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SALT LAKE CITY — Heavy metals like mercury, lead, tungsten, tin and cadmium have long been known to be toxic, causing severe health problems and even death in high enough doses. A new study, however, has implicated these metals in contributing to autism.
The Arizona State University study looked at the blood and urine of 55 children with autism and compared it to samples from 44 unaffected children of similar ages. They found a significantly higher level of toxic metals in samples from the autistic children.
Of those in the autistic group, 41 percent more lead was found in red blood cells. Urinary levels of lead were 71 percent higher, as well as 77 percent more thallium, 115 percent more tin and 44 percent more tungsten.
All of these metals can impair brain function as well as development. They can also harm other organs in the body.
These higher levels also appear to be related to autism severity: 38 to 47 percent of the variation in severity was associated with the levels of toxic metals, with mercury and cadmium showing the strongest association.
The authors, led by ASU professor James Adams, said that limiting exposure to these kinds of metals could be helpful in treating autism. Trying to remove the metals from the body might even reduce symptoms.
"We hypothesize that reducing early exposure to toxic metals may help ameliorate symptoms of autism, and treatment to remove toxic metals may reduce symptoms of autism; these hypotheses need further exploration, as there is a growing body of research to support it," the study says.
The study was published in the latest issue of Biological Trace Element Research. It was funded by the Autism Research Institute and the Legacy Foundation. It builds on work that Adams published in 2009, where he showed that levels of toxic metals were associated with how severe a case of autism was in children ages 3 to 8 years old.