(LE ROY, N.Y.) -- Environmental activist Erin Brockovich has launched her own investigation into the mysterious illness causing facial tics and verbal outbursts among 15 teenagers in Le Roy, N.Y.
Most of the teens have been diagnosed with conversion disorder -- a psychological condition that causes physical symptoms. But Brockovich suspects ground water contamination from chemical spill more than 40 years ago may be to blame.
"They have not ruled everything out yet," Brockovich told USA Today. "The community asked us to help, and this is what we do."
Don Miller, whose 16-year-old daughter Katie still suffers from debilitating tics, said his sister contacted Brockovich for help.
"We're just trying to eliminate everything, and she wants to eliminate that it's the environment," said Miller. "It's a possibility and she wants to either prove it is or it isn't something in the environment."
Brockovich, who famously linked a cluster of cancer cases in California to contaminated drinking water inspiring an Oscar-winning movie starring Julia Roberts, said a derailed train spilled cyanide and trichloroethene within about three miles from Le Roy High School in 1970. All 15 of the affected teens -- 14 girls and one boy -- attended the school when they started showing symptoms last fall.
"When I read reports like this that the New York Department of Health and state agencies were well-aware of the spill and you don't do water testing or vapor extraction tests, you don't have an all-clear," Brockovich told USA Today.
An investigation by the New York Department of Health found, "no evidence of environmental or infection as the cause of the girls' illness," according to department spokesman Jeffrey Hammond. "The school is served by a public water system...An environmental exposure would affect many people."
Doctors also ruled out PANDAS -- a neurological disorder linked to streptococcal infections -- and the Guardasil HPV vaccine, which many of the girls did not receive, Hammond said.
The school was tested for volatile organic compounds by an independent firm, but, "people are free to pursue additional environmental testing," Hammond said.
Twelve of the teens -- all of them girls -- have been diagnosed with conversion disorder, in which the emotional response to a stressful situation is converted into physical symptoms. Three new suspected cases are still being examined. Women are more likely to get conversion disorder than men, and teens are at a higher risk than adults. But some parents want a second opinion.
"We don't really agree with it," Miller said of the diagnosis. "Down the road, who knows. But for them to give that diagnosis, they have to rule everything else out. And they haven't done that."
The National Institutes of Health has offered to help solve the puzzle. Dr. Mark Hallett, chief of the NIH Medical Neurology Branch, said the cluster of cases offers a unique research opportunity.
"We have offered our help but have not been asked for yet," said Hallett, adding that he has not yet seen any of the teens. "One of the difficulties in this is that there hasn't been a lot of attention to this problem or very much research into it, which has made it somewhat of a mysterious disorder."
Hallett said he's not surprised the teens and their families are looking for another, nonpsychological explanation.
"It always seems to be the case that patients far prefer to have a [medical] diagnosis than a psychological one," he said. "Maybe they don't see the connection; don't see how it's possible to have a tremor or tic produced just by stress."
The possibility of an environmental trigger has been bolstered by reports of similar symptoms in two teens living in Corinth, a town 250 miles from Le Roy. The girls started showing symptoms in May, around the same time they passed through Le Roy on their way to a softball tournament in Ohio.
If it is conversion disorder, there are treatments. Psychotherapy, stress management and in some cases medications can improve the symptoms. But Hallett said more research is needed to understand which approach is best.
Copyright 2012 ABC News Radio