NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.
Prud’homme de Lodder LCH, Bremmer HJ, Pelgrom SMGJ, et al. Disinfectant Products Fact Sheet: To assess the risks for the consumer [Internet]. Bilthoven (NL): National Institute for Public Health and the Environment; 2006.
Disinfectant Products Fact Sheet: To assess the risks for the consumer [Internet].
Show details6.1. Introduction
To control quality of swimming pool water, a filtering system is usually not adequate. To control or prevent growth of organisms in swimming pool water non-professional users may treat private pools. For disinfection, appropriate balanced water chemistry is required to maintain an adequate active chlorine level. The active chlorine (free chlorine) disinfectant is used to sanitize, i.e. to kill disease-causing organisms, and to oxidize, i.e. to destroy ammonia, nitrogen-containing contaminants and swimmer waste. A stabilizer in outdoor pools influences the active chlorine level by reducing the chlorine dissipation and in this way, the chlorine level is stabilized i.e. consistent. Furthermore, the pH of the pool water should measure between 7.2 and 7.8 to maintain an ample active chlorine level. Additionally, total alkalinity (amount of alkaline substances) in the pool buffers the water against sudden changes in the pH.
Note: if ‘chlorine’ is stated, this refers to ‘active (free) chlorine’
A considerable number of disinfectant products is authorized7) to control micro-organisms and/ or algae. Most of these products are chlorine products in the form of tablets and granules.
Calcium hypochlorite is available as granules or tablets and besides the control of micro-organisms it is also used to clear the pool of algae (see Table 13). When used in an outdoor pool sunlight degrades some of the free (active) chlorine and it is difficult to maintain an adequate chlorine level. When only calcium hypochlorite is used, the pool water is unstabilized. In order to reduce chlorine dissipation, calcium hypochlorite is combined with a stabilizer i.e. cyanuric acid which can be added separately.
Cyanuric acid is also supplied as ingredient in stabilized chlorine granules or tablets such as trichloride isocyanuric acid (TCCA) and sodium dichloride isocyanuric acid (DCCNa). These products maintain consistent levels of chlorine in outdoor pool water, but they also make the chlorine less effective i.e. a higher cyanuric acid level requires a higher minimum free chlorine level. It is therefore necessary not to get too much cyanuric acid in the water. When the cyanuric level is too high, the pool water should be refreshed. Both stabilized chlorine products DCCNa and TCCA add chlorine (sanitizer) as well as cyanuric acid (stabilizer) to the water. TCCA is a slowly dissolving disinfectant and DCCNa is a more quickly dissolving disinfectant.
To maintain the water quality and to prevent algae growth (and bloom), outdoor pools may also require a dose of algaecide (liquid). In case of visible algae (greenish water), one has to treat the pool water with a calcium hypochlorite shock i.e. a high dose to clear the algae; subsequently, an amount algeacide can be added. Algae spores are introduced into the pool through the air, from rainwater and from grass. An algae control product can be applied to swimming pool water that will not be used and chlorinated for a long while (winter period).
In summary, to disinfect an outdoor pool during the swimming season the following products may be required:
- -
DCCNa or TCCA (stabilized chlorine disinfectants) plus algaecides
- -
Calcium hypochlorite (unstabilized chlorine disinfectant) in combination with cyanuric acid (stabilizer) plus algaecides
It is recommended to add chlorine during the evening so that it can act onto micro-organisms, algae and other contaminations; during the day most of the chlorine in an outdoor pool is degraded by UV in sunlight39).
CTB register7) for disinfectants of water includes swimming water, private baths, therapeutic baths, circulation baths, outdoor swimming water and indoor circulation swimming water. In 2004, the registered disinfectant agents for swimming water are restricted to active substances (a.s.) as mentioned in Table 13.
Table 13
Application of active substances in swimming pool disinfectants.
Swimming pool size
Product information over private swimming pools gives a volume ranging from 14 to 52 m3. It is assumed that a private swimming pool measures 8 m × 4 m × 1.5 m, which gives a water surface area of 32 m2 and a volume of 48 m3.
By applying various disinfectant agents, the user maintains the pool. Mixing and loading and subsequently the application of liquids, granules and of tablets are described in section 6.2, section 6.3 and section 6.4, respectively. Post-application exposure describes dermal exposure during swimming in a private pool (section 6.5).
Note
This fact sheet considers disinfectant products applied by consumers (non-professionals). The description of the exposure during swimming in public pools does strictly speaking not belong to this fact sheet. Therefore, the exposure in a public pool is described in the appendix, which is done for three different groups of the population, i.e. baby swimmers, child swimmers and competitive swimmers.
6.2. Liquids
Use
All liquid swimming pool disinfectants in the CTB register7) for the Dutch situation are products to control algae. This type of disinfectant can only be applied to inhibit algae growth and it is not appropriate to control micro-organisms (see Table 13).
The dosing rate is given in ml per m3 of swimming pool water. The used amount of algae control depends on the water condition in the swimming pool, active chlorine level and the concentration of the active substance in the algaecide.
In the following example, the instructions for use stated that an initial treatment of 30 ml/ m3 is required i.e. to prevent algae growth at the start of the swimming season. After that, a maintenance dose of 8 ml/ m3 during the swimming season is needed every 5–7 days. After rainfall, the same dose is additionally applied.
In case of visible algae (greenish water), after shock treatment, an amount of 53 ml algeacide/m3 can be added (see introduction).
To condition the pool water during winter (off-season), the same dose algaecides can be used which is the case when maintenance stops for maximal 3 weeks and the concentration of chlorine compound is below 0.1 mg/L.
Direction for use stated that the required amount of algaecide should be diluted with water in a bucket; subsequently it should be added slowly into a skimmer or distributed evenly around the pool39). A skimmer is an outlet bin situated at the surface of the swimming pool where floating particles on the water will easily be removed; via the skimmer pool water circulates to the pump. During dosing the diluted liquid, the pump should be at work to disperse the formulation in the pool water. Preferably dosing algaecides should be done in the evening, so that it can act onto algae and there is no one swimming in the pool.
Scenario
The scenario describes a private user who is sanitizing an outdoor pool of 48 m3 every 5 days for a period of 4 months. To prevent algae growth the private user pours the required amount of liquid formulation in a bucket and dilutes it 10 times with water; subsequently, the user distributes the dilution evenly around the pool surface (32 m2) during 5 minutes. The dosage is set at 8 ml formulation/ m3; the liquid disinfectant amount required to control algae in a swimming pool can be calculated as dosage (ml/ m3) × 48 m3 (volume swimming pool).
The active substances used to control algae are assumed to be non-volatile due to their salt character. Therefore, it is assumed that the inhalation exposure to algaecides is negligible and it is not described in this section. When another active substance is under consideration, possibility of inhalation exposure should be carefully checked.
To calculate the dermal exposure of the private user the ‘instant application’ model is used during mixing and loading as well as during application.
General
- FrequencyFor the maintenance ration, the dosage is every 5 days for a period of 4 months. It is assumed that before, during and after the winter period i.e. during the off-season, a higher dose is applied (see use). As a result, the frequency is 28 times a year.
Mixing and loading
For the defaults for mixing and loading a liquid, see section 2.2.1.
Application
Dermal exposure: instant application
- Product amountThere is no data available. The distribution of the diluted liquid with a bucket can be more or less compared to emptying a volume container (10 L) of unspecified design during ‘mixing and loading’, which is described in the model UK POEM13). The contamination of emptying a 10 L container is 0.50 ml formulation per operation. In this case, the contamination is set at 0.5 g of diluted formulation (density 1 g/cm3) during emptying the bucket.
- Weight fractionThe dilution is set at 10 times and so, the weight fraction should be divided by 10.
Defaults
Default values algae control liquids: mixing and loading liquid
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 28 year−1 | 2 | See above |
| Dermal | |||
| Exposure, instant application | |||
| Exposed area | 215 cm2 | 3 | One palm: ¼ area hands3) |
| Product amount | 0.01 g | 3 | See section 2.2.1 |
| Uptake, diffusion through skin | |||
| Exposure time | 3 min | 2 | See section 2.2.1 |
Default values for application algae control liquid, swimming pool
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 28 year−1 | 2 | See above |
| Dermal | |||
| Exposure, instant application | |||
| Exposed area | 1900 cm2 | 3 | Area hands3) and forearms; see section 4.3 |
| Product amount dilution | 0.5 g | 2 | See above |
| Weight fraction dilution | Wf / 10 | 2 | See above |
| Uptake: diffusion through skin | |||
| Concentration | Wf / 10 g/cm3 | 2 | Density water 1 g/cm3 |
| Exposure time | 5 min | 2 | See above |
6.3. Granules
Use
In the Netherlands the following authorized disinfectant products (CTB register7)) are available in granules:
- -
calcium hypochlorite
- -
sodium dichlorisocyanuric acid (DCCNa)
- -
cyanuric acid (stabilizer)
The disinfectant calcium hypochlorite is a quickly dissolving non-stabilized disinfectant in granular form (and in tablet form, see Table 13) for continuous disinfection in soft and medium hard water and for shock treatment. For shock treatment a large amount of chlorine (super dose) is added all at once into the pool water to break down accumulated organic wastes and/or kill existing algae and bacteria. The dosage of calcium hypochlorite depends on the presence of a stabilizer such as cyanuric acid or of chlorine products containing cyanuric acid such as TCCA or DCCNa. Cyanuric acid is a stabilizer in order to reduce chlorine dissipation due to UV radiation of the sun. This product should not be used in combination with stabilized disinfectants such as DCCNa and TCCA31). Concentrations over 100 mg/l should be avoided.
DCCNa is a stabilized sanitizer and is a quickly dissolving sanitizer in granular form for shock treatment and continuous disinfection in hard and soft water. In stabilized water the chlorine level should be maintained between 1 and 2 mg/l which depends on the cyanuric acid level (see section 6.1). An example of dosing is given in Table 14.
The required amount of sanitizer should be diluted with water in a bucket; subsequently it should be added slowly into a skimmer or distributed evenly around the pool. During dosing the diluted liquid, the pump should be at work to disperse the formulation in the pool water. Preferably dosing disinfectants should be done in the evening, so that it can act onto contaminants and there is no one swimming in the pool.
Table 14
Example of dosage granules.
Scenario
The scenario describes a private user who applies disinfectant granules to sanitize an outdoor pool of 48 m3 with stabilized water. Once a day for a period of 4 months, the private user dissolves the required amount of granules in a bucket and dilutes it 20 times with water; subsequently, the user distributes the dilution evenly around the pool surface (32 m2) during 5 minutes. The dosage is set at 3 g of granules per m3 of water. The granules amount required to disinfect the water can be calculated as dosage (g/m3) × 48 m3 (volume swimming pool).
To calculate the dermal exposure of the private user the ‘constant rate’ model is used during ‘mixing and loading’ and the ‘instant application’ model during application.
General
- FrequencyThe dosage is once a day for a period of 4 months i.e. 122 times per year.
Mixing and loading
For the defaults for mixing and loading granules, see section 2.2.2.
Application
Dermal exposure: instant application
- Weight fractionThe dilution is set at 20 times and so, the weight fraction should be divided by 20.
Defaults
Default values for mixing and loading, dissolving granules
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 122 year−1 | 2 | See above |
| Dermal | |||
| Exposure, constant rate | |||
| Contact rate | 0.033 mg/ min | 2 | See section 2.2.2 |
| Release duration | 1.33 min | 3 | See section 2.2.2 |
| Uptake, fixed fraction | |||
| Uptake fraction | 1 | 2 | Potential dose |
Default values for application granules, swimming pool
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 122 year−1 | 2 | See above |
| Dermal | |||
| Exposure, instant application | |||
| Exposed area | 1900 cm2 | 3 | Area hands3) and forearms; see section 4.3 |
| Product amount dilution | 0.5 g | 2 | See section 6.2 |
| Weight fraction dilution | Wf / 20 | 2 | See above |
| Uptake: diffusion through skin | |||
| Concentration | Wf / 20 | 2 | Density water 1 g/cm3 |
| Exposure time | 5 min | 2 | See above |
6.4. Tablets
Use
In the Netherlands the following authorized disinfectant products (CTB register7)) are available in tablets:
- -
calcium hypochlorite
- -
trichloride isocyanuric acid (TCCA)
The disinfectant calcium hypochlorite is available as non-stabilized sanitizer tablets (20 g) for continuous disinfection in soft and medium hard water and for shock treatment.
As stabilized sanitizer TCCA is used. It is a slowly dissolving sanitizer in tablet form (20 g or 200 g) and the dosage may vary widely (sunlight, bathing-load etc.). These tablets are used to maintain a constant chlorine level in the pool water. An example of dosing is given in Table 12. The chlorine level should be between 1 and 2 ppm (stabilized water) which depends on the cyanuric acid level (see section 6.1).
Slowly dissolving tablets are put into a floating dispenser and the release rate can be adjusted by opening or closing the bottom collar. During releasing the active substance via the floating dispenser into the pool water, the pump should be at work to disperse the formulation in the pool water. During swimming the pump should not be working and the floating dispenser should be removed. TTCA tablets can also be placed into the skimmer (outlet bin) to dissolve over several days39).
Table 15
Example of dosage tablets.
Scenario
The scenario describes a private user who applies disinfectant tablets to sanitize an outdoor pool of 48 m3 with stabilized water. Every day for a period of 4 months, the private user dissolves ten tablets of 20 grams (Ca hypochlorite) in a bucket and dilutes it 20 times with water; subsequently, the user distributes the dilution evenly around the pool surface (32 m2) during 5 minutes.
To calculate the dermal exposure of the private user the ‘constant rate’ model is used during mixing and loading.
General
- FrequencyTen tablets of 20 g is used every days during 4 months, which gives a frequency of 122 times a year.
Mixing and loading
For the defaults for mixing and loading tablets, see section 2.2.3.
Defaults
Default values for mixing and loading, dissolving tablets
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 122 year−1 | 2 | See above |
| Dermal | |||
| Exposure, constant rate | |||
| Contact rate | 0.033 mg/ min | 2 | See section 2.2.3 |
| Release duration | 1 min | 1 | 10 tablets; see section 2.2.3 |
| Uptake, fixed fraction | |||
| Uptake fraction | 1 | 2 | Potential dose |
Default values for application tablets, swimming pool
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 122 year−1 | 2 | See above |
| Dermal | |||
| Exposure, instant application | |||
| Exposed area | 1900 cm2 | 3 | Area hands3) and forearms; see section 4.3 |
| Product amount dilution | 0.5 g | 2 | See section 6.2 |
| Weight fraction dilution | Wf / 20 | 2 | See above |
| Uptake: diffusion through skin | |||
| Concentration | Wf / 20 | 2 | Density water 1 g/cm3 |
| Exposure time | 5 min | 2 | See above |
6.5. Post application
Scenario
The scenario describes a private user who swims in a private outdoor pool of 48 m3. Three times a week during a period of 4 months, the user swims for 60 minutes per event.
Generally, active substances used to sanitize swimming pools are assumed to be non-volatile due to their salt character. Further, the inhalation exposure in outdoor pools will be negligible, as atmospheric concentrations of volatile by-products such as trihalomethanes (e.g. chloroform) above the pool water surface are very low, even when their concentrations in water are high. Modelling and measurements in outdoor pools demonstrate low concentrations of volatile organic chemicals in proximity to outdoor pools.32)
To calculate the exposure of the user during swimming the ‘constant rate’ model is used for both dermal exposure and oral exposure.
Dermal and oral exposure
- FrequencyDuring a period of 4 months the user swims 3 times a week i.e. 52 times a year.
- Exposure timeFor exposure time a default value of 60 min is used for both dermal uptake (diffusion through skin) and oral exposure.
- Weight fractionThe weight fraction is the calculated weight fraction of the active substance in the swimming pool water.
- ConcentrationThe concentration (g/cm3) is the calculated weight fraction of the active substance in the swimming pool water (density water 1 g/cm3).
Dermal exposure: instant application
- Exposed areaThe exposed area of the body3) is 17 500 cm2.
- Product amountIt is assumed that not the total amount of swim water is in contact with the skin but only a layer of 1 cm around the exposed skin; thus, the amount of swim water is 17500 cm3. The default value for amount (diluted) product is set at 17500 grams.
Oral exposure: constant rate
- Ingestion rateAccording to the Standard Operating Procedures for swimming pools34), the assumed mean ingestion rate for adults is 50 ml/hr. Different WHO reports stated different ingestion rates. WHO35) gives an assumed volume of water ingestion of 20 to 50 ml water per hour of swimming. WHO32) gives for an adult swimmer and for a competitive swimmer an ingestion rate of 50 and 225 ml/hr, respectively. Moreover, WHO36) indicates an amount of 100 ml consuming per event. Using these data, the default value for ingestion rate is set at 50 ml/hr or 830 mg/min (density 1 g/cm3).
Default post-application swimming pool disinfectants; outdoor private swimming pool
| Default value | Q | References, comments | |
|---|---|---|---|
| General | |||
| Frequency | 52 year−1 | 2 | See above |
| Dermal | |||
| Exposure, instant application/ | |||
| Exposed area | 17500 cm2 | 4 | 3) |
| Product amount dilution | 17500 g | 1 | See above |
| Uptake: diffusion through skin | |||
| Exposure time | 60 min | 2 | See above |
| Oral | |||
| Exposure, constant rate | |||
| Ingestion rate | 830 mg/ min | 1 | See above |
| Exposure time | 60 min | 2 | See above |
| Uptake, fixed fraction | |||
| Uptake fraction | 1 | 2 | Potential dose |
- Swimming pool disinfectants - Disinfectant Products Fact Sheet: To assess the ri...Swimming pool disinfectants - Disinfectant Products Fact Sheet: To assess the risks for the consumer
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