Re: Why is mercury so bad for humans and animals?

Greetings.

I found the following which I believe answers your questions, excerpted from Resource 1.

Mercury (MeHg) (and perhaps Hg²⁺) exerts its toxic effects through numerous mechanisms. In neurons, MeHg disrupts calcium homeostasis by affecting both voltage-gated calcium channels as well as disruption of intracellular pools. MeHg, like cadmium, binds to sulfydral groups on cysteine, which may compromise the function of enzymes and ion channels. MeHg also interacts with DNA and RNA, resulting in reductions in protein synthesis, and disrupts the structure of the microtubules of neurons. MeHg poisoning produces oxidative stress in cells. This may occur through multiple mechanisms: decreased expression and activity of anti-oxidant enzymes, participation in a Fenton-like reaction by Hg²⁺, or disruption of electron transport in the mitochondria through inhibition of enzymes of the electron transport chain, and subsequent uncoupling of the e- transport chain and ATP synthesis (oxidative phosphorylation). Methylmercury has also been shown to induce programmed cell death (apoptosis) in exposed neurons.

1. Nutritional Toxicology of Heavy Metals: Cadmium and Mercury, Cornell University
2. Mercury Exposure in a Residential Community, CDC