• An Exchange of Views
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• Foreordained Conclusions
• Reflections on the Hidden Horde
• A Little Clarification
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• Time for RFK Jr. to Come Clean
• Autism Lupron: Playing With Fire
• One for the Times
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meow meow meow... blah blah blah
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Ethics of Vaccines, Center for Bioethics, U Penn
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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.
by James R. Laidler, M.D.
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) toxicityif 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 countriesCanada and Denmarkhad removed thimerosal from their vaccines in the 1990s (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 1990s. This study was greeted by howls of outrage from some that advocated the connection between thimerosal/mercury and autismthe 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 childrenor autistic children of relatives and friendsto VAERS as injuries from thimerosal-containing vaccines. This has irrevocably tainted the VAERS database with duplicate and spurious reports.
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 poisoningif the testing is valid. While laboratory accuracyand costis 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 usethere 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 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 orallyit 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 USprimarily for lead poisoningand 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 doesnt 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 wont be absorbed through intact skin. It is interesting to note that none of the individuals or corporations selling this preparation hasto my knowledgeperformed 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 acida sulfur-containing fatty acidhas 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 plants 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.
Common less serious side effects of DMSA include nausea, vomiting and diarrhea. Skin rashes have also been reportedthese 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 medicationsand 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 DMSAtaken for less than six monthsis 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.
 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.
 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 hospitaldont spend up to $300 to get information of questionable accuracy and minimal utility.
 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.
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.