Filth

Contaminants in food such as hairs, rodent and bird droppings, and fragments of insects and feathers. Their presence signals poor hygiene in processing and handling. Filth tests, microscopic examinations for these contaminants, are used as an index of sanitary conditions, and regulators set defect action levels. The US FDA’s Defect Levels Handbook sets action levels — e.g. insect fragments per 50 g of flour — acknowledging that zero defects are unattainable in agricultural products. Exceeding them signals insanitary conditions and can trigger import refusal; good manufacturing practice and pest management keep counts well below limits.