I visited my mum once after having some dental work. I asked if she had any salt, as the dentist told me to rinse with salt water a few times a day. She told me there was a bag of dishwasher salt in the cupboard. I had some qualms about this, so very carefully read the label, and it said “not for human consumption”. I pointed this out, and she said “they just say that”.
She turned out to not have any salt because she doesn’t believe in seasoning food (and doesn’t like things with flavours like crisps) and gets annoyed when people use salt and pepper at the table. So I had to go and buy some rather than poison myself with dishwasher salt.