Industrial-grade talc exposure and the risk of mesothelioma

Our plain-English summary of Industrial-grade talc exposure and the risk of mesothelioma, by B. Price (Critical Reviews in Toxicology, 2010).

The study

• Author: B. Price
• Journal: Critical Reviews in Toxicology
• Published: 2010;40(6):513-30
• Type of article: Review
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Industrial-grade talc deposits are complex mixtures of mineral particles and may vary substantially in composition across small geographical areas. Typical industrial-grade talc includes amphibole cleavage fragments, platy talc, serpentine minerals, talc in fibrous form, and a minor presence of transitional fibers. Industrial-grade talc was erroneously determined to be an asbestos-containing material due to an unintended consequence of Occupational Health and Safety Administration's (OSHA's) method for measuring airborne asbestos mandated in 1972. This error was repeated, most notably, by the National Institute for Occupational Safety and Health (NIOSH) in, 1980 for talc mined in northern New York State (NYS) by RT Vanderbilt Company (RTV). Subsequent exposure studies of northern NYS talc conducted through the, 1980s and one study published after, 2000 relied on the conclusion that talc was an asbestos-containing material to infer a causal relationship between talc and mesothelioma. The present review included (1) publications concerning talc's cancer-causing potential issued by organizations concerned with occupational and public health; (2) talc exposure studies and animal and cellular studies of RTV talc; (3) mesothelioma rates in northern NYS; and (4) mesothelioma mortality among RTV mining employees. The review indicated that failure to correctly identify the mineral characteristics of talc resulted in misleading reports concerning the carcinogenic potential of talc. However, the collective data from animal and cellular studies, mesothelioma rates in northern NYS, exposure studies, and a mortality analysis of RTV mining employees do not support a causal relationship between RTV talc and mesothelioma. This conclusion is applicable to all mineral components in RTV talc and to other industrial-grade talcs and mineral aggregates with the same components.

In plain English

This single-author review examined whether industrial-grade talc mined by RT Vanderbilt Company (RTV) in northern New York State causes mesothelioma. The author argued that this talc had been wrongly classed as asbestos-containing. It is mostly amphibole cleavage fragments, platy talc, serpentine minerals and fibrous talc, with minor transitional fibers. In state cancer registry data for Jefferson and St. Lawrence Counties, there were 42 male and 11 female mesothelioma deaths in 1990–2004. These rates were not statistically different from US incidence rates, and male rates declined. For RTV workers, the author estimated 379 deaths after 1989 from age and employment records, without a formal vital-status update. RTV received notice of five mesotheliomas; a physician's review found enough diagnostic information to support the diagnosis in only one. Counting that one case against an estimated 604 total cohort deaths, the author put the proportional mortality ratio at 0.17%, about ten times lower than at amphibole asbestos mines. The author concluded that the evidence was insufficient to infer that RTV talc causes mesothelioma. RTV partly funded the work; the author has been its consultant and expert witness.

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: Critical review of agency evaluations and published studies, plus the author's own analysis of New York State Cancer Registry mesothelioma mortality data and an estimated update of an RTV worker cohort. The author declares partial funding from RT Vanderbilt and work as its consultant and designated expert witness.
• Who was studied: Two groups. (1) Residents of Jefferson and St. Lawrence Counties, northern New York State, in registry mesothelioma death data for 1990–2004. (2) RTV talc mine workers at Gouverneur, St. Lawrence County: 809 workers employed at least 1 day from 1948 to 1989 (from Honda et al.), plus 117 hired after 1989. Age and employment data were available for 630 of the 684 employees alive in 1990.
• Exposure: Industrial-grade talc mined by RTV in the Gouverneur district, described as, in order of prevalence, amphibole cleavage fragments, platy talc, serpentine minerals, talc in fibrous form, and a minor presence of transitional fibers. The author states this talc does not contain asbestos.
• Main results:
  • Jefferson and St. Lawrence Counties combined, 1990–2004: 42 male and 11 female mesothelioma deaths. The age-adjusted mortality rates for males and females were not statistically different from US incidence rates estimated from SEER data.
  • Males in the two counties: rates declined from the late 1990s (combined rate 4.0 per 100,000 in 1990–1994, 3.9 in 1995–1999, 1.5 in 2000–2004). The author attributed the male pattern most likely to occupational exposure to commercial amphibole asbestos.
  • Females in the two counties: the author judged the rate constant and not statistically different from the US SEER-based rate over the 15 years.
  • RTV worker cohort: using population survival statistics, the author estimated that 251 employees were alive in 2008 and that there were 379 additional deaths, for an estimated total of 604 deaths in the cohort alive in 1950 who worked at least 1 day.
  • Among the estimated 379 additional deaths, RTV received notice of five mesotheliomas alleging RTV talc as a cause. A physician's review found that only one notice had enough diagnostic information to support a mesothelioma diagnosis, and found no evidence that any of the five were due to RTV talc.
  • With one confirmed mesothelioma case among RTV talc workers, set against the estimated 604 total cohort deaths (Table 2), the author estimated a proportional mortality ratio of 0.17%. The author states this is an order of magnitude smaller than at mines where amphibole asbestos exposure has been associated with mesothelioma. The US background figure cited is approximately 0.035%.
• The authors' conclusion: The author concluded that the scientific evidence is insufficient to infer a causal relationship between RTV talc and mesothelioma. The author also stated that this applies to all mineral components of RTV talc and to other industrial-grade talcs and mineral aggregates with the same components.
• Limitations the authors state:
  • No formal study has updated the vital status of the RTV worker cohort since 1989; the post-1989 deaths were estimated.
  • The review dealt mainly with RTV talc from northern New York State. The author noted this could appear to be a limitation, but argued the results still apply to other talcs with the same components.
  • The state registry does not publish exact counts of 5 or fewer, so several female counts are reported only as fewer than 6.

Topics

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

Medical terms in this study, explained in our Lexicon: Talc, Mesothelioma, Amphibole Group, Cleavage Fragment, Serpentine Group, Transitional Fibers, Asbestos-Containing Material (ACM), OSHA.

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• Occupational exposures to cosmetic talc and risk of mesothelioma: an updated pooled cohort and statistical power analysis with consideration of latency period — G.M. Marsh, A.M. Ierardi, et al. (2019)
• An evaluation of the risks of lung cancer and mesothelioma from exposure to amphibole cleavage fragments — J.F. Gamble, G.W. Gibbs (2008)
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