VOA标准英语2010年-Researchers Say Several Factors Contri

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Scientists don't know what causes autism, but besides a genetic¹ predisposition, they are now focusing on environmental exposure, or a combination of the two.

A conference on autism is taking place in (the eastern state of) Pennsylvania. The aim is to help teachers and parents deal with  challenges faced by children with autism.  The disease affects a person's ability to communicate and interact but symptoms vary. New studies are challenging formerly² held beliefs that autism is passed down genetically³. Now some experts say a child's environment has to be taken into account.

Max is a 10-year old boy with autism.  Recently, his mother called on US lawmakers to allocate⁴ more funds to find the cause and a cure.

"As families of children with autism, we each struggle with the why. I do not believe we can come to simple conclusions when it comes to the cause and effects of such a complex disorder⁵ as autism," Mary Moen states.

Autism is a set of disorders⁶, along a wide spectrum⁷, that affects a person's ability to respond socially or form relationships. It is diagnosed more often in boys than girls.

Scientists don't know what causes it, but besides a genetic predisposition, they are now focusing on environmental exposure, or a combination of the two.

At the University of California at Davis, Dr. Isaac Pessah is researching the impact of the environment on brain development and autism. "We must identify which environmental exposures and combination of exposures are contributing to increased overall risk in the population," he says, "and identify the most susceptible⁸ groups."

Dr. Pessah says chemicals used commercially -- there are some 80,000 -- could affect a child's developing brain.

Paul Anastas of the US Environmental Protection Agency [EPA] argues that improvements in diagnosing autism cannot be solely⁹ responsible for the dramatic increase in autism cases reported worldwide.  "We often get into this discussion about is this environment or is this genetics. When I think, there is a growing body of knowledge which says it is not one or the other. Our genetics cannot change this quickly in order to explain the increase in incidence," he said. "What we are saying is that it's likely an interaction of the environment and genetic susceptibility."

Heavy metals, such as lead, and products like insecticides have recently been linked to abormalities in newborns and attention deficits¹⁰ in toddlers.

Dr. Bruce Lanphear is at Cincinnati Children's Hospital Medical Center. "There is emerging evidence that a whole host of new environmental chemicals, many of them routinely found in pregnant women and children - such as Bisphenol A, flame retardants, pesticides¹¹, phthialates, and airborne pollutants," he explains "are associated with intellectual deficits or behavioral problems."

The U.S. Centers for Disease Control says a form of autism may affect one in every 150 American children.

Parents of children with autism say better services and resources for the children are essential. But most important is finding the cause of the disease so it can be prevented or cured.