AUSTIN, Texas - Austin has become the latest front in a mass-litigation war by a lawyer who contends that millions of Americans are being poisoned by dental fillings of mercury amalgam.

California lawyer Shawn Khorrami, in a lawsuit filed Friday in state district court in Travis County, is seeking unspecified millions of dollars from Lufkin dentist Taylor McKewen, the Texas and American dental associations and more than 30 corporations involved in manufacturing the fillings. The suit alleges that the silver-colored fillings caused severe autism in Cody Wyatt Botter, a 4-year-old Alabama boy born in Texas.

The suit was filed in Travis County because the Texas Dental Association is based in Austin.

Khorrami said he has filed more than two dozen similar lawsuits in California, Georgia, Ohio, New York and Maryland. None has gone to trial.

The American Dental Association countersued him in May for defamation via an "orchestrated campaign of lies and distortion to promote himself and his law firm." Khorrami said the association is fighting back the same way the tobacco industry did over nicotine.

McKewen could not be reached for comment, but the Chicago-based American Dental Association has long spoken for dentists and state associations in the mercury amalgam controversy, denying that the common dental fillings used for more than 170 years are dangerous.

"There is no sound scientific evidence that amalgam is harmful," said the association's dentist-director James Bramson.

Anti-mercury dental activists contend that the silver fillings contain about 50 percent mercury.

Mercury exposure has been shown to cause cancer, birth defects and nerve damage, but most scientific research on the effects of mercury in amalgam, which is used as a cementing material, have been inconclusive.

The lawsuit says Cody's mother, Darla Botter of Grand Bay, Ala., received several mercury amalgam fillings from McKewen while she was living near Lufkin and pregnant with Cody. She said he was 20 months old when he began to show signs of autism, a brain disorder of varying seriousness that can cause developmental delays lasting a lifetime.

"I know, with all my heart, that is the answer," she said.

Botter, a former secretary whose husband, Kirk, is a warehouse worker, has since had all of her mercury amalgam fillings removed at her own expense and replaced with composite plastic resin. Dentists say the resin is more expensive than amalgam and doesn't last as long.

"In this case there was malpractice," said Khorrami, who is working the Botter lawsuit with Scott Hendler, an Austin asbestos-litigation lawyer. "You shouldn't be implanting mercury amalgam fillings in the first trimester of pregnancy."

Boyd Haley, chairman of the University of Kentucky chemistry department, is the principal expert witness in Khorrami's lawsuits. Haley, who has testified to Congress against amalgam fillings, long has contended that they cause autism, Alzheimer's disease and other serious ailments.

The Alzheimer's Association doesn't agree. Nor does the Autism Society of America, a support group for parents of autistic children.

"There are currently no known causes of autism," said society spokeswoman Reneta Wisniewski. "So this might be difficult to prove."

Khorrami remains undeterred by the criticism.

"It's time that dentists realize they can be sued for placing poisonous fillings into a pregnant or nursing mother's mouth," he said.

In response to the growing legal and political concerns on the issue, the National Institutes of Health are seeking definitive answers by conducting the first large-scale studies of mercury amalgam dental fillings. Their results are expected in 2006.

Dick Stanley writes for the Austin American-Statesman.