An experimental approach to the evaluation of the biopersistence of respirable synthetic fibers and minerals

Our plain-English summary of An experimental approach to the evaluation of the biopersistence of respirable synthetic fibers and minerals, by D.M. Bernstein, R. Mast, R. Anderson, et al (Environmental Health Perspectives, 1994).

The study

• Authors: D.M. Bernstein, R. Mast, R. Anderson, T.W. Hesterberg, R. Musselman, O. Kamstrup, J. Hadley
• Journal: Environmental Health Perspectives
• Published: 1994;102 Suppl 5(Suppl 5):15-8
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The biopersistence of fibers and minerals in the respiratory tract is an important parameter in the toxicity of those materials. The biopersistence of respirable synthetic fibers and minerals in man can be most closely evaluated in an animal model. While acellular and in vitro systems are important for initial evaluation of solubility and durability, they cannot simulate the dynamics of inhalation deposition and clearance and the subsequent systemic reaction to fibers and minerals that occurs in the animal. To evaluate the biopersistence of synthetic fibers, male rats were exposed to a well defined rat respirable aerosol of man-made vitreous fibers (MMVF), 6 hr/day for 5 days. Following exposure, subgroups were sacrificed at intervals ranging from 1 hr to 52 weeks. Following sacrifice, the lungs were removed, weighed, and immediately frozen at 20 degrees C for subsequent digestion by low temperature plasma ashing. The number, size distribution, and chemical composition of the fibers in the aerosol and lung were determined. With this animal model the role of biopersistence in altering the geometry and clearance of fibers can be systematically evaluated. The model also can be applied for the evaluation of the biopersistence of nonfibrous minerals.

In plain English

This article described a rat method for measuring how long inhaled fibers stay in the lung ("biopersistence"). Groups of 10 young male Fischer 344 rats breathed, through the nose only, man-made vitreous fibers (MMVF) at 30 mg/m3 or crocidolite asbestos at 10 mg/m3 for 6 hours a day on 5 consecutive days. A control group breathed filtered air. Fibers were pre-selected to be under about 1 micrometre in diameter, the size rats can breathe deep into the lung. Rats were killed at times from 1 hour after the last exposure to 52 weeks after the first, and the number, size and chemistry of fibers were measured in the lungs of five rats per group per time point. The article said its results were reported in other papers. It noted that fiber concentration varied by less than 10% between exposure ports, and that the MMVF tested all appeared to clear similarly. The authors concluded the model was a precise way to routinely evaluate whether fibers remain intact in the rat lung. They noted that some fibers were wider than 1 micrometre.

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: Description of an animal (rat) inhalation model for measuring fiber biopersistence; a methods paper
• Who was studied: Groups of 10 weanling (100-150 g) male Fischer 344 rats, exposed at the Geneva facility of Research and Consulting Company Ltd. Rats were sacrificed at 1 hour, 1 day, 5 days and 4 weeks after the last exposure, and at 13, 26 and 52 weeks after the start of exposure. The lungs of five rats per group per time point were analysed for fibers.
• Exposure: Nose-only inhalation, 6 hours a day for 5 consecutive days, of man-made vitreous fibers (MMVF) at 30 mg/m3 or crocidolite asbestos at 10 mg/m3; a negative control group was exposed to filtered air
• Main results:
  • When the exposure system was tested before use, fiber concentration varied by less than 10% from one animal port to another
  • The authors stated that the MMVF tested all appeared to clear from the rat lung similarly (data not presented in this article)
• The authors' conclusion: The authors concluded that the rat inhalation model provides a precise method for routinely evaluating the potential for fibers to remain intact in the distal airways and alveolar regions of the rat lung
• Limitations the authors state:
  • The water-based selection process did not fully meet its aim: some of the fibers were wider than about 1 micrometre
  • The current design could not determine the length of the fibers that are rat respirable (under 1 micrometre in diameter), because length and diameter were not measured together for each fiber
  • Rats can inhale into the deep lung only fibers generally under about 1 micrometre in diameter, while humans can inhale fibers up to about 3 micrometres

Topics

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

Related studies

• Introduction: INSERM-IARC-CNRS workshop on biopersistence of respirable synthetic fibers and minerals — J. Bignon, R. Saracci, et al. (1994)
• Biopersistence of respirable synthetic fibers and minerals: point of view of the chest physician — P. De Vuyst (1994)
• Biopersistence of respirable synthetic fibers and minerals: the point of view of the epidemiologist — P. Boffetta (1994)
• In vitro assays to predict the pathogenicity of mineral fibers — B.T. Mossman, A.M. Sesko (1990)
• Relationship between lung biopersistence and biological effects of man-made vitreous fibers after chronic inhalation in rats — T.W. Hesterberg, W.C. Miiller, et al. (1994)
• Biopersistences of man-made vitreous fibers and crocidolite fibers in rat lungs following short-term exposures — R.P. Musselman, W.C. Miiller, et al. (1994)

Browse more research in Environmental Health Perspectives, or return to medical research.