Chromium tris((2-ethylhexanoate)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

4 April 2017 - 21 June 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April 2004

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

not specified

Details on sampling:

Range-finder test:
The test soluitions were prepared in ISO medium by water accomodated fractions (WAF) at 3 loading rates equivalent to: 100, 1000 and 10 000 mg test item/L. A control was set up with ISO test medium only. There were 4 replicates for each treatement and for the control. 5 daphnids were introduced in each replicates (each one contianing 50 mL of test solution.
Organisms were maintained at temperature of 20°C +/- 2°C and light intensity under 300 lux with a light: dark cycle of 16 hours light and 8 hours dark.
After 24 and 48 hours, the number of immobile daphnids in each replicate were recorded. pH and dissolved oxygen were recorded at the beginning and the end of the test.

Definitive test:
Besed on the results of the range-finde, concentrations were prepared in ISO medium by water accomodated fractions (WAF) at 5 loading rates equivalent to6.25; 12.5; 25; 50 and 100 mg test item/L. A control was set up with ISO test medium only. There were 4 replicates for each treatment and for the control. 5 daphnids were introduced in each replicate (each one containing 50 mL of test solution).
Organisms were maintained at temperature of 20°C +/- 2°C and light intensity under 300 lux with a light: dark cycle of 16 hours light and 8 hours dark.
After 24 and 48 hours, the number of immobile daphnids in each replicate were recorded. pH and dissolved oxygen were recorded at the beginning and the end of the test.

Test solution analysis:
The test item quantification was performed according to a validated analytical method to measure the concentration of the test item at the start and the end of the test.
Test item solution and control were sampled (approximately 50 mL) and transferred to analyse the same day.

Vehicle:

no

Details on test solutions:

Since test item is a poorly soluble substance under test condition, test solutions were prepared by accomodated fractions (WAF) approach according to OECD monograph n° 23. WAFs were prepared individually. Measured quantities of test item were added directly to test medium and mixed for 48 hours to achieve an equilibrated concentration of dissolved and dispersed or emulsified components in the aqueous phase. Following cessation of mixing and a period of settling (to allow phase separation), the aqueous phase was drawn off for testing.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna Straus clone 5, between 6 and 24 hours old and produced from parthenogenical reproducing female population were used. Daphnia are issued from the breeding lab. The selection of the juvenile was daily realized by filtration. The juvenile stemming at least from the second litter were used to start the test.

Test type:

static

Water media type:

other: reconstituted test water

Remarks:

Elendt M4

Limit test:

no

Total exposure duration:

48 h

Hardness:

140-250 mg/L CaCO3

Test temperature:

20.0 +/- 2 degrees Celsius

pH:

Range-finder test: pH at the beginning of the test = 7.29
Definitive test: pH at the beginning of the test = 7.42

Nominal and measured concentrations:

nominal concentrations: 0, 6.25, 12.5, 50 and 100 mg test item/L

Details on test conditions:

Daily feeding: Pseudokirchneriella subcapitata and Chlorella vulgaris suspensions, spirulin.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

58.612 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: [55.361 - 61.862]

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

62.561 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: [58.487 - 66.634]

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

47.37 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: [44.744 - 49.997]

Duration:

24 h

Dose descriptor:

EC10

Effect conc.:

51.947 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: [48.565 - 55.328]

Details on results:

No other biological effects observed.

Results with reference substance (positive control):

The toxic response obtained on the reference item Potassium dichromate (April 4, 2017) gives an EC50-24h of 0.999 mg/L (0.932 – 1.067), indicating that the daphnids sensitivity is correct (within the accepted interval of 0.6 – 2.1 mg/L.

Reported statistics and error estimates:

The probits method was used for the estimation of EC10 and EC50.

Daphnids immobilisation:

Nominal test item concentration in mg/L	Number of daphnids exposed at the start	Immobilised daphnids (%) at 24h	Immobilised daphnids (%) at 48h
Control	20	0 (0%)	0 (0%)
6.25	20	1 (5%)	1 (5%)
12.5	20	0 (0%)	0 (0%)
25	20	0 (0%)	0 (0%)
50	20	1 (5%)	2 (10%)
100	20	20 (100%)	20 (100%)

Validity criteria fulfilled:

yes

Conclusions:

Based on the number of immobilized daphnids, the EC50 of the test item after a 24-hour exposure period was calculated to be 62,561 mg.L-1 (58,487 – 66,634 mg.L-1 95% confidence limits), and the EC50 after a 48-hour exposure period was calculated to be 58,612 mg.L-1 (55,361 – 61,862 mg.L-1 95% confidence limits).

Description of key information

In the experimental conditions of an OECD 202 test, the EC50 of the test item after a 24-hour exposure period was calculated to be 62,561 mg.L-1 (58,487 – 66,634 mg.L-1 95% confidence limits), and the EC50 after a 48-hour exposure period was calculated to be 58,612 mg.L-1 (55,361 – 61,862 mg.L-1 95% confidence limits).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

58.612 mg/L