Health risks associated with swimming pools for collective use

Health risk assessment and regulations on swimming pools and jacuzzis

In France, bathing is the most common water-based recreational activity. The three main types of areas for bathing and related activities are 1) public swimming pools, in which the water is disinfected and provided with disinfectant properties so as to ensure its compliance with microbiologic standards, 2) natural bathing sites which sometimes benefit from specific improvements for the general public, but whose water is not treated and 3) artificial bathing sites. ANSES assesses the potential health risks associated with these three types of bathing areas. Read more about the Agency’s work on swimming pools here.

Assessment of health risks related to swimming pools

The 1981 regulations for swimming pools require updates to take into account changing practices. For instance when French health regulations were drawn up for public swimming pools, other types of pools such as Jacuzzis were still extremely rare and their specific characteristics were not taken into account. In order to do the updating, the respective Ministries for Health and the Environment asked the Agency to review all possible health risks associated with swimming pools.

The Agency’s work was conducted in two phases and focused on:

  • regulated swimming pools(according to the meaning of Article D1332-1 of the French Public Health Code). These pools are designed for sports or recreation, and are supplied by water from the public distribution system. This concerns swimming pools run by local authorities, hotels, campsites, holiday apartment complexes, rented lodges, etc.;
  • jacuzzis, whether supplied with water intended for human consumption, with seawater or with natural mineral water.

The expert group identified the main chemical and microbiological hazards found in water, air and on surfaces of regulated swimming pools and Jacuzzis. The hazards were characterised according to the source of the water in the pools.

The chemical hazards

The chemical hazards identified are due mainly to substances formed from reactions between disinfection products (mainly chlorine) and organic matter brought in by bathers. Among the more than 400 substances listed for regulated swimming pools, only 10 were selected for the health risk assessment, due to their toxicity and high concentration levels in water. The substances selected were trichloramine, trihalomethanes, haloacetic acids and bromate.

According to the predefined scenarios and populations observed (babies, children, athletes, workers, pregnant women), the study did not find any health risks for these substances, except for trichloramine which might be responsible for respiratory and eye disorders in elite swimmers, swimming instructors/lifeguards and infant swimmers; and another substance, dichloroacetic acid, that may be responsible for hepatocellular adenoma and carcinoma in elite swimmers.

The microbiological hazards

The microbiological hazards were analysed and potentially-pathogenic waterborne germs found in regulated swimming pools were identified. Even though no outbreaks have yet been declared in France up to now, it would appear that the microbiological risk is mainly due to the bathers' lack of hygiene.

These same substances and pathogenic germs are also sometimes found in Jacuzzis. However these pools have certain characteristics which may change the ranking of the hazards described and/or may cause other relevant hazards. These characteristics are:

  • the high temperature of the water;
  • the presence of bubble nozzles;
  • the low volume of water in proportion to the number of bathers using Jacuzzis;
  • insufficiently frequent renewal of water in proportion to the number of bathers;
  • fluctuating concentrations of disinfectant;
  • an increase in the pH;
  • close proximity of bathers.

The Agency’s recommendations

The recommendations based on this expert appraisal are intended to improve management of the quality of water, air and surfaces of pools. The preventive measures relate in particular to:

  • hygiene: strict compliance of bathers with hygiene measures; optimisation of layout, maintenance and cleaning of premises; prior authorisation of the use of cleaning products and supplementary treatments for disinfecting the water; 
  • treatment of water in the pools: measures concerning the hydraulic system, the disinfection of foot baths, filtering, disinfection; 
  • parameters for inspecting and monitoring the quality of water during mandatory health inspections and inspections made by operators
  • inspecting the quality of the air: even though this is not mandatory for swimming pools, some disinfection by-products found in air, such as chloroform and trichloramine, are toxic.
  • supervision by medical practitioners, which is recommended in particular for swimming instructors/lifeguards.

Given that the advantages for infant swimmers outweigh the risks that might be run by this particularly vulnerable population, the Agency recommends that great care be taken when engaging in this activity.

Assessment of products and processes for treating swimming pool water

According to the provisions of the French Public Health Code (Article D.1332-3), ANSES is responsible for assessing marketing authorisation applications for new products and processes for disinfecting and removing chloramines from swimming pool water. This procedure is not applicable for the disinfection products covered by the European Community Directive 98/8/EC concerning the placing of biocidal products on the market.

Procedure for applying for marketing authorisation

Petitioners send their applications to the Directorate General for Health (DGS) which then sends them to ANSES for an Opinion. These applications have to follow the guidelines drawn up by the Agency.

The requisite items for the dossier should enable the Agency to assess the efficacy and safety of the treatment products and processes for which claims are being made. The guidelines only apply to applications for authorisation of treatment products and processes used in public swimming pools filled with water from a public or private supply which has been approved for human consumption.

In the event that the treatment product and/or process has already been authorised in a Member State of the European Union or in a Member State signatory of the founding agreement for the European Economic Community, a simplified application dossier is sufficient.

The final notification, based on the Agency's Opinion, is issued by the DGS and sent to the petitioner.

Dechlorination and reactors fitted with ultraviolet lamps 

The use of reactors fitted with ultraviolet (UV) lamps is one of the solutions proposed to swimming pool managers to reduce the concentration of chloramines in the water and air of the pools. However, the photochemical degradation mechanisms of chloramines and the impact of UV radiation on all the organic compounds present (disinfection products, and especially disinfection by-products) liable to react with the UVs to form new substances, are only partially known. The Agency therefore carried out an expert appraisal to review current knowledge on the effectiveness and safety of this type of process.

The expert appraisal demonstrated that the use of UV dechlorinators to treat swimming pool water would moderately reduce concentrations of combined chlorine and of trichloramine under certain pool operating conditions. However, under certain conditions, the use of these processes can lead to the formation of new compounds and an increase in the concentration of compounds initially found in the water and air, in particular chloroform.