Applying Definitions to Asbestos

The Journal of Toxicology and Environmental Health recently released a review of the definitions of asbestos, its health effects, and exposure levels. Because asbestos was a global commodity and used abundantly in dozens of industries, the research concerning this mineral is widespread and controversial. Though much knowledge has been gained involving the scientific, biological, and mineralogical structure of asbestos fibers, there is not any general consensus in the understanding of exposure-response relationships. Controversy arises from the variety of asbestos types, exposure levels, and associated diseases. Asbestos exposure attorneys are hopeful that considerable efforts will be made to explore past studies, develop new methodology, and more rigidly define asbestos-related diseases.

Firstly, the term ‘asbestos’ applies to several minerals, specifically to six minerals: chrysotile, crocidolite, amosite, anthophyllite tremolite, and actinolite. Federal regulations of asbestos apply to all six of these minerals. The International Agency for Research on Cancer notes that the inadequate definition of asbestos has resulted in classification confusion and lack of standardized operating definitions. Too often, the regulatory and mineralogical definitions contradict each other.

An array of literature exists on the mineralogy of asbestos and related minerals; however, these definitions often contradict or confuse the regulatory, medical, and industrial definitions. To be useful, the definition must be unchanging and interdisciplinary. Usually, asbestos minerals belong to two groups: serpentine, which refers to chrysotile, and amphibole, which refers to the other five types. The morphology of chrysotile asbestos dust particles is distinctive when compared with the amphibole mineral varieties. Mineralogical definitions, such as those just discussed, unlike regulatory or industrial specifications, are based on a scientific rather than an operational classification, but they have varied considerably over time.

These changes in mineral names far outpace the ability of the rulemaking and legislative processes in the United States and have caused considerable confusion and misunderstanding, as is evident in recent legal actions relating to asbestos contamination in Libby, Montana. Recent attempts at better and more comprehensive and comprehensible terminology regarding fibers has been developed in the “NIOSH Roadmap” of 2010.

Second, accurate and meaningful exposure measurement has been the bane of much asbestos science. This is due to the complexity of the exercise. One of the most common approaches in human studies is to ask those who may have been exposed–with or without disease–what jobs or other circumstances existed in which they may have been exposed. Once identified, those with exposure must be classified according to amount and duration, and then be quantified according to number of asbestos fibers remaining in the lungs.

Lastly, in relation to environmental or low-dose exposure, it is likely that the proportion of cases due to environmental exposures is likely to increase in coming years. It is important to understand that an environmental exposure is not always a low-level exposure. The degree of exposure will depend on other factors, particularly the degree to which the existing environmental source is disturbed by anthropogenic (e.g., construction, road building) or natural (e.g., weathering, landslide) events. For some diseases, the mineral type (mesothelioma) and/or fiber length (lung cancer) of present asbestos will also play an important role.

It is therefore vital that asbestos deposits that may provide human exposures be well characterized mineralogically using techniques that allow identification of fiber chemistry and dimensions. There is also a need to have a clear understanding of the exposure “pathways” and the extent to which these are likely to result in exposure under a variety of conditions over time for these deposits. What is now needed is a breakdown of the results to more specific and individual exposures and disease.

Old ships under repair or destruction (“ship-breaking”) could constitute a current source of exposure in U.S. shipyards, but we are unaware of details of such activities.
Generally, most current potential occupational asbestos exposure situations are thought to involve asbestos already installed in products, especially for buildings with asbestos-containing materials (ACM) that are undergoing asbestos abatement, extensive renovation, or demolition, and particularly in the construction industry.

An example of the scope of the ongoing potential problem is seen in the fact that in the U.S. Environmental Protection Agency Toxics Release Inventory, 57 industrial facilities (mostly waste-management companies) reported releasing or disposing of about 20.5 million pounds (9300 metric tons) of friable (readily crumbled) asbestos in 2001.

Mesothelioma lawyers at Pintas & Mullins Law Firm highlight the importance of correct, comprehensive statistical models for asbestos exposure risk. If you suspect asbestos exposure of any kind, or have developed a related illness, contact a skilled asbestos attorney today for a free legal consultation.

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