Evaluation of the size and type of free particulates collected from unused asbestos-containing brake components as related to potential for respirability

BACKGROUND: Chrysotile asbestos has found multiple applications in the production of friction products. At one point it comprised 40-50% of the composition of brake linings thus generating the potential for the development of asbestos related diseases in millions of workers involved in vehicle repairs. While some attention has been given to the health status of workers involved in the handling of worn components, little has been given to the potential for exposure during the handling and fitting of new (unused) components as replacement parts. METHODS: Unused brake linings or brake shoes with attached linings from four different sources were gently rinsed with prefiltered water that was then collected on filters for analysis by Analytical Transmission Electron Microscope. RESULTS: Large numbers of chrysotile asbestos containing structures, the majority of respirable size, were present in each sample. CONCLUSIONS: We conclude that any manipulation of new asbestos containing brake components would be expected to yield free dust containing chrysotile asbestos of respirable size. That the vast majority of these fibers and particulates would not be counted as regulated fibers rendering assessment of potential exposures in the work place, based on data of Permissible Exposure Limits or Regulated Fibers, questionable.     

Asbestos in brakes: exposure and risk of disease

Asbestos has been incorporated into friction products since the early 1900s. Epidemiological studies have been equivocal in their analysis of the incidence of disease among mechanics servicing brakes. Decomposition of asbestos occurs during the normal usage of the brake due to thermal decomposition into forsterite, although not all asbestos is so converted. Short fibers, below 5 microm in length, are also found in brake products. Several facts are discussed including the toxicity of the remaining asbestos fibers, short asbestos fibers, and the health implications of exposure to forsterite. Control methodologies, when used appropriately, have reduced exposure to asbestos during brake servicing, but have not been able to entirely eliminate exposure to asbestos, thus bring into question the controlled use of asbestos for friction product such as brakes. Even the so called "controlled" use of asbestos containing brakes poses a health risk to workers, users, and their families.     

Impact of Operating Time on Selected Tribological Properties of the Friction Material in the Brake Pads of Passenger Cars

Braking systems have a direct impact on the safety of road users. That is why it is crucial that the performance of brakes be dependable and faultless. Unfortunately, the operating conditions of brakes during their operating time are affected by many variables, which results in changes in their tribological properties. This article presents an attempt to develop a methodology for studying how the operating time affects the value of the coefficient of friction and the abrasive wear factor. The Taguchi method of process optimization was used to plan the experiment, which was based on tests using the ball-cratering method. The results clearly show that the degree of wear affects the properties of the friction material used in the production process of brakes.     

Asbestos Exposure Causes Mesothelioma,But Not This Asbestos Exposure: An Amicus Brief to the Michigan Supreme Court

Abstract

Manufacturers of asbestos brakes, supported by many manufacturing and insurance industry amicus curie, requested the Michigan Supreme Court to dismiss testimony of an expert regarding the ability of asbestos dust from brakes to cause mesothelioma as “Junk science.” Scientists are concerned with the sweeping and unequivocal claims that any conclusion that asbestos from brakes caused a signature asbestos-related disease in a particular person must be “Junk science.” The manufacturers' sweeping pronouncements are what veer from accepted, reliable mainstream scientific methods and conclusions. This article outlines the evidence supporting the conclusion that asbestos from brakes can and does cause mesothelioma, and describes the defendants' attempts to fabricate doubt about this conclusion.