Chapter 8
Heavy Metals Toxicity
By Dr. William Shaw

 Heavy Metals, Especially Mercury, Implicated in Autism and Learning Disabilities

There has been a marked interest in the role of toxic metals in autism and PDD. The potential role of mercury was of special concern because of evidence that the amount of mercury injected into infants and toddlers via childhood vaccinations has exceeded government safety guidelines on both individual and cumulative vaccine doses. Vaccines contain the preservative thimerosal, which is 50% ethyl mercury. Symptoms of mercury poisoning are very similar to those of autism and include stereotypical behaviors, delayed speech, sensory abnormalities, toe walking, self-injurious behaviors, gastrointestinal abnormalities, and cognitive impairments.

 What is Mercury?

Mercury is a naturally occurring metal found throughout the environment. Mercury can enter the environment from deposits of ore containing mercury due to wind or rain or from the actions of humans. In addition to mercury from vaccines, other major sources of mercury that contaminate humans are dental fillings, which are about 50% mercury and large fish such as tuna and swordfish. Mercury exists in two major forms, inorganic and organic. Inorganic mercury consists of metallic mercury and inorganic mercury compounds called salts. Metallic mercury is a liquid at room temperature. It is the shiny silver material in thermometers and is commonly combined with silver as an alloy for dental fillings. Mercury is also used in alkaline batteries. Liquid mercury from thermometers can give off vapor if a thermometer breaks which could then be absorbed through the lungs. Organic mercury compounds include methylmercury, ethylmercury, and phenylmercury. Methylmercury is produced from inorganic mercury by microorganisms in the environment and perhaps by the microorganisms in the intestinal tract. Methylmercury is extremely toxic. Exposure to three drops of methylmercury to the gloved hands of a researcher was fatal. Parents of a child with developmental delays and a muscle disorder reported that their child ate salmon or tuna five or six times a week and was found to have high levels of mercury in the hair and blood. Although fish are an excellent source of essential fatty acids, most large fish have significant amounts of methylmercury and the FDA has recommended that women abstain from certain fish during pregnancy. Since methylmercury is fat soluble, it might also contaminate supplements derived from fish oils.  In addition, mercury was used as an antifungal agent in paint prior to 1992. Therefore, anyone in an older house needs to be aware that peeling paint or sanding off existing paint could lead to mercury exposure. Mercury in the fillings of pregnant women may be a significant source of exposure to developing infants in utero. Ethyl mercury is the most common preservative found in vaccines, nasal sprays, and eye ointments, and up until ten years ago, has been the preservative agent in contact lens solutions.

 Health Effects of Mercury and Recurrent Candida

Mercury is toxic to all tissues and organs. Documented toxicity includes significant effects of mercury on the lungs, heart, gastrointestinal symptoms, blood, muscles, liver, kidneys, skin, thyroid gland, immune system, nerves, and brain. Dental workers exposed to mercury had significantly more reproductive failure than controls including increased abortions, stillbirths, congenital malformations, and menstrual disorders; the extent of abnormalities correlated with mercury levels in the hair. A wide variety of neurological abnormalities are associated with mercury toxicity including muscle tremors, irritability, excessive shyness, nervousness, insomnia, hearing loss, hallucinations, headaches, memory loss, visual field defects, hostility, depression, anxiety, unsteady walking, decreased hand-eye coordination, abnormal reflexes, EEG changes, decreases in intelligence and memory tests, increased aggression, weakness, muscle cramps, and tingling of the hands and feet. The half-life of mercury in the body ranges from 40-80 days. The recurrent Candidiasis that is common in autism may be linked to mercury and/or lead exposure in some cases. Workers exposed to even “safe” levels of mercury were found to have white blood cells with impaired ability to kill Candida. The reason is that mercury and lead inhibit the key white blood cell enzyme myeloperoxidase, an enzyme that produces hypochlorite ion, which is the body’s main defense against Candida.

 Other Heavy Metals

Heavy metals may often have combined effects so that exposure to multiple heavy metals at low levels might be just as toxic as exposure to one metal at a high level. Heavy metals found to be elevated in children and adults with autism and PDD include uranium, mercury, cadmium, arsenic, lead, aluminum, and antimony. Many children with autism and PDD have multiple toxic elements in hair or in urine after DMSA challenge.  Arsenic is high in seafood such as shrimp and crabs, chicken feed as an additive, pressure treated wood (used in playground equipment and decks), and may be elevated in drinking water. Lead is found in paint in older houses and in soils near freeways exposed to leaded gasoline in the past. Antimony is found in some of the flame-retardants in children’s pajamas and in carpet. Aluminum is common in cookware, baking powder, drinking water, and cans.  Cadmium is high in cigarette smoke and may also be released from particles of steel belted tires. Uranium may occur naturally in rock or may enter the environment as a contaminant from the arms industry, which uses uranium in bullets and shells because of its extreme hardness.  (All forms of uranium are radioactive.)

 Treatments of Mercury Toxicity

Chelation therapy is the preferred method for removal of mercury and many other heavy metals. Chelation agents bind to heavy metals in the blood or tissues. Then the metal-chelation agent complexes are eliminated in the urine or stool.  Chelation agents which are prescription drugs include British Anti-Lewisite (BAL), D-penicillamine, dimercaptopropane-1-sulfonate (DMPS), ethylenediamine tetraacetic acid (EDTA) and CHEMET, a trade name for 2,3-dimercaptosuccinic acid (DMSA). DMSA appears to be the most effective agent of the group with the fewest side effects. Nutritional supplements that may aid in mercury elimination and/or reduce toxic effects include N-acetylcysteine, selenium, lipoic acid, vitamin E, cilantro, vitamin C, milk thistle, glycine, garlic, and peptidyl clathorating products, among others. In addition, mercury and other heavy metals may be removed by sauna treatment, which increases the excretion of mercury in the sweat.

 How to Decide Which Test is Most Appropriate for Metals Testing

Hair Analysis is considered by many to be the best, the easiest, and the most cost-effective way to screen for heavy metal toxicity.  Heavy metals, such as mercury, may be 250 times higher in the hair than in the blood.  It is important to note that mercury toxicity will only show up in the hair if the exposure has been recent.

Some individuals consider a DMSA (Chemet) challenge test to be an even more sensitive screen for metal toxicity than hair because the drug DMSA is able to bind heavy metals deposited in tissues in the body whereas such metals might not be detected by hair tests. (This is true with mercury, when the exposure has not been recent.) The difficulties associated with urine DMSA testing are:

  • First, DMSA is a drug that must be prescribed by a physician. However, some nutritional supplement companies may also sell it as a nutritional supplement.
  • Some physicians may be reluctant to prescribe it unless they have used DMSA previously.
  • Second, numerous side effects can be caused by DMSA. Although the short exposure of the person being tested by DMSA is unlikely to cause significant long-term side effects, such side effects are still possible.

Urine metal testing without DMSA is generally considered less sensitive than hair metal testing or urine metal testing with a DMSA “challenge.” Since the metal issue may be very important, a person might want to get both a baseline and a post-challenge urine test done.

If the patient goes on DMSA therapy because of abnormal metal results, the patient should get a weekly complete blood count with white cell differential and platelet estimation.  Many physicians, who follow a slower chelation protocol, prescribing lower doses spread over a longer period of time, recommend blood testing only every 2-3 months.

Blood testing is considered the least sensitive but most significant indicator of toxicity of metals. Low metal levels in blood do not rule out metal toxicity. High metal values in blood almost always indicate a clinically significant and often recent toxic exposure.

 Side Effects of DMSA

The Physicians Desk Reference lists a number of side effects associated with DMSA usage. The side effects affect between 1-20% of the individuals. It might be expected that a single dose of DMSA would cause fewer side effects than a long-term treatment with DMSA. Common side effects include:

  • Gastrointestinal side effects include nausea, vomiting, stomach pain, and abdominal pain and diarrhea. 
  • Hematological (blood) side effects include neutropenia, eosinophilia, and increased platelets.
  • Temporary regression of autistic symptoms as the metals are being “stirred up.”
  • Elevated liver enzymes and other side effects including drowsiness, dizziness, sleepiness, rash, decreased urination, cardiac arrhythmia, leg and knee pain, and flu-like symptoms.

 Treatment for Heavy Metal Toxicity

If the challenge test or hair analysis shows toxicity, then a treatment plan needs to be implemented. The most important aspect of the treatment plan is the removal of any current source of heavy metal poisoning. If the child’s house is contaminated with lead or mercury-based paint, the parents may have to move or have the lead removed from the house. If the child is chewing on pajamas containing antimony-containing flame-retardant, they may have to be replaced. If the child has significant mercury from vaccines containing the mercury compound thimerosal, non-mercury vaccines should be used in the future. Fish intake may have to be eliminated or reduced. If the water supply is high in uranium or arsenic, then bottled distilled, deionized, or reverse osmosis water should be used.

 DMSA Treatment

The next step is the use of agents to remove toxic metals. The most commonly used agent is DMSA. Despite some side-effects, DMSA is considered the safest agent and is available without a prescription. Supplementation with beneficial minerals such as calcium, magnesium, selenium and zinc is very important since these minerals may compete with toxic metals being depleted during the chelation process. DMSA is effective in removing many heavy metals such as lead, mercury, cadmium, arsenic, and antimony but is not effective in the removal of aluminum.  Chelation can take from 1 – 2 years, with younger children successfully chelating more quickly.  In addition, certain nutritional supplements have also been used for the removal of heavy metals although safety and efficacy studies frequently are lacking.  As with all treatments, it is advised to always proceed cautiously, do your research, and engage the help of a qualified and experienced physician.

 Lipoic Acid

The vitamin lipoic acid (also referred to as alpha lipoic acid or ALA) has two sulfhydryl groups that readily bind to mercury and result in its elimination. However, concerns have been raised that lipoic acid might also transfer heavy metals from the peripheral tissues to the brain so it might be wise to limit lipoic acid until DMSA chelation has been completed and the bulk of toxic metals have been removed. Lipoic acid is available in any health food store.

 Tests Available From The Great Plains Laboratory

  • All tests are performed using ICP-mass spectrometry, the most advanced analytical method available
  • Hair, blood, and urine tests are all available. Hair testing is prohibited in New York State probably because of excessive claims of promoters of such testing in claiming uses beyond determination of exposure to heavy metals. 


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