OECD 170-4-Disinfectants activity for swimming pools and SPAs with bacteria, viruses and protozoa cysts. OECD 170-4: 2012.
Test accredited by ENAC (National Accreditation Entity) for bactericidal and fungicidal activities.
For many years the disinfection of swimming pools and spas has been based on chemical disinfection with chlorine or bromine products whose effectiveness is well known for various kinds of pathogenic microorganisms. The effectiveness of disinfectants must meet in new conditions in swimming pools and SPAs before being approved for use. In addition, for new disinfectants should be tested safety for human health and the environment, before efficacy tests performed, and laboratory tests or field trials.
Efficacy criteria: the activity of new products to various pathogens human pathogens indicators (bacteria, viruses and protozoa), which can often be found in the water of the swimming pools or SPAs must be set against and must have in front of them a equivalent to that obtained with chlorine derivatives activity. Moreover, the new products should have the following characteristics: 1) Maintaining an effective residual concentration in the pools to provide continuous disinfection in water. 2) In the case of public pool it should be able to be dispensed through an automatic dosing system; 3) The effectiveness must be maintained at a pH range chosen by the manufacturer, consistent with safety and human comfort, which can be maintained in the presence of ions and other solutes concentrations usually found in water pools; 4) must have a practical method to measure its concentration, which can even be determined by particular users; 5) should be added extra doses power when concentrations fall below the recommended effective concentration, or if microbial contamination is detected; 6) a margin of effectiveness should be established for normal use concentrations; 7) For disinfectants containing more than one active substance must know the relative contribution of each component on the overall efficiency; 8) The disinfectant must have algicide properties that have been proven or that their use is compatible with other algicides products.
Laboratory evaluation phase: In this phase the activity is evaluated against microorganisms indicators of major groups (bacteria, viruses and protozoa) associated with swimming pools and SPAs in defined laboratory conditions. In the event that for some reason should surrogate microorganisms used, they must be accepted by the appropriate regulatory agency in charge of product registration. In conducting tests with chlorine control should be included, including the determination of free chlorine at the beginning and the end of the test. Tests should be performed at a temperature between 25 and 30ºC for swimming pools and between 34 and 36ºC for SPA pools and pH conditions that allow the disinfectant efficiency and acceptable to the comfort and safety of users. For controls, chlorine pH should be 7.2 to 7.3. In tests a representative interfering substance clean conditions should be included. The disinfectant must be effective to 50% of the recommended concentration to allow a margin covering periods of decreased concentrations during use by dosing errors or automatic dosing systems. This margin can be calculated with a single strain as Pseudomonas aeruginosa. For products with more than one active component (e.gr., metals and oxidants) must be demonstrated activity each. The strains used will be obtained from recognized collections. Contact times are those indicated below for each microorganism. Test volume to volume of inoculum is 199: 1. With neutralizer control it should be included with the corresponding validation tests. Determining the product concentration at the beginning and end of the tests to be performed, and controls with chlorine. Inoculum density should be 100 times the logarithm of the required reduction. All tests must be performed at least in duplicate. The microorganisms used are: Escherichia coli, Enterococcus faecium, Pseudomonas aeruginosa, Legionella pneumophila, Staphylococcus aureus, Adenovirus, Rotavirus, Naegleria fowleri cysts, Giardia intestinalis or Giardia muris cysts. Contact times will be 30 seconds for all bacteria except for Enterococcus faecium 2 minutes; Adenovirus (10 minutes); Rotavirus (2 minutes); Naegleria fowleri (30 minutes); and Giardia spp. (45 minutes). Reducing microorganisms obtained should be 4 log10 for the five species bacteria, 3 log10 for the two viruses, and 4 and 3 log10 reduction in the number of cysts for Naegleria fowleri and Giardia intestinalis, respectively.
Field evaluation phase in real pools: before being approved for use, the product must be evaluated under field conditions of use, preferably a pool and/or crowded SPAs. In these cases no microorganisms were added, but must be sampled from areas where they can meet regularly. To perform field tests before must have passed safety tests for human and environmental health. Field tests must be designed for a minimum period of 3 months and must be accepted by the regulatory agency responsible for registration. Tests must be done following the ISO 6222 standards for aerobes count showing that there are fewer than 100 CFU/mL; thermotolerant coliforms to ISO 9308-1 following the standard for detecting coliforms and E. coli, demonstrating that are not detected in 100 mL; and Pseudomonas aeruginosa following the ISO 16266 standard, demonstrating that are not detected in 100 mL. The design of the field study will include the pool specifications regarding dimensions, volume and location; water distribution and circulation; the replacement rate; dosing methods for disinfectant; filtration, flocculation; presence of rain for outdoor pools; The methodology for the microorganisms tested; the location of sampling for microorganisms and disinfectants; transport conditions of samples; the sampling design; temperature measurements and water transparency; the number of bathers; the ratio of sampling with bathers; the concentration of disinfectant at the time of sampling; pH measurement at the time of sampling; measuring total alkaline reserve; the concentration of any other relevant chemical; etc.