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Short-term toxicity to fish

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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.
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.
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.
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.
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)
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

Sulfite/disulfite and thiosulfate substances are not acutely toxic to freshwater fish up to the OECD test limit of 100 mg/L (LC50 > 100 mg/L). Furthermore, potassium as essential element has a very low potential for acute toxicity to freshwater and marine fish. Based on read-across to sulfite/disulfite/thiosulfate substances and soluble potassium substances and taking into account ubiquitousness and essentiality of potassium and sulfur, the potential of potassium sulfite for acute toxicity to fish is expected to be low.

Key value for chemical safety assessment

Additional information

One study on the short-term toxicity of potassium sulfite to fish is available with Leuciscus idus (BASF, 1989). In addition, read-across to sulfite/disulfite and thiosulfate substances is applied. Upon contact with water, salts of sulfur oxyacids including potassium sulfite dissociate into sulfur oxyacid anions and the respective counterions. Only the properties of the sulfite anion are considered a relevant determinant of environmental toxicity since the potassium 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 potassium (K) for further details.

Sulfite/disulfite and thiosulfate 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 four reliable studies with sulfite and disulfite substances (i.e. potassium sulfite, dipotassium disulfite, disodium disulfite and sodium sulfite) and two reliable studies with ammonium thiosulfate.

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

Test substance

Test species

96 h LC50 (mg test item/L)

96 h LC50 (mg SO32-/L)

Reference

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

dipotassium disulfite

Danio rerio

681.2

490

BASF, 1995

ammonium thiosulfate

Lepomis macrochirus

510

275.5

Springborn Binomics Inc, 1986

ammonium thiosulfate

Oncorhynchus mykiss

770

416

Springborn Binomics Inc, 1986

 

In tests with sodium sulfite, potassium sulfite and dipotassium disulfite, 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-)) 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.

 

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