Oct-7-enal

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:

2017-08-01 to 2017-08-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

The pH of the control increased by more than 1.5 unites during the test.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

determination of the concentration of the test item and the converted product (OEA)

Details on sampling:

- Concentrations: all test concetrations and control
- Sampling method: At the start of exposure, 24 and 48 hours after the start of exposure taken out from additional vessels, and the end of exposure taken out of a mixed solution

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution of 100 mg/L for dilution to prepare the test concentrations
- Controls: 6 controls without test item

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Strain: ATCC 22662
- Source (laboratory, culture collection): American Type Culture Collection
- Age of inoculum (at test initiation): 3 days

ACCLIMATION
- Culturing media and conditions (same as test or not): yes

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.8 - 23.2°C

pH:

7.9 - 9.5

Nominal and measured concentrations:

nominal: 0 (control), 0.768, 1.92, 4.80, 12.0, and 30.0 mg/L
geometric mean measured: < LOQ, 0.403, 1.15, 3.18, 9.89 and 27.5 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Sterilized 500 mL Erlenmeyer flask, filled with 100mL/vessel
- Type: closed
- Initial cells density: 0.50×10^4 cells/mL
- Control end cells density: 42×10^4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
One additional replicate for analytical chemistry of the test item was set for 24 and 48 hours, respectively.

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: 87 - 91 µmol·m^-2·s^-1.
- Photoperiod: continuous

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Particle counter; Model COULTER , Z2 (Beckman Coulter, Inc., Instrument No. CC-004), System biological microscope; Model BX41 (Olympus Corporation)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5
Range finding study
- Test concentrations: 0.1, 1.00, 10.0 and 100 mg/L (nominal)
- Results used to determine the conditions for the definitive study: yes

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.43 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence limits: 3.16 - 3.73 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

7.15 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence limits: 7.07 - 7.23 mg/L

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.15 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Observation of abnormalities (for algal test): Many bloated cells were observed in the 27.5 mg/L level. Aggregated cells were observed in the 9.89 mg/L level. The condition of cells in the other concentrations was the same as in the control. In the control, the condition of cells was normal.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: ErC50 (0-3d); 1.3 mg/L (This value was within the normal range of reference substance in the laboratory (mean ± 2S.D.) [mean ± S.D.: 1.00 ± 0.20 mg/L (n = 31)].)
- Other: Reference substance: Potassium dichromate

Table 1: Value of biomass at each time and growth rate with growth inhibition rate

Mean measured concentration   (mg/L)	No.	Cell concentration (×10^4cells/mL)				Growth rate (d^-1)	Inhibition growth rate (%)
						(0 - 72 hours)
		0 hour	24 hours	48 hours	72 hours
Control	A	0.5	2.8	14	42	1.47	-
	B	0.5	2.5	15	42	1.48	-
	C	0.5	2.7	15	42	1.48	-
	D	0.5	2.6	15	41	1.47	-
	E	0.5	2.3	15	40	1.46	-
	F	0.5	2.7	14	45	1.50	-
	Mean	0.5	2.6	14	42	1.48	-
	S.D.	0	0.17	0.51	1.5	0.012	-
0.403	A	0.5	2.4	14	41	1.47	0.61
	B	0.5	2.3	13	45	1.50	-1.6
	C	0.5	2.6	14	42	1.48	-0.081
	Mean	0.5	2.5	14	43	1.48	-0.37
	S.D.	0	0.16	0.44	2.2	0.017	1.2
1.15	A	0.5	2.4	11	43	1.49	-0.77
	B	0.5	2.2	9.9	34	1.41	4.5
	C	0.5	2.3	11	39	1.45	1.8
	Mean	0.5	2.3	10	39	1.45	1.9
	S.D.	0	0.14	0.5	4.5	0.039	2.6
3.18	A	0.5	1.8	8.2	29	1.35	8.2
	B	0.5	1.5	7.8	30	1.36	7.7
	C	0.5	1.7	7.6	31	1.37	6.9
	Mean	0.5	1.7	7.9	30	1.36	7.6
	S.D.	0	0.16	0.26	0.88	0.00981	0.66
9.89	A	0.5	1.1	1.7	2.2	0.489	67
	B	0.5	0.93	1.5	2.2	0.489	67
	C	0.5	0.89	1.7	2.1	0.484	67
	Mean	0.5	0.96	1.6	2.2	0.488	67
	S.D.	0	0.085	0.11	0.02	0.00309	0.21
27.5	A	0.5	0.51	0.63	0.58	0.0511	97
	B	0.5	0.69	0.61	0.64	0.0804	95
	C	0.5	0.61	0.54	0.60	0.0603	96
	Mean	0.5	0.6	0.59	0.61	0.0639	96
	S.D.	0	0.09	0.05	0.027	0.0149	1.0

Table 2: Analytical results for the test item

Nominal concentration (mg/L)	Measured concentration (mg/L) (Percentage of measured concentration versus nominal concentration %)
	At the start	24 hours	48 hours	At the end	Geometric mean
Control	n.d.	n.d.	n.d.	n.d.	-
0.768	0.629 (81.9)	0.615 (80.1)	0.405 (52.7)	0.110 (14.3)	0.403 (52.5)
1.92	1.64 (85.4)	1.49 (77.8)	1.23 (64.2)	0.419 (21.8)	1.15 (60.0)
4.80	4.18 (87.1)	3.90 (81.3)	3.26 (67.8)	1.55 (32.2)	3.18 (66.4)
12.0	10.5 (87.5)	10.1 (83.9)	9.81 (81.7)	9.16 (76.3)	9.89 (82.5)
30.0	27.7 (92.4)	27.3 (91.1)	27.0 (90.0)	28.5 (95.0)	27.5 (91.6)

n.d. : < 0.109 mg/L

Table 3: Analytical results for the converted product OEA

Nominal concentration (mg/L)	Measured concentration (mg/L)
	At the start	24 hours	48 hours	At the end
Control	n.d.	n.d.	n.d.	n.d.
0.768	n.d.	n.d.	0.136	0.531
1.92	n.d.	n.d.	0.259	1.21
4.80	n.d.	n.d.	0.623	2.75
12.0	n.d.	n.d.	0.406	1.34
30.0	n.d.	n.d.	n.d.	0.169

n.d.: < 0.114 mg/L

Table 4: pH of test solutions

Measured concentration (mg/L)	pH
	At the start	At the end
Control	7.9	9.5
0.403	7.9	9.5
1.15	7.9	9.4
3.18	7.9	9.0
9.89	7.9	8.1
27.5	7.9	8.0

Table 5: Temperature and light intensity in the incubator

Time	At the start	1-day	2-day	At the end
Culture temperature (°C)	23.2	23.0	23.0	22.8
Light intensity (µmol m^-2s^-1)	89	91	89	87

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (72h) based on growth rate was determined to be 7.15 mg/L based on mean measured concentration.

Executive summary:

The toxicity of the test item on aquatic algae was determined according to OECD 201 and in compliance with GLP. The algae were exposed to the test substance in concentrations of 0.768, 1.92, 4.80, 12.0, and 30.0 mg/L, equivalent to 0.403, 1.15, 3.18, 9.89 and 27.5 mg/L geometric mean measured concentrations and a control, for 72 hours. Concentrations were analytically verified by GC-FID and differ > 20 % of the nominal concentrations. Therefore all calculations are based on mean measured concentrations. The 72h-EC50 based on growth rate was determined to be 7.15 mg/L. The 72h-EC10 was determined with 3.43 mg/L and the NOEC was determined with 1.15 mg/L.

Description of key information

72h-EC50 (growth rate) = 7.15 mg/L

72h-EC10 (growth rate) = 3.43 mg/L

72h-NOEC (growth rate) = 1.15 mg/L

All values are based on mean measured concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

7.15 mg/L

EC10 or NOEC for freshwater algae:

3.43 mg/L

Additional information

The toxicity of the test item on aquatic algae was determined according to OECD 201 and in compliance with GLP. The algae were exposed to the test substance in concentrations of 0.768, 1.92, 4.80, 12.0, and 30.0 mg/L, equivalent to 0.403, 1.15, 3.18, 9.89 and 27.5 mg/L geometric mean measured concentrations and a control, for 72 hours. Concentrations were analytically verified by GC-FID and differ > 20 % of the nominal concentrations. Therefore all calculations are based on mean measured concentrations. The 72h-EC50 based on growth rate was determined to be 7.15 mg/L. The 72h-EC10 was determined with 3.43 mg/L and the NOEC was determined with 1.15 mg/L.