The thing about mercury is that it accumulates, but chlorine does not.

Mercury is mostly banned for being persistent pollutant, next after lead. There is no real safe level of mercury intake due to cumulative damage and hard for body to get rid of.

There is a safe, heck, required level of chlorine intake. (What is table salt?)

Mercury is not any superior at measuring temperature over a resistive electronic or a bimetallic thermometer, or alcohol capillary one. (Except the latter boils and freezes too easily, not a problem for body temperature.)

Although in theory electronic thermometers can be just as accurate in practice I've found that across brands the measurements fluctuate to an unacceptable degree.

What should we know about bleach?

For one, not to mix it with vinegar. Chlorine gas.

There was a spate of TikTok's recommending mixing them for cleaning purposes. To the horror of many.

Drink elemental mercury and you'll be fine, it'll just pass through and you'll shit it out.

Drink bleach and it'll probably kill you or at least give you terrible injuries.

Ok, guess I should have asked, what should we know about bleach besides the warnings prominently printed on the bottle. Tbf I really don't expect everything in my house to be edible.