University study finds mercury levels normal in children with autism

In a large population-based study, researchers at the University of California – Davis’ MIND Institute report that after adjusting for many factors, including vaccinations, typically developing children and children with autism have similar levels of mercury in their blood streams.

Mercury is a heavy metal found in other studies to adversely affect the developing nervous system.

The study, appearing in the journal Environmental Health Perspectives, is the most rigorous examination to date of blood-mercury levels in children with autism. The researchers cautioned, however, that the study is not an examination of whether mercury plays a role in causing the disorder.

“We looked at blood-mercury levels in children who had autism and children who did not have autism,” said lead study author Irva Hertz-Picciotto, a researcher at the MIND Institute and a professor of public health sciences. “The bottom line is that blood-mercury levels in both populations were essentially the same. However, this analysis did not address a causal role, because we measured mercury after the diagnosis was made.”

The study looked at a wide variety of sources of mercury in the participants’ environments, including fish consumption, personal-care products and the types of vaccinations they received.

Of the 452 participants included in the research, 249 were diagnosed with autism, 143 were developing typically and 60 had other developmental delays, such as Down syndrome.

“Just as autism is complex, with great variation in severity and presentation, it is highly likely that its causes will be found to be equally complex. It’s time to abandon the idea that a single ‘smoking gun’ will emerge to explain why so many children are developing autism. The evidence to date suggests that, without taking account of both genetic susceptibility and environmental factors, the story will remain incomplete. Few studies, however, are taking this kind of multi-faceted approach,” Hertz-Picciotto said.