Sepiolite

Sepiolite is a fibrous magnesium silicate clay mineral, related to palygorskite. It is used in absorbents, pet litter, drilling fluids and fillers, and the massive form called meerschaum has long been carved into tobacco pipes. It is not asbestos, and its fibers are usually short.

Origin

The name comes from the Greek for cuttlefish, whose light, porous bone the mineral resembles. Large commercial deposits are mined in Spain and Turkey, among other places, and the meerschaum used for pipes has traditionally come from Turkey.

Significance in Asbestos Context

Sepiolite matters mostly as a point of comparison and a possible source of confusion. Like other fibrous minerals, its fibers can be counted on air samples analyzed by phase contrast microscopy, which cannot identify fiber type, so electron microscopy is needed to tell sepiolite from asbestos. In its late-1990s review, IARC concluded that sepiolite was not classifiable as to its carcinogenicity to humans, and the evidence suggests that its mostly short fibers are far less hazardous than asbestos. Some meerschaum deposits have been reported to contain other fibrous minerals, and some pipes were lined with other materials, so a history of meerschaum pipe use is sometimes explored in exposure histories. In product cases, the question is usually whether a sepiolite-based product also contained true asbestos.

Example Sentence

The lab confirmed that the fibers in the absorbent were sepiolite rather than chrysotile.

Related Terms

Palygorskite (Attapulgite), Mineral Fiber, Phyllosilicates, IARC Classification, Fiber Identification, Drilling Mud

Notes

• If a product contained fibrous clay, ask whether it was tested for asbestos by electron microscopy.
• Tell your lawyer about hobbies such as pipe collecting; they can be part of a full exposure history.