Fibrous dust particles and ferruginous bodies. Methods for quantitating them and some results from the lungs of city dwellers

Our plain-English summary of Fibrous dust particles and ferruginous bodies. Methods for quantitating them and some results from the lungs of city dwellers, by P. Gross, J. Tuma, T.P. DeTreville (Archives of Environmental Health, 1970).

The study

• Authors: P. Gross, J. Tuma, T.P. DeTreville
• Journal: Archives of Environmental Health
• Published: 1970;21(1):38-46
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy.

In plain English

This 1970 paper described laboratory methods for counting and measuring uncoated ("naked") fibers and ferruginous (coated) bodies in human lungs. It reported results from the autopsy lungs of ten people: seven city dwellers, two long-time workers at a fibrous glass factory, and one worker at an asbestos products plant. Lung tissue was dissolved with chemicals, and the fibers were counted, photographed and measured. The text reported 15,100 to 66,400 naked fibers per gram of dry lung. The table listed a higher figure, 84.8 thousand, for the asbestos products worker. Fibers made up 0.01% to 0.47% of the lung dust by weight. Mean fiber diameters were mostly 1.9 to 2.2 microns. Some ferruginous bodies appeared to have formed on plates resembling talc crystals. The paper did not identify which fibers were asbestos and left that for a future paper. The authors concluded that their findings seemed to confirm earlier conclusions that respirable fibrous dust particles are everywhere. They said the method probably undercounts fibers. One reason is that fibers much thinner than 1 micron were not counted.

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: Laboratory methods-development study, applied to autopsy lungs from a small series of individuals
• Who was studied: Lungs of 10 people: seven city dwellers (selected only by sex; four women and three men in the table, aged 46 to 81), two long-time employees of a fibrous glass factory, and one employee of an asbestos products factory. The lungs were provided by pathologists in Pittsburgh and Newark, Ohio, and by the medical director of Johns-Manville Co.
• Exposure: Inhaled fibrous dust in general city dwellers. Working-lifetime exposure to dust in a fibrous glass factory (two men) and long-time work in an asbestos products factory (one person). The fiber types in the lungs were not identified in this paper.
• Main results:
  • The amount of dust per gram of dried lung varied up to fourfold between lungs.
  • The text reported naked fibers ranging from 15,100 to 66,400 per gram of dry lung. The table lists 84.8 thousand per gram for the asbestos products worker (case C).
  • Naked fibers made up 0.01% to 0.47% of the total weight of the lung dust.
  • Mean fiber diameter ranged from 1.9 to 2.2 microns, with one lung at 2.8 microns. Generally 3% to 9% of fibers were thicker than 3 microns; in one lung 30% were.
  • In most lungs, about two thirds of the fibers were 5 to 25 microns long, and only 3% to 9% were longer than 50 microns. Rare gigantic fibers, judged probably man-made glass, were excluded from the counts.
  • Ferruginous bodies per milligram of dust varied from 11 to 440 (text). The number of naked fibers per ferruginous body varied from 5 to 211.
  • In the table, the asbestos products worker (case C) had 73,000 ferruginous bodies per gram of dry lung. The other lungs with counts ranged from 160 to 3,927 per gram.
  • Some ferruginous bodies were irregular and appeared to have formed on fractured crystalline plates consistent with talc. The authors suggested some city dwellers may have been exposed to talc dust.
  • The authors estimated that some lungs contained at least 3 to 4 million fibers.
  • Duplicate counts differed by 1% to 15% (mean 9%). In tests with glass fibers added to rat liver, the error in estimating the weight of added glass was as high as 27%.
• The authors' conclusion: The authors concluded that their findings seemed to confirm the earlier conclusions of Cralley et al that respirable fibrous dust particles are ubiquitous. They also suggested that the often bizarre shapes of the ferruginous bodies point to exposure to fibrous dust different from the usual type of asbestos.
• Limitations the authors state:
  • Most of the method's deficiencies tend to give results lower than the probable actual values.
  • Chrysotile is more soluble than other forms of asbestos, and it is not known how much of it may disappear during the long formamide digestion.
  • Fibers substantially thinner than 1 micron are not counted, and some of the thinnest fibers and some shorter fibers may be overlooked.
  • Counts were made from a very small portion of the whole sample (1/300 to 1/2,500).
  • Material may be lost during centrifugation and washing.
  • The authors did not know how much lung tissue had been removed by the prosectors, so totals per pair of lungs could not be determined exactly.
  • Ferruginous bodies were not counted in two lungs because all of their tissue had been digested with formamide, which destroys them.
  • In the glass-fiber accuracy check, the close agreement with the actual weight was considered due to chance.

Topics

Medical terms in this study, explained in our Lexicon: Ferruginous Bodies.

Related studies

• Pulmonary ferruginous bodies in city dwellers. A study of their central fiber — P. Gross, R.T. DeTreville, et al. (1969)
• Dust particles in lung sections. Some notes on methods of their visualization — P. Gross, E.B. Tolker (1966)
• Ferruginous (asbestos) bodies in the lungs of rural dwellers, urban dwellers, and patients with pulmonary neoplasms — P.H. Breedin, D.H. Buss (1976)
• Ferruginous bodies and the histologic evaluation of dust exposure — E. Crouch, A. Churg (1984)
• Ferruginous bodies: implications in the mechanism of fiber and particle toxicity — A.J. Ghio, A. Churg, et al. (2004)
• Some biological properties of respirable iron ore dust — D. Keast, N.P. Sheppard, et al. (1987)

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