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Short term toxicity on aquatic invertebrates

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the eight closest read across substances, the short term toxicity on aquatic invertebrates was predicted for 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (2345-26-8). EC50 value was estimated to be 48.05 mg/l for Daphnia magna for 48 hrs duration. Based on the value, 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (2345-26-8) was considered to be toxic to aquatic invertebrates but as it was readily biodegradable, hence it can be considered to be not classified as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3,7-dimethylocta-2,6-dien-1-yl 2-methyl propanoate (CAS no. 2345 -26 -8) (2017). EC50 value was estimated to be 48.55 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate is considered to be toxic to aquatic environment. Since the chemical is readily biodegradable in nature, chemical 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate can be considered as non-toxic to aquatic organisms and can be considered to be not classified as per the CLP classification criteria.

Additional information

Short term toxicity to aquatic invertebrates

Short term toxicity to aquatic invertebrates for 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (2345-26-8) was summaries with predicted data for target and experimental study of read across are summaries as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the eight closest read across substances, the short term toxicity on aquatic invertebrates was predicted for 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (2345-26-8). EC50 value was estimated to be 48.05 mg/l for Daphnia magna for 48 hrs duration. Based on the value, 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (2345-26-8) was considered to be toxic to aquatic invertebrates but as it was readily biodegradable in nature, hence it can be considered to be not classified as per the CLP regulations.

Study was performed according to the ISO (International Organization for Standardization) 6341 in read across Fenofibrate (49562-28-9) from Environment International 33 (2007) 635–641.The test was performed in < 24 hrs neonates, 5 daphnids per vessels were used and four replicates for each of five concentrations were taken for study. Daphnids were exposed at 20 degree C at dark and the test was performed for 24 hrs. The mobility of daphnids were observed after 24 hrs, on the basis of result, the EC 50 value for Fenofibrate (49562-28-9) was determined to be 50.12 mg/l between 44.78–58.55 mg/l concentration range. Based on the value the fenofibrate was considered to be toxic to aquatic toxicity but at it was readily biodegradable, hence it can be considered to be not classified as per the CLP regulations.

Based on the above prediction of target and studies of functional read across, it was considered that 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (2345-26-8) was non-toxic to aquatic invertebrates and can be considered to be not classified as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Predicted data for the target chemical 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate (CAS No. 2345-26-8) and various weight of evidence study for its read across substance were reviewed to summarize the following information:

 

Short term toxicity on aquatic algae and cyanobacteria of target chemical3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate(CAS No. 2345-26-8) is predicted using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances (2017). EC50 value was estimated to be 48.55 mg/l for Desmodesmus subspicatus for 72 h duration. Based on this value it can be concluded that the substance 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate is considered to be toxic to aquatic environment. Since the chemical is readily biodegradable in nature, chemical 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate can be considered as non-toxic to aquatic organisms and can be considered to be not classified as per the CLP classification criteria.

 

In a weight of evidence study from peer reviewed journal (Marina Isidori et. al, 2007) of the read across chemical Isopropyl 2 -[4 -(4 -chlorobenzoyl)phenoxy]-2 -methylpropanoate (CAS no. 49562 -28 -9), short term toxicity to Pseudokirchneriella subcapitata (green algae) study was carried out for 72 hrs. The study was performed according to ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum).The study was based on the effects of the read across compound Isopropyl 2 -[4 -(4 -chlorobenzoyl)phenoxy]-2 -methylpropanoate (CAS no. 49562 -28 -9) on green algae in a static fresh water system at a temperature of 25°C. The algal inoculum was taken from an exponentially growing pre-culture and added to 25 ml of test solution to obtain an initial cell density of the order of 104 cells/ml. Test compound was tested in five concentrations and three replicates. Flasks were placed in a growth chamber at 25 °C under 8000lux. The cell density was measured at 0 time and every 24 h for 3 days by an electronic particle dual threshold counter (Coulter Counter Z2, 100μm capillary, Instrumentation Laboratory, Miami, FL, USA). From these data the algal growth inhibition in percentage was calculated by integrating the mean values from t0 to t72 h (area under the curve). Inhibition (%) values were tabulated against log-transformed data of concentrations to evaluate the test concentration corresponding to 50% algal growth inhibition. Based on effect on growth rate of the test organism Pseudokirchneriella subcapitata, the 72 hr EC50, NOEC and LOEC value was determined to be 19.84, 3.12 and 6.25 mg/l respectively. Thus, based on the EC50 value, it can be concluded that the substance Isopropyl 2 -[4 -(4 -chlorobenzoyl)phenoxy]-2 -methylpropanoate can be considered as toxic to aquatic organisms. Since the chemical is readily biodegradable in nature, chemical Isopropyl 2 -[4 -(4 -chlorobenzoyl)phenoxy]-2 -methylpropanoate can be considered as non-toxic to aquatic organisms and thus can be considered to be not classified as per the CLP classification criteria.

 

For another read across chemical hexadec-11-en-1-yl acetate (CAS no. 34010-21-4),short term toxicity to Desmodesmus subspicatus (green algae) study was carried out for 72 hrs (Esmeralda Rosa et. al; 2006). The study was performed according to EU Method C.3 (Algal Inhibition test).The study was based on the effects of the read across compound hexadec-11-en-1-yl acetate (CAS no. 34010-21-4) on green algae in a static fresh water system at a temperature of 23±2°C under continuous white light (120µE/s/m2). Desmodesmus subspicatus (formely known as Scenesdesmus subspicatus, CCAP 276/20)was used as a test organism obtained from the Culture Collection Algae and Protozoa (Cumbria, UK).Initial cell densities were adjusted at 104 cells/ml using a calibration curve of chlorophyll absorbance (λ= 650 nm) versus cell number and appropriate dilution of pre-culture. Test chemical conc. used for the study was 1, 5, 10, 25 and 50 mg/l (nominal concentration) and 0.77, 4.13, 7.95, 24.35 and 36.66 mg/l (measured concentration), respectively. Aqueous solutions of the chemicals were prepared by adding the appropriate amounts of stocks in acetone (HPLC grade; <0.5 ml l−1) to 100 ml borosilicate flasks and allowing the acetone to evaporate. The flask was then filled with the appropriate volume of algal medium, mixed thoroughly and sonicated for 1 h. Borosilicate flasks of 100 ml was used as a test vessel for the study. Test vessel was kept in suspension by continuous shaking at 60 rpm. Algal medium was prepared according to the protocol of EEC Directive 92/69/EEC using deionized water and analytically pure chemicals. The average growth rates were calculated from cell numbers based on measurements of chlorophyll absorbance at λ= 650 nm in a dual-beam spectrophotometer (Uvikon 941) and converted to proportional responses relative to controls. Median effect concentration levels (EC50) for the chemicals were estimated from concentration–response curves, obtained considering proportional algae growth, survival and feeding responses relative to control treatments, by fitting observed responses to the non-linear allosteric decay regression model. Based on effect on growth rate of the test organism Desmodesmus subspicatus, the 72 hr EC50 value was determined to be 103.74 mg/l, respectively. Thus, based on the EC50 value, it can be concluded that the substance hexadec-11-en-1-yl acetate can be considered as non-toxic to aquatic organisms and thus can be considered to be not classified as per the CLP classification criteria.

 

Thus, based on the overall reported results for target chemical 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate (OECD QSAR toolbox version 3.3, 2017) and for its read across substance (from peer reviewed journal), it can be concluded that the test substance 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate can be considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.