Pros and cons of chelation for lead exposure

Here’s an interesting little tidbit of a study:

Newswise — Lead chelation therapy — a chemical treatment to remove lead from the body — can significantly reduce learning and behavioral problems that result from lead exposure, a Cornell study of young rats finds.

However, in a further finding that has implications for the treatment of autistic children, the researchers say that when rats with no lead in their systems were treated with the lead-removing chemical, they showed declines in their learning and behavior that were similar to the rats that were exposed to lead.

Chelating drugs, which bind to lead and other metals in the blood, are increasingly being used for the treatment of autism in children.

“Although these drugs are widely used to treat lead-exposed children, there is remarkably little research on whether or not they improve cognitive outcomes, the major area of concern in relation to childhood lead poisoning,” said Barbara Strupp, Cornell associate professor of nutritional sciences and of psychology and the senior author of the study, which was published in a recent issue of Environmental Health Perspectives.

Studies on the safety or effectiveness of the drugs for treating autism are similarly lacking, Strupp said.

Strupp added that to her knowledge this is the first report that shows that chelation therapy can reduce behavioral and learning problems due to lead exposure as well as the first to show that this type of treatment can have lasting adverse effects when administered in the absence of elevated levels of heavy metals.

The study used succimer (brand name, Chemet), the most widely prescribed drug for the treatment of lead poisoning. Doctors prefer succimer to other such drugs because it can be given orally on an outpatient basis, and it leaches less zinc, iron and other essential minerals out of the body. Although the Centers for Disease Control recommends chelation therapy only for children whose blood lead levels exceed 45 micrograms per deciliter, such drugs as succimer are commonly administered at much lower levels of exposure, due to concerns about lasting complications with even slightly elevated blood lead levels.

It is important to remove lead from the body as quickly as possible to prevent or lessen lasting damage to the developing brain. High-lead exposure from peeling lead-based paint can lead to coma, convulsions and even death. At lower levels, lead exposure causes attention deficits, delinquency and difficulty regulating emotions and can lower IQ scores at a rate of about one IQ point per microgram/deciliter of exposure.

The study used rats — whose mental and behavioral responses to lead exposure are similar to humans’ — and exposed them to moderate- and high-lead levels (administered via mothers’ milk). A third group — the control — was not exposed. Exposures were followed by a treatment with succimer or placebo. Immediately thereafter, the researchers conducted automated tests over six months on the rats’ attention, memory and abilities to learn and regulate emotions.

The rats with moderate-lead exposure benefited greatly from the succimer: Their test results were indistinguishable from the control test results. Rats exposed to higher lead levels showed benefits in the emotional domain: After succimer treatment, they behaved similarly to the control group. However, the treatment only slightly improved their learning deficit.

In the group that had no lead exposure but were given succimer, “we found lasting cognition and emotion-regulation [deficits] that were as pervasive and large as rats with high lead exposure,” said Strupp. She added that one possibility is that succimer, in the absence of lead, may disrupt the balance of such essential minerals as zinc and iron. “These findings raise concerns about the use of chelating agents in treating autistic children,” she said.

Succimer is the same thing as DMSA, a chelating agent that is also used by the mercury militia to chelate mercury as a “treatment” for autism. Of course, the vast majority of these autistic children do not have lead or mercury poisoning; consequently, these children would be like the control group in this experiment. Even though this experiment was done with rats, there is actually evidence that DMSA has similar effects in children. For one thing, it does not reverse the neurodevelopmental problems caused by lead toxicity. Indeed, there is even evidence that succimer might be harmful in terms of cognition.

It should always be remembered that no treatment is ever entirely without risk, and it is the height of recklessness to expose children to a drug like succimer in the absence of strong evidence for its efficacy.


  1. #1 mcewen
    December 16, 2006

    This is such a drastic and extreme step to take when there are so many other measures available. There are very few professionally qualified people to administer this form of therapy. In general this approach exploits the desperation of the parents of the child in question. I would encourage parents to try other forms of therapy with qualified professional personnel first. Best wishes

  2. #2 Bartholomew Cubbins
    December 16, 2006

    There are very few professionally qualified people to administer this form of therapy.

    I agree w/ Orac, just because someone calls it a therapy doesn’t mean that the reagent or procedure is either safe or efficacious.

    Chelation “therapy” is built upon some real science that is misdirected, a lot of speculation, and financial opportunism. Sadly, there is so little known about how well any of these chelators work in vivo, that an individual who admisters these reagents may be doing more harm than good – and I am in no way implying that the chelator could be doing any good at all.

    As a parent, it all boils down to whether you want to run the risk of damage in the hope of a gain. IMO, the implications of this risk assessment are sad and quite troubling.

  3. #3 notmercury
    December 16, 2006

    Giving DMSA or any other chelation drug when there is no evidence of mercury or lead toxicity would be like giving a kid antifungal meds in the absence of an actual fungal infection.
    Like B12 injections when there is no B12 deficiency.
    Like Lupron injections in the absence of precocious puberty.
    Like using Vancomycin in the absence of actual bacterial infection.
    Like an exorcism to treat autism.
    Like any of the other countless unproven, potentially dangerous, and abusive treatments inflicted on autistic children every day for no good reason.

  4. #4 Luna_the_cat
    December 18, 2006

    I hold out some hope that SOME people can be brought to the realisation that they are actually *hurting* the kid they want to help…

    Some won’t ever believe that. Perhaps we could make it a criminal offense to administer unnecessary medical treatments which are actually damaging to the child’s health?

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