2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-11-29 to 2003-01-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted 1984

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

adopted 1992

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: in all test medium samples from both sampling times (0 and 72 hours); duplicate
- Sampling method: no data
- Sample storage conditions before analysis: All samples were deep-frozen (at about -20 °C) immediately after sampling

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: preparing of five individual mixtures by mixing and by ultrasonic treatment for 15 minutes and intense stirring for 96 hours
- Eluate: test water
- Differential loading: 1.0, 3.2, 10, 32, and 100 mg/L
- Control: yes

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Scenedesmus subspicatus CHODAT
- Strain: 86.81 SAG
- Source: Sammlung von Algenkulturen Gottingen
- Method of cultivation: under standardized conditions

ACCLIMATION
- Culturing media and conditions (same as test or not): under standardized conditions according to the test guidelines

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

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

Test temperature:

22 °C

pH:

7.9 (start); 7.9 and 8.1 (end)

Nominal and measured concentrations:

- loading rate: 1.0, 3.2, 10, 32, 100 mg/L
- mean measured concentration: 0.53, 1.5, 2.6, 2.3, 3.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL Erlenmeyer flasks
- Type (delete if not applicable): closed
- Aeration: no aeration
- Initial cells density: 10,000 algal cells per mL test medium
- Control end cells density: 63.80 cell number x 10,000/mL
- No. of organisms per vessel: 15 mL algal suspension for each replicate ( 10,000 algal cells per mL test medium)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6


GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tested in synthetic test water, prepared according to the test guidelines
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH (start and end); temperature and appearance of the test media: daily

OTHER TEST CONDITIONS
- Light intensity and quality: about 8500 Lux (mean value), range: 7890 to 9150 Lux


TEST CONCENTRATIONS
- Spacing factor for test concentrations: The loading rates were based on the results of a range-finding test and on the results of pre-experiments to the solubility of the test item (without GLP). However, loading rates above 100 mg/L were not tested according to the guidelines. The enlarged spacing factor of 3.2 between the loading rates was chosen according to the results of the range-finding test.
- Range finding study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate is tested as a positive control at least once per year

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.53 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

1.5 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 3 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

other: loading rate

Basis for effect:

other: growth rate and biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Colour differences: No remarkable observations were made concerning the appearance of test media.

The 72-hour NOEC was determined to be at the loading rate of 1.0 mg/L (mean measured 0.53 mg/L). The observed inhibition of 5 % compared to the control was considered to be within the normal range of biological variations and was not considered to be a toxic effect caused by the test item.

The 72-hour LOEC was determined to be at the loading rate of 3.2 mg/L (mean measured 1.5 mg/L) since the growth was statistically significanfiy reduced at this loading rate and above (results of Dunnett-tests, one-sided, a = 0.05).

The EC50-values for the algal biomass (b) and the growth rate (r) after 72 hours test durafion could not be determined since the inhibition of growth was at the loading rates of 3.2 to 100 mg/L below 50%. At the loading rates of 10 to 100 mg/L, the inhibition of growth rate was about 10 to 13% and the inhibifion of biomass amounted to about 30 to 38%. The EC50 for growth rate and biomasse was estimated to be higher than 3 mg/L on the basis of mean measured concentrations of the test item.

The microscopic examination of the algal cells after 72 hours test period showed no difference between the algae growing in the WAF with the loading rate of 32 mg/L and the algal cells in the control. The shape and size of the algal cells growing in test media containing the test item at up to this test concentrafion were obviously not affected. In the control, the cell density has increased from nominal N = 1 x 10⁴ cells/mL at the start of the test (0 hours) to N = 64 x 10⁴ cells/mL (mean value) after 72 hours. Thus, the algal growth in the control was sufficienfiy high under the test condifions and the validity criterion of increase of cell density by at least a factor of 16 over the duration of the study was fulfilled.

No remarkable observations were made concerning the appearance of test media. The test media of all test concentrafions remained clear throughout the entire test period.

Validity criteria fulfilled:

yes

Conclusions:

The test substance is with high probability not acutely harmful to aquatic algae.

Executive summary:

In this guidleine (OECD 201) study conducted with GLP certification, the 72 hour EC50 of the test material (EC 444-860-9) to algae (Desmodesmus subspicatus) was estimated to be >3.0 mg/l. The test was conducted in freshwater, static, conditions. Test concentrations ranged from 1 to 100 mg/l (nominal). As the 72 hour EC50 is above 1.0 mg/l, this result does not trigger classification of the test material as hazardous to the aquatic environment according to CLP 1272/2008.

Description of key information

Study conducted to recognised testing guidelines with GLP certification.

Key value for chemical safety assessment

EC50 for freshwater algae:

3 mg/L

Additional information

The effects of the test substance on algae were investigated in a GLP-study according to OECD guideline 201. Since the test item contains two different isomers, five WAFs (water accommodated fractions) with loading rates of 1.0, 3.2, 10, 32, and 100 mg/L were used. The test was performed under static conditions using Scenedesmus subspicatus as test species and the test concentration were analytically measured at the beginning and at the end of the test (sum of both isomers). The test item concentrations decreased during the test duration of 72 h. This decrease was considered to be due to photolytical degradation of the test item due to the intensive irradiation.

Based on growth rate an EC50 (72 h) > 100 mg/L loading rate (> 3 mg/L mean measured) was reported. Additionally, an NOEC (72 h) = 1 mg/L loading rate (= 0.53 mg/L mean measured) was determined (RCC Ltd., 2003). The test substance is with high probability not acutely harmful to aquatic algae.