4-(4-methoxyphenyl)butan-2-one

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:

2016-03-29 to 2016-04-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2011

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0, 6.25, 12.5, 25, 50 and 100 mg/L
- Dilution: acetonitril:HPLC water (40:60)
- Sample storage conditions before analysis: stored at 6 +/- 2 °C. Prepared samples were stored at room temperature.

Vehicle:

not specified

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: HINDÄK, SAG 61.81
- Source: available in study report
- Method of cultivation: Nutrient medium Z according to Lüttge et ai. (1994); Fresh stocks are prepared every month on Z-Agar. Light intensity amounted to 35-70 µE m-2 s-1 for 24 hours per day.
- Age of inoculum (at test initiation): 3 days old pre-culture

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

Microscopic evaluation of the cells at the start and the end of exposure was carried out. The cells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.

Test temperature:

21-24 °C (controlled at +/- 2°C)

pH:

ranging from 7.87 to 9.47

Nominal and measured concentrations:

Nominal concentrations: 6.25 - 12.5 - 25.0 - 50.0 - 100 mg/L.
Measured concentrations (0 h): 6.56 - 13.0 - 25.1 - 48.6 - 97.6 mg/L
Measured concentrations (72 h): 6.37 - 12.9 - 25.5 - 49.1 - 97.9 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: flask
- Type: flasks cotton plug, with headspace
- Initial cells density: nominal -> approximately 5 x 103- 104cells/mL; current: 6305 cells/mL
- Control end cells density:
- No. of organisms per vessel: 6305 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Agitation: Test containers were placed on a rotary shaker and oscillated at approximately 70 rpm.

GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: TG OECD medium


OTHER TEST CONDITIONS
- Photoperiod: light 24 h/day
- Light intensity and quality: Approximately 60 - 120 µE m-2 s-1; light homogeneity within 15 % over incubation area


EFFECT PARAMETERS MEASURED:
- Chlorophyll measurement: yes, excitation at 436 nm, emission at 685 nm
- Frequency: daily measurements

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: 100 % inhibition at 100 mg/L and 4 and 20 % inhibition at 10 mg/L for growth and yield, respectively

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

38.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % confidence interval: 36.6-39.6 mg/L

Remarks:

Nominal concentrations verified by measurements

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

19.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % confidence interval: 17.7 - 20.8 mg/L

Remarks:

Nominal concentrations verified by measurements

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

12.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

Nominal concentrations verified by measurements

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

20.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield inhibition

Remarks on result:

other: 95 % confidence interval: 18.5-22 mg/L

Remarks:

Nominal concentrations verified by measurements

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

13.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield inhibition

Remarks on result:

other: 95 % confidence interval: 11.9-15.2 mg/L

Remarks:

Nominal concentrations verified by measurements

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

12.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield inhibition

Remarks on result:

other:

Remarks:

Nominal concentrations verified by measurements

Details on results:

- Exponential growth in the control (for algal test): yes
- Unusual cell shape: no morphological abnormalities

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 0.564 mg/L growth rate inhibition (valid range: 0.797 +/- 0.428 mg/) and 0.322 mg/L yield inhibition (valid range: 0.415 +/- 0.275 mg/L).

Reported statistics and error estimates:

ECx-values of growth rate and yield inhibition with confidence intervals after 72 hours were calculated by sigmoidal dose- response regression with GraphPad Prism.

The NOEC / LOEC was determined by calculation of statistically significant differences of growth rate and yield using Williams Sequential t-test Procedure. A Shapiro-Wilk's Normality test and a Levene’s Equal Variance test were done first. P-values for both Normality and Equal Variance tests are 0.05. The a-value (acceptable probability of incorrectly concluding that there is a difference) is a = 0.05.

The mean cell densities measured are reported here:

Nominal test item concentration (mg/L)	no. of replicates	Mean cell density (cells/mL)
		0h	24h	48h	72h
100	3	6305	11209	8165	3784
50	3	6305	13720	14431	35496
25	3	6305	19666	89488	646958
12.5	3	6305	27685	331112	2078334
6.25	3	6305	29255	398052	2453092
control	6	6305	25220	346667	2199062

This translates to following growth rates, yield and inhibition:

Nominal test item concentration (mg/L)	no. of replicates	Mean growth rate (d-1)	Mean inhibtion of growth rate (%)	Mean yield (cells/mL)	Mean inhibtion of yield (%)
100	3	-0.174	100	-2521	100
50	3	0.575	71	29191	99
25	3	1.53	21	640653	71
12.5	3	1.93	1	2072029	6
6.25	3	1.99	-2	2446787	-12
control	6	1.95		2192757

The section-by-section and average growth rates of the control group are as follows:

replicate	0-24h	24-48h	48-72h	Mean (0-72h)	SD (+/-)	CV (%)	Mean CV (%)
1	1.41	2.46	1.77	1.88	0.533	28.4	32.3
2	1.34	2.7	1.77	1.94	0.698	36
3	1.52	2.63	1.78	1.98	0.582	29.4
4	1.43	2.45	1.99	1.96	0.51	26.1
5	1.2	2.79	1.92	1.97	0.797	40.5
6	1.39	2.69	1.86	1.98	0.657	33.2
			Mean	1.95
			SD (+/-)	0.04
			CV (%)	1.91

Measured exposure concentrations during the Definitive Test:

Sampling date	2016-03-29 Fresh medium (0 hours)		2016-04-01 End of the exposure (72 hours)
Start of analysis	2016-03-29		2016-04-01
Nominal conc. (mg/L)	Measured conc. (mg/L)	%	Measured conc. (mg/L)	%
100	97.6	98	97.9	98
50.0	48.6	97	49.1	98
25.0	25.1	100	25.5	102
12.5	13.0	104	12.9	103
6.25	6.56	105	6.37	102
Control	< LOQ		< LOQ

 

Validity criteria fulfilled:

yes

Conclusions:

After an exposure of 72 h, the test item was found to inhibit the growht of Pseudokirchneriella subcapitata. The reported EC50-values are 38.1 mg/L for growth rate inhibition and 20.2 mg/L when yield inhibition was studied. The 72-hour EC10-values for inhibition of growth rate and yield were 19.2 and 13.4 mg/L, respectively.

Executive summary:

For this endpoint, one study is available in which the effect of the test item on growth of freshwater green alga Pseudokirchneriella subcapitata after 72 hours exposure was assessed according to OECD 201. The nominal concentrations tested were 6.25 - 12.5 - 25.0 - 50.0 - 100 mg/L. Validity criteria were fulfilled with this test set-up. The test item was found to inhibit the growth of Pseudokirchneriella subcapitata. The 72-hour EC50-values with 95 % confidence intervals for both inhibition of growth rate (ErC50) and yield (EyC50) were 38.1 (36.6 - 39.6) and 20.2 (18.5 - 22.0) mg/L. The EC10-values for inhibition of growth rate and yield after 72 hours were 19.2 and 13.4 mg/L, respectively.

Description of key information

OECD 201 (Pseudokirchneriella subcapitata): ErC50 = 38.1 mg/L; ErC10 = 19.2 mg/L (nominal concentrations)

Key value for chemical safety assessment

EC50 for freshwater algae:

38.1 mg/L

EC10 or NOEC for freshwater algae:

19.2 mg/L

Additional information

For this endpoint, one study is available in which the effect of the test item on growth of freshwater green alga Pseudokirchneriella subcapitata after 72 hours exposure was assessed according to OECD 201. The nominal concentrations tested were 6.25 - 12.5 - 25.0 - 50.0 - 100 mg/L. Validity criteria were fulfilled with this test set-up. The test item was found to inhibit the growth ofPseudokirchneriella subcapitata. The 72-hour EC50-values with 95 % confidence intervals for both inhibition of growth rate (ErC50) and yield (EyC50) were 38.1 (36.6 - 39.6) and 20.2 (18.5 - 22.0) mg/L. The EC10-values for inhibition of growth rate and yield after 72 hours were 19.2 and 13.4 mg/L, respectively.