For 3 months, he had replaced sodium chloride with sodium bromide obtained from the internet after consultation with ChatGPT, in which he had read that chloride can be swapped with bromide, though likely for other purposes, such as cleaning.

I guess it's just as well that he didn't try substituting bleach.

EDIT: Also, aside from not looking the stuff up, whatever form he got the stuff in from the Internet has to have either not had a warning label or he ignored it.

Here's a container of sodium bromide on Amazon:

https://www.amazon.com/SpaChoice-472-3-5021-Sodium-Bromide-1-Pound/dp/B00IGERDJ8

On the front:

KEEP OUT OF REACH OF CHILDREN

CAUTION

See first aid statement and other precautions on back panel

On the back:

PRECAUTIONARY STATEMENTS

HAZARDS TO HUMANS AND DOMESTIC ANIMALS

CAUTION: Harmful if swallowed, absorbed, or inhaled through skin.

FIRST AID

IF SWALLOWED: Call a poison control center or doctor immediately for treatment advice. Have person sip a glass of water if able to swallow. Do not induce vomiting unless told to do so by the poison control center or doctor. Do not give anything by mouth to an unconscious person.