(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one

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:

26/03/1999 - 29/10/1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study according to Guideline under GLP, validity criteria met.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes (incl. QA statement)

Remarks:

Statement of compliance

Test material

Test material information

Constituent 1

Reference substance name:

(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one

EC Number:

201-210-7

EC Name:

(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one

Cas Number:

79-50-5

Molecular formula:

C6H10O3

IUPAC Name:

(±)-dihydro-3-hydroxy-4,4-dimethylfuran-2(3H)-one

Details on test material:

- Name of test material (as cited in study report): DL-Lactone
- Physical state: white christalline mass
- Stability under test conditions: stable
- Storage condition of test material: at room temperature in the dark

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not relevant

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

During the final test samples were taken from the blank-control and the 100 mg/l test solution for analysis.
Frequency: At t=O h, t=24 h and t=72 h
Volume: 10 ml
Storage: Not applicable, samples were analysed on the day of sampling.
Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest
substance concentration but without algae and samples for analysis were taken at the start and the end of the test period.
Additionally, reserve samples of 10 ml were taken from all test solutions and stored in a deepfreeze
until possible analysis for a maximum of three months or until delivery of the final report.
The method of analysis is described in the appended Analytical Report.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: DL-LACTONE was completely soluble at the concentrations tested. In the range-finding test,test solutions were prepared by subsequent
dilution starting with a stock solution of 100 mgll in ISO-medium. No other treatment than careful mixing was necessary to dissolve the test
substance in the test medium. For the final limit study a test solution of 100 mgll was prepared only. The final test solutions were all clear and
colourless. After preparation, volumes of 50 ml were added to each replicate of the respective test concentration.
- Controls: Yes, blank control

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: CCAP 278/4
- Age of inoculum (at test initiation): 4 days
- Method of cultivation: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar.
The suspensions were continuously aerated and exposed to light (4000-9000 lux) in a climate room at a temperature of 23 +/- 2°C.


ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): yes

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

Not relevant

Test conditions

Hardness:

24 mg CaCO3/ ml

Test temperature:

21.5 - 22.5°C

pH:

8.1 - 8.7 (Control)
7.9 - 8.5 (Test solution)

Dissolved oxygen:

No data

Salinity:

Not relevant

Nominal and measured concentrations:

Nominal: 0, 100 mg/l
Measured: -, 78 mg/l (average)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 100 ml, all-glass
- Aeration: No data
- Initial cells density: 10,000 cells/ml
- Control end cells density:
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, M2-Medium according to ISA Standard 8692.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water purified by reverse osmosis and then passed over activated carbon and ion-exchange cartridges
- Culture medium different from test medium: no
- Intervals of water quality measurement: Temperature: daily; pH: at the beginning and at the end of the test

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: Continuously, light intensity of 3500 - 4000 lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]: At the
beginning of the test, cells were counted by microscope, using a counting chamber. Thereafter cell densities were determined by spectrophotometric measurement.
- Chlorophyll measurement: spectrophotometric measurement of samples at 720 nm using a Lambda Spectrophotometer, with a cuvette of 5 cm
path-length. Algal medium was used as blank.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 78 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes/no: Yes, cell density increased by an average factor of > 16 within three days.
Analysis of samples taken from the solution without algae showed that the measured
concentration decreased from 105 mg/l to 76 mg/l during the 72-hour exposure period.
Further, all test conditions remained within the ranges prescribed by the protocol.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: The presence of an extra peak in the
chromatograms indicated that this decrease was probably related to degradation. Based on the measured
concentrations the algal suspensions had been exposed to an average measured concentration of 78 mg/l. Hence, the concentration measured
decreased just slightly more than 20% from initial during the test period. The results showed that this decrease was enhanced in the presence of
growing algae. Hence, the analytical support showed that the effect on actual concentration of the test substance was at least partly inherent to the
test design.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 0.75 mg/l

Reported statistics and error estimates:

For determination of the NOEC and the EC50 the approaches recommended in the OECD
guideline (201, adopted 7 June 1984) were used. Statistical analysis of the data was not
needed as the effects recorded were not significant (< 10%).

Any other information on results incl. tables

Not relevant

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study with Selenastrum capricornutum, DL-LACTONE induced no effect on algal growth at a concentration of
100 mg/l. The EC50 for both algal growth and growth rate exceeded a concentration of 100 mg/l (NOEC), corresponding with an average measured
concentration of 78 mgll.

Executive summary:

Selenastrum capricornutum, Fresh Water Algal Growth Inhibition Test with DL-LACTONE.

DL-LACTONE was completely soluble at the concentrations tested. After a range-finding test, a

limit test was performed exposing exponentially growing algal cultures to a DL-LACTONE

concentration of 100 mg/l and to a blank-control. The initial cell density was l0,000 cells/ml. The

total test period was 72 hours. Samples for analysis of actual exposure concentrations were

taken at the start, after 24 hours of exposure and at the end of the test period. Sampling

included a test solution prepared at 100 mg/l incubated without algal cells present.

Analysis of the samples showed that the concentrations measured at the start of the test were in

agreement with nominal. Further, the measured concentration remained above 80% relative to

the initial concentration during the first 24-hour exposure period. At the end of the 72-hour

exposure period, the concentration measured in the sample taken from the solution with algae

had decreased to 45 mg/l, whereas the concentration measured in the solution without algae

remained at 76 mg/l. The presence of an extra peak in the chromatograms indicated that this

decrease was probably related to degradation.

DL-LACTONE induced no effect on algal growth at a concentration of 100 mg/l during 72 hours

of incubation. The exposure included degradation of DL-LACTONE, which was at least partly

related with algal growth.

The EC50 for both algal growth and growth rate exceeded a concentration of 100 mg/l (NOEC),

corresponding with an average measured concentration of 78 mg/l.