No, I meant calcium carbonate. It is put into something a rat would eat. It then binds the rat's intestines. The rat dies because it can not eliminate its feces. It is non toxic; so it presents no harm to humans. Barium presents a health hazard to humans.
Calcium carbonate acts as a neutralizer and as a colour agent. I have used it a lot because I can purchase it for a very cheap price.
If you read some of my messages; you may be able to save a lot of money purchasing pyro-products.
I hate to waste money.
Prove it with a source or a reference that CaCO3 is used as a rat poison, because I cannot find anything on it. What's your point about barium posing a health hazard to humans? It's still an ingredient of some rat poisons, it's not my decision. I'm just starting the facts here, Anyka. About calcium carbonate being used in pyrotechnics, it's not used very much. It's used in the Veline colour system and some other orange formulae, some adhesive compositions but you're not getting too much further than that (See: Passfire formula base). Nor is it exclusively needed for anything, you can make do without it quite easily. It would one of the last items on my list of chemical acquisition.
Since you love to talk about saving money and purchasing chemicals useful for pyrotechnics for cheaper prices at non-pyro vendors, I thought I'll let you know there's better/cheaper places to obtain CaCO3. You can acquire it from chalk, from pharmacies, from garden supply houses and it's used in antacids. (See: Perigrin, Tom. Introductory Practical Pyrotechnics).
You can also purchase it for some ridiculously low price from a ceramic shop. Much cheaper than you'll ever find it as a poison (if that's even the case).