Government scientists have determined that long-term exposure to manganese can cause mental disabilities and emotional problems, especially in kids.

The preliminary results, to be released today, found average manganese levels at least 70% higher than what the EPA considers safe for long-term exposure outside Warren Elementary School in Marietta, Ohio, and Neale Elementary School in Vienna, W.Va. The schools are about 10 miles from each other.

In both cases, EPA officials stress the results are preliminary, and that drawing conclusions about long-term health dangers from a small number of samples is impossible. Regulators will take at least six more samples at the schools. "This entire effort has been about sound science, transparency and the responsibility EPA has to ensure our children are protected where they play and learn," says EPA spokesman Brendan Gilfillan.

The results worry experts. "That's definitely something we don't want to see in the air near schools," says Gina Solomon, a senior scientist for the Natural Resources Defense Council.

One reason: Manganese can accumulate in the soil. That means kids at elementary schools can also be exposed by playing in the dirt, Solomon says.

"I'm very concerned," says Stephen Lester, science director of the Center for Health, Environment & Justice, a group that focuses on children and schools. "It speaks volumes to the need to address these problems."

Manganese is often emitted by metalworking plants, Solomon says. If monitoring continues to show problems, she says, the "priority is figuring out where it's coming from" and reducing the emissions. That's the hope of Tom Gibbs, superintendent of the Ohio school's district. "We're optimistic that the monitoring will result in some action," he says. "This is something that the community is going to need to work together to address."

Neale Principal Michael Fling says he plans to let the parents of his 389 students know later this week what the EPA is finding. "I'm glad that they're doing it," Fling says of the EPA. "There are a lot of people in the community who had questions."

The 63-school monitoring effort is part of a $2.25 million EPA program launched in response to a USA TODAY investigation that identified hundreds of schools where chemicals appear to saturate the air.