Chelation & Autism · Jul 27, 09:41 AM

The following is a preview of an article by James R. Laidler, M.D., soon to be published on Autism Watch, reproduced by permission of the author.

Chelation & Autism
by James R. Laidler, M.D.

Can chelation help autism?

Chelation is a legitimate medical therapy for disorders caused by an excess of certain metals. Copper, iron, mercury, arsenic and lead are all metals that can cause toxicity disorders that are successfully treated by chelation. Since about 1985, when the idea that autism might be caused by mercury poisoning first arose, many practitioners and groups have promoted chelation as a treatment for autism.

Clearly, the first question that must be settled is whether autism is caused by mercury (or other metal) toxicity—if it is not, then there is no point in treating it with chelation. Unfortunately, this question has become one of many “hot topics” in autism, with much heat and emotion obscuring the scientific data. The first step, then, is to look past the emotion and political maneuvering and examine the data.

When it was first proposed, the idea that autism might be due to mercury poisoning showed a good deal of promise. After all, mercury is a well-known neurotoxin and, additionally, was used as a preservative (thimerosal) in the vaccines children received. With a degree of biological plausibility and a known exposure, the next step was to look for epidemiological data.

Unfortunately, well-designed studies take a while to complete and publish. This delay left an information vacuum that a number of people immediately began to fill with assertions that autism definitely was or certainly was not caused by the thimerosal in vaccines. This did not make any progress toward settling the question, but instead polarized the issue before the arrival of any real data.

Lurking in the background, undetected in the tumult, were data that could have pointed the way. At least two countries—Canada and Denmark—had removed thimerosal from their vaccines in the 1990’s (Canada 1994, Denmark 1992) and yet had both experienced rises in autism prevalence similar to those in the US and UK. Additionally, while the childhood vaccines in the US included three (DTP, HiB, HepB) with thimerosal, in the UK, for the past two decades, only the DTP vaccine contained thimerosal. This meant that, despite having a constant thimerosal exposure for nearly twenty years, children in the UK experienced the same rise in autism prevalence.

In 2003, the first study , from Denmark, showed that the prevalence of autism in that country had risen steeply even though thimerosal had been removed from vaccines in the early 1990’s. This study was greeted by howls of outrage from some that advocated the connection between thimerosal/mercury and autism—the authors were roundly disparaged and their integrity and objectivity were impugned. This did not change the fact that the autism prevalence in Denmark has continued to rise, following the same pattern as autism in the US and the UK.

In September 2004, a study from the UK showed no association between thimerosal exposure and autism . At the same time, a review of ten epidemiological studies of autism and thimerosal found that the few studies that found an association between thimerosal exposure and autism had serious methodological flaws. Chief among these flaws was using the Vaccine Adverse Event Reporting System (VAERS) as a source of data.

The chief problem with the VAERS data is that reports can be entered by anyone and are not routinely verified. To demonstrate this, a few years ago I entered a report that an influenza vaccine had turned me into The Hulk. The report was accepted and entered into the database.

Because the reported adverse event was so… unusual, a representative of VAERS contacted me. After a discussion of the VAERS database and its limitations, they asked for my permission to delete the record, which I granted. If I had not agreed, the record would be there still, showing that any claim can become part of the database, no matter how outrageous or improbable.

Since at least 1998 (and possibly earlier), a number of autism advocacy groups have, with all the best intentions, encouraged people to report their autistic children—or autistic children of relatives and friends—to VAERS as injuries from thimerosal-containing vaccines. This has irrevocably tainted the VAERS database with duplicate and spurious reports.

Testing for mercury

What, then, about the parents who have tested their children and found their mercury levels high? These children may have a legitimate problem with mercury poisoning…if the testing is valid. While laboratory accuracy—and cost—is an issue with many of the “mail-order” labs, a more serious problem is the manner in which the specimen is collected.

Many practitioners who advocate chelation routinely use “provoked” or “stimulated” excretion studies. To do this, they administer a dose of a chelating agent (more about them later) and test the urine a few hours later. This practice will routinely and predictably elevate the urine mercury level to several times the “unprovoked” or “unstimulated” level. Since the normal values listed on the laboratory report are for “unprovoked” specimens, the results will be much higher than normal and can appear alarming.

The cost of many of the mail-order labs is also a significant concern. A brief survey of some of the bigger mail-order labs revealed that they charge between $175 and $300 for a “panel” of urine metal tests, including mercury. The local hospital lab charges $35 for a urine mercury test. In most cases, the other metals included in the “panel” or of little or no use—there is no research or clinical data that connects some of these other metals to any disorder whatsoever.

Another questionable practice is the use of fecal mercury levels. The mercury in feces is a combination of ingested mercury (minus the amount that was absorbed) and any mercury excreted into the feces (usually in the bile)—there is no way to truly know how much mercury is being excreted without knowing the amount ingested and the amount absorbed. One thing that is certain, however, is that the fecal mercury level will be higher than the actual amount of excreted mercury, because of the mercury in the food we eat, the water we drink and the air we breathe.

This brings us (at long last) to chelation.

Chelation—what it is and how it works

Chelation works by using a compound has a stronger attraction (affinity) for mercury than the tissues of the body. Since mercury has a very strong affinity for sulfur, all the effective mercury-chelating agents contain sulfur. This does not mean that any sulfur-containing molecule can act as a chelator, since body tissues also have sulfur-containing components, which are what the mercury binds to. An effective chelator needs to have a higher affinity than body tissues.

This simple fact eliminates some of the compounds that are being touted as chelating agents for mercury. Glutathione, for instance, which has a sulfur-containing amino acid, is not sufficiently greater in its affinity for mercury than the body tissues to be an effective chelator. Another widely used chelating agent, EDTA, not only has little affinity for mercury, but is also not absorbed when taken orally—it must be given intravenously.

The two agents that are most effective for chelating mercury are 2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercaptopropane-1-sulfonate (DMPS) . DMSA has been widely used in the US—primarily for lead poisoning—and has a good safety record. DMPS has a long history of use in the Soviet Union, but has more toxicity problems. DMPS is popular with some practitioners because it causes a very large rise in mercury excretion, primarily by prompt clearance of kidney mercury stores, making it very useful for “provoked” mercury testing.

DMPS is not approved by the USFDA for any purpose, primarily because it offers no medical advantages over DMSA and is more toxic. Both can be given by mouth, but only DMPS is available in an intravenous form. Given that there is little or no difference in their effectiveness, a practitioner who wants to use DMPS should be viewed with suspicion.

The sulfur-containing groups in DMSA (there are two) are mercaptans, relatives of the odorant that is put in natural gas to make it smell bad. In short, it stinks. This can be a problem not only for the child who has to take it, but also for the entire family, as urine that contains DMSA will also have a foul, sulfurous smell. While some manufacturers claim to have overcome the smell “issue”, if the urine doesn’t smell foul, there is no DMSA being excreted and, therefore, no chelation happening.

One preparation that deserves comment is transdermal DMSA (or DMPS)—a cream or ointment that is rubbed onto the skin, presumably to chelate mercury. Both DMSA and DMPS are highly water-soluble and do not dissolve well in fat or oil, which means that they most likely won’t be absorbed through intact skin. It is interesting to note that none of the individuals or corporations selling this preparation has—to my knowledge—performed the simple test necessary to prove that it is absorbed. In the absence of this simple bit of data, it must be assumed that it is not absorbed.

Lipoic acid—a sulfur-containing fatty acid—has also been touted as a chelating agent, although its effectiveness has not been well studied. It has the advantage of being considered a “natural” substance, but the few studies that have examined it have found it less effective than DMSA . It is fat-soluble and can potentially cross the skin, but this has not been tested. Its fat-solubility may (or may not) allow it to penetrate the brain tissue better, but this has also not been demonstrated.

A number of naturopathic remedies claim to remove mercury and heavy metals, but this claim is often based on the parent plant’s ability to remove mercury from the environment. As a result, these naturopathic remedies may themselves have a high degree of mercury contamination. At any rate, none of the naturopathic “chelating agents” have been tested to support their claims. In the final evaluation, only DMSA offers the combination of safety and effectiveness that would warrant its use. DMPS is a close second, limited only by higher toxicity.

Safety of chelation

Common less serious side effects of DMSA include nausea, vomiting and diarrhea. Skin rashes have also been reported—these are often erroneously referred to as “mercury rashes” and attributed to the removal of mercury. Regrettably, the same rashes are seen in people who have no mercury toxicity and are merely due to a drug reaction. A rare and unpredictable reaction (and potentially lethal, if not treated promptly) is Stevens-Johnson Syndrome, a severe drug reaction that presents with lesions on the skin and in the mouth and gastrointestinal tract.

No significant adverse drug interactions have been reported with DMSA, but most of the children who received DMSA for lead poisoning were not taking other medications—and most of this experience predates many of the medications used for autism. Increased zinc and copper excretion has been noticed in animal studies , but this is apparently easily corrected by moderate zinc supplementation. Copper supplementation is generally not needed.

The more serious side effects of DMSA are primarily bone marrow suppression and liver injury. In the thousands of children who received DMSA for lead poisoning, somewhere between 1% and 3% developed either elevated liver enzymes (a sign of liver cell injury), low white blood cell and/or platelet counts (a sign of bone marrow suppression) or both. In all cases, these abnormalities resolved after DMSA was stopped. However, these children were being monitored with frequent blood tests and received treatment for less than three months.

There is a danger that long-term use of DMSA without close monitoring could lead to irreversible bone marrow or liver damage. This has not yet been reported, but is a compelling reason to limit the duration of DMSA therapy and to have blood tests done every one to three months. The safety of DMSA—taken for less than six months—is well-established, but this safety has not been demonstrated over the long-term.

Finally, there are as many dosing schedules for DMSA as there are practitioners who make claims about it. As perhaps a ridiculous extreme, one practitioner has asserted that DMSA must be given every two to three hours around the clock! This person also insists that failure to follow this schedule will result in more mercury being deposited in the brain. Fortunately, this is absolutely wrong! Doses as infrequent as once a week have been effective at removing mercury and lead, although at a much slower rate than the recommended dosing schedule of three times a day.


[1] Is autism due to mercury?

There is no convincing data supporting a link between mercury or thimerosal and autism. This is not to say that mercury and thimerosal cannot cause autism, just that there is no data to support the connection.

[2] Mercury testing.

Mercury testing, especially if done with a mail-order lab, can be both misleading and overly expensive. If you truly suspect mercury poisoning, spend $35 for a urine mercury test at your local clinic or hospital—don’t spend up to $300 to get information of questionable accuracy and minimal utility.

[3] Chelating agents.

Many of the remedies promoted to remove mercury and other heavy metals are either not effective, not safe or both. Of the available chelating agents for mercury, DMSA offers the best safety and the best effectiveness.

[4] Safety.

Despite its impressive safety record, DMSA is not without side effects. Long-term treatment with DMSA has not been studied and may result in serious problems. Close medical monitoring is strongly recommended if you decide to use DMSA therapy on your child.


  1. Is it not also true that even in the legitimate use of chelation for lead poisoning, there is no expectation of reversing whatever neurological damage has already occurred? I would think this would be another strike against the credibility of chelation for autism. — Lisa Randall    Jul 27, 02:37 PM    #

  2. The studies that have looked at removal of lead by chelation (that Autism Diva has looked at on pubmed) showed no improvement in IQ or behavior, (or both?)

    Brain damage in general is not seen as reversible.

    Some of the autism/mercury parents think their kids got toxified while in the womb from a rhogam shot that had thimerosal in it.

    There’s no evidence for that, but besides that, they think that they can chelate the kid NOW and affect proposed damage do when the brain was developing? They obviously have no clue about brain development and probably have never looked into Fetal Alchohol Syndrome. There’s nothing that undoes that, but the kid can learn to use what he has to the best possible extent. Autism Diva    Jul 27, 02:46 PM    #

  3. Because there’s no way of knowing how much improvement in a child’s behavior and abilities is the result of natural developmental processes, the only accurate way to test chelation would be to perform double-blind studies with autistic adults.

    If you’re interested in an unscientific anecdote, I had all of my amalgam fillings removed 10 years ago and took chelation supplements for a few weeks. It was my dad’s idea; he is a major health faddist, antivax, supplements out the wazoo, toxic fumes in the woodwork, you get the idea.

    I noticed some improvement in my sense of smell after having the amalgams taken out, but the main benefit was just the nice new pretty composite fillings.

    I’m still just as autistic as ever.

    So is my dad… Bonnie Ventura    Jul 28, 08:38 AM    #

  4. Someone got all mad at Frank Klein (autistic advocate) a couple of years ago and said Frank obviously was not able to understand chelation, etc, because he, Frank, needed chelation. He made some kind of comment like someone ought to force Frank to get chelated for his own good.

    Anyway, I thought, man, if they offered to put Frank (or any of us) up in a nice hotel in a resort for a few weeks while we got chelated. Any of us would likely agree to it, and in the end we’d still be autistic but get a nice vacation out of it.

    Personally, I’d be glad to get injected with a 50 or 100 times vaccine level dose of thimerosal if it would shut these people up, the only problem is that it would have to be given in multiple shots because it’s irritating to the muscles at higher doses (the muscles don’t become autisitic, it’s not that)

    I figure I could get about the thimerosal divided in 10 or 15 hypos and poked into various muscle groups. Of course, when it was all done, the mercury phobes would say it wasn’t thimerosal, but just water because nothing will convince them at this point.

    Maybe I could get an old bottle of mercurochrome and paint it on a self-inflicted injury or something.

    I could (and would) take a bath in contact lens solution containing thimerosal. (gasp)

    Camille — Camille    Jul 28, 02:07 PM    #

  5. Dr. Laidler,

    I appreciate review of information on mercury toxicity and chelation in those diagnosed as autistic.

    As the parent of a child undergoing chelation, I read it with great interest and I had a lot of comments.

    I have posted a copy of the article with all my comments and questions on my blog:

    I am really interested in having good healthy debate on this topic, and I have not found enough good, drama free, material out there.

    I really appreciate yours. Ginger Taylor    Jul 30, 05:32 AM    #

  6. Boy, Camille certainly needs to do her homework! They removed mecurochrome for a REASON. Same with mercury in tooth powders. Ever hear of “Pink Disease”? If she thinks mercury is safe, go ahead and inject her! I’ll go ahead and file her under “Fool”. The issue is whether Autism and other neurological/developmental disorders have a link to vaccines and heavy metals… even the most skeptical scientist realizes mercury is hazardous. — Pam    Oct 15, 10:53 AM    #

  7. Very helpful, informative, and hype-free article, Dr. Laidler—thanks. But could you add a section addressing the question of developmental origin of the impairments that chelation is supposed to mitigate? In other words, to what extent is the presence of mercury compounds in the body here and now responsible for observed impairments in autistic people, and to what extent are such impairments due to developmental trajectory that took place years ago (whether or not affected by the presence of mercury compounds in the body), and therefore unlikely to be reversed by removal of mercury compounds from the body here and now?

    There are some big questions that arise in such a discussion and need to be addressed by it in one way or another. Among them:

    1. When parents chelating their autistic kids report improvement, what specific changes have occurred? Is this consistent across many autistic kids (or adults) who have received chelation? One of the truly frustrating things about Bernard Rimland’s Autism Research Institute is the lack of specificity in the data it collects about improvement due to the interventions and treatments it reports on, regarding what exactly improved or changed as a result of the intervention or treatment.

    2. Which mercury compounds (ethyl-mercury? elemental mercury? mercury-sulfur compounds?) actually accumulate in the body, and where do they accumulate? There seems to be a tremendous amount of confusion (some of it intentional) regarding this question. Seems to me that identification of specific compounds and specific points of accumulation within body subsystems is essential to any sort of understanding of how to approach the removal of those compounds safely and effectively (if, in fact, removal of them here and now actually does any good, pursuant to the main question).

    — Phil Schwarz    Mar 9, 08:38 AM    #

  8. Is there a constructive reply when faced with a physician’s refusal to conduct the test? One almost brands one’s-self a “kook” for asking. I have 4 symptoms of potential toxicity, and would like to eliminate mercury as a possibility. Why is that not a reasonable approach, from the general physician’s point of view?

    — Camden    Mar 19, 04:09 PM    #

  9. I would ask him for the reasons for his reluctance, and ask him what alternate explanations he might be able to offer for the phenomena that you describe as “symptoms of potential toxicity.” He might fundamentally object to ordering what he feels are unnecessary tests.

    Kathleen Seidel    Mar 19, 05:27 PM    #