Background
Asbestos consists of a group of mineral fibers that have been extensively used. All forms of asbestos are classified as carcinogenic to humans; however, many low- and middle-income countries have not banned asbestos yet. Furthermore, the health impacts of asbestos exposure remain underestimated due to insufficient environmental surveillance, and lack of both occupational records and disease registries.
Colombia’s first asbestos-cement production facility was established in 1942 in the municipality of Sibaté, prior to the creation of the regional environmental authority in 1960. The first cluster of malignant pleural mesothelioma in Colombia was identified in this municipality, and large areas with soil asbestos contamination have been documented, with no remediation strategy currently in place.
Although Colombia banned asbestos in 2019, experience demonstrates that, even after the enactment of asbestos bans, long-term public policy interventions are necessary to prevent ongoing and future exposures—interventions that are still largely lacking in Sibaté.

Objectives
This study aims to identify areas within the facility with the highest potential for asbestos exposure based on worker interviews, and to assess the potential release of asbestos fibers from the facility, through a review of public environmental surveillance records from the Regional Environmental Authority. By addressing these knowledge gaps, the study provides insights into methods for collecting and interpreting information on asbestos-contaminated sites, such as Sibaté, that can generate actionable evidence to support cancer risk management, and the prevention of ongoing and future asbestos exposure in data-scarce settings.

Methods
Using interviews with former workers, we reconstructed historical production processes and assessed potential asbestos exposure risks across different key stages and activities within the asbestos-cement production facility. This analysis was complemented by a review of environmental surveillance records specifically related to the asbestos-cement facility, obtained from the Regional Environmental Authority and covering the 1980–2019 period. These records were analyzed to identify documented pollution events, regulatory oversight, and gaps in monitoring across time.

Results
The reconstruction of production processes revealed operational stages and activities likely associated with asbestos releases, including raw material handling, wastewater discharge, sludge disposal, and landfilling of asbestos-containing waste within and beyond the municipality. Records from the environmental authority revealed a 38-year gap between the onset of industrial operations and the implementation of environmental surveillance, with no asbestos-specific measurements during the surveillance period. More than 37 years of available evidence indicated discharges of industrial wastewater contaminated with asbestos, and the disposal of asbestos-contaminated residues in the surrounding areas. These findings suggest prolonged and undocumented environmental asbestos pollution affecting the region, consistent with the health impacts observed in the community.

Conclusions
The Sibaté case demonstrates how the integration of worker-based process reconstruction with long-term environmental surveillance data can generate otherwise unavailable actionable evidence. The approach implemented in this study supports the identification and management of legacy asbestos risks in contexts where conventional exposure data are lacking. The methodology is transferable to other contexts of legacy industrial pollution in low- and middle-income countries and contributes to capacity-building for translating historical exposure research into public health action.