Methyl non-2-enoate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: screening tests

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

The supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Principles of method if other than guideline:

The data is predicted using the OECD QSAR toolbox version 3.3 with logKow as the primary descriptor.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material: methyl (2E)-non-2-enoate
- Molecular formula: C10H18O2
- Molecular weight: 170.25 g/mol
- Smiles notation: C(\C=C\C(OC)=O)CCCCC
- InChl: 1S/C10H18O2/c1-3-4-5-6-7-8-9-10(11)12-2/h8-9H,3-7H2,1-2H3/b9-8+
- Substance type: Organic
- Physical state: Liquid

Oxygen conditions:

aerobic

Inoculum or test system:

other: Microorganisms

Duration of test (contact time):

28 d

Based on:

not specified

Parameter followed for biodegradation estimation:

other: BOD

Key result

Parameter:

other: BOD

Value:

82

Sampling time:

28 d

Remarks on result:

other: Other details not known

Details on results:

Test substance undergoes 82% degradation by BOD in 28 days.

The prediction was based on dataset comprised from the following descriptors: BOD
Estimation method: Takes average value from the 6 nearest neighbours
Domain  logical expression:Result: In Domain

(((((((((("a" or "b" or "c" or "d" or "e" )  or "f" or "g" or "h" )  and ("i" and ( not "j") )  )  and ("k" and ( not "l") )  )  and "m" )  and "n" )  and "o" )  and "p" )  and "q" )  and ("r" and "s" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Esters (Acute toxicity) by US-EPA New Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Michael addition AND Michael addition >> Polarised Alkenes-Michael addition AND Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated esters by DNA binding by OECD

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as High reactive AND High reactive >> alpha,beta-carbonyl compounds with polarized multiple bonds by DPRA Cysteine peptide depletion

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Michael Addition AND Michael Addition >> Michael addition on conjugated systems with electron withdrawing group AND Michael Addition >> Michael addition on conjugated systems with electron withdrawing group >> alpha,beta-Carbonyl compounds with polarized double bonds  by Protein binding by OASIS v1.3

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Michael addition AND Michael addition >> Polarised Alkenes AND Michael addition >> Polarised Alkenes >> Polarised alkene - esters by Protein binding by OECD

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Class 3 (unspecific reactivity) by Acute aquatic toxicity classification by Verhaar (Modified)

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Esters by Acute aquatic toxicity MOA by OASIS

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Esters by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.3

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >>  Michael-type addition, quinoid structures OR AN2 >>  Michael-type addition, quinoid structures >> Quinoneimines OR AN2 >>  Michael-type addition, quinoid structures >> Quinones OR AN2 >> Michael-type addition on alpha, beta-unsaturated carbonyl compounds OR AN2 >> Michael-type addition on alpha, beta-unsaturated carbonyl compounds >> Four- and Five-Membered Lactones OR AN2 >> Nucleophilic addition to alpha, beta-unsaturated carbonyl compounds OR AN2 >> Nucleophilic addition to alpha, beta-unsaturated carbonyl compounds >> alpha, beta-Unsaturated Aldehydes OR AN2 >> Schiff base formation OR AN2 >> Schiff base formation >> alpha, beta-Unsaturated Aldehydes OR AN2 >> Schiff base formation >> Polarized Haloalkene Derivatives OR AN2 >> Schiff base formation by aldehyde formed after metabolic activation OR AN2 >> Schiff base formation by aldehyde formed after metabolic activation >> Geminal Polyhaloalkane Derivatives OR AN2 >> Shiff base formation after aldehyde release OR AN2 >> Shiff base formation after aldehyde release >> Specific Acetate Esters OR AN2 >> Shiff base formation for aldehydes OR AN2 >> Shiff base formation for aldehydes >> Geminal Polyhaloalkane Derivatives OR AN2 >> Shiff base formation for aldehydes >> Haloalkane Derivatives with Labile Halogen OR AN2 >> Thioacylation via nucleophilic addition after cysteine-mediated thioketene formation OR AN2 >> Thioacylation via nucleophilic addition after cysteine-mediated thioketene formation >> Haloalkenes with Electron-Withdrawing Groups OR AN2 >> Thioacylation via nucleophilic addition after cysteine-mediated thioketene formation >> Polarized Haloalkene Derivatives OR Non-covalent interaction OR Non-covalent interaction >> DNA intercalation OR Non-covalent interaction >> DNA intercalation >> Amino Anthraquinones OR Non-covalent interaction >> DNA intercalation >> Coumarins OR Non-covalent interaction >> DNA intercalation >> DNA Intercalators with Carboxamide Side Chain OR Non-covalent interaction >> DNA intercalation >> Fused-Ring Nitroaromatics OR Non-covalent interaction >> DNA intercalation >> Quinones OR Radical OR Radical >> Generation of reactive oxygen species OR Radical >> Generation of reactive oxygen species >> Thiols OR Radical >> Generation of ROS by glutathione depletion (indirect) OR Radical >> Generation of ROS by glutathione depletion (indirect) >> Haloalkanes Containing Heteroatom OR Radical >> Radical mechanism by ROS formation OR Radical >> Radical mechanism by ROS formation >> Polynitroarenes OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Amino Anthraquinones OR Radical >> Radical mechanism via ROS formation (indirect) >> Coumarins OR Radical >> Radical mechanism via ROS formation (indirect) >> Fused-Ring Nitroaromatics OR Radical >> Radical mechanism via ROS formation (indirect) >> Geminal Polyhaloalkane Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> Hydrazine Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitro Azoarenes OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitroaniline Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitroarenes with Other Active Groups OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitrophenols, Nitrophenyl Ethers and Nitrobenzoic Acids OR Radical >> Radical mechanism via ROS formation (indirect) >> p-Substituted Mononitrobenzenes OR Radical >> Radical mechanism via ROS formation (indirect) >> Quinones OR Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines OR Radical >> ROS formation after GSH depletion (indirect) OR Radical >> ROS formation after GSH depletion (indirect) >> Quinoneimines OR SN1 OR SN1 >> Nucleophilic attack after carbenium ion formation OR SN1 >> Nucleophilic attack after carbenium ion formation >> N-Nitroso Compounds OR SN1 >> Nucleophilic attack after carbenium ion formation >> Specific Acetate Esters OR SN1 >> Nucleophilic attack after diazonium or carbenium ion formation OR SN1 >> Nucleophilic attack after diazonium or carbenium ion formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Amino Anthraquinones OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines OR SN1 >> Nucleophilic attack after nitrenium and/or carbenium ion formation OR SN1 >> Nucleophilic attack after nitrenium and/or carbenium ion formation >> N-Nitroso Compounds OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Fused-Ring Nitroaromatics OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitro Azoarenes OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitroaniline Derivatives OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitrophenols, Nitrophenyl Ethers and Nitrobenzoic Acids OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Polynitroarenes OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> p-Substituted Mononitrobenzenes OR SN2 OR SN2 >> Acylation OR SN2 >> Acylation >> Specific Acetate Esters OR SN2 >> Acylation involving a leaving group  OR SN2 >> Acylation involving a leaving group  >> Geminal Polyhaloalkane Derivatives OR SN2 >> Acylation involving a leaving group  >> Haloalkane Derivatives with Labile Halogen OR SN2 >> Acylation involving a leaving group after metabolic activation OR SN2 >> Acylation involving a leaving group after metabolic activation >> Geminal Polyhaloalkane Derivatives OR SN2 >> Alkylation, direct acting epoxides and related OR SN2 >> Alkylation, direct acting epoxides and related >> Epoxides and Aziridines OR SN2 >> Alkylation, direct acting epoxides and related after P450-mediated metabolic activation OR SN2 >> Alkylation, direct acting epoxides and related after P450-mediated metabolic activation >> Haloalkenes with Electron-Withdrawing Groups OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom >> Haloalkane Derivatives with Labile Halogen OR SN2 >> Alkylation, nucleophilic substitution at sp3-carbon atom >> Sulfonates and Sulfates OR SN2 >> Alkylation, ring opening SN2 reaction OR SN2 >> Alkylation, ring opening SN2 reaction >> Four- and Five-Membered Lactones OR SN2 >> Direct acting epoxides formed after metabolic activation OR SN2 >> Direct acting epoxides formed after metabolic activation >> Coumarins OR SN2 >> Direct acylation involving a leaving group OR SN2 >> Direct acylation involving a leaving group >> Acyl Halides OR SN2 >> DNA alkylation OR SN2 >> DNA alkylation >> Alkylphosphates, Alkylthiophosphates and Alkylphosphonates OR SN2 >> DNA alkylation >> Vicinal Dihaloalkanes OR SN2 >> Internal SN2 reaction with aziridinium and/or cyclic sulfonium ion formation (enzymatic) OR SN2 >> Internal SN2 reaction with aziridinium and/or cyclic sulfonium ion formation (enzymatic) >> Vicinal Dihaloalkanes OR SN2 >> Nucleophilic substitution at sp3 Carbon atom OR SN2 >> Nucleophilic substitution at sp3 Carbon atom >> Haloalkanes Containing Heteroatom OR SN2 >> Nucleophilic substitution at sp3 Carbon atom >> Specific Acetate Esters OR SN2 >> Nucleophilic substitution at sp3 carbon atom after thiol (glutathione) conjugation OR SN2 >> Nucleophilic substitution at sp3 carbon atom after thiol (glutathione) conjugation >> Geminal Polyhaloalkane Derivatives OR SN2 >> Ring opening SN2 reaction OR SN2 >> Ring opening SN2 reaction >> Sultones OR SN2 >> SN2 at sp3 and activated sp2 carbon atom OR SN2 >> SN2 at sp3 and activated sp2 carbon atom >> Polarized Haloalkene Derivatives OR SN2 >> SN2 attack on activated carbon Csp3 or Csp2 OR SN2 >> SN2 attack on activated carbon Csp3 or Csp2 >> Nitroarenes with Other Active Groups by DNA binding by OASIS v.1.3

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Michael addition AND Michael addition >> Polarised Alkenes-Michael addition AND Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated esters by DNA binding by OECD

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Isocyanates and Isothiocyanates OR Acylation >> Isocyanates and Isothiocyanates >> Isocyanates OR Acylation >> Isocyanates and Isothiocyanates >> Isothiocyanates OR Acylation >> P450 Mediated Activation to Acyl Halides OR Acylation >> P450 Mediated Activation to Acyl Halides >> 1,1-Dihaloalkanes OR Michael addition >> P450 Mediated Activation of Heterocyclic Ring Systems OR Michael addition >> P450 Mediated Activation of Heterocyclic Ring Systems >> Furans OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Alkyl phenols OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Arenes OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Hydroquinones OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Methylenedioxyphenyl OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated amides OR No alert found OR Schiff base formers OR Schiff base formers >> Direct Acting Schiff Base Formers OR Schiff base formers >> Direct Acting Schiff Base Formers >> Mono aldehydes OR SN1 OR SN1 >> Carbenium Ion Formation OR SN1 >> Carbenium Ion Formation >> Allyl benzenes OR SN1 >> Iminium Ion Formation OR SN1 >> Iminium Ion Formation >> Aliphatic tertiary amines OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Aromatic nitro OR SN1 >> Nitrenium Ion formation >> Primary (unsaturated) heterocyclic amine OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine OR SN2 OR SN2 >> SN2 at an sp3 Carbon atom OR SN2 >> SN2 at an sp3 Carbon atom >> Aliphatic halides by DNA binding by OECD

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 7) ONLY

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 6) ONLY

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Bioavailable by Lipinski Rule Oasis ONLY

Domain logical expression index: "p"

Similarity boundary:Target: CCCCCCC=CC(=O)OC
Threshold=20%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "q"

Similarity boundary:Target: CCCCCCC=CC(=O)OC
Threshold=50%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "r"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 116 Da

Domain logical expression index: "s"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 172 Da

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

The test chemical methyl (2E)-non-2-enoate was estimated to be readily biodegradable in water.

Executive summary:

Biodegradability of methyl (2E)-non-2-enoate (CAS no. 111 -79 -5) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 82% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical methyl (2E)-non-2-enoate was estimated to be readily biodegradable in water.

Description of key information

Biodegradability of methyl (2E)-non-2-enoate (CAS no. 111 -79 -5) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 82% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical methyl (2E)-non-2-enoate was estimated to be readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Various predicted data for the target compound methyl (2E)-non-2-enoate (CAS No. 111-79-5) and supporting weight of evidence studies for its read across substance 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 chemicalmethyl (2E)-non-2-enoate(CAS No. 111-79-5) was estimated.Test substance undergoes 82% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical methyl (2E)-non-2-enoate 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 compoundmethyl (2E)-non-2-enoate(CAS No. 111-79-5) 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 methyl (2E)-non-2-enoate is expected to be readily biodegradable.

 

In a supporting weight of evidence study from peer reviewed journal (Alfredo A. Marchetti et. al, 2003) for the read across chemical 1,4-dibutyl (2Z)-but-2-enedioate (CAS no. 105-76-0),biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance1,4-dibutyl (2Z)-but-2-enedioate. The study was performed according to EPA OPPTS 835.3110 (Ready Biodegradability) and EPA OPPTS 835.3120 (Sealed Vessel Carbon Dioxide Production Test), respectively under aerobic conditions. Aerobic sludge was used as a test inoculum obtained from a municipal wastewater treatment facility in Livermore, CA. Initial test chemical concentration used for the study was50 ng/µl. Microcosms were prepared in 250-ml amber glass bottles fitted with Mininert valves (Supelco, Bellefonte, PA) and consisted of 20 ml of fresh aerobic sludge filtered using Whatman No.1 paper (Whatman Inc., Clifton, NJ), 20 ml of water, and 60 ml of nutrient medium with the following composition: KH2PO4, 85.0 mg/l; K2HPO4, 217.5 mg/l; Na2HPO4.2H2O, 33.4 mg/l; NH4Cl, 0.5 mg/l; CaCl2, 27.5 mg/l; MgSO4.7H2O, 22.5 mg/l; FeCl3.6H2O, 0.25 mg/l. Preparation of the nutrient solution was carried out as that described in the US EPA Ready Biodegradability Method. Abiotic microcosms were autoclaved twice, and sodium azide was added to produce a final concentration of 0.05%.On day 0, the microcosm bottles were purged with CO2-free air obtained by scrubbing air with a saturated NaOH solution. Test compounds were then added in 5-µlinjections using a precision syringe. Microcosms were incubated at 30°C and shaken in a Psychotherm controlled-environment shaker. Active microcosms were prepared in triplicate, and abiotic ones in duplicate. Control microcosms without test compounds were also prepared to determine background production of CO2.Benzene was used as a reference substance for the study.CO2 and test compound measurements were performed on days 0, 3, 6, 8, 10, 15, 20, and 28, respectively. Carbon dioxide was measured as methane in a gas chromatograph model 8610c equipped with a methanizer, a 15-cm silica gel column, and a flame ionization detector (FID). Samples of 1 ml of microcosm headspace were drawn for CO2 measurement; 1 ml of oxygen was injected to replace the extracted air. Samples were introduced in the chromatograph through a 250-µl injection loop after the loop was purged with the 1-ml headspace sample. To keep abiotic microcosms sterile, needles were wiped with 70% ethanol before insertion through the valve septum. Calibrations were made using commercially prepared mixtures of 0.369, 1.010, and 20.010 parts per thousand by volume (pptv) of CO2 in air.Test chemical was measured in the liquid phase. Samples of 200µl were taken from the liquid phase of the microcosms using a syringe. These were centrifuged to remove particulates and aliquots of 2–10µl were analyzed using a Micro-Tech Ultra-Plus HPLC system equipped with an XTerra MS C18 column (3.0×150 mm). Methanol and acetic acid were used in this determination were HPLC grade. Aliquots were eluted at a flow rate of 400µl/min using an isocratic mobile phase consisting of 20% water/methanol (97:2) 0.005 mM in sodium acetate, and 80% methanol/water/acetic acid (95:4:1). Analytes were detected with a mass spectrometer model LCQ using an electrospray interface. Instrument parameters were as follows: capillary temperature of 240°C, source voltage of 4.5 kV, sheath gas of 70 units without auxiliary gas, ion trap injection time of 1000 ms, and a microscan value of 1. Analytes were detected in the pseudo MS/MS mode, isolating sodium ions of TGME [M+ Na]+ at. mass 251.3 and DBM adducts [M +Na] + at. mass 229.3 and detecting the same masses without the addition of collision energy. Reference substance Benzene shows the sharpest increase with a slope greater than 0.16 d/1, reaching approx. 55% mineralization by day 6 but then decreases to approx. 40% mineralization by day 8. The mineralized fraction of test chemical increases at a rate of 0.06 d/1 until day 8 and levels off at 65% mineralization. Test chemical was not detectable in the aqueous phase of the active microcosms starting on day 3 (<0.03 ng/µl). The concentration of test chemical measured in the abiotic microcosms was well below that expected from the amount introduced. Read across substance 1,4-dibutyl (2Z)-but-2-enedioate undergoes 100% primary degradation by test mat. analysis within 3 days and 65% degradation by CO2 evolution parameter in 28 days, respectively. Thus, based on percentage degradation, 1,4-dibutyl (2Z)-but-2-enedioateis considered to be readily biodegradable in nature.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of the same read across substance 1,4-dibutyl (2Z)-but-2-enedioate (CAS no. 105-76-0) (OECD SIDS, 1996). The study was performed according to OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test) under aerobic conditions. Test inoculum was obtained from soil. Initial test substance conc. used was in the range of 31.35 – 31.5 mg/l based on DOC. Sodium benzoate was used as a reference substance for the study. An inoculum obtained from soil was incubated with 1,4 -dibutyl (2Z)-but-2 -enedioate. Reference substance Sodium benzoate undergoes atleast 95% degradation within 28 days. The percentage degradation of read across substance 1,4 -dibutyl (2Z)-but-2 -enedioate was determined to be 70% by DOC removal parameter in 10 days. The pass level for ready biodegradability was reached within 10 days. Thus, based on percentage degradation, 1,4 -dibutyl (2Z)-but-2 -enedioate is considered to be readily biodegradable in nature.

 

For the sameread across substanceMethyl Octanoate (CAS no. 111-11-5) from secondary source (Robert Murray Gerhold, 1962), biodegradation study was carried out for evaluating the percentage biodegradability of read across chemical Methyl Octanoate. Activated sludge was used as test inoculums obtained from 3 treatment plants of different sizes and designs and fed by different sewage systems. Initial test substance conc. used for the study was 500 mg/l and conc. of the inoculum used was 2,500 mg/l, respectively. Test chemical (substrates) which was poorly soluble in water were made up in 0.1 per cent concentration with distilled water and stored at 6°C until needed, but prior to addition to Warburg flasks the substrate suspensions were shaken so as to achieve an even distribution. Warburg constant temperature respirometer was used as a test vessel. They were modified 125 ml Erlenmeyer flasks fitted with 1.5 ml center-wells and female ground glass joints. Warburg flasks were cleaned by the following procedure: (a) flasks were rinsed once with tap water, and dried In the 103°C oven; (b) flasks were washed with two rinses of chloroform to remove fats and greases, then dried; (c) the flasks were submerged in potassium dichromate cleaning solution for 24 hr, rinsed In the same manner as the pipettes, and dried in an inverted position. Each flask received 10 ml of substrate solution or suspension delivered with a volumetric pipette. Next, 10 ml of blended sludge were added to each flask. The final concentration of substrate was 500 mg/liter. The final concentration of sludge solids was 2500 mg/liter. The control for endogenous respiration contained 10 ml of distilled water and 10 ml of adjusted sludge. Endogenous respiration was defined as the amount of accumulative O2uptake observed in the control flask containing sludge and distilled water. After 10-20 min of shaking for temperature equilibration the flasks were closed off to the atmosphere and shaken for 24 hr at 78 oscillations per min. From 9 to 16 readings were made during each experiment. The terms "percentage oxidized," or "percentage of oxidation," or "X per cent oxidized" mean the ratio of the amount of oxygen taken up by the sludge in the presence of that concentration of the substrate to the amount of oxygen required for complete oxidation of that concentration of substrate, i.e., oxidation to carbon dioxide, water, nitrate, and sulfate. This ratio is also referred to as the "percentage of total theoretical oxygen demand (ThOD). The percentage degradation of read across substance Methyl Octanoate was determined to be 35.4, 50.2 and 27.1%in 24 hr period by using the activated sludge obtained from three different treatment plants and theoretical O2 uptake of the test chemical was determined to be1264 mg/l, respectively. Thus, based on percentage degradation, chemical Methyl Octanoate was considered to be readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017 and EnviChem, 2014) for the read across chemical Hedione (CAS no. 24851-98-7), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance Hedione. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)). 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 Hedione was determined to be 98, 91 and 100% by BOD, TOC removal and GC parameter in 28 days. Thus, based on percentage degradation, Hedione is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemicalmethyl (2E)-non-2-enoate(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from peer reviewed journal, authoritative database J-CHECK, EnviChem and secondary source), it can be concluded that the test substancemethyl (2E)-non-2-enoatecan be expected to be readily biodegradable in nature.