Nature Medicine Clinic

New Patient Forms

Heavy Metals

Individually toxic, synergistically lethal

In the past 30 years, the growing concern for a reduction in environmental pollution has led to continuing research on the toxic effects of heavy metals. Mankind’s exposure to heavy metals is not new to our environment; in fact, we have repeatedly been poisoning ourselves throughout history. In the late Roman Empire, aristocrats used to drink out of lead cups and many water lines were made out of lead pipes. Several hundred years passed before a connection between mental illness and contaminated drinking water was established. The use of mercury for the treatment of acute and chronic infection was used in the 1700s. Decades passed before the neurotoxic and immunosuppressive effects of mercury were documented.

Virtually all metals can produce toxicity when ingested in sufficient quantities. Most metals have a very narrow therapeutic margin before they become neurotoxic and in some cases carcinogenic. The common heavy metals include: arsenic, lead, mercury, cadmium, aluminum, iron, copper, nickel, silver and beryllium.

Everyone is exposed to heavy metals in our environment and therefore we all have certain levels inside our bodies. The accumulation of this exposure has negative impacts on our health.

Heavy Metals and Health Effects

 Chemicals and heavy metals are ranked by the US Agency for Toxic Substances & Disease Registry (ATDSR) based on frequency, toxicity and the potential for human exposure. Only 250 substances are considered to be on the ATDSR list of 847 candidate substances.

Arsenic:  Ranked #1 on ATSDR Priority List of Hazardous Substances (2011)

  • May be exposed to arsenic in the air, drinking water and food (usually the largest source)
  • Prior to 2003, arsenic was used in the production of wood preservatives, primarily copper chromated arsenate (CCA)
  • Sawing, sanding or burning wood can generate arsenic contaminated sawdust or smoke
  • Various organic arsenicals are used as herbicides, pesticides for ants, termites and spiders and antimicrobial additives for animal and poultry feed

Health Effects

  • Inhalation of inorganic arsenic may cause respiratory irritation, nausea, skin effects and increased risk of lung cancer
  • Long term oral exposure to low levels of inorganic arsenic may cause dermal effects (such as hyperpigmentation and hyperkeratosis, corns and warts) and peripheral neuropathy characterized by a numbness in the hands and feet that may progress to a painful “pins and needles” sensation. There may also be an increased risk of skin cancer, bladder cancer and lung cancer.

 Lead: Ranked #2 on ATSDR Priority List of Hazardous Substances (2011)

  • Prior to 1991, lead was found in gasoline, paint and plumbing fixtures and therefore could easily accumulate in the body. Lead can remain in the body for a min of 30 years.
  • The most likely source of exposure is ingestion of contaminated food and drinking water
  • Exposure can also occur via inadvertent ingestion of contaminated soil/dust or lead-based paint
  • Lead can leach into drinking water from lead-soldered joints or leaded pipes
  • Some types of hair dyes and cosmetics (lipsticks) may contain lead compounds
  • Other potential sources of exposure are hobbies that use lead: fishing weights, soldering with lead solder, making stained glass, making ammunition and using firing ranges
  • Leaded gasoline is still used in some race cars, airplanes and off-road vehicles

Health Effects

  • Linked to cancer in humans
  • Systems affected:
    1. Neurological: has been shown to reduce IQ in children by minimum of  5 points
    2. Hematological (blood): decreased activity of several heme biosynthesis enzymes at blood levels (PbB) <10µg/dL
    3. Gastrointestinal: colic in children PbB 60-100µg/dL
    4. Cardiovascular: elevated blood pressure PbB<10µg/dL
    5. Kidney: Decreased glomerular filtration rate at mean PbB<20µg/dL= decreased kidney function

 Mercury:  Ranked #3 on ATSDR Priority List of Hazardous Substances (2011)

  • Mercury, which is everywhere in the environment due to constant off gassing from the earth’s crust, exposure is from: 1. Amalgams, 2. Fish, 3. Vaccines [thimerosal preservative is 50% mercury by weight], 4. Pesticides 5. Corn Sweeteners (HFCS-high fructose corn sweeteners)
  • According to Health Canada, silver (mercury) amalgams are the largest single source of mercury exposure
  • In the FDA’s Total Diet Survey, mercury was found in 100% of canned tuna samples (avg. 0.277ppm), frozen cod/haddock fillets (avg. 0.132ppm), canned mushrooms (avg. 0.0298ppm) and shrimp (avg. 0.0281ppm), fish sticks (avg. 0.0254ppm) and crisped rice cereal (avg. 0.0044ppm)
  • Nearly all fish contain trace amounts:
  • Mercury is released into the environment by oil burning, from its use as a fungicide (applied to seeds), from outdoor paint (banned in indoor paint in 1990), from processes involving chlorine manufacture and by cremations (a single crematorium estimates the release of more than 5,400 kg of mercury per yr.)
  • The U.S. Environment Protection Agency states a maximum ingestion of 5.5 μg/day of mercury for the average American woman of childbearing age. Interestingly, a can of cola has 39 g of HFCS which could contain as much as 22.23 μg of mercury.

Health Effects

  • Mercury is rapidly absorbed and accumulates in several tissues, leading to increased oxidative damage, mitochondrial dysfunction and cell death
  • Affects neurological tissue (demyelinates nerve fibers), kidneys and the immune system
  • Crosses both the Blood Brain Barrier and the placental barrier, present in breast milk
  • Affects neurotransmitters dopamine, serotonin and norepinephrine
  • Can remain in the body for decades unless removed
  • Mercury toxicity can result in:
    1. speech impairment, hearing impairment and sensory disturbances
    2. hand  and leg tremors, dizziness, loss of pain sensation, cramping, insomnia
    3. tinnitus, loss of touch sensation, muscular weakness, decreased memory
  • Implicated in Alzheimer’s disease and other chronic neurological complaints, possible carcinogen

 Cadmium: Ranked #7 on ATSDR Priority List of Hazardous Substances (2011)

  • Cadmium is part of the soil and in every form of rock in the environment
  • May be exposed to cadmium in drinking water, food and tobacco
    • Low levels are found in all foods, highest levels are found in shellfish and organ meats
    • Found in brilliant paints i.e. cadmium yellow, cadmium red and cadmium orange

Health Effects

  • Can severely damage the lungs and is a carcinogen to humans
  • Eating food or drinking water with very high levels severely irritates the stomach, leading to vomiting and diarrhea
  • Long-term exposure to lower levels of cadmium in air, food, or water leads to a buildup of cadmium in the kidneys and possibly kidney disease. Other long-term effects can include fragile bones and decreased bone density.

Sources of Heavy Metals:

Heavy metals are a concern for the entire population; we are all exposed to heavy metals daily. In Toronto, the lead pipe replacement program that began in 2010 was later abandoned due to the increased danger of lead in the drinking water. Originally, the city planned to replace the pipe from the street up to the property line, giving homeowners the option to replace the remaining pipe. An environmental engineer provided strong evidence that the joining of the new copper pipes to existing lead pipe, can cause the rusting lead to fall off into the water system.

Water is not the only source of heavy metal contamination. Environmental Defense tested the makeup bags of 6 Canadian women in 2010. The items included foundations, concealers, bronzers, powders, blushes, mascaras, eye liners, eye shadows, lipsticks and glosses.  Arsenic was detected in 20%, cadmium in 8% and lead in 96%. Interestingly, the highest levels were found in lip glosses, something that can easily be ingested.

Environmental Defense also conducted research on heavy metals in the Canadian diet. The Total Diet Study and the Metallic Lunch Study indicated alarming amounts of cadmium and lead in food. High levels of mercury can also be found in high fructose corn syrup (HFCS).

Synergistic Effects of Heavy Metals

The synergistic effect of mercury, cadmium and lead is unfortunately just now being investigated and we do know that their effects are more than simply additive. In other words, one plus one does not equal two. One plus one may make 1,000.

Separately, mercury and lead are extremely neurotoxic but combined the negative effects are worsened. An animal study investigated the collective outcome of mercury and lead administration to rodents. A dose of mercury sufficient to kill 1% of tested rats, when combined with a dose of lead sufficient to kill less than 1% of rats, resulted in killing 100% of the tested rats.

Similar observations are presented in the following chart with aluminum and mercury on nerve cell (neuron) survival. Individually, the neurotoxicity of aluminum revealed a 15% death rate of neurons after 24 hours and mercury a death rate of 70% after 24 hours. When combined, the metals synergistically resulted in a significant death rate of 95% of neurons after 24 hours. Interestingly, aluminum and mercury are used in childhood vaccinations (please refer to Vaccines for more information).

pastedGraphic.pngThis suggests that many people are absorbing dangerous levels of metals. The CDC and Health Canada continue to monitor the exposure of the population to environmental chemicals. For more information please refer to: The CDC Fourth National Report on Human Exposure to Environmental Chemicals or The Canadian Health Measures Survey getSurvey&SDDS=5071&Item_Id=129548&lang=en.

The accumulation of heavy metals in the body can have serious health effects. Fortunately, there are treatments, including DMSA, DMPS, EDTA and Therapeutic Fasting that have been used to effectively reduce the burden of heavy metals.


  7. Metallic Lunch: an analysis of Heavy metals in the Canadian diet. Environmental Defense Canada, May 2003.
  8. Wallinga, D. Institute for Agriculture & Trade Policy. Not So Sweet: Missing Mercury and High Fructose Corn Syrup. 2009.
  9. Shubert et al., Combined Effects in Toxicology-A Rapid systematic Testing Procedure: Cadmium, Mercury & Lead. J. of Toxicology & Environmental Health 4:763, 1978.
  10.   Hayley, B. Mercury toxicity: Genetic susceptibility and synergistic effects. Medical Veritas. 2 (2005) 535–542.