Concentrations of asbestos fibers and metals in drinking water caused by natural crocidolite asbestos in the soil from a rural area

Our plain-English summary of Concentrations of asbestos fibers and metals in drinking water caused by natural crocidolite asbestos in the soil from a rural area, by B. Wei, B. Ye, J. Yu, et al (Environmental Monitoring and Assessment, 2013).

The study

• Authors: B. Wei, B. Ye, J. Yu, X. Jia, B. Zhang, X. Zhang, R. Lu, T. Dong, L. Yang
• Journal: Environmental Monitoring and Assessment
• Published: 2013;185(4):3013-22
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Asbestos fibers and metals in drinking water are of significant importance to the field of asbestos toxicology. However, little is known about asbestos fibers and metals in drinking water caused by naturally occurring asbestos. Therefore, concentrations of asbestos fibers and metals in well and surface waters from asbestos and control areas were measured by scanning electron microscopy (SEM), inductively coupled plasma (ICP) optical emission spectrometer, and ICP-mass spectrometry in this study. The results indicated that the mean concentration of asbestos fibers was 42.34 millions of fibers per liter by SEM, which was much higher than the permission exposure level. The main compositions of both asbestos fibers in crocidolite mineral and in drinking water were Na, Mg, Fe, and Si based on energy dispersive X-ray analysis. This revealed that the drinking water has been contaminated by asbestos fibers from crocidolite mineral in soil and rock. Except for Cr, Pb, Zn, and Mn, the mean concentrations of Ni, Na, Mg, K, Fe, Ca, and SiO2 were much higher in both surface water and well waters from the asbestos area than in well water from the control area. The results of principal component and cluster analyses indicated that the metals in surface and well waters from the asbestos area were significantly influenced by crocidolite mineral in soil and rock. In the asbestos area, the mean concentrations of asbestos fibers and Ni, Na, Mg, K, Fe, Ca, and SiO2 were higher in surface and well waters, indicating that asbestos fibers and the metals were significantly influenced by crocidolite in soil and rock.

In plain English

This study measured asbestos fibers and metals in drinking water in Dayao, a rural area of Yunnan province, China, where a thin layer of naturally occurring crocidolite ("blue asbestos") is exposed across about 5% of the land. The authors analyzed 12 crocidolite rock samples. They counted fibers by scanning electron microscopy in 15 water samples (10 well, 5 surface) and measured metals in 44 water samples (33 from the asbestos area, 11 from a control area). The mean fiber count across all water samples was 42.34 million fibers per liter, above the seven million that the authors gave as the US EPA permissible level. Surface water averaged 109.82 million fibers per liter (range 15.10 to 399.00). Well water averaged 8.60 (range 0.94 to 50.20). Fibers in the water had the same main elements as the crocidolite: iron, magnesium, sodium and silicon. Nickel, iron, calcium, magnesium and sodium were higher in asbestos-area water than in control-area well water. The authors concluded that the fibers came mainly from crocidolite in soil and rock, and that crocidolite influenced metal levels in asbestos-area water. The study did not examine residents' health.

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: Environmental sampling study: crocidolite rock and drinking water samples analyzed for asbestos fibers (scanning electron microscopy with energy dispersive X-ray analysis) and metals, with principal component and cluster analyses comparing an asbestos area with a control area; no health outcomes were measured
• Who was studied: Dayao, a rural area in Yunnan province, China. Samples were 12 crocidolite mineral samples collected in 2011, 15 drinking water samples (10 well, 5 surface) from different villages analyzed for fibers, and 44 water samples (33 from the asbestos area, 11 from a control area) analyzed for metals
• Exposure: Naturally occurring outcrop crocidolite (called "blue asbestos" locally) in soil and rock, covering about 5% of Dayao's surface area; residents mainly drink well and surface water
• Main results:
  • Mean asbestos fiber concentration across all drinking water samples was 42.34 million fibers per liter (MFL), which exceeded the permissible exposure level
  • The authors gave the USEPA permissible exposure level for asbestos in drinking water as seven million fibers per liter
  • Surface water in the asbestos area had a minimum of 15.10 MFL, a maximum of 399.00 MFL and a mean of 109.82 MFL, all higher than in well water
  • Well water had a minimum of 0.94 MFL, a maximum of 50.20 MFL and a mean of 8.60 MFL
  • Fibers in drinking water and in the crocidolite mineral had the same main elements: iron, magnesium, sodium and silicon
  • Nickel, iron, calcium, magnesium and sodium were much higher in surface and well water from the asbestos area than in well water from the control area
  • Mean nickel was 3.78 μg/L in asbestos-area surface water, 3.59 μg/L in asbestos-area well water, and 1.01 μg/L in control-area well water
  • In the crocidolite mineral samples, mean nickel, zinc, CaO, Fe2O3, MgO and Na2O were higher than background values in soil, while the other metals were lower
  • The authors interpreted the principal component and cluster analyses as showing that metals in asbestos-area surface and well water were influenced by crocidolite in soil and rock
• The authors' conclusion: The authors concluded that well and surface water in the asbestos area were contaminated by asbestos fibers derived mainly from crocidolite in soil and rock, with higher contamination in surface water than in well water. They also concluded that crocidolite influenced metal levels in the water, and called for further investigation of asbestos fibers combined with metals in drinking water.

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, naturally occurring asbestos (NOA), Scanning Electron Microscopy (SEM).

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