After reading so many responses to posts about the lawsuit award in social media and having questions myself (Shouldn't the number of women diagnosed with ovarian cancer be higher if Talc caused the disease? How does the talc affect the ovary to cause cancer? How does the talc affect the ovary when it inside the body not a surface organ?)
I delved further.
Study 1: Perineal Talc Use and Ovarian Cancer :A Critical Review
One of the thorough reviews of talc and ovarian cancer I ran across was this article published in 2008 by Muscat - Perineal Talc Use and Ovarian Cancer :A Critical Review. (Perineal = cosmetic talc)
In the early 1970's the lung cancer asbestos link was being studied. One asbestos study using guinea pigs (1969) showed asbestos in the animal's ovaries. While limited data in another study showed an increase in mortality rates due to Ovarian cancer for women who worked in the asbestos industry in another study ( 1982) showed. So talc became suspect as a cause of ovarian cancer. Please not that a study done in 2008 showed no increase risk for those working in the asbestos industry.
Is Talc the same as Asbestos? "Asbestos is morphologically (form and structure) distinct from talc and belongs to different silicate mineral groups and subgroups." In other words, Talc which is a member of a different silica group does not behave the same ("a mineral’s fibrous pattern of growth") as asbestos.Thinking along these lines carbon is the same in coal and a diamond it is all how the atoms are arranged.
How does Talc cause cancer?" "Asbestos fibers in the lung initiate an inflammatory and scarring process, and it has been proposed that ground talc, as a foreign body, might initiate an inflammatory response." We are not sure of the bodies response to talc although the formation of ANTI-MUC1 antibodies when the body has been exposed to talc has been proposed in the past.
How does Talc enter the ovaries?"Perhaps the most fundamental unanswered question on perineal dusting is whether powder applied to skin surfaces surrounding the external genitalia actually enter the adult female genital tract. It is uncertain whether dusting contaminates the vagina or cervix and if so under what hygienic conditions. The issue of particle retrograde migration from the cervix to the ovaries assumes that talc particles migrate upwards against both gravity and the downward flow of vaginal mucous and menstrual fluids." ..."In early studies, it was assumed that the vagina was the route of exposure, although as noted previously occupational studies indicated that inhaled particles could migrate from the lungs to the ovaries."
A study of silica in ovaries by Heller showed "Some samples that had no measurable talc counts were obtained from women who reported regular talc dusting, whereas other samples with high concentrations were obtained from women who reported no genital talc use."
The conclusion section of the Muscat study, states, "lifetime whole body exposure experiments in female laboratory rats found that ovarian tissue was not contaminated with talc and that ovarian tumor incidence was not increased (Boorman and Seely, 1995). "... "In addition, inhaled talc in mining and milling operations is not associated with increased pulmonary tumors. IARC classified inhaled talc that does not contain asbestos fibers as a group 3 carcinogen (e.g. inadequate evidence in humans), and the likelihood that talc could selectively induce ovarian cancer and not lung cancer, and at exposure concentrations presumably orders of magnitude lower than that in occupational settings needs to be weighed."
Study 2: Perineal Powder Use and Ovarian Cancer