Lung cancer risk and talc not containing asbestiform fibres: a review of the epidemiological evidence

Our plain-English summary of Lung cancer risk and talc not containing asbestiform fibres: a review of the epidemiological evidence, by P. Wild (Occupational and Environmental Medicine, 2006).

The study

• Author: P. Wild
• Journal: Occupational and Environmental Medicine
• Published: 2006;63(1):4-9
• Type of article: Review
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

A literature search was done and all epidemiological cancer studies mentioning talc as a risk factor were selected. The talc exposed populations were divided into three groups: (1) populations in which no other occupational carcinogen was mentioned (only talc millers satisfied this criterion); (2) populations of talc miners exposed to talc, quartz, and/or radon; and (3) other industrial populations in which talc is associated with quartz, nitrosamines, and asbestos depending on the study. No excess lung cancer mortality was found for the populations of talc millers exposed to high levels of talc but without any other potential carcinogen (SMR = 0.92, 42 cases) while the summary of mortality of talc miners exposed to quartz and/or radon was in excess (fixed effect SMR = 1.20, random effect RR = 1.85, 40 cases). Six studies in other industrial settings were identified. All reported increased lung cancer mortality among talc exposed workers but the talc exposure was confounded with other carcinogens and only one study was able to adjust on them. In conclusion, no increased lung cancer mortality was observed among talc millers despite their high exposure experience. In populations in which talc was associated with other potential carcinogens, some lung cancer excesses were observed.

In plain English

This single-author review examined epidemiological studies of lung cancer and talc not containing asbestiform fibres. Studies of fibrous talc and New York State talc workers were excluded, though three other-industry studies did not say whether their talc contained asbestiform fibres. Populations were grouped as talc millers, with no other occupational carcinogen mentioned; talc miners, also exposed to quartz and/or radon; and six other-industry populations where talc occurred with other carcinogens. For talc millers, the combined standardised mortality ratio for lung cancer was 0.92 (95% CI 0.65 to 1.25), based on 42 cases. For miners, the combined figure was 1.20 (95% CI 0.86 to 1.63), based on 40 cases. The miner studies differed significantly, owing to a very large risk among Vermont miners; a random-effect estimate was 1.85 (95% CI 0.68 to 5.05). In other industries, five studies reported relative risks above 1 and one, of Russian printing workers, gave 1.0; only one adjusted talc exposure for main confounders. The author concluded that talc millers showed no increased lung cancer mortality despite high exposure, but that few studies gave adequate exposure information.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review of published epidemiological studies (literature search updating the 1987 IARC review), with combined summary standardised mortality ratios (fixed effect, and random effect where the studies differed)
• Who was studied: Talc millers (Vermont, Norway, Italy, France, Austria sites B and C) and talc miners (Vermont, Norway, Italy). Six populations in other industries: US ceramic workers, Chinese and German rubber workers, US fibreglass workers, Russian women printing workers, and Norwegian women pulp and paper workers. Of 41 papers identified, 13 were scrutinised more closely.
• Exposure: Occupational exposure to talc not containing asbestiform fibres. Fibrous talc, New York talc and medical talc pleurodesis were excluded. Miners were co-exposed to quartz and/or radon. Other-industry workers were co-exposed to quartz, nitrosamines, aromatic amines or asbestos, depending on the study. Three other-industry studies did not say whether the talc contained asbestiform fibres.
• Main results:
  • Among talc millers, the combined lung cancer SMR was 0.92 (95% CI 0.65 to 1.25 in the text; 0.67 to 1.25 in Table 3), based on 42 cases. No heterogeneity between the studies was detected (chi-square 3.21, 5 df, p = 0.67).
  • Among the miller groups, only the French cohort had a relative risk above 1 (SMR 1.24, 21 cases, 95% CI 0.76 to 1.89). It was not statistically significant.
  • In a nested case-control study of the French and Austrian cohort, lung cancer odds ratios fell as cumulative talc exposure rose. Compared with non-talc-exposed subjects, the odds ratio was 0.60 for cumulative exposure of 400 to 800 years times mg/m3, and 0.73 above 800 years times mg/m3.
  • Among talc miners (also exposed to quartz and/or radon), the combined fixed-effect SMR was 1.20 (95% CI 0.86 to 1.63), based on 40 cases.
  • The miner studies differed significantly (chi-square 10.1, df = 2, p = 0.006). This was owing to a very large risk among Vermont miners (SMR 4.35, 5 cases, 95% CI 1.40 to 10.2). The random-effect summary estimate for miners was RR 1.85 (95% CI 0.68 to 5.05).
  • In the six other-industry studies, the text says all relative risks were above 1. However, Table 4 gives an SMR of 1.0 (6 cases, 95% CI 0.35 to 2.18) for Russian printing workers. Only the US fibreglass study adjusted talc exposure for the major confounders. Its adjusted odds ratio for high talc exposure was 1.36 (10 exposed cases, 95% CI 0.41 to 4.52), which the author called rather weak evidence.
  • The highest risks were in US ceramic workers exposed to non-fibrous talc and high silica. Ever-exposed workers had an unadjusted SMR of 2.54 (21 cases, 95% CI 1.57 to 3.88). The SMRs rose with longer duration of non-fibrous talc exposure but not with silica.
• The authors' conclusion: The author concluded that no increased lung cancer mortality was observed among talc millers despite their high exposure. The author added that few studies provide adequate exposure information and that further exposure-response studies are needed. In populations where talc was associated with other potential carcinogens, some lung cancer excesses were observed.
• Limitations the authors state:
  • There were few reliable studies of a possible dose-response effect.
  • Most studies gave only very sketchy exposure information.
  • In the miner and other-industry populations, other potential occupational carcinogens co-existed with talc, so unadjusted relative risks were confounded to some degree.
  • Three of the other-industry studies did not say whether the talc used contained asbestiform fibres.
  • Publication bias was considered more likely for studies in other industrial settings.
  • Talc worker cohorts likely included some unexposed employees. The author judged the effect on the SMRs to be virtually negligible.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Talc and vermiculite.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Talc, Asbestiform.

Related studies

• Exposure to asbestiform minerals and radiographic chest abnormalities in a talc mining region of upstate New York — E.F. Fitzgerald, A.D. Stark, et al. (1991)
• Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology — B.L. Finley, S.M. Benson, et al. (2017)
• Re: Brent L. Finley, Stacey M. Benson & Gary M. Marsh (2017): Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology, Inhalation Toxicology, DOI: 10.1080/08958378.2017.1336187 — M.M. Finkelstein (2017)
• Letter on: "Cosmetic talc as a risk factor for pleural mesothelioma: a weight of evidence evaluation of the epidemiology" — D. Mirabelli (2017)
• Carcinogenic hazards from inhaled carbon black, titanium dioxide, and talc not containing asbestos or asbestiform fibers: recent evaluations by an IARC Monographs Working Group — R.A. Baan (2007)
• A quantitative weight of evidence assessment of Hill's guidelines for causal inference for cosmetic talc as a cause of mesothelioma — A.M. Ierardi, A. Urban, et al. (2021)

Browse more research in Occupational and Environmental Medicine, or return to medical research.