New recommendations for improving the working conditions of sewage workers

In June 2016, ANSES published an expert appraisal on the specific exposures and health risks to which sewage workers are subjected, concluding that there are long-term health effects associated with the working conditions in sewers. Today the Agency is presenting additional results from a campaign to measure biological agents potentially found in the air in the Paris sewers, carried out by the Ile-de-France regional health insurance fund (CRAMIF). The results of this campaign confirm that the drainage system in which the sewage workers operate on a daily basis is an unhealthy environment, a finding that had already been noted in the analysis of data on exposure to chemical pollutants published in the opinion of June 2016. The Agency is therefore recommending a series of technical and organisational measures to reduce worker exposure.

While carrying out their professional activity, sewer workers are exposed to many chemical and biological agents present in the air and/or water, by inhalation of gases, vapours or aerosols, by dermal contact or by ingestion.

In 2004, a study by the INRS had revealed excess mortality in Parisian sewage workers, particularly due to digestive diseases and cancers. These results, which were borne out when the study was updated in 2009, led ANSES to issue an internal request to assess the specific health risks for the occupation of sewer worker, and to identify the causes of this excess mortality.

In June 2016, therefore, the Agency published an initial opinion on occupational risk factors with a possible link to excess mortality among sewage workers (PDF) (in French). As part of the expert appraisal and in light of the limited data available, the Ile-de-France regional health insurance fund (CRAMIF) was asked to undertake research and development work to obtain data on the biological agents potentially found in sewer air. Given the complexity of the measurement campaign relating to these biological contaminants, it was not possible to integrate the resulting data in the opinion and expert appraisal report published in April 2016. The opinion published today therefore presents the results of the exploratory measurement campaign conducted from March 2015 to June 2016 to acquire data on several microbiological parameters in the atmosphere of the sewers in order to document current sewage worker exposure.

The results of this study show that sewer air contains high concentrations of endotoxins and microbial flora (including Aspergillus flavus), which are sometimes cause for concern according to the guideline values reference framework used by the Health Insurance - Occupational Risks network. These results confirm that the drainage system in which the sewage workers operate on a daily basis is a particularly unhealthy environment, a finding that had already been noted in the analysis of data on exposure to chemical pollutants published in the opinion of June 2016. Some tasks seem to involve especially high levels of exposure, particularly extraction work in the sand trap and high-pressure cleaning.

The Agency’s recommendations

In the first place, it should be remembered that the general principles of prevention laid down by the French Labour Code give priority to collective protective measures over personal protective measures.

The Agency reiterates that the occupational risk assessment process should be systematically conducted while analysing and mapping the different work situations, in order to prioritise and adapt the preventive measures to be put in place. In this context, particularly concerning the biological risks (infectious, immuno-allergic, toxin-induced and carcinogenic) for personnel working in systems in contact with wastewater, it is essential to characterise the nature of the pathogens found in sewer air. The Agency also recommends developing a common foundation of good prevention and hygiene practices, and assessing compliance with these practices on the ground.

In light of the high concentrations of chemical and microbiological pollutants in sewer air, personnel working in contact with wastewater must at least be able to naturally ventilate the systems before they enter them. For tasks carried out in fixed structures, it is recommended that mechanical ventilation systems that deliver fresh air be installed. The structural elements relating to ventilation must be included in the prevention plans.

It also seems important to consider any organisational measures that could reduce exposure, for example:

  • better coordination of teams to avoid concurrent work in the same place in the drainage system;
  • an increase in the frequency of cleaning, which should help reduce the levels of micro-organisms and endotoxins;
  • rotation of the teams.

In addition, the Agency recommends ensuring that the personal protective equipment available to the sewage workers does not increase their exposure to other risks – for example, the use of breathing apparatus can in some cases impede communication between sewage workers that is essential for preventing a potential hazard – and reiterates that this equipment must be worn and changed according to the manufacturer's recommendations, cleaned regularly, and stored outside the work area, if possible in specific premises.

Given the incidents identified and observations made during the measurement campaign, the Agency also recommends that communication campaigns aimed at professionals, particularly those working in construction and renovation, be carried out in such a way as to raise awareness of the impact of the various releases and discharges of building waste into the sewers, the consequences in terms of congestion of the system, and the additional risks incurred by the sewage workers.

Lastly, in this context, the Agency emphasises the importance of initiating a debate on the possibility of developing a reference framework for qualifying the health risks associated with microbiological hazards for the occupations that potentially involve the greatest exposure.