Hydroxycyclohexyl phenyl ketone

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The samples were diluted with isopropanol to a total volume of 50 mL. Aliquots were filtered and used for GC-MS analysis

Vehicle:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain: SAG 86.81
- Source (laboratory, culture collection): Originally obtained from Collection of algal cultures in University of Göttingen, Germany. A stock algal culture is continuously maintained at the test facility
- Age of inoculum (at test initiation): 3 days growth

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.1 - 23.5 °C

pH:

7.9 - 8.4

Nominal and measured concentrations:

nominal: control, 0.32, 1.0, 3.2, 10 and 32 mg/L
mean measured: -, -, 0.7, 2.1, 5.9, 19.8 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks
- Material, size, headspace, fill volume: glass beaker plugged with gas permeable silicone sponge caps, 100 mL fill volume
- Initial cells density: 0.5E+04 cells/mL
- Control end cells density: 78.6E+04
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

- Light intensity and quality: average 5008 lux at a wave length of 400 - 700 nm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber; fluorimeter

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

14.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.51 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

> 19.8 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.:

4.68 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.84 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

18.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

The measured concentrations of the test substance in the test media at the start of exposure (0 hour) were >90% of the nominal concentrations. At the end of exposure (72 hour) the measured concentrations decreased to 45 – 55 % of the nominal concentrations. Samples were filtered prior to analytical determination; therefore this decrease may be due to binding of the test substance to the algal cells. To evaluate this possibility, retained samples from replicates without algal cells (uninoculated) were analyzed. The measured concentrations in the 72 hour uninoculated samples showed a similar decrease as the samples with algae, ranging from 37 – 50% of the nominal concentration. Therefore the decrease in measured concentration during the test was not due to binding of the test substance to the increasing algal biomass, but rather due to loss or instability of the test substance in the test system and under test conditions.
The test substance is known to be readily biodegradable and susceptible to photolysis (information from sponsor). For the 1.0 mg/L group only the value for the uninoculated 72-h sample was available. Since the uninoculated 72-h sample in the 1.0 mg/L test group had a similar decrease relative to the nominal concentration as the other test groups, the measured 0-h value was estimated to be 90% of the nominal concentration similar to the other test groups. This value was used to calculate a mean measured concentration in the 1.0 mg/L test group. The results of the toxicity test should be evaluated based on the mean measured concentrations calculated using the values from uninoculated replicates.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 0.82 mg/L (based on growth rate)

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the 72 hour EC50 (growth rate) of the test material was determined to be 14.4 mg/l.

Executive summary:

In this guideline (OECD 201) study conducted with GLP certification, the 72 hour EC50 (growth rate) of the test material to freshwater algae was determined to be 14.4 mg/l. The test was conducted under static conditions with test concentrations between 0.32 and 32 mg/l. The study result does not trigger classification as hazardous for the aquatic environment under the the conditions of the Classification, Labelling, and Packaging (CLP) regulation (1272/2008), as the test material is readily biodegradable and has a BCF <500.

Description of key information

Study carried out according to guideline and with GLP compliance.

Key value for chemical safety assessment

EC50 for freshwater algae:

14.4 mg/L

Additional information

The key study for the determination of the inhibition of algal growth was conducted according to OECD guideline 201 including analytical test item concentration verification (BASF SE, 2010). The ErC50 (72 h) was 14.4 mg/L based on mean measured test item concentrations. The ErC10 was determined to be 2.51 mg/L