Heavy Metal Toxicity (Overview)

By Cat, April 2022 (originally from old iWeb site, July-Aug 2007)

What’s a Heavy Metal?

No, I don’t mean a type of rock music!

Heavy metals are a class of minerals with a high molecular weight, and typically fall in the middle section of a periodic table. Some are essential (up to certain levels) for specific enzymatic activity in our bodies, such as copper, zinc, selenium and iron, but can be toxic above trace levels. Some require proper balance, such as zinc and copper require a balance of 15:8 (zinc-to-copper).

Iron is toxic in the blood if not bound by hemoglobin.  Other heavy metals, the so called toxic heavy metals, (such as aluminum, arsenic, cadmium, lead, mercury, and radium) are toxic at any level.

Read on for more.

Why Are They Toxic (some above certain levels, others at all levels)? 

Heavy metals readily bind to oxygen, nitrogen and sulfur, all of which are present in abundance in the human body in general, and particularly in proteins.  When a heavy metal binds to one of these metals in a protein molecule, it alters, or completely disables, that protein from doing its normal function. 

Proteins are the workhorses of the body.  Not only are they abundant in muscles, allowing them to do their action, but also they are present in virtually every organ and tissue in the body.  The powerful enzymes, which perform vital, life-giving and life-protecting functions, are made of protein. In fact, it is the binding of heavy metals to proteins and particularly to enzymes, that causes much of the damage, from the brain to the kidneys.

Many proteins bind specific essential minerals, such as zinc, copper, iron, manganese.  For example:

  • Haemoglobin contains iron, and would not be able to carry oxygen in the blood if iron were not present.  
  • Many enzymes responsible for DNA and RNA synthesis contain zinc.

But when an enzyme binds a toxic metal, its ability to do its normal function is altered or stopped altogether.  As the exposure of the body to these harmful metals increases, the damage increases.  But it may not be noticed for years after the exposure, as the effects are slowly cumulative.

Some Mimic Healthy Minerals

Another way in which heavy metals do damage is by mimicking essential minerals.  For example, lead easily mimics calcium and zinc, and is incorporated into bone tissue.  There it can hide for decades, meanwhile weakening the bone.

Toxicity of Specific Heavy Metals

Lead Toxicity

See also Wikipedia on Lead Poisoning (5a).

Lead has the ability to mimic other biologically important metals, such as calcium, iron and zinc.  Lead binds to and interacts with the same proteins, enzymes and other biochemical molecules as the other metals, but then causes them to function differently or inhibiting their action.  For example, lead accumulates in bone, in place of calcium, where it may be stored for years, and all the while weakening the structure of bone.  When bone turnover occurs, the lead can be released causing acute symptoms of lead poisoning. (5,6)

The symptoms of chronic lead poisoning include neurological problems, such as reduced cognitive abilities, or nausea (5b), abdominal pain (5c), irritability (5d), insomnia (5e), metal taste in oral cavity, excess lethargy (5f), or hyperactivity (5g), headache (5h) and, in extreme cases, seizure (5i) and coma(5j). There are also associated gastrointestinal problems, such as constipation (5k), diarrhea (5l), vomiting (5m), poor appetite (5n), weight loss (50), which are common in acute poisoning. Other associated effects are anemia (5p), kidney problems, and reproductive problems.

In humans, lead toxicity sometimes causes the formation of a bluish line along the gums (5q), which is known as the “Burton’s line”, although this is very uncommon in young children. Blood film (5r) examination may reveal “basophilic stippling” of red blood cells, as well as the changes normally associated with iron deficiency anemia (microcytosis and hypochromia).

A direct link between early lead exposure and extreme learning disability (5s) has been confirmed by multiple researchers and child advocacy (5t) groups.

A July 2007 study directly links lead exposure to violent crime rates in the U.S. and other countries.[10]

Signs and Symptoms (General)

Lead poisoning may be hard to detect at first, because children who appear healthy can have high levels of lead in their bodies. The accumulation of lead usually is gradual, building up unnoticed until levels become dangerous and cause signs and symptoms. See Mayo Clinic (9).

Signs and Symptoms in Children

The signs and symptoms of lead poisoning in children are nonspecific and may include (see Mayo Clinic (9)):

  • Irritability
  • Loss of appetite
  • Weight loss
  • Sluggishness
  • Abdominal pain
  • Vomiting
  • Constipation
  • Unusual paleness (pallor) from anemia
  • Learning difficulties

Signs and Symptoms in Adults

Although children are primarily at risk, lead poisoning is also dangerous to adults. Signs and symptoms of lead poisoning in adults may include (see Mayo Clinic (9)):

  • Pain, numbness or tingling of the extremities
  • Muscular weakness
  • Headache
  • Abdominal pain
  • Memory loss
  • Mood disorders
  • Reduced sperm count, abnormal sperm

Aluminum Toxicity

How aluminum can harm your brain (and it’s used in vaccines) – see Mercola (1c)  

I’d like to expand on this topic, especially if Mercola’s article is no longer available

Arsenic Toxicity

from Online Lawyer Source.com (10):

symptoms:  physical symptoms: if ingested- stomach and intestinal irritation, nausea, vomiting, diarrhea, fatigue, heart arrhythmia, blood vessel damage, impaired nerve function, skin pattern changes, and the development of liver, bladder, kidney, prostate, and lung cancer; and if inhaled- irritated throat and lungs, skin changes, circulatory problems, and nervous system disorders.

from Dartmouth.edu article (11 – no longer valid); try (11a)

Studies in areas with high levels of drinking water arsenic, such as Taiwan, Argentina and Bangladesh have shown that chronic exposure to arsenic, even at levels that are not associated with clinical signs of arsenic poisoning, is associated with a greatly increased risk of vascular and heart disease, diabetes, reproductive and developmental problems, and a wide variety of cancers including skin cancer, bladder cancer, lung cancer, liver cancer and kidney cancer.

How arsenic exposure is able to affect the risk of so many different diseases is not well understood. Research led by Joshua Hamilton is examining a specific mechanism that Hamilton and colleagues believe is one of the primary ways that arsenic affects human health. Their laboratory discovered that arsenic can act as a potent endocrine disrupting chemical (EDC). Previously, most work on EDCs focused on pesticides and other organic chemicals in the environment that mimic hormones. However, Hamilton and colleagues demonstrated that arsenic can also affect hormone processes, but by a unique mechanism that does not involve hormone mimicry. The primary goal of the research is to understand this mechanism of action at a more detailed level, and to investigate the health consequences of such hormone disruption.

Hormone Receptors as Targets for Arsenic

Hamilton’s laboratory had previously demonstrated that extremely low levels of arsenic could alter hormone-mediated pathways in the cell. Arsenic was first shown to disrupt the ability of a particular receptor, the glucocorticoid hormone receptor, to regulate expression of genes that are normally responsive to glucocorticoid hormone. Glucocorticoids control many different functions in the body, including the blood sugar, glucose (after which they are named), cell growth and differentiation, inflammation (which is what topical cortisol is used for), embryonic and fetal development, and many other functions. So it would not be surprising that disruption of this key hormone pathway might affect a wide variety of diseases including cancer, diabetes, heart disease, and development.

Hamilton’s group then went on to show that arsenic has similar effects on all five steroid receptor pathways. These pathways include not only the receptors for glucocorticoids but also those for the sex steroids, estrogen, progesterone, and testosterone, as well as the receptor for mineralocorticoids (aldosterone, which controls salt concentrations and other kidney functions). Through findings in more recent studies, Hamilton’s laboratory has extended this list of affected pathways to include the receptors for retinoic acid and thyroid hormone, which are part of the same large family of nuclear hormone receptors. Collectively, these hormone receptor regulated pathways control a myriad of body functions, and so disruption of all of these by arsenic would be expected to have profound consequences on disease risk. One of the principal aims of the current work is focused on how arsenic is able to disrupt all of these pathways, examining these processes at the molecular level inside cells.

(read rest of the above article for more)

Heavy Metals and Alzheimer’s

Mercola posted an article about excess iron being a problem with Alzheimers (1d) in rats; reducing iron improved the condition. He also mentions other metals implicated in brain problems: aluminum, iron, zinc and copper.

The article (1d) includes suggestions on common sources of iron:

“Cooking in iron pots or pans. Cooking acidic foods in these types of pots or pans will cause even higher levels of iron absorption.

Eating processed food products like cereals and white breads that are “fortified’ with iron. The iron they use in these products is inorganic iron not much different than rust and it is far more dangerous than the iron in meat.

Drinking well water that is high in iron. The key here is to make sure you have some type of iron precipitator and/or a reverse osmosis water filter.

Taking multiple vitamins and mineral supplements, as both of these frequently have iron in them.”

Article (1d) also includes reducing iron if levels are found to be high from a blood test: 

“Some people advise using iron chelators like phytic acid or IP6, but I don’t think that is a wise approach as donating your blood is a far safer and more effective and inexpensive approach for this problem. If, for some reason, a blood donor center is unable to accept your blood for donation you can obtain a prescription for therapeutic phlebotomy. At the same time, you will want to be sure to avoid consuming excess iron in the form of supplements, in your drinking water (well water), from iron cookware, or in fortified processed foods.

Certain phenolic-rich herbs and spices can reduce iron absorption, such as green tea and rosemary.

Curcumin actually acts as an iron chelator, and in mice studies, diets supplemented with this spice extract exhibited a decline in levels of ferritin in the liver.

Lastly, astaxanthin, which has been researched to have over 100 potential health benefits, has been shown to reduce iron-induced oxidative damage. (1b)

Keep in mind, however, that iron is only one problematic metal for your brain. Others, including zinc, aluminum and copper (1e), are also known to accumulate in your brain and are similarly linked to Alzheimer’s disease.”


  1. Mercola (note these articles may have been removed from his site)
    1. mercola.com/2003/dec/27/toxic_metals.htm
    2. articles.mercola.com/sites/articles/archive/2012/07/19/excess-iron-leads-to-alzheimers.aspx (formerly reference (8)); no longer valid 
    3. articles.mercola.com/sites/articles/archive/2009/01/27/mercury-in-vaccines-was-replaced-with-something-even-more-toxic.aspx
    4. articles.mercola.com/sites/articles/archive/2012/07/19/excess-iron-leads-to-alzheimers.aspx
    5. articles.mercola.com/sites/articles/archive/2010/02/11/copper-pipes-in-your-home-may-cause-heart-disease-and-alzheimers.aspx
  2.  hbci.com/~wenonah/hydro/hg.htm#problem
  3. emedicine.com/EMERG/topic813.htm
  4. karlloren.com/ultrasound/p18.htm
  5. Wikipedia:
    1. en.wikipedia.org/wiki/Lead_poisoning;
    2. nausea,
    3. abdominal pain,
    4. irritability,
    5. insomnia,
    6. lethargy or
    7. hyperactivity,
    8. headache,
    9. seizure,
    10. coma,
    11. constipation,
    12. diarrhea,
    13. vomiting,
    14. poor appetite,
    15. weight loss,
    16. anemia,
    17. gums
    18. blood film
    19. learning disability 
    20. child advocacy 
  6. eje-online.org/cgi/content/abstract/138/2/185
  7. jigsawhealth.com/articles/heavy_metal_toxicity.html
  8. not used
  9. mayoclinic.com/health/lead-poisoning/FL00068/DSECTION=2: < link is no longer valid; try mayoclinic.org/diseases-conditions/lead-poisoning/diagnosis-treatment/drc-20354723
  10. onlinelawyersource.com/arsenic/sources.html Site no longer valid. Try:
    1. Arsenic Poisoning Attorneys – LegalMatch Law Library
    2. Suffered Arsenic Exposure? Seek Legal Help Today
  11. sites.dartmouth.edu/toxmetal/

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