J. B. Adams et al.

This study investigates the possible relationship of the severity of autism to the relative body burden of toxic metals.

… The various correlation analyses found that overall there were multiple positive correlations between the severity of autism and the urinary excretion of some toxic metals (both before and after taking DMSA). Lead (after DMSA) and antimony (at baseline) had the most consistent effect, but other metals were also important.

… Different metals are significant for the different scales, and this partial dis- agreement is probably due to two factors. First, the severity scales are not identical … Second, it should be noted that the high correlation between urinary excretion of many of the metals … makes it difficult to separate the effect of one metal from another … Thus, it is probably best to not overinterpret the results in terms of a particular metal, but to instead interpret them as evidence of the general role of toxic metals in relation to the severity of autism. Since oxidative stress and thiol metabolic disturbances have both been described in the autism population, it is likely that these play a role in both relative burden and susceptibility to heavy metals. And since heavy metal exposure generates oxidative stress and thiol depletion, the potential etiological role of metal cations in generating autism symptoms should be further studied.