The International Agency for Research on Cancer (IARC) assessed the carcinogenicity of metals, arsenic, dust, and fibers previously classified as “carcinogenic to humans” (Group 1) and identified additional tumor sites and mechanisms of carcinogenesis.
LANCET SUMMARY - WIDESPREAD EXPOSURE & DISEASE
It reported that 125 million workers continue to be exposed to asbestos. Lancet reports:
"Globally, an estimated 125 million people are still exposed to asbestos in the workplace. Although asbestos has been banned or restricted in most of the industrialized world, its use is increasing in parts of Asia, South America, and the former Soviet Union. Naturally occurring sources of asbestos, its use in brake linings, and the deterioration of asbestos-containing products all contribute to environmental exposure worldwide. Exposure may also come from fibers carried home on the clothing of asbestos workers.
"Epidemiological evidence has increasingly shown an association of all forms of asbestos (chrysotile, crocidolite, amosite, tremolite, actinolite, and anthophyllite) with an increased risk of lung cancer and mesothelioma. Although the potency differences with respect to lung cancer or mesothelioma for fibers of various types and dimensions are debated, the fundamental conclusion is that all forms of asbestos are “carcinogenic to humans” (Group 1). Mineral substances (e.g., talc or vermiculite) that contain asbestos should also be regarded as “carcinogenic to humans.”
"Sufficient evidence is now available to show that asbestos also causes cancer of the larynx and of the ovary. A meta-analysis of cohort studies reported a relative risk of cancer of the larynx of 1·4 (95% CI 1·2—1·6) for “any” exposure to asbestos. With different exposure metrics, the relative risk for “high” exposure versus “none” was at least 2·0 (1·6—2·5).5 Cohort studies of women who were heavily exposed to asbestos in the workplace consistently report increased ovarian cancer risks, as in a study of women in the UK who manufactured gas masks during World War II.6 Studies suggest that asbestos can accumulate in the ovaries of women who are exposed to it.
"The Working Group classified the evidence for an association between asbestos and colorectal cancer as “limited”, although members were evenly divided as to whether the evidence was strong enough to warrant classification as “sufficient.” Further, there is “limited” evidence in humans for cancers of the pharynx and of the stomach.
The Lancet Oncology, Volume 10, Issue 5, Pages 453 - 454, May 2009, DOI:https://doi.org/10.1016/S1470-2045(09)70134-2
OCCUPATIONAL EXPOSURE
The IRAC report concluded:
"1.5.2 Occupational exposure Asbestos has been in widespread commercial use for over 100 years (USGS, 2001).
"Globally, each year, an estimated 125 million people are occupationally exposed to asbestos (WHO, 2006). Exposure by inhalation, and to a lesser extent ingestion, occurs in the mining and milling of asbestos (or other minerals contaminated with asbestos), the manufacturing or use of products containing asbestos, construction, automotive industry, the asbestos-abatement industry (including the transport and disposal of asbestos-containing wastes).
"Estimates of the number of workers potentially exposed to asbestos in the USA have been reported by the National Institute of Occupational Safety and Health (NIOSH), by the Occupational Safety and Health Administration (OSHA), and the Mine Safety and Health Administration (MSHA). OSHA estimated in 1990 that about 568000 workers in production and services industries and 114000 in construction industries may have been exposed to asbestos in the workplace (OSHA, 1990).
"Based on mine employment data from 2002, NIOSH estimated that 44000 miners and other mine workers may have been exposed to asbestos during the mining of asbestos and some mineral commodities in which asbestos may have been a potential contaminant (NIOSH, 2002b).
"More recently, OSHA has estimated that 1.3 million employees in construction and general industry face significant asbestos exposure on the job (OSHA, 2008).
"In addition to evidence from OSHA and MSHA that indicates a reduction in occupational exposures in the USA over the past several decades, other information compiled on workplace exposures to asbestos indicates that the nature of occupational exposures to asbestos has changed (Rice & Heineman, 2003).
"Once dominated by chronic exposures in manufacturing processes such as textile mills, friction-product manufacturing, and cement pipe fabrication, current occupational exposures to asbestos primarily occur during maintenance activities or remediation of buildings that contain asbestos.
TALC CONTAINING ASBESTIFORM FIBERS
“Talc particles are normally plate-like. These particles, when viewed on edge under the microscope in bulk samples or on air filters, may appear to be fibres, and have been misidentified as such. Talc may also form true mineral fibres that are asbestiform in habit. In some talc deposits, tremolite, anthophyllite, and actinolite may occur. Talc containing asbestiform fibres is a term that has been used inconsistently in the literature. In some contexts, it applies to talc containing asbestiform fibres of talc or talc intergrown on a nanoscale with other minerals, usually anthophyllite. In other contexts, the term asbestiform talc has erroneously been used for talc products that contain asbestos.
CANCER
Pleural and peritoneal mesotheliomas were reported to be associated with occupational exposures to crocidolite, amosite, and chrysotile.
Gastrointestinal tract cancers were reported to have been demonstrated in groups occupationally exposed to amosite, chrysotile, or mixed fibers containing chrysotile.
An excess of larynx cancer in occupationally exposed individuals was also noted.
Mesothelioma may occur among individuals living in neighborhoods of asbestos factories and crocidolite mines and in persons living with asbestos workers.
A causal association between asbestos exposure and lung cancer is generally well recognized.
CONCLUSION
"There is sufficient evidence in humans for the carcinogenicity of all forms of asbestos (chrysotile, crocidolite, amosite, tremolite, actinolite, and anthophyllite).
"Asbestos causes mesothelioma and cancer of the lung, larynx, and ovary.
"Also, positive associations have been observed between exposure to all forms of asbestos and cancer of the pharynx, stomach, and colorectum. For cancer of the colorectum, the Working Group was evenly divided as to whether the evidence was strong enough to warrant classification as sufficient.
"There is sufficient evidence in experimental animals for the carcinogenicity of all forms of asbestos (chrysotile, crocidolite, amosite, tremolite, actinolite and anthophyllite).
"All forms of asbestos (chrysotile, crocidolite, amosite, tremolite, actinolite and anthophyllite) are carcinogenic to humans (Group 1).
Arsenic, Metals, Fibres, and Dusts IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 100C (2012)
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The author, Jon L. Gelman, practices law in Wayne, NJ. He is the author of NJ Workers’ Compensation Law (Thomson-Reuters) and co-author of the national treatise Modern Workers’ Compensation Law (Thomson-Reuters). For over five decades, the Law Offices of Jon L Gelman 1.973.696.7900 jon@gelmans.com have represented injured workers and their families who have suffered occupational accidents and illnesses.
Recommended Citation: Gelman, Jon L., IARC To Review Human Carcinogens-metals, arsenic, dusts & fibers (asbestos), www.gelmans.com (2020), https://www.gelmans.com/ReadingRoom/tabid/65/ArtMID/1482/ArticleID/3/preview/true/Default.aspx
© 2009-2022 Jon L Gelman. All rights reserved.
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