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Biodegradation in water

Biodegradability of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (CAS no. 2345 -26 -8) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor (2017). Test substance undergoes 90.5% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical

3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate was estimated to be readily biodegradable in water.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound

3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate (CAS No. 2345 -26 -8). If released in to the environment, 18% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.9%), indicates that 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (CAS No. 2345 -26 -8) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 81% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Additional information

Biodegradation in water

Various predicted data for the target compound 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate(CAS No. 2345-26-8) and various supporting weight of evidence studies for its read across substances were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate(CAS No. 2345-26-8) was estimated.Test substance undergoes 90.5% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate was estimated to be readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate(CAS No. 2345-26-8) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate is expected to be readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) for the read across chemical methyl (3 -oxo-2 -pentylcyclopentyl)acetate (CAS no. 24851 -98 -7),biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance methyl (3 -oxo-2 -pentylcyclopentyl)acetate. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of read across substance was determined to be 98, 91 and 100% by BOD, TOC removal and GC parameter in 28 days. Thus, based on percentage degradation, methyl (3 -oxo-2 -pentylcyclopentyl)acetate is considered to be readily biodegradable in nature.

 

For the another read chemical 1,2-Benzenedicarboxylic acid, di-2-propenyl ester (CAS no. 131-17-9) from peer reviewed journal (Ryuichiro KURANE et. al; 1977), biodegradation study was conducted for evaluating the percentage biodegradability of read across substance 1,2-Benzenedicarboxylic acid, di-2-propenyl ester (CAS no. 131-17-9). Pseudomonas acidovorans 256-l (microorganism) was used as a test inoculum. Microorganisms were isolated from soil and waste water by enrichment shaking culture at 30°C, using DEHP as a sole carbon source. Microorganisms were purified by successive streak transfers on four kind of medium, i.e., DEHP agar, nutrient agar, Rich-agar and Poor-agar medium. After precultivation on DEHP slant agar for 2 days, three loops of cells were inoculated into 500ml flasks containing 150ml of the medium containing DEHP as a sole carbon source, and cultivated with rotary shaker at 30°C. Phthalate esters were usually extracted with n-hexane, which were extracted with chroloform), and estimated with a Shimadzu gas chromatograph (model GC-5A). The columns used were a glass column of 3.0 mm in inside diameter, 2m in length, packed with Silicone OV-17 on 60/80 mesh Uniport B or Silicone SE-52 on 60/80 mesh Uniport B.Water-soluble TOC of culture broth was estimated with a Beckman model 915 TOC analyzer after extraction with n-hexane and centrifugation at 28,000g for 30min.The percentage degradation of read across substance was determined to be 100% degradation by GC parameter in 2 days. Thus, based on percentage degradation,1,2-Benzenedicarboxylic acid, di-2-propenyl ester is considered to be readily biodegradable in nature.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 1,2-Benzenedicarboxylic acid, di-2-propenyl ester (CAS no. 131-17-9) (OECD SIDS, 2004). The study was performed according to OECD Guide-line 301 C "Ready Biodegradability: Modified MITI Test” under aerobic conditions at a temperature of 25 ± 1°C.Test inoculum activated sludge was obtained from four sewage treatment works, three rivers, one lake, and two bays in Japan. For inoculum preparation, each 500 ml of the collect fresh samples from the ten sites and 5 l of the activated sludge which have been previously used were mixed. The mixture was adjust to pH 7.0 ± 1.0 and was aerated in a fill-and-draw activated sludge vessel. Thirty minutes after stopping aeration, discard about one third of the whole volume of supernatant and add an equal volume of a solution (pH 7.0 ± 1.0) containing 0.1 % each of glucose, peptone and potassium orthophosphate, to the settled material and recommence aeration. Thus procedure was repeated one per day. Initial test substance conc. used in the study was 100 mg/l. The medium was prepared by the method described in the JIS K0102:1986 21.Suspended solids concentration used for the study was 30 mg/l. Culturing apparatus consists of closed system for measuring of oxygen demand with 300 ml culture medium bottles, CO2-absorbers, temperature controller, and respirometers. Aerobic conditions was obtained using the magnetic stirrers. All tests were performed in triplicates. Aniline was used as a reference substance for the study. Reference substance aniline undergoes 64 and 81% degradation by using BOD parameter at 7 and 14 days, respectively. The percentage degradation of test substance was determined to be in the range of 76-92% degradation by BOD and %degradation parameter in 28 days. Thus, based on percentage degradation,1,2-Benzenedicarboxylic acid, di-2-propenyl ester is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (CAS No. 2345-26-8) (from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, 2017, peer reviewed journal and secondary source OECD SIDS, 2004), it can be concluded that the test substance 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate can be expected to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound

3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate (CAS No. 2345 -26 -8). If released in to the environment, 18% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.9%), indicates that 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate is not persistent in sediment.

 

Biodegradation in soil

The half-life period of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate (CAS No. 2345 -26 -8) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 81% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

On the basis of available information, the test substance 3,7 -dimethylocta-2,6 -dien-1 -yl 2 -methylpropanoate can be considered to be readily biodegradable in nature.