Registration Dossier
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EC number: 231-890-0 | CAS number: 7775-14-6
- 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
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- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
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- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
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- Nanomaterial pour density
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- Endpoint summary
- Stability
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- 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
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- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
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- Repeated dose toxicity
- Genetic toxicity
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- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data

Basic toxicokinetics
Administrative data
- Endpoint:
- basic toxicokinetics in vitro / ex vivo
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Study period:
- no data available
- Justification for type of information:
- Read-across
The basis for the read-across concept for this project is the equilibrium between sulfites, hydrogensulfites, and metabisulfites in aqueous solutions depending on pH value which is clearly described in published literature and summarised in the following equations:[1],[2]
SO2 + H2O <->`H2SO3´ H2SO3<->H+ + HSO3- <-> 2H+ +SO32- 2HSO3- <->H2O +S2O52 –
As the nature of the cation should make no significant difference in this case concerning toxicity and solubility (all compounds are very soluble in water), only the chemical and biological properties of the anion are considered relevant. Based on the described equilibrium correlations, we propose unrestricted read-across between the groups of sulfites, hydrogensulfites and metabisulfites. Additionally, it is known that sodium dithionite disproportionates in water to form sodium hydrogen sulfite and sodium thiosulfate (equation II) so that this substance can also be added to the read-across concept.[2],[1]
It is expected for this case that the substance is not stable enough under physiological conditions to fulfil the requirements of study guidelines and so the products of decomposition have to be considered.
2 S2O42-+ H2O→2HSO3-+ S2O32 -
All sulfite, hydrogensulfite and metabisulfite substances are highly soluble in water, establishing upon dissolution an equilibrium that depends on solution pH as follows: ,
1. SO2 + H2O <-> H2SO3
2. H2SO3 <-> H+ + HSO3- <-> 2H+ + SO32-
3. 2 HSO3- <-> H2O + S2O52-
Under oxidising conditions, e.g., in surface waters, sulfite is oxidized to sulfate catalytically by (air) oxygen or by microbial action. A half-life of 77 hour was measured in deionized water, already suggesting substantial abiotic degradation. However, the presence of metal cations in the environment, such as copper, iron and manganese, accelerates the oxidation rate. In soils, HSO3- and SO32- ions are unstable and quickly oxidise. Further, because of the instability of SO32-, metal sulfites are generally too soluble to persist in soils. Thus, the most stable and predominant sulfur form in freshwater and in all but highly reduced environments is sulfate (SO42-). In highly reduced soils and sediments, sulfites may be reduced to sulfides (Lindsay, 1979; OECD SIDS, 2012).
Only the properties of the sulfite anion are considered relevant determinants of environmental toxicity since respective cations, i.e. ammonium, calcium, magnesium, sodium and potassium, are not assumed to contribute substantially to differences therein. Sulfite, although naturally present in the environment and also a metabolite and intermediate of sulfur-containing amino acids in organisms, may have an impact on the environment at elevated levels. Sulfites do not bioaccumulate.
In sum, unrestricted read-across between the sulfites, hydrogensulfites and metabisulfites is justified.
Cross-referenceopen allclose all
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- basic toxicokinetics in vitro / ex vivo
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Study period:
- no data available
- Justification for type of information:
- Read-across
The basis for the read-across concept for this project is the equilibrium between sulfites, hydrogensulfites, and metabisulfites in aqueous solutions depending on pH value which is clearly described in published literature and summarised in the following equations:[1],[2]
SO2 + H2O <->`H2SO3´ H2SO3<->H+ + HSO3- <-> 2H+ +SO32- 2HSO3- <->H2O +S2O52 –
As the nature of the cation should make no significant difference in this case concerning toxicity and solubility (all compounds are very soluble in water), only the chemical and biological properties of the anion are considered relevant. Based on the described equilibrium correlations, we propose unrestricted read-across between the groups of sulfites, hydrogensulfites and metabisulfites. Additionally, it is known that sodium dithionite disproportionates in water to form sodium hydrogen sulfite and sodium thiosulfate (equation II) so that this substance can also be added to the read-across concept.[2],[1]
It is expected for this case that the substance is not stable enough under physiological conditions to fulfil the requirements of study guidelines and so the products of decomposition have to be considered.
2 S2O42-+ H2O→2HSO3-+ S2O32 -
All sulfite, hydrogensulfite and metabisulfite substances are highly soluble in water, establishing upon dissolution an equilibrium that depends on solution pH as follows: ,
1. SO2 + H2O <-> H2SO3
2. H2SO3 <-> H+ + HSO3- <-> 2H+ + SO32-
3. 2 HSO3- <-> H2O + S2O52-
Under oxidising conditions, e.g., in surface waters, sulfite is oxidized to sulfate catalytically by (air) oxygen or by microbial action. A half-life of 77 hour was measured in deionized water, already suggesting substantial abiotic degradation. However, the presence of metal cations in the environment, such as copper, iron and manganese, accelerates the oxidation rate. In soils, HSO3- and SO32- ions are unstable and quickly oxidise. Further, because of the instability of SO32-, metal sulfites are generally too soluble to persist in soils. Thus, the most stable and predominant sulfur form in freshwater and in all but highly reduced environments is sulfate (SO42-). In highly reduced soils and sediments, sulfites may be reduced to sulfides (Lindsay, 1979; OECD SIDS, 2012).
Only the properties of the sulfite anion are considered relevant determinants of environmental toxicity since respective cations, i.e. ammonium, calcium, magnesium, sodium and potassium, are not assumed to contribute substantially to differences therein. Sulfite, although naturally present in the environment and also a metabolite and intermediate of sulfur-containing amino acids in organisms, may have an impact on the environment at elevated levels. Sulfites do not bioaccumulate.
In sum, unrestricted read-across between the sulfites, hydrogensulfites and metabisulfites is justified. - Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Objective of study:
- other: disappearance from serum or plasma
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The hydrate of sulfur dioxide in mammalian plasma and serum was investigated. The longevity of sulfite in contact with mammalian plasma and known components of blood was investigated. The reactivity of sulfite added to serum or plasma in vitro was followed by monitoring the concentration of the sulfite in the reaction mixture.
- GLP compliance:
- no
- Radiolabelling:
- no
- Species:
- rabbit
- Strain:
- New Zealand White
- Sex:
- not specified
- Details on test animals or test system and environmental conditions:
- No details are given.
- Route of administration:
- other: not applicable
- Vehicle:
- water
- Details on exposure:
- Plasma and serum samples were collected from the marginal ear vein of adult rabbits with the aid of a suction device.
Edetate disodium at 2 mg/mL was used as an anticoagulant in the plasma samples. - Duration and frequency of treatment / exposure:
- continuously until measurement (after 20 minutes)
- Dose / conc.:
- 1.7 other: nanomols of sulfite
- Dose / conc.:
- 3.6 other: nanomols of sulfite
- Dose / conc.:
- 5.2 other: nanomols of sulfite
- No. of animals per sex per dose / concentration:
- not applicable
- Control animals:
- no
- Positive control reference chemical:
- No positive control substance was tested
- Details on study design:
- no data
- Details on dosing and sampling:
- Analysis of sulfite in presence of plasma or serum: To 200 µL of solution containing 40 µL of serum or plasma, approximately 6 microequivalents of hydrochloric acid, and quantities (up to 5.2 nM) of sulfite, 20 µL of PRA and 20 µL of formaldehyde reagent were added. A serum or plasma reagent blank was prepared. The optical density was measured against this blank after 20 minutes at 560 mµ.
in vitro reaction of sulfite with plasma or serum: Serum or plasma was incubated with a known amount of sulfite in a nitrogen atmosphere at 37°C, pH 7.4, using a ratio of 1 volume of serum (or plasma) to 1 volume of buffer and sulfite. These conditions are referred to as standard pH 7.4 incubation conditions. After incubation for the desired period of time, the amount of sulfite remaining in the mixture was analysed according the the procedure described above. This determination indirectly gives the amount of sulfite that "disappeared" from the incubation mixture and which was assumed to have reacted with the serum (or plasma).
Each analysis was replicated six times. - Statistics:
- no data
- Preliminary studies:
- no data
- Type:
- other: disappearance from serum or plasma
- Results:
- Sulfite which enters the bloodstream during exposure of a mammal to atmospheric SO2 forms S-sulfonate groups with constituents of the plasma, probably exclusively by sulfitolysis of disulfide groups.
- Details on absorption:
- no data
- Details on distribution in tissues:
- no data
- Details on excretion:
- no data
- Metabolites identified:
- no
- Details on metabolites:
- No details are given.
- Conclusions:
- The results give evidence that sulfite which enters the bloodstream during exposure of a mammal to atmospheric SO2 forms S-sulfonate groups with constituents of the plasma, probably exclusively by sulfitolysis of disulfide groups.
This interaction probably affords protection to many tissues of the body from the insult of high concentrations of sulfite.
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- basic toxicokinetics in vivo
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Study period:
- no data available
- Justification for type of information:
- Read-across
The basis for the read-across concept for this project is the equilibrium between sulfites, hydrogensulfites, and metabisulfites in aqueous solutions depending on pH value which is clearly described in published literature and summarised in the following equations:[1],[2]
SO2 + H2O <->`H2SO3´ H2SO3<->H+ + HSO3- <-> 2H+ +SO32- 2HSO3- <->H2O +S2O52 –
As the nature of the cation should make no significant difference in this case concerning toxicity and solubility (all compounds are very soluble in water), only the chemical and biological properties of the anion are considered relevant. Based on the described equilibrium correlations, we propose unrestricted read-across between the groups of sulfites, hydrogensulfites and metabisulfites. Additionally, it is known that sodium dithionite disproportionates in water to form sodium hydrogen sulfite and sodium thiosulfate (equation II) so that this substance can also be added to the read-across concept.[2],[1]
It is expected for this case that the substance is not stable enough under physiological conditions to fulfil the requirements of study guidelines and so the products of decomposition have to be considered.
2 S2O42-+ H2O→2HSO3-+ S2O32 -
All sulfite, hydrogensulfite and metabisulfite substances are highly soluble in water, establishing upon dissolution an equilibrium that depends on solution pH as follows: ,
1. SO2 + H2O <-> H2SO3
2. H2SO3 <-> H+ + HSO3- <-> 2H+ + SO32-
3. 2 HSO3- <-> H2O + S2O52-
Under oxidising conditions, e.g., in surface waters, sulfite is oxidized to sulfate catalytically by (air) oxygen or by microbial action. A half-life of 77 hour was measured in deionized water, already suggesting substantial abiotic degradation. However, the presence of metal cations in the environment, such as copper, iron and manganese, accelerates the oxidation rate. In soils, HSO3- and SO32- ions are unstable and quickly oxidise. Further, because of the instability of SO32-, metal sulfites are generally too soluble to persist in soils. Thus, the most stable and predominant sulfur form in freshwater and in all but highly reduced environments is sulfate (SO42-). In highly reduced soils and sediments, sulfites may be reduced to sulfides (Lindsay, 1979; OECD SIDS, 2012).
Only the properties of the sulfite anion are considered relevant determinants of environmental toxicity since respective cations, i.e. ammonium, calcium, magnesium, sodium and potassium, are not assumed to contribute substantially to differences therein. Sulfite, although naturally present in the environment and also a metabolite and intermediate of sulfur-containing amino acids in organisms, may have an impact on the environment at elevated levels. Sulfites do not bioaccumulate.
In sum, unrestricted read-across between the sulfites, hydrogensulfites and metabisulfites is justified. - Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Objective of study:
- other: disappearance from plasma
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The hydrate of sulfur dioxide in mammalian plasma was investigated. The longevity of sulfite in contact with mammalian plasma and known components of blood was investigated.
Rabbits were exposed to SO2 by inhalation for 14 or 62 hours and any free sulfite present in the plasma was determined as cyanolytic sulfite. - GLP compliance:
- no
- Radiolabelling:
- no
- Species:
- rabbit
- Strain:
- New Zealand White
- Sex:
- not specified
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Age at study initiation: 4 to 22 months
- Weight at study initiation: 3 to 4 kg
- Diet: ad libitum
- Water: ad libitum
No more details are given. - Route of administration:
- inhalation
- Vehicle:
- other: air
- Details on exposure:
- TYPE OF INHALATION EXPOSURE: whole body
GENERATION OF TEST ATMOSPHERE / CHAMPER DESCRIPTION
A plasic glove box with approximately 8 cu ft of space was used as an SO2 exposure chamber for rabbits. Sulfur dioxide was metered into a 12-inch polyethylene tube where it was mixed with ambient air. The mixture was pulled through the chamber at a rate of 2.4 cu ft/minute (1 air change every 3.4 minutes) by a rotary, vane type pump. The concentration of SO2 in the chamber was determined by the West and Gaeke method. The distribution of pollutant within the chamber proved satisfactory, however, there was considerable fluctuations in So2 concentration over an extended period of time due to imperfect regulation of SO2 input. The average SO2 concentration was 23.5 +/- 5 ppm.
One rabbit was exposed at a time.
TEST ATMOSPHERE (if not tabulated)
na data - Duration and frequency of treatment / exposure:
- Rabbits 1 and 2: 14 hours + >200 hours post exposure
Rabbits 3 and 4: 62 hours + >200 hours post exposure - Dose / conc.:
- 23.5 ppm
- No. of animals per sex per dose / concentration:
- 4 rabbits
- Control animals:
- yes
- Positive control reference chemical:
- No positive control substance was tested.
- Details on study design:
- no data
- Details on dosing and sampling:
- Two or three 1-mL aliquots from each plasma and serum sample were incubated according standard alkaline cyanide conditions. Liberated sulfite was recovered by repeated dialysis for 2.75 hours.
In this analytical procedure, any free sulfite present in the plasma would be determined as cyanolytic sulfite. - Statistics:
- no data
- Preliminary studies:
- no data
- Results:
- A sharp increase in cyanolytic sulfite was detected immediately after SO2 exposure in all four rabbits.
- Type:
- other: disappearance from plasma
- Results:
- Sulfite which enters the bloodstream during exposure of a mammal to atmospheric SO2 forms S-sulfonate groups with constituents of the plasma, probably exclusively by sulfitolysis of disulfide groups.
- Details on absorption:
- no data
- Details on distribution in tissues:
- no data
- Details on excretion:
- no data
- Metabolites identified:
- no
- Conclusions:
- The results give evidence that sulfite which enters the bloodstream during exposure of a mammal to atmospheric SO2 forms S-sulfonate groups with constituents of the plasma, probably exclusively by sulfitolysis of disulfide groups.
This interaction probably affords protection to many tissues of the body from the insult of high concentrations of sulfite.
Data source
Reference
- Reference Type:
- publication
- Title:
- Sulfur dioxide: Sulfite
- Author:
- Gunnison, A. F. & Benton, A.W.
- Year:
- 1 971
- Bibliographic source:
- Arch. Environ. Health, Vol. 22: 381 - 388.
Materials and methods
- Objective of study:
- other: disappearance from serum or plasma
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The hydrate of sulfur dioxide in mammalian plasma and serum was investigated. The longevity of sulfite in contact with mammalian plasma and known components of blood was investigated.
The reactivity of sulfite added to serum or plasma in vitro was followed by monitoring the concentration of the sulfite in the reaction mixture. - GLP compliance:
- no
Test material
- Reference substance name:
- sulfite
- IUPAC Name:
- sulfite
- Details on test material:
- - Name of test material (as cited in study report): Sulfite
- Analytical purity: reagent grade
Constituent 1
- Radiolabelling:
- no
Test animals
- Species:
- human
- Sex:
- not specified
- Details on test animals or test system and environmental conditions:
- not applicable
Administration / exposure
- Route of administration:
- other: not applicable
- Vehicle:
- water
- Details on exposure:
- Plasma and serum samples were collected from an arm vein of adult humans with evacuated test tubes.
Edetate disodium at 2 mg/mL was used as an anticoagulant in the plasma samples. - Duration and frequency of treatment / exposure:
- continuously until measurement (after 20 minutes)
Doses / concentrationsopen allclose all
- Dose / conc.:
- 1.7 other: nanomols of sulfite
- Dose / conc.:
- 3.6 other: nanomols of sulfite
- Dose / conc.:
- 5.2 other: nanomols of sulfite
- No. of animals per sex per dose / concentration:
- not applicable
- Control animals:
- no
- Positive control reference chemical:
- No positive control substance was tested
- Details on study design:
- no data
- Details on dosing and sampling:
- Analysis of sulfite in presence of plasma or serum: To 200 µL of solution containing 40 µL of serum or plasma, approximately 6 microequivalents of hydrochloric acid, and quantities (up to 5.2 nM) of sulfite, 20 µL of PRA and 20 µL of formaldehyde reagent were added. A serum or plasma reagent blank was prepared. The optical density was measured against this blank after 20 minutes at 560 mµ.
in vitro reaction of sulfite with plasma or serum: Serum or plasma was incubated with a known amount of sulfite in a nitrogen atmosphere at 37°C, pH 7.4, using a ratio of 1 volume of serum (or plasma) to 1 volume of buffer and sulfite. These conditions are referred to as standard pH 7.4 incubation conditions. After incubation for the desired period of time, the amount of sulfite remaining in the mixture was analysed according the the procedure described above. This determination indirectly gives the amount of sulfite that "disappeared" from the incubation mixture and which was assumed to have reacted with the serum (or plasma).
Each analysis was replicated six times. - Statistics:
- no data
Results and discussion
- Preliminary studies:
- no data
Main ADME results
- Type:
- other: disappearance from serum or plasma
- Results:
- Sulfite which enters the bloodstream during exposure of a mammal to atmospheric SO2 forms S-sulfonate groups with constituents of the plasma, probably exclusively by sulfitolysis of disulfide groups.
Toxicokinetic / pharmacokinetic studies
- Details on absorption:
- no data
- Details on distribution in tissues:
- no data
- Details on excretion:
- no data
Metabolite characterisation studies
- Metabolites identified:
- no
- Details on metabolites:
- No details are given.
Applicant's summary and conclusion
- Conclusions:
- The results give evidence that sulfite which enters the bloodstream during exposure of a mammal to atmospheric SO2 forms S-sulfonate groups with constituents of the plasma, probably exclusively by sulfitolysis of disulfide groups.
This interaction probably affords protection to many tissues of the body from the insult of high concentrations of sulfite.
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