Where are the landfilled zones? Use of historical geographic information and local spatial knowledge to determine the location of underground asbestos contamination in Sibaté (Colombia)

Our plain-English summary of Where are the landfilled zones? Use of historical geographic information and local spatial knowledge to determine the location of underground asbestos contamination in Sibaté (Colombia), by B. Lysaniuk, M.F. Cely-García, A. Mazzeo, et al (Environmental Research, 2020).

The study

• Authors: B. Lysaniuk, M.F. Cely-García, A. Mazzeo, D. Marsili, R. Pasetto, P. Comba, J.P. Ramos-Bonilla
• Journal: Environmental Research
• Published: 2020;191:110182
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Introduction: Sibaté is a municipality located in the central region of Colombia, where the first asbestos-cement facility of the country has been in operation since 1942. Both a malignant pleural mesothelioma cluster and landfilled zones with the presence of an underground friable asbestos layer have been identified in Sibaté. There is still limited knowledge regarding the history of the construction of landfilled zones, and what kinds of materials were deposited. The current study aims to improve our understanding of the history and characteristics of the landfilled zones present in Sibaté.

Methods: Two participatory workshops with inhabitants of Sibaté were conducted to determine when the landfilled zones were built and their location. Information collected in participatory workshops was crossed with both topographic maps and aerial photographs, giving special attention to zones within the urban area of the municipality that in the past were inundated with water from El Muña Reservoir. An opportunistic soil sampling campaign was conducted in suspected landfilled zones that had not been previously sampled, during the replacement of pipelines of the drainage system ordered by the municipality.

Results: The analysis of historical topographic maps, combined with the interpretation of aerial photographs, confirmed the disposal of residues in areas that were previously inundated with water from El Muña Reservoir, creating landfilled zones in the urban area of Sibaté. On top of these landfilled zones, a football stadium and a football field with an athletic track were built. The location of landfilled zones identified using geographic analysis was similar to the location identified analyzing maps constructed by inhabitants of Sibaté in participatory workshops. The four soil samples collected during an opportunistic sampling campaign confirmed the presence in new locations of the underground friable asbestos layer discovered in previous studies.

Discussion: Based on the extension of the landfilled zones, the presence of friable asbestos in these areas, and the close proximity to a school and residential dwellings, there could have been major dispersion events of asbestos fibers in the urban area of Sibaté during the disposal of residue materials and the construction of the landfilled zones. Thus, important asbestos exposures may have occurred among residents of Sibaté, which is aggravated by the fact that during those years, more than 50% of the population of Sibaté was 25 years old or younger. Although the results of the current study improved our understanding of the processes and chronology associated with the landfilled zones, the uncertainty regarding their exact location remains significant. It is important to continue investigating the adverse health effects resulting from this potential asbestos exposure source.

Copyright © 2020 Elsevier Inc. All rights reserved.

In plain English

This study examined where and when waste was buried in 'landfilled zones' in Sibaté, Colombia, a town with an asbestos-cement plant that has processed asbestos since 1942. The authors compared historical topographic maps with aerial photographs from 1965 to 2005. They also held two mapping workshops with residents (11 people in 2018, 7 in 2019) and had four soil samples from municipal pipeline excavations analyzed. The photographs suggested that filling of areas once flooded by El Muña Reservoir began between 1974 and 1986. The southern flooded area dried out mostly in the late 1980s and the western area in the mid-1990s; about 4.5 hectares were filled in all. A football stadium and a football field with an athletic track now stand on them. Residents' maps broadly matched the photographs, and residents reported that some people took the material home. Three samples contained a friable layer with 10% chrysotile and 2% to 5% crocidolite, 64 to 109 cm deep. The fourth, dark brown soil, had 2% chrysotile. The authors noted that a link between the deposits and the plant has not been established. They called for a risk management plan.

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: Mixed-methods environmental study: analysis of historical topographic maps and aerial photographs in a geographic information system, participatory mapping workshops with residents, and an opportunistic soil sampling campaign with laboratory analysis by polarized light microscopy
• Who was studied: The urban area of Sibaté, Colombia. The study used topographic maps from 1950, 1978 and 1989 and aerial photographs from 1965, 1974, 1986, 1995 and 2005. Two workshops were held with residents who lived in Sibaté when the landfills were built: 11 people on April 28, 2018 and 7 people on March 30, 2019. Four soil samples were collected on October 19, 2018.
• Exposure: Residue materials deposited and compacted in former reservoir-flooded areas near an asbestos-cement facility operating since 1942. In the soil samples, a friable layer contained chrysotile and crocidolite. The origin of the residues was not established.
• Main results:
  • Aerial photographs suggested that filling of the formerly flooded zones began sometime between 1974 and 1986.
  • The southern flooded area dried out (desiccation) mostly during the late 1980s, and the western area in the mid-1990s. By 1986, more than 1 hectare of the southern zone had already been filled.
  • The total area filled with residues was approximately 4.5 hectares.
  • By 2005, a football field with an athletic track (west) and a football stadium (south) had been built on the filled zones.
  • Residents' workshop maps of the landfilled zones showed an important spatial correlation with the aerial photographs. In the second workshop, 6 of 7 participants stated that both sports facilities were built on landfilled zones.
  • Workshop participants reported that some inhabitants moved the disposed material to their dwellings to level floors or build foundations.
  • At three of the four sampled sites, the friable layer found in earlier studies was present, with 10% chrysotile and 2% to 5% crocidolite.
  • The fourth sample, dark brown soil, contained 2% chrysotile.
  • In the three samples where it was found, the friable layer lay between 64 cm and 109 cm deep.
  • Two of the four sample sites lay outside the 'probable' landfilled zone mapped from the 1974 photograph. The authors concluded that the real boundaries extend beyond the mapped limits.
  • From aerial photographs, the authors estimated that the largest disposal operations lasted 10 to 15 years, ending in the second half of the 1990s. Some residents estimated about 25 years.
  • From official population data, 56.4% of Sibaté's population was under 25 in 1986, and 51.2% in 1995.
• The authors' conclusion: The authors concluded that finding the friable asbestos layer at new locations highlights the importance of a risk management plan to prevent future exposures of the general population. They recommended additional non-invasive methods to locate the landfilled zones and the asbestos layer.
• Limitations the authors state:
  • The landfilled area may be underestimated, because it was based on the extent of formerly flooded areas.
  • In the first workshop, participants shared information while drawing maps that were meant to be individual. The authors said this may have biased the results.
  • Aerial photographs are snapshots with time gaps between them. They do not capture changes over time or seasonal variation in the reservoir.
  • The mapped boundaries could still miss areas where hazardous materials are present. Invasive soil sampling was not used, because of the risk of disturbing the asbestos layer.
  • A link between the asbestos-cement facility and the deposits has not been established.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Pleural Mesothelioma, Friable, Asbestos Exposure.

Related studies

• The challenges of applying an Activity-Based Sampling methodology to estimate the cancer risk associated with asbestos contaminated landfilled zones — M.F. Cely-García, B. Lysaniuk, et al. (2020)
• An Approach to Overcome the Limitations of Surveillance of Asbestos Related Diseases in Low- and Middle-Income Countries: What We Learned from the Sibaté Study in Colombia — J.P. Ramos-Bonilla, M. Giraldo, et al. (2023)
• Occupational burden of asbestos-related cancer in Argentina, Brazil, Colombia, and Mexico — R. Pasetto, B. Terracini, et al. (2014)
• Using GIS to Estimate Population at Risk Because of Residence Proximity to Asbestos Processing Facilities in Colombia — B. Lysaniuk, M.F. Cely-García, et al. (2021)
• Utilization of the seagrass Posidonia oceanica to evaluate the spatial dispersion of metal contamination — C. Lafabrie, G. Pergent, et al. (2009)
• Historical state of knowledge of the health risks of asbestos posed to seamen on merchant ships — D.G. Dodge, B.D. Beck (2016)

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