Detox Learning Center

Back to the Basics: Heavy Metals, What Are They and Why Do They Matter?

Heavy Metals in the Headlines ― All Hype or Cause for Concern?

Heavy metals have been in the headlines a lot over the past decade.

We’ve heard about mercury and aluminum in immunizations, mercury in fish and seafood, lead in Flint Michigan’s city water supply, arsenic in apple juice and even cadmium, arsenic and lead in baby foods, rice, and cereals.

With all the bad press swirling around in both the mainstream media and the health field, it can be easy to get overwhelmed with information (and even a little paranoid).

But, before we ban all apple juices, cereals, fish, or seafood from our homes, it’s worth getting back to basics and asking the following questions:

  • What are heavy metals?
  • Are they really toxins or naturally-occurring elements in our environment? After all, heavy metals are listed in the Periodic Chart we studied in high school biology and chemistry— so doesn’t that make them naturally- occurring environmental substances?
  • And, if they do occur naturally, why aren’t they safe? What makes them become the toxic heavy metals we hear about in the news?
  • Why does it matter if they are in our water, food, and air?

Knowledge is power when it comes to protecting your health. Arm yourself with knowledge, and then you can control your health by acting and living with this knowledge. So let’s get started by answering the most basic question:

What Are Heavy Metals?

Heavy metals are generally defined as metals with relatively high densities, (greater than 4.5 g/cm) atomic weights, or atomic numbers. (1)

All heavy metals occur naturally in our environment in rocks, animals, plants, water, and soils as trace elements.

Like vitamins, minerals, and amino acids, heavy metals are typically separated into two categories:

  1.      Essential
  2.      Non-essential

Essential heavy metals are involved in critical physiological processes and considered essential, in trace amounts, to maintain various biochemical and physiological functions in living organisms.

Essential heavy metals include: (2)

  • Iron (Fe)
  • Zinc (Zn)
  • Copper (Cu)
  • Manganese (Mn)
  • Cobalt (Co)
  • And Tin (Sn)

Trace elements are chemical nutrients, which are required in small amounts by animals to perform vital roles in maintaining the integrity of various physiological and metabolic processes.

If you’ve ever taken a liquid ionic mineral supplement sourced from salt water, for example, it likely contained several naturally-occurring trace elements.

So, yes! We do need a certain amount of "essential" heavy metals in our diets to remain healthy. (3)

Now, let’s look at the "non-essential" heavy metals (the “bad guys” if you will).

Non-essential heavy metals are heavy metals not used (or needed) by the human body in normal physiological functions.

Non-essential heavy metals include: (2)

  • Cadmium (Cd)
  • Chromium (Cr)
  • Lead (Pb)
  • Arsenic (As)
  • Mercury (Hg)

These heavy metals also appear naturally in our environment in small amounts.

They are released into our environment by wind, rain other environmental activities such as volcanic eruptions.

By-products from industrial production, such as steel manufacturing and mining, and certain synthetic pesticides, fertilizers, rodenticides, and fungicides used in agriculture also release heavy metals into the environment.

It is the industrial release of these heavy metals into the environment that has increased their amounts to toxic levels in some areas.

Heavy Metals Essential vs Non-essential

All heavy metals can be found in two forms:

  1.   Organic (naturally-occurring)
  2.   Inorganic (created by chemical processes)

Typically, in their organic form, most "essential" heavy metals are harmless to humans in trace amounts. The "non-essential, inorganic" forms, however, are generally toxic even in small quantities, hence the issues we have with heavy metal toxicity today.

At the cellular level, however, "non-essential, organic" heavy metals, when introduced through high energy carbon compounds can play an essential role in balancing heavy metal levels in the body and can aid in detoxification. More to come on this in another article.

What Makes a Heavy Metal Toxic?

A toxic heavy metal is a heavy metal that is potentially toxic to humans at a certain level.

Heavy metals become heavy metal toxins when they exceed certain threshold amounts in the human body and cause disease.

Heavy metals can enter the body through polluted air we breathe, contaminated food we eat (this can come from the air, rain, or soil), or contaminated water we drink.

Once consumed or absorbed, heavy metal toxins are distributed to tissues and organs via the digestive tract and blood circulation. Since large amounts of heavy metals are distributed in the skeleton, heavy metal toxins are stored the longest in bones. (2)

Chromium (Cr), arsenic, (As) cadmium (Cd), mercury (Hg), and lead (Pb) have the highest potential to create toxicity in the human body because of their widespread use in our environment.

And, because of their high degree of toxicity, these heavy metals are of the most significant public health concern. (4)

How do these “Frightening Five” heavy metals create such havoc in the human body?

These heavy metal toxins have a strong affinity to bond with sulfur, and in the human body, they usually bind to enzymes responsible for controlling the speed of metabolic reactions; such as digestion, respiration, and detoxification.

The resulting sulfur-metal bonds inhibit the proper functioning of the enzymes involved, resulting in heavy metal toxicity in the human body.

What exactly does this mean in health consequences?

Let’s look at a few examples (of which there are many):

  • In high doses and repeated exposure, chromium and arsenic are carcinogens.
  • Cadmium can cause a degenerative bone disease.
  • And mercury and lead can damage the central nervous system and affect cognitive development and function. (5)  

Protect Yourself by Knowing Your Heavy Metals

The first step to protecting yourself against heavy metal toxicity is to know your heavy metals.

You already understand the difference between essential and non-essential, organic and inorganic, and what makes a heavy metal a heavy metal toxin, so now we’ll dive a little deeper.

The chart below lists the most common heavy metals, explains what they are, how we are exposed to them, where these heavy metals are stored in the body, and how long they stay in our bodies.

Most Common Heavy Metals:

What is it and where is it found?

It is a naturally-occurring element that is widely distributed in the Earth’s crust. It is found in water, air, food, and soil.

There are two general forms of arsenic—organic and inorganic. Organic arsenic occurs naturally, contains carbon, and occurs in living organisms like plants and animals.

Inorganic arsenic does not occur naturally, does not contain carbon, and is considered a toxic heavy metal. (6)

Forms/Uses of/Exposure to

Organic arsenic is mostly found in fish and shellfish. It is also found in water.

Inorganic arsenic compounds are found in soils, sediments, and groundwater. These compounds occur either naturally or as a result of mining and industrial use of arsenic. (6)

How used by the body/Where stored in the body

The body does not use it.

Arsenic is mostly stored in hair, nails, and skin. 

It remains in the body for about 48 hours. (7)



What is it and where is it found?

It is a silvery white metal that occurs naturally in zinc ores.

It is widely distributed in the earth’s crust.

Forms/Uses of/Exposure to

Cadmium is used in many products, including batteries, pigments, metal coatings, and plastics, and it is found in cigarette smoke.

How used by the body/Where stored in the body

Cadmium is present in trace amounts in certain foods such as leafy vegetables, potatoes, grains, and seeds, liver and kidney, and crustaceans and mollusks. (8)

It is stored in the kidney and liver.

Studies have shown that it can stay in the kidneys for up to 20-30 years. (9)

Essential/Non- Essential


What is it and where is it found?

It is a naturally-occurring element found in rocks, animals, plants, soil, and volcanic dust and gases.

Forms/Uses of/Exposure to

It comes in several different forms, including trivalent chromium (commonly referred to as chromium III) and hexavalent chromium (referred to as chromium IV).

Chromium IV is the inorganic form created through industrial processes and considered a heavy metal toxin. It is widely used in electroplating, stainless steel production, leather tanning, textile manufacturing, and wood preservation industry. (10)

How used by the body/Where stored in the body

Chromium III is an essential nutrient for the body.

It helps the body to regulate insulin. It can be found in meats, vegetables, fruit, and grains.

It is stored in the liver, spleen, soft tissue, and bone. (11) It can stay in the body for up to a week. (12)

Essential/Non- Essential

Essential and Non-Essential

What is it and where is it found?

It is a silvery-white magnetic metal. 

It is found in ores like copper and nickel.

Forms/Uses of/Exposure to

It is essential to mammals in the form of cobalamin (vitamin B12). (13)

It is mixed with other metals to make materials turn the color blue.

How used by the body/Where stored in the body

Cobalt is a key component of vitamin B12 and is required for the synthesis of hemoglobin.

Good food sources of cobalt include fish, nuts, leafy green vegetables, such as broccoli and spinach, and cereals, including oats. (13)

It is typically stored in the liver in the human body. In general, our body uses what it needs and excretes the leftover.

Essential/Non- Essential


What is it and where is it found?

It is a reddish metal. It is found in igneous and volcanic rock.

It is also found in the food we eat and the water we drink in trace amounts.

Forms/Uses of/Exposure to

Copper is essential in the creation and health of red blood cells.

It is mined and used as a conductor of heat and electricity in the form of copper wire and mixed with tin to create bronze.

It is also used in the minting of pennies.

How used by the body/Where stored in the body

Can be found in shellfish (oysters and crabs), legumes, leafy green vegetables, and nuts.

Copper is stored in the liver. In general, our body uses what it needs and excretes the leftover.

It typically stays in the body for about 12 hours. (14)

Essential/Non- Essential


What is it and where is it found?

Iron is a strong, hard magnetic silvery-grey metal.

It is used by the human body for essential biological functions and used to create industrial materials.

Forms/Uses of/Exposure to

Iron is used by blood cells to transport oxygen throughout the body.

It is extracted from ore to create steel, cast iron, and other construction materials

How used by the body/Where stored in the body

It is in foods we eat such as liver, leafy greens, and black beans. 

It is stored in the blood, bone marrow liver, and spleen. The body uses what it needs to maintain cell and muscular health.

What is not needed is excreted on a daily basis. (15)

Too little iron can lead to a condition called anemia. Too much iron stored in the body can cause severe damage at the cellular level.

Essential/Non- Essential


What is it and where is it found?

It is a naturally-occurring bluish-gray metal present in small amounts in the earth’s crust.

Forms/Uses of/Exposure to

People are exposed to lead mainly by inhaling lead-contaminated dust particles or aerosols and eating lead-contaminated food, water, and paints.

How used by the body/Where stored in the body

When lead is ingested, it accumulates in soft tissues and bones and is stored in the fatty tissues and liver and kidneys.

It remains in the blood and organs for up to 1 to 2 months. It can remain in bone for decades. (16)

Essential/Non- Essential


What is it and where is it found?

It is a naturally-occurring element found in rock in the earth's crust.

Forms/Uses of/Exposure to

It exists in three basic forms:

  1. Organic (methylmercury )
  2. elemental (metallic) mercury, and
  3. inorganic mercury compounds.

When mercury mixes with carbon (water) methylmercury forms.

Elemental or metallic mercury is a shiny, silver-white metal and becomes liquid at room temperature. It is used in older thermometers, fluorescent light bulbs, and some electrical switches. (17)

Inorganic mercury is a  compound that takes the form of mercury salt.

Mercury is considered toxic in any form.

How used by the body/Where stored in the body

It is found naturally in fish and water in trace amounts.  

However, industrial uses of mercury  (metallic) such as burning fossil fuels, use in pesticides, and mining has increased the amounts of organic mercury in the water and food chain to toxic levels.

It is stored in the brain, kidney, liver, hair, and skin.

Mercury can stay in the body for up to 1-3 weeks (but many health experts believe it remains in the body much longer). (17)

Essential/Non- Essential


What is it and where is it found?

A hard gray metal often found in minerals in combination with iron.

Forms/Uses of/Exposure to

Manganese is essential for the body to metabolize cholesterol, carbohydrates, and proteins.

It is also used in producing steel.

How used by the body/Where stored in the body

It can be found in grains and rice, soybeans, eggs, nuts, olive oil, green beans, and oysters.

It is stored in the bones, kidneys, and the pancreas.

It can stay in soft tissue for about 52-78 days and in bone for up to 7-8 years. (18)

Essential/Non- Essential


What is it and where is it found?

Tin is a silvery-white metal. It is found in igneous rock, plants, and water.  

It is used to create cans, containers, electrical materials construction materials, and transportation equipment. (19)

Forms/Uses of/Exposure to

Small amounts of tin are found in soil and as a result, in food.

We are exposed to higher levels of tin because it is used in food storage as can liners. (20)

How used by the body/Where stored in the body

How the body uses tin as a trace mineral is still being studied.  

Typically, you get additional amounts of tin in your body by breathing it in or eating it.

It is stored in soft tissue in the body, mostly in the lungs and intestines and stays in the body for 2-3 months. (21)

Essential/Non- Essential


What is it and where is it found?

A bluish-white metal that occurs in minerals.

In trace amounts, zinc is an essential micronutrient for both plants and animals.

It is used in alloys and as a protective coating in galvanizing iron and steel.

Forms/Uses of/Exposure to

It helps the immune system fight off invading bacteria and viruses. The body also needs zinc to make proteins and DNA.

A zinc deficiency can cause growth problems, inhibit wounds from healing, and increase chances of infection.

Too much zinc (either consumed or inhaled) can cause adverse health effects. (22)

How used by the body/Where stored in the body

It is in vegetables, seeds, and meat we eat and water we drink.

It is not fat soluble and is mostly stored in the muscle and bones.  

It stays in the body for about 16-43 days. (23)

Essential/Non- Essential


To Wrap Things Up...

While the heavy metal toxicity you hear about in the headlines is a real health issue, the truth is not all heavy metals are created equal.

As you now know, essential heavy metals/trace elements are necessary and beneficial to our health, while non-essential, inorganic heavy metals are toxic in high amounts. 

We are at higher risk toxicity today due to increased amounts of these heavy metal toxins in our environment.

When precisely a heavy metal becomes a heavy metal toxin is determined by how much and how long someone is exposed to it. The effects of exposure to any heavy metal depend on the form of the heavy metal, how and how long you experience exposure, your traits, and habits, and whether other chemicals are present. (24)  

Many health experts also believe genetics and family history may play a role in a person’s vulnerability to toxicity and their ability to detoxify heavy metals efficiently.

You want to minimize your exposure to the non-essential heavy metals by eating foods grown in non-contaminated soils (like organic or certified naturally-grown), filtering your water, avoiding some fish, seafood and other food products associated with high heavy metal content, avoiding lead-based paints, opting for porcelain fillings over amalgam fillings, etc. can all reduce your exposure.

Remember to know your heavy metals. Understanding how much of the essential heavy metals is the key to good health.

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