The intersecting worlds of cancer and litigation changed last week. Why ? The US government issued its 12th Report on Carcinogens. The report adds eight new substances to the lists, including "certain inhaled glass fibers." This is not landmark news – there have been decades of suspicion and argument that some glass fibers are carcinogens. But now the argument is stronger and more specific.
What is the RoC, as its known ? "The Report on Carcinogens (RoC) is a congressionally mandated, science-based, public health document that is prepared for the HHS Secretary by the National Toxicology Program. The report identifies agents, substances, mixtures, and exposure circumstances that are known or reasonably anticipated to cause cancer in humans." Here and here are summary NYT summary stories by Gardiner Harris.
What substances were added? "The industrial chemical formaldehyde and a botanical known as aristolochic acids are listed as known human carcinogens. Six other substances — captafol, cobalt-tungsten carbide (in powder or hard metal form), certain inhalable glass wool fibers, o-nitrotoluene, riddelliine, and styrene — are added as substances that are reasonably anticipated to be human carcinogens. With these additions, the 12th Report on Carcinogens now includes 240 listings."
For asbestos litigation, the RoC matters because it further pushes open the door to exploring non-asbestos fibers as causes of diseases, including mesothelioma, the so-called signature disease for asbestos inhalation. The report’s pertinent general statement is as follows:
"Certain inhalable glass wool fibers made the list based on experimental animal studies. Not all glass wool or man-made fibers were found to be carcinogenic. The specific glass wool fibers referred to in this report have been redefined from previous reports on carcinogens to include only those fibers that can enter the respiratory tract, are highly durable, and are biopersistent, meaning they remain in the lungs for long periods of time. Glass wool fibers generally fall into two categories for consumers: low-cost, general purpose fibers, and premium, special purpose fibers. The largest use of general purpose glass wool is for home and building insulation, which appears to be less durable and less biopersistent, and thus less likely to cause cancer in humans."
The RoC includes a "profile" for each substance. For the wool fibers, the profile is here. And, here’s a more specific statement from the profile:
"Insulation Glass Fibers
Types of insulation glass wool fibers tested in experimental animals included Owens-Corning glass wool, MMVF 10 and 10a (both of which represent the respirable fraction of Manville 901 glass fiber), MMVF 11 (the respirable fraction of CertainTeed B glass fiber), and unspecified glass wool fibers. Inhalation exposure of F344 rats to Owens-Corning FG insulation fiberglass with binder (4 to 6 μm in diameter and > 20 μm long) significantly increased the incidence of mononuclear-cell leukemia in rats (males and females combined). Glass-fiber-related pulmonary and tracheal-bronchial lymph-node lesions were observed but were less severe than for exposure to special-purpose fibers. As with the findings for Tempstran 100/475 glass fibers in this strain (discussed above), these findings were considered to be exposure-related (Mitchell et al. 1986, Moorman et al. 1988). Intraperitoneal injection of MMVF 11 glass fibers caused mesothelioma of the abdominal cavity in male and female Wistar rats (Roller et al. 1996, 1997), and intraperitoneal injection of MMVF 10 glass fibers increased tumor rates in male Wistar rats (Miller et al. 1999)."
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