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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Refer to the analogue approach justification document provided in IUCLID section 13.
Reason / purpose:
read-across source
Related information:
Composition 1
Test material information:
Composition 1
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other:
Remarks:
Source: CAS 10023-48-0, Gado & Broschard, 2017
Conclusions:
The key value retained for the assessment of the short-term toxicity of the target substance to aquatic invertebrates is the EC50 (48 h) > 100 mg/L (nominal, OECD 202, D. magna, CAS 10023-48-0); read-across
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 - 19 Apr 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
2004
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)
Remarks:
Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany (18 Nov 2014)
Test material information:
Composition 1
Analytical monitoring:
yes
Remarks:
HPLC-UV
Details on sampling:
- Concentrations: Control and 100 mg/L
- Sampling method: Two replicates of each sample were taken directly after preparation of the test medium (0 h) and at the end of exposure (48 h). One replicate was used for analysis and the other was used as backup.
- Sample storage conditions before analysis: At ≤ - 20 °C. The stability of the test item during freezing was demonstrated in a separate non-GLP study.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution of 100 mg/L test item in Elendt M4 medium was prepared by stirring with a magnetic stirrer for 30 minutes.
- Controls: Elendt M4 medium (untreated test medium)
- Evidence of undissolved material: The test medium was a clear preparation and stayed unchanged throughout the study.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Water flea
- Source: Ibacon GmbH, Roßdorf, Germany
- Age of parental stock: max. 6 weeks old
- Age of daphnids at test start: < 24 h old
- Culture conditions: Daphnids are kept individually in 100 mL glass vessels containing approximately 60 mL Elendt M4 medium at a water temperature of 20 ± 2 °C and a 16 h light and 8 h dark regime to ensure similar conditions as in the experiment.
- Feeding during breeding: The parental daphnids are fed ad libitum with unicellular green algae (Pseudokirchneriella subcapitata) three times per week.
- Feeding during test: No

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
Parental daphnids are used for reproduction until they are about 6 weeks old. Thereafter, they are replaced by neonates.
Offspring are removed from the vessels at least twice per week.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
225 mg CaCO3/L (reconstituted water)
Test temperature:
19.6 - 20.0 °C
pH:
0 h: 7.82 (control), 7.03 (treatment)
48 h: 7.76 (control), 7.33 (treatment)
Dissolved oxygen:
0 h: 8.76 mg/L O2 (control), 8.70 mg/L O2 (treatment)
48 h: 8.44 ,g/L O2 (control), 8.37 mg/L O2 (treatment)
Conductivity:
652 µS/cm (reconstituted water)
Nominal and measured concentrations:
Control and 100 mg/L (nominal)
< LOD and 96.04 mg/L (0 h)/ 96.29 mg/L (48 h)
Details on test conditions:
TEST SYSTEM
- Test vessel: 20 mL glass test tubes containing at least 20 mL test medium.
- Type: Open vessels
- Aeration: No
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: 4 mL medium per daphnid

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (Elendt M4 medium) was prepared by dissolving medium components in fully demineralized water (Milli-Q Water Purification System).
- Conductivity: 652 µS/cm
- Culture medium different from test medium: Culture medium same as test medium
- Intervals of water quality measurement: At test start (0 h) and at test end (48 h)

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the test medium was not adjusted.
- Photoperiod: 16 h light and 8 h dark
- Light intensity: 779 lux (mean at 0 h) and 743 lux (mean at 48 h)

EFFECT PARAMETERS MEASURED:
- Mobility: after 24 and 48 h

RANGE-FINDING STUDY
- Results used to determine the conditions for the definitive study: Yes, in a static pre-test no immobilization was observed at a concentration of 100 mg/L under open static conditions. In a separate non-GLP study the stability of the test item in Elendt M4 for daphnids was confirmed over a period of 48 h in open vessels and after deep-freezing.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: No
- Mortality of control: 0%
- Any observations that might cause a difference between measured and nominal values: The test medium was a clear preparation and stayed unchanged throughout the study.
Results with reference substance (positive control):
- Results with reference substance valid? Yes, the result was within the published ranges of 0.6 - 1.7 mg/L (EC No. 440/2008) and 0.6 - 2.1 mg/L (OECD 202).
- Relevant effect levels: EC50 (48 h) = 0.82 mg/L
- Other: The last reference test dates from 13 - 15 Oct 2016.

VALIDITY CRITERIA

The test fulfilled the validity criteria of the guideline (Table 1).

 

Table 1: Validity criteria of OECD guideline 202.

Criterion from the guideline

Study results

Validity criterion fulfilled

In the control, including the control containing the solubilising agent, not more than 10% of the daphnids should have been immobilized.

No immobilization in the control group.

Yes

The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in control and test vessels.

The dissolved oxygen concentration at the end of the exposure period was ≥ 3 mg/L.

Yes

 

Validity criteria fulfilled:
yes
Remarks:
For further details please refer to “Any other information on results incl. tables”.

Description of key information

EC50 (48 h) > 100 mg/L (nominal, OECD 202, D. magna); read-across

Key value for chemical safety assessment

Additional information

There is no study available, in which the short-term toxicity of the target substance 2-[3-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazoniol-5-yl]ethyl dihydrogen diphosphate (CAS 136-09-4) to aquatic invertebrates was investigated. Therefore, read-across to the structurally and physico-chemically related source substance 2-{3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazol-3-ium-5-yl}ethyl hydrogen phosphate (CAS 10023-48-0) was conducted in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5. Based on the physico-chemical similarity, the source substance is considered a suitable proxy for the assessment of the short-term toxicity of the target substance to aquatic invertebrates. A detailed analogue approach justification is provided in IUCLID section 13 of the technical dossier.

In the available study, the short-term toxicity of the source substance (CAS 10023-48-0) to aquatic invertebrates was investigated according to OECD guideline 202 and GLP. In a static limit test, Daphnia magna was exposed to a limit concentration of 100 mg/L test item in open test vessels for 48 h. The test item concentration was analytically verified at test start (0 h) and at test end (48 h) by HPLC-UV.

The measured test item concentration was 96.04 mg/L after 0 h and 96.29 mg/L after 48 h, indicating that the substance was stable in Elendt M4 medium for the duration of the test. Since the actual test item concentration was within ± 20% of the nominal concentration, the effect concentration was based on the nominal concentration. After 48 h, no immobilization was observed at the nominal limit concentration of 100 mg/L and the reported EC50 (48 h) is > 100 mg/L.

Based on the high degree of structural and chemical similarity of the target and source substance, the target substance is expected to exhibit a similar ecotoxicological profile as the source substance. Therefore, it can be concluded that the target substance 2-[3-[(4-Amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazoniol-5-yl]ethyl dihydrogen diphosphate (CAS 136-09-4) does not cause short-term toxicity to aquatic invertebrates up to a nominal concentration of 100 mg/L.