Isotridecanol, ethoxylated

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:

02 - 05 Mar 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

1992

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: The two highest concentrations, 2.06 and 4.54 mg/L, were sampled at 0, 24, 48 and 72 h.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared by adding 1000 mg test item in 1000 mL deionized water. From the first solution, a second stock solution was prepared with a dilution of 10/500.; required aliquots of stock solution were taken under stirring and pipetted into test vessels.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source: Pflanzenphysiologisches Institut der Universität Göttingen, Germany obtained at 23 Oct. 1997
- Method of cultivation: 3 - 4 days preincubation in test medium

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24.2 - 24.9°C

pH:

7.9 - 9.0

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 0.04, 0.088, 0.194, 0.426, 0.937, 2.06 and 4.54 mg/L
Measured concentrations: 1.5 - 2.2 (2.06), 2.1 - 3.8 (4.54) mg/L, mean recovery: 78.1%

Details on test conditions:

TEST SYSTEM
- Test vessel: 300 mL Erlenmeyer flask
- Fill volume: 100 mL
- Initial cells density: 10^4 cells/mL
- Control end cells density: 1.2 x 10^6 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to EU Method C.3
- Culture medium different from test medium: no
- Intervals of water quality measurement: 0 and 72 hours (pH)

OTHER TEST CONDITIONS
- Photoperiod: continuous light
- Light intensity and quality: approx. 2000 lux

EFFECT PARAMETERS MEASURED: cell numbers (24, 48, 72 h)
- Determination of cell concentrations: Coulter counter

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.328 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes

Reported statistics and error estimates:

Probit analysis

Table 1: Cell numbers after 72 hours

Conc. [mg/1]	Nr	Coulter-Counter [cellsImL]	Coulter-Counter [cellsImL]	Single values [cells/mL]	Mean [cells/mL]
0 0 0	1 2 3	1,17E+06 1,21 E+06 1,08E+06	1,18E+06 1,22E+06 1,08E+06	1,2E+06 1,2E+06 1,1E+06	1,2E+06
0,04 0,04 0,04	1 2 3	1,27E+06 1,29E+06 1,06E+06	1,26E+06 1,26E+06 1,08E+06	1,3E+06 1,3E+06 1,1E+06	1,2E+06
0,088 0,088 0,088	1 2 3	9,56E+05 1,25E+06 1,36E+06	9,63E+05 1,26E+06 1,33E+06	9,6E+05 1,3E+06 1,3E+06	1,2E+06
0,194 0,194 0,194	1 2 3	1,15E+06 1,32E+06 1,24E+06	1,14E+06 1,26E+06 1,21E+06	1,1E+06 1,3E+06 1,2E+06	1,2E+06
0,426 0,426 0,426	1 2 3	1,18E+06 1,10E+06 1,08E+06	1,16E+06 1,09E+06 1,09E+06	1,2E+06 1,1E+06 1,1E+06	1,1E+06
0,937 0,937 0,937	1 2 3	1,03E+06 1,17E+06 9,51E+05	1,03E+06 1,18E+06 9,54E+05	1,0E+06 1,2E+06 9,5E+05	1,1E+06
2,06 2,06 2,06	1 2 3	4,95E+05 4,99E+05 6,10E+05	5,04E+05 4,90E+05 6,32E+05	5,0E+05 4,9E+05 6,2E+05	5,4E+05
4,54 4,54 4,54	1 2 3	1,47E+05 9,23E+04 5,08E+04	1,48E+05 9,51E+04 4,86E+04	1,5E+05 9,3E+04 4,9E+04	9,7E+04
4,54 4,54 4,54	1 2 3			#DIV/0! #DIV/0! #DIV/0!	#DIV/0!
4,54 4,54 4,54	1 2 3			#DIV/0! #DIV/0! #DIV/0!	#DIV/0!

Table 2: Growth rate

Concentration [ mg/L]	24 hours [cells/(mL*h)]	48 h [c/(mL*h)]	72 h [c/(mL*h)]
0	0,0726	0,0753	0,0660
0,04	0,0800	0,0804	0,0665
0,088	0,0787	0,0782	0,0663
0,194	0,0795	0,0765	0,0667
0,426	0,0754	0,0751	0,0655
0,937	0,0771	0,0744	0,0647
2,06	0,0633	0,0600	0,0554
4,54	0,0344	0,0301	0,0315
4,54	#DIV/0!	#OIV/0!	#DIV/0!
4,54	#DIV/0!	#DIV/0!	#DIV/0!

Validity criteria fulfilled:

not specified

Description of key information

ErC50 (72h): 3.4 mg/L (meas. arith. mean, OECD 201)

ErC10 (72h): 1.33 mg/L (meas. arith. mean, OECD 201)

Additional information

The effect of Isotridecanol, ethoxylated, < 2.5 EO on the growth rate of the freshwater algae Desmodesmus subspicatus was investigated in a study set up according to EU Method C.3.

The algae were exposed for 72 hours to nominal test substance concentrations of 0.04, 0.088, 0.194, 0.426, 0.937, 2.06 and 4.54 mg/L. The two highest concentrations were sampled daily for analytical dose verification by LC/UV. The arithmetic mean recovery rate was 78.1%. Based on the algal growth rate an EC50 (72 h) of 3.4 mg/L (meas. arith. mean) was determined. The determined ErC10 (72 h) was 1.33 mg/L (meas. arith. mean).