6-methylhept-5-en-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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

no GLP. Test design issues, hence recalculation of ECx values.

Qualifier:

according to guideline

Guideline:

other: German standard DIN 38412, L 9

GLP compliance:

no

Analytical monitoring:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM- Strain: CHODAT (SAG 86.81)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.3 °C

pH:

7.73 - 9.19

Nominal and measured concentrations:

Nominal test concentration (mg/l):10, 25, 50, 100, 250, 500, control, solvent control

Details on test conditions:

The number of cells were measured daily using fluorescence method at 300 - 780 nm (pulsed fluorometry) TEST DESIGN- 4 replicates per concentration

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

30.13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 116 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: effective concentration due to volatility

Details on results:

Due to a moderate volatility in an experiment using 100 mg and 200 mg of 6-methylhept-5-en-2-one, but without test organisms, the evaporation over 72 hours was observed. After 72 h approximately 37 % and 39 % of the test substance were evaporated (geometric mean of of all TOC values between 0 h and 96 h), respectively. Therefore, the ErC50(72h) can be corrected to be approximately 116 mg/l based on 39% evaporation. For the EbC50(72h) the effective value is 126 mg/l based on 39% evaporation.Neither growth promotion nor autofluorescence were observed. The effect values for the endpoint growth rate are: ErC10 (72h) = 30.13 mg/l (95% confidence: 9.1-99.9 mg/l) The effect values for the endpoint biomass are: NOEC (72h) < 10 mg/l EbC10 (72h) = 31.12 mg/l (95% confidence: 11.4-84.5 mg/l) EbC50 (72h) = 208.20 mg/l (95% confidence: 71.3-607.7 mg/l) In spite of the increased pH values after 96h in the treatments 10 and 25 mg/l a pH effect can be excluded, because the cell density and the growth rate, as relevant parameter, were not affected.

Reported statistics and error estimates:

The ECx values were calculated according to Tallarida and Jacob (1979).

Description of key information

Acute toxicity to aquatic algae was investigated in Scenedesmus subspicatus (Desmodesmus subspicatus) accordance with DIN 38 412 in a static test, not under GLP. Due to a moderate volatility in an experiment using 100 mg and 200 mg of  6-methylhept-5-en-2-one, but without test organisms, the evaporation over 72 hours was observed. After 72 h approximately 37 % and 39 % of the test  substance were evaporated (geometric mean of of all TOC values between 0  h and 96 h), respectively. Therefore, the ErC50(72h) can be corrected to be approximately 116 mg/l based on 39% evaporation. For the EbC50(72h)  the effective value is 126 mg/l based on 39% evaporation. Neither growth promotion nor autofluorescence were observed.  The effect values for the endpoint growth rate are: ErC10 (72h) = 30.13 mg/l (95% confidence: 9.1-99.9 mg/l). The effect values for the endpoint biomass are: NOEC (72h) < 10 mg/l, EbC10 (72h) = 31.12 mg/l (95% confidence: 11.4-84.5 mg/l) EbC50 (72h) = 208.20 mg/l (95% confidence: 71.3-607.7 mg/l). In spite of the increased pH values after 96h in the treatments 10 and 25  mg/l a pH effect can be excluded, because the cell density and the growth  rate, as relevant parameter, were not affected.

Key value for chemical safety assessment

EC50 for freshwater algae:

116 mg/L

EC10 or NOEC for freshwater algae:

30.13 mg/L