Reaction mass of 2-[7-isopropyl-5-methylbicyclo[2.2.2]oct-5-en-2-yl]-1,3-dioxolane and 2-[8-isopropyl-6-methylbicyclo[2.2.2]oct-5-en-2-yl]-1,3-dioxolane

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:

April 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study done to guideline, in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, 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:

2-[8-isopropyl-6-methylbicyclo[2.2.2]oct-5-en-2-yl]-1,3-dioxolane

EC Number:

272-669-9

EC Name:

2-[8-isopropyl-6-methylbicyclo[2.2.2]oct-5-en-2-yl]-1,3-dioxolane

Cas Number:

68901-32-6

Molecular formula:

C15H24O2

IUPAC Name:

2-[8-isopropyl-6-methylbicyclo[2.2.2]oct-5-en-2-yl]-1,3-dioxolane

Test material form:

other: liquid

Details on test material:

Please note that although the substance is stated as the mono-constituent substance 2-(6-methyl-8-(-1-methylethyl)bicyclo(2.2.2)oct-5-en-2(3)-yl-1,3-dioxolane in the report, analytical data on the same batch shows that the test substance is in fact the multi-constituent substance Reaction mass of 2-(7-isopropyl-5(6)-methylbicyclo[2.2.2]oct-5-en-2-yl)-1,3-dioxolane and 2-(8-isopropyl-5(6)-methylbicyclo[2.2.2]oct-5-en-2-yl)-1,3-dioxolane.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples for analytical confirmation of exposure concentrations were taken at the start, after 24 and 72 hours of exposure. Samples taken from all concentrations were analysed. The actual concentrations ranged from 0.90 to 9.5 mg/l, at the start of the test. Measured concentrations decreased to 63-74% of initial at the end of the test. Based on these results, the Time Weighted Average concentrations were calculated to correspond to 0.73, 1.3, 2.5, 4.1 and 7.5 mg/l in solutions containing 10, 18, 32, 56 and 100% WSF, respectively.

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

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

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Nominal and measured concentrations:

Nominal: 10, 18, 32, 56 and 100% of water soluble fraction
Measured: 0.73, 1.3, 2.5, 4.1 and 7.5 mg/L (time weighted average)

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL not determined

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.7 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 4.2-5.4

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: not applicable

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: not applicable

Effect concentrations 5

Duration:

72

Dose descriptor:

EC10

Effect conc.:

3.4 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 3.1-3.8

Effect concentrations 6

Duration:

72

Dose descriptor:

EC10

Effect conc.:

1.2 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 0.9-1.5

Results with reference substance (positive control):

The reference test was carried out to check the sensitivity of the test system used by WIL Research Europe to Potassium dichromate (Merck, Art. 1.04864, Batch K44879664). Closed test vessels were used as to mimic testing a volatile test article and results were compared with standard ‘open’ systems.
Algae were exposed for a period of 72 hours to K2Cr2O7 (Potassium dichromate) concentrations of 0.18, 0.32, 0.56, 1.0, 1.8 and 3.2 mg/l and to a control. The initial cell density was 1.0 x 104 cells/ml.
The EC50 for growth rate inhibition (72h-ERC50) was 1.5 mg/l with a 95% confidence interval ranging from 1.4 to 1.7 mg/l. The historical ranges for growth rate inhibition using standard ‘open’ systems range between 0.82 and 2.3 mg/l. Hence, the 72h-ERC50 for the present test in closed systems is within the historical range.
The EC50 for yield inhibition (72h-EYC50) was 0.41 mg/l with a 95% confidence interval ranging from 0.38 to 0.44 mg/l. The historical ranges for yield inhibition using standard ‘open’ systems lie between 0.43 and 1.1 mg/l. Hence, the 72h-EYC50 for the present test in closed systems was just below this range.
It was concluded that the sensitivity of algae exposed in closed test systems towards Potassium dichromate was not significantly different from the sensitivity of algae exposed in standard ‘open’ reference studies during the past years. These results indicate that the algae are responding normally to toxicant stress under the modified "sealed system" test conditions and that these deviations from test guidelines do not affect the results of this study.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

Under the conditions of the present study with Pseudokirchneriella subcapitata, Glycolierral inhibited growth rate of this fresh water algae species significantly at a TWA concentration of 4.1 mg/l and higher.

The EC50 for growth rate inhibition (72h-ERC50) was beyond the range tested, i.e. exceeded a TWA concentration of 7.5 mg/l (100% WSF, considered to be the solubility limit of this test item under test conditions).

The EC50 for yield inhibition (72h-EYC50) was 4.7 mg/l with a 95% confidence interval ranging from 4.2 to 5.4 mg/l.

The 72h-NOEC and EC10 for growth rate inhibition were 2.5 mg/l and 3.4 mg/L, respectively . The 72h-NOEC and EC10 for yield inhibition were 1.3 mg/l and 1.2 mg/L, respectively.

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.