N-[2-[bis(carboxymethyl)amino]ethyl]-N-(1-oxononyl)Glycine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2022-02-16 to 2022-11-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Each test solution is prepared separately as Water accomodated fraction (WAF) in OECD TG 201 test medium and shaking for 24 hours in an overhead shaker. After 1 h of sedimentation the middle fraction of the test solution is used for the test.
- Controls: negative control with nutrition medium only
- Test concentration separation factor: 2

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Raphidocelis subcapitata
- Strain: 61.81 SAG
- Source (laboratory, culture collection): Culture Collection of Algae (SAG) at the University of Goettingen
- Age of inoculum (at test initiation): A pre-culture with a starting concentration of 0.5 – 1 × 105 cells/mL is prepared in OECD TG 201 medium and incubated under the same conditions as for the definite test. After 4 d, the algae (in exponential growth phase) are used as inoculum in the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21 - 24 °C; constant within ±2 °C

pH:

7.8 - 7.9 in control and 6.0 - 7.8 in the test item treatment

Nominal and measured concentrations:

nominal: 6.25, 12.5, 25, 50 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL Erlenmeyer flasks
- Initial cells density: 0.07 x 10^5 cells/mL
- Control end cells density: 6.8 × 10^5 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: particle counter and corresponding fluorescence with the microplate reader.
- Chlorophyll measurement: measuring the surrogate parameter chlorophyll fluorescence (excitation at 465 nm, emission at 670 nm)

TEST CONCENTRATIONS
Main test:
- 6.25, 12.5, 25, 50 and 100 mg/L; Spacing factor for test concentrations: 2

Range finding study
- Test concentrations: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: 4.7, 10.0 and 31.1 % growth inhibition at 1, 10 and 100 mg/L, respectively.

Reference substance (positive control):

no

Remarks:

The recent quality testing was performed in February 2022 (GLP 1717) which resulted in an ErC50 (72 h) of 1.03 mg/L (CL 95 %: 0.93 - 1.13 mg/L) and an EyC50 (72 h) of 0.63 mg/L (CL 95 %: 0.44 — 0.89 mg/L).

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Mean growth rate inhibition after 72 h was 44.1, 41.4, 40.6, 25.4 and 36.8 % for test concentrations of 6.25, 12.5, 25, 50 and 100 mg/L, respectively.
The range finding test showed 4.7, 10.0 and 31.1 % growth inhibition at 1, 10 and 100 mg/L, respectively.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the test no significant changes were observed in algal growth. The 72h-ErC50 values was determined to be > 100 mg/l.

Executive summary:

In a toxicity study on algae, R. subspicatus was exposed to the test material at the following nominal concentrations: 6.25, 12.5, 25, 50 and 100 mg/l. No specific analysis of these concentrations is reported. The 72h-ErC50 value was determined to be > 100 mg/l. In a range finding test, growth inhibitions of 4.7, 10.0 and 31.1% were determined in nominal concentrations of 1, 10 and 100 mg/L, respectively.

Description of key information

An 72h ErC50 > 100 mg/L was determined.