Excipient (pharmacologically inactive substance)
What is it?
Magnesium silicate (MgSiO3) when hydrated is most commonly known as "talc". In the pharmaceutical industry it is used as an anticaking agent to improve powder flow in tablet compression. Talc is used cosmetically in talcum and baby powder as an adsorbent. Talc has been reported to be used in some food products, and is generally recognized as safe by the FDA.
Natural talc contains asbestos, a substance that may lead to lung cancer. However, talcum products used in cosmetics have been free of asbestos since the 1970s. Some studies have reported small increases in ovarian cancer with the use of asbestos-free talcum powder, but studies are conflicting and the results are not definitive. The American Cancer Society suggests corn starch-based cosmetics might be an alternative in those concerned about talc use.