Reaction mass of 6-ethyl-3-methyloct-5-en-1-ol and 6-ethyl-3-methyloct-6-en-1-ol

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, to GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of 6-ethyl-3-methyloct-5-en-1-ol and 6-ethyl-3-methyloct-6-en-1-ol

Molecular formula:

C11H22O

IUPAC Name:

Reaction mass of 6-ethyl-3-methyloct-5-en-1-ol and 6-ethyl-3-methyloct-6-en-1-ol

Test material form:

other: liquid

Details on test material:

Test substance name: Super Muguet
Chemical name: 6-ethyl-3-methyl-6(5)-octen-1-ol
CAS number: 266330-64-3 & 26330-65-4
Molecular weight: 170.29
Batch number: SC00011582
Purity: 98.3 % (sum of isomers)
Storage: Room temperature (15 - 30 °C)
Expiry date: 20 June 2016

Test solutions

Vehicle:

yes

Details on test solutions:

Nominal test concentrations:
Range finding test: 0.06, 0.6, 6.0 and 60 mg/L
Definitive test: 0.572, 1.831, 5.859, 18.75 and 60 mg/L

Geometric mean measured concentrations:
Definitive test: 0.389, 1.118, 3.768, 13.648 and 44.002 mg/L

Test organisms

Test organisms (species):

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

Details on test organisms:

The test organism, Psuedokirchnerella subcapitata (Strain 278/4), was originally obtained from the Culture Collection of Algae and Protozoa (CCAP) and is a representative species of the freshwater aquatic phytoplankton. This species is recommended for testing in accordance with the OECD regulatory guidelines.
Prior to testing, duplicate starter cultures were prepared and incubated under test conditions to obtain sufficient algal cells in exponential growth and to achieve a starting algae density of 1 x 10^4 cells/mL.
Positive control tests are conducted periodically to assess the performance of the species.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

Temperature incubation: 22.3 - 23.3 °C

pH:

pH increase during the test: 7.60 - 9.30. This increase of more than 1.5 units was thought not to have impacted the test as the control validility criterea were achieved.

Salinity:

no (freshwater)

Nominal and measured concentrations:

Nominal test concentrations:
Range finding test: 0.06, 0.6, 6.0 and 60 mg/L
Definitive test: 0.572, 1.831, 5.859, 18.75 and 60 mg/L

Geometric mean measured concentrations:
Definitive test: 0.389, 1.118, 3.768, 13.648 and 44.002 mg/L

Details on test conditions:

Light Intensity: 7300 Lux
Orbital Shaker Speed: 100 rpm
Test vessel: Sterlie autoclaved glass 250 mL Erlenmeyer (conical) flask, into which 100 mL of the appropriate control or test media was added

Reference substance (positive control):

yes

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.938 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

3.074 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

6.289 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.118 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Effects based on yield and biomass 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. A summary of the EC50 and NOEC resuts based on all three effects (growth rate, yield and biomass is provided below:

Based on geometric mean measured test concentrations, the 72-hour EyC50 and the 0-72 hour EbC50 and ErC50 values were calculated to be 2.715, 2.926 and 6.289 mg/L, respectively.

The corresponding NOEC values for yield biomass and specific growth rate after 72 hours were 1.118 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In a guideline study, conducted according to GLP, Super Muguet was found to have an NOEC (72 hr) of 1.118 mg/L. Based on geometric mean measured test concentrations, the 72-hour EyC50 and the 0-72 hour EbC50 and ErC50 values were calculated to be 2.715, 2.926 and 6.289 mg/L, respectively.

Executive summary:

The effects of Super Muguet on the growth of the unicellular green alga, Psuedokirchneriella subcapitata, were determined during a 72-hour growth inhibition toxicity test conducted in accordance with OECD Chemicals Testing Guideline No. 201 Algae, Growth Inhibition Test.

Based on geometric mean measured test concentrations, the 72-hour EyC50 and the 0-72 hour EbC50 and ErC50 values were calculated to be 2.715, 2.926 and 6.289 mg/L, respectively.

The corresponding NOEC values for yield biosmass and specific growth rate adter 72 hours were 1.118 mg/L.

All validility criterea were met therefore the test was considered valid.

The preferred observational end point in this study is algal growth rate inhibition because it is not dependent on the test design (ECHA guidance Chapter R.7b v1.1) and classification shall be based on the ErC50 (EU CLP regulation No 1272/2008 and its adaption 286/2011). In terms of the NOEC and EC10 values, there is a preference for use of the EC10 value because it is derived from the dose response curve. In contrast the NOEC depends on the experimental design (e.g. the concentrations used in the test). Thus the 72-h EC50 and EC10 based on growth rate are used for classification purposes.