5-cyclohexadecen-1-one

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study Initiation Date 05 August 2016 - Study Completion Date (signing of final report) 03 March 2017; Experimental Phase - Starting Date 18 November 2016, experimental completion date 03 January 2017.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Principles of method if other than guideline:

There were no Amendments or Deviations to the Study Plan.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

(E)-cyclohexadec-5-enone

Cas Number:

35951-24-7

Molecular formula:

C16H28O

IUPAC Name:

(E)-cyclohexadec-5-enone

Constituent 2

Reference substance name:

(Z)-cyclohexadec-5-enone

Cas Number:

21944-95-6

Molecular formula:

C16H28O

IUPAC Name:

(Z)-cyclohexadec-5-enone

Specific details on test material used for the study:

Name (as stated in the report): Velvione
Batch: VE00413992
Expiration date: January 01, 2017

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

For the determination of the actual test item concentrations, duplicate samples were taken from each treatment at the start of the test.
After 24, 48 hours and at the end of the test (after 72 hours), stability samples (containing algae) were taken in duplicate from all test concentrations and from the solvent control.
For the stability samples with algae, additional flasks containing the test medium with algae were incubated for each treatment under the test conditions. This was necessary as the volume of test solution of the treatment replicates (3 x 15 mL) was too small to perform the analyses. Additional flasks of test medium with 0.0028 and 0.090 mg/L were incubated under test conditions in order to document possible adsorption of the test item onto algae. An additional flask of test medium with 0.090 mg/L was incubated under test conditions but in the dark in order to document a possible photolytic degradation of the test item.
At sampling, samples of 50 mL exposure solution were extracted with 10 mL of MTBE (Tert-butyl Methyl Ether) fortified with an Internal Standard (1,4-Dichlorobenzene) at a concentration of 8.03 mg/L. The samples (aqueous-phase + MTBE) were stored frozen until analysis. The storage stability under these conditions had been confirmed during the pre-study phase.
The concentrations of VELVIONE were analytically measured in at least one of the duplicate samples taken from the solvent control and all test concentrations from the start, 24 hours and end of the test. From the control, one of the duplicate samples was analyzed from the start.

Test solutions

Vehicle:

yes

Remarks:

N,N-dimethylformamide (DMF)

Details on test solutions:

Due to the low solubility and suspected instability of the test item VELVIONE to be subjected to prolonged periods of slow-stirring, the organic solvent N,N-dimethylformamide (DMF) was used to dose the test item. The solvent was chosen based on its solubilizing properties and its relative non-toxicity to daphnia.

Test organisms

Test organisms (species):

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

Details on test organisms:

The test organism used for the study was Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum, occasionally also listed as Raphidocelis subcapitata), Strain No. 61.81 SAG, supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, 37073 Göttingen / Germany). The algae were cultivated at IES Laboratories under standardized conditions according to the test guidelines.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

15 mg/L as CaCO3

Test temperature:

22 °C

pH:

7.4 - 7.6

Nominal and measured concentrations:

The nominal test item concentrations tested were 0.0028, 0.0090, 0.028, 0.090, 0.28 and 0.90 mg/L.
The mean measured (time weighted average) test item concentrations were 0.0013, 0.0054, 0.015, 0.063, 0.23 and 0.68 mg/L.

Details on test conditions:

Test flasks were positioned randomly and repositioned on a daily basis and were continuously illuminated by LED light installed above the flasks. Light intensity at the level of the test solutions was in the range 64 - 68 microE s-1 m-2 and remained within the required +/-15% deviation of intensity.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.68 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.02 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.015 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.15 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.011 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.015 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

A clear concentration-response relationship was observed for both biological parameters growth rate and yield during the exposure period. A significant inhibitory effect on the growth rate and yield of the algae was observed at the end of the test at the concentration of 0.063 mg/L and at all higher test concentrations. An ErC50 (72 hour) value was not attained, since only 40.8% inhibition of Growth Rate was observed at the highest test concentration tested, which equates to the saturation concentration (0.90 mg/L (nominal), 0.68 mg/L measured (TWA)).

Results with reference substance (positive control):

Potassium Dichromate is tested twice per year at the test facility. The 72-hour ErC50 was determined to be 0.9 mg/L at the testing facility (October, 2016) and demonstrated the sensitivity of the test system to be within the recommended range for the guideline (0.9 - 1.5 mg/L).

Any other information on results incl. tables

During the test period of 72 hours the test item concentrations in the test media decreased. The recovery observed at the end of the test in the additional samples incubated without algae

and in the dark were in the same order of magnitude and both slightly higher than in the samples containing algae, showing a slight adsorption of the test item onto the algae.

The mean measured test item concentrations were calculated as the time-weighted means over all measurements.

Due to the decrease of the test item concentrations during the test period of 72 hours, the biological results were related to the mean measured concentrations (time-weighted mean).

All Validity Criteria were met : In the Solvent Control, the biomass increased by a factor of 192-times over the 72 hour period (i.e. greater than the minimum factor of 16); The mean coefficient of variation of the daily growth rates in the Solvent Control (section-by-section growth rates) during the 72 hours was 10% (validity criteria is < 35%); The coefficient of variation of the average specific growth rates in the replicates of the Solvent Control after 72 hours was 1.2% (validity criteria : < 7%).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 72-hour EC50 growth rate was determined to be at the test concentration >0.68 mg/L (based on mean measured concentrations). While, the 72-hour EC10 growth rate was determined to be at the test concentration 0.020 mg/L with 95% confidence limits of 0.012-0.031 mg/L (based on mean measured concentrations).
The 72-hour NOEC was determined to be at the test concentration 0.015 mg/L based on mean measured concentrations).

Executive summary:

The impact of the test item VELVIONE on the growth of the freshwater green algal species Pseudokirchneriella subcapitata was investigated in a 72-hour static test according to the OECD 201 guideline.

The 72-hour EC50 growth rate was determined to be at the test concentration >0.68 mg/L (based on mean measured concentrations) since only 40.8% inhibition of Growth Rate was observed at the highest test concentration tested, which equates to the saturation concentration (0.90 mg/L (nominal), 0.68 mg/L measured (TWA)).  While, the 72-hour EC10 growth rate was determined to be at the test concentration 0.020 mg/L  with 95% confidence limits of 0.012-0.031 mg/L (based on mean measured concentrations).  

The 72-hour NOEC was determined to be at the test concentration 0.015 mg/L based on mean measured concentrations).