Foreign matter most commonly refers to the presence of unwanted or undesirable material present in foods or chemicals. When used in connection with foods, foreign matter may include packing materials inadvertently (or deliberately) included in the product, plant or meat products which should have been removed in manufacture or processing, vermin remains, stones, grit, sand, etc. Chemicals may be contaminated by a range of foreign matter, most commonly packing materials such as glass or polystyrene chips.