4,4'-(2,3-epoxypropoxy)-2,2'- dimethyl-5,5'-tert-butyldiphenylsulphide

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:

18 April 2011 to 20 April 2011

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:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

2017

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Analytical measurements were performed at the controls and at the applied test concentration levels at the beginning and at the end of the test.
- The samples were analysed by an HPLC.

Vehicle:

no

Details on test solutions:

- Because the test material is very poorly soluble in water, in order to achieve the maximum solubility level of the test material (limit test concentration), a test solution was prepared using a saturated solution method. A saturated test material stock solution (100 mg/L nominal loading rate) was prepared by dispersing/dissolving the amount of test material into the test medium (ISO medium) two days before the start of the test. This solution was stirred for about 48 hours and then the non-dissolved test material was removed by filtration through a fine (pore size: 0.22 μm) filter to give the saturated solution.
- To demonstrate that every effort was made to achieve a detectable concentration, an additional test concentration above the solubility level of the test material was tested parallel with the limit test concentration. Organic solvent (acetone) was used during the formulation procedure. An amount of 250 mg test material was dissolved in 50 mL acetone thereafter 0.1 mL from this stock solution was diluted in 1000 mL of ISO medium to give the test concentration of 0.5 mg/L (nominal).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Justification for species: Daphnia magna is the standard species of the acute immobilisation test
- Source: Supplied by National Institute of Public Health. Cultured under standardised conditions at the testing laboratory
- Age: Daphnia magna were less than 24 h old at the beginning of the test
- Feeding during test: no

ACCLIMATION
- Acclimation period: There was no acclimatisation because the water used was similar to the culture water
- Before the test the Daphnia culture was fed with concentrated algal suspension of Pseudokirchneriella subcapitata

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

249 mg/L (as CaCO3)

Test temperature:

20.9 – 21.4°C

pH:

7.49 – 7.74

Dissolved oxygen:

6.7 – 7.1 mg/L

Nominal and measured concentrations:

Nominal: 100% saturated solution and 0.5 mg/L

The calculated geometric mean concentration of the test materual was 0.13 mg/L at 0.5 mg/L nominal concentration.

Details on test conditions:

TEST SYSTEM
- Test vessel: glass beakers
- Fill volume: at least 4 mL test solution/animal
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (ISO medium, according to OECD 202) was used as dilution water for both the range finding and definitive tests. The same composition of reconstituted water was used for the tests and for breeding the test animals.
Separate stock solutions of individual trace elements were first prepared in deionised water. The medium was prepared of these different stock solutions, so it contained all trace elements (combined solution): 25 mL of 11.76 g/L CaCl2.2H2O, 25 mL of 4.93 g/L MgSO4.7H2O, 25 mL of 0.23 g/L KCl and 25 mL 2.59 g/L NaHCO3.
- Intervals of water quality measurement: The water temperature was measured at the start of the test and 24-hour intervals thereafter in each test vessel. The dissolved oxygen concentration and pH was measured in each test vessel at the start and at the end of the test.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: The test was carried out in 16-hour light and 8-hour dark cycle.

EFFECT PARAMETERS MEASURED: The immobility or mortality of the Daphnia was determined by visual observation 24 and 48 hours after the start of the test. Those animals not able to swim within 15 seconds after gentle agitation of the test beaker were considered to be immobile. The number of immobilised animals and the percentage of immobility were determined at 24 and 48 hours.

RANGE-FINDING STUDY
- A concentration range-finding test was conducted to determine the approximate toxicity of the test material so that appropriate test concentrations can be selected for use in the definitive test. Ten daphnids (divided into two replicates) in each test concentration and control were exposed for 48 hours.
- Test concentrations: 0.125, 0.25 and 0.5 mg/L (nominal)
- Results used to determine the conditions for the definitive study: Yes, because toxicity was not observed during the preliminary concentration range-finding test, only one test concentration (at the solubility level of the test material in the test medium) and one control group were tested in a limit test.
Furthermore a test concentration (nominally 0.5 mg/L) using acetone as solvent and one additional control contained the solvent substance at the same concentration as that used in this test group (0.1 mL/L) were tested in parallel with the limit test concentration.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 0.13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 0.13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 0.13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 0.13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

VALIDITY
- There was a single (5%) immobilised animal in the control group and the dissolved oxygen concentration at the end of the test in control and test vessels was more than 3 mg/L. All validity criteria were within acceptable limits and therefore the study can be considered as valid.

CONCENTRATIONS OF THE TEST MATERIAL
- The test material was not detected in the control samples (neither normal nor solvent control).
- The concentration of test material was below the analytically detectable range in the 100% saturated solution.
- Measured concentration in the test group of 0.5 mg/L (nominal) was 0.36 mg/L at the start and below the Limit of Quantification (LOQ = 0.1 mg/L) at the end of the experiment. In order to calculate the mean exposure concentration at this concentration level, the end concentration was taken as the half of the Limit of Quantification. The calculated geometric mean concentration was 0.13 mg/L.
- Biological results are related to the geometric mean of the measured test material concentrations.

IMMOBILISATION
- There was 10% immobilisation in saturated solution after 24 and 48 hours of exposure. However, it was considered due to natural causes rather than toxic effects given that immobility was not observed in concentration of 0.5 mg/L (nominal) which represented a higher concentration than saturated. No other abnormal behaviour or appearance of test animals was detected.

Results with reference substance (positive control):

The 24h EC50: 1.61 mg/L, (95% confidence limits: 1.34 – 1.93 mg/L)

Reported statistics and error estimates:

- No statistical analysis was performed because of the lack of toxic effects.
- The EC50, NOEC, LOEC and EC100 values were determined directly from the raw data.

Table 1: Number and percentage of immobilised animals

Test Group	Number of Treated Animals	Number of Immobilised Animals
		24 Hours		48 Hours
		Number	Percent	Number	Percent
Control	20	0	0	1	5
Solvent Control	20	0	0	0	0
0.5 mg/L (nominal)	20	0	0	0	0
100 % saturated solution	20	2	10	2	10

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study no toxic effect was observed at both tested concentration levels. As the concentration of 0.5 mg/L (nominal) represented a higher level than the limit of solubility, it can be stated that the test material had no toxic effect at saturation (0.13 mg/L, measured).

Executive summary:

The acute toxicity of the test material to aquatic invertebrates was investigated in accordance with the standardised guidelines OECD 202, EU Method C.2 and OPPTS 850.1010, under GLP conditions.

Toxic effects were not observed during the preliminary concentration range-finding test therefore a limit test was performed in the main experiment using only one test concentration at the limit of solubility of the test material in the test medium (100% saturated solution) and one control group.

The measured concentrations were below the analytically detectable range in the case of 100% saturated solution. Furthermore a test concentration of 0.5 mg/L nominally (in the analytically measurable range) using acetone as solvent and one additional control contained the solvent substance at the same concentration (0.1 mL/L) as that used in the test group were tested in parallel. The corresponding calculated concentration of this test group (based on the analytical measurements) was 0.13 mg/L. As the measured concentration deviated more than 20 percent from the nominal concentration during the test, the results are based on the measured geometric mean test material concentration.

During the definitive study, twenty Daphnia magna, divided into four groups (glass beaker) of five animals each were used for each test group. The daphnia were observed over an exposure period of 48 hours in a static test system.

All validity criteria were met during this study.

The observed endpoints for the test material were: 24 and 48 h EC50 value > 0.13 mg/L (measured), 48 h NOEC = 0.13 mg/L (measured), 48 h LOEC > 0.13 mg/L (measured) and 48 h EC100 value > 0.13 mg/L (measured).

Under the conditions of this study no toxic effect was observed at both tested concentration levels. As the concentration of 0.5 mg/L (nominal) represented a higher level than the limit of solubility, it can be stated that the test material had no toxic effect at saturation (0.13 mg/L, measured).

Description of key information

Under the conditions of this study no toxic effect was observed at both tested concentration levels. As the concentration of 0.5 mg/L (nominal) represented a higher level than the limit of solubility, it can be stated that the test material had no toxic effect at saturation (0.13 mg/L, measured).

Additional information

The acute toxicity of the test material to aquatic invertebrates was investigated in accordance with the standardised guidelines OECD 202, EU Method C.2 and OPPTS 850.1010, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Toxic effects were not observed during the preliminary concentration range-finding test therefore a limit test was performed in the main experiment using only one test concentration at the limit of solubility of the test material in the test medium (100% saturated solution) and one control group.

The measured concentrations were below the analytically detectable range in the case of 100% saturated solution. Furthermore a test concentration of 0.5 mg/L nominally (in the analytically measurable range) using acetone as solvent and one additional control contained the solvent substance at the same concentration (0.1 mL/L) as that used in the test group were tested in parallel. The corresponding calculated concentration of this test group (based on the analytical measurements) was 0.13 mg/L. As the measured concentration deviated more than 20 percent from the nominal concentration during the test, the results are based on the measured geometric mean test material concentration.

During the definitive study, twenty Daphnia magna, divided into four groups (glass beaker) of five animals each were used for each test group. The daphnia were observed over an exposure period of 48 hours in a static test system.

All validity criteria were met during this study.

The observed endpoints for the test material were: 24 and 48 h EC50 value > 0.13 mg/L (measured), 48 h NOEC = 0.13 mg/L (measured), 48 h LOEC > 0.13 mg/L (measured) and 48 h EC100 value > 0.13 mg/L (measured).

Under the conditions of this study no toxic effect was observed at both tested concentration levels. As the concentration of 0.5 mg/L (nominal) represented a higher level than the limit of solubility, it can be stated that the test material had no toxic effect at saturation (0.13 mg/L, measured).