A critical review of asbestos concentrations in water and air, according to exposure sources

Our plain-English summary of A critical review of asbestos concentrations in water and air, according to exposure sources, by M. Peña-Castro, M. Montero-Acosta, M. Saba (Heliyon, 2023).

The study

• Authors: M. Peña-Castro, M. Montero-Acosta, M. Saba
• Journal: Heliyon
• Published: 2023;9(5):e15730
• Type of article: Review
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Asbestos, a group of minerals with unique physical and chemical properties, has been widely used in various industries. However, extensive exposure to asbestos fibers, present in the environment, has been linked to several types of cancer, mesothelioma, and asbestosis. Despite worldwide regulations prohibiting or regulating the use of this material, the uncertainty surrounding the concentrations of asbestos fibers in the environment (air and water) from different sources of exposure persists. The objective of this review paper is to identify the levels of asbestos in air and water reported in the literature based on the source of exposure in diverse contexts to assess conformity with the reference limits for this mineral. Initially, the review delineates various forms of exposure and the origin of fiber generation in the environment, whether direct or indirect. Regarding the presence of asbestos in the environment, high concentrations were identified in natural water bodies known as Naturally Occurring Asbestos (NOA), and there is a risk in the process of distributing drinking water due to the presence of asbestos-cement pipes. In the air, studies to determine asbestos concentrations vary based on the sources of exposure in each region or city studied. The presence of asbestos mines around the city and the intensity of vehicular traffic are some of the most relevant sources found to be related to high concentrations of asbestos fibers in the air. The present review paper features a critical review section in each chapter to highlight critical points found in the literature and suggest new methodologies/ideas to standardize future research. It emphasizes the necessity to standardize methods for measuring asbestos concentrations in air and water arising from diverse sources of exposure to enable comparisons between different regions and countries.

© 2023 The Authors.

In plain English

This was a review article. The authors searched the literature, including 803 Scopus documents found with the keywords "asbestos and concentration". They summarized studies that measured asbestos in water and air, grouping exposure as domestic, environmental or occupational. The reviewed studies reported high levels in natural waters near asbestos sources. One was a Greek river near an inactive mine, with 4.3 to 152 million chrysotile fibers per liter. Another was well and surface water in a crocidolite-rich area of Dayao, China, with a mean of 42.34 million fibers per liter. For comparison, the US EPA limit is 7 million fibers per liter for fibers longer than 10 micrometers. In Christchurch, New Zealand, 19 of 20 drinking-water samples contained asbestos fibers. For air, the reviewed studies linked higher levels to nearby mines and heavy vehicle traffic. The authors wrote that there is so far no convincing evidence of health risk from asbestos in water, but concluded this possibility should not be dismissed. They called for standardized measurement methods using transmission electron microscopy, and said their table of air studies was not exhaustive.

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: Critical literature review with a bibliometric analysis of published studies (no new measurements)
• Who was studied: Published studies worldwide on asbestos concentrations in air and water, including 803 documents from a Scopus keyword search
• Exposure: Asbestos fibers in water and air, grouped by source into domestic, environmental and occupational exposure. Sources discussed include naturally occurring asbestos, asbestos mines, asbestos-cement pipes and roofs, and vehicle brakes and clutches.
• Main results:
  • Reference value used for comparison: the US EPA limit for drinking water is 7 million fibers per liter, for fibers longer than 10 micrometers
  • In a reviewed study of the Aliakmonas river, Greece, near an inactive asbestos mine, chrysotile concentrations were 4.3 to 152 million fibers per liter
  • In a reviewed study of well and surface waters in a crocidolite-rich rural area of Dayao, China, the mean concentration was 42.34 million fibers per liter (by SEM)
  • In a reviewed study of Christchurch, New Zealand, drinking water with aging asbestos-cement pipes, 19 of 20 samples had long and short asbestos fibers, with average concentrations of 0.9 and 6.2 million fibers per liter respectively
  • A reviewed study in Yazd, Iran, found dense traffic to be one of the main sources of asbestos fibers in urban air, attributed to automobile braking and clutching
  • In a reviewed study of an asbestos-cement sheet factory in Iran (45 personal air samples), 15.5% of samples exceeded the ACGIH limit of 0.1 fibers per milliliter
  • A reviewed Colombian study estimated that in 2005, 10,489 people in the country lived within 500 m of an asbestos processing plant or mine
  • The authors stated that, so far, there is no convincing evidence of human health risk from asbestos in water
• The authors' conclusion: The authors concluded that the possibility of asbestos in drinking water causing cancer should not be dismissed. They called for standardized measurement methods, with water samples analyzed by transmission electron microscopy (TEM) so that results are reliable and comparable between countries.
• Limitations the authors state:
  • The authors stated that their compilation of air studies (Table 5) was not meant to be exhaustive or comprehensive, only an initial framework for future research
  • The authors noted that few studies have examined airborne asbestos levels in relation to different sources of exposure

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, naturally occurring asbestos (NOA), Asbestos-Cement Pipe.

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