The effect of amostie and chrysotile asbestos on the clearance of TiO2 particles from the lung

Our plain-English summary of The effect of amostie and chrysotile asbestos on the clearance of TiO2 particles from the lung, by J. Ferin, L.J. Leach (Environmental Research, 1976).

The study

• Authors: J. Ferin, L.J. Leach
• Journal: Environmental Research
• Published: 1976;12(2):250-4
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

It is well known that the pulmonary system encompasses pathways by which foreign materials can be removed from the body. The defense mechanisms involved in this removal, are presently being examined closely in order to more fully understand the complex interactions between the lung parenchyma and airborne agents. In the experiments described here, techniques have been developed to assess the effects of air pollutants on the alveolar clearance pattern of inert particles deposited in the lungs of laboratory animals. Amosite or chrysotile asbestos exposures, relatively short in duration (1-3 hours) and high in concentration (- 10 mg/m3) depressed the alveolar clearance of titanic oxide (TiO2) particles in rats. This effect was not observed when asbestos air concentrations were reduced to about 10X the Threshold Limit Value (TLV) estimated to be - 0.1 mg/m3. Extending the postexposure observation period and the number of exposures to 11 or 22 a suppressive effect on TiO2 clearance was seen. How important this late effect is can not be determined at this time. However, the effect of high concentrations of amosite or chrysotile at exposures lasting only a short time should be considered with concern.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This was a laboratory experiment in male hooded Long-Evans rats at the University of Rochester. The authors tested whether inhaling amosite or Canadian chrysotile asbestos changed how well the lungs cleared inert titanium dioxide (TiO2) particles. Rats breathed asbestos at about 1 to 14 mg/m3, for periods from 1 hour to 22 days. They then inhaled TiO2, and groups of about ten were killed at set days afterward. In two amosite experiments at 11 to 14 mg/m3 lasting 1 or 3 hours, TiO2 retention was significantly raised. The authors read this as clearance suppressed by about 54% and about 37%. At 5 mg/m3, suppression was about 50%. At about 1 mg/m3 with three or five exposures, no effect was seen. With 11 or 22 exposures at 1 mg/m3, a significant difference appeared at Day 130 but not Day 25. The authors judged that this pointed more toward no effect, and said its importance could not be determined. Three chrysotile experiments showed a similar pattern. The authors concluded that short exposures at high concentrations should be considered with concern.

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: Animal inhalation experiment in rats, measuring lung clearance of inhaled titanium dioxide particles after asbestos exposure, compared with control rats
• Who was studied: Male hooded rats of Long-Evans descent weighing about 250 g at the start, in groups of about ten, at the University of Rochester, Rochester, New York (article received December 1975)
• Exposure: Inhaled amosite or Canadian chrysotile (UICC Standard Reference Asbestos Samples) at about 1 to 14 mg/m3 for 1 hour to 22 days. The longest amosite exposures were 11 or 22 exposures of 5 and a half hours each. This was followed by a test inhalation of titanium dioxide, usually for 7 hours at about 15 mg/m3.
• Main results:
  • Amosite at high concentration (11 to 14 mg/m3) for 1 or 3 hours: titanium dioxide retention was significantly elevated compared with control and special control groups, indicating clearance suppression of about 54% in Experiment 1 and about 37% in Experiment 2
  • Amosite at low concentration (0.9 to 1.0 mg/m3) with three or five exposures: no effect on titanium dioxide retention was observed
  • Amosite at medium concentration (5 mg/m3, Experiment 6): a significant difference in titanium dioxide retention at Days 25 and 130, indicating clearance suppression of about 50%. Low concentration (Experiment 5) showed no effect at Day 25 or Day 130.
  • Amosite at 1 mg/m3 with 11 or 22 exposures: no effect at Day 25, but a statistically significant difference at Day 130. The authors judged that these results pointed more toward no effect than toward clearance suppression.
  • Chrysotile (three experiments): high concentrations (about 15 mg/m3) lasting a few hours gave elevated titanium dioxide retention at Day 25. One experiment at about 1 mg/m3, five exposures of 5 and a half hours, showed no sign of clearance suppression.
• The authors' conclusion: The authors concluded that short exposures of hours affected alveolar clearance when the concentration was above 5 mg/m3. They said the effect of high concentrations of asbestos, even at short exposures, should be considered with concern.
• Limitations the authors state:
  • The effective air concentration of chrysotile may differ from that of amosite because chrysotile had a much lower respirable fraction (about 23% versus about 72%)
  • The absolute analytical values in the extended low-concentration experiments were low
  • The importance of the late effect seen at Day 130 could not be determined

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Parenchyma, Amosite, Asbestos Exposure, Threshold Limit Value (TLV).

Related studies

• A biopersistence study following exposure to chrysotile asbestos alone or in combination with fine particles — D.M. Bernstein, K. Donaldson, et al. (2008)
• Deposition, clearance, and translocation of chrysotile asbestos from peripheral and central regions of the rat lung — P.G. Coin, V.L. Roggli, et al. (1992)
• A comparative study of the clearance of respirable para-aramid, chrysotile and glass fibres from rat lungs — A. Searl (1997)
• Lung proliferative and clearance responses to inhaled para-aramid RFP in exposed hamsters and rats: comparisons with chrysotile asbestos fibers — D.B. Warheit, S.I. Snajdr, et al. (1997)
• Deposition pattern and clearance pathways of inhaled chrysotile asbestos — A.R. Brody, L.H. Hill (1981)
• Deposition and clearance of chrysotile asbestos — A. Churg (1994)

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