Comparative hazards of chrysotile asbestos and its substitutes: A European perspective

Our plain-English summary of Comparative hazards of chrysotile asbestos and its substitutes: A European perspective, by P.T. Harrison, L.S. Levy, G. Patrick, et al (Environmental Health Perspectives, 1999).

The study

• Authors: P.T. Harrison, L.S. Levy, G. Patrick, G.H. Pigott, L.L. Smith
• Journal: Environmental Health Perspectives
• Published: 1999;107(8):607-11
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Although the use of amphibole asbestos (crocidolite and amosite) has been banned in most European countries because of its known effects on the lung and pleura, chrysotile asbestos remains in use in a number of widely used products, notably asbestos cement and friction linings in vehicle brakes and clutches. A ban on chrysotile throughout the European Union for these remaining applications is currently under consideration, but this requires confidence in the safety of substitute materials. The main substitutes for the residual uses of chrysotile are p-aramid, polyvinyl alcohol (PVA), and cellulose fibers, and it is these materials that are evaluated here. Because it critically affects both exposure concentrations and deposition in the lung, diameter is a key determinant of the intrinsic hazard of a fiber; the propensity of a material to release fibers into the air is also important. It is generally accepted that to be pathogenic to the lung or pleura, fibers must be long, thin, and durable; fiber chemistry may also be significant. These basic principles are used in a pragmatic way to form a judgement on the relative safety of the substitute materials, taking into account what is known about their hazardous properties and also the potential for uncontrolled exposures during a lifetime of use (including disposal). We conclude that chrysotile asbestos is intrinsically more hazardous than p-aramid, PVA, or cellulose fibers and that its continued use in asbestos-cement products and friction materials is not justifiable in the face of available technically adequate substitutes.

In plain English

This 1999 commentary, written from a largely UK perspective, was not a new study. The authors said it was not a comprehensive review of all available data. It compared the hazards of chrysotile asbestos with the main substitutes used for its remaining uses in asbestos-cement products and friction materials: p-aramid, polyvinyl alcohol (PVA) and cellulose fibers. Drawing on other researchers' work, the authors treated fiber dose, size (especially diameter) and durability in the lung as the key factors. They judged that chrysotile can cause lung cancer and asbestosis, but that it is less clear whether chrysotile alone causes mesothelioma in humans. They judged that PVA fibers pose less risk than chrysotile, mainly because they are generally too large to reach the deep lung. They judged that aramid fibers have a reduced potential for exposure. They judged that cellulose is durable in the lung and should be investigated further. They noted that a full health and toxicologic data set for the substitutes was lacking. They concluded that continued use of chrysotile in asbestos-cement products and friction materials is not justifiable given available, technically adequate substitutes.

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: Commentary presenting the authors' reasoned scientific arguments and judgments, based on a case prepared for the UK Health and Safety Commission; not a comprehensive review and not an original study
• Who was studied: No study population. The paper addressed the main substitute fibers (p-aramid, PVA, cellulose) for the remaining uses of chrysotile, from a European perspective drawing largely on UK conditions
• Exposure: Chrysotile asbestos compared with p-aramid, PVA and cellulose fibers, in the remaining chrysotile applications: asbestos cement and friction materials
• Main results:
  • The authors treated dose, fiber dimension (especially diameter) and durability as the key factors in judging the hazards of the different fibers
  • Chrysotile: the authors judged that it can cause lung cancer and asbestosis, and that it is less clear whether chrysotile alone causes mesothelioma in humans
  • PVA fibers: judged to pose less risk than chrysotile, mainly because they are generally too large to be respirable and do not fibrillate (split lengthwise)
  • Aramid fibers: judged to have a reduced potential for exposure compared with chrysotile, because they are generally of large diameter
  • Cellulose fibers: judged to be durable in the lung, so the authors said their biological properties should be investigated further
• The authors' conclusion: The authors concluded that continued use of chrysotile in asbestos-cement products is not justifiable given available, technically adequate substitutes, and that there seems to be no justification for its continued residual use in friction materials
• Limitations the authors state:
  • The lack of a full health and toxicologic data set prevents a comprehensive assessment of the safety of the substitute fibers
  • Less information is available for the substitute fibers than for chrysotile, especially on effects in humans
  • The paper covers health impacts only and does not include a cost-benefit analysis

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile, Amphibole Asbestos, Crocidolite, Amosite, Pleura, Asbestos-Cement, Deposition.

Related studies

• Man-made respirable-sized organic fibers: what do we know about their toxicological profiles? — D.B. Warheit, K.L. Reed, et al. (2001)
• Comments on "Comparative hazards of chrysotile asbestos and its substitutes: a European perspective" — H. Savastano (1999)
• Pulmonary effects in rats inhaling size-separated chrysotile asbestos fibres or p-aramid fibrils: differences in cellular proliferative responses — D.B. Warheit, M.A. Hartsky, et al. (1996)
• 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)
• A comparative study of the clearance of respirable para-aramid, chrysotile and glass fibres from rat lungs — A. Searl (1997)
• Cytotoxic effects of aramid fibres on rat pulmonary macrophages: comparison with chrysotile asbestos — J. Dunnigan, D. Nadeau, et al. (1984)

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