Sodium 2-[methyl(1-oxododecyl)amino]ethanesulphonate

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:

2012-11-20 to 2012-11-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Read-Across Study

Justification for type of information:

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. See section 13 for the full read-across justification.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 1.25 - 2.50 - 5.00 - 10.0 - 20.0 - 40.0 mg/L (dilution factor 2).
- Sampling method: All test concentrations and the control were analytically verified by LC-MS/MS in the fresh (at 0 h) and old media (after 48 h) as specified below.
Sampling from freshly prepared media was carried out immediately before application.
Samples of the old media were taken directly from the test vessels, which contained the daphnids.
- Sample storage conditions before analysis:All original samples were stored room temperature until sample preparation. Prepared samples were stored at room temperature until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution (40.0 mg/L of the test item were weighed out) was freshly prepared with dilution water. Dispersion treatment was agitation
- Eluate: Dilution water
- Differential loading: 1.25 - 2.50 - 5.00 - 10.0 - 20.0 - 40.0 mg/L (dilution factor 2).
- Controls: Dilution water without test item tested under the same conditions as the test groups.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (STRAUS)
- Strain: Clone 5
- Source: Institut für Wasser-, Boden- Lufthygiene (WaBoLu), further own breeding
- Age at study initiation (mean and range, SD): 2 to 24 h
- Method of breeding: In 2-3 L glass vessels with appr. 1.8 L culture medium, at 20 +/- 2 °C, in an incubator, 16 h illumination, illumination strength max. 20 µExm-2 x s-1
- Feeding during test: No feeding

ACCLIMATION
- Acclimation period: 2 h
- Acclimation conditions (same as test or not): Same as test
- Type and amount of food: No feeding
- Health during acclimation (any mortality observed): Healthy, no mortality observed

DILUTION WATER:
Dilution water ISO test water, according to OECD 202, Annex 3:
Component Concentration [mg/L]
KCl 5.76
NaHCO3 64.8
CaCl2  2 H2O 294
MgSO4  7 H2O 123
pH-value: 7.8  0.2

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

No

Hardness:

Dilution water at test start: 256 (mg CaCO3/L)

Test temperature:

20.1 °C (Water)

pH:

Water Quality Parameters at 0 h (Fresh Media)
(measured in one additional replicate per concentration level and control)
Nominal concentration
of the test item
[mg/L] pH-Value


40.0 7.78
20.0 7.83
10.0 7.82
5.00 7.85
2.50 7.86
1.25 7.91
Control 7.89

Water Quality Parameters after 48 h (Old Media)
(measured in all replicates)
Nominal concentration
of the test item
[mg/L] pH-Values
Replicates
1 2 3 4
40.0 7.61 7.64 7.64 7.65
20.0 7.66 7.65 7.63 7.61
10.0 7.69 7.67 7.67 7.67
5.00 7.75 7.71 7.70 7.69
2.50 7.77 7.77 7.76 7.76
1.25 7.77 7.76 7.76 7.75
Control 7.69 7.68 7.68 7.71

Dissolved oxygen:

Water Quality Parameters at 0 h (Fresh Media)
(measured in one additional replicate per concentration level and control)
Nominal concentration
of the test item
[mg/L] Dissolved O2-Concentration

[mg/L]
40.0 8.65
20.0 8.66
10.0 8.69
5.00 8.68
2.50 8.69
1.25 8.72
Control 8.74

Water Quality Parameters after 48 h (Old Media)
(measured in all replicates)
Nominal concentration
of the test item
[mg/L] Dissolved O2 -Concentration [mg/L]
Replicates
1 2 3 4
40.0 7.10 7.23 7.23 7.08
20.0 7.19 6.85 6.71 6.97
10.0 7.11 7.48 7.54 7.54
5.00 7.61 7.54 7.75 7.52
2.50 8.30 8.29 8.36 8.42
1.25 8.28 8.41 8.37 8.44
Control 8.30 8.01 8.02 8.21

Salinity:

Not measured, freshwater

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers, 50 mL
- Type (delete if not applicable): closed with parafilm
- Material, size, headspace, fill volume: Glass beakers (4 cm ID x 7 cm H), 50 mL
- Aeration: No
- Renewal rate of test solution (frequency/flow rate): static test
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): None


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: see above
- Conductivity: Dilution water at test start:632 µS/cm
- Culture medium different from test medium: Elendt M4 acc. to ELENDT (1990), modified to a total hardness of 160 to 180 mg CaCO3/L
- Intervals of water quality measurement: At test start and test end


OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16:8 light:dark cycle
- Light intensity: Diffuse light, illumination strength max. 20 µE x m-2 x s-1


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Immobility was determined in all groups after 24 h and 48 h.

TEST CONCENTRATIONS
- Range finding study:
Immobilization Rates in the non GLP Preliminary Range Finding Test
(n = 20, divided into 2 replicates with 10 daphnids each)
Nominal
Test Item
Concentration
[mg/L] IMMOBILIZATION [%]
24 h 48 h
Replicates Replicates
1 2 MV 1 2 MV
10 50 0 25 80 30 55
1 0 0 0 0 0 0
0.1 0 0 0 0 0 0
Control 0 0 0 0 0 0

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

7.46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

is UVCB means 100% act.ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% CI 6.3-8.9 mg/L

Details on results:

- Mortality of control: 0 %
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50/LC50: 1.73 (CI 1.67 - 1.79) mg/L

Reported statistics and error estimates:

EC10- and EC50-values were calculated by sigmoidal dose-response regression. The confidence intervals were calculated from the best-fit values, the standard error and the
t-distribution with the software GraphPad prism5. The concentration effect relationships are presented graphically.

Immobilization Rates in the Definitive Test after 24 and 48 h of Exposure

                 (n = 20, divided into 4 replicates with 5 daphnids each)

Nominal		IMMOBILIZATION [%]
test item concentration [mg/L]	active ingredient [mg a.i./L]	24 h					48 h
		Replicates					Replicates
		1	2	3	4	MV	1	2	3	4	MV
40.0	28.9	100	100	100	80	95	100	100	100	100	100
20.0	15.5	20	80	80	100	70	80	100	100	100	95
10.0	7.23	40	20	20	40	30	60	80	80	40	65
5.00	3.62	20	20	0	40	20	40	40	0	40	30
2.50	1.81	0	0	0	0	0	0	0	0	0	0
1.25	0.904	0	0	0	0	0	0	0	0	0	0
Control		0	0	0	0	0	0	0	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

Based on the nominal concentrations of the source substance SMCT, the 48-h EC50 for Daphnia magna was estimated to be 7.46 mg/L (95 % confidence limits: 6.27 – 8.88 mg/L). This corresponds to 5.39 mg a.i./L (95 % confidence limits: 4.53 – 6.42 mg a.i./L) based on the nominal active ingredient.

The NOEC after 48 h was 2.50 mg/L, which corresponds to 1.81 mg a.i./L. The LOEC after 48 h was 5.00 mg/L, which corresponds to 3.62 mg a.i./L.

Based on read-across, this acute daphnia toxicity result is applied to the registration (target) substance SMLT. This is a conservative read-across since the available data on other alkyl taurate amide salts indicates toxicity increases with increasing chain length, and SMCT contains constituents with chain lengths in the range C12-C18 whilst SMLT is essentially 'pure' C12.

Executive summary:

In the acute immobilization test with Daphnia magna (STRAUS), the effects of the read-across source substance Sodium methyl cocoyl taurate (SMCT; batch number: DEB4003323) were determined according to OECD 202 (2004) from 2012-11-20 to 2012-11-22 at Dr.U.Noack-Laboratorien, Käthe-Paulus-Str.1, 31157 Sarstedt, Germany.

The study was conducted under static conditions over a period of 48 h with 6concentration levels of the test item Sodium methyl cocoyl tauratein the range of 1.25 to 40.0 mg/L, prepared with dilution water in a geometric series with a factor of 2. This corresponds to the nominal concentrations of the active ingredient in the range of 0.904 to 28.9 mg a.i./L. Twenty daphnids were exposed to each concentration level and the control.

The concentrations of the test item Sodium methyl cocoyl tauratewere analytically verified by LC-MS/MS in the fresh media (0 h) and in the old media (48 h) of all concentration levels and the control.

The measured concentrations of the test item in the fresh media (0 h) were in the range of 97 to 108 % of the nominal values. The recoveries of the test item in the old media (48 h) were in the range of 102 to 109 % of the nominal values, indicating that the concentrations of the test item were successfully maintained for the duration of the test. The endpoints were assessed based on the nominal concentrations of the test item Sodium methyl cocoyl taurateand additionally given based on the nominal concentrations of the active ingredient (Table 1).

The water quality parameters (i.e. pH-values and dissolved oxygen concentrations), measured at 0 and 48 h, were within the acceptable limits. The validity criteria of the test guideline were fulfilled.

IMPORTANT NOTE TO AVOID CONFUSION:

As the registration substance is a UVCB this means that the test item is 100% active ingredient.

EC₁₀-, EC₅₀- (with Confidence Interval), EC₁₀₀-Values (based on the nominal concentrations of the test item)

Endpoints	Test duration [h]	Sodium methyl cocoyl taurate
		Nominal concentrations of the test item [mg/L]
EC10 (with 95 % confidence limits)	24	4.16 (1.25 – 7.26)
	48	3.24 (2.15 – 4.37)
EC50 (with 95 % confidence limits)	24	14.0 (10.5 – 19.4)
	48	7.46 (6.27 – 8.88)
EC100	24	> 40.0
	48	40.0
NOEC	48	2.50
LOEC	48	5.00

Based on read-across, this acute daphnia toxicity result is applied to the registration (target) substance SMLT. This is a conservative read-across since the available data on other alkyl taurate amide salts indicates toxicity increases with increasing chain length, and SMCT contains constituents with chain lengths in the range C12-C18 whilst SMLT is essentially 'pure' C12. See attached read-across justification in section 13 for additional details

Description of key information

Based on the nominal concentrations of the source substance SMCT, the 48-h EC50 for Daphnia magna was estimated to be 7.46 mg/L (95 % confidence limits: 6.27 – 8.88 mg/L). This corresponds to 5.39 mg a.i./L (95 % confidence limits: 4.53 – 6.42 mg a.i./L) based on the nominal active ingredient.

The NOEC after 48 h was 2.50 mg/L, which corresponds to 1.81 mg a.i./L. The LOEC after 48 h was 5.00 mg/L, which corresponds to 3.62 mg a.i./L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

7.46 mg/L