The study, led by James Adams, professor of materials science and engineering, Arizona State University, involved 55 autistic children aged between five and 16 years, as compared to 44 non-autistic children of similar age and gender.
The autism group had significantly higher levels of lead in their red blood cells (more than 41 percent) and significantly higher urinary levels of lead (74 percent), thallium (77 percent), tin (115 percent) and tungsten (44 percent), the journal Biological Trace Element Research reports.
Lead, thallium, tin and tungsten are toxic metals that can impair brain development and function, and also interfere with the normal functioning of other body organs and systems, according to an Arizona statement.
A statistical analysis to determine levels of toxic metals in autism found that 38-47 percent of the variation of its severity was tied to the level of several toxic metals, with cadmium and mercury being the most strongly associated.
"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," says Adams.
Adams's previous study on DMSA (Dimercaptosuccinic acid), approved by FDA, for removing toxic metals found that the drug was generally safe and effective at removing some toxic metals, besides improving some symptoms of autism.
The biggest improvement was for children with the highest levels of toxic metals in their urine.