Phosphorous acid, tri-C12-14-alkyl esters

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

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)

Deviations:

yes

Remarks:

there were minor deviations not affecting the validity of the study

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

DETAILS ON PREPARATION
As the solubility of the test item in the test medium was below 100 mg/L and according to the available information, stability was not given over a period of more than 24 hours, the test solutions were prepared as follows. The load of 781 mg/L (corresponding to a volume of 0.884 mL/L based on a density of 0.883 g/mL) was added to the corresponding amount of dilution water and homogenised for 30 minutes at 30°C in an ultrasonic bath. Afterwards, the solution was stirred for 30 minutes on a magnetic stirrer. Then, the solution was homogenised again using ultrasonic for 15 min and afterwards stirred for 15 minutes. The resulting clouded solution was filtrated through 0.45 µm nylon filters. An aliquot was examined for colloidal particles by testing the solution with a laser for the Tyndall effect. This solution was stated as the 100 % saturated solution. Each day of the test, a new test solution was freshly prepared.

Test organisms (species):

Daphnia magna

Details on test organisms:

Species Daphnia magna
Variety STRAUS
Strain Berlin
Sex female
Age between 0 and 24 hours
Origin Umweltbundesamt Berlin
Arrival of Strain 27. Sep. 2007
Vessels preserving glasses, nominal volume 2 l
Medium M4-Medium (recipe of ELENDT)
Food unicellular green algae (Desmodesmus subspicatus)
Medium renewal twice a week
Photo period 16/8 hours, using neon tubes
Temperature 20 ± 2 °C

The husbandry is performed similar to the method described in EN ISO 6341, following SOP 115 002 01 (“Zucht und Hälterung von Daphnia magna STRAUS“), edition 11, adopted 15. Jan. 2013.

20 hours before the start of the test, the adult animals were separated from the young. 19 hours later, the adults were caught with the help of a glass tube, and the newborn daphnia, aged between 0 and 20 hours, were sieved from the medium and immediately placed into a 250 mL-beaker containing dilution water. After a settling-in period of 30 minutes, animals which showed no apparent damage were used for the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

2.502 mmol CaCO3/L i.e 250 mg CaCO3/L

Test temperature:

20.8 – 22.7 °C

pH:

7.6 - 7.7

Dissolved oxygen:

> 8.2 mg O2/L

Nominal and measured concentrations:

Nominal : 781 mg/L
Limit of solubility = approx. 5.4 mg/L, based on the geometric mean of the measured DOC concentrations in the fresh prepared solutions

Details on test conditions:

The following experimental conditions apply to all studies.
Test vessels glass beakers, nominal volume 50 mL, tall shape
Feeding none
Lighting none
Date of performance 01. – 03. Mar. 2013
Treatment 781 mg/L
Temperature 20.8 – 22.7 °C
Duration 48 hours
Observation times 24 and 48 hours
Replicates four vessels, each containing 20 ± 5 mL test solution and five daphnia
Control four vessels, each containing 20 ± 5 mL dilution water and five daphnia

Using a glass tube (diameter approx. 8 mm), the daphnia were caught and lifted from the beaker. They were put on a small sieve, and the medium surrounding the animals was sucked off using absorbent paper. Immediately after that, the animals were put into the respective test solution. Due to a writing error in the study plan, the test concentration was 781mg/L instead of 100 mg/L. As both concentrations are far above the limit of solubility of the test item and the saturated solution was tested, this deviation was stated as uncritical.
The test vessels were left to stand for 24 hours. Then, the vessels were inspected for immobilised daphnia, and medium renewal was performed: the daphnia were put into new test vessels with freshly prepared test solution. After 48 hours, the immobilised daphnia were counted again. Daphnia are considered immobilised if they perform no movements or are only able to move their antennae when the beaker is gently agitated.
The pH, the concentration of dissolved oxygen and the content of the test item in the test vessels were measured at the beginning and at the end of the test and at every medium renewal in the old and the new test solution.
The variation of temperature during the test was in a range of 20.8 to 22.7 °C and therefore higher than demanded in the study plan. As no significant immobility occurred in the test, this deviation was stated as uncritical.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9)

Duration:

24 h

Dose descriptor:

NOELR

Effect conc.:

>= 781 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

>= 781 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

24 h

Dose descriptor:

LL50

Effect conc.:

> 781 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

LL50

Effect conc.:

> 781 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

In the control and one replicate of the treatment, immobilities were recorded. As the percentage of immobilisation was not significant and did not exceeds 10% at the end of the test, a full study did not have to be conducted.
None of the surviving daphnia showed any signs of abnormal behaviour throughout the test.

Results with reference substance (positive control):

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study (201207R201). The value was determined as 1.5 mg/L, lying within the demanded range of 0.6 – 1.7 mg/L.

The immobilities were recorded daily and can be found in the following table:

Nominal Concentration in mg/L	Immobility 24 hours					Immobility 48 hours
	abs.				in %	abs.				in %
0	0	0	0	0	0	0	0	0	1	5
781	0	0	0	0	0	0	0	0	2	10

Validity criteria fulfilled:

yes

Remarks:

The 24h-EC50i of K2Cr2O7 was determined as 1.5 mg/L in a separate GLP study. Immobilisation in the controls did not exceed 10 %. The lowest concentration of dissolved oxygen at the end of the test was 8.2 mg/L. The pH highest variation was 0.1 units

Conclusions:

48h NOELR ≥ limit of solubility (approx. 3.5 mg/L in the test media) with a loading rate of 781 mg/L
48h LL50 > limit of solubility (approx. 3.5 mg/L in the test media) with a loading rate of 781 mg/L

Executive summary:

As the solubility of the test item in the test medium was below 100 mg/L and stability was not given over a period of more than 24 hours, the fish toxicity test was performed in semi-static conditions. A load of 795 mg/L was added to the corresponding amount of dilution water (drinking water) and homogenised. This solution was stated as a 100 % saturated solution.

The study was performed as a limit test at the nominal concentration containing 781 mg/L resp. 100% saturation. Twenty daphnia were exposed to the test item for 48 hours in a semi-static test system.

The tested concentration showed no significant toxicity.

48h NOELR≥limit of solubility (approx. 3.5 mg/L in the test media)

48h LL50 > limit of solubility (approx. 3.5 mg/L in the test media)

Description of key information

The toxicity of the test item to the Daphnia mnagna was investigated in a GLP-compliant study performed in accordance with OECD Guideline No. 202.

The 48h NOELR ≥ limit of solubility (approx. 3.5 mg/L in the test media) with a loading rate of 781 mg/L (100% staurated solution)

The 48h LL50 > limit of solubility (approx. 3.5 mg/L in the test media) with a loading rate of 781 mg/L (100% staurated solution)

Additional information

The toxicity of the test item to freshwater flea Daphnia magna was investigated in one GLP-compliant study performed in accordance with standard methods, with minor deviations. The study is considered as reliable (Klimisch 1) and is selected as a key study for the endpoint.