CTFA QUESTIONS SCIENTIFIC BASIS OF TALC OVARIAN CANCER WARNING in June 16 comments to FDA. In response to a November 1994 citizen petition filed by the Cancer Prevention Coalition seeking carcinogenicity warnings on talc-containing products, the Cosmetic, Toiletry and Fragrance Association contended that "such labeling is without scientific basis and is unnecessary to protect the health of consumers."

"The available literature and the experience of manufacturers provide no evidence that cosmetic talc, when used as intended, presents any health risk to the consumer," CTFA maintained. A label warning, the trade association added, would "unnecessarily alarm consumers regarding the use of safe cosmetic products."

The CPC petition urged FDA to require cosmetic talc products to bear a warning label that might read: "Talcum powder causes cancer in laboratory animals. Frequent talc application in the female genital area increases the risk of ovarian cancer" ("The Rose Sheet" Dec. 5, 1994, p. 6). In support of its petition, CPC cited results from a study released by the National Toxicology Program in 1993. The study found "clear evidence" of talc carcinogenic activity in the lungs of female rats, "some evidence" in male rats and "no evidence" in male or female mice ("The Rose Sheet" Nov. 8, 1993, p. 3).

CTFA questioned the reliability of the NTP study, contending that it "has been subject to severe criticism" and has "questionable relevance with regard to prediction of human risk."

Citing several papers written on the NTP study, CTFA noted that "the major criticism of the...study is the failure to include exposure levels which did not lead to lung particle overload." CTFA explained that particle overload is caused by the "impairment of lung clearance mechanisms." The exposure levels used in the study -- concentrations of 6 or 18 mg/m3 -- exceeded the maximum tolerated dosage for talc resulting in the lung impairment and the subsequent particle overload, CTFA said.

"The rat tumor response is thus very likely a secondary effect of the particle overload phenomenon," CTFA said based on a 1995 paper by G. Oberdorster on the effect of lung particle overload in the NTP study. CTFA argued that such an interpretation is supported by the absence of tumors in the mice study. The comments suggest that the "rat lung tumors associated with a high pulmonary particle load appears to be a very species-specific response to non-fibrous particles." Thus, CTFA asserted, "the relevance of these responses with regard to extrapolation to humans is...highly suspect."

CTFA also questioned the applicability of the NTP study results to human risk assessment due to the industrial grade of the talc sample used in the study. The extremely small particle size of the talc sample (approximately 1.2 microns with a top size of about 10 microns), CTFA declared, "is not characteristic of material used for cosmetic talc applications," which have a typical size of approximately 10 microns and can approach 45 microns in size.

Furthermore, CTFA noted, human exposure to talc, which occurs generally through dermal application of products, "is considerably lower than exposures which result in rat lung tumors." Normal product use results in a human inhalation rate of about 2,000-20,000 times lower than that in the NTP study rats, the association pointed out.

CTFA also highlighted the conclusions of an expert panel convened at a 1994 workshop on talc sponsored by FDA and the International Society of Regulatory Toxicology and Pharmacology. The panel found that "because of the extreme doses and the unrealistic particle sizes of the talc employed, [and] because of the negative results in mice and male rats...the positive talc bioassay results in female...rats are likely the result of experimental artifact and non-specific, generic response of dust overload of the lungs, and not a reflection of a direct activity of talc."

Responding to CPC's concern that talc may include asbestos particles, CTFA said the suggestion is "erroneous" and "based on outdated...evidence." The trade association maintained that "appropriate selection of mine site, careful mining procedures and the utilization of modern beneficiation techniques have...safeguarded against asbestos contamination." CTFA also pointed out that in 1986 FDA concluded that no health hazard existed regarding asbestos contamination in cosmetic talc. The association declared that "no new evidence has arisen which would suggest a conclusion to the contrary."

Regarding CPC's contention that perineal use of talc increases the risk of ovarian cancer, CTFA asserted that a review of available epidemiological evidence "suggests only a weak statistical association between perineal talc use and ovarian cancer, the significance of which is not considered scientifically or medically meaningful."

CTFA noted that seven case control studies and one cohort study have been conducted to examine the possible association between talc use in the female genital area and an increased risk for ovarian cancer: five studies found an increase in risk of ovarian cancer with talc use, with odds ratios ranging from .776 to 4.79; one study was inconclusive; one study showed no significant finding; and one study found no association. The results from these studies, CTFA asserted, "are inconsistent and ambiguous" and contain "numerous confounding variables, (e.g., interview case/control comparisons, failure to adequately address key independent risk factors, etc.) which characterize much of the epidemiological research in this area."

In addition, CTFA maintained, these statistics "are unsupported by evidence of a plausible biological mechanism by which talc could cause ovarian cancer." Talc particles "have no inherent locomotive capability," CTFA said, and "available histological and physiological studies provide no concrete basis to conclude that talc can plausibly migrate to the ovaries from the perineal region." In addition, CTFA asserted, those studies that have investigated the potential translocation process of talc in both animals and humans "are so fraught with problems as to render the results of such studies ambiguous."

The trade association also pointed out that the etiology of ovarian cancer is not understood. Although evidence suggests that "a variety of intrinsic and extrinsic risk factors may be involved...it is significant in this respect that a thorough review of the toxicology of talc reveals no evidence of any genotoxicity," CTFA declared. The association based these comments on talc and ovarian cancer on a 1994 paper by A. Wehner.

CTFA noted that the expert panel at the FDA/ISRTP talc workshop found that the "epidemiologic studies have provided weak and conflicting risk signals for [the] association [between talc use and ovarian cancer], and it is likely that further studies may prove adequate to raise concern at a level sufficient to warrant regulatory or public health measures."

CTFA questions scientific basis of CPC's requested talc ovarian cancer label warning.

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