Interspecies Comparisons of the Toxicity of Asbestos and Synthetic Vitreous Fibers: A Weight-of-the-Evidence Approach

Emission of airborne fibers from mechanically impacted asbestos-cement sheets and concentration of fibrous aerosol in the home environment in Upper Silesia, Poland

“…There are three essential factors that are required to develop such disease [6]: adequate dose, dimensions of the fibers in the alveolar region, and fiber biopersistence. Other fiber properties, such as presence of iron or other transition metals on fibers, ability of fibers to generate free radicals [7,8], and the ability of fibers to interact with and alter biologically relevant molecules, as well as, the ability of fibers to produce reactive oxygen/nitrogen species (ROS) may also be determinants of fiber toxicity [6], especially among biopersistent fibers. Fibers may catalyze the generation of oxidants directly from molecular oxygen or indirectly from reactive oxygen and nitrogen species released by inflammatory cells recruited to the lungs or pleura [9].…”

“…Typically, it is assumed that the most hazardous fibers are those longer than 5 m and of diameter up to 3-4 m [10]. It is possible that the physical form of a fiber is even more important than its chemical composition [6,11]. On the other hand, it is not fully understood whether the health impact is due to toxic compounds absorbed on the fibers.…”

Classification of man-made vitreous fibers: Comments on the revaluation by an IARC working group

“…As such, they gained superior weight for the evaluation of MMVF for the IARC working group in 2001. In the following, we will examine whether the published data support the preference given to recent chronic inhalation studies with fibers and whether the arguments of Maxim and McConnell (2001) add confidence to such a procedure.…”

“…Muhle and Pott (2000) concluded that rat inhalation tests with MMVF are not sufficiently sensitive for reliable identification of carcinogenic fibers. According to Maxim and McConnell (2001), ''there is no reason to conclude that humans are more sensitive than rats with respect to the development of lung cancer'' after inhalation exposure.…”

“…In 2001, the IARC working group remarked that ''there is no general agreement on which of these routes of administration best predicts human cancer risk.'' No position was taken and only reference was made to the contrasting views of Muhle and Pott (2000) and of Maxim and McConnell (2001). Muhle and Pott (2000) concluded that rat inhalation tests with MMVF are not sufficiently sensitive for reliable identification of carcinogenic fibers.…”