ELi5: why are almost all heavy metals toxic? What do they do in the body?
In: Chemistry
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Here 2 videos made by Chubbyemu that explain what happened to [a child who ate lead paint](https://youtu.be/5qHxEjINCAg) and [a scientist who spilled a very little amount of organic lead on her hand](https://youtu.be/NJ7M01jV058)
I’m not a scientist, nor a biologist or a medic, but I assume that heavy metals do cause problems when they “bound” with our bodies
not a complete answer but I know that in the body lead gets confused for calcium. calcium not only is a key ingredient in building bones but it helps the nervous system in the brain transmit signals. when the body replaces some of the calcium in the brain with lead it starts to disrupt the whole nervous system. Leading to mental disabilities all the way up to death. I believe that mercury acts in a similar way. Hence the term ‘Mad as a hatter’ since people who used to make hats out of animal skins used to use mercury to shape them. They would go ‘crazy’ from mercury poisoning.
Here is a good review of [Mechanism and Health Effects of Heavy Metal Toxicity in Humans](https://www.intechopen.com/books/poisoning-in-the-modern-world-new-tricks-for-an-old-dog-/mechanism-and-health-effects-of-heavy-metal-toxicity-in-humans)
First, **Many metals are necessary** and do not cause health problems.
>copper, cobalt, iron, nickel, magnesium, molybdenum, chromium, selenium, manganese and zinc have functional roles which are essential for various diverse physiological and biochemical activities in the body.
Second, “**the dose makes the poison**”, so when you get too high a dosage of one of the toxic forms of a toxic product you start to have problems. Some are toxic in smaller doses than others.
>cadmium, mercury, lead, chromium, silver, and arsenic in minute quantities have delirious effects in the body causing acute and chronic toxicities in humans.
The specific mechanism of toxicity is different for these different metals. These are common pathways
1. oxidative stress and oxidation of biological molecules
2. Heavy metal-induced carcinogenesis
3. Heavy metal-induced neurotoxicity
This tends to happen after they are acidified in the stomach, to a 2+ metal ion, which then bonds permanently to places where it causes trouble.
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