Phosphoric acid, butyl ester, sodium salt

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:

weight of evidence

Study period:

from 2007-02-22 to 2007-05-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))

Deviations:

no

GLP compliance:

no

Remarks:

The study was conducted in accordance with ISO/IEC 17025.

Specific details on test material used for the study:

Batch number: CHA0029466
Active ingredient (a.i.) content, nominal: 100%

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Prior to the test, a batch of reconstituted water was aerated vigorously over a period of 2 h. Final test concentrations were prepared with this aerated water by dilution of stock solutions of the test substance. 2 h before the test, vessels were filled with the formulated media to allow equilibration of pH, oxygen and temperature.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: Straus, 1820
- Source: in-house culture
- Age of parental stock: Parental and young Daphnia
- Feeding during test: no feeding

ACCLIMATION
- Acclimation period: Daphnia, which had been selected in size, were acclimatized to the reconstituted water for 4 hours before introduction into the test media.
- Acclimation conditions: same as test
- Type and amount of food: 15 g sera micropan (sera GmbH, D-52525 Heinsberg) homogenized in 1 L deionised water

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20 ± 0.5 °C

pH:

7.2 - 7.7

Dissolved oxygen:

6.3 - 6.4 mg/L

Salinity:

NA

Conductivity:

<1.5 µS/cm

Nominal and measured concentrations:

Nominal concentrations: 1, 10 and 100 mg/L
No measured concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: flasks
- Material, size, headspace, fill volume: 100 mL flasks, all-glass, with 50 mL of test medium
- Aeration: no aeration
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (lSO 6341) prepared with distilled water (conductivity <1.5 µS/cm). The final test medium contained 25 mL/L of each of the following four stock solutions: CaCl2 x 2H2O, 11.76 g/L; MgSO4 x7H2O,4.93 g/L; NaHCO3, 2.59 g/L; KCl, 0.23 g/L. The sum of the Ca and Mg ions in this solution is 2.5 mmol/L.
- Alkalinity: 0.8 mmol/L
- Ca/mg ratio: 4:1
- Na/K ratio: 10:1

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h photoperiod a day
- Light intensity: overhead white fluorescent tubes

Reference substance (positive control):

yes

Remarks:

Periodically conducted reference test with potassium dichromate.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

At all nominal test concentrations no significant effects (<10 % immobilization) were observed after 24 and 48 h of exposure. No significant effects were also observed in the control atler 24 and 48 h of exposure.

Results with reference substance (positive control):

Not reported.

Table 1: lmmobilisation of Daphnia magna after 24 and 48 h of exposure to the test material

Nominal concentration (mg/L)	Code	Number of individuals per test vessel	Immobile Daphnia (No./vessel) 24 h	Immobile Daphnia (No./vessel) 48 h	% immobile Daphnia after 24 h of exposure	% immobile Daphnia after 48 h of exposure
Control 0	A B C	20 20 20	0 0 0	0 0 0	0 0 0	0 0 0
1	A B	20 20	0 0	0 0	0 0	0 0
10	A B	20 20	0 0	0 1	0 0	0 5
100	A B	20 20	0 0	0 0	0 0	0 0

Validity criteria fulfilled:

yes

Conclusions:

No significant effects were observed in the control and the test concentrations. Therefore, the EC50 was determined to be >100 mg/L.

Executive summary:

In the acute immobilisation test with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD 202, Regulation (EC) No. 440/2008 Method C.2 and ISO 6341. The study was conducted in a static system over a period of 48 hours with test concentration of 1, 10 and 100 mg/L. 40 daphnids per test concentration in two replicates and control in three replicates were tested. The test item concentration was not determined, thus, all biological endpoints were based on the nominal concentration. There was no immobilisation observed in twenty daphnids exposed to each test item treated and control group. Further no abnormal behaviour or appearance of test animals was noted. The estimated EC50 value (48 hours) of the test item based on the nominal concentration is >100 mg/L.

Description of key information

No significant effects were observed in the control and the test concentrations for both the target and the source substances. Therefore, the EC50 was determined to be >100 mg/L.

Additional information

In the acute immobilisation test with Daphnia magna (STRAUS), the effects of the test item were determined according to OECD 202, Regulation (EC) No. 440/2008 Method C.2 and ISO 6341. The study was conducted in a static system over a period of 48 hours with test concentration of 1, 10 and 100 mg/L. 40 daphnids per test concentration in two replicates and control in three replicates were tested. The test item concentration was not determined, thus, all biological endpoints were based on the nominal concentration. There was no immobilisation observed in twenty daphnids exposed to each test item treated and control group. Further no abnormal behaviour or appearance of test animals was noted. The estimated EC50 value (48 hours) of the test item based on the nominal concentration is >100 mg/L.

Additionally, a read-across to Dibutyl hydrogen phosphate (CAS 107-66-4) was performed in a weight of evidence approach. A study was performed according to OECD 202 and Council Regulation (EC) No 440/2008, Method C.2 ‘Acute toxicity for Daphnia’ (2008) to assess the acute toxicity of the source item to Daphnia magna STRAUS under semi-static conditions. A range finding test preceded the main test. The following nominal concentrations of the source item were tested in the range finding test: 1, 3.2, 10, 32 and 100 mg/L. In the main test, Daphnia were exposed to the source item added to dilution water at a limit test concentration of nominally 100 mg/L for a period of 48 hours. The main test was conducted as a semi-static test with daily renewal of test medium. During the test a temperature range of 18 - 22 °C was maintained in the test vessels, with a maximum temperature fluctuation of ± 1 °C in each individual test. The temperature, the pH and the oxygen values were measured every day in the freshly prepared media and in the media after 24 hours of exposure. Immobilisation rates and any abnormal behaviour were recorded at 24-hour intervals. Analytically determined values of the test concentration varied not more than 6.2 %, therefore, the EC50 is given as nominal concentration. At the limit concentration no toxic effects against Daphnia were observed at the end of the 48 hour study period. After 48 hours of exposure an EC50 of >100 mg/L (nominal) for the source substance was determined.

Both the target and the source substance showed no effects on Daphnia magna after 48 hour exposure at a limit test concentration of 100 mg/L. The EC50 for both substances was determined to be >100 mg/L. In conclusion, the target substance is not significantly toxic to Daphnia magna up to a concentration of 100 mg/L.