Sodium dithionite

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions, no analytical dose verification, pH did not remain in the acceptable range for all 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:

other: German Industrial Standard Guideline Number DIN 38 412 Group L, part 1 and part 15

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Strain: Salmo gairdneri
- Source: Forellenhof Fredelsloh, Germany
- Length at study initiation: 7.6 cm
- Weight at study initiation: 5.4 g
- Feeding during test: no
- Frequency: Withdrawal of food before exposure: 1 day


ACCLIMATION
- Acclimation conditions (same as test or not): yes
- Water temperature: 16±1.5 °C
- Acclimation to test water and test temperature: 3 days

HOUSING
- Housing water: charcoal filtered dechlorinated water in continuous flow-through
- Aeration: oilfree air
- Light regime: 16 : 8 hours light : dark
- Hardness: 1.3-2.6 mM
- Oxygen concentration: > 6 mg/L
- pH: 7.0-8.0
- Water temperature: 16±1.5 °C
- Medical treatment: none
- Feeding: Fukosalm Anschlussfutter 1, FUKO, Ulm, Germany
- Amount of feed: ad libitum

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

2.6 mmol/L

Test temperature:

16 ± 1.5°C

pH:

test start: 5.0-7.6
test end: 4.3-7.4

Dissolved oxygen:

test start: 2.8-8.8 mg/L
test end: 8.4-9.2 mg/L

Nominal and measured concentrations:

0, 68.1, 100, 147, 215 and 316 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): aquaria open
- Material, size, fill volume: glass, 30 x 22 x 24 cm, 10 L
- Aeration: aeration with oil-free air
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted freshwater was prepared from demineralized tap water that was resalted by the addition of 344 mg/l CaSO4.2H2O, 124 mg/l MgSO4.7H2O, 70 mg/l NaHCO3 and 3 mg/l KCl.
- Ca/Mg ratio: 8 : 1
- Intervals of water quality measurement: 1, 24, 48, 72, and 96 hours

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality and symptoms after 1, 24, 48, 72, and 96 hours

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

147 - 215 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

177.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: geometric mean of 147 and 215 mg/L

Sublethal observations / clinical signs:

Mortality after 96 h was 0/10 in the 0, 68.1, 100 and 147 mg/l groups, 9/10 in the 215 mg/l group, and 10/10 in the 316 mg/l group. The LC50 value was calculated using probit analysis (Finney, D.J. Probit Analysis, Cambridge Univ. Press, 1971).

pH values during the test

Conc. mg/l        starting pH        ending pH

0                      7.6                    7.4

68.1                  6.5                    7.1

100                   6.1                    6.8

147                   6.0                    5.0

215                   5.6                    4.3

316                   5.0                    2.7

DO values during the test

Conc. mg/l        starting DO        ending DO

0                      8.8                    8.5

68.1                  7.7                    8.6

100                   7.1                    8.4

147                   6.1                    8.9

215                   5.9                    9.2

316                   2.8                    9.9

Symptoms:

215 mg/l - restlessness after 24 hours

215 mg/l - tumbling, side position, accelerated respiration

Validity criteria fulfilled:

not applicable

Conclusions:

A standard acute fish toxicity test was conducted with Oncorhynchus mykiss (previous name: Salmo gairdneri), using sodium pyrosulfite (Na2S2O5) as test compound. A 96 h LC50 of 177.8 mg test item/L was derived as the geometric mean of 147 and 215 mg test item/L, which corresponds to 149.6 mg sulfite/L (nominal). However, at concentrations ≥ 147 mg/L the pH of the test solution dropped below the acceptable range of 6.0-8.5 as specified for Oncorhynchus mykiss in OECD test guideline 203. Since the derived LC50 of 177.8 mg test item/L is within this concentration range, effects observed on the survival of O. mykiss at this level could be associated with indirect effects of solution pH. At the test concentration of 316 mg test item/L, furthermore oxygen depletion could be observed as dissolved oxygen concentrations dropped below 60% of the air saturation value.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

1982-08-16 to 1982-08-20

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure according to national standard with acceptable restrictions (eg. low initial oxygen concentration at higher 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.

Principles of method if other than guideline:

DIN 38412, Part 15 (Draft January 1979)

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The product was added to the test water in the form of an aqueous solution (1 % w/v). The test substance was completely dissolved. Subsequently the fish were placed into the aquaria. See also below: remarks on methods
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no

Test organisms (species):

Leuciscus idus

Details on test organisms:

TEST ORGANISM
- Common name: Golden orfe (Leuciscus idus)
- Source: Fischzucht Paul Eggers, 2354 Hohenweststedt, Germany
- Length at study initiation (length definition, mean, range and SD): 5.4 cm (range 5.0 - 5.8 cm)
- Weight at study initiation (mean and range, SD): 1.18 g (range 0.85 - 1.5 g)
- Feeding during test: Withdrawal of food 1 day before and during exposure

ACCLIMATION
- Acclimation period: about 6 weeks
- Health during acclimation (any mortality observed): 0 % (two weeks before beginning of test)

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

2.5 mmol/l total hardness, 0.8 mmol/l carbonate hardness

Test temperature:

20°C

pH:

see below

Dissolved oxygen:

see below

Nominal and measured concentrations:

Nominal test concentrations: 21.5, 31.6, 46.6, 68.1,100 and 147.0 mg/L. In addition, a control was tested in parallel.
A second test was run with neutralized test solutions at 147.0 and 500 mg/l.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): no data
- Material, size, headspace, fill volume: All glass aquaria (30 x 22 x 24 cm), Volume of water: 10 L
- Aeration: Slight continuous aeration with oil-free air
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted freshwater according to DIN 38412, Part II, 1982
- Alkalinity: pH about 7.8
- Ca/mg ratio: 4 : 1


OTHER TEST CONDITIONS
- Photoperiod: 16 : 8 hours day-night regime


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
observations: mortality and symptoms after 0, 1, 4, 24, 48, 72 and 96 h
measurements: pH and oxygen content after 0, 24, 48, 72 and 96 h


TEST CONCENTRATIONS
Nominal test concentrations: 21.5, 31.6, 46.6, 68.1,100 and 147.0 mg/L. In addition, a control was tested in parallel.
A second test was run with neutralized test solutions at 147.0 and 500 mg/l.

Reference substance (positive control):

yes

Remarks:

chloracetamide

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

62.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: >46.4 - <68 mg/L

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

46.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: - gasping (after 1 h)

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Mortality: yes
- LC50: 38 mg/l

Sublethal observations / clinical signs:

- No observed effect concentration (NOEC): <21.5 mg/L
- Minimum concentration causing 100 % mortality: 100.0 mg/L

- Total number of living fish at the beginning and after 1 h
and 96 h:
concentration (mg/L) No. of living fish
(0 h) (1 h) (96 h)
21.5 10 10 10
31.6 10 10 10
46.4 10 10 10
68.1 10 2 2
100.0 10 0 0
147.0 10 0 0
control 10 10 10
147.0 (*) 10 0 0
500.0 (*) 10 0 0
(*) after pH-adjustment

- In the parallel test with neutralized concentrations of
147.0 mg/L and 500.0 mg/L all fish died within 1 hour due to
oxygen deficiency

- In a pre-test in which the fish were placed into the
aquaria 1 h after preparation of the test solution the
initial oxygen consumption was compensated by the continuous
aeration and the the conc. of 100 mg/L did not cause any
mortalities or symptoms

Conclusions:

A standard acute fish toxicity test was conducted with L. idus, using sodium dithionite as test compound. An LC50 of 62.3 mg test item/L was derive and this data point can be used for hazard/effects asessment purposes for sodium dithionite and other dithionite compounds (read-across principles)

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

1989-03-13 to 1989-03-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions; no analytical dose verification; oxygen depletion of test medium at higher 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:

other: German industrial standard test guideline DIN 38 412, part L15.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: the product was added to the test water without any pretreatment; subsequently the fish were placed into the aquaria
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no

Test organisms (species):

Leuciscus idus

Details on test organisms:

TEST ORGANISM
- Common name: Goldorfe
- Strain: Leuciscus idus (golden variety)
- Source: Fischzucht Paul Eggers, 2354 Hohenwestedt, Germany
- Length at study initiation: 6.0 cm (range: 5.5-7.1)
- Weight at study initiation: 1.8 g (range: 1.2-2.8)
- Feeding during test: no
- Frequency: Withdrawal of food before exposure: 1 day


ACCLIMATION
- Acclimation conditions (same as test or not): oil-free aerated and charcoal filtered tap water, flow-through system
Water temperature: 20-21°C
Duration of housing: about 4 weeks
Acclimation to test water and test temperature: 3 days

- Type and amount of food: Growing feed, F/B 50, SSNIEF Spezialdiaeten GmbH, Soest, Germany
- Feeding frequency: ad libitum.

HOUSING
- Housing water: charcoal filtered dechlorinated water in continuous flow-through
- Aeration: oilfree air
- Light regime: 16 : 8 hours light : dark
- Hardness: 2.5 mM
- Oxygen concentration: > 60 % of maximum saturation
- pH: about 8.0
- Water temperature: 20 - 22 °C
- Duration of housing: about 1 month
- Medical treatment: Once with 0.05 mg/L Malachitegreen and once with 10 mg/L tetracyclinhydrochlorid (CHECK!)
- Feeding: Growing feed, F/B 50, SSNIEF Spezialdiaeten GmbH, Soest, Germany
- Amount of feed: ad libitum
- Mortality during the last 2 weeks of housing: 1.4 %

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

2.5 mmol/l

Test temperature:

21°C

pH:

test start: 7.4-8.5
test end: 7.6-7.7

Dissolved oxygen:

see below

Nominal and measured concentrations:

0, 100, 215, 464, 1000 mg/L (nominal). In addition, a control was run at 1000 mg/L with oxygen adjustment after substance addition.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): aquaria open
- Material, size, fill volume: glass, 30 x 22 x 24 cm, 10 L
- Aeration: aeration with oil-free air
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 1.8 g fish /L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted freshwater according to DIN 38412, part 11
- Ca/Mg ratio: 4 : 1
- Intervals of water quality measurement: 1, 24, 48, 72, and 96 hours

OTHER TEST CONDITIONS
- Photoperiod: 16:8 hour light:dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality and symptoms after 1, 4, 24, 48, 72 and 96 hours

Reference substance (positive control):

yes

Remarks:

Chloroacetamide

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 215 - < 464 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

316 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: geometric mean of 215 and 464 mg/L

Results with reference substance (positive control):

- Results with reference substance valid? yes
- LC50 (48h): 23 mg/L

Sublethal observations / clinical signs:

LC50: >220 <460 mg/l
NOEC: 215 mg/l
LC100: 464 mg/l
LC50 calculated in Excel as geometric mean: 315.85 mg/l

Validity criteria fulfilled:

not applicable

Remarks:

dissolved oxygen below 60% of the air saturation value at test concentrations from 215 to 1000 mg/L; no control mortality

Conclusions:

A standard acute fish toxicity test was conducted with Leuciscus idus, using potassium sulfite (K2SO3) as test compound. A 96 h LC50 of 316 mg test item/L was derived, which corresponds to 159.7 mg sulfite/L (nominal). Dissolved oxygen concentrations dropped below 60% of the air saturation value (at 21 °C) at test concentrations of 215 to 1000 mg K2SO3/L. Since the derived LC50 is within this concentration range, effects observed on the survival of L.idus at this level are associated with indirect effects of oxygen depletion. If the test concentration of 1000 mg/L was aerated for 24 hours prior to test start, no mortality was observed over the 96 h test duration.

Reference 4

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

1989-03-13 to 1989-03-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions; no analytical dose verification; oxygen depletion of test medium at higher 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:

other: DIN 38412, part L15, June 1982

Principles of method if other than guideline:

The method used closely followed german industrial standard guideline DIN 38412, June 1982, using a static procedure.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: the product was added to the test water without any pretreatment; subsequently the fish were placed into the aquaria
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no

Test organisms (species):

Leuciscus idus

Details on test organisms:

TEST ORGANISM
- Common name: Golden orfe
- Strain: Leuciscus idus (golden variety)
- Source: Fischzucht Paul Eggers, 2354 Hohenwestedt, Germany
- Length at study initiation: 6.0 cm (range: 5.5-7.1)
- Weight at study initiation: 1.8 g (range: 1.2-2.8)
- Feeding during test: no
- Frequency: Withdrawal of food before exposure: 1 day


ACCLIMATION
- Acclimation conditions (same as test or not): oil-free aerated and charcoal filtered tap water, flow-through system
Water temperature: 20-21°C
Duration of housing: about 4 weeks
Acclimation to test water and test temperature: 3 days

- Type and amount of food: Growing feed, F/B 50, SSNIEF Spezialdiaeten GmbH, Soest, Germany
- Feeding frequency: ad libitum.

HOUSING
- Housing water: charcoal filtered dechlorinated water in continuous flow-through
- Aeration: oilfree air
- Light regime: 16 : 8 hours light : dark
- Hardness: 2.5 mM
- Oxygen concentration: > 60 % of maximum saturation
- pH: about 8.0
- Water temperature: 20 - 22 °C
- Duration of housing: about 1 month
- Medical treatment: Once with 0.05 mg/L Malachitegreen and once with 10 mg/L tetracyclinhydrochlorid (CHECK!)
- Feeding: Growing feed, F/B 50, SSNIEF Spezialdiaeten GmbH, Soest, Germany
- Amount of feed: ad libitum
- Mortality during the last 2 weeks of housing: 1.4 %

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

Total hardness: 2.5 mmol/L

Test temperature:

21°C

pH:

test start: 7.6-8.5
test end: 7.6-7.7

Dissolved oxygen:

see below

Nominal and measured concentrations:

Based on the results of a range finding study (LC50 after 96 h: between 100 and 1000 mg/l) the concentrations, spaced by a factor of about 2.2, were set as follows: 100, 215, 646 and 1000 mg/l.

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): aquaria open
- Material, size, fill volume: glass, 30 x 22 x 24 cm, 10 L
- Aeration: aeration with oil-free air
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 1.8 g fish /L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted freshwater according to DIN 38412, part 11
- Ca/Mg ratio: 4 : 1
- Intervals of water quality measurement: 1, 24, 48, 72, and 96 hours

OTHER TEST CONDITIONS
- Photoperiod: 16:8 hour light:dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality and symptoms after 1, 4, 24, 48, 72 and 96 hours

Reference substance (positive control):

yes

Remarks:

Chloroacetamide

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

215 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

316 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: geometric mean of 215 and 464 mg/L

Results with reference substance (positive control):

- Results with reference substance valid? yes
- LC50 (48h): 23 mg/L

Sublethal observations / clinical signs:

NOEC: 215 mg/L
LC100: 464 mg/l
LC50 was calculated as geometric mean in Excel.

Validity criteria fulfilled:

not applicable

Remarks:

dissolved oxygen below 60% of the air saturation value at test concentrations from 464 to 1000 mg/L; no control mortality

Conclusions:

A standard acute fish toxicity test was conducted with Leuciscus idus, using sodium sulfite (Na2SO3) as test compound. A 96 h LC50 of 316 mg test item/L was derived, which corresponds to 200.5 mg sulfite/L (nominal). Dissolved oxygen concentrations dropped below 60% of the air saturation value (at 21 °C) at test concentrations of 464 to 1000 mg Na2SO3/L. Since dissolved oxygen concentrations were at 60% air saturation in the 215 mg/L treatment, it can be assumed that they were below the acceptable range (<60%) at concentrations above, which includes the LC50 value of 316 mg test item/L. Effects observed on the survival of L.idus at this level are thus presumably associated with indirect effects of oxygen depletion. If the test concentration of 1000 mg/L was aerated for 24 hours prior to test start, no mortality was observed over the 96 h test duration.

Reference 5

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Study period:

1994-11-07 to 1994-11-11

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study, monitoring, GLP; oxygen depletion of test medium at higher 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:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebra fish
- Source: West Aquarium, Bad Lauterberg, Germany
- Age at study initiation (mean and range, SD): about 6 month
- Length at study initiation (length definition, mean, range and SD): 3.6 cm (3.0-4.1)
- Weight at study initiation (mean and range, SD): 0.44 g (0.29-0.66)
- Feeding during test
- Food type: Standard feed (TETRA MIN), on workdays generally additionally live artemia
- Amount: ad libitum


ACCLIMATION
- Acclimation period: 3 days
- Conditions equivalent to housing
- Health during acclimation (any mortality observed): 1 % mortality during the last 14 days prior to test initiation

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

Total hardness: about 2.5 mM (about 250 mg/L CaCO3)
Acid capacity: about 5.5 mM

Test temperature:

22 - 23 °C

pH:

test start: 6.7-8.7
test end: 8.3-8.5

Dissolved oxygen:

see below

Nominal and measured concentrations:

0, 46.6, 100, 215, 464, 1000 mg/L (nominal)
0, 46, 120, 236, 496, 1009 mg/L (measured)
Recovery rates in % after 96 hours: 99.1-120%

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: all-glass aquaria, 30 x 22 x 24 cm, 10 L fill volume
- Aeration: slight with oil free air
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.44 g/L


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Municipal water of the city of Frankenthal, not chlorinated, charcoal filtered
- Ca/Mg ratio: 9:1
- Intervals of water quality measurement: after 1, 24, 48, 72 and 96 hours


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light : 8 hours dark

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality and symptoms after 1, 4, 24, 48, 72 and 96 hours


TEST CONCENTRATIONS
- Spacing factor for test concentrations: approximately 2.2
- Range finding study: yes
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

215 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

681.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: geometric mean of 464 and 1000 mg/L

Sublethal observations / clinical signs:

- Based on the nominal concentrations the median lethal concentration LC 50 (96 h) is > 460 < 1000 mg/l. Mortality occurred from the concentration 464 mg/L upward.

- Other substance-related effects were the symptoms escape reflex and swimming near the water surface.

- The mortality may be caused by the low oxygen content in the test solutions (oxygen consumption of the test substance).

- The no observed effect concentration NOEC (96 h) is 215 mg/l.

- Based on the analytically determined concentrations the median lethal concentration LC 50 (96 h) is > 500 < 1000 mg/l. The no observed effect concentration NOEC (96 h) is 236 mg/l.

- Analytically detected concentrations (sum of sulfite and sulfate) were initially 101.5-142.5% and after 96 h 99.1 - 120.0% of the nominal concentrations. At nominal concentrations of 1000 mg/l (464 mg/l), 220 mg/l (12 mg/l) sulfite and 614 mg/l (425 mg/l) sulfate were detected after 96 h.

Validity criteria fulfilled:

no

Remarks:

dissolved oxygen concentrations did not remain above 60% of the air saturation value in all test vessels at test start; no control mortality

Conclusions:

A standard acute fish toxicity test was conducted with Danio rerio (previous name: Brachydanio rerio), using potassium metabisulphite (K2S2O5) as test compound. A 96 h LC50 of 681.2 mg test item/L was derived as the geometric mean of 464 and 1000 mg test item/L, which corresponds to 490 mg sulfite/L. Dissolved oxygen concentrations dropped below 60% of the air saturation value (at 16 °C) at test concentrations of 215 to 1000 mg K2S2O5/L. Since the derived LC50 is within this concentration range, effects observed on the survival of D. rerio at this level are associated with indirect effects of oxygen depletion.

Reference 6

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study. Oxygen depletion of test medium at higher 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.

Guideline:

other: Bionomics Protocol for Freshwater Static Acute Toxicity Tests with Fish, December 1983

Principles of method if other than guideline:

This protocol closely follows 'Standard Practice for conducting acute toxicity tests with fishes, macroinvertebrates and amphibians' (ASTM, 1980).

GLP compliance:

not specified

Analytical monitoring:

no

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

The bluegill (Bionomics lot #85A33) were obtained from a commercial supplier in Missouri.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

51 mg/L as CaCO3

Test temperature:

22 +-1 °C

pH:

6.7-7.1

Dissolved oxygen:

range of 71-91% of saturation

Nominal and measured concentrations:

160, 260, 430, 720, 1200, 2000 mg/L

Details on test conditions:

The bluegill were held in a 1600L fiberglass tank under a photoperiod of 16 hours light and 8 hours darkness.

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

510

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: Lower and Upper confidence limits (340 and 740)

Reported statistics and error estimates:

moving average angle analysis

Sublethal observations / clinical signs:

Table: Dissolved oxygen at test start and test end and corresponding % air saturation values

Test item concentration [mg/L]	Dissolved oxygen [mg/L] (test start)	% air saturation	Dissolved oxygen [mg/L] (test end)	% air saturation
0	9.8	106	6.0	68
160	9.8	106	5.9	67
260	9.8	106	6.0	68
430	9.7	105	5.7	65
720	9.7	105	3.2	36
1200	9.7	105	(100 % mortality)	-
2000	9.7	105	(100 % mortality)	-

Conclusions:

Effects were tested of ammonium thiosulfate on Lepomis macrochirus. An LC50 of 510 mg/L was determined. This is reliable and can be further used for hazard/effects asessment purposes for ammonium thiosulfate and other thiosulfate compounds (read-actross principles)

Reference 7

Endpoint:

short-term toxicity to fish

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study; oxygen depletion of test medium at higher 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.

Guideline:

other: Bionomics Protocol for Freshwater Static Acute Toxicity Tests with Fish, December 1983

Principles of method if other than guideline:

This protocol closely follows 'Standard Practice for conducting acute toxicity tests with fishes, macroinvertebrates and amphibians' (ASTM, 1980). Protocol states that test organisms will not be fed during the 48- hours prior to testing. For this study the test organisms were fed during this period and is supposed not to affect the results of this study.

GLP compliance:

yes

Analytical monitoring:

no

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

The rainbow trout (Bionomics lot#85A38) were obtained from a commercial supplier in California

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

47 mg/L as CaCO3

Test temperature:

12 +- 1 °C

pH:

6.7-7.4

Dissolved oxygen:

Measured during test, no aeration

Nominal and measured concentrations:

130, 220, 360, 600, 1000 mg/L (nominal)

Details on test conditions:

The trout were held in a 500L fiberglass tank under a photoperiod of 16 hours light and 8 hours darkness.

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

770 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: Lower and Upper confidence limits 600 and 1000 mg/L

Reported statistics and error estimates:

Nonlinear interpolation with 95% confidence intervals calculated by binominal probability

Sublethal observations / clinical signs:

Table: Dissolved oxygen at test start and test end and corresponding % air saturation values

Test item concentration [mg/L]	Dissolved oxygen [mg/L] (test start)	% air saturation	Dissolved oxygen [mg/L] (test end)	% air saturation
0	8.1	76.9	6.8	64.5
130	8.1	76.9	5.5	52.2
220	8.0	75.9	5.7	54.1
360	8.1	76.9	5.1	48.4
600	8.1	76.9	3.4	32.3
1000	8.1	76.9	(100 % mortality)	-

Conclusions:

Effects were tested of ammonium thiosulfate on Salmo gairdneri. An LC 50 of 770 mg/L was determined. This is reliable and can be further used for hazard/effects asessment purposes for ammonium thiosulfate and other thiosulfate compounds (read-actross principles)

Description of key information

A 96 h LC50 of 62.3 mg Na2S2O4/L was derived in a standard acute fish toxicity test with Leuciscus idus using sodium dithionite as test compound. However, mortality was related to dithionite-induced oxygen depletion of the test medium at test start, with dissolved oxygen concentrations below 60 % saturation at all but the lowest test concentration. In studies withthiosulfate and sulfite/disulfite substances and controlled oxygen concentrations and pH, effect values are unbounded or above the OECD test limit of 100 mg/L(LC50 > 100 mg/L) and it is concluded that dithionite, sulfite/disulfite and thiosulfate substances are not acutely toxic to freshwater fish up to the OECD test limit. Furthermore, sodium as essential element has a very low potential for acute toxicity to freshwater and marine fish. Based on data available for sodium dithionite and read-across to thiosulfate and sulfite/disulfite substances and soluble sodium substances and taking into account ubiquitousness and essentiality of sodium and sulfur, the potential of sodium dithionite for acute toxicity to fish is expected to be low.

Additional information

One study on the short-term toxicity of sodium dithionite to fish is available with L. idus. In addition, read-across to dithionite, thiosulfate and sulfite/disulfite substances is applied. Upon contact with water, salts of sulfur oxyacids including sodium dithionite dissociate into sulfur oxyacid anions and the respective counterions. Only the properties of the dithionite anion are considered a relevant determinant of environmental toxicity since sodium cations are essential and have a very low potential for acute toxicity to freshwater and marine fish. Please refer to the respective endpoint summary for sodium (Na) for further details. Dithionite anions are unstable under environmentally relevant conditions and will rapidly disproportionate to (bi-)sulfites and thiosulfates (S₂O₃^2-) in aqueous media.Sulfites and thiosulfates are unstable in the environment, subject to transformation processes including oxidation to sulfate or reduction to sulfide, and will ultimately become part of the natural sulfur cycle.

 

Dithionite, thiosulfate and sulfite/disulfite substances –Short-term toxicity to fish

The acute toxicity to different fish species (Danio rerio (previous name: Brachydanio rerio), Oncorhynchus mykiss (previous name: Salmo gairdneri), Leuciscus idus and Lepomis macrochirus) was examined in one study with sodium dithionite, two studies with ammonium thiosulfate and four studies with sulfite and disulfite substances (i.e., potassium sulfite, potassium metabisulfite, disodium disulfite and sodium sulfite).

Table: Overview of the short-term toxicity of dithionite, thiosulfate and sulfite substances to freshwater fish

Test substance	Test species	96 h LC50 (mg test item/L)	96 h LC50 (mg SO3^2-/L)	Reference
sodium dithionite	Leuciscus idus	62.3	57.2	BASF, 1982
ammonium thiosulfate	Lepomis macrochirus	510	275.5	Springborn Binomics Inc, 1986
ammonium thiosulfate	Oncorhynchus mykiss	770	416	Springborn Binomics Inc, 1986
disodium disulfite	Oncorhynchus mykiss	177.8	149.6	BASF, 1981
sodium sulfite	Leuciscus idus	316	200.5	BASF, 1989
potassium sulfite	Leuciscus idus	316	159.7	BASF, 1989
potassium metabisulfite	Danio rerio	681.2	490	BASF, 1995

 

In the test with sodium dithionite, mortality was related to dithionite-induced oxygen depletion of the test medium at test start, with dissolved oxygen concentrations below 60 % saturation at all but the lowest test concentration and < 1 mg/l at higher test concentrations, which resulted in rapid mortality at the beginning of the test.

Similarly, in tests with sodium sulfite, potassium sulfite and potassium metabisulfite, mortality was related to sulfite-induced oxygen depletion of the test medium, i.e.concentrations that result in 100% mortality were not toxic when the medium was aerated during the test.

The lowest 96-h LC50 of 149.6 mg/L (expressed as sulfite (SO32-)) for sulfite/disulfite substances was identified for trout O. mykiss in a study with disodium disulfite. However, it cannot be excluded that observed mortality is caused by the very low pH of the test medium observed upon addition of the test substance. At a concentration of 215 mg/L (90% mortality), the pH decreased to a pH between 4.3 and 5.6 and is outside the “specified range” of pH 6.0 - 8.5 (OECD Guidance Document No. 23, 2019). It may, thus, be assumed that the “substance-specific” LC50 of sulfite substances for freshwater fish is above the LC50s derived in studies applying a test system with a limited buffering capacity for oxygen concentrations and pH.

Effects observed in tests with ammonium thiosulfate were only observed at concentrations substantially above the OECD test limit of 100 mg/L (OECD 203).

 

Since derived LC50 values were i) observed at test concentrations above the OECD test limit of 100 mg/L (OECD 203) and/or ii) presumably caused by oxygen depletion or a pH decrease and do not represent the intrinsic toxicity, it is concluded that dithionite, thiosulfate and sulfite/disulfite substances are not acutely toxic to freshwater fish.