Methyl non-2-ynoate

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:

October - November 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Methyl non-2-ynoate

EC Number:

203-909-2

EC Name:

Methyl non-2-ynoate

Cas Number:

111-80-8

Molecular formula:

C10H16O2

IUPAC Name:

methyl non-2-ynoate

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

The analytically determined concentrations of dissolved test item in the aqueous phases were 8.0 mg/L (3 hours), 30 mg/L (24 hours) and 41 mg/L (96 hours). The latter is in-line with the determined water solubility in pure water (37.5 mg/L; IES Study 20160079). From these results the stirring time of 96 hours was chosen for preparation of the test media used in the main test.
Additionally a range finder was performed with the lower equilibrated phase (test media) of the slow stirring experiment after a stirring time of 96 hours. This aqueous phase was used as the highest concentrated test medium (loading rate of 100 mg/L) and diluted with test water to obtain the lower concentrated test media (dilution 1:10 and 1:100).

Test solutions

Vehicle:

no

Details on test solutions:

The following test concentrations of Methyl Octine Carbonate were tested: The dilutions 1:460, 1:220, 1:100, 1:46, 1:22 and 1:10 of a stock solution with a loading rate of 100 mg/L. Additionally, a control (test water without test item) was tested in parallel.
The test design included three replicates per loading rate and six replicates of the control.
The test was started using a nominal algal cell density of 5000 cells/mL.

Test organisms

Test organisms (species):

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

Details on test organisms:

The test organism used for the study was Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum), 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.

The test was started using a nominal algal cell density of 5000 cells/mL.

Exponentially growing cultures of this algal species were exposed to the test item over a period of 72 hours and the inhibition of algal growth in relation to control cultures was assessed over several generations.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

The water temperature during the test was maintained at 23 °C

pH:

The pH of the test media was in the range of 7.9 to 8.2 during the test period.

Nominal and measured concentrations:

Nominal concentrations: 1:460, 1:220, 1:100, 1:46, 1:22 and 1:10 dilutions of an equilibrated test item solution with a loading rate of 100 mg/L
Mean measured concentrations: corresponding to the above dilutions were respectively, 0.065, 0.15, 0.29, 0.78, 1.6 and 3.9mg/L

Details on test conditions:

The pH was measured and recorded in each treatment at the start and end of the test. The temperature in the incubator was monitored and recorded continuously. The appearance of the test media was also visually controlled and recorded daily during the exposure period.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.83 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence interval: 0.81-0.85

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.29 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence interval: 0.27-0.30

Details on results:

Effects based on yield were also reported (see attached full study report ). However, the preferred observational endpoint in the algal inhibition study is growth rate because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1). The EU CLP regulation (No 1272/2008 and its adaption 286/2011) also states that classification should be based on the ErC50. Thus only the effects based on growth rate are presented in the above "effects concentration" table. Furthermore, the preferred observational endpoint in long-term studies is the EC10 value because it is derived from the dose response curve. In contrast the NOEC strongly depends on the experiment design (e.g. the concentrations used in the test). Thus, only the EC10 is presented in the above "effects concentration" table. The NOEC values are available in the full study report.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

The EC50 based on growth rate was 0.83 mg/L with 95% confidence limits of 0.81 and 0.85 mg/L (based on mean measured concentrations).

EC10 based on growth rate was 0.29 mg/L with 95% confidence limits of 0.27 and 0.30 mg/L (based on mean measured concentrations).