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EC number: 231-959-5 | CAS number: 7782-50-5
- 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

Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
Description of key information
Read-across from sodium hypochlorite (justification see IUCLID5 section 6.1 or CSR section 7.1.1):
The respiration inhibition in activated sludge started with the addition of 0.37 mg/L Cl2 and reached 100% at the addition of 37 mg/L Cl2.
The EC50 was determined to be 3 mg/L Cl2.
Since chlorine is reacting readily with organic compounds and with the ammonium in the sewage, under real conditions, an impairment of the purification efficiency of treatment plants should not be expected.
Key value for chemical safety assessment
- EC50 for microorganisms:
- 3 mg/L
Additional information
Read-across from sodium hypochlorite (justification see IUCLID5 section 6.1 or CSR section 7.1.1):
Despite the strong antimicrobial potential of hypochlorite, concern for inhibition effects on biological sewage treatment at the current hypochlorite utilization pattern is undue. Activated sludge flocs are not very sensitive to NaClO, probably due to protection by their glycocalix made out of polysaccharides.
The EC50 for the inhibition of activated sludge respiration is situated around 3000 μg/l for a continuous hypochlorite dosage, with a LOEC of ca. 375 μg/l (Raff et al., 1987). The sludge concentration used and the pH were not mentioned in the paper. The result obtained is very much dependent on the sludge concentration used (i.e. the organic content in the test vessel). Therefore the figure mentioned is just a figure and different data will be obtained using different sludge concentrations. Also different pH values will probably generate different data. The tentative LOEC of 375μg/l derived by the authors should only be used as an indication for potential effects on a sewage treatment plant with the limitations mentioned before (Raff et al., 1987).
Marstaller et al. (Environmental Technology, 13, 1077 -1084, 1992) reported a decrease of nitrifying activity as of batch doses of 1500 μg NaClO/mg sludge suspended solids, but they mention also that chlorine is commonly used in Sewage Treament Plants as a mean to control proliferation of filamentous bacteria, that increase Sludge Volume Index (poor settleability).
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