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EC number: 231-982-0 | CAS number: 7783-18-8
- 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
Endpoint summary
Administrative data
Description of key information
Studies on the aquatic toxicity of ammonium thiosulfate are available for fish (acute: Lepomis macrochirus, Oncorhynchus mykiss), crustaceans (acute: Daphnia magna, Mysidopsis bahia), algae (Pseudokirchneriella subcapitata) and STP microorganisms.
In addition, read-across to thiosulfate and sulfite/disulfite substances and ammonium cations is applied.Upon contact with water, salts of sulfur oxyacids including ammonium thiosulfate dissociate into sulfur oxyacid anions and the respective counterions.
Ammonium is a natural component of the environment and found in soil, air, and water.Ammonium is essential for many biological processes, serves as a precursor for amino acid and nucleotide synthesis and provides e.g. a source of nitrogen for plants. Ammonium is produced by bacteria in water and soil from decomposition of organic matter, including plants, animals and animal wastes. Ammonium goes through biochemical transformations in soil and water as part of the nitrogen cycle, is rapidly degraded, i.e. mineralized by numerous species of bacteria, and therefore not expected to accumulate in the environment. Based on the available data, its aquatic toxicity is considered to be low.Please refer to the respective endpoint summary for ammonium (NH4) 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 (please refer to the endpoint summary on environmental fate and behaviour).Acute and chronic toxicity studies with thiosulfate and sulfite/disulfite substances are available for three trophic levels. In studies with controlled oxygen concentrations and pH, acute toxicity for all three trophic levels (freshwater fish and algae and freshwater and marine invertebrates) is only observed at concentrations above the respective OECD test limit of 100 mg/L.
In chronic studies with controlled oxygen concentrations and pH, effect values are unbounded (D. rerio, D. magna, P. subcapitata) or above the chronic OECD test limit of 10 mg/L (D. subspicatus, C. vulgaris, C. reinhardtii).
Effects of thiosulfate and sulfite substances on the respiration of activated sludge were not observed at the OECD test limit of 1000 mg/L, respectively.
It is thus concluded that thiosulfate and sulfite/disulfite substances, including ammonium thiosulfate, are not toxic to freshwater fish, invertebrates, algae and microorganisms.
Additional information
Thiosulfate and sulfite/disulfite substances -Summary of acute toxicity data
Reliable acute toxicity data are available for several aquatic freshwater species covering three trophic levels (primary producers, primary and secondary consumers) and one saltwater species (invertebrates). The table below provides an overview of the effect values for the acute toxicity of thiosulfate and sulfite/disulfite substances applied in a weight of evidence approach.
Table: Overview of reliable acute toxicity data for thiosulfate and sulfite/disulfite substances
Species |
Parameter |
Endpoint |
EC [mg SO32-/L] |
Observed interference |
Test substance |
Reference |
Lepomis macrochirus |
mortality |
96 h LC50 |
275.5 |
oxygen depletion** |
ammonium thiosulfate |
Springborn Binomics Inc, 1986 |
Oncorhynchus mykiss |
mortality |
96 h LC50 |
416 |
oxygen depletion** |
ammonium thiosulfate |
Springborn Binomics Inc, 1986 |
Oncorhynchus mykiss |
mortality |
96 h LC50 |
149.6 |
pH decrease* |
disodium disulfite |
BASF, 1981 |
Leuciscus idus |
mortality |
96 h LC50 |
200.5 |
oxygen depletion** |
sodium sulfite |
BASF, 1989 |
Leuciscus idus |
mortality |
96 h LC50 |
159.7 |
oxygen depletion** |
potassium sulfite |
BASF, 1989 |
Danio rerio |
mortality |
96 h LC50 |
490 |
oxygen depletion** |
dipotassium disulfite |
BASF, 1995 |
Daphnia magna |
mobility |
48 h EC50 |
124.2 |
none |
ammonium thiosulfate |
Springborn Binomics Inc, 1986 |
Mysidopsis bahia |
mortality |
96 h LC50 |
41.6 |
oxygen depletion** |
ammonium thiosulfate |
Springborn Binomics Inc, 1994 |
Daphnia magna |
mobility |
48 h EC50 |
74.9 |
oxygen depletion** |
disodium disulfite |
BASF, 1990 |
Pseudokirchneriella subcapitata |
growth rate |
72 h EC50 |
>54 |
none |
ammonium thiosulfate |
ECT, 2010 |
Desmodesmus subspicatus |
growth rate |
72 h EC50 |
36.8 |
pH decrease* |
disodium disulfite |
BASF, 1989 |
*pH decrease: solution pH at “toxic” test concentrations is outside OECD test criteria
**oxygen depletion: oxygen concentration of medium at “toxic” test concentrations is outside OECD test criteria
In tests with ammonium thiosulfate and without experimental interferences (e.g., oxygen depletion in the test medium), the effect concentration was either above the OECD test limit of 100 mg/L (test with ammonium thiosulfate and D. magna; 48h EC50 =124.4 mg/L), or above the highest tested concentration of 100 mg ammonium thiosulfate/L (corresponding to 54 mg SO32-/L; test with ammonium thiosulfate and P. subcapitata; 72 h EC50).
Other acute effect concentrations (EC/LC50s) are i) unbounded, ii) above the test limit of 100 mg/L as defined in the respective OECD guideline (OECD 201, 202, 203), and/or iii) presumably caused by to oxygen depletion and/or a pH decrease and do not represent the intrinsic toxicity of sulfite/disulfite and thiosulfate substances. Thus, it may be assumed that the “substance-specific” EC/LC50 of thiosulfate substances for freshwater fish and algae and freshwater and marine invertebrates is higher than the EC50/LC50s derived in studies applying a test system without proper buffering capacity for oxygen concentrations and pH.
It is thus concluded that thiosulfate and sulfite/disulfite substances, including ammonium thiosulfate, are not acutely toxic to freshwater fish and algae and freshwater and marine invertebrates. Additionalstudies on the acute effects of disodium disulfite toDaphnia magna and Raphidocelis subcapitata according to OECD 202 and OECD 201, respectively, with appropriate aeration and buffering of thetest system, are currently ongoing.
Thiosulfate and sulfite/disulfite substances -Summary of chronic toxicity data
Chronic toxicity data are available for several aquatic freshwater species covering three trophic levels (primary producers, primary and secondary consumers). The table below provides an overview of the effect values for chronic toxicity of sulfite/disulfite and thiosulfate substances.
Table: Overview of reliable chronic toxicity data for thiosulfate and sulfite/disulfite substances
Species |
Parameter |
Endpoint |
EC [mg SO32-/L] |
Observed interference |
Test substance |
Reference |
Danio rerio |
all (ELS) |
34 d NOEC |
≥ 200.5 |
none |
sodium sulfite |
ECT, 2010 |
Daphnia magna |
reproduction, mortality |
21 d NOEC |
≥ 8.41 |
none |
disodium disulfite |
BASF, 1993 |
Pseudokirchneriella subcapitata |
growth rate |
72 h NOEC |
≥ 54 |
none |
ammonium thiosulfate |
ECT, 2010 |
Desmodesmus subspicatus |
growth rate |
72 h EC10 |
28 |
pH decrease* |
disodium disulfite |
BASF, 1989 |
*pH decrease: solution pH decreases at higher test concentrations
**oxygen depletion: oxygen concentration of medium at “toxic” test concentrations is outside OECD test criteria
Chronic effect values of ammonium thiosulfate are unbounded, without effects at the highest test concentration (P. subcapitata). Other chronic effect values are i) unbounded, without effects at the highest test concentration (D. rerio, D. magna) or ii) above the chronic OECD test limit of 10 mg/L (D. subspicatus).
It is thus concluded that thiosulfate or sulfite/disulfite substances, including ammonium thiosulfate, are not chronically toxic to freshwater fish, invertebrates and algae.
Toxicity to STP microorganisms
Regarding the toxicity to microorganisms, reliable studies of the respiration inhibition of activated sludge and supporting studies of the growth inhibition of Pseudomonas putida are available (see Table below).
Table: Overview of reliable toxicity data to microorganisms for thiosulfate and sulfite/disulfite substances
Species |
Parameter |
Endpoint |
EC [mg SO32-/L] |
Test substance |
Reference |
Activated sludge |
respiration inhibition |
3 h EC50 3 h NOEC |
> 540.2 ≥ 540.2 |
ammonium thiosulfate |
ECT, 2010 |
Activated sludge |
respiration inhibition |
3 h EC50 3 h NOEC |
> 634.4 ≥ 634.4 |
sodium sulfite |
ECT, 2010 |
Pseudomonas putida |
growth inhibition |
17 h EC50 17 h EC10 |
47.2 25.9 |
disodium disulfite |
BASF, 1988a |
Pseudomonas putida |
growth inhibition |
17 h EC50 17 h EC10 |
207.2 77.3 |
potassium sulfite |
BASF, 1988b |
Pseudomonas putida |
growth inhibition |
17 h EC50 17 h EC10 |
65.8 23 |
potassium disulfite |
BASF, 1988c |
Effects on the respiration of activated sludge were not observed at the OECD test limit of 1000 mg/L in studies with ammonium thiosulfate or sodium sulfite, respectively.
The hazard assessment is based on effect concentrations for the respiration inhibition of activated sludge in accordance with ECHA guidance on IR & CSA, Chapter 7b (Version 4.0, 2017).
It is thus concluded that thiosulfate and sulfite/disulfite substances, including ammonium thiosulfate, are not toxic to aquatic microorganisms.
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