Ethyltris(2-hydroxyethyl)ammonium ethyl sulphate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: Ethyltris(2-hydroxyethyl)ammonium ethyl sulphate
Product Description: Triethanolamine DES Quat
CAS No.: 31774-90-0
Physical state: colourless to yellow viscous liquid at 20 °C
Batch No.: PFS-755-175
Re-certification date of batch: 21 April 2018
Purity: 100 % (UVCB, water content 0.33 % (w/w))
pH, 5% in water 7.85
Acid Value , mg KOH/g 38.45
Moisture, % 0.33
Total Amine, mg/g 33.10
Viscosity,cps, #4@60,25C 1580
Stability: stable under test conditions
Storage condition of test material: Room temperature, protected from light

Analytical monitoring:

yes

Details on sampling:

Chemical analysis of the test item concentrations in the test solutions was performed to determine exposure concentration and stability of the test item during exposure. Substance specific analysis was performed at the test site menal GmbH. The samples were filled into 10 mL glass vials and stored in the freezer (≤ -18 °C). The sampling was conducted according to the following specification:

- After 0 h, 24 h and 48 h exposure, both additional vessels of NC (0 mg/l), A (1.0 mg/l), C (10.3 mg/l) and E (105 mg/l) were sampled; one sample per replicate: 2 samples of 6 mL per treatment group.

- At the end of the test (72 h), both additional vessels and 2 replicates of the test vessels from NC (0 mg/l), A (1.0 mg/l), C (10.3 mg/l) and E (105 mg/l) were sampled; one sample per replicate: 4 samples of 6 mL per treatment group.

Of each sampled treatment, one of the analytic samples from 0 h, 24 h, 48 h and 72 h was sent to the analytical laboratory at the test site menal GmbH. The remaining samples were stored as retain samples in the freezer (≤ -18 °C) until finalization of the study.

Vehicle:

no

Details on test solutions:

Preparation of the test treatment and control:
The stock solution was prepared by adding 116.6 mg test item (including a factor of 1.11 to take into account the dilution caused by addition of the algal inoculum) to 1000 mL test medium and shaking for 1 h using an overhead shaker. This stock solution was used as highest test item
concentration in the test. Into each test vessel, 50 mL test solution (including algal inoculum) was transferred. The negative control (NC) and the further test item concentrations were prepared by diluting the stock solution with test medium (dilution factor 3.2).
Test item concentration:0 mg/L, 1.0 mg/L, 3.2 mg/L, 10.3 mg/L, 32.8 mg/L, 105 mg/L

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The test organism Raphidocelis subcapitata (Strain No. 61.81 SAG) originates from the Culture Collection of Algae at the University of Goettingen and was cultivated in suspension culture. The strain used for this study has been cultured at Hydrotox GmbH since May 2016. Twice a week, the stock suspension is inoculated into fresh Holm-Hansen medium (composition: 496 mg/L NaNO3, 39 mg/L K2HPO4, 75 mg/L MgSO4×7H2O, 36 mg/L CaCl2×2H2O, 58 mg/L Na2CO3, 10 mg/L Na2EDTA×2H2O, 3 mg/L citric acid, 3 mg/L iron citrate, 0.1144 mg/L H3BO3, 0.0724 mg/L MnCl2× 4H2O, 0.0088 mg/L ZnSO4×7H2O, 0.0032 mg/L CuSO4×5H2O, 0.0010 mg/L Na2MoO4×2H2O, 0.0016 mg/L CoCl2×6H2O) under axenic conditions to keep it in exponential growth.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

The test was performed with OECD TG 201 medium according to OECD 201 (2006).

Test temperature:

The temperature during the exposure was 22.8 - 23.3 °C.

pH:

The pH was 7.7 – 7.9 in the control and 7.7 – 7.9 in the test item treatment.

Dissolved oxygen:

not specified

Salinity:

The test was performed with OECD TG 201 medium according to OECD 201 (2006).

Conductivity:

The test was performed with OECD TG 201 medium according to OECD 201 (2006).

Nominal and measured concentrations:

The measured test item concentrations in the test item treatments were 92.0 – 101.9 % of the nominal concentrations. As the measured test item concentrations are within ± 20 % of the nominal concentrations, according to OECD 201 (2006), all results are given in relation to the nominal test item concentrations.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 105 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

growth rate

Remarks on result:

other: CI: n.d.

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

9.95 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: CI: 1.08 – 91.89 mg/l

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

32.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

10.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

35.04 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Basis for effect:

biomass

Remarks on result:

other: CI: 0.94 – 1171.63 mg/l

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.81 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: CI: 0.14 – 57.26 mg/l

Results with reference substance (positive control):

Quality assurance takes place at regular intervals by testing the sensitivity of the test organisms to the reference item potassium dichromate. The recent quality testing was performed in February 2017 which resulted in an ErC50 of 0.95 mg/L (CL 95 %: 0.61 - 1.47 mg/L) and, therefore, is within the recommended range of 0.6 - 1.03 mg/L. The EyC50 was 0.06 mg/L (CL 95 %: 0.00 - 1.29 mg/L).

Reported statistics and error estimates:

With the statistical software ToxRat 3.2.1 (ToxRat Solutions GmbH, Alsdorf), ECx and LOEC/NOEC for yield and growth rate were determined.

Criteria of validity

- The biomass (cell concentration) in the control has increased by a factor of 83.6 and therefore ≥ 16 during the test period.  

- The mean coefficient of variation for section-by-section growth rate (day 0 - 1, 1 - 2 and 2 - 3) in the control is 30.5 % and therefore ≤ 35 %.

- The coefficient of variation of average specific growth rate during the test period in the control replicates is 3.9 % and therefore ≤ 7 %.

The test is valid according to OECD Test Guideline 201 (23 March 2006).

Table 1: Inhibition of growth rate after 24 h, 48 h and 72 h exposure

Nominal test item concentration [mg/l]	Inhibition of growth rate [%]
	24 h	48 h	72 h
NC	-	-	-
1.0	-6.0	0.1	-0.4
3.2	2.5	4.8	1.3
10.3	3.7	5.4	2.1
32.8	88.9	52.9	31.3
105	40.4	24.2	17.2

Table 2: Inhibition of yield after 24 h, 48 h and 72 h exposure

Nominal test item concentration [mg/l]	Inhibition of growth rate [%]
	24 h	48 h	72 h
NC	-	-	-
1.0	-9.5	-1.8	-10.7
3.2	5.3	14.7	7.0
10.3	7.1	15.9	9.6
32.8	93.1	82.2	76.1
105	51.9	51.6	50.2

Validity criteria fulfilled:

yes

Conclusions:

An algae, growth inhibition test with Raphidocelis subcapitata was performed with five concentrations between 1.0 mg/L and 105.0 mg/L of the test item. The following results were obtained:
Growth rate: EC50: > 105 mg/L (CI: n.d.)

Executive summary:

An algae, growth inhibition test with Raphidocelis subcapitata was performed with five concentrations between 1.0 mg/L and 105.0 mg/L of the test item. As the measured test item concentrations are within ± 20 % of the nominal concentrations, according to OECD 201  (2006), all results are given in relation to the nominal test item concentrations. All validity criteria were fulfilled. The test is valid according to OECD Test Guideline 201 (23 March 2006).

The following results were obtained:

Growth rate:

EC50: > 105 mg/L (CI: n.d.)

Yield:

EC50 : 35.04 mg/L (CI: 0.94 – 1171.63)*

*due to reduce inhibition of algae growth at highest concentration (105 mg/l) compared to second highest concentration (32.8 mg/l).

Description of key information

An algae, growth inhibition test with Raphidocelis subcapitata was performed with five concentrations between 1.0 mg/L and 105.0 mg/L of the test item. The following results were obtained:

Growth rate: EC50: > 105 mg/L (CI: n.d.)

Key value for chemical safety assessment

EC50 for freshwater algae:

105 mg/L

EC10 or NOEC for freshwater algae:

9.95 mg/L