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Saturday, May 16, 2009

IARC To Review Human Carcinogens-metals, arsenic, dusts & fibers (asbestos)

The International Agency for Research on Cancer (IARC) has met to reassessthe carcinogenicity of metals, arsenic, dusts, and fibres previously classified as “carcinogenic to humans” (Group 1) and to identify additional tumour sites and mechanisms of carcinogenesis. 

It reported that 125 million workers continue to be exposed to asbestos in the workplace. Lancet reports:

"Globally, an estimated 125 million people are still exposed to asbestos in the workplace.2 Although asbestos has been banned or restricted in most of the industrialised world, its use is increasing in parts of Asia, South America, and the former Soviet Union.3Naturally occurring sources of asbestos, its use in brake linings, and deterioration of asbestos-containing products all contribute to environmental exposure worldwide. Exposure may also come from fibres carried home on the clothing of asbestos workers.4
"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 fibres of various types and dimensions are debated, the fundamental conclusion is that all forms of asbestos are “carcinogenic to humans” (Group 1). Mineral substances (eg, 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 risks of ovarian cancer, 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.7
"The Working Group classified the evidence for an association between asbestos and colorectal cancer as “limited”, although members were evenly divided as to whetherx 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

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