Talc (Mg3H2(SiO3)4)

Endpoint summary

Description of key information

Conclusion

 

In studies in rats, mice, guinea-pigs and hamsters that used radioactive tracer techniques, no intestinal absorption or translocation of ingested talc to the liver or kidneys was detected (Wehner et al., 1977; Phillips et al., 1978).

No translocation of talc into the ovaries was detected after single or multiple intravaginal applications of talc to rabbits (Phillips et al., 1978) or monkeys (Wehner et al., 1985, 1986).

 

There are no indications that orally or inhalation administered talc is absorbed by rats, mice, hamsters or guinea pigs. 

Talc administered into the pleural space of rats is distributed systemically throughout the body.

Talc elimination of radioactivity was determined in the urine and faeces and thereforeTalc (Mg3H2(SiO3)4) has no bioaccumulation potential.

 

Exposure to talc does not lead to any relevant dermal absorption. Therefore designation with an “H” is not necessary.

There is no information that would justify a designation of talc with “Sa” or “Sh” (for substances which cause sensitization).

Nor can a classification of talc into a category for germ cell mutagens be justified on the basis of the available data.

There was no evidence of carcinogenic activity in male or female B6C3F1 mice.

A bioassay using rats was performed by the NTP to determine the carcinogenic potential of non-asbestiform, cosmetic-grade micro-talc following exposure by inhalation, and it was concluded there was some evidence of carcinogenic activity in male F344/rats, and clear evidence of carcinogenic activity in female F344/N rats. The rats were exposed to 6 mg/m3 (MMAD 2.7 ± 1.9 μm) or 18 mg/m3 (MMAD 3.2 ± 1.9 μm) talc for 6 h/day, 5 days/wk, for 113wks (males) or 122 wks (females).Concerns have been raised about this study, including concerns that micronized talc having a significantly smaller particle size distribution than cosmetic talc was used, aerosol concentrations were not properly controlled, proper procedures for dose selection were not followed resulting in the MTD being exceeded at both concentrations tested, and particle overload in the lungs was most likely the cause of the adverse effects reported.

The talc used in the this study was a commercially available microtalc whose dimensions of < 10 µm were distinctly finer than the cosmetic powder normally used.

Therefore, the study is not conclusive with regard to a possible carcinogenicity of large talc platelets or talc fibres.

There are conclusive but not suffcient data for the classification of substance Talc (Mg3H2(SiO3)4) with regard to carcinogenicity.

Not classifiable as a human carcinogen. /Talc containing no asbestos fibers/ [American Conference of Governmental Industrial Hygienists TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.,, 2008, p. 54

It is concluded that talc not containing asbestos or asbestiform fibres is safe in the present practices of use.

Additional information

SUMMARY

 

Talc was used in over 2800 cosmetic formulations and, according to concentration of use talc is used at up to 100% in cosmetic formulations. Talc is used in almost every category of cosmetic product, and it is used in products that may be applied to baby skin, products that could be incidentally ingested, products used near the eye area or mucous membranes, and in products that are sprayed. The particle size of talc raw material varies widely by product type and by manufacturer.

Talc has many commercial uses and it has pharmaceutical use. It is used as a color additive in drugs and is exempt from certification. Sterile talc is approved as a sclerosing agent. Talc is not allowed for use on the surface of medical gloves. It is used in the production of foods, and it is approved as an indirect food additive as a color.

 

 

Talc has a TLV (respirable fraction) of 2 mg/m3 as a TWA. Human pulmonary effects of talc include diffuse interstitial fibrosis and progressive massive fibrosis (often called complicated pneumoconiosis). In occupational exposure studies, statistically significantly elevated SMRs for silicosis and silico-tuberculosis were observed in an early study of talc miners and millers in the Italian Piedmont region exposed to talc that contained no fibrous material except for tremolite micro-inclusions; SMRs were statistically significantly reduced for malignant neoplasms, including lung, bronchial and tracheal cancers. A follow-up of this group found statistically significant increases in mortality, which were attributed primarily to non-malignant respiratory diseases among the miners. A cohort study of talc miners and millers exposed to talc and magnesite containing trace amounts of quartz, tremolite, and anthophylite found no statistically significant SMRs for all causes, all cancers, or diseases of the circulatory system or respiratory tract. The results of several other epidemiological studies were likely confounded by the presence of up to 3% silica or 6% actinolite in the talc, exposures to high concentrations of silica with or without exposures to fibrous talc (tremolite), or concurrent exposures to radon daughters. A meta-analysis of studies of miners and millers who worked with non-asbestiform talc reported summary SMRs for lung cancer of 0.92 (95% CI: 0.67-1.25) for millers in five countries exposed to high levels of talc without exposure to other occupational carcinogens, and 1.2 (95% CI: 0.86-1.63) for miners in 3 countries exposed to high levels of talc as well as to silica or radon and radon daughters.

Studies examining radiological, lung-function and clinical parameters in talc miners and millers and rubber workers found some statistically significant changes.

 

In exposure-during-cosmetic use studies, the researchers noted that there was a wide variation in talcing times and methods, often by the same volunteer during different applications. Reported talcing times ranged from 17 sec to 31 sec. Endobronchitis and airway stricture was reported in one case in which a subject applied large amounts of talc powder to her face. In another case, a chronic pulmonary granulomatous reaction was reported in a subject who applied “non-powdering talc” to her face for 20 yrs, followed by use of talcum powder 2-3 times a day for a 10-yr period.

 

 

Numerous epidemiological studies have been performed examining the risk of ovarian cancer following talc exposure. Among the epidemiological investigations reporting statistically-significant associations, the relative risk estimates ranged between 1.0 and 2.0 and were barely statistically significant. Many physiological, sociological, and exposure factors have been linked to ovarian cancer, a number of them with a stronger association than that of hygienic use of cosmetic talc, but causality has not been established for any of them. Most of the epidemiological studies found no trend of increasing ovarian cancer risk with increasing exposure duration or frequency or cumulative exposure, despite a five-fold difference between the lowest and the highest exposure groups. Several of these studies reported an apparent inverse trend. The results of several epidemiological studies suggested that medical procedures expected to prevent the translocation of talc to the ovaries, such as tubal ligation or hysterectomy, reduce the relative risk estimates associated with talc use.

 Other studies found no difference in relative risk between women who had tubal ligation or hysterectomy and women who did not have these procedures. One study reported inverse exposure-effect trends with duration of talc exposure after adjusting for tubal ligation. The use of talc-dusted condoms or diaphragms (including diaphragms known to have been stored in talc powder), which would clearly result in exposure close to the cervical opening, was not associated with an increased estimate of relative risk of ovarian cancer.

 

 

The previous MAK value of 2 mg/m3 for talc has been withdrawn since more recent data from animal studies have indicated a retardation of clearance in this concentration range and changes in pulmonary function are still observed in humans.

Exposure should be below the general threshold limit value for dust (respirable fraction) of 1.5 mg/m3. Since talc always also contains very biopersistent fibres of the WHO definition, monitoring the concentration of talc in air should take into account the concentration of talc (in mg/m3) and the fibre fraction contained in the talc.

Exposure to talc does not lead to any relevant dermal absorption. Therefore designation with an “H” is not necessary.

There is no information that would justify a designation of talc with “Sa” or “Sh” (for substances which cause sensitization).

Nor can a classification of talc into a category for germ cell mutagens be justified on the basis of the available data.

 

It is concluded that talc not containing asbestos or asbestiform fibres is safe in the present practices of use.