3,7-dimethyl-1-octyl acetate

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:

data from handbook or collection of data

Justification for type of information:

Data is from peer reviewed journal and modelling database

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Estimation of 96 hrs EC50 value of test chemical on green algae.

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

other: green algae

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Reference substance (positive control):

not specified

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1.026 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

not specified

Conclusions:

Based on effect of test chemical on the growth rate of the test organism, the 96 hrs EC50 was estimated to be 1.026 mg/l.

Executive summary:

The 96 hrs EC50 value of test chemical on green algae was estimated using the ECOSAR model.On the basis of the effect of test chemical on the growth rate of the test organism green algae, the 96 hrs EC50 was estimated to be 1.026 mg/l.Thus, based on the EC50 value, chemical can be considered as toxic to aquatic organisms. Since the test chemical is readily biodegradable in water, test chemical can be considered as non-toxic to aq. organisms and thus can be considered to be not classified as per CLP classification criteria.

Description of key information

The 96 hrs EC50 value of test chemical on green algae was estimated using the ECOSAR model (from peer reviewed journal A.M. Api et. al., 2017 and modelling databases, 2018). On the basis of the effect of test chemical on the growth rate of the test organism green algae, the 96 hrs EC50 was estimated to be 1.026 mg/l.Thus, based on the EC50 value, chemical can be considered as toxic to aquatic organisms. Since the test chemical is readily biodegradable in water, test chemical can be considered as non-toxic to aq. organisms and thus can be considered to be not classified as per CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.026 mg/L

Additional information

Predicted data of the test chemical and various supporting weight of evidence studies for its structurally similar read across chemical were reviewed for the toxicity to aquatic algae end point which are summarized as below:

 

In a weight of evidence study from peer reviewed journal (A.M. Api et. al., 2017) and modelling database (2018), the 96 hrs EC50 value of test chemical on green algae was estimated using the ECOSAR model. On the basis of the effect of test chemical on the growth rate of the test organism green algae, the 96 hrs EC50 was estimated to be 1.026 mg/l.

 

In a supporting weight of evidence study from study report (2017), an acute test was conducted for 48 hrs for assessing the effect of test chemical on Desmodesmus subspicatus. The test was performed in accordance to OECD Guideline 201 (Alga, Growth Inhibition Test). Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) of strain 86.81 SAG obtained from Institute of botany of the ASCR with an initial biomass conc. 5x10(3) cells /ml was used as a test organism for the study. The stock solution 100 mg/l was prepared by dissolving colourless liquid in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with the OECD growth medium and inoculum culture. Nominal test chemical conc. used for the study were 12, 20, 34, 58 and 100 mg/l, respectively. Study was performed using Desmodesmus subspicatus as a test organism in a static fresh water system. Desmodesmus subspicatus were exposed to test chemical in 50 ml glass vessel in a volume of 15 ml of liquid solution containing both the chemical and media. The beakers were placed in a room at a temperature of 23±2°C, pH 7.9 with a continuous light intensity of 6000-8000 lx, respectively. Alongwith the test chemical, one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 was calculated using nonlinear regression by the software Prism 4.0. On the basis of the effect of test chemical on the growth rate of the test organism Desmodesmus subspicatus, the 72 hr ErC50 value was determined to be 53.5 mg/l with a 95% confidence interval value ranging from 46.9 to 61.1 mg/l, respectively.

 

For the test chemical from peer reviewed journal (G. BRINGMANN et. al., 1980), short term toxicity to Scenedesmus quadricauda study was carried out for 7 days. The study was based on the effects of the test chemical on Scenedesmus quadricauda in a static fresh water system at a temperature of 27ᵒC and under a constant lightning by luminescent worm white tubes at 60 cm distance from each other. Test chemical of known concentration was prepared in sterile double distilled water. Composition of test medium contains sodium nitrate (496 mg), dipotassium hydrogen phosphate (39 mg), magnesium chloride (75 mg), sodium metasilicate (40 mg), sodium carbonate (58 mg), citric acid (3 mg), iron (III) citrate (3 mg) and disodium salt of ethylene diamine tetra acetic acid (10 mg), respectively. For maintenance of the test strain of Scenedesmus quadricauda, prepare fresh stock cultures continuously at 10days intervals. For this purpose sterilize the required number of Erlenmeyer flasks* containing 20 ml of nutrient solution I and stoppered with metal caps in a steam sterilizer for 30 min each on two consecutive days. When cool inoculate the contents of each flask with 2mi cell suspension from a 10-day stock culture. Prepare dilution series in 100-ml Erlenmeyer flasks stoppered with metal caps. The dilutions will contain 1 part v/v each of pollutant solution in 20 to 214 parts v/v of mixture. Test vessel contain the known conc. of chemical and test organism. Following inoculation, at the end of 7 day, measure the extinction value of the monochromatic radiation at 578 nm in a 10 mm layer of the cell suspension from each test culture. Pollutant concentrations at which the onset of inhibitory action was observed have been obtained by mathematical evaluation. For mathematical evaluation by means of a suitable electronic calculator (a) (highest non-toxic pollutant concentration) is plotted against (A) and (b) (lowest toxic pollutant concentration) against (B) as coordinates. After entering (A - 3%), the pollutant concentration at which the inhibitory action (c) begins may be obtained from the regression line between (a;A) and(b;B)if a negative deviation of the mean extinction by a 3% difference against the mean extinction value for all test cultures having a non-toxic and non-stimulating pollutant concentration is used as an indicator of the beginning of inhibitory action. For test chemical, based on effect on growth rate of the test organism Scenedesmus quadricauda, the 7 d EC50 value was determined to be > 21 mg/l.

 

On the basis of the above results, it can be concluded that the test chemical can be considered as toxic to aquatic algae and cyanobacteria. Since the test chemical is readily biodegradable in water, test chemical can be considered as non-toxic to aquatic algae and thus can be considered to be not classified as per CLP classification criteria.