By Liz Hayes
VALLEY NEWS DISPATCH
Monday, May 2, 2005

No one questions whether mercury exposure is dangerous.

The Agency for Toxic Substances and Disease Registry, one of the federal agencies overseen by the Centers for Disease Control and Prevention, in 2003 listed mercury as the third most hazardous substance to human health, behind arsenic and lead.

The CDC notes large amounts of mercury can cause brain, nerve and kidney damage. Short-term contact with mercury can result in respiratory and intestinal problems, eye and skin irritation and increased blood pressure.

And some experts suspect mercury exposure plays a major role in autism.

Mercury's effect on young children can be more serious because their brains and nervous systems are still forming. In cases of high exposure, children could be slow in reaching developmental milestones such as walking and talking, or they could have mental retardation, vision problems, involuntary muscle contractions, seizures and lack of speech, according to the CDC.

The Environmental Protection Agency warns pregnant women and young children against eating certain kinds of fish and seafood that ingest methylmercury, an organic form of the metal. Methylmercury accumulates in the fish and can be passed on to anyone eating them.

The EPA also just released the Clean Air Mercury Rule, an initiative to reduce mercury emissions from coal-fired power plants by 70 percent. When burned, coal emits mercury, which then can be released into the atmosphere and possibly deposited into water.

According to the EPA's Toxic Release Inventory of industrial sites, there are three area power plants releasing mercury into the air: Reliant Energy's Cheswick Power Plant in Springdale, Allegheny County, Keystone Power Plant in Shelocta, Indiana County, and Allegheny Energy's Armstrong Power Station in East Franklin, near Kittanning, Armstrong County.

Other local industries releasing smaller amounts of mercury into the air, water or to landfills, include Allegheny Ludlum's Brackenridge Works, AK Steel's Butler Works and Armstrong Cement and Supply Co. in Winfield.

The autism question

The question for parents of autistic children is whether mercury caused their child's problems and, if so, how was their child exposed to the toxic metal.

The similarities between mercury poisoning and autism have led some to speculate autism isn't a separate condition, but a manifestation of mercury toxicity. The parent-led organization, Generation Rescue, believes all forms of autism and other developmental disabilities are misdiagnoses for mercury poisoning.

Many health experts now believe, but have yet to definitively prove, that autism is caused by a combination of genetic and environmental factors. One of those environmental factors could be overexposure to mercury or some other toxic chemical.

Dr. Laura Hewitson, an autism researcher with the University of Pittsburgh and Magee-Women's Research Institute, said it's clear there must be some environmental factors contributing to autism's cause. She said there needs to be more research into heavy-metal toxicity.

Dr. Scott Faber, a neurodevelopmental pediatrician at Pittsburgh's Children's Institute, said most autism cases appear to be caused by some type of environmental impact while babies are still in the womb.

"These kids have a genetic predisposition to not handling an environmental exposure," Faber said. "That exposure can be one of the chemicals in the environment. It can be heavy metals that are released into the air."

In a recently published study, researchers from two Texas universities and the University of Pennsylvania's Center for Mental Health Policy and Services Research found a correlation between the amount of mercury released into the atmosphere and the increase in autistic children in Texas' public schools.

"Capping the smokestacks to control mercury output is critical," Faber said. "(Autistic kids) are canaries in the coal mine of genetic and environmental interaction."

Studies comparing environmental mercury exposure to autism are rare, but there has been research into the correlation between the use of thimerosal in vaccines and autism. Thimerosal (pronounced thi-MEERO-sol) is a mercury-based vaccine preservative.

Unfortunately, the research has failed to satisfy parents who question whether vaccines are safe.

The CDC and National Institutes of Health in 2000 commissioned the Institute of Medicine to establish an independent Immunization Safety Review Committee to evaluate vaccine safety, including any possible links between autism and the measles, mumps and rubella (MMR) vaccine and thimerosal.

The committee's final report, released a year ago, found that neither thimerosal nor the MMR vaccine was related to autism and urged future autism research be directed away from the topic.

"The hypotheses regarding a link between autism and MMR vaccine and thimerosal-containing vaccines lack supporting evidence and are only theoretical," the report states.

However, thimerosal and vaccine opponents decried the study as biased because they said the CDC and health institutes -- pro-vaccination agencies -- funded both the study and the research of many of the committee's members. The National Vaccine Information Center, a nonprofit Virginia-based organization advocating immunization reform, questioned the committee's objectivity.

The CDC, on the other hand, says there are flaws in recent research that did find a correlation between the preservative and autism.

Still skeptical

Despite these findings, some parents remain skeptical of vaccinations. They say that, while the research doesn't prove thimerosal caused autism, it doesn't necessarily disprove it.

Marla Green, a Lower Burrell woman who has a 6-year-old autistic son, said her younger daughter, Emily, received some vaccinations, but not the MMR booster or varicella (chicken pox).

"I'm not against vaccinations, but they need to be made safer," said Green, who believes mercury toxicity contributed to her son's autism. "What's good for one might not be good for all."

Likewise, Lynn Cass, of Plum Borough, Allegheny County, believes her 7-year-old son, Alex, was in some way affected by vaccinations. She said Alex, who was diagnosed as autistic when he was 3 years old, seemed to have a regression after receiving a booster shot at age 4.

"I think Alex had a genetic predisposition for (autism), but I think there were environmental factors that came into play," Cass said.

She has decided not to give her younger son, 5-year-old Max, booster shots unless annual blood tests show his immunity to a disease is waning.

"I'm not giving it to him if he doesn't need it," Cass said. "We're not kooks who say not to vaccinate their kids. But I think you need to be cautious with what shots are given, what antibiotics are given."

Liz Hayes can be reached at lhayes@tribweb.com or 724-226-4680.