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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Samples for analysis were taken from all test concentrations and the control on 4 occasions throughout the test, on fresh (D0, D7, D13 and D20) and old solutions (D1, D8, D14, D21) for each occasion. Samples were taken from the test vessels and filtered through 0.45 µm filters in order to remove any solid content. Samples were analysed immediately after collection.
Vehicle:
no
Details on test solutions:
No specificity. A typical daphnia medium was used.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test organisms used for this study was Daphnia magna Straus (Cladocera, Crustacea), clone 5, bred within the laboratory by acyclical parthenogenesis in a synthetic medium. The neonates used were less than 24h old at test initiation (selected by filtration) and were not first brood progeny. Test animals were fed a diet of 0.1 - 0.2 mg of carbon per daphnid per day, in the form of a suspension of the algal strains Chlorella vulgaris (25%) and Pseudokirchneriella subcapitata (75%), except during the initial three days of culture when a slightly lower ration was given.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
None.
Hardness:
170 - 180 as mg/L CaCO3
Test temperature:
19.2-20.1°C (min-max)
pH:
7.4 - 8.6 (min-max)
Dissolved oxygen:
8.5 - 10.3 mg/L (min-max)
Salinity:
Freshwater.
Nominal and measured concentrations:
Nominal: 0 ; 0.05 ; 0.15 ; 0.49 ; 1.53 ; 5 mg/L.
Concentrations were measured in all treatments in new and old media four times. All concentrations remained between 80 and 120% of the nominal concentration. Therefore, nominal concentrations were used for statistical analysis of the results.
Details on test conditions:
TEST SYSTEM
- Test vessel: tubes
- Material, size, headspace, fill volume: clear glass tubes (120 mL capacity), stoppered with cellulose bungs to minimise evaporation and dust.
- Aeration: None
- Semi-static: daily renewal, including weekends
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16L:8D
- Light intensity: 800 lux

EFFECT PARAMETERS MEASURED
- Number of dead parents per day
- Number of living neonates par day
- Age at first brood
Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.15 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
1.56 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
immobilisation
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
>= 5 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: age at first brood
Details on results:
All test solutions appeared clear and colourless. No precipitation of test item nor undissolved particles were observed. Test item concentrations remained between 80% and 120% of the nominal concentrations in each treatment group for each sampling time (both new ans old). Based on these results, the exposure concentrations used for statistical analysis were based on the nominal concentration.
The number of immobile adults Daphnia magna recorded during the reproduction test was 1 (10%) at 0.05 mg/L, 2 (20%) at 1.56 mg/L and 10 (100%) at 5 mg/L of test item. There were no immobile Daphnia magna parent in the control group or in the 0.15 or 0.49 mg/L treated groups.
The numbers of offspring produced for each concentration (0 ; 0.05 ; 0.15 ; 0.49 ; 1.56 ; 5 mg/L) during the test were respectively 105.5, 96.4, 90.6, 88.5, 2.8 and 0 living neonates per living parent at the test of the test (Table 1).
Temperature was maintained at 20 ± 1°C (measured temperatures: min. 19.2, max. 20.1°C and mean: 19.6°C).
Results with reference substance (positive control):
None.
Reported statistics and error estimates:
Nominal concentrations of test item in the test solutions were used in the estimation of ECx and NOEC/LOEC values. Analysed variables were number of living neonates produced per living parent at the end of the test, parent immobilisation and mean time to first brood. All statistical analysis were conducted using the Software ToxRat 2.10.

Table 1: parent immobilization and mean number of living neonate produced per surviving parents at the end of the test for each concentration tested (expressed as geometric means).

































Concentrations (mg/L)



Control



0.05



0.15



0.49



1.56



5



Mean number of neonates



105.5



96.4



90.6



88.5



2.8



---



Parent immobilization (%)



0



10



0



0



20



100



 


Table 2: mean number of neonates (living and dead), eggs and dead parent per day


 







































































































































































































































































































































































































































































































  J6J7J8J9J10J11J12J13J14J15J16J17J18J19J20J21
0Number of liv. neo00359717721480251437920961950128
Number of dead neo.002134450121050100
Number of egg0002106002001400
Number of dead0000000000000000
0,05Number of liv. neo003979205592660162420991086939
Number of dead neo.0038235402000320
Number of egg0000001604101100
Number of dead0000100000000000
0,15Number of liv. neo0038730471680019756012120600
Number of dead neo.001035042800414001300
Number of egg00570410009200900
Number of dead0000000000000000
0,49Number of liv. neo0037630711121924154270113184081
Number of dead neo.0021180911200217021400
Number of egg003110513633112051600
Number of dead0000000000000000
1,56Number of liv. neo000000000100001200
Number of dead neo.0000003006000400
Number of egg000150060180001300
Number of dead1000000000000000
5Number of liv. neo0000000000000000
Number of dead neo.0000000000000000
Number of egg0000000000000000
Number of dead0401500000000000

 


Table 3: total number of neonates (living and dead), eggs and dead parents











































































































0Total liv. neo1055
Total dead neo.47
Total egg16
Total dead0
0,05Total liv. neo870
Total dead neo.32
Total egg14
Total dead1
0,15Total liv. neo906
Total dead neo.108
Total egg46
Total dead0
0,49Total liv. neo885
Total dead neo.114
Total egg105
Total dead0
1,56Total liv. neo22
Total dead neo.13
Total egg43
Total dead2
5Total liv. neo0
Total dead neo.0
Total egg0
Total dead10
Validity criteria fulfilled:
yes
Conclusions:
The toxicity of 1,3-diphenyl-2-thiourea was tested on Daphnia magna reproduction according to the OECD 211 guideline. The lowest NOEC was 0.15 mg/L.
Executive summary:

This study was designed to determine the effects of 1,3 -diphenyl-2 -thiourea on Daphnia magna reproduction and survival in a 21 days test according to the OECD 211 Guideline. The total test period was 21 days; all test solutions (including control) were renewed every day (including "weekend" periods). Ten replicate test vessels were prepared for the control and the test concentration. A single juvenile Daphnia magna (<24 hours old selected by filtration) was added to each test vessel. Each day, parental animals were transferred into freshly prepared test media. Dead parents were noted and discarded. All produced juveniles were counted every day. Chemical analysis of test samples confirmed the stability of the substance over a 24-hour test period. Based on these results, the exposure concentrations were based on the nominal concentration. NOEC and LOEC values on day 21 were determined as follows:

NOEC for mean number of neonate produced per parent alive at the end of the test: 0.15 mg/L

NOEC for mobility: 1.56 mg/L

NOEC for age at first reproduction: > 5 mg/L.

Description of key information

The chronic toxicity was assessed according to the OECD 211 guideline.
21d-NOEC = 0.15 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.15 mg/L

Additional information

This study was designed to determine the effects of 1,3 -diphenyl-2 -thiourea on Daphnia magna reproduction and survival in a 21 days test according to the OECD 211 Guideline. The total test period was 21 days; all test solutions (including control) were renewed every day (including "weekend" periods). Ten replicate test vessels were prepared for the control and the test concentration. A single juvenile Daphnia magna (<24 hours old selected by filtration) was added to each test vessel. Each day, parental animals were transferred into freshly prepared test media. Dead parents were noted and discarded. All produced juveniles were counted every day. Chemical analysis of test samples confirmed the stability of the substance over a 24-hour test period. Based on these results, the exposure concentrations were based on the nominal concentration. NOEC and LOEC values on day 21 were determined as follows:

NOEC for mean number of neonate produced per parent alive at the end of the test: 0.15 mg/L

NOEC for mobility: 1.56 mg/L

NOEC for age at first reproduction: > 5 mg/L.