Mercury—a potent neurotoxin—has long been the whipping post of parents-turned-autism-activists, scientific evidence be damned. But a study published online yesterday in the journal Environmental Health Perspectives casts further doubt on the tenuous connection between the heavy metal and the devastating brain disorder. In what is being called “the most rigorous examination to date of blood-mercury levels in children with autism,” researchers at the Mind Institute at the University of California, Davis, examined blood-level mercury levels in 452 children, ages 2 to 5, and found no discernible difference between the mercury levels in those with autism and those developing typically. “The bottom line is that blood-mercury in both populations were essentially the same,” says Dr. Irva Hertz-Picciotto, the study’s lead investigator. Hertz-Picciotto is careful to point out that the new study hardly absolves mercury. The body rids itself of mercury after a few short months, and researchers sampled the children’s blood long after many were diagnosed with autism. Meaning, the possibility of mercury exposure triggering onset is still up for grabs. If not a smoking gun, what were the researchers looking for? Some people argue that children with autism concentrate and metabolize mercury differently than those without the disorder, says Hertz-Picciotto. This study refutes that theory.
This research also highlighted where mercury lurks in children’s lives. The scientists peered into each child’s back story searching for possible clues about mercury exposure. Questions for parents including how much fish the children ate, what kind of vaccinations they received, and whether or not they had any amalgam dental fillings.
In the end, how much fish the children dined on was far and away the biggest and most significant predictor of blood-mercury levels. Children who ate fish 2 or more times a week had 3 times the blood-mercury levels as their counterparts who sat down to a fish dinner less than once a week. Even so, parents should not shy away from feeding their children fish, says Hertz-Picciotto. Fish is brain food—its omega-3 fatty acids grease the wheels of thought and bolster brain growth—so keep fish on the kiddie menu but stick to those fish known to carry the least amount of mercury, such as canned light tuna, salmon, pollock and catfish. For more information on fish safety, visit the Environmental Protection Agency’s website.