Visible dust and asbestos: what does it suggest regarding asbestos exposures?

• Main Author: Stephen E. Petty
• Format: Article
• Language: English
• Published: Hamilton Publishing, Inc.
• Series: The Journal of Scientific Practice and Integrity
• Online Access: http://jospi.scholasticahq.com/article/14496-visible-dust-and-asbestos-what-does-it-suggest-regarding-asbestos-exposures.pdf

Courts in asbestos litigation in the past decade have increasingly required quantitation of asbestos exposures beyond arguments that the exposures exceeded de minimis or background levels. Exposure levels for those in the past were often either not measured or minimally measured. Similar Exposure Groups (SEGs) methods can be considered, however i) the available data to be used for comparison may not well reflect the exposures of the individual of interest and ii) past data/standards were taken in units of million particles per cubic foot of air (mppcf) as opposed to fibers per cubic centimeter (f/cc).1 The purpose of this work was to research these two issues to determine if exposure to visible dust created from asbestos-containing materials (ACM) (>1% asbestos) likely exceeds recommended asbestos exposure limits. This was accomplished by posing and answering the following three questions regarding asbestos exposures: 1) Was the American Conference of Governmental Industrial Hygienists’ (ACGIH) 5 million particles per cubic foot (mppcf) of air threshold limit value, in effect for many years, a total dust standard? 2) Does the presence of visible dust indicate the presence of more than 5 mppcf of dust in the air? 3) Would the presence of visible asbestos-containing dust demonstrate a potential health hazard? The author conducted a review of the available literature to determine the answers to these questions. The author also extensively researched and analyzed the conversion factor or ratio between exposures in units of mppcf and f/cc. The results indicate that: i) the 5 mppcf asbestos standard was based on total dust, not just asbestos dust; ii) the presence of visible dust from ACM operations is likely greater than 5 mppcf; and iii) that the presence of visible asbestos-containing dust likely results in levels above the American Conference of Governmental Industrial Hygienists’ (ACGIH) and the Occupational Safety & Health Administration’s (OSHA) standards. These results have implications for individuals performing retrospective asbestos exposure analysis.