A simple dispenser for generating dust clouds from standard reference samples of asbestos

Our plain-English summary of A simple dispenser for generating dust clouds from standard reference samples of asbestos, by V. Timbrell, A.W. Hyett, J.W. Skidmore (The Annals of Occupational Hygiene, 1968).

The study

• Authors: V. Timbrell, A.W. Hyett, J.W. Skidmore
• Journal: The Annals of Occupational Hygiene
• Published: 1968;11(4):273-81
• Cited by: 17 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This dispenser has been developed for the economical generation of dust clouds from the five UICC reference samples of asbestos which are now available for distribution to research centres. The consumption rate of any sample to produce a mass concentration of 12 mg/m³ of respirable dust in an airflow of 20 m³/hr is only 1 g/hr. An extended trial has demonstrated the reliability of the dispenser.

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

In plain English

This paper described a laboratory device for turning the five UICC standard reference samples of asbestos into airborne dust for animal inhalation experiments. The samples were amosite, anthophyllite, Canadian chrysotile, Rhodesian chrysotile and crocidolite. The device was built from a modified household coffee grinder and a plastic syringe. The paper reported no health outcomes. The authors gave settings for each sample and data from an experiment in which rats in five chambers were exposed about 7 hours a day, 5 days a week, for 12 weeks. Across 60 seven-hour readings per sample, mean concentrations of respirable dust ranged from 12.1 mg per cubic metre (Canadian chrysotile) to 13.2 (anthophyllite), with standard deviations from 1.81 to 2.68. Respirable dust made up 67% to 87% of the dust by mass, depending on the sample. The dispensers used 0.6 to 1.0 g of sample per hour. Five dispensers ran 1000 hours each without failure. Undispersed clumps of fibre remained in the dust clouds and were largest and most numerous with chrysotile. The authors judged the results favourable by the normal standard of inhalation experiments.

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 laboratory apparatus (a dust dispenser), with performance data from a rat inhalation experiment
• Who was studied: Laboratory rats in five inhalation chambers at the Medical Research Council Pneumoconiosis Research Unit, Penarth, UK. The number of rats is not stated, and no health results for the rats are reported.
• Exposure: Dust clouds generated from the five UICC reference samples: amosite (South Africa), anthophyllite (Finland), chrysotile (Canada), chrysotile (Rhodesia) and crocidolite (South Africa)
• Main results:
  • Rats were exposed for about 7 hours a day, 5 days a week, for 12 weeks.
  • Mean of 60 seven-hour average mass concentrations of respirable dust, with standard deviations in brackets: amosite 12.4 (2.68), anthophyllite 13.2 (2.2), Canadian chrysotile 12.1 (2.35), Rhodesian chrysotile 12.3 (2.48), crocidolite 12.6 (1.81) mg per cubic metre
  • Respirable percentage of the dust by mass: amosite 76, anthophyllite 83, Canadian chrysotile 74, Rhodesian chrysotile 67, crocidolite 87
  • Sample consumption rates ranged from 0.6 to 1.0 g per hour.
  • Five dispensers were each used for 1000 hours with no failure.
  • Undispersed flocks were largest and most numerous in the chrysotile clouds. Dust clouds could hardly be seen in the amphibole chambers, while the chrysotile chambers looked like falling snow. The authors stated that most flocks were not respirable.
• The authors' conclusion: The authors judged the concentration results favourable by the normal standard of inhalation experiments. They stated that the low consumption rates would allow a great amount of experimental work with the reference samples.
• Limitations the authors state:
  • Complete disintegration of all flocks was difficult, and some flocks occurred in the dust clouds.
  • Incomplete disintegration made consumption rates higher than would otherwise be necessary.
  • The low torque of the coffee-grinder motors caused small speed differences between dispensers and small speed fluctuations. The authors stated these were later eliminated by substituting other motors.
  • Clouds set to equal mass of respirable dust must be expected to differ on other measures, such as number concentration.

Topics

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

Related studies

• The Konimiser--a dispenser for the continuous generation of dust clouds from milligram quantities of asbestos — R.F. Hounam (1971)
• Quantitative assessment of inorganic fibrous particulates in dust samples with an analytical transmission electron microscope — F.D. Pooley, N.J. Clark (1979)
• The early effects of chrysotile asbestos dust on the rat lung — P.F. Holt, J. Mills, et al. (1964)
• UICC standard reference samples of asbestos — V. Timbrell, J.C. Gibson, et al. (1968)
• Human exposure to asbestos: dust controls and standards. The inhalation of fibrous dusts — V. Timbrell (1965)
• Void-counting in assessing membrane filter samples of asbestos fibre — M.D. Attfield, S.T. Beckett (1983)

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