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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
04 July 2017 - 06 July 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The analysis was carried out by measuring the concentration of Copper using a suitable ICP method.
Duplicate samples were taken from each replicate at the beginning and at the end of the renewal periods at the applied test concentration levels as well as from the control. Samples were taken in plastic tubes, acidified with pure nitric acid (9 mL sample + 1 mL HNO3) in agreement with the requirements of the Principal
Investigator. To avoid any problems with microparticles, therefore the samples were membrane filtrated before acidification.
After sampling, one set of the samples was stored under test conditions and then sent to the Test Site for analysis. One set of the samples is retained as a back-up at the Test Facility, thus these samples were frozen and kept approximately at -20°C at the Test Facility, if required for any confirmatory analyses
Vehicle:
no
Details on test solutions:
The test item was a multi constituent substance and poorly soluble in water, test solutions were prepared using a saturated solution method (water accommodated fraction, WAF) according to the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, OECD No. 23.
Saturated test item solutions based on nominal loading rates of 0.125, 0.25, 0.5, 1.0 , 2.0, 4.0 and 8.0 mg/L (WAFs)] were prepared individually by dispersing/dissolving the amount of test item into the test medium (ISO Medium) two days before the start of the test. These solutions were shaken for about 24 hours at approximately 30°C and then equilibrated for about 24 hours at approximately 20°C. The non-dissolved test material was removed by filtration through a fine (0.22 μm) filter to give appropriate nominal loading rates.
As the lowest concentration cannot be prepared individually with a sufficient precision, therefore it was prepared from a serial dilution of the next concentration level (0.125 mg/L WAF) to give the 50 % saturated solution of 0.125 mg/L nominal loading rate WAF (200.0 mL 0.125 mg/L WAF solution was diluted with ISO Medium up to 400 mL).
Test solutions were prepared just before introduction of the Daphnia (start of treatments).
In absence of stability data the test was performed under semi-static conditions. The frequency of the water renewal periods was 24 hours. Prior to the treatment of the renewal periods the test item solutions were prepared by the method described above.

A vehicle control group consisting of untreated dilution water was also assessed.
Test organisms (species):
Daphnia magna
Details on test organisms:
Daphnia magna
Justification of strain: Daphnia magna is the standard species of the acute immobilisation test.
They were less than 24 h old at the beginning of the test.
There were 20 animals in test group and control group respectively, divided into 4 replicates (5 animals / replicate)

There was no acclimatization because the water used was similar to the culture water.

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
248 mg/L (as CaCO3)
Test temperature:
20.4 – 20.8°C
pH:
7.43 – 7.76
Dissolved oxygen:
7.0 – 8.6 mg/L.
Salinity:
-
Conductivity:
-
Nominal and measured concentrations:
WAF, Nominal loading rates = 0.125, 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 mg/L. A test group at 50% of the concentration of the 0.125 mg/L loading level was also tested.
Measured concentrations were below the limit of qauanitiation (0.15 mg/L) for all test groups at each timepoint.
Details on test conditions:
The test duration was 48 hours. Twenty animals, divided into four groups (glass beaker) of five animals each (at least 5 mL test solution/animal) were used at the test concentration and for the control group as well.
In absence of stability data the test was performed under semi-static conditions. The frequency of the water renewal periods was 24 hours. The animals were not fed during the test.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
48 h
Dose descriptor:
EL50
Effect conc.:
1.99 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (total fraction)
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOELR
Effect conc.:
1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The 24h EL50 value: 4.68 mg/L nominal loading rate WAF (95 % conf. limits: 3.61 – 6.56 mg/L nominal loading rate WAF)
The 48h EL50 value: 1.99 mg/L nominal loading rate WAF (95 % conf. limits: 1.69 – 2.35 mg/L nominal loading rate WAF)
The 48h EL100 value: 4.0 mg/L nominal loading rate WAF
The 48h No-Observed Effect Loading Rate (NOELR): 1.0 mg/L nominal loading rate WAF
The 48h Lowest Observed Effect Loading Rate (LOELR): 2.0 mg/L nominal loading rate WAF
Results with reference substance (positive control):
The 24h EC50: 0.64 mg/L, (95 % confidence limits: 0.59 – 0.68 mg/L)
Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of this Daphnia magna acute immobilisation study the observed endpoints for the effect of B331 was the following:
The 24h EL50 value: 4.68 mg/L nominal loading rate WAF (95 % conf. limits: 3.61 – 6.56 mg/L nominal loading rate WAF)
The 48h EL50 value: 1.99 mg/L nominal loading rate WAF (95 % conf. limits: 1.69 – 2.35 mg/L nominal loading rate WAF)
The 48h EL100 value: 4.0 mg/L nominal loading rate WAF
The 48h No-Observed Effect Loading Rate (NOELR): 1.0 mg/L nominal loading rate WAF
The 48h Lowest Observed Effect Loading Rate (LOELR): 2.0 mg/L nominal loading rate WAF

Description of key information

Daphnia magna, 48 hours: EL50 = 1.99 mg/L; NOELR = 1.0 mg/L

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
1.99 mg/L

Additional information

An acute daphnia immobilisation study was conducted (CiToxLAB Hungary, 2017) to assess the short-term effects of B331 on aquatic invertebrates. The study was conducted according to OECD test guideline 202 and EC method C2, and in compliance with GLP. The test media was prepared as a water accomodated fraction (WAF) with nominal loading rates of (50% saturated solution at 0.125 mg/L loading), 0.125, 0.25, 0.5, 1.0, 2.0, 4.0 and 8.0 mg/L; a concurrent vehicle control group (untreated dilution water) was used. Test media were replaced every 24 hours.

Analysis of the test solutions in all dose levels at each sampling timepoint revealed the test material concentration to be below the limit of quantitation of 0.15 mg/L (measured for copper concent by ICP-AES; LoQ = 0.013 mg Cu/L).

Daphnia were found immobilised in the 2.0, 4.0 and 8.0 mg/L loading rate levels at 24 and 48 hours. The 48 hour EL50 was 1.99 mg/L. The 48 hour NOELR was 1.0 mg/L.