4-(tricyclo[5.2.1.02,6]dec-8-ylidene)butyraldehyde

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:

The study was conducted between 18 October 2016 and 10 March 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

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-(tricyclo[5.2.1.02,6]dec-8-ylidene)butyraldehyde

EC Number:

250-078-7

EC Name:

4-(tricyclo[5.2.1.02,6]dec-8-ylidene)butyraldehyde

Cas Number:

30168-23-1

Molecular formula:

C14H20O

IUPAC Name:

4-[(8Z)-tricyclo[5.2.1.0^{2,6}]decan-8-ylidene]butanal

Test material form:

liquid

Specific details on test material used for the study:

Test Item: Dupical
Batch Number: VE00422788
Purity: 98.0%
Appearance: colourless to pale yellow liquid
Expiry date: 2017-01-28
Recommended storage: Dry, well-ventilated, hermetically sealed at ambient temperature (10 - 30 °C), protected against light.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

All concentration levels and the control were analytically verified via GC-FID after 0 hours (start of exposure), 24 hours, 48 hours and 72 hours (end of the exposure).
Separate replicates for the test item analysis after 0, 24, 48 hours and 72 hours were prepared with algae at the start of the exposure and incubated under test conditions until analysis.

Test solutions

Vehicle:

yes

Remarks:

0.1 mL/L acetone used as solvent. Solvent Control incorporated in to study set-up.

Details on test solutions:

For the preparation of the test concentrations of the test item DUPICAL, appropriate stock solutions were prepared in acetone (solvent). The test item is an aldehyde and thus likely to undergo significant oxidation in aquatic toxicity testing media. Aim of this procedure was to achieve sufficient exposure concentrations of the test item near the nominal concentrations. High amounts of metabolites of the test item should be avoided by keeping the preparation period of the test solutions as short as possible by using a solvent. The stock solutions were prepared in measuring flasks (10 mL capacity) by direct pipetting of appropriate amounts of the test item into the measuring glass flasks. Therefore, the density was taken into account. Thereafter, the flasks were filled up with acetone to 10 mL. The stock solutions were agitated. The measuring glass flasks containing the stock solutions prepared with acetone were closed and opened only for taking aliquots for preparation of the test concentrations.
The test concentrations were prepared by adding 0.1 mL/L of the appropriate stock solutions (see Table 2) to the dilution water (see Table 3). These solutions were stirred for 30 minutes at 1100 rpm and used for testing.

Test organisms

Test organisms (species):

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

Details on test organisms:

Test organism Pseudokirchneriella subcapitata HINDÄK, SAG 61.81
Reason for the selection of the test organism: Pseudokirchneriella subcapitata is a suitable green alga species according to the guideline.
Origin: Sammlung von Algenkulturen (SAG) Pflanzenphysiologisches Institut der Universität Göttingen Nikolausberger Weg 18, D-37073 Göttingen
Cultivation at test facility: Fresh stocks are prepared every month on Z-Agar. Light intensity amounted to 2567-5130 lux for 24 hours per day.
Culture medium: Nutrient medium Z according to Luttge et al. (1994)

Study design

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test conditions

Hardness:

The medium had a nominal hardness of 0.24 mmol Ca+Mg/L.

Test temperature:

Nominal range: 21 - 24 °C, controlled at ± 2 °C.

pH:

The pH-value at the start of exposure was measured in one additional replicate of each test item concentration and the controls. At the end of exposure, the pH-values were measured from pooled samples of each test item concentration and the controls.

Nominal and measured concentrations:

Definitive Test: Six concentrations were tested in a geometrical series with a (nominal) dilution factor of 2: 0.125 - 0.250 - 0.500 - 1.00 - 2.00 - 4.00 mg/L. The respective time-weighted average exposure concentrations determined by analysis were 0.0537, 0.104, 0.213, 0.397, 1.10 and 2.64 mg/L at the 0.125, 0.25, 0.5, 1, 2 and 4 mg/L nominal test concentrations.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2.64 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other:

Remarks:

The 72hr ErC50 was determined to be greater than the highest test concentrations tested. An extrapolation on the dose-response curve put this value at 2.69 mg/L

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.08 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.397 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.:

1.35 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other:

Remarks:

Yield

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.469 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other:

Remarks:

Yield

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.397 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other:

Remarks:

Yield

Results with reference substance (positive control):

The toxicity of potassium dichromate (Sigma, batch number MKBV0900V, purity 99.0 %, CAS RN 7778-50-9) to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined over a period of 72 hours from 2016-10-11 to 2016-10-14 (with headspace) and 2016- 10-10 to 2016-10-13 (without headspace), respectively. The reference item toxicity is in the valid range following test facility SOPs.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

All validity criteria were fulfilled during the study :
- Increase of the cell growth in the control cultures : Control : 130-fold; Solvent Control : 126-fold (criteria is > = 16-fold);
- Mean coefficients of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3) in the control cultures : Control : 18.2%; Solvent Control : 21.8% (criteria < = 35%);
- Coefficient of variation of average specific growth rates during the whole test period in replicate control cultures : Control : 1.19%; Solvent Control : 1.16% (criteria < = 7%)

In this study, DUPICAL was found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 hours with the following effect values (based on nominal test item concentrations): The EC50-values with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were > 4.00 mg/L [Extrapolated as: 4.06 (3.92 - >4.00 mg/L)] and 2.42 (2.02 - 2.88) mg/L, respectively. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 1.00 mg/L, respectively.
The EC50-values based on time weighted average test item concentrations with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were > 2.64 mg/L [Extrapolated as: 2.69 (2.57 - > 2.64) mg/L] and 1.35 (1.07 - 1.70) mg/L, respectively. The NOEC- values for both inhibition of growth rate and yield after 72 hours were 0.397 mg/L, respectively.

Executive summary:

The toxicity of DUPICAL to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 761/2009 C.3 from 2017-01-10 to 2017-01-14 with the definitive exposure phase from 2017-01-10 to 2017-01-13, at the test facility. The aim of the study was the determination of NOEC, LOEC, EC10, EC20- and EC50-values of growth rate and yield over a period of 72 hours.

A clear dose-response relationship was observed for both the yield and growth component for algae. The EC50-values based on time weighted average test item concentrations with 95 % confidence intervals for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were > 2.64 mg/L [extrapolated as: 2.69 (2.57 - > 2.64) mg/L] and 1.35 (1.07 - 1.70) mg/L, respectively. No significant effects on either the yield or growth of algal cells was observed at concentrations at and below 0.397 mg/L, based on time-weighted average test item concentration.