This theory hypothesizes that autism is associated with mercury poisoning, based on perceived similarity of symptoms and reports of mercury or its biomarkers in some autistic children. This view has gained little traction in the scientific community as the typical symptoms of mercury toxicity are significantly different from symptoms seen in autism. The principal source of human exposure to organic mercury is via fish consumption and for inorganic mercury is dental amalgams. The evidence so far is indirect for the association between autism and mercury exposure after birth, as no direct test has been reported, and there is no evidence of an association between autism and postnatal exposure to any neurotoxicant. A meta-analysis published in 2007 concluded that there was no link between mercury and autism.
