Introduction Releases from asbestos abatement activities, asbestos-cement pipes and natural sources may contaminate wastewater with asbestos fibres. However, asbestos exposures in wastewater collection and treatment (WCT) workers are insufficiently characterized.

Objective To identify workers at risk of asbestos exposure in the WCT sector in France.

Methods We conducted a search of the international literature to identify sources of asbestos exposure and risks of asbestos-related diseases in WCT workers. We also extracted measurements from occupations related to WCT activities contained in two large French administrative databases of workplace measurements (Colchic and Scola) collected since 1987.

Results Studies conducted in the United States in the 1990s showed detectable concentrations of asbestos fibres in sewage sludge from several cities, with residual concentrations varying between disposal methods (e.g., incineration, composting). We identified six cohort studies of sewer workers and/or treatment plant operators. Five studies reported non-significant increases of respiratory cancer incidence or mortality, and one study of French sewer workers showed increased mortality from mesothelioma. Analyses of the two databases provided 2886 measurements from 13 occupations and collected from 2003 to 2020, with 58% below the limit of detection. Ninety-fifth percentiles of asbestos concentrations by occupation were 22 f/L for sewer workers (n=135), 148 f/L for sanitary systems control technicians (n=36), and ranged between 185 to 520 f/L for pipe laying, installing, or removal occupations. Sewer cleaners (n=12) and sewer workers supervisors (n=24) had no detectable concentrations of asbestos fibres.

Conclusion The available literature and the reported presence of fibres in sewage sludge suggest that WCT workers are potentially exposed to asbestos at various endpoints of the wastewater collection and treatment process. While asbestos exposure levels for most workers are likely to be low, a detailed risk assessment was not possible because of a lack of quantitative measurement data.