Health effects of World Trade Center (WTC) Dust: An unprecedented disaster's inadequate risk management

Our plain-English summary of Health effects of World Trade Center (WTC) Dust: An unprecedented disaster's inadequate risk management, by M. Lippmann, M.D. Cohen, L.C. Chen (Critical Reviews in Toxicology, 2015).

The study

• Authors: M. Lippmann, M.D. Cohen, L.C. Chen
• Journal: Critical Reviews in Toxicology
• Published: 2015;45(6):492-530
• Type of article: Review
• Cited by: 97 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The World Trade Center (WTC) twin towers in New York City collapsed on 9/11/2001, converting much of the buildings' huge masses into dense dust clouds of particles that settled on the streets and within buildings throughout Lower Manhattan. About 80-90% of the settled WTC Dust, ranging in particle size from ∼2.5 μm upward, was a highly alkaline mixture of crushed concrete, gypsum, and synthetic vitreous fibers (SVFs) that was readily resuspendable by physical disturbance and low-velocity air currents. High concentrations of coarse and supercoarse WTC Dust were inhaled and deposited in the conductive airways in the head and lungs, and subsequently swallowed, causing both physical and chemical irritation to the respiratory and gastroesophageal epithelia. There were both acute and chronic adverse health effects in rescue/recovery workers; cleanup workers; residents; and office workers, especially in those lacking effective personal respiratory protective equipment. The numerous health effects in these people were not those associated with the monitored PM2.5 toxicants, which were present at low concentrations, that is, asbestos fibers, transition and heavy metals, polyaromatic hydrocarbons or PAHs, and dioxins. Attention was never directed at the very high concentrations of the larger-sized and highly alkaline WTC Dust particles that, in retrospect, contained the more likely causal toxicants. Unfortunately, the initial focus of the air quality monitoring and guidance on exposure prevention programs on low-concentration components was never revised. Public agencies need to be better prepared to provide reliable guidance to the public on more appropriate means of exposure assessment, risk assessment, and preventive measures.

In plain English

This was a review by three New York University authors. It covered published research on dust from the World Trade Center collapse on 11 September 2001: dust measurements, studies of exposed workers and residents, and animal and cell experiments. The authors reported that 80 to 90% of the settled dust was crushed concrete, gypsum and synthetic vitreous fibers, and that chrysotile asbestos made up 0.8 to 3.0%. They described the coarse dust as highly alkaline. Most outdoor air measurements of asbestos were at typical background levels. But in tests stirring up contaminated indoor surfaces in one damaged building, airborne respirable asbestos was 10 to 1,000 times higher than airborne asbestos in homes with damaged asbestos materials. The reviewed studies reported excess respiratory and gastroesophageal illness in exposed groups. Cancer was outside the review's scope. The authors concluded that these effects were most likely due to the alkaline concrete and gypsum combined with irritation from crushed synthetic fibers, not to monitored trace toxicants such as asbestos. They also concluded that agencies' monitoring and guidance had focused on the wrong components.

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: Review article (the authors call it a critical review) of published dust-characterization, epidemiological, clinical, animal and cell studies on World Trade Center dust
• Who was studied: Published studies of people exposed to World Trade Center dust in Lower Manhattan after 9/11/2001: rescue and recovery workers (including New York City firefighters and police), cleanup workers, residents, and office and school workers. The review also covered laboratory studies in rats, mice and human lung cells.
• Exposure: Dust from the collapse of the World Trade Center towers. Most of it was coarse and supercoarse particles of crushed concrete, gypsum and synthetic vitreous fibers. It also contained cellulose (9 to 20%) and chrysotile asbestos fibers (0.8 to 3.0%). The authors stated that chrysotile insulation was present only in the first 20 floors of the North Tower and that there were no amphibole asbestos fibers in either building.
• Main results:
  • About 1% of the settled dust was in the fine size range (under 2.5 micrometers). About 40% was between 10 and 53 micrometers, and 52 to 63% did not pass through a 53-micrometer screen.
  • Outdoor settled dust collected in the first few days had a pH of 9 to 11. Indoor dust had an even higher pH, and the fine fraction was nearly neutral.
  • In the EPA (2002) evaluation summarized by the review, most outdoor (outside-air) measurements of asbestos fiber counts were within typical background levels.
  • The review reported resuspension tests by the RJ Lee Group in a heavily damaged building near the towers. Respirable asbestos concentrations in the dust resuspended into the air were 10 to 1,000 times higher than airborne asbestos concentrations in homes with damaged asbestos-containing materials. They were 100 to 10,000 times higher than airborne concentrations in public buildings with damaged asbestos-containing materials.
  • The review summarized a study of 57 Lower Manhattan apartments and five comparison apartments. Airborne fibers were not detected above background. Bulk dust samples showed asbestos in 16% of the Lower Manhattan apartments and none in the comparison sites.
  • In the same RJ Lee Group tests, World Trade Center dust became airborne 10 to 10,000 times or more readily than ordinary office building surface dust.
  • Among 20,834 participants in the Mount Sinai responder monitoring program (Kim et al. 2012, as reviewed), lifetime asthma prevalence was 2.9% before 9/11, 12.8% in 2002 and 19.4% in 2007.
  • Among 12,079 New York City Fire Department rescue workers (Banauch et al. 2006, as reviewed), the drop in lung function (FEV1) in the year after 9/11 equaled 12 years of age-related decline.
• The authors' conclusion: The authors concluded that, to a reasonable degree of scientific certainty, exposure to World Trade Center dust is causally associated with increased risk of COPD, reactive airways dysfunction syndrome, interstitial and restrictive lung disease, chronic laryngitis/pharyngitis, chronic rhinosinusitis and upper digestive disorders including GERD. They judged these effects most likely due to the alkaline concrete and gypsum combined with physical irritation from crushed synthetic vitreous fibers, rather than to the monitored fine-particle toxicants such as asbestos. They also concluded that agencies never revised their initial monitoring focus.
• Limitations the authors state:
  • The authors stated that cancer, birth defects and cardiovascular effects were beyond the scope of the review.
  • The authors stated that they found no literature on the combined effects of alkaline dust and synthetic vitreous fibers, so their hypothesis remains untested.
  • The authors stated that the air monitoring gave too few PM10 samples and no total suspended particle samples to estimate exposure to the coarse dust.
  • The authors stated that there has been little supporting evidence from inhalation studies in laboratory animals.

Topics

Medical terms in this study, explained in our Lexicon: Vitreous.

Related studies

• Characterization of the dust/smoke aerosol that settled east of the World Trade Center (WTC) in lower Manhattan after the collapse of the WTC 11 September 2001 — P.J. Lioy, C.P. Weisel, et al. (2002)
• Health and environmental consequences of the world trade center disaster — P.J. Landrigan, P.J. Lioy, et al. (2004)
• 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)
• 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)
• Health consequences of the September 11 World Trade Center attacks: a review — J. Moline, R. Herbert, et al. (2006)

Browse more research in Critical Reviews in Toxicology, or return to medical research.