Studying individual school districts in Texas, the epidemiologists found that those districts with the highest levels of mercury in the environment also have the highest rates of special-education students and autism diagnoses.
The study does not prove that mercury causes autism, cautioned the lead author, Raymond Palmer of the University of Texas Health Science Center in San Antonio, but it provides "provocative" clues that should be investigated.
"Mercury is a known neurotoxin," said Dr. Isaac Pessah of the University of California, Davis' M.I.N.D. Institute, who was not involved in the study. "It's rather intriguing that the correlation is so positive. It makes one worry."
California has the highest environmental burden of mercury of any state and it has what appears to be the highest rate of autism, although some critics attribute this perceived high rate to enhanced surveillance associated with the state's special-education program.
The study, which will appear in the peer-reviewed journal Health & Place, found that every 1,000 pounds of mercury released into the environment produced a 43 percent increase in special-education services and a 61 percent increase in the autism rate.
Bonnie - Interesting that the study did not include mercury intake from vaccinations.