For definition of Groups, see Preamble Evaluation . Sepiolite is a hydrated magnesium silicate that occurs as a fibrous chain-structure mineral in clays in several areas of the world. The major commercial deposits of sepiolite are in Spain. It is also used as a drilling mud and as a carrier for fertilizers and pesticides. Meerschaum, a compact form of sepiolite, has been used for centuries for the production of smokers' pipes.
Occupational exposure occurs during the mining, milling, production and use of sepiolite.
No data were available to the Working Group. One study in sepiolite-exposed workers demonstrated clinical evidence of pulmonary function deficits. The results of one in-vitro study indicated that sepiolite was relatively potent in inducing superoxide anion release from both hamster and rat alveolar macrophages. Sepiolite is strongly haemolytic in some in-vitro assays. In a single study, samples of sepiolite from China, Japan, Spain and Turkey induced polyploidy, but not chromosomal aberrations, in cultured Chinese hamster lung cells.