Diesters of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid

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:

20 Jan - 23 Jan 2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Guideline study with acceptable restrictions: Initial measured concentration was used to evaluate NOEC and EC50 in spite that the concentration after 72 hours was notably lower than at inition and not within 20 % of nominal concentration. Analytical purity is only 77.2%.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Nominal concentration was used to evaluate NOEC and EC50 in spite that the concentration after 72 hours was not within 20 % of nominal concentration.

GLP compliance:

yes

Remarks:

according to the Japanese GLP Standard

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Samples were taken directly from each vessel.
- Sample storage conditions before analysis: no storage before analysis

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Test substance was measured and mixed with vehicle. Purified water was added bit by bit to prepare the stock solution (1000 mg/L). Stock solution was diluted with test media.
- Controls: blank control and vehicle control
- Chemical name of vehicle: HCO-40
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): 10000 mg/L in a stock solution, 1 mg/L in final concentration
- Evidence of undissolved material: Test water was clear and colourless at the study initiation.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: algae
- Strain: ATCC22662
- Source: American Type Culture Collection
- Age of inoculum: ≤ 3 days
- Method of cultivation: on a shaker

ACCLIMATION
- Acclimation period: 16 Jan - 20 Jan 2004
- Culturing media and conditions: same as test

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

22.8 - 23.2; (23 ± 2 °C)

pH:

7.9 - 10.0

Nominal and measured concentrations:

Nominal concentration: 0.100 mg/L
Measured concentration: 0.0845 mg/L at the study initiation, 0.0019 mg/L at the end of the study

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer-flask
- Type: closed with air-permeable cap
- Material: glass; Size: 300 mL; Fill volume: 100 mL
- Initial cells density: 10000 cells/mL
- Control end cells density: 3056200 ± 155000 cells/mL
- No. of vessels per concentration: 3
- No. of vessels per control: 3
- No. of vessels per vehicle control: 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no
- Intervals of water quality measurement: Temperature and ph were measured at 24, 48 and 72 hours after test begin.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no adjustment
- Photoperiod: continuously
- Light intensity and quality: 4000 lux

EFFECT PARAMETERS MEASURED: Algal growth was recorded after 72h test duration.
- Determination of cell concentrations: counting chamber; electronic particle counter

TEST CONCENTRATIONS
- Range finding study: performed
- Test concentrations: 0.1 mg/L
- Results used to determine the conditions for the definitive study: Growth rate was 92% compared with control group and 94 % with vehicle control group. The measured concentration was 0.001 mg/L after 72 hours.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (analytical grade)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.085 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.085 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.085 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.085 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control: yes
- Observation of abnormalities: No abnormality was observed.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 0.432 ± 0.074 mg/L

Reported statistics and error estimates:

Student's t-test for NOEC

Table 1: Measured concentration of the test substance

Nominal Conc. [mg/L]	Measured Conc. [mg/L], (Percent of nominal)
	0 h	72 h
Control	<0.1	<0.1
Solvent control	<0.1	<0.1
0.100	0.0845 (85)	0.0019 (2)

Table 2: Growth inhibition [%]

Nominal Concentration [Measured conc. at 0 h] [mg/L]	Biomass	Growth rate (24-48 h)	Growth rate (24-72 h)
	Inhibition [%] *	Inhibition [%] *	Inhibition [%] *
Control	-	-	-
Solvent control	-	-	-
0.100 [0.0845]	- 6.5	2.4	- 0.4

*: Values are the growth inhibition [%] relative to the solvent control.

Description of key information

In a test on algae exposure to 0.1 mg/L bis(2-ethylhexyl) azelate (measured initial concentration 0.0084 mg/L) did not lead to decreased growth rates or inhibition of biomass. The EC50 for growth rate is > 0.0084 mg/L (measured) and the NOEC is 0.0084 mg/L (measured). As this concentration is above the reported water solubility of bis(2-ethylhexyl) azelate, no toxicity of this substance is expected up to maximum solubility (MOE 2004). Therefore the NOELR is set at 0.1 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.1 mg/L

EC10 or NOEC for freshwater algae:

0.1 mg/L

Additional information

The substance tested is considered a close analogue of diesters of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid and a worst case due to the presence of 2-ethylhexan-1-ol as part of the starting materials of both diesters of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid and bis(2-ethylhexyl) azelate. Therefore the outcome of the study that indicates no toxicity at the water solubility level is considered representative for diesters of alcohols, C7-9-iso-, C8-rich, 2-ethylhexyl and nonanedioic acid (see rationale for read-across)