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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1985
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Qualifier:
according to guideline
Guideline:
other: "Prolonged toxicity for Daphnia magna" EEC Directive 79/831, Methods for the Determination of Ecotoxicity - Level 1
GLP compliance:
not specified
Analytical monitoring:
not specified
Details on sampling:
No data.
Vehicle:
no
Details on test solutions:
No details reported.
Test organisms (species):
Daphnia magna
Details on test organisms:
No details reported.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
Not applicable.
Hardness:
No data.
Test temperature:
18-22 °C
pH:
No data.
Dissolved oxygen:
No data.
Salinity:
Not applicable.
Nominal and measured concentrations:
Not reported.
Details on test conditions:
No details reported.
Reference substance (positive control):
yes
Remarks:
potassium dichromate (test substance in test programm investigating the toxicfity of 25 substances)
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 0.1 - <= 0.25 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
No further results reported.
Results with reference substance (positive control):
NOEC (21 d) = 0.01-0.1 mg/L
Validity criteria fulfilled:
not specified
Conclusions:
The 21-d NOEC based on lethal effects, reproduction and further observed effects is reported to be in the range of 0.1 to 0.25 mg thiourea/L.
Executive summary:

The 21-day chronic toxicity of thiourea to Daphnia magna was studied under semi-static conditions.


The lowest 21 day NOEC based on lethal effects, reproduction and other observed effects was 0.1 mg/L.


This study is used in a weight-of-evidence approach to fulfill the REACH information requirements for long-term toxicity to invertebrates.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
no data
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method C.20 (Daphnia magna Reproduction Test)
GLP compliance:
not specified
Analytical monitoring:
not specified
Details on sampling:
No details reported.
Vehicle:
no
Details on test solutions:
No details reported.
Test organisms (species):
Daphnia magna
Details on test organisms:
- Age at beginning of test: < 24 h.
- Feeding during test: daily (suspension of baker's yeast and water)
- No further details reported.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
No details reported.
Test temperature:
No details reported.
pH:
No details reported.
Dissolved oxygen:
No details reported.
Salinity:
No details reported.
Nominal and measured concentrations:
Nominal concentrations: 0, 0.2, 0.8, 2.5, 8, 25 mg/L.
Details on test conditions:
TEST SYSTEM
- Renewal rate of test solution: three times a week (Monday, Wednesday, Friday)


TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: Monday, Wednesday, Friday (results not reported)

Reference substance (positive control):
not specified
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
< 0.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Details on results:
- Time to first brood release (control an all test concentrations - Immobility of parent animals: at 25 mg/L all parent animals immobile prior to first brood.
- At 8 mg/L: no offspring and 83% immobile parent animals.
- < 8 mg/L: no harmful effects
- Reproduction rate: at
Results with reference substance (positive control):
No details reported.
Reported statistics and error estimates:
No details reported.
Validity criteria fulfilled:
no
Remarks:
Number of offspring in control is too low
Conclusions:
The 21-d NOEC of thiourea for Daphnia magna is < 0.25 mg/L..
Executive summary:

The 21-day-chronic toxicity of thiourea to Daphnia magna was studied under semi-static conditions. Daphnids were exposed to control and test chemical at concentrations 0.2, 0.8, 2.5, 8, and 25 mg/L.

The lowest 21 day NOEC based on reproduction was <0.25 mg/L.

Production of offspring in the treated groups indicated that thiourea had an effect on the reproduction at concentrations greater than 2.5 mg/L.

This study is used in a weight-of-evidence approach to fulfill the REACH information requirements for long-term toxicity to invertebrates.

Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
no data
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Remarks:
Documentation insufficient for assessment (purity of the test substance is not reported; no details on test conditions and results).
Qualifier:
according to guideline
Guideline:
other: EEC-Directive 79/831: "Prolonged Toxicity for Daphnia magna" Rev. 1
GLP compliance:
no
Analytical monitoring:
not specified
Details on sampling:
no data
Vehicle:
no
Details on test solutions:
no details reported.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: IRCHA
- Source: own breeding at Environmental Protection Agency (UBA) Berlin
- Feeding during test:
* daily with Tetramin (2 g/L);
* Days 0-7: 0.2 mL/parent animal and day
* Days 8-20: 0.3 mL/parent animal and day
* in order to fulfill all testing criteria it was necessary to additionally feed sewage from the aeration tank of the municipal WWTP at 0.2 mL/parent animal and day


ACCLIMATION: not necessary due to continuous breeding in the testing laboratory
- Acclimation period:


METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
- altogether 40 cultures which produced daily 24-h old juveniles;
- parent animals were daily separated from juveniles by use of a pipette with large inner diameter
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
no data
Test temperature:
20 +/- 1 °C
pH:
no data
Dissolved oxygen:
> 65 % oxygen saturation
Salinity:
no data
Conductivity:
no data
Nominal and measured concentrations:
no data
Details on test conditions:
TEST SYSTEM
- Test vessel: 400 mL beakers
- Type: closed with watchglass
- Material, size, headspace, fill volume: glass; 250 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4-5
- 3 different test series that were started at different time points

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: no data
- Light intensity: no data

EFFECT PARAMETERS MEASURED: mortality of parent animals and reproduction rate
Reference substance (positive control):
no
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: mortality of parent animals and reproduction
Remarks on result:
other: Result of first test series.
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: mortality of parent animals and reproduction
Remarks on result:
other: Result of second and third test series. Second test series did not fulfil the validity criteria (40 offspring/parent animal after 21 d in the control cultures).
Details on results:
No details reported.
Reported statistics and error estimates:
Student t-test was used for data evaluation.
Validity criteria fulfilled:
not applicable
Remarks:
"yes" for first and third test series; "no" for second test series
Conclusions:
The lowest 21-d NOEC observed for thiourea was 0.25 mg/L.
Executive summary:

The 21-day-chronic toxicity of thiourea to Daphnia magna was studied under semi-static conditions. Daphnids were exposed to control and test chemical at several concentrations (no details reported). Three independent test series were conducted.


 


The lowest 21 day NOEC based on mortality of the parent animals and reproduction was 0.25 mg./L.


Production of offspring in the treated groups indicated that thiourea had an effect on the reproduction at concentrations greater than 0.25 mg/L.


 


This study is used in a weight-of-evidence approach to fulfill the REACH information requirements for long-term toxicity to invertebrates.

Description of key information

Three studies are available regarding the long-term toxicity of thiourea to invertebrates. These three studies are rated Klimisch III due to deficiencies regarding the documentation of the methods and results. However, as all three studies are reporting results for the long-term toxicity of thiourea to Daphnia magna that are in the same range, the studies are used in the assessment of thiourea in a weight-of-evidence approach:
- Broecker et al. (1984): NOEC < 0.25 mg/L
- Friesel et al. (1984): NOEC = 0.25 - 1 mg/L
- Boje & Rudolph (1985): NOEC = 0.1 - 0.25 mg/L
Due to precautionary principles the lowest reported result of NOEC (21-d) = 0.1 mg/L is used in the assessment of thiourea.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
NOEC
Effect concentration:
0.1 mg/L

Additional information

Three studies are available regarding the long-term toxicity of thiourea to invertebrates. These three studies are rated Klimisch III due to deficiencies in documentation of the methods and results. However, as all three studies report results on the long-term toxicity of thiourea to Daphnia magna that are in the same range, the studies are used in the assessment of thiourea in a weight-of-evidence approach.


 


Friesel et al. (1984) studied the 21-day chronic toxicity of thiourea to Daphnia magna under semi-static conditions. Daphnids were exposed to control and test chemical at several concentrations (no details reported). Three independent test series were conducted. The lowest 21 day NOEC based on mortality of the parent animals and reproduction was 0.25 mg/L. Production of offspring in the treated groups indicated that thiourea had an effect on reproduction at concentrations greater than 0.25 mg/L.


 


Broecker et al. (1984) also investigated the 21-day chronic toxicity of thiourea to Daphnia magna under semi-static conditions. Daphnids were exposed to control and test chemical at concentrations 0.2, 0.8, 2.5, 8, and 25 mg/L. The lowest 21 day NOEC based on reproduction was < 0.25 mg/L. Production of offspring in the treated groups indicated that thiourea had an effect on reproduction at concentrations greater than 2.5 mg/L.


 


Boje & Rudolph (1985) report the following results for the 21-day chronic toxicity of thiourea to Daphnia magna under semi-static conditions: The lowest 21 day NOEC based on lethal effects, reproduction and other observed effects was 0.1 mg/L.


 


Applying the precautionary principle, the lowest reported NOEC (21 d) of 0.1 mg/L is used in the hazard assessment of thiourea.