fluoride
Discussed as a toxicant detrimental to health; it has no proven benefit, lowers IQ in children, shuts down thyroid function, and is a neurotoxin. It's found in most toothpastes and municipal water.
Videos Mentioning fluoride

No.1 Nitric Oxide Expert: This is the anti-aging cure no one is talking about!
The Diary Of A CEO
Discussed as a toxicant detrimental to health; it has no proven benefit, lowers IQ in children, shuts down thyroid function, and is a neurotoxin. It's found in most toothpastes and municipal water.

Long Muscle Length Training with Dr. Milo Wolf (Episode 125)
Stronger By Science

How to Improve Oral Health & Its Critical Role in Brain & Body Health
Andrew Huberman
A substance that can replace hydroxyapatite bonds in teeth, making them 'super physiologically strong'. Its presence in drinking water and toothpaste is a subject of polarized debate due to potential health concerns.

AMA #15: Fluoride Benefits/Risks & Vagus Nerve Stimulation
Andrew Huberman
A chemical compound discussed for its benefits in strengthening teeth and preventing cavities, but also its risks at high concentrations.