Asbestos exposures to truck drivers during World Trade Center cleanup operations

Our plain-English summary of Asbestos exposures to truck drivers during World Trade Center cleanup operations, by P.N. Breysse, D.L. Williams, J.B. Herbstman, et al (Journal of Occupational and Environmental Hygiene, 2005).

The study

• Authors: P.N. Breysse, D.L. Williams, J.B. Herbstman, J.M. Symons, S.N. Chillrud, J. Ross, S. Henshaw, K. Rees, M. Watson, A.S. Geyh
• Journal: Journal of Occupational and Environmental Hygiene
• Published: 2005;2(8):400-5
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This article presents results of asbestos air sampling conducted to assess the exposure to truck drivers working at the World Trade Center site. Sampling consisted of a combination of area and personal monitoring of 49 truck drivers and included optical and electron microscopic analyses. Three sampling periods were conducted: October 1-7, 2001, October 17-26, 2001, and April 13-23, 2002. Area sample locations were selected to estimate airborne concentrations around the perimeter of the site, on top of the pile, and in the pit. Air samples were collected using a 50-mm conductive cowl and a 25-mm mixed cellulose ester filter at flow rates ranging from 0.5-2 L/min. Samples were analyzed using a combination of phase contrast microscopy (PCM) NIOSH method 7400, transmission electron microscopy (TEM) NIOSH method 7402, and the direct method specified under the Asbestos Hazardous Emergency Response Act. Sample times and flow rates were adjusted to prevent overloading while maximizing sample volume. Personal sampling results suggest that asbestos fiber exposures to truck drivers at the site were low. Exposures based on TEM results generally ranged from less than detectable to 0.1 structures per cubic centimeter (s/cm(3)). TEM-based results further indicate that the majority of asbestos fibers were chrysotile and less than 5 microm in length. PCM-based estimates were generally higher than the TEM results. This is likely due to the counting of nonasbestos fibers. This conclusion is supported by the NIOSH 7402 TEM results, which did not detect asbestos fibers longer than 5 micro m. Area sample results were generally less than the personal results (except for the sample collected on top of the rubble pile) and decreased over the course of the cleanup. Our results show low airborne asbestos concentrations and a predominance of short fibers. Given these low concentrations, evidence of short fibers, and the short duration of the exposure (less than 10 months to complete the cleanup), it is likely that truck drivers working at the site are not at an increased risk for asbestos-related disease.

In plain English

This study measured airborne asbestos during the World Trade Center cleanup, focusing on truck drivers. Air was sampled from the breathing zone of 49 drivers and at fixed spots around the site, on the rubble pile and in the pit. Sampling took place October 1–7 and 17–26, 2001, and April 13–23, 2002. In personal samples analyzed by electron microscopy (the AHERA TEM method), median levels for each period ranged from 0.012 to 0.017 structures per cubic centimeter. All structures but one (an amosite) were chrysotile, and about 4% were longer than 5 micrometers. By light microscopy (PCM), median October levels were 0.01 to 0.04 fibers per cubic centimeter. One of 33 PCM samples exceeded the OSHA limit of 0.1. The highest area sample, 0.123 structures per cubic centimeter, came from the middle of the pile. Of 40 perimeter samples, 31 were below detection. Citing the low levels, mostly short fibers and a cleanup lasting under 10 months, the authors concluded that drivers were not expected to be at significant increased risk of asbestos-related disease.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Exposure assessment study using personal and area air sampling with optical and electron microscopy
• Who was studied: 49 volunteer truck drivers working at the World Trade Center cleanup site in New York: 34 monitored in October 2001 and all 15 drivers remaining at the site in April 2002, with 15 drivers monitored more than once. Area samples were also taken around the site perimeter, on the rubble pile and in the pit.
• Exposure: Airborne asbestos at the World Trade Center site during cleanup (October 1–7, 2001; October 17–26, 2001; April 13–23, 2002). Samples were analyzed by phase contrast microscopy (PCM, NIOSH Method 7400), transmission electron microscopy (TEM, NIOSH Method 7402) and the AHERA direct TEM method. The fibers identified were chrysotile, plus one amosite structure.
• Main results:
  • Personal samples, AHERA TEM: median levels for each of the three sampling periods ranged from 0.012 to 0.017 structures per cubic centimeter.
  • Personal samples, AHERA TEM: the highest individual sample was 0.10 structures per cubic centimeter, collected during the week of October 1, 2001.
  • Personal samples, AHERA TEM: all asbestos structures detected but one were chrysotile; the one exception was amosite (April 2002). Very few (4%) were longer than 5 micrometers.
  • NIOSH Method 7402 TEM analyses detected no OSHA-countable asbestos fibers, meaning no optically visible fibers longer than 5 micrometers.
  • Personal samples, PCM (October periods only): of 33 samples analyzed, median fiber levels ranged from 0.01 to 0.04 fibers per cubic centimeter. Only one sample exceeded the OSHA permissible exposure limit of 0.1 fibers per cubic centimeter.
  • PCM fiber levels were slightly higher than the AHERA TEM asbestos levels. The authors attributed this likely to PCM counting non-asbestos particles of fiber size.
  • Area samples: the highest result, 0.123 structures per cubic centimeter, came from six chrysotile structures in a 551-liter sample from the middle of the rubble pile.
  • Area samples around the site perimeter (not on the pile): 31 of 40 (78%) were below the limit of detection.
• The authors' conclusion: The authors concluded that, given the low airborne levels, the predominance of short fibers and the short duration of exposure (less than 10 months to complete the cleanup), truck drivers working at the site are not expected to be at significant increased risk for asbestos-related disease.
• Limitations the authors state:
  • Seventeen personal samples could not be analyzed because they were overloaded with particulate matter.
  • The highest personal sample was collected over only 3.33 hours because of a pump failure.
  • PCM results are difficult to interpret because other, non-asbestos fibrous materials may be present.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Air Sampling, Mixed Cellulose Ester Filter, phase contrast microscopy (PCM), NIOSH Method 7400, Transmission Electron Microscopy (TEM), NIOSH, Chrysotile.

Related studies

• Assessing truck driver exposure at the World Trade Center disaster site: personal and area monitoring for particulate matter and volatile organic compounds during October 2001 and April 2002 — A.S. Geyh, S. Chillrud, et al. (2005)
• The legacy of World Trade Center dust — J.M. Samet, A.S. Geyh, et al. (2007)
• Development of an exposure assessment method for epidemiological studies of New York State personnel who responded to the World Trade Center disaster — M.L. Herdt-Losavio, M.P. Mauer, et al. (2008)
• Occupational exposures during the World Trade Center disaster response — K.M. Wallingford, E.M. Snyder (2001)
• Chest CT scan findings in World Trade Center workers — R.E. de la Hoz, J. Weber, et al. (2019)
• Summary of the development of a signature for detection of residual dust from collapse of the World Trade Center buildings — H.A. Lowers, G.P. Meeker, et al. (2009)

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