cyclohexadecanone

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:

27 - 30 Mar 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

Jun 1984

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

Dec 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Niedersächsisches Umweltministerium, Hannover, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Control, saturated solution with 100 mg/L test item
- Sampling method: Separate replicates for the test item analysis after 0 h and 72 h were prepared. The samples at the test beginning were prepared without alga and samples at the test end contained the same density of alga as the test replicates and were incubated under test conditions.
- Sample storage conditions before analysis: If necessary, samples were stored at 7 ± 2 °C until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: a saturated solution of 100 mg/L test item was prepared with test medium
- Eluate: 5 mL acetonitrile
- Controls: yes, test medium (without test item)
- Evidence of undissolved material: the test item was clearly dissolved throughout the test

Test organisms (species):

other: Scenedesmus subspicatus

Details on test organisms:

TEST ORGANISM
- Common name: algae
- Strain: SAG 86.81
- Age of inoculum (at test initiation): 4 d old preculture. For the start of the test the preculture was diluted with test medium to receive an initial cell concentration of approximately 1 x 104 cells/mL
- Method of cultivation: Fresh stocks were prepared every month on Z-Agar. Light intensity amounted to 35 - 70 µE/m2 *s for 24 h per day.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

23.0 - 24.0 °C, mean = 23.5 °C

pH:

test start: 8.18 (control), 8.15 (limit concentration)
test end: 9.08 (control), 9.1 (limit concentration)

Nominal and measured concentrations:

control, and 100 mg/L saturated solution (nominal)
< LOQ, and 0.18 mg/L (measured)

Details on test conditions:

TEST SYSTEM
- Test vessel: transparent plactic cuvettes (diameter: 50 mm) with top
- Volume, headspace: Volume: 20 mL; Test volume: 10 mL; Headspace: 10 mL
- Initial cell density: 1*E04 cells/mL
- Control end cell density: mean value = 571349 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, nutrient medium Z according to Lüttge et al. (1994)

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 24 h light
- Light intensity and quality: 60 - 120 µE/m2*s
- pH-values: measured at the beginning of the test (out of 2 additional replicates of each concentration and control) and at the end (from pooled replicates)
- room temperature: measured continuously
- light intensity: measured before test start

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: fluorimeter (Chlorophyll-impulsfluorometer, Kleinfeld)
- Chlorophyll measurement: yes: at the beginning of the test and every 24 h
- microscopic evaluation of cells: at the start and at the end of the test

TEST CONCENTRATIONS
- Range finding study: Yes
- Test concentrations: 1:1.11, 1:10, 1:100, 1:1000 dilutions out of saturated stock solution (100 mg/L)
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.18 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.18 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.18 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.18 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other:

Remarks:

biomass and growth rate

Details on results:

- Exponential growth in the control: yes
- Observation of abnormalities: no morphological abnormalities observed
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50 (72 h) based on biomass growth: 0.48 mg/L potassium dichromate (nominal concentration), 95% confidence interval: 0.42 - 0.55 mg/L
- EC50 (72 h) based on growth rate inhibition: 0.85 mg/L nominal concentration

Reported statistics and error estimates:

One way analysis of variance (ANOVA) and Dunnett´s test of biomass integrals and growth rate, respectively, were carried out for the determination of statistically significant differences compared to control replicates. Before the one way ANOVA a normality test and an equal variance test was done with p-values of 0.05. The alpha-value for the ANOVA and Dunnett´s test was 0.05.

Table 1. Evaluation after 72 h. Statistically significant differences of biomass integrals and growth rates compared to control values are marked (+), not significant differences are marked (-).

Test item [mg/L] initially measured concentration	RE. no	Biomass integral	Inhibition of biomass [%]	Growth rate	Rate-related inhibition [%]
0.18	1	813603	- 15.30	1.37	- 4.48
	2	921826	- 30.64	1.37	- 4.57
	3	905865	- 28.38	1.41	- 7.74
	mv	(+)*880430	- 24.77	(+)* 1.38	- 5.60
Control	1	639602		1.27
	2	731604		1.31
	3	739746		1.32
	4	647418		1.34
	5	723269		1.32
	6	752114		1.30
	mv	705627		1.31

mv = mean value, RE. = replicate,* = significant difference caused by increase of growth, negative inhibitions = increase of growth.

Validity criteria fulfilled:

yes

Conclusions:

ErC50 (72 h) > 0.18 mg/L (measured initial saturated concentration, limit test at the nominal concentration 100 mg/L, OECD 201, Scenedesmus subcapitatus)
ErC10 (72 h) > 0.18 mg/L (measured initial saturated concentration, limit test at the nominal concentration 100 mg/L, OECD 201, Scenedesmus subcapitatus)

Description of key information

ErC50 (72 h) > 0.18 mg/L (measured initial saturated concentration, limit test at the nominal concentration 100 mg/L, OECD 201, Scenedesmus subcapitatus)

ErC10 (72 h) > 0.18 mg/L (measured initial saturated concentration, limit test at the nominal concentration 100 mg/L, OECD 201, Scenedesmus subcapitatus)

Additional information

There is one GLP certified guideline study available, in which the effects of the test substance on the growth of unicellular freshwater green algae was determined.

In a static test Scenedesmus subspicatus was exposed to a saturated nominal stock solution of 100 mg test substance/L as limit concentration for 72 h in controlled conditions. The limit concentration was established in a preliminary range-finding test. The concentrations of the test substance in the saturated test solution was analytically verified by GC-FID at 0 h and 72 h. The saturated solution contained 0.18 mg/L at test initiation (0 h) but the test substance could not be detected after 72 h. It was proposed that the test substance is metabolised during the test.

It was found that the test substance did not inhibit the growth of the freshwater green alga Scendesmus subspicatus at the tested saturated concentration level of 0.18 mg/L. Hence, the ErC10 (72 h) and ErC50 (72 h) were > 0.18 mg/L (measured).