The city tested manganese levels in well No. 10 in 2006. In this 2006 file photo, utility worker Jesse Rosas displays one of the samples. CRAIG SCHREINER

The author of a new Canadian study linking manganese in drinking water to lower intelligence levels in children said the research should prompt tougher regulation of the metal, which has been a concern in Madison’s public water supply.

Drinking water experts in Madison said the study is one of the first important scientific looks at connections between manganese and human health. But water officials also said the report should be viewed in the context of extensive efforts by the utility the last four years to reduce the city’s manganese levels.

“I think that here, when we talk about manganese, we’re seeing levels that are more appropriately an aesthetic concern,” said Joseph Grande, water quality manager for the Madison Water Utility. “We’re seeing tremendously lower levels of manganese.”

Manganese is a naturally occurring metallic element that has been a problem historically in several Madison wells. High levels are often found in public drinking water systems throughout the state and in private wells. For years, officials with the Madison Water Utility treated the presence of manganese as mostly an aesthetic problem rather than a health issue because, along with iron, it caused tap water to become cloudy and even brown or nearly black.

The utility was not alone in not treating manganese as a health problem; most other utilities followed the same policy. And the federal Environmental Protection Agency still does not set enforceable standards to regulate levels of manganese, only guidelines. The agency sets 300 parts per billion as a maximum health guideline and 50 parts per billion as a maximum for aesthetic purposes.

In Madison, before the problem started to be addressed in 2006, manganese levels in several wells were close to or above the aesthetic guideline of 50 parts per billion and one problem well, Well No. 29 on the Far East Side, sometimes tested at close to 200 ppb, still below the 300 ppb health guideline. But complaints about dirty water were frequent with some even complaining about black chunks of manganese in their ice cube trays.

Maryse Bouchard, a researcher at the University of Quebec, said one of the most surprising findings of her study was that impacts on intelligence among the children studied were apparent even after exposure to levels of manganese lower than current health guidelines.

Bouchard and other researchers studied 362 children ages 6 to 13 in eight communities and measured their intelligence quotient relative to the levels of manganese in their tap water. She studied both the impacts of manganese in drinking water and manganese in food. Using tests that measured cognition, motor skills and behavior, the researchers found the lowest IQs in children with the highest exposures to manganese, six points below children whose water did not contain manganese.

The study, published last week in the journal Environmental Health Perspectives, did not find the same impact on intelligence from manganese in food, only from that ingested in drinking water.

Bouchard said the researchers were surprised by the strength of the differences between children who were exposed to high levels and those who weren’t. And Donna Mergler, a co-author of the study and also a professor at the University of Quebec, said few environmental contaminants have shown such a strong correlation with intelligence development as manganese.

The researchers are urging environmental regulators to review guidelines for manganese safety and encouraging utilities as well as individuals to consider the use of filters to lower manganese levels. “The lower the concentration, the better,” said Bouchard.

Abigail Cantor, an expert in water systems who has conducted extensive studies on Madison Water Utility issues such as lead build-up in pipes, said the study is important but not cause for alarm in Madison. Since manganese was brought to the city’s attention by resident complaints and media reports, the utility has taken a number of important steps to lower levels including filtering problem wells, a new and more effective flushing effort, and replacing aging pipes.

“It’s very important to keep this study in perspective. I don’t think this is worthy of any kind of panic as to the water we’re drinking,” said Cantor. “We’re ahead of the game here.”

Grande said a $2 million manganese filter on Well No. 29, once dubbed the “well from Hell,” has reduced manganese levels in that well to negligible levels. Filters for other wells are being considered, he added. And some problems wells, such as Well No. 3 on the Isthmus and Well No. 10 on the West Side have been shut down.

Most important, Grande said, the Madison Water Board passed a resolution that changed the utility’s policy on manganese. If levels higher than 50 ppb are detected, steps will be taken to lower them.

“I think that board policy was a big step in giving staff guidance in terms of what is acceptable and what is not acceptable,” Grande said.