Mr. John Addison BSc, F Min Soc, Consultant Mineralogist specialising in the identification and analysis of asbestos and industrial minerals, their toxicity and effects on human health, has accepted to reply to this question.

Asbestiform is a term that is used to describe the mineral habit of minerals that are formed in a fibrous state that resembles asbestos. The American Society for Testing Materials (ASTM) has defined asbestiform minerals as mineral fibre populations generally having the following characteristics when viewed by light microscopy:

•  Many particles with aspect ratios ranging from 20:1 to 100:1 or higher (greater than 5µm in length);
•  Very thin fibrils generally less than 0.5µm in width; and
•  In addition to the mandatory fibrillar crystal growth, two or more of the following attributes:
  - parallel fibres occurring in bundles,
  - fibres displaying splayed ends,
  - matted masses of individual fibres, and
  - fibres showing curvature.

The common asbestos minerals fit this description perfectly, but in addition they are characterised by having high tensile strength and pronounced durability.

A number of other minerals including gypsum, calcite, brucite and talc can, rarely, occur in a fibrous habit that can be described as asbestiform. The use of the term is accurate in that the minerals in this unusual habit do resemble asbestos, but they do not have the other physical and chemical properties of asbestos. In particular they do not have any of the toxicological properties of asbestos.

In the case of talc, this mineral habit is rare and there are few proven occurrences of talc in this form. Asbestiform talc in this sense is encountered as a geological curiosity, mostly in the mineralogical collections of enthusiasts, and has no significant public health risk implications.

Certain other materials have also been referred to as `asbestiform talc’. A small number of talc deposits, mostly in the eastern parts of the USA, have been found to contain unusual minerals that appear to consist of intimate mixtures of talc and anthophyllite, or talc and tremolite. These mixtures of talc and amphibole were first recorded in the 1980s and are sometimes called talcboles, referring to the fact that, even in single small crystals, the crystal lattice appears to be an inter-lamination of talc and amphibole structures. These crystals can form or separate into long thin fibres that are very similar to asbestos in appearance. These fibres are not asbestos, and there is little evidence to show that they have the same toxicological properties as asbestos. None of these unusual minerals have been found in other talc deposits around the world.

Finally, the term `asbestiform talc’ has also been applied recently to talc containing asbestos. This is a misuse of the term since `asbestiform’ can only ever be used to describe a mineral habit. The correct term for this mixture is simply talc containing asbestos.

Thanks to high standards of quality control and selective mining methods where necessary, the commercial talcs supplied by EUROTALC Members do not contain asbestos as defined by the European directive 2009/148/EC, when analysed by conventional methods. This statement is based upon verification by certified independent laboratories.

Crystalline silica is one of the most common minerals on our planet, representing about 12% of the earth’s crust. As in most naturally occurring mineral substances, talc can contain some crystalline silica (generally less than 5%). The main health effect of exposure to crystalline silica is silicosis, a progressive and impairing fibrosis. This illness develops as the consequence of long term exposure to excessive amounts of respirable crystalline silica particles. A recent evaluation (IARC – International Agency for Research on Cancer – 1997) concluded that crystalline silica is a human carcinogen. This conclusion was limited to certain occupational circumstances only.

There is a consistent body of evidence supporting the fact that carcinogenic effects, if any, are secondary to the well known fibrogenic effect of crystalline silica. At the present stage, all established evidence suggests that prevention is the appropriate way of managing this issue. The silicosis risk should be evaluated and managed at the workplace, where the product is handled, essentially by complying with the occupational exposure limits (OEL) for quartz.

There is no clinical evidence to suggest that talc causes lung cancer. Mortality studies conducted over the last 20 years in France, Austria, Italy and Norway on talc workers exposed to talc dust all of their adult lives have shown that there is no excess cancer risk amongst these people compared to the population at large. Thus the silica content of these talcs shows no evidence of being carcinogenic.
For more information on crystalline silica and the social dialogue agreement for the good handling and use of crystalline silica and products containing it, visit www.nepsi.eu.

A carcinogenesis inhalation bioassay of talc was conducted in rats and mice by the US National Toxicology Program in 1993 (NTP 1993. Toxicology and Carcinogenesis Studies of Talc (CAS n° 14807-96-6) (Non-Asbestiform) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). TR-421 Research Triangle Park, NC, National Toxicology Program).

While it was already reported in the literature that talc does not cause tumours in hamsters, this study showed that it does not cause tumours in mice either, but induces some tumours in rats, especially female rats.

The International Society of Regulatory Toxicology and Pharmacology and the US Food and Drug Administration cosponsored a Workshop organised 31 January-1 February 1994 on “Talc: Consumer Uses and Health Perspectives”. The event brought together over 20 leading experts in epidemiology, risk assessment, toxicology and clinical medicine. They deliberated on the latest studies conducted on talc and its use in consumer products. In the Journal Regulatory Toxicology and Pharmacology 21 (2) April 1995, the Executive Summary states: “In regard to the NTP talc bioassay in rodents, it (the expert panel) found that because of the extreme doses and the unrealistic particle sizes of the talc employed, because of the negative results in mice and male rats, because of the lack of tumor excess at the low doses, and because of the clear biochemical and cytological markers of excessive toxicity in female rats, the positive talc bioassay results in female F344/N rats are likely experimental artefact and non generic response of dust overload of lungs and not a reflection of a direct activity of talc” It can therefore be concluded that the combination of very serious flaws in this study clearly rule it out as an indicator of carcinogen hazard to humans. No additional work has been reported since which demonstrates a direct impact of talc in animals.

Below is an update timeline on studies related to body powders containing talc:

1976 – Industry, in conjunction with governmental agencies, develops specifications for cosmetic talc requiring that no detectable asbestos be present in such personal care products.

1982 – First epidemiological study suggesting a potential link between perineal talc exposure and ovarian cancer was published by Cramer et al. This was a case-control study and such case-control studies can have significant limitations, including issues with bias and confounding, that make their interpretation difficult. Between 1982 and 1994 – The next four case control studies show no overall statistically significant increased risk in ovarian cancer in ever vs. never talc users.

1994 – FDA sponsors a conference reviewing the science and medical evidence on talc with academics, regulatory officials, and industry and an FDA official reports that “talc has proven to be among the safest of all consumer products.”

2000 – The federal government’s National Toxicology Program declines to list talc as a carcinogen due to confusion over talc containing and not containing asbestiform materials.

2000 – The large prospective Nurses Health Study of over 32,000 talc users and 47,000 non-users shows no overall association with ever talc use and epithelial ovarian cancer and no increase in risk of ovarian cancer with increasing frequency of use, concluding that their results “provide little support for any substantial association between perineal talc use and ovarian cancer risk overall; however, perineal talc use may modestly increase the risk of invasive serous ovarian cancer.”

2003 – Dr. Huncharek publishes a meta-analysis of 11.933 subjects from sixteen observational studies concluding “In summary, pooling data from the sixteen available studies examining the relationship between perineal use of cosmetic talc and the development of invasive epithelial ovarian cancer failed to show evidence of a causal relationship”.

2006 – A Working Group for the International Agency for Research on Cancer (IARC) classifies talc as a Group 2B agent, meaning that although a positive association has been observed in some studies for which a causal association may be credible, “chance, bias, and
confounding cannot be ruled out with reasonable confidence.”

2008 – Epidemiologists from the IARC Working Group, reviewing 20 case-control studies with mixed results and the one large prospective Nurses Health Study, state that “The current body of experimental and epidemiological evidence is insufficient to establish a causal association between perineal use of talc and ovarian cancer risk.”

2010 – A second report from the prospective Nurses Health Study with longer follow up finds no significant increase in risk of ovarian cancer generally or of serous ovarian cancer specifically in talc users.

2014 – The FDA declines two “citizens’ petitions” requesting a warning about ovarian cancer on talc-containing body powder products.

2014 – The large prospective Womens’ Health Initiative study of 32,000 talc users and 28,000 non-users concludes that “perineal powder use does not appear to influence ovarian cancer risk.”

2015 – The National Cancer Institute’s Physicians Data Query (PDQ) summary for health care providers lists genital talc use as a factor for which there is “inadequate evidence of an association” with ovarian cancer.

2015 – The Cosmetic Ingredient Review’s Expert Panel on talc concludes that “talc is safe in the present practices of use and concentration described in [its] safety assessment” including an evaluation of genital talc and ovarian cancer.

2016 – The “Associazone Italiana per la Ricerca sul Tumore” (AIRC) publishes on its website a commentary entitled “Does the use of perineal talc increase the risk of ovarian cancer?” The conclusion of the commentary is “those who used the genital talc don’t have reasons to be alarmed. Most studies cannot show a relationship of cause-effect between the use of genital talc and the little increase of risk observed in some retrospective case-control studies”.

The health effects of talc inhalation in humans working with talc in an occupational context have been assessed through a number of epidemiological surveys.
The most important of these tracked mortality rates among the worker population of the largest talc mine and milling plant in the world, in France, over a period of 51 years from January 1945 to December 1996. Similar studies have also been made on talc workers in Austria and Italy.

The most recent of these studies:

• WILD P. and ColI. A cohort mortality and nested case-control study of French and Austrian workers. Occup. Environ. Med 2002; 59; 98-105.
• COGGIOLA M. and Coll. An update of a mortality study of talc miners and millers in Italy, Am. J. Indust. Med. 44, 2003, p 63-69

conclude that there is no excess of lung cancer or excess of any other type of cancer amongst these populations. Similarly, pleural or peritoneal mesotheliomas, known to be related to asbestos mineral exposure, were not found.

Likewise, a review of the epidemiological evidence, conducted in 2006, (Lung cancer risk and talc not containing asbestiform fibres: a review of the epidemiological evidence”, by Pascal Wild. Published in Occup. Environ. Med. 2006) similarly concludes that “no increased lung cancer mortality was observed among talc millers despite their high exposure experience. In populations where talc was associated with other potential carcinogens, some lung cancer excesses were observed.”

All this independent research has been published in peer-reviewed journals and EUROTALC members have been commended by the World Health Organisation for their contribution to these studies.
The results above concur with the position of the United States National Toxicology Program which ruled in October 2005 that existing scientific data were insufficient to identify talc as a cancer causing agent. Consequently, talc was withdrawn from review for the 12th Federal Report on Carcinogens (RoC).

Similarly, on February 14, 2006, the World Health Organization’s International Agency for Research on Cancer (IARC) completed its reassessment of the potential carcinogenicity of talc not containing asbestos or asbestiform fibres. After reviewing the epidemiological studies published since IARC’s first evaluation of talc in 1987, the Working Group concluded that there was inadequate evidence for the carcinogenicity to humans of inhaled talc not containing asbestos or asbestiform fibres and agreed to continue with its classification in Group 3. This means that occupational exposure to talc, on which this categorization is based, is not a risk factor for lung cancer or any other cancers of the respiratory system in humans.

On 5 December 2000, the US National Institute for Environmental Health Sciences (NIEHS) issued a press release announcing that, among other substances, talc was to be considered for listing in the next 10th Federal Report on Carcinogens (RoC). To assist the US National Toxicology Program (NTP), the NTP Board of Scientific Counsellors reviewed the substances during a public hearing organised 13 – 15 December 2000 at the Wyndham City Center in Washington. (Official notice of the meeting was given in the Federal Register Vol. 65 n° 201 p. 61352 et sq, updated in Fed. Reg. Vol. 65 n° 233 p. 75726 et sq.)

The result of the December meeting was that the NTP Board of Scientific Counsellors recommended not to list “talc (non asbestiform)” in the 10th ROC. No decision has yet been reached for “talc (asbestiform)”.

During this public meeting, several experts presented arguments against listing talc (asbestiform as well as non asbestiform) as a reasonably anticipated human carcinogen. EUROTALC’s position was submitted in writing and was presented at the hearing by John Addison and Arthur Langer with regard to the confusion surrounding talc and asbestos, and by Allen Gibbs with regard to epidemiological and pleurodesis evidence. I

In October 2005, NTP concluded that existing scientific data “provided inadequate characterization of the materials under study to reach definite conclusions concerning the specific substances responsible for the range of adverse health outcomes reported.” Consequently, the two talc nominations, i.e. cosmetic talc and occupational exposure to talc, were withdrawn from review for the 12th RoC.​