Bridging the gap between toxicity and carcinogenicity of mineral fibres by connecting the fibre crystal-chemical and physical parameters to the key characteristics of cancer

Our plain-English summary of Bridging the gap between toxicity and carcinogenicity of mineral fibres by connecting the fibre crystal-chemical and physical parameters to the key characteristics of cancer, by A.F. Gualtieri (Current Research in Toxicology, 2021).

The study

• Author: A.F. Gualtieri
• Journal: Current Research in Toxicology
• Published: 2021;2:42-52
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Airborne fibres and particularly asbestos represent hazards of great concern for human health because exposure to these peculiar particulates may cause malignancies such as lung cancer and mesothelioma. Currently, many researchers worldwide are focussed on fully understanding the patho-biological mechanisms leading to carcinogenesis prompted by pathogenic fibres. Along this line, the present work introduces a novel approach to correlate how and to what extent the physical/crystal-chemical and morphological parameters (including length, chemistry, biodurability, and surface properties) of mineral fibres cause major adverse effects with an emphasis on asbestos. The model described below conceptually attempts to bridge the gap between toxicity and carcinogenicity of mineral fibres and has several implications: 1) it provides a tool to measure the toxicity and pathogenic potential of asbestos minerals, allowing a quantitative rank of the different types (e.g. chrysotile vs. crocidolite); 2) it can predict the toxicity and pathogenicity of "unregulated" or unclassified fibres; 3) it reveals the parameters of a mineral fibre that are active in stimulating key characteristics of cancer, thus offering a strategy for developing specific cancer prevention strategies and therapies. Chrysotile, crocidolite and fibrous glaucophane are described here as mineral fibres of interest.

© 2021 The Author.

In plain English

This article was a theoretical modelling paper by a single author, not an experiment and not a study of people. The author linked 18 physical, chemical and shape properties of mineral fibres, taken from the author's earlier Fibre Potential Toxicity/Pathogenicity Index (FPTI), to the 10 key characteristics of cancer-causing agents listed by an IARC working group. The author reasoned that fibre length, biodurability (slowness of dissolving), surface area, metal content and surface charge were each linked to nearly all key characteristics. FPTI scores were 2.22 (error 0.28) for a standard UICC chrysotile sample, 2.73 (0.18) for UICC crocidolite and 2.77 (0.25) for an unregulated fibrous glaucophane from Marin County, California. The author judged non-biodurable chrysotile less active than crocidolite for most key characteristics, but more active for three through faster silica release. The author concluded that the view that long, thin, biodurable fibres are toxic is only approximate. The author stated that predictive power is limited because few cases had been considered, and that the model does not address dose.

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: Theoretical/conceptual modelling paper (no new experiments): the author's existing FPTI index was linked by deductive reasoning to the IARC key characteristics of carcinogens and applied to three fibre samples
• Who was studied: No human or animal subjects; three mineral fibre samples: UICC standard chrysotile "B", UICC standard crocidolite, and fibrous glaucophane from the Franciscan Complex, Marin County (San Anselmo), California, USA
• Exposure: 18 fibre parameters (length, width, crystal curvature, crystal habit, density, surface hydrophobicity, surface area, iron and other metal content, dissolution rate, release rates of iron, silica and metals, zeta potential, aggregation, cation exchange) for chrysotile, crocidolite and fibrous glaucophane
• Main results:
  • Length and biodurability-related parameters were linked to adverse effects connected with nearly all key characteristics of cancer
  • Surface area, metal-content parameters and zeta potential were also linked to nearly all key characteristics of cancer
  • Crystal habit and fibre density were judged to have no direct connection with the key characteristics of cancer, though they affect how deep fibres deposit in the lung
  • For immortalization (key characteristic 9), the author found no literature data linking it to asbestos
  • Final FPTI was 2.22 (error 0.28) for UICC chrysotile and 2.73 (error 0.18) for UICC crocidolite; these values were calculated in the author's earlier work (Gualtieri, 2018)
  • Dissolution rate was identified as the key parameter distinguishing chrysotile from crocidolite; non-biodurable chrysotile was judged less active than crocidolite in stimulating key characteristics 1 to 7
  • Because silica is released faster from chrysotile, chrysotile was judged more active than crocidolite for electrophilicity, genotoxicity and oxidative stress
  • Fibrous glaucophane from San Anselmo scored an FPTI of 2.77 (error 0.25), comparable to crocidolite's 2.73 (error 0.18); its glaucophane FPTI data came from Di Giuseppe et al., 2019
  • Only fibre length and silica dissolution rate differed significantly between glaucophane and crocidolite; with a mean length under 5 micrometres (per Di Giuseppe et al., 2019), glaucophane's length was considered inactive for the related key characteristics
• The authors' conclusion: The author concluded that the 'fibre toxicity paradigm' (long, thin, biodurable fibres are highly toxic) is only an approximate model, and that the fibre's nature in its entirety dictates its toxic and pathogenic action and its power to induce cancer
• Limitations the authors state:
  • The predictive power and impact of the model are limited because only a few cases have been considered so far
  • The model does not address dose, time or dose-response, so it cannot say whether a given cumulative dose of a fibre causes disease
  • The adverse effects in the model do not refer to any specific lung disease
  • The author states that in the future the model should be merged with other models that incorporate dose/time dependency and cancer dose-response

Topics

Medical terms in this study, explained in our Lexicon: Lung Cancer, Mesothelioma, Carcinogenesis, Asbestos, Chrysotile, Crocidolite.

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