The above headline is a quote from an insert in the package. Well this is exactly why I bought these things- to guard "from toxic and dangerous substances". They should have mentioned this on Amazon's site. If they had I would have saved my money and bought devices that could actually be used to guard children from "toxic and dangerous substances." I am disappointed as I find Amazon's write up to be misleading in what it does not say! The supplier and Amazon should know and do better.