell? AdEdge Water Technologies has helped many utilities and facilities solve the issue of high levels of manganese in their drinking water. In 2012, we installed a treatment system to help the City of Roswell, Georgia, to bring their iron and manganese levels to EPA standards. Today, the system is consistently meeting the effluent treatment goals of 0.05 mg/L for manganese.
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