Hydrogen peroxide-urea

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

according to guideline

Guideline:

other: DIN 38412 Teil 11 (modified)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

The test substance was quantitatively dissolved in the test medium until optically clear, by means of a magnetic mixer in closed containers. The pH of the test solution was not adjusted.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna straus, of the IRCHA strain.
Cultures were held in 2 litre beakers filled with at least 1.6 litres of tap water. A total of 60 cultures were prepared, producing 24 hour old animals daily. The mother animals from these cultures were transferred daily (Monday to Friday) into freshly prepared culture glasses by means of wide-mouthed pipettes. The young animals produced from Tuesday to Friday of each week were accumulated daily on a DIN sieve 0.315 mm and used at test organisms. The young animals produced from Friday to Monday of each week were separated according to size using test sieves DIN 0.630 and 0.315 mm. The size classes were cultivated separately for breeding purposes. The gaps which occurred in the group of mother animals were filled from these animals which were kept in separate supply. Those which could be sifted out on a DIN test sieve 1.25 mm were used when the number of mother animals began to decrease below 30 per glass.
All culture glasses were covered with hour glasses and kept on white table tops. The cultures were fed daily. On Monday and Friday of each week the tap water for each culture was renewed, on Friday the culture glass was also replaced. This was done at the same time as the selective removal of animals.
The culture water was tempered, chlorine free, oxygen saturated tap water (hardness 16° d.H., pH 7.6-7.7). Tap water was used 24 hours after it was drawn, and the tap had run for a minimum of 1 hour prior to drawing.
Standardised dry feed "Mikrozell" was fed to the standard cultures. It was suspended 30 g/L of tap water and 10 mL suspension was added to each culture glass.
The temperature of the holding room was maintained at 20 °C. The room was illuminated for 9 hours per day by means of Osram fluorescent tubes, colour 25 (room illumination intensity 2.5 W/m²); daylight was screened out.

- Culture medium: Prepared according ot DIN38412 Teil 11. Same as ISO Medium (OECD 202).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Hardness:

16° d.H.

Test temperature:

20 °C

pH:

7.6 - 7.7

Dissolved oxygen:

The test water was aerated to the oxygen saturation value.

Nominal and measured concentrations:

Dilution series in ratios of 1:2, 1:1,14 etc.

Details on test conditions:

The sum of calcium and magnesium ions in the artificial test water was 2.5 mmole/litre. The molar ratio of sodium to potassium ions was 10:1.
As test vessels 50 mL beackers were used.
Artificial test water (test medium) was used for the toxicity test. The test substance was quantitatively dissolved in the test medium until optically clear, by means of a magnetic mixer in closed containers. The test mixtures were prepared as a double parallel dilution series, each with ten 24 hour old Daphnia per culture vessel. The vessels were covered with a loose layer of filter paper and were kept in an incubation cabinet for 24 hours at 20 °C. At the end of the exposure period, the animals that could still swim were counted.
The pH and the oxygen content was measured in the test and control vessels at the end of the test period.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Results with reference substance (positive control):

The average EC50 of Potassium dichromate was 1.3 mg/L (acceptable range 0.9 - 1.9 mg/L).

Reported statistics and error estimates:

The Schleicher and Schuell probablility network was used, calculation of 95 % confidence limits and Chi-square were performed.

Validity criteria fulfilled:

yes

Conclusions:

The 24-hour EC50 for Daphnia magna was determine to be >10000 mg/L. Therefore, urea is not acutely toxic to daphnids.

Executive summary:

An experiment according to DIN 38412 Teil 11 was perfomed with differen urea solutions to determine the toxicity to Daphnia magna in 24-h exposure scenario. Ten young daphnids were exposed to the test solutions for 24 hours. The mobility of the daphnids was determine at the end of the test. The EC50 and EC100 were determined to be >10000 mg/L. Therefore, urea is not toxic to daphnids.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPP 72-3 (Estuarine/Marine Fish, Mollusk, or Shrimp Acute Toxicity Test)

Principles of method if other than guideline:

Exposure of urea to freshwater snails over 3 life stages; eggs, juveniles and adults.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

A 10 % stock solution of urea was made by dissolving 10 grams of the chemical with Kentwood Spring water (commercialized well water) in 100 mL solution.

Test organisms (species):

other aquatic mollusc: Helisoma trivolvis

Details on test organisms:

Helisoma trivolvis eggs, juveniles (3 - 5 mm) and adults (8 - 10 mm). Snails were from Louisiana, USA.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Nominal and measured concentrations:

Nominal concentrations ranging from approximately 6000 to 50000 mg/L.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

13 477 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: adults

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

14 241 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: eggs

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

18 254 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: juveniles

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

22 998 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: adults

Duration:

48 h

Dose descriptor:

other: LC95

Effect conc.:

20 608 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: adults

Details on results:

The 24-hour LC50 values for eggs, juveniles and adults were 14241 mg/L, 18255 mg/L and 22998 mg/L, respectively. Following 48-hours exposure, the LC95 value for adults was 20608 mg/L. Following 48 hours exposure, the LC50 value for adults was calculated to be 13477 mg/L.

Reported statistics and error estimates:

Percent mortality was plotted against concentration and the slope determined along with 95 % confidence limits (Probit method).

The eggs appeared to be more sensitive to urea toxicity than the juveniles which also showed a higher susceptibility than the adults. Reduced amounts of urea were required for a given percent kill during longer exposure times as expected. The concentrations of urea affecting snail mortality during 24 h and 48 h of exposure were hundreds of times higher than the field doses typically applied for increasing crop yield. Thus, from a practical standpoint urea possesses a very low molluscicidal activity.

Validity criteria fulfilled:

not applicable

Conclusions:

The 24-hour LC50 values for eggs, juveniles and adults were 14241 mg/L, 18255 mg/L and 22998 mg/L, respectively. Following 48-hours exposure, the LC95 value for adults was 20608 mg/L. Following 48 hours exposure, the LC50 value for adults was calculated to be 13477 mg/L. Under normal laboratory conditions, urea displays a low molluscicidal activity.

Executive summary:

A study with freshwater snails Helisoma trivolvis was performed in order to test the short-term toxicity of urea on aquatic invertebratres. Eggs, juveniles and adults were exposed to urea in concentrations from 6000 to 50000 mg/L for 48 hours. The mortality was noted after 24 and 48 hours. The 24-hour LC50 values for eggs, juveniles and adults were 14241 mg/L, 18255 mg/L and 22998 mg/L, respectively. Following 48-hours exposure, the LC95 value for adults was 20608 mg/L. Following 48 hours exposure, the LC50 value for adults was calculated to be 13477 mg/L. Under normal laboratory conditions, urea displays a low molluscicidal activity.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPP 72-3 (Estuarine/Marine Fish, Mollusk, or Shrimp Acute Toxicity Test)

Principles of method if other than guideline:

Exposure of urea to freshwater snails over 3 life stages; eggs, juveniles and adults.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

A 10 % stock solution of urea was made by dissolving 10 grams of the chemical with Kentwood Spring water (commercialized well water) in 100 mL solution.

Test organisms (species):

other aquatic mollusc: Biomphalaria havanensis

Details on test organisms:

Biomphalaria havanensis at 3 life stages; eggs, juveniles (2 - 3 mm) and adults (5 - 6 mm). Snails were from the Dominican Republic.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Nominal and measured concentrations:

Nominal concentrations ranging from approximately 6000 to 50000 mg/L.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

21 412 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: adults

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

13 532 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: eggs

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

24 504 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: juveniles

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

26 024 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: adults

Duration:

48 h

Dose descriptor:

other: LC95

Effect conc.:

36 998 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: adults

Details on results:

The 24-hour LC50 values for eggs, juvenile and adult snails were 13532 mg/L, 24504 mg/L and 26024 mg/L, respectively. Following 48 hours exposure, the LC95 value for adults was 36998 mg/L and the LC50 value for adults was calculated to be 21412 mg/L.

Reported statistics and error estimates:

Percent mortality was plotted against concentration and the slope determined along with 95 % confidence limits (Probit method).

The eggs appeared to be more sensitive to urea toxicity than the juveniles which also showed a higher susceptibility than the adults. Reduced amounts of urea were required for a given percent kill during longer exposure times as expected. The concentrations of urea affecting snail mortality during 24 h and 48 h of exposure were hundreds of times higher than the field doses typically applied for increasing crop yield. Thus, from a practical standpoint urea possesses a very low molluscicidal activity.

Validity criteria fulfilled:

not applicable

Conclusions:

The 24-hour LC50 values for eggs, juvenile and adult snails were 13532 mg/L, 24504 mg/L and 26024 mg/L, respectively. Following 48 hours exposure, the LC95 value for adults was 36998 mg/L and the LC50 value for adults was calculated to be 21412 mg/L. Under normal laboratory conditions, urea displays a low molluscicidal activity.

Executive summary:

A study with freshwater snails Biomphalaria havanensis was performed in order to test the short-term toxicity of urea on aquatic invertebratres. Eggs, juveniles and adults were exposed to urea in concentrations from 6000 to 50000 mg/L for 48 hours. The mortality was noted after 24 and 48 hours. The 24-hour LC50 values for eggs, juvenile and adult snails were 13532 mg/L, 24504 mg/L and 26024 mg/L, respectively. Following 48 hours exposure, the LC95 value for adults was 36998 mg/L and the LC50 value for adults was calculated to be 21412 mg/L. Under normal laboratory conditions, urea displays a low molluscicidal activity.

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

according to guideline

Guideline:

other: DIN 38412 Teil 11 (modified)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

no

Specific details on test material used for the study:

Hydrogen peroxide, H2O2
CAS 7722-84-1
30 % solution

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

The test substance was quantitatively dissolved in the test medium until optically clear, by means of a magnetic mixer in closed containers. The pH of the test solution was not adjusted.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna straus, of the IRCHA strain.
Cultures were held in 2 litre beakers filled with at least 1.6 litres of tap water. A total of 60 cultures were prepared, producing 24 hour old animals daily. The mother animals from these cultures were transferred daily (Monday to Friday) into freshly prepared culture glasses by means of wide-mouthed pipettes. The young animals produced from Tuesday to Friday of each week were accumulated daily on a DIN sieve 0.315 mm and used at test organisms. The young animals produced from Friday to Monday of each week were separated according to size using test sieves DIN 0.630 and 0.315 mm. The size classes were cultivated separately for breeding purposes. The gaps which occurred in the group of mother animals were filled from these animals which were kept in separate supply. Those which could be sifted out on a DIN test sieve 1.25 mm were used when the number of mother animals began to decrease below 30 per glass.
All culture glasses were covered with hour glasses and kept on white table tops. The cultures were fed daily. On Monday and Friday of each week the tap water for each culture was renewed, on Friday the culture glass was also replaced. This was done at the same time as the selective removal of animals.
The culture water was tempered, chlorine free, oxygen saturated tap water (hardness 16° d.H., pH 7.6-7.7). Tap water was used 24 hours after it was drawn, and the tap had run for a minimum of 1 hour prior to drawing.
Standardised dry feed "Mikrozell" was fed to the standard cultures. It was suspended 30 g/L of tap water and 10 mL suspension was added to each culture glass.
The temperature of the holding room was maintained at 20 °C. The room was illuminated for 9 hours per day by means of Osram fluorescent tubes, colour 25 (room illumination intensity 2.5 W/m²); daylight was screened out.

- Culture medium: Prepared according ot DIN38412 Teil 11. Same as ISO Medium (OECD 202).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Hardness:

16° d.H.

Test temperature:

20 °C

pH:

7.6 - 7.7

Dissolved oxygen:

The test water was aerated to the oxygen saturation value.

Nominal and measured concentrations:

The test item was tested in 30 % solution.

Details on test conditions:

The sum of calcium and magnesium ions in the artificial test water was 2.5 mmole/litre. The molar ratio of sodium to potassium ions was 10:1.
As test vessels 50 mL beackers were used.
Artificial test water (test medium) was used for the toxicity test. The test substance was quantitatively dissolved in the test medium until optically clear, by means of a magnetic mixer in closed containers. The test mixtures were prepared as a double parallel dilution series, each with ten 24 hour old Daphnia per culture vessel. The vessels were covered with a loose layer of filter paper and were kept in an incubation cabinet for 24 hours at 20 °C. At the end of the exposure period, the animals that could still swim were counted.
The pH and the oxygen content was measured in the test and control vessels at the end of the test period.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

7.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: 95 % CI: 6.7 - 8.7 mg/L

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

0.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Results with reference substance (positive control):

The average EC50 of Potassium dichromate was 1.3 mg/L (acceptable range 0.9 - 1.9 mg/L).

Reported statistics and error estimates:

The Schleicher and Schuell probablility network was used, calculation of 95 % confidence limits and Chi-square were performed.

Validity criteria fulfilled:

yes

Conclusions:

The 24-hour EC50 for Daphnia magna was determine to be 7.7 mg/L. The EC0 was 0.9 mg/L and the EC100 was 15 mg/L.

Executive summary:

An experiment according to DIN 38412 Teil 11 was perfomed with differen hydrogen peroxide solutions to determine the toxicity to Daphnia magna in 24-h exposure scenario. Ten young daphnids were exposed to the test solutions for 24 hours. The mobility of the daphnids was determine at the end of the test. The EC50 was determined to be 7.7 mg/L. The EC0 was 0.9 mg/L and the EC100 was 15 mg/L.

Reference 5

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Principles of method if other than guideline:

The acute toxicity of H2O2 to two freshwater invertebrate species (Daphnia carinata and Moina sp.) was determined in static dose-response tests.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

At the start of the test, H2O2 was slowly injected into the test vessel and mixed gently.

Test organisms (species):

other: Daphnia carinata and Moina sp.

Details on test organisms:

1. Freshwater waterflea Daphnia carinata (sensu lato)
Source: Wundowie wastewater treatment plant / Western Australia,
2. Freshwater waterflea Moina sp.
Source: Sir James Mitchell Park Pond, Perth / Western Australia

- Clonal cultures from wild caught
- Adult with fully developed brood chambers, no age indicated
- Food: Desmodesmus sp. (Chlorophyta) [Commonwealth Scientific and Industrial Research Organization (CSIRO): CS-899]. Food concentration was 1 mg carbon equivalent, calculated from a calibration curve correlating the particulate organic carbon (POC) of Desmodesmus to the absorption of the culture
- Feeding of animals during test: ad libitum

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

21 °C

Nominal and measured concentrations:

Nominal test concentrations were:
1, 2, 3, 4, 5, 6, 7, 8, 12.5, 20, 30, 40, 125, 1250 and 12500 mg/L for Daphnia
1, 1.5, 2, 3, 4, 5, 7.5, 10, 12.5, 68.75, 125, 1250 and 12500 mg/L for Moina.
The concentration of the test substance in the treatments was not analysed.

Details on test conditions:

- Test type: static
- Volume of test vessels / test medium: Volume and type of test vessel not presented / 500 mL
- Test medium: 1.2 μm filtered water from the mesotrophic Jackadder Lake (Perth / West Australia)
- Volume/animal: 25 mL
- Number of animals/vessel: 20
- Number of vessels/ concentration: 3
- Test performed in closed vessels due to significant volatility of TS: Not specified but potential for specific properties of the test substance was taken into account by the dosing procedure (i.e. test substance was injected into the test water of each test vessel at test start and afterwards gently mixed)
- Photoperiod: dark: light cycle of 12/12 h
- Intensity of irradiation: Low-fluorescent light conditions (prevention of H2O2 degradation and to avoid any effects of UV light on the two study organisms)

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: Daphnia

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: Daphnia: 95% confidence range: 5.0 - 6.3 mg/L, probit analysis

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

1.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: Moina sp.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: Moina: 95% confidence range: not calculated due to the small number if concentrations with less than 100% mortality; probit analysis

Details on results:

The two study organims were sensitiv to H2O2, but Daphnia was less susceptible than Moina. In the first 12 h, Monia showed 100 % mortality with concentration ≥ 6 mg H2O2/L. The respective concentration for Daphnia was >40 mg H2O2/L. No effect was observed at 3 and 1.5 mg/L for Daphnia and Monia (NOEC). The varied sensitivity between Daphnia and Moina were probably because of physiological differences, such as different activity levels of enzymes (e.g., catalase, peroxidase) or body size (Moina is much smaller in size in comparison to Daphnia). Purpose of this study was to identify the range of reactions of two zooplankton species in wastewater stabilization ponds (WSPs) to different concentrations of H2O2.

Reported statistics and error estimates:

LC50 values and the 95 % confidence limits were calculated using probit analysis and linear regression models (PASW Statistics 18, Bliss 1935). To calculate the NOEC, the proportion of individuals surviving after 48 h were compared with one-way ANOVA (PASW Statistics 18). Differences in the survival of Daphnia and Moina were calculated with the Kaplan-Meier log-rank test. The significance level was set to P < 0.05, deviation are stated.

Validity criteria fulfilled:

not applicable

Conclusions:

The EC50 of Daphnia carinata was determine to be 5.6 mg/L after 48 h with an 95 % confidence range of 5.0 - 6.3 mg/L. The EC50 for Moina sp. was determined to be 2.0 mg/L after 48 h.

Executive summary:

A study similar to OECD 202 was perfomed with the freshwater crustacean species was performed in order to determine the toxicity of hydrogen peroxide on aquatic invertebrates. Daphnia carinata and Moin sp. were tested in a 48-h static test. Both test organisms were exposed to a series of test concentrations - for Moin sp. 14 concentrations were tested and for Daphnia carinata 16 test concentrations were tested. After 48-h exposure period the mortality was determined. It was determined that after 12 hours exposure Moin sp. showed up to 100 % mortality. The 48-h EC50 for Daphnia carinata was determined to be 5.6 mg/L and for Moin sp. this value was 2 mg/L. The lower toxicity for Moina sp. is most likely due to the smaller size of the organisms compared to the daphnids.

Reference 6

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to section 13 for "Read-Across justification".

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: Daphnia magna

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

13 477 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: freshwater adult snails Helisoma trivolvis

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

21 412 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality

Remarks on result:

other: freshwater adult snails Biomphalaria havanensis

Reference 7

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to section 13 for "Read-Across justification".

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

7.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Remarks on result:

other: Daphnia magna

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Daphnia carinata

Description of key information

The short-term toxicity to aquatic invertebrates was determined with respect to H2O2, as this degradation product of the test item showed the most toxic effects on the tested animals. The other degradation product, urea, is not toxic to aquatic invertebrates. Therefore, the LD50 was determined to be 5.6 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

5.6 mg/L

Additional information

The short-term toxicity to aquatic invertebrates of the test item was addressed with a read-across approach to its degradation products - urea and hydrogen peroxide. The test item is not stable and decomposes rapidly to urea and H2O2, therefore, the read-across to both substances is considered acceptable.

Publications reporting the short-term toxicity to aquatic invertebrates of urea and hydrogen peroxide were used in a read-across weight of evidence approach.

Urea

An experiment according to DIN 38412 Teil 11 was perfomed with different urea solutions to determine the toxicity to Daphnia magna in 24-h exposure scenario. Ten young daphnids were exposed to the test solutions for 24 hours. The mobility of the daphnids was determine at the end of the test. The EC50 and EC100 were determined to be >10000 mg/L. Therefore, urea is not toxic to daphnids.

Another study with freshwater snails Helisoma trivolvis was performed in order to test the short-term toxicity of urea on aquatic invertebratres. Eggs, juveniles and adults were exposed to urea in concentrations from 6000 to 50000 mg/L for 48 hours. The mortality was noted after 24 and 48 hours. The 24-hour LC50 values for eggs, juveniles and adults were 14241 mg/L, 18255 mg/L and 22998 mg/L, respectively. Following 48-hours exposure, the LC95 value for adults was 20608 mg/L. Following 48 hours exposure, the LC50 value for adults was calculated to be 13477 mg/L. Under normal laboratory conditions, urea displays a low molluscicidal activity.

In the same study freshwater snails Biomphalaria havanensis were exposed to urea in order to determine the toxic effects on aquatic invertebratres. Eggs, juveniles and adults were exposed to urea in concentrations from 6000 to 50000 mg/L for 48 hours. The mortality was noted after 24 and 48 hours. The 24-hour LC50 values for eggs, juvenile and adult snails were 13532 mg/L, 24504 mg/L and 26024 mg/L, respectively. Following 48 hours exposure, the LC95 value for adults was 36998 mg/L and the LC50 value for adults was calculated to be 21412 mg/L. Under normal laboratory conditions, urea displays a low molluscicidal activity.

Hydrogen peroxide (H2O2)

An experiment according to DIN 38412 Teil 11 was perfomed with different hydrogen peroxide solutions to determine the toxicity to Daphnia magna in 24-h exposure scenario. Ten young daphnids were exposed to the test solutions for 24 hours. The mobility of the daphnids was determined at the end of the test. The EC50 was determined to be 7.7 mg/L. The EC0 was 0.9 mg/L and the EC100 was 15 mg/L.

A study similar to OECD 202 was perfomed with the freshwater crustacean species was performed in order to determine the toxicity of hydrogen peroxide on aquatic invertebrates. Daphnia carinata and Moin sp. were tested in a 48-h static test. Both test organisms were exposed to a series of test concentrations - for Moin sp. 14 concentrations were tested and for Daphnia carinata 16 test concentrations were tested. After 48-h exposure period the mortality was determined. It was determined that after 12 hours exposure Moin sp. showed up to 100 % mortality. The 48-h EC50 for Daphnia carinata was determined to be 5.6 mg/L and for Moin sp. this value was 2 mg/L. The lower toxicity for Moina sp. is most likely due to the smaller size of the organisms compared to the daphnids.

In conclusion, urea showed minimal effects on the tested freshwater snails. The LC50 vlaues for the tested species were determine to be very high. No effects on Daphnia magna were observed. Therefore, urea is not considered toxic to aquatic invertebrates. The toxicity profile of hydrogen peroxide-urea (1:1) is then based on the toxicity of H2O2, as H2O2 is the degradation product which showed significant effects on aquatic invertebrates. The EC50 to Daphnia carinata was determined to be 5.6 mg/L after 48 hours and this value was chosed as the key value and used for further assessment.