Talc is a mineral mainly consisting of the elements magnesium, silicon and oxygen. Talcum powder is made from talc. It absorbs moisture and helps cut down on friction. It is used in cosmetic products such as baby powder and adult body powders. The talc-based body powders at issue are Johnson’s Baby Powder and Shower to Shower. Plaintiffs contend that their use of those talc-based body powders for feminine hygiene purposes has caused their ovarian cancer. Defendants dispute general causation in this litigation.