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EC number: 231-668-3 | CAS number: 7681-52-9
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data

Ecotoxicological Summary
Administrative data
Hazard for aquatic organisms
Freshwater
- Hazard assessment conclusion:
- PNEC aqua (freshwater)
- PNEC value:
- 0.21 µg/L
- Assessment factor:
- 10
- Extrapolation method:
- assessment factor
- PNEC freshwater (intermittent releases):
- 0.26 µg/L
Marine water
- Hazard assessment conclusion:
- PNEC aqua (marine water)
- PNEC value:
- 0.042 µg/L
- Assessment factor:
- 50
- Extrapolation method:
- assessment factor
STP
- Hazard assessment conclusion:
- PNEC STP
- PNEC value:
- 4.69 mg/L
- Assessment factor:
- 100
- Extrapolation method:
- assessment factor
Sediment (freshwater)
- Hazard assessment conclusion:
- no exposure of sediment expected
Sediment (marine water)
- Hazard assessment conclusion:
- no exposure of sediment expected
Hazard for air
Air
- Hazard assessment conclusion:
- no hazard identified
Hazard for terrestrial organisms
Soil
- Hazard assessment conclusion:
- no exposure of soil expected
Hazard for predators
Secondary poisoning
- Hazard assessment conclusion:
- PNEC oral
- PNEC value:
- 11.1 mg/kg food
- Assessment factor:
- 90
Additional information
The PNEC´s were derived from the most sensitive test available for each relevant compartment/endpoint.
For information: naming rules and conversion factors for different types of concentration given for sodium hypochlorite/chlorine:
“Available chlorine” corresponds to ion ClO- and to gases HOCl and Cl2 dissolved in water. It is the oxidizing potential corresponding to the double of chlorine quantity as NaOCl in a concentrated alkaline solution.
“Active chlorine” corresponds to to gases HOCl and Cl2 dissolved in water for neutral or acidic diluted solutions.
“Total chlorine” corresponds to all species of chlorine in solution: hypochlorite, sodium chloride, chlorites ClO2- and chlorates ClO3-.
Active chlorine (a.c.) can be given in percentage (w/w) or in g/L (w/v). Conversion from one to another requires density of the solution:
Y% a.c.= X g/L a.c./(d x 10)
Concentration of sodium hypochlorite can be calculated from % a.c. as follows:
MW a.c. (as Cl2) = 71
MW NaOCl = 74.5
% NaOCl = % a.c. x (74.5/71) = % a.c. x 1.05
Formerly, in certain countries, use was made of chlorometric degrees (°chl.). It corresponds to the minimal gaseous chlorine used for preparation of bleach, in litres of Cl2 for 1 litre of bleach.
Example: 71 g a.c. corresponds to 22.4 L, so 1L concentrated bleach at 9.6 %a.c. contains 110.56 g a.c.. To produce it, 110.56 x (22.4/71) = 34.88 L of chlorine were necessary, hence: 34.88 °chl.
A number of terms can be used to describe chlorine in water, such as ‘free’, ‘active’, ‘available’, ‘combined’ and ‘residual’ chlorine. The following definitions are commonly used:
- Free available chlorine (FAC) is the concentration of chlorine available in a mixture, at equilibrium, of hypochlorous acid and the hypochlorite ion. It is the form in which it is available to act as an oxidant.
- Combined available chlorine (CAC) is the available chlorine as chloramines or other N-Cl linked compounds.
- Total residual/available chlorine (TR/AC) (the terms total residual and total available chlorine can be used interchangeably) relates to the sum of the FAC and CAC.
- Total residual oxidant (TRO) is the sum of all oxidants including non-chlorine species. In water containing bromine, such as seawater, there is displacement of chlorine by bromine resulting in hypobromous acid, hypobromite ions and bromamines. Some authors also mention CPO (chlorine produced oxidants).
Conclusion on classification
Classification of sodium hypochlorite solutions and mixtures according to CLP
1. Acute environmental toxicity
High quality studies concerning the acute toxicity of sodium hypochlorite to algae and aquatic invertebrates have recently been carried out in order to upgrade the data set available, in the frame of the substance dossiers submitted under REACH and the Biocidal Products Regulation (BPR). Relevant studies are summarised in Table 1.
Table 1. Summary of acute toxicity data for sodium hypochlorite
Year |
Author |
Test details |
Test organism |
Result |
2013 |
Liedtke |
freshwater |
Pseudokirchneriella subcapitata (Algae) |
ErC50= 0.0499 mg (nominal)/L ErC50= 0.0365 mg (initial measured)/L
|
1984 |
Watkins |
freshwater |
Myriophyllum spicatum (freshwater vascular plant) |
ErC50= 0.1 mg/L
|
2009 |
Gallagher |
short-term, freshwater |
Daphnia magna |
EC50-48h = 0.141 mg/L
|
2011 |
Gallagher |
short term, freshwater |
Ceriodaphnia dubia |
EC50-48h = 0.035 mg/l
|
1978 |
Roberts |
short-term, saltwater invertebrate |
Crassostrea virginica (oyster) |
LC50= 0.026 mg/L
|
1978 |
Heath |
short-term, freshwater |
Fish |
LC50= 0.06 mg/L
|
1978 |
Thatcher |
short-term, saltwater |
Fish |
LC50= 0.032 mg/L
|
The above data shows that algae, invertebrates and fish are equally sensitive to the toxic effects of sodium hypochlorite and this allows us to conclude that the acute toxicity of sodium hypochlorite to marine and freshwater species lies in the range:0.01 < L(E)C50≤ 0.1 mg/L.With respect to classification rules defined in Annex I, Table 4.1.3 of Regulation (EC) No. 1272/2008 (CLP), concerning multiplying factors for highly toxic components of mixtures,this means that an “M-factor” of 10 should be assigned to sodium hypochlorite with regards to acute toxicity classification.
Sodium hypochlorite is produced as an aqueous solution. According to Table 4.1.1 of the Regulation (EC) No. 1272/2008, pure solutions (i.e. dilutions in water) or mixtures have to be classified depending on the concentration of active chlorine. A proposed classification based on concentration limits is shown below in Table 3. as shown in Table 3. For mixtures, the acute M-Factor = 10 has to be used unless test data for the complete mixture or similar mixtures are available at the formulator level, as described in Figure 4.1.2 of the regulation. Where test data is available, classification of a mixture derived using test data for the complete mixture or similar mixtures will take precedence over classification derived from calculation.
2. Chronic environmental toxicity
The 2nd Adaptation to Progress of the CLP regulation (EC 286/2011) of 10 March 2011 further modified the classification criteria for aquatic chronic toxicity. This means that for substances, as well as for mixtures, aquatic chronic toxicity data are taken into account for long-term hazard classification. The key studies for chronic aquatic toxicity of sodium hypochlorite are presented in Table 2.
Table 2. Summary of chronic toxicity data for sodium hypochlorite
Year |
Author |
Test details |
Test organism |
Result |
2013 |
Liedtke |
freshwater |
Algae (Pseudokirchneriella subcapitata) |
ErC10= 0.0299 mg (nominal)/L, NOECr = 0.0171 mg (nominal)/L ErC10= 0.0199 mg (initial measured)/L, NOECr = 0.0054 mg (initial measured)/L
|
1990 |
Cairns |
long-term, freshwater |
Algae (periphyton) |
NOEC (7 d) = 0.0021 mg/L |
1978 |
Liden |
long-term, marine water |
Oyster |
NOEC (7 d) = 0.007 mg/L |
1983 |
Goodman |
long-term, marine water |
Fish |
NOEC (28 d) = 0.04 mg/ |
The above results show NOEC values between 0.002 and 0.04 mg/l, as active chlorine. According to Table 4.1.0 (b)(ii) of the CLP Regulation, as a rapidly degradable substance, a classification as Chronic Category 1 (H410, very toxic to aquatic life with long lasting effects) applies to sodium hypochlorite solutions. Furthermore, using Table 4.1.3, concerning multiplying factors for highly toxic components of mixtures, an “M-factor” of 1 has to be assigned to sodium hypochlorite with regards to chronic toxicity (0,001 < NOEC£0,01; RD component).
3. Proposed classification for environmental toxicity of sodium hypochlorite according to CLP
For dilutions and mixtures containing sodium hypochlorite, provided there is no other component classified as hazardous to the aquatic environment, the proposed classification for acute and chronic toxicity of sodium hypochlorite is outlined in Tables 3 & 4. This proposal is based on the key studies and discussion above and taking into consideration the classification criteria set down in Regulation (EC) No. 1272/2008.
Table 3. Proposed acute environmental classification
Concentration of sodium hypochlorite solutions (as % active chlorine) |
Acute Classification |
H Statements |
M Factor |
≥ 2.5 % |
Acute Category 1 |
H400 (very toxic to aquatic life) |
10 |
< 2.5 % |
None |
None |
N/A |
Table 4. Proposed chronic environmental classification
Concentration of sodium hypochlorite solutions (as % active chlorine) |
Chronic Classification |
H Statements |
M Factor |
≥ 25 %. |
Chronic Category 1 |
H410 (very toxic to aquatic life with long lasting effects) |
1 |
< 25 % but ≥ 2.5 % |
Chronic Category 2 |
H411 (toxic to aquatic life with long lasting effects) |
N/A |
< 2.5 % but ≥ 0.25 %. |
Chronic Category 3 |
H412 (harmful to aquatic life with long lasting effects) |
N/A |
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