Asbestos-Environment Pollution Characteristics and Health-Risk Assessment in Typical Asbestos-Mining Area

Our plain-English summary of Asbestos-Environment Pollution Characteristics and Health-Risk Assessment in Typical Asbestos-Mining Area, by X. Li, Y. Chen, X. Li, et al (Toxics, 2023).

The study

• Authors: X. Li, Y. Chen, X. Li, M. Wang, W. Xie, D. Ding, L. Kong, D. Jiang, T. Long, S. Deng
• Journal: Toxics
• Published: 2023;11(6)
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Asbestos has been confirmed as a major pollutant in asbestos-mining areas that are located in western China. In general, asbestos-fibre dust will is released into the environment due to the effect of intensive industrial activities and improper environmental management, such that the health of residents in and around mining areas is jeopardised. A typical asbestos mining area served as an example in this study to analyse the content and fibre morphology of asbestos in soil and air samples in the mining area. The effects of asbestos pollution in and around the mining areas on human health were also assessed based on the U.S. Superfund Risk Assessment Framework in this study. As indicated by the results, different degrees of asbestos pollutions were present in the soil and air, and they were mainly concentrated in the mining area, the ore-dressing area, and the waste pile. The concentration of asbestos in the soil ranged from 0.3% to 91.92%, and the concentration of asbestos fibres in the air reached 0.008-0.145 f·cc-1. The results of the scanning-electron microscope (SEM) energy suggested that the asbestos was primarily strip-shaped, short columnar, and granular, and the asbestos morphology of the soils with higher degrees of pollution exhibited irregular strip-shaped fibre agglomeration. The excess lifetime cancer risk (ELCR) associated with the asbestos fibres in the air of the mining area was at an acceptable level (10-4-10-6), and 40.6% of the monitoring sites were subjected to unacceptable non-carcinogenic risks (HQ > 1). Moreover, the waste pile was the area with the highest non-carcinogenic risk, followed by the ore dressing area, a residential area, and a bare-land area in descending order. In the three scenarios of adult offices or residences in the mining area, adults' outdoor activities in the peripheral residence areas, and children's outdoor activities, the carcinogenic-and non-carcinogenic-risk-control values in the air reached 0.1438, 0.2225 and 0.1540 f·cc-1, and 0.0084, 0.0090 and 0.0090 f·cc-1, respectively. The results of this study will lay a scientific basis for the environmental management and governance of asbestos polluted sites in China.

In plain English

This study measured asbestos in soil and air at a chrysotile asbestos mining area in northwest China with a 62-year mining history. The area is not named in the article. The authors then estimated health risks from breathing the fibres using a U.S. EPA Superfund risk-assessment framework. No people were examined. Risks were calculated from measured air levels and assumed exposure patterns. Asbestos was found in all but eight of 94 soil samples, at 0.3% to 91.92%. Soil averages were highest in the mining area (39.06%) and the ore-dressing area (36.84%). In air, 23 of 57 samples were below the detection limit. Detected levels ranged from 0.008 to 0.145 fibres per cubic centimetre and were highest on average in the ore-dressing area (0.050). The authors reported that air levels exceeded foreign air-quality standards but were below China's occupational standard of 0.8. At 32 sites near human activity, estimated excess lifetime cancer risk fell in the range the authors called acceptable. They linked this to the relatively low outdoor exposure of the population. The non-cancer hazard index exceeded 1 at 13 of the 32 sites, with a maximum of 5.94. The authors concluded that their calculated risk-control values could guide air quality for offices and residences in mining environments.

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 survey of soil and air, with SEM fibre-shape analysis and a modelled (calculated, not observed) inhalation health risk assessment based on the U.S. Superfund asbestos framework
• Who was studied: A typical asbestos mining area in northwest China (about 14.11 km2, 62-year mining history) and residence areas northeast of its periphery. The authors took 94 soil samples and 57 ambient air samples from the mining area, the ore-dressing area, the waste-pile periphery, a residence area and bare land. Risk was assessed at 32 air sites for adults in mining-area offices and living areas, and for adults and children in peripheral residential areas. Sampling dates are not given.
• Exposure: Chrysotile asbestos from an open-pit chrysotile deposit, released from mining, ore dressing, tailings and waste piles. Airborne fibres were counted by phase contrast microscopy, counting fibres longer than 5 µm, narrower than 3 µm, and with a length-to-width ratio above 3:1. Soil asbestos was quantified by X-ray diffraction.
• Main results:
  • Soil: asbestos was not detected in eight of the 94 samples. In the others, concentrations ranged from 0.3% to 91.92%, with an average of 21.62%.
  • Average soil asbestos by area: mining area 39.06%, ore-dressing area 36.84%, waste-pile periphery 19.92%, residence area 6.69%, bare land 1.81%.
  • Air: 23 of 57 samples were below the detection limit. Airborne asbestos fibre concentrations ranged from 0.008 to 0.145 f·cc−1, with an average of 0.0224 f·cc−1.
  • Average airborne asbestos by area: mining area 0.025, ore-dressing area 0.050, waste-pile periphery 0.039, residential area 0.023, and bare land 0.012 f·cc−1.
  • The authors stated that the measured air levels exceeded air-quality standards set by foreign institutions but were lower than China's occupational health standard (0.8 f·cc−1).
  • At the 32 sites assessed, the estimated excess lifetime cancer risk was at an acceptable level (the authors used 1 × 10−4 to 1 × 10−6 as acceptable).
  • The cancer-risk result was sensitive to daily exposure time: a 10% change gave a parameter sensitivity of −91%. The authors attributed the low overall assessed risk to the population's relatively low outdoor exposure.
  • The non-carcinogenic hazard index (HQ) exceeded 1 at 13 of the 32 sites, which the authors reported as 40.6%. The maximum was 5.94. High-HQ sites were mostly downwind of tailing slag piles and dressing plants.
  • Excluding the mining area, the average non-carcinogenic risk ranked from highest to lowest as: waste-pile periphery, then ore-dressing area, then residential area, then bare land.
  • Calculated carcinogenic risk-control values in air were 0.1438 f·cc−1 for adults working or living in the mining area, 0.2225 for adults' outdoor activities in peripheral residence areas, and 0.1540 for children's outdoor activities.
  • Non-carcinogenic risk-control values in air for the same three scenarios were 0.0084, 0.0090 and 0.0090 f·cc−1.
  • Under SEM, fibre slenderness (length-to-diameter ratio above 3) ranked from highest to lowest as: finished asbestos products, then raw ore, then tailings, then dust-removal dust.
• The authors' conclusion: The authors concluded that soil and air in the area were polluted to different extents, concentrated around mining, ore-dressing and waste-pile areas. They proposed that their calculated risk-control values could serve as a guide value for air quality in office or residential settings in a mining environment.

Topics

Medical terms in this study, explained in our Lexicon: Superfund, Carcinogenic.

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