α-acetyl-γ-butyrolactone

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:

2016-02-029 to 2016-04-06

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:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

(2009)

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(2006)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

α-acetyl-γ-butyrolactone

EC Number:

208-235-2

EC Name:

α-acetyl-γ-butyrolactone

Cas Number:

517-23-7

Molecular formula:

C6H8O3

IUPAC Name:

3-acetyloxolan-2-one

Constituent 2

Reference substance name:

α-acetly-ɣ-butyrolacton

IUPAC Name:

α-acetly-ɣ-butyrolacton

Test material form:

other: liquid

Details on test material:

- Purity: 97.5 % (according to data of the sponsor)
- Empirical formula: C6H8O3
- Molecular mass: 128.1 g/mole

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.88, 1.9, 4.3, 9.4, 21, 45 and 100 mg/L plus control
- Storage: Routinely, the samples were analysed immediately. Only in exceptional cases, they were stored
overnight deep frozen and protected from light.

Test solutions

Vehicle:

no

Details on test solutions:

Pre-treatment of α-acetly-ɣ-butyrolacton and preparation of α-acetly-ɣ-butyrolacton concentrations
Prior to the test the dilution water was adjusted from pH 7.9 to pH 6.0.
A stock solution was prepared to give the desired series of test concentrations. 201.0 mg of α-acetly-ɣbutyrolacton were added to 2 litres of dilution
water and stirred for 1 h on a magnetic stirrer.
The pH was measured to be 6.1.
To produce the different α-acetyl-ɣ-butyrolacton concentrations appropriate amounts of the stock solution were diluted with dilution water to a volume of 100 mL and 0.532 mL of the algal inoculum was added to each replicate resulting in a final cell density of 5000 cells/mL. For each α-acetyl-ɣ-butyrolacton concentration and the control 3 replicates were prepared. All flasks were sealed with cotton stoppers.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Test species
- Name: Desmodesmus subspicatus (formerly Scenedesmus subspicatus) Strain No. 86.81 SAG
- Source: Strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen
(Germany).
- Maintenance and Acclimatisation: Exponentially growing stock cultures were maintained in the test facility under constant temperature conditions (21-24 °C with a maximum fluctuation of +/- 2 °C) at a light intensity in the range 60 to 120 μE x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The growth medium (according to BRINGMANN & KÜHN (1977) was renewed once a week. Cell density measurements were made using a microcell counter, Sysmex F300, Digitana.
- Preparation of pre cultures: Pre cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different growth medium.
- Test cultures: The algal inocula for the test were taken from an exponentially growing pre culture and were mixed with the growth medium to make up to a final cell density of about 5000 cells per millilitre in the test medium.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

no data

Test temperature:

21 - 24 °C

pH:

Control: 6.5 at 0h and 5.0 at 72 h
Concentrations 0.88, 1.9, 4.3, 9.4, 21, 45 and 100 mg/L 6.3 -6.5 at 0 h and 4.4 -4.6 at 72 h
The pH value in α-acetyl-ɣ-butyrolacton slightly increased by more than 1.5 pH units. This increase is not regarded to by relevant to results as all valdity criteria were met.

Dissolved oxygen:

not applicable

Salinity:

not relevant

Conductivity:

not relevant

Nominal and measured concentrations:

Concentrations: 0.88, 1.9, 4.3, 9.4, 21, 45 and 100 mg/L plus control

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 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:

NOEC

Effect conc.:

4.246 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The results are expressed in terms of geometric mean measured concentrations.
Effective concentrations ranged from 96.9 % to 113.2 % of nominal values at 0 hours, from 42.0 to 76.4 % of nominal values at 24 hours, from 28.8 % to 71.7 % of nominal values at 48 hours and from 17.9 % to 73.7 % of nominal values at 72 hours.

Any other information on results incl. tables

Reduction of growth rate (ErCx, NOEC [r]) is the preferred endpoint according to OECD 201 and for regulatory purposes in the EU. Results relating to yield (EyCx, NOEC [y]) were calculated to fulfil regulatory requirements in some countries (but not in the EU) and are given in the results section of this report.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

(-The cell density in the control cultures increased by a factor > 16. -The mean of the replicatecoefficient of variation for section-by-section growth <35%. -The confficient of variation of the mean specific growth rate replicates in the control < 7 %)

Conclusions:

A 72-h growth inhibition test with the unicellular green alga Desmodesmus subspicatus was performed with the test substance 2-acetylbutyrolactone according to the OECD guideline 201 (GLP conditions). It can be concluded that the test item had no significant inhibitory effect on the growth of Desmodesmus subspicatus up to and including the test concentration of 4.246 mg/L.The geometric mean measured EC50 for growth rate inhibition (72-h ErC50) was >100 mg/L. The results of the test can be considered reliable without restriction.

Executive summary:

The toxicity of α-acetyl-ɣ-butyrolacton to algae (Desmodesmus subspicatus) was determined according to EU method C.3 ‘Freshwater Alga and Cyanobacteria, Growth inhibition test’ (2009) which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006). Exponentially growing algal cells were exposed for a period of 72 hours to range of concentrations, nominally 0.88, 1.9, 4.3, 9.4, 21, 45 and 100 mg/L of α-acetly-ɣ-butyrolacton dissolved in dilution water. The cell densities were measured at 24 hours intervals. Inhibition of the algal population was measured as reduction in growth rate [r], relative to control cultures grown und identical conditions. The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 96.9 % to 113.2 % of nominal values at 0 hours, from 42.0 to 76.4 % of nominal values at 24 hours, from 28.8 % to 71.7 % of nominal values at 48 hours and from 17.9 % to 73.7 % of nominal values at 72 hours. An ErC10 of 11.31 mg/L and an ErC50 of >100 mg/L were measured; a NOEC[r] of 4.246 mg/L and a LOEC[r] of 8.276 mg/L were calculated. This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute algae study.