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EC number: 233-666-8 | CAS number: 10294-66-3
- 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
![](https://chesar.echa.europa.eu/o/diss-blank-theme/images/factsheets/A-REACH/factsheet/print_ecotoxicological-information.png)
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
- Endpoint:
- toxicity to microorganisms
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Acceptable well documented study which meets basic scientific principles.
- Justification for type of information:
- see attachment “Read-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
- Principles of method if other than guideline:
- growth inhibition test using a mixture of aerobic bacteria
- GLP compliance:
- no
- Analytical monitoring:
- no
- Vehicle:
- no
- Test organisms (species):
- other: other bacteria: mixed cultures
- Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 16 h
- Duration:
- 16 h
- Dose descriptor:
- IC50
- Effect conc.:
- 2 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Remarks:
- based on turbidity measurements
- Endpoint:
- toxicity to microorganisms
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- supporting study
- Study period:
- 1988-07-29
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Non-GLP Guideline study without analytical verification of test concentrations
- Justification for type of information:
- see attachment “Read-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
- Qualifier:
- according to guideline
- Guideline:
- DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)
- GLP compliance:
- no
- Analytical monitoring:
- no
- Vehicle:
- no
- Details on test solutions:
- PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The stock solution was prepared dissolving 1250 mg of the test substance in 1 l of deionized water. From the stock solution 9 concentrations were prepared through 1:2 dilution steps. - Test organisms (species):
- Pseudomonas putida
- Details on inoculum:
- - Laboratory culture: Pseudomonas putida regularly obtained from DSM (German collection of microorganisms, Goettingen, Germany)
- strain: DSM 50026
- Pre-culture:
- Test vessel: Erlenmeyer flasks, volume 300 mL, fill volume 100 mL
- inoculated with bacterial suspension at a turbidity of 10 TE/F at 21 ± 1 °C
- incubation time: 7 hours, shaking
- nutrient medium: AK-Medium, DIN 38412 Part 8 - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 17 h
- Test temperature:
- 20°C
- pH:
- test start: 5.3 - 7.0 mg/L
test end: 4.6 - 7.0 mg/L (inoculated)
test end: 4.7 - 7.2 mg/L (without inoculum) - Dissolved oxygen:
- test start: 5.0 - 9.2 mg/L
test end: 0.3 - 8.8 mg/L (inoculated)
test end: 8.8-8.9 mg/L (without inoculum) - Nominal and measured concentrations:
- 0, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, 1000 mg/L
- Details on test conditions:
- TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): Penicillium vessel with flattened bottom, plugged with silicone sponge caps
- Material, fill volume: glass, 10 mL
- Aeration: no
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: nutrient medium: 0.5 g/L Sodium nitrate, 0.12 g/L dipotassium hydrogen phosphate, 0.06 g/L Potassium dihydrogen phosphate, 0.2 g/L magnesium sulphate heptahydrate, 2.0 g/L D(+)-Glucose, 0.0005 g/L ferric citrate
EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Photometric determination of light extinction at 436 nm after 17 hours of exposure
- pH and oxygen was measured at test start end test end in inoculated samples and blank medium, respectively. - Duration:
- 17 h
- Dose descriptor:
- other: EC90
- Effect conc.:
- 115.1 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Duration:
- 17 h
- Dose descriptor:
- EC10
- Effect conc.:
- 30.8 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Duration:
- 17 h
- Dose descriptor:
- EC50
- Effect conc.:
- 56.1 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Conclusions:
- A growth inhibition test with the micro-organism Pseudomonas putida was conducted, following standard guidelines (non-GLP). Reported 17h-EC50 and EC10 were 56.1 and 30.8 mg test substance/L, respectively. Data can be used as supporting information for the micro-organisms effects assessment of disodium disulfite and other sulfite compounds (read-across principle).
- Endpoint:
- toxicity to microorganisms
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Study period:
- 1988-07-21
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Non-GLP Guideline study without analytical verification of test concentrations
- Justification for type of information:
- see attachment “Read-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
- Qualifier:
- according to guideline
- Guideline:
- DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)
- GLP compliance:
- no
- Analytical monitoring:
- no
- Vehicle:
- no
- Details on test solutions:
- PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The stock solution was prepared dissolving 1250 mg of the test substance in 1 l of deionized water. From the stock solution 9 concentrations were prepared through 1:2 dilution steps. - Test organisms (species):
- Pseudomonas putida
- Details on inoculum:
- - Laboratory culture: Pseudomonas putida regularly obtained from DSM (German collection of microorganisms, Goettingen, Germany)
- strain: DSM 50026
- Pre-culture:
- Test vessel: Erlenmeyer flasks, volume 300 mL, fill volume 100 mL
- inoculated with bacterial suspension at a turbidity of 10 TE/F at 21 ± 1 °C
- incubation time: 7 hours, shaking
- nutrient medium: AK-Medium, DIN 38412 Part 8 - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 17 h
- Test temperature:
- 20°C
- pH:
- test start: 7.0 - 7.9 mg/L
test end: 5.0 - 7.4 mg/L (inoculated)
test end: 7.0 - 7.6 mg/L (without inoculum) - Dissolved oxygen:
- test start: 7.1 - 8.5 mg/L
test end: 0.3 - 5.6 mg/L (inoculated)
test end: 9.0-9.1 mg/L (without inoculum) - Nominal and measured concentrations:
- 0, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, 1000 mg/L
- Details on test conditions:
- TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): Penicillium vessel with flattened bottom, plugged with silicone sponge caps
- Material, fill volume: glass, 10 mL
- Aeration: no
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: nutrient medium: 0.5 g/L Sodium nitrate, 0.12 g/L dipotassium hydrogen phosphate, 0.06 g/L Potassium dihydrogen phosphate, 0.2 g/L magnesium sulphate heptahydrate, 2.0 g/L D(+)-Glucose, 0.0005 g/L ferric citrate
EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Photometric determination of light extinction at 436 nm after 17 hours of exposure
- pH and oxygen was measured at test start end test end in inoculated samples and blank medium, respectively. - Duration:
- 17 h
- Dose descriptor:
- EC10
- Effect conc.:
- 153 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Duration:
- 17 h
- Dose descriptor:
- EC50
- Effect conc.:
- 410 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Conclusions:
- A growth inhibition test with the micro-organism Pseudomonas putida was conducted, following standard guidelines (non-GLP). Reported 17h-EC50 and EC10 were 410 and 153 mg test substance/L, respectively. Data can be used as supporting information for the micro-organisms effects assessment of potassium sulfite and other sulfite compounds (read-across principle).
- Endpoint:
- toxicity to microorganisms
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Study period:
- 1988-07-29
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Non-GLP Guideline study without analytical verification of test concentrations
- Justification for type of information:
- see attachment “Read-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
- Qualifier:
- according to guideline
- Guideline:
- DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)
- GLP compliance:
- no
- Analytical monitoring:
- no
- Vehicle:
- no
- Details on test solutions:
- PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The stock solution was prepared dissolving 1250 mg of the test substance in 1 l of deionized water. From the stock solution 9 concentrations were prepared through 1:2 dilution steps. - Test organisms (species):
- Pseudomonas putida
- Details on inoculum:
- - Laboratory culture: Pseudomonas putida regularly obtained from DSM (German collection of microorganisms, Goettingen, Germany)
- strain: DSM 50026
- Pre-culture:
- Test vessel: Erlenmeyer flasks, volume 300 mL, fill volume 100 mL
- inoculated with bacterial suspension at a turbidity of 10 TE/F at 21 ± 1 °C
- incubation time: 7 hours, shaking
- nutrient medium: AK-Medium, DIN 38412 Part 8 - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 17 h
- Test temperature:
- 20°C
- pH:
- test start: 4.7 - 7.0 mg/L
test end: 4.3 - 7.1 mg/L (inoculated)
test end: 4.6 - 7.2 mg/L (without inoculum) - Dissolved oxygen:
- test start: 5.7 - 9.5 mg/L
test end: 0.5 - 8.8 mg/L (inoculated)
test end: 8.9-9.1 mg/L (without inoculum) - Nominal and measured concentrations:
- 0, 7.81, 15.63, 31.25, 62.5, 125, 250, 500, 1000 mg/L
- Details on test conditions:
- TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): Penicillium vessel with flattened bottom, plugged with silicone sponge caps
- Material, fill volume: glass, 10 mL
- Aeration: no
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: nutrient medium: 0.5 g/L Sodium nitrate, 0.12 g/L dipotassium hydrogen phosphate, 0.06 g/L Potassium dihydrogen phosphate, 0.2 g/L magnesium sulphate heptahydrate, 2.0 g/L D(+)-Glucose, 0.0005 g/L ferric citrate
EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Photometric determination of light extinction at 436 nm after 17 hours of exposure
- pH and oxygen was measured at test start end test end in inoculated samples and blank medium, respectively. - Duration:
- 17 h
- Dose descriptor:
- other: EC90
- Effect conc.:
- 124 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Duration:
- 17 h
- Dose descriptor:
- EC10
- Effect conc.:
- 32 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Duration:
- 17 h
- Dose descriptor:
- EC50
- Effect conc.:
- 65 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- growth inhibition
- Conclusions:
- A growth inhibition test with the micro-organism Pseudomonas putida was conducted, following standard guidelines (non-GLP). Reported 17h-EC50 and EC10 were 64.8 and 32.1 mg test substance/L, respectively. Data can be used as supporting information for the micro-organisms effects assessment of potassium disulfite and other (di-)sulfite compounds (read-across principle).
- Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: OECD 2009-study, conducted under GLP
- Justification for type of information:
- see attachment “Read-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- not required
- Test organisms (species):
- activated sludge of a predominantly domestic sewage
- Details on inoculum:
- A microbial inoculum was used in htis test system. Activated sludge from a sewage treatment plant was used as the microbial inoculum for the test. The activated sludge was obtained from the sewage treatment works in Frankfurt/Main Niederrad treating predominantly domestic sewage.
- Date of sampling/date of arrival at ECT: August 16, 2010
- Washing medium for activated sludge: reconstituted water (OECD 1992)
- Frequency of washing: three times - between washings the activated sludge was centrifuged for 2 min at 1000 rpm
- Storage before use: 4 days
- Storage temperature: 20 +/- 2 degrees Celcius
- pH of the activated sludge: 6.9
- mixed liquor suspended solids level in the microbial inoculum: 4.36 g/L
Reconstituted water according to OECD Guideline No. 203 (Fish, acute toxicity test) was used to wash and to maintain the activated sludge. The reconstituted water contained salts at the following final concentrations: CaCl2.2H2O: 294 mg/L ; MgSO4.7H2O: 123.25 mg/L ; NaHCO3: 64.75 mg/L ; KCl: 5.75 mg/L ; pH: 7.8 ; Hardness: 253.6 mg/L as CaCO3 ; O2-conc.: 9 mg/L. Medium was prepared within one month before use, and was aerated. - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 3 h
- Test temperature:
- 20.0 to 20.2 degrees Celcius (n=29)
- pH:
- pH of activated sludge: 6.9
- Nominal and measured concentrations:
- Definitive test: 5 concentration levels + control
nominal levels: 0, 10, 32, 100, 316 and 1000 mg test item/L - Details on test conditions:
- Preparation of test solutions: Stock solution was prepared by dissolving 1.0003g of the test item in 500 mL of deionised water. Stock solution was stirred on a magnetic stirring device for approx. 5 min and during removal of corresponding amounts of stock solution for preparation of each single test vessel.
- method of administration of the inoculum was based on the requirements of the test guideline
* amount of synthetic sewage feed in test solution: 16 mL
* amount of test solution/concentration: 300 ml
* amount of microbial inoculum added: 200 mL
* total test volume: 500 mL
* mixed liquor suspended solids level in the final test mixtures: 1.74 g/L
- two replicates were used for the control
- vessels were prepared at intervals of 15 minutes, starting with the first control, followed by test item concentration levels and the second control at the end
- before use, vessels were sterilized in a drying oven for three hours at 150 degrees Celcius.
- type of vessel: 1000 mL glass beakers without cover
- one replicate for each concentration level was tested
- aeration of test vessels: 40 to 50 liter of air per hour (ambient air, oil-free air-compressor)
- at the end of the contact time (= test period) the content of the first vessel was poured into the measuring apparatus and the respiration rate was determined. All other test vessels were measured according to this procedure in the same order which was established for the preparation of the test vessels.
Synthetic sewage feed: the following amounts of substances in 1L of deionized water (in g/L) - prepared within 1 week before use:
* peptone: 16
* meat extract: 11
* urea: 3
* NaCl: 0.7
* CaCl2.2H2O: 0.4
* MgSO4.7H2O: 0.2
* K2HPO4: 2.8
Oximeter OXI 530 (WTW GmbH, D-82362 Weilheim) was used to determine the oxygen content of the test solutions. Oxygen measurements were taken at intervals of two seconds for up to 10 minutes at the end of the contact period for the content of each test vessel - Reference substance (positive control):
- yes
- Remarks:
- 3,5-dichlorophenol
- Duration:
- 3 h
- Dose descriptor:
- NOEC
- Effect conc.:
- >= 1 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Remarks:
- respiration rate
- Duration:
- 3 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 1 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Remarks:
- respiration rate
- Details on results:
- The control respiration rates did not differ more than 15% compared to each other, i.e., only 2.9%
- Results with reference substance (positive control):
- The 3h-EC50 of 3,5-dichlorophenol was in the accepted range of 5 to 30 mg/L, i.e., 10.0 mg/L
- Reported statistics and error estimates:
- Respiration rate was calculated from the oxygen consumption of the test solutions as mg O2/L between 6.5 and 2.5 mg O2/L.
The portion of the respiration curve over which the respiration rate was measured was linear.
Respiration rate was expressed as percentage of the mean of the two control respiration rates, thus allowing to determine ECx values
Weibull Analysis was used to determine the ECx values. The statistical software package ToxRat 2.10 Professional (ToxRat Solutions GmbH, Naheweg 15, D-52477 Alsdorf) was used for these calculations - Validity criteria fulfilled:
- yes
- Conclusions:
- An OECD No. 209 was performed, using ammonium thiosulfate as test substance. The test was conducted under GLP. Inhibition of respiration rate after a 3h-exposure period was evaluated. No significant adverse effects were noted up to the highest test concentration of 1000 mg/L, resulting in a NOEC value equal or higher than 1000 mg test substance/L .
Data can be used for the effects assessment of ammonium thiosulfate and other thiosulfate compounds (read-across principle) - Endpoint:
- activated sludge respiration inhibition testing
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- weight of evidence
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: OECD 2009-study, conducted under GLP
- Justification for type of information:
- see attachment “Read-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
- GLP compliance:
- yes (incl. QA statement)
- Analytical monitoring:
- not required
- Test organisms (species):
- activated sludge of a predominantly domestic sewage
- Details on inoculum:
- A microbial inoculum was used in htis test system. Activated sludge from a sewage treatment plant was used as the microbial inoculum for the test. The activated sludge was obtained from the sewage treatment works in Frankfurt/Main Niederrad treating predominantly domestic sewage.
- Date of sampling/date of arrival at ECT: August 16, 2010
- Washing medium for activated sludge: reconstituted water (OECD 1992)
- Frequency of washing: three times - between washings the activated sludge was centrifuged for 2 min at 1000 rpm
- Storage before use: 4 days
- Storage temperature: 20 +/- 2 degrees Celcius
- pH of the activated sludge: 6.9
- mixed liquor suspended solids level in the microbial inoculum: 4.36 g/L
Reconstituted water according to OECD Guideline No. 203 (Fish, acute toxicity test) was used to wash and to maintain the activated sludge. The reconstituted water contained salts at the following final concentrations: CaCl2.2H2O: 294 mg/L ; MgSO4.7H2O: 123.25 mg/L ; NaHCO3: 64.75 mg/L ; KCl: 5.75 mg/L ; pH: 7.8 ; Hardness: 253.6 mg/L as CaCO3 ; O2-conc.: 9 mg/L. Medium was prepared within one month before use, and was aerated. - Test type:
- static
- Water media type:
- freshwater
- Limit test:
- no
- Total exposure duration:
- 3 h
- Test temperature:
- 20.0 to 20.2 degrees Celcius (n=29)
- pH:
- pH of activated sludge: 6.9
- Nominal and measured concentrations:
- Definitive test: 5 concentration levels + control
nominal levels: 0, 10, 32, 100, 316 and 1000 mg test item/L - Details on test conditions:
- Preparation of test solutions: Stock solution was prepared by dissolving 1.0003g of the test item in 500 mL of deionised water. Stock solution was stirred on a magnetic stirring device for approx. 5 min and during removal of corresponding amounts of stock solution for preparation of each single test vessel.
- method of administration of the inoculum was based on the requirements of the test guideline
* amount of synthetic sewage feed in test solution: 16 mL
* amount of test solution/concentration: 300 ml
* amount of microbial inoculum added: 200 mL
* total test volume: 500 mL
* mixed liquor suspended solids level in the final test mixtures: 1.74 g/L
- two replicates were used for the control
- vessels were prepared at intervals of 15 minutes, starting with the first control, followed by test item concentration levels and the second control at the end
- before use, vessels were sterilized in a drying oven for three hours at 150 degrees Celcius.
- type of vessel: 1000 mL glass beakers without cover
- one replicate for each concentration level was tested
- aeration of test vessels: 40 to 50 liter of air per hour (ambient air, oil-free air-compressor)
- at the end of the contact time (= test period) the content of the first vessel was poured into the measuring apparatus and the respiration rate was determined. All other test vessels were measured according to this procedure in the same order which was established for the preparation of the test vessels.
Synthetic sewage feed: the following amounts of substances in 1L of deionized water (in g/L) - prepared within 1 week before use:
* peptone: 16
* meat extract: 11
* urea: 3
* NaCl: 0.7
* CaCl2.2H2O: 0.4
* MgSO4.7H2O: 0.2
* K2HPO4: 2.8
Oximeter OXI 530 (WTW GmbH, D-82362 Weilheim) was used to determine the oxygen content of the test solutions. Oxygen measurements were taken at intervals of two seconds for up to 10 minutes at the end of the contact period for the content of each test vessel - Reference substance (positive control):
- yes
- Remarks:
- 3,5-dichlorophenol
- Duration:
- 3 h
- Dose descriptor:
- NOEC
- Effect conc.:
- >= 1 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Remarks:
- respiration rate
- Duration:
- 3 h
- Dose descriptor:
- EC50
- Effect conc.:
- > 1 000 mg/L
- Nominal / measured:
- nominal
- Conc. based on:
- test mat.
- Basis for effect:
- inhibition of total respiration
- Remarks:
- respiration rate
- Details on results:
- The control respiration rates did not differ more than 15% compared to each other, i.e., only 0.6%
- Results with reference substance (positive control):
- The 3h-EC50 of 3,5-dichlorophenol was in the accepted range of 5 to 30 mg/L, i.e., 10.0 mg/L
- Reported statistics and error estimates:
- Respiration rate was calculated from the oxygen consumption of the test solutions as mg O2/L between 6.5 and 2.5 mg O2/L.
The portion of the respiration curve over which the respiration rate was measured was linear.
Respiration rate was expressed as percentage of the mean of the two control respiration rates, thus allowing to determine ECx values
Weibull Analysis was used to determine the ECx values. The statistical software package ToxRat 2.10 Professional (ToxRat Solutions GmbH, Naheweg 15, D-52477 Alsdorf) was used for these calculations - Validity criteria fulfilled:
- yes
- Conclusions:
- An OECD No. 209 was performed, using sodium sulfite as test substance. The test was conducted under GLP. Inhibition of respiration rate after a 3h-exposure period was evaluated. No significant adverse effects were noted up to the highest test concentration of 1000 mg/L, resulting in a NOEC value equal or higher than 1000 mg test substance/L .
Data can be used for the effects assessment of sodium sulfite and other (di-)sulfite compounds (read-across principle)
Referenceopen allclose all
Optical density compared to the control (=100%)
Conc [mg/L] | Optical density | % of control |
0 | 100 | |
7.81 | 0.394 | 100.51 |
15.63 | 0.396 | 100.89 |
31.25 | 0.352 | 89.67 |
62.5 | 0.156 | 39.83 |
125 | 0.017 | 4.4 |
250 | 0.002 | 0.38 |
500 | 0.003 | 0.64 |
1000 | 0.002 | 0.51 |
Optical density compared to the control (=100%)
Conc [mg/L] | Optical density | % of control |
0 | 100 | |
7.81 | 0.443 | 98.06 |
15.63 | 0.482 | 106.7 |
31.25 | 0.496 | 109.74 |
62.5 | 0.51 | 112.84 |
125 | 0.438 | 96.85 |
250 | 0.301 | 66.52 |
500 | 0.184 | 40.79 |
1000 | 0.122 | 27.06 |
Optical density compared to the control (=100%)
Conc [mg/L] | Optical density | % of control |
0 | 100 | |
7.81 | 0.409 | 99.51 |
15.63 | 0.404 | 98.42 |
31.25 | 0.374 | 91.11 |
62.5 | 0.212 | 51.55 |
125 | 0.038 | 9.19 |
250 | 0.002 | 0.49 |
500 | 0.002 | 0.43 |
1000 | 0.001 | 0.24 |
Concentration (mg/L | Oxygen consumption (mg/L per hour) | Inhibition (%) |
0 | 68.28 | 2.03 |
10 | 68.40 | 1.85 |
32 | 71.10 | -2.03 |
100 | 70.07 | -0.55 |
316 | 72.85 | -4.54 |
1000 | 71.27 | -2.26 |
0 | 71.10 | -2.03 |
Concentration (mg/L) | Oxygen consumption (mg/L per hour) | Inhibition (%) |
0 | 82.88 | 0.46 |
10 | 84.21 | -1.14 |
32 | 111.5 | -33.91 |
100 | 104.95 | -26.04 |
316 | 90.46 | -8.64 |
1000 | 86.00 | -3.28 |
0 | 83.65 | -0.46 |
Description of key information
In activated sludge respiration inhibition tests, effects of sodium sulfite and ammonium thiosulfate were not observed at the limit concentration of 1000 mg test item/L. Furthermore, potassium as essential element has a very low potential for toxicity to aquatic microorganisms. Based on read-across to thiosulfate/sulfite/disulfite substances and soluble potassium substances and taking into account ubiquitousness and essentiality of potassium and sulfur, the potential of potassium thiosulfate for toxicity to STP microorganisms can be expected to be very low.
Key value for chemical safety assessment
Additional information
Studies on the toxicity of potassium thiosulfate to aquatic microorganisms are not available, and thus, read-across to thiosulfate and sulfite/disulfite substances is applied. Upon contact with water, salts of sulfur oxyacids including potassium thiosulfate dissociate into sulfur oxyacid anions and the respective counterions. Only the properties of the thiosulfate anion are considered a relevant determinant of environmental toxicity since potassium cations are essential and have a very low potential for toxicity to aquatic microorganisms. Please refer to the respective endpoint summary for potassium (K) for further details.Thiosulfate anions are unstable under environmentally relevant conditions, will disproportionate to sulfite and will further be oxidized to sulfate or reduced to sulfide.
Sulfite/disulfite and thiosulfate substances – Toxicity to microorganisms
A reliable OECD No. 209 respiration inhibition test (under GLP) was performed with sodium sulfite (Na2SO3). The activated sludge originates from a sewage treatment plant in Frankfurt/Main Niederrad treating predominantly domestic sewage. Effects on respiration were not observed at the highest test concentration of 1000 mg test substance/L, and the 3h-NOEC expressed as sulfite (SO32-) amounts to ≥ 634.4 mg/L.
Furthermore, an OECD No. 209 respiration inhibition test (under GLP) was performed with ammonium thiosulfate. Significant adverse effects were not observed up to the highest test concentration of 1000 mg/L after 3 h, resulting in a NOEC value ≥ 1000 mg/L (corresponding to ≥ 540.2 mg SO32-/L).
The absence of any toxicity at this level is confirmed by a 16h-EC50 of 2000 mg NaSO3/L (corresponding to 1268 mg SO32-) determined in a growth inhibition test on a mixed culture of bacteria by Alsop et al. (1980).
Additionally, the growth inhibition of the bacterium Pseudomonas putida by three different sulfite substances (i.e., potassium sulfite (K2SO3), disodium disulfite (Na2S2O5) and potassium metabisulfite (K2S2O5)) was tested and the following effect levels were determined:
Substance |
MM |
% S |
17 h-EC50(mg test item/L) |
17 h-EC50(mg S/L) |
17 h-EC50(mg SO32-/L) |
Reference |
K2SO3 |
158.26 |
20.3 |
410 |
83.1 |
207.2 |
BASF, 1988a |
K2S2O5 |
222.32 |
28.8 |
65 |
18.8 |
46.8 |
BASF, 1988b |
Na2S2O5 |
190.1 |
33.7 |
56.1 |
18.9 |
47.2 |
BASF, 1988c |
|
|
|
17 h-EC10(mg test item/L) |
17 h-EC10(mg S/L) |
17 h-EC10(mg SO32-/L) |
|
K2SO3 |
158.26 |
20.3 |
153 |
31 |
77.3 |
BASF, 1988a |
K2S2O5 |
222.32 |
28.8 |
32 |
9.2 |
23.0 |
BASF, 1988b |
Na2S2O5 |
190.1 |
33.7 |
30.8 |
10.4 |
25.9 |
BASF, 1988c |
ECHA Guidance on IR & CSA, Chapter 7b: Endpoint Specific Guidance (Version 4.0, 2017) states that “Results of the cell multiplication inhibition test with P. putida (Bringmann and Kühn 1980) should be used for calculation of the PNECmicro-organisms only in cases where no other test results are available.” Thus, results are considered as supporting only and the hazard assessment is based on results from activated sludge respiration inhibition tests.
In activated sludge respiration inhibition tests, effects of sodium sulfite and ammonium thiosulfate were not observed at the highest test concentration of 1000 mg test item/L, the OECD test limit, respectively. Thus, the potential of thiosulfate and sulfite/disulfite substances for toxicity to STP microorganisms can be expected to be very low.
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