Case report: Lung disease in World Trade Center responders exposed to dust and smoke: carbon nanotubes found in the lungs of World Trade Center patients and dust samples

Our plain-English summary of Case report: Lung disease in World Trade Center responders exposed to dust and smoke: carbon nanotubes found in the lungs of World Trade Center patients and dust samples, by M. Wu, R.E. Gordon, R. Herbert, et al (Environmental Health Perspectives, 2010).

The study

• Authors: M. Wu, R.E. Gordon, R. Herbert, M. Padilla, J. Moline, D. Mendelson, V. Litle, W.D. Travis, J. Gil
• Journal: Environmental Health Perspectives
• Published: 2010;118(4):499-504
• Cited by: 90 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Context: After the collapse of the World Trade Center (WTC) on 11 September 2001, a dense cloud of dust containing high levels of airborne pollutants covered Manhattan and parts of Brooklyn, New York. Between 60,000 and 70,000 responders were exposed. Many reported adverse health effects.

Case Presentation: In this report we describe clinical, pathologic, and mineralogic findings in seven previously healthy responders who were exposed to WTC dust on either 11 September or 12 September 2001, who developed severe respiratory impairment or unexplained radiologic findings and underwent video-assisted thoracoscopic surgical lung biopsy procedures at Mount Sinai Medical Center. WTC dust samples were also examined. We found that three of the seven responders had severe or moderate restrictive disease clinically. Histopathology showed interstitial lung disease consistent with small airways disease, bronchiolocentric parenchymal disease, and nonnecrotizing granulomatous condition. Tissue mineralogic analyses showed variable amounts of sheets of aluminum and magnesium silicates, chrysotile asbestos, calcium phosphate, and calcium sulfate. Small shards of glass containing mostly silica and magnesium were also found. Carbon nanotubes (CNT) of various sizes and lengths were noted. CNT were also identified in four of seven WTC dust samples.

Discussion: These findings confirm the previously reported association between WTC dust exposure and bronchiolar and interstitial lung disease. Long-term monitoring of responders will be needed to elucidate the full extent of this problem. The finding of CNT in both WTC dust and lung tissues is unexpected and requires further study.

In plain English

This case report described seven World Trade Center (WTC) responders in the Mount Sinai monitoring program. Their exposure to WTC dust and smoke began on 11 or 12 September 2001, and they later had surgical lung biopsies, one in 2005 and six in 2007. Three of the seven had severe or moderate restrictive lung disease. Small airways disease appeared in almost all biopsies. Carbon nanotubes were found in lung tissue from four patients, at 3,450 to 230,000 per gram, and in four of seven WTC dust samples. None were found in 60 comparison lung samples: 40 from asbestos-exposed construction workers and 20 from people with no asbestos or WTC exposure. Chrysotile asbestos was found in four of the seven patients, in amounts the authors called modestly higher than New York City background levels. Platy aluminum and magnesium silicates were also found. The authors concluded that WTC exposure may have contributed to the lung disease, but said it remains unclear whether any of these materials caused it. They noted that lung sampling can be biased and that toxic gases were not analyzed.

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: Case report (case series) of seven patients, with electron microscopy analysis of their lung biopsy tissue, of WTC dust samples, and of comparison lung samples
• Who was studied: Seven WTC responders enrolled in the Mount Sinai WTC Medical Monitoring and Treatment Program in New York. All had exposure beginning 11 or 12 September 2001 and underwent video-assisted thoracoscopic (VATS) lung biopsy, one in 2005 and six between 1 January and 31 October 2007. Also examined: 7 WTC dust samples, lung samples from 40 construction workers with asbestos exposure, and 20 background lung samples from people without asbestos or WTC exposure.
• Exposure: WTC dust and smoke, with exposure beginning on 11 or 12 September 2001. Lung tissue was analyzed for chrysotile asbestos, aluminum and magnesium silicates, calcium sulfate, and carbon nanotubes (CNT).
• Main results:
  • Three of the seven responders had severe or moderate restrictive lung disease on clinical testing.
  • Small airways disease was present in almost all of the seven biopsies, at different levels of severity.
  • Patient A's lung tissue contained silicates at 165,600/g and CNT at 110,400/g.
  • Patient B's lung tissue contained CNT at 3,450/g and silicates at 165,600/g. No asbestos fibers were found.
  • Patient C's lung tissue contained chrysotile asbestos at 36,800/g, silicates at 184,000/g, and CNT at 230,000/g.
  • Patient D's lung tissue contained CNT at 11,040/g, silicates at 27,600/g plus large amounts of calcium sulfate, and chrysotile asbestos at 5,520/g.
  • Patient E's lung tissue contained chrysotile asbestos at 110,400/g and silicates at 110,400/g.
  • Patient G's lung tissue contained magnesium silicate at 63,086/g and chrysotile asbestos at 11,829/g.
  • Patient F's lung tissue analysis showed no relevant mineral findings.
  • Chrysotile asbestos was found in four of the seven patients, in amounts the authors described as modestly higher than background asbestos levels in the New York City population.
  • CNT were found in three of the four patients with extensive interstitial/parenchymal abnormalities and in one of the two patients with small airway disease. None were found in the patient with nonnecrotizing granulomas.
  • All CNT seen were single-walled and of various lengths.
  • Four of the seven WTC dust samples contained CNT.
  • No CNT were found in the lungs of the 40 construction workers or in the 20 negative control samples.
  • Among the 40 asbestos-exposed construction workers, less than 10% had platy aluminum and magnesium silicates like those seen in the WTC patients. Where present, they were in small quantities (less than 1,000/g wet weight of lung).
• The authors' conclusion: The authors concluded that the interstitial lung disease seen on pathology, together with similar materials (including CNT and platy silicates) in most of the mineral samples, suggests that WTC exposure may have contributed to the development of lung disease. They also stated that it remains unclear whether any of these compounds caused the lung pathology.
• Limitations the authors state:
  • Mineral analysis of the lungs can be biased because of sampling variability within the lung itself.
  • The timing of the biopsies likely reflected when federal treatment funding became available, so the cases do not accurately show when disease began, and the authors did not try to describe incidence.
  • The analysis did not include toxic soluble gases, so the cause of the conditions cannot be fully determined.
  • It remains unclear whether any of the materials found caused the lung pathology.
  • Finding CNT in the lungs cannot be taken as evidence of WTC exposure, and their absence should not be taken as evidence of no exposure.
  • Small numbers of CNT have recently been found, at minimal concentrations, in control specimens from the New York, New Jersey and Connecticut area (unpublished data).

Topics

Medical terms in this study, explained in our Lexicon: Biopsy, Histopathology, Interstitial Lung Disease, Silicate, Chrysotile.

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