Asbestos contamination on brownfield development sites in the UK

Our plain-English summary of Asbestos contamination on brownfield development sites in the UK, by E.E. Hellawell, S.J. Hughes (Environmental Research, 2021).

The study

• Authors: E.E. Hellawell, S.J. Hughes
• Journal: Environmental Research
• Published: 2021;198:110480
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The development of brownfield sites in the UK requires site investigation for contamination as part of the regulatory planning process. This site investigation includes the collection of soil samples that are analysed for asbestos contamination. This research project analyses this untapped resource of brownfield asbestos data, using site investigation data submitted to a local Borough Council, in Surrey, UK. Over 100 site investigation reports were collected. This paper presents the trends in asbestos testing from 2001 to 2019 and data on the location, concentration, form and type of asbestos found in this Borough. The rate of asbestos detection has increased significantly, reflecting improvements in asbestos measuring techniques, to a rate of 22% for all samples tested between 2016 and 2019. The concentrations of asbestos found were very low, with 74% of samples having concentrations below the limit of detection of the laboratory and were predominantly of fibrous form. A significant proportion of samples contained more carcinogenic amphibole type. Most of the asbestos was found in the top 1 m of Made Ground soil. Site history was found to be important with gas works having the highest asbestos detection rate, though a detection rate of 10% was found in soil samples on former residential sites. This information is important to inform and update risk assessment for site workers and site remediation in relation to asbestos. Hence based upon these results, a qualitative risk chart for asbestos is presented to provide guidance and in-sight into asbestos on brownfield sites for local authorities and developers.

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In plain English

This study analysed site investigation reports for brownfield (previously developed) sites that were submitted to Elmbridge Borough Council in Surrey, UK, covering investigations carried out between 2001 and 2019. The reports covered 120 sites and 1714 soil samples. Of these, 789 samples were tested for asbestos, and asbestos was identified in 103, an overall detection rate of 13%. In Made Ground (man-made fill) samples, 8 of 149 tested before 2012 (5.4%) were positive, compared with 94 of 495 tested after 2012 (19.0%). The authors linked this rise to improved laboratory methods. Among samples with asbestos, chrysotile was found in 62%, amosite in 24% and crocidolite in 14%. Most (74%) were below the laboratory's limit of detection, and most asbestos was fibrous and within the top 1 m of Made Ground. A former gasworks had the highest detection rate. The authors stated that the testing methods were not the most advanced or reliable. Fibre release into air was not measured. From these results the authors developed a qualitative asbestos risk chart for brownfield sites.

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: Retrospective analysis of existing commercial site investigation data (soil test results) held in a local council planning database; not a health study
• Who was studied: Soil samples from 120 brownfield development sites in Elmbridge Borough, Surrey, UK, drawn from 132 site investigation reports covering investigations from 2001 to 2019. The reports held 1714 soil samples from 1172 sampling locations, of which 789 (46%) were analysed for asbestos.
• Exposure: Asbestos in soil (chrysotile, amosite, crocidolite), tested by UKAS-accredited commercial laboratories. Before about 2012 some laboratories reported 'visual' identification; after 2012 all used staining with polarised light microscopy (PLM). Transmission electron microscopy (TEM) was not used.
• Main results:
  • Asbestos was identified in 103 of the 789 soil samples sent for asbestos analysis, an overall detection rate of 13%.
  • Made Ground samples tested before 2012: 8 positive out of 149 (5.4%). Made Ground samples tested after 2012: 94 positive out of 495 (19.0%).
  • The yearly detection rate started to improve around 2012 and reached 33% in 2019. Across all samples tested in 2016 to 2019, the detection rate was 22%.
  • Among samples where asbestos was found, chrysotile was found in 62%, amosite in 24% and crocidolite in 14%. Some samples contained more than one type.
  • Among samples where asbestos was found, 74% had concentrations below the laboratory's limit of detection, generally 0.001% weight for weight. 71.5% were fibrous and 17% contained asbestos cement.
  • Asbestos was found mainly in the first 1 m of Made Ground. Below 1.5 m it was found only in former infilled gravel pits or landfill.
  • A former gasworks had the highest asbestos detection rate. That site was investigated 30 years after it had been remediated for residential use.
  • A high percentage of samples from former gasworks, print works and cement manufacturing sites contained amphibole asbestos (amosite and crocidolite).
  • The authors reported that asbestos detection decreased significantly for sites first developed after 1980. No particular earlier age of site was identified as affecting detection.
  • 12% of samples sent for asbestos analysis came from deep within natural ground, where the authors considered asbestos unlikely to be present.
• The authors' conclusion: The authors concluded that the key factors for asbestos detection were previous site history, date of survey, type, form, concentration and soil depth. On this basis they developed a qualitative asbestos risk chart for brownfield sites.
• Limitations the authors state:
  • The methods used to detect and quantify asbestos were not the most advanced or reliable.
  • Before 2012, asbestos testing of soil samples was sparse and the measuring techniques were unreliable.
  • Transmission electron microscopy was not used in the dataset.
  • Only a small subset of the national data, from one local authority, was analysed.
  • The sample sets for some higher-risk former site uses, such as printworks and dockyards, were small.
  • There was no information on when asbestos may have been used on a site.
  • Fibre release, and therefore actual exposure of site workers and users, was not evaluated.

Topics

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

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