Definition. Talcum powder is a powder made from a mineral called talc. Talcum powder poisoning may occur when someone accidentally or intentionally breathes in or swallows talcum powder.This is for information only and not for use in the treatment or management of an actual poison exposure.efinition. Talcum powder is a powder made from a mineral called talc. Talcum powder poisoning may occur when someone accidentally or intentionally breathes in or swallows talcum powder.