We have already explained that Chametz is any food derived or containing any derivative from the following five cereal-grains: wheat, rye, spelt, barley and oats (see here)
What happens if something which is a non-edible product contains Chametz? Is it forbidden for us to use it or to keep it during Pesach?
The answer is NO. The Halakha (Shulchan 'arukh 442:2, Mishna Berura 42:10) establishes that any non-food, anything which was never designed as an edible product, could be kept and even used during Pesach: For example: Cosmetics, paint, perfumes, soaps, detergents and any cleaning products, or any disposable utensils, aluminum foil, paper plates, paper cups, plastic forks, etc. In all these cases there is neither a need to check for the absence of Chametz or for any kind of Kosher for Pesach certification. Because, even if theoretically such a product would contains a Chametz ingredient, non edible Chametz is not considered Chametz (Penine Halakha "Pesach" p. 22-24).
According to Jewish law, however, the definition of a non-edible product is not restricted to human consumption. Animal food, for example, if it contains Chametz, cannot be used or even kept during Pesach. Therefore, dog-food, cat-food, birds-food or even fish-food, cannot be used or even kept during Pesach. Keep in mind that most animal food DO contain Chametz! Check this link for a list of Kosher for Pesach pet food.
In the next HOTD, B'H, we are going to discuss using and keeping during Pesach: medicines, oral hygiene products, dietary supplements, etc.