In the months after Joseph Alexander Counter was born in 1996, he appeared to progress normally. He had met all his developmental milestones and by the age of 20 months had a growing vocabulary, says plaintiffs’ attorney Andrew Waters of Dallas’ Waters & Kraus. “He was able to say mama and dada and fire truck, sort of,” Waters says. “But then he lost all of his language, and the only way he could communicate was by screaming.”

The boy was diagnosed with autism and then tested and found to have high levels of mercury exposure. Seemingly, there was no explanation for this. As an infant, “Jac” – the boy’s nickname, based on his initials – hadn’t been unusually exposed to any heavy metals. But as the boy’s parents, Joseph and Theresa Counter, began researching Web sites and contacting support groups for parents of autism, a theory developed.