Some clay minerals occur naturally in a fibrous or lath-like crystal state as attapulgite and sepiolite. Because of their sorptive and colloidal properties, attapulgite and sepiolite have numerous industrial applications, mainly as additives in oil-drilling muds, in chemical fertilizers, pesticides, paints, adhesive products, bleaching agents, cosmetic compounds and phytosanitary products. World consumption of each is over one million tons annually. Acid-treated attapulgite is used in the composition of certain drugs used for the treatment of gastrointestinal diseases. Such drugs available commercially in France were analysed for their mineral content by transmission electron microscopy and found to contain attapulgite fibres [mean length: 0.9 micrometers (0.1-3.6); mean diameter: 0.05 micrometers (0.01-0.5)]. The haemolytic activities of a Spanish attapulgite sample and of three samples of drugs sold in France were greater or similar to that of UICC chrysotile asbestos. Attapulgite fibres were encountered in large quantities in the lung washing fluid of a patient suffering from lung fibrosis who had been exposed recently for three years during the processing of attapulgite material. Attapulgite fibres were also found in a urine sample from a patient who had ingested 6-9 g/day of an attapulgite drug for six months.