Volume 136: Talc and acrylonitrile

We are pleased to announce that the results of the recent IARC Monographs evaluation of the carcinogenicity of talc and acrylonitrile have now been published in The Lancet Oncology. This summary article presents the conclusions of IARC Monographs Meeting 136.

The IARC Monographs programme has previously evaluated talc (2006) and acrylonitrile (1998).

Acrylonitrile is a chemical with a high production volume that is mostly used as a monomer to prepare polymers for the manufacture of fibres for textiles, clothing and carpets, resins, synthetic rubber, and plastics. Occupational exposure occurs mainly in production industries via inhalation and dermal routes. For the general population, the primary source of exposure is tobacco smoke.

Talc was defined as mineral or synthetic talc, a hydrated magnesium silicate, including both the lamellar and fibrous (which includes asbestiform) forms of talc. Asbestiform talc is not asbestos; however, asbestos is present in some talc deposits and has been shown to contaminate some talc products. Talc is a mineral with a high production volume that is used in plastics, ceramics, paint, paper, roofing materials, rubber products, animal feed, food, fertilizers, cosmetics, and pharmaceuticals. It is also used in clinical settings for pleurodesis. Occupational exposure to talc dust occurs predominantly during mining and milling, mainly via inhalation, but can also occur among workers in downstream industries. The general population may be exposed via talc-based consumer products (such as body powders), and pathways of exposure include ingestion, inhalation, and dermal contact, including via the perineum.

The Working Group evaluated talc as probably carcinogenic to humans (Group 2A) on the basis of limited evidence for cancer in humans, sufficient evidence in experimental animals, and strong mechanistic evidence in human primary cells and experimental systems. This evaluation supersedes the previous classifications of “talc not containing asbestos or asbestiform fibres” and “perineal use of talc-based body powder”. “Talc containing asbestos” was not re-evaluated and retains its classification in Group 1, within “asbestos”. Acrylonitrile was evaluated as carcinogenic to humans (Group 1) on the basis of sufficient evidence for cancer in humans, sufficient evidence for cancer in experimental animals; and strong mechanistic evidence that acrylonitrile exhibits key characteristics of carcinogens in experimental systems.

The full scientific assessment will be published as Volume 136 of the IARC Monographs.

Stayner L, Carreón-Valencia T, Demers P, Fritz J, Sim M, Stewart P, et al.
Carcinogenicity of talc and acrylonitrile
Lancet Oncol, Published online 5 July 2024;
https://doi.org/10.1016/S1470-2045(24)00384-X

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