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Man-made Insulator Unlikely to Pose Same Mesothelioma Risk as Asbestos

141534_sheet metal workerGerman scientists say a man-made insulating material called refractory ceramic fiber (RCF) is unlikely to raise the risk of lung cancer or mesothelioma in workers, despite the results of animal studies.

. Although some tests of the aluminum-silicate based material on animals have suggested that it may also cause cancer, human studies have found no proof.

Now, a new study conducted by researchers in the Institute of Molecular Pharmacology and Toxicology in Munich say RCF fibers probably do not raise the risk for lung cancer or mesothelioma. They base their conclusion on the fact that RCF fibers are similar in size and shape to rock wool fibers and are likely to have a similar level of toxicity. Rock wool or stone wool is used in thermal insulation, filtration, soundproofing and to help germinate plants.

“For rock wool, the IARC [International Agency for Research on Cancer] concluded that the epidemiological studies did not provide evidence of carcinogenicity,” reports primary author and professor of toxicology, Helmut  Greim. “Based on analogies with rock wool, it is reasonable to believe that increases in lung cancer and mesothelioma are unlikely to be found in the RCF-exposed cohort.”

Unfortunately, the report does not mean that people who have worked around RCF are in the clear. The product has sometimes been used in manufacturing plants where asbestos was also present and a study earlier this year found that simultaneous exposure to RCF can compound the mesothelioma risk from asbestos by four times.

The good news is that, according to the study’s authors, RCF producers are taking no chances when it comes to protecting workers from potential risks. Unlike many plants that covered up the risks of highly toxic asbestos, the authors say RCF manufacturers have developed a “product stewardship program” to measure and control fiber concentrations and to monitor the health of their workers.


Greim, H et al “Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers”, September 20, 2014, Inhalation Toxicology, Epub ahead of print

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