α-hydroxy-β,β-dimethyl-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:

09.10. - 16.10.2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to guideline, under GLP

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:

2009

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:

α-hydroxy-β,β-dimethyl-γ-butyrolactone

EC Number:

209-963-3

EC Name:

α-hydroxy-β,β-dimethyl-γ-butyrolactone

Cas Number:

599-04-2

Molecular formula:

C6H10O3

IUPAC Name:

(3R)-3-hydroxy-4,4-dimethyloxolan-2-one

Constituent 2

Reference substance name:

209 963 3

IUPAC Name:

209 963 3

Details on test material:

- Name of test material (as cited in study report): R-Pantolactone
- Physical state: solid
- Storage condition of test material: RT (20°)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Water solubility (under test conditions): well soluble

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

For measurement of the actual concentrations of the test item, duplicate samples were taken from the test media of all test concentrations at the start of the test (without algae) and at the end of the test (containing algae). At the same sampling times, duplicate samples were also taken from the control.
Additional duplicate stability samples were taken from the highest test concentration of 100 mg/L after 24 and 48 hours.

At the start of the test, the concentrations of the test item R-Pantolactone were determined in the duplicate test medium samples from all nominal test concentrations and from the control. At the end of the test, the concentrations of the test item were determined in the duplicate test medium samples from the nominal test concentrations of 36 and 100 mg/L and from the control. The samples from the nominal test concentrations of 0.58 to 13 mg/L were not analyzed at the end of the study, since these concentrations were below the NOEC determined in this test.

Additionally, duplicate samples of the highest test concentration of 100 mg/L were analyzed after 24 and 48 hours of test duration to show the degradation kinetics of the test item at this concentration.

Test solutions

Vehicle:

no

Details on test solutions:

The following nominal concentrations of the test item were tested: 0.58, 1.6, 4.6, 13, 36 and 100 mg/L. Additionally, a control was tested in parallel (test water without test item).

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchnerella subcapitata
- Strain: No. 61.81 SAG
- Source (laboratory, culture collection): Collection of Algal Cultures (SAG, Institute for Plant Physiology, Göttingen)
- Age of inoculum (at test initiation): An inoculum culture was set up four days before the start of the exposure. The algae were cultivated under the test conditions.
- Method of cultivation: The inoculum culture was diluted threefold one day before the start of the test to ensure that the algae were in the exponential growth phase when used to inoculate the test solutions.

Study design

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Post exposure observation period:

not applicable

Test conditions

Hardness:

0.24 mmol/L (= 24 mg/L as CaCO3)

Test temperature:

21 - 24°C

pH:

7.9 - 8.9

Dissolved oxygen:

-

Salinity:

-

Nominal and measured concentrations:

Nominal: control, 0.58, 1.6, 4.6, 13, 36, 100 mg/L
Measured: -, - , - , - , - , 22, 63 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL labeled Erlenmeyer flasks were used per replicate containing 15 mL of test solution. Each test flask was covered with a glass dish.
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber
- Chlorophyll measurement: fluorence measurement

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 63 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.:

> 63 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.:

> 63 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:

EC10

Effect conc.:

57 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

Yield (calculated)

Effect concentrations 5

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no

Results with reference substance (positive control):

the sensitivity of the test system was within the internal historical range (72-hour EC50 for the growth rate: 1.1 mg/L, range of the 72-hour EC50 for the growth rate from 2000 to 2009: 0.71 - 1.74 mg/L).

Reported statistics and error estimates:

Growth rate and yield were calculated for each test flask. The mean values for growth rate and yield were calculated for each treatment. The tabulated values represent rounded results obtained by calculation using the exact raw data.
The 72-hour EC10, EC20 and EC50 values for the inhibition of average growth rate and yield and their 95% confidence intervals were calculated as far as possible by Probit Analysis.
For the determination of the LOEC and NOEC, average growth rate and yield at the test concentrations were compared to the control values by
Williams tests.

Any other information on results incl. tables

The measured concentrations of the test item in the test media of the test concentrations of 0.58 to 100 mg/L were between 96 and 115% of the nominal values at the start of the test. This shows the correct dosage of the test item at test start. The degradation of the test item over the testing period should be demonstrated by additional analytical determinations of the concentrations of the highest test concentration of 100 mg/L after 24 hours and 48 hours: 91 and 82% of the nominal values were measured, respectively. After 72 hours, at the two highest test concentrations of 36 and 100 mg/L, 38 and 41% of the nominal values were found, respectively.

Thus, a decrease of the test item concentration in the test media occurred over the test period of 72 hours.

 

Therefore, the biological results were related to the mean measured test item concentrations, calculated as the geometric means of the concentrations measured at the start and at the end of the test.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The test item had a statistically significant inhibitory effect on the growth of the algae (average growth rate and yield) after the test period of 72 hours at the highest concentration of 63 mg/L. Thus, this concentration was determined to be the 72 hour LOEC.

Executive summary:

 The measured concentrations of the test item in the test media of the test concentrations of 0.58 to 100 mg/L were between 96 and 115% of the nominal values at the start of the test. This shows the correct dosage of the test item at test start. The degradation of the test item over the testing period should be demonstrated by additional analytical determinations of the concentrations of the highest test concentration of 100 mg/L after 24 hours and 48 hours: 91 and 82% of the nominal values were measured, respectively. After 72 hours, at the two highest test concentrations of 36 and 100 mg/L, 38 and 41% of the nominal values were found, respectively.

Thus, a decrease of the test item concentration in the test media occurred over the test period of 72 hours.

Therefore, the biological results were related to the mean measured test item concentrations, calculated as the geometric means of the concentrations measured at the start and at the end of the test. The test item had a statistically significant inhibitory effect on the growth of the algae (average growth rate and yield) after the test period of 72 hours at the highest concentration of 63 mg/L. Thus, this concentration was determined to be the 72-hour LOEC.

The 72-hour NOEC was determined to be 22 mg/L, since up to and including this test concentration, the growth rate and yield of the algae after 72 hours were not statistically significantly lower than in the control.