Is Manganese safe in drinking water?

Elevated levels of manganese in drinking water are associated with adverse neurological effects in infants and children, including impacts on brain development, learning, behavior, lower IQ, speech, memory difficulties, and lack of coordination.

Why here

Drinking water is a direct route of ingestion, and manganese bioavailability is higher from water than from food. Infants and young children are particularly vulnerable due to developing brains and higher water intake relative to body weight, especially for formula-fed infants.

What would have to be true

Above 0.3 mg/L (300 µg/L) for infants younger than 6 months (US EPA health advisory); above 0.12 mg/L (120 µg/L) (Health Canada maximum acceptable concentration).

Long-term consumption of drinking water with high levels of manganese can lead to nervous system impacts in adults, including behavioral changes and movement difficulties, resembling Parkinson's disease.

Why here

Drinking water is a direct route of ingestion, and manganese bioavailability is higher from water than from food.

What would have to be true

Above 0.3 mg/L (300 µg/L) for lifetime exposure (US EPA health advisory).

Manganese in drinking water can cause aesthetic issues such as metallic taste, discoloration (black or brown water), and staining of plumbing fixtures, laundry, and other surfaces.

Why here

Manganese compounds can precipitate out of solution in drinking water, leading to visible and taste-related issues in the water itself and on surfaces it contacts.

What would have to be true

Above 0.05 mg/L (50 µg/L) (US EPA Secondary Maximum Contaminant Level).

Chronic ingestion of manganese in drinking water at elevated concentrations can lead to neurological problems, including impaired learning and behavior, particularly in infants and young children.

Why here

Drinking water is a common household exposure route, and manganese can be present naturally or from plumbing, leading to direct ingestion by household members.

What would have to be true

Ingestion of drinking water with manganese concentrations above 0.3 mg/L for lifetime exposure, or above 0.3 mg/L for infants up to 6 months for more than 10 days per year.

Elevated levels of manganese in household dust are associated with increased manganese levels in children's hair, suggesting a potential for neurological impacts from chronic inhalation exposure in the home.

Why here

Household dust is a pervasive component of indoor air, and children, who spend significant time indoors and engage in hand-to-mouth behaviors, are particularly susceptible to exposure through incidental ingestion and inhalation of settled dust.

What would have to be true

Chronic inhalation and incidental ingestion of manganese-containing household dust, particularly in homes with higher dust levels, which can be influenced by ambient manganese from nearby industrial sources.

Some commentators argue that inhalation of vaporized manganese during showering in manganese-contaminated water may lead to permanent neurological effects, even at levels considered safe by the EPA, though this is not scientific consensus.

Why here

Showering is a daily household activity where water containing manganese could be aerosolized and inhaled.

What would have to be true

Chronic inhalation of manganese vaporized from shower water containing elevated manganese levels, over a decade or more.

The other side

Manganese is generally poorly absorbed through the skin, and this hypothesis is based on animal studies and a review of medical literature, not established human clinical trials, and was published in a journal for ideas.