Isopentyl phenylacetate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

Data is from accepted calculation method

Qualifier:

according to guideline

Guideline:

other: Modeling database

Principles of method if other than guideline:

Determination of estimated 72 hrs EC50 value of test substance on Pseudokirchneriella subcapitata by three different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database. It is a continuous (Q)SAR model based on structural features and numeric molecular descriptors.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Selenastrum Capricornutum

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

11.79 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Domain applicability - Battery : IN

Table: Table showing the Pseudokirchneriella subcapitata 72 hr EC50 values estimated by two different models i.e, Leadscope and SciQSAR & the average EC50 value was given by the third model i.e, Battery model.

DK	Battery	Leadscope	SciQSAR
Pseudokirchneriella subcapitata 72 hr EC50 (mg/l)
Domain	IN

 

Where,

IN = inside applicability domain

Validity criteria fulfilled:

not specified

Conclusions:

Based on inhibition of growth rate of Pseudokirchneriella subcapitata, the estimated 72 hrs EC50 value by three different model i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database was evaluated to be 11.79 mg/l.

Executive summary:

Based on the prediction done using the three different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database, the short term toxicity on green algae was predicted for test substance. The average EC50 value was given by the third model i.e, Battery model. On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 11.79 mg/l for Pseudokirchneriella subcapitata during 72 hr exposure duration. Thus, on the basis of EC50 value, it can be concluded that the test chemical can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

Description of key information

Based on the prediction done using the three different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database, the short term toxicity on green algae was predicted for test substance. The average EC50 value was given by the third model i.e, Battery model. On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 11.79 mg/l for Pseudokirchneriella subcapitata during 72 hr exposure duration. Thus, on the basis of EC50 value, it can be concluded that the test chemical can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

11.79 mg/L

Additional information

Various studies available for the test chemical and structurally and functionally similar read across chemical were reviewed to determine the toxic nature of test chemical on the growth and other behavioral activity of algae and cyanobacteria. The studies are as mentioned below:

 

Based on the prediction done using the three different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database, the short term toxicity on green algae was predicted for test substance. The average EC50 value was given by the third model i.e, Battery model. On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 11.79 mg/l for Pseudokirchneriella subcapitata during 72 hr exposure duration. Thus, on the basis of EC50 value, it can be concluded that the test chemical can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Above data further supported by the second study from experimental source. Aim of this study was to evaluate the nature of test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The stock solution 100.0 mg/ml was prepared in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 0, 0, 5, 7, 11, 16.5, 25 mg/l nominal concentration were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. The median effective concentration (EC50) for the test substance, in algae was determined to be 13.4 mg/L with 95% CI: 12.5 -14.4 on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, which indicates that the substance is likely to be hazardous to aquatic algae and can be classified in chronic 3 category as per the CLP classification criteria.

 

Principle of the third study was to evaluate the nature of test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 10, 14, 20, 27.4, 38.4 mg/l concentration were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. The median effective concentration (EC50) of the test substance on algae was measured to be 23.6 mg/L with 95% CI: 21.3 -26.1 on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, which indicates that the substance is likely to be hazardous to aquatic algae and can be consider to be classified as aquatic chronic 3 category.

 

Similarly in the fourth weight of evidence study from experimental report, freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance to OECD Guideline 201. Concentration of test chemical used for the study was 0, 6.25, 12.5, 25, 50 and 100 mg/L, respectively prepared in acetone. The test was performed under static conditions at a temp. of 23±2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance in Desmodesmus subspicatus was observed to be 34.5 mg/L on the basis of effects on growth rate in a 72 hour study. Thus based on this value, test chemical can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.

 

Thus based on the above studies and effects observations on the growth of aquatic algae due to the chemical exposure for 72 hours, chemical consider to be toxic and classified in aquatic chronic 3 category as per the CLP classification criteria.