1,3,5-triisopropylbenzene

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:

Mar 5, 2015 to Jun 17, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

2006

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2009

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No. of test material: Batch No. 6F11027000
- Expiration date of the lot/batch: 17. Nov. 2017 (two years after first opening)
- Purity: 96 %

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 100 mg/L

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A saturated solution was prepared be adding 117 µl/L test item (eq. to 100 mg/L) to corresponding amount of algal medium and stirring slowly for 23.5 hrs.
- Eluate: The lower phase of the resulting solution was used as the test solution

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green alga
- Strain: SAG strain number 86.81
- Source: MBM Sci-encebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen)
- Method of cultivation: Algae kept as stock culture on solid agar @ 7 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.

ACCLIMATION
- Acclimation period: 4-d prior to start of each test, an aliquot of the permanent culture was brought into pre-culture medium and incubated under continuous lighting for 96 hours. The resulting culture grew exponentially.
- Culturing media and conditions: Before usage, the pre-culture was checked for the absence of cell aggregates and the cell number of culture was determined via photometric measurement.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

20.3 – 22.4 °C

pH:

pH was adjusted to 7.0 (± 0.2)

Nominal and measured concentrations:

100 mg/L (nominal); 0.06 mg/L (geometric mean measured)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks, total volume 65 mL
- Type: closed
- Material, size, headspace, fill volume: test vessels complete filled
- Initial cells density: 5.39 * 10³ cells/mL
- Control end cells density: 5.39 * 10³ cells/m
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6 initially The 3rd replicate of the controls was not used for evaluation of the results due to clouded cells. Considered uncritical since algal growth in the other 5 replicates was in the normal range.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: To avoid a strong pH increase and CO2 shortage in the closed system, additional 6 mL sodium hydrogen carbonate solution (50 g/L) was added to 900 mL nutrient medium. Then, pH was adjusted to 7.0 (± 0.2) and the solution was filled up to 1000 mL.
- Lighting: 5300 Lux

EFFECT PARAMETERS MEASURED :
- Determination of cell concentrations: cell number was calculated based on the determination of the absorption at 440 nm at 0, 24, 48, and 72 hours
- treatments were examined microscopically in order to assess the appearance of the algae and detect abnormalities at the end of the study

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.06 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.06 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.06 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.06 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Results with reference substance (positive control):

The EC50s of potassium dichromate were determined in a separate reference test (GLP study no. 14070902R301).
For the estimation of the EC50s of the positive control, the fits showed sufficient statistical correspondence of the data with the dose-response-equation. The values were within the normal range of the laboratory.

- During validation, the test item showed sufficient stability in closed glass flasks (92 % recovery of the measured start concentration)

- In the algae study, the recovery after 72 hours only 7 % of the measured start concentration.

- Concluded concentration of dissolved test item was affected by the presence of the test organism and dissolved test item was adsorbed or ingested by the algae.

- Determination of the biological results thus based on the geometric mean of the measured concentration.

- For calculation of measured concentration, tenfold enrichment and a recovery rate from daphnia test medium of 71% taken into account

Summary of validation criteria results:

Parameter: Increase factor biomass factor

Validity criteria :16 in 72 h

Observed value: 51         

Assessment: Valid

 

Parameter: Mean coefficient of variation of daily growth rates   

Validity criteria: max. 35%           

Observed value: 14%     

Assessment: Valid

 

Parameter: Coefficient of variation of average growth rate during the whole test period 

Validity criteria: max. 7%              

Observed value: 7%       

Assessment: Valid

Validity criteria fulfilled:

yes

Conclusions:

The study was performed as a limit test at the concentration containing 100 mg/L nominal concentration. Incubation time (test system Desmodesmus subspicatus) was 72 hours. Under these test conditions, the EC10 and EC50 of the growth rate was determined to be > 0.06 mg/L. These results were based on the geometric mean of the measured concentrations.

Executive summary:

The acute toxicity of 1,3,5-triisopropylbenzene was tested under static conditions in a 72-hour algae growth inhibition study with on the Desmodesmus subspicatus in a limit test according to OECD TG 201. Based on nominal concentrations, the 72-h EC10 was determined to be > 100 mg/L.

Description of key information

The acute toxicity of 1,3,5-triisopropylbenzene was tested under static conditions in a 72-hour algae growth inhibition study with on the Desmodesmus subspicatus in a limit test according to OECD TG 201. Based on nominal concentrations, the 72-h EC10 was determined to be > 100 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L