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Biodegradation in water: screening tests

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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:
Prediction was done using OECD QSAR tool box v.3.3
GLP compliance:
not specified
Specific details on test material used for the study:
Name ( IUPAC): methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate
Molecular weight: 316.4818 g/mol
Molecular formula: C21H32O2
SMILES:CC(C)C1CCC2C(C=1)=CCC1C2(C)CCCC1(C)C(=O)OC
InChi:1S/C21H32O2/c1-14(2)15-7-9-17-16(13-15)8-10-18-20(17,3)11-6-12-21(18,4)19(22)23-5/h8,13-14,17-18H,6-7,9-12H2,1-5H3/t17-,18+,20+,21+/m0/s1
Oxygen conditions:
aerobic
Inoculum or test system:
other: Microorganisms
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation:
other: BOD
Key result
Parameter:
other: BOD
Value:
28.4
Sampling time:
28 d
Remarks on result:
other: other details not available
Details on results:
The percent biodegradability estimated of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is 28.39 % by considering BOD as parameter in 28 days.

The prediction was based on dataset comprised from the following descriptors: BOD
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

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

Domain logical expression index: "a"

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

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Alkane, branched with tertiary carbon OR Allyl OR Carboxylic acid ester OR Cyclo conjugated system OR Cycloalkane OR Cycloalkene OR Fused unsaturated carbocycles OR Isopropyl OR Rosins by Organic Functional groups ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Alkane, branched with tertiary carbon OR Allyl OR Carboxylic acid ester OR Isopropyl OR Overlapping groups OR Rosins by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Aliphatic Carbon [CH] OR Aliphatic Carbon [-CH2-] OR Aliphatic Carbon [-CH3] OR Carbonyl, aliphatic attach [-C(=O)-] OR Ester, aliphatic attach [-C(=O)O] OR Miscellaneous sulfide (=S) or oxide (=O) OR Olefinic carbon [=CH- or =C<] OR Tertiary Carbon by Organic functional groups (US EPA) ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Carbonic acid derivative OR Carboxylic acid derivative OR Carboxylic acid ester by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "f"

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

Domain logical expression index: "g"

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

Domain logical expression index: "h"

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

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as AN2 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 >> Schiff base formation OR AN2 >> Schiff base formation >> Polarized Haloalkene Derivatives OR AN2 >> Shiff base formation after aldehyde release OR AN2 >> Shiff base formation after aldehyde release >> Specific Acetate Esters 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 >> Coumarins OR Non-covalent interaction >> DNA intercalation >> DNA Intercalators with Carboxamide Side Chain 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 (indirect) or direct radical attack on DNA OR Radical >> Radical mechanism by ROS formation (indirect) or direct radical attack on DNA >> Organic Peroxy Compounds OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Coumarins OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitro Azoarenes OR SN1 OR SN1 >> Nucleophilic attack after carbenium ion formation OR SN1 >> Nucleophilic attack after carbenium ion formation >> Specific Acetate Esters OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitro Azoarenes OR SN2 OR SN2 >> Acylation OR SN2 >> Acylation >> Specific Acetate Esters 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 >> 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 >> 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 >> 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 by DNA binding by OASIS v.1.3

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OECD

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> P450 Mediated Activation to Isocyanates or Isothiocyanates OR Acylation >> P450 Mediated Activation to Isocyanates or Isothiocyanates >> Formamides OR Michael addition 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 >> Polarised Alkenes-Michael addition OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated amides OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated esters 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 >> Tertiary aromatic amine by DNA binding by OECD

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Non binder, without OH or NH2 group by Estrogen Receptor Binding

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Non binder, impaired OH or NH2 group OR Non binder, MW>500 OR Non binder, non cyclic structure OR Strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OASIS v1.3

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Direct acylation involving a leaving group OR Acylation >> Direct acylation involving a leaving group >> Azlactones and unsaturated lactone derivatives  OR Acylation >> Direct acylation involving a leaving group >> Carbamates  OR Acylation >> Ester aminolysis OR Acylation >> Ester aminolysis >> Amides OR Acylation >> Ester aminolysis or thiolysis OR Acylation >> Ester aminolysis or thiolysis >> Activated aryl esters  OR Nucleophilic addition OR Nucleophilic addition >> Addition to carbon-hetero double bonds OR Nucleophilic addition >> Addition to carbon-hetero double bonds >> Ketones OR Schiff base formation OR Schiff base formation >> Direct acting Schiff base formers OR Schiff base formation >> Direct acting Schiff base formers >> 1,2-Dicarbonyls and 1,3-Dicarbonyls  OR SN2 OR SN2 >> Nucleophilic substitution at sp3 carbon atom OR SN2 >> Nucleophilic substitution at sp3 carbon atom >> Alkyl halides  OR SN2 >> Nucleophilic substitution at sp3 carbon atom >> alpha-Activated haloalkanes  OR SN2 >> SN2 Reaction at a sp3 carbon atom OR SN2 >> SN2 Reaction at a sp3 carbon atom >> Activated alkyl esters and thioesters  OR SNAr OR SNAr >> Nucleophilic aromatic substitution on activated aryl and heteroaryl compounds OR SNAr >> Nucleophilic aromatic substitution on activated aryl and heteroaryl compounds >> Activated aryl and heteroaryl compounds by Protein binding by OASIS v1.3

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as No alert found by Protein binding by OECD

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as Acylation OR Acylation >> Direct Acylation Involving a Leaving group OR Acylation >> Direct Acylation Involving a Leaving group >> Acetates by Protein binding by OECD

Domain logical expression index: "r"

Referential boundary: The target chemical should be classified as Moderate by Bioaccumulation - metabolism half-lives ONLY

Domain logical expression index: "s"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 236 Da

Domain logical expression index: "t"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 447 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
The percent biodegradability estimated of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is 28.39 % by considering BOD as parameter and microorganism as inoculum in 28 days.
Executive summary:

Biodegradability of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate( CAS no. 127 -25 -3) is predicted using OECD QSAR tool box v.3.3 using log Kow as primary descriptor. The percent biodegradability estimated of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is 28.39 % by considering BOD as parameter and microorganism as inoculum in 28 days. Therfore it is concluded that this test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is not readily biodegradable.

Description of key information

Biodegradability of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate( CAS no. 127 -25 -3) is predicted using OECD QSAR tool box v.3.3 using log Kow as primary descriptor. The percent biodegradability estimated of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is 28.39 % by considering BOD as parameter and microorganism as inoculum in 28 days. Therfore it is concluded that this test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Predicted data for target compound methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate( CAS no. 127 -25 -3) and supporting weight of evidence studies for its closest read across chemicals with log Kow as a primary descriptor and one more supporting weight of evidence study for it read across chemical were reviewed for the biodegradation endpoint which are summarized as below.

 

Biodegradability of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate( CAS no. 127 -25 -3) is predicted using OECD QSAR tool box v.3.3 using log Kow as primary descriptor. The percent biodegradability estimated of test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is 28.39 % by considering BOD as parameter and microorganism as inoculum in 28 days. Therfore it is concluded that this test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is not readily biodegradable.

 

Another prediction done by using Estimation Programs Interface Suite (EPI suite, 2017) estimated biodegradation potential of the test compound methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate (CAS No: 127 -25 -3) in the presence of mixed populations of environmental microorganisms 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 test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate is expected to be not readily biodegradable.

 

 In the supporting weight of evidence study for read across chemical ethyl 2, 2-bis(4-chlorophenyl)-2-hydroxyacetate (CAS no.510-15-6) ( from authoritative database J check, 2017) biodegradation test was carried out by taking activated sludge as a inoculums at 30 mg/L concentration . Biodegradation was analysed by using two parameters BOD and HPLC. The initial concentration of read across chemical was 100 mg/L and study design is of standard type. After 4 weeks ( 28 days) read across chemical ethyl 2,2-bis(4-chlorophenyl)-2-hydroxyacetate showed 0% and 3% biodegradation by BOD and HPLC parameters respectively. So it is concluded that this read across chemical is not readily biodegradable.

 

 In another Supporting weight of evidence study for read across chemical Trixylyl phosphate (CAS no. 25155-23-1) ( from authoritative database J check, 2017) was carried out to analyze biodegradation by taking sludge as inoculums at 30 mg/L concentration and by using BOD and HPLC parameter. The initial concentration of read across chemical was 100 mg/L and study design is of standard type. After 4 weeks (28 days) read across chemical Trixylyl phosphate showed 0% biodegradation by BOD and HPLC parameter so it is concluded that chemical Trixylyl phosphate is not readily biodegradable.

 

One more supporting weight of evidence study was carried out by EPA High Production Volume Chemical Challenge Program, Feb 2005 for read across chemical Glycerol Ester. Biodegradation Testing was conducted according to OECD (1992) 301B Modified Sturm Test.  Inoculums used were Activated sludge microorganisms were obtained from the Haddington Municipal Sewage Treatment Works. The solids content of the sludge was 3.2 g/l.

Concentration of read across chemical: The read across was used at a concentration of 20 mg DOC/L. Based on the percentage carbon content, a target weight of 51.31 mg of read across material was weighed for direct addition to each appropriate bioreactor.

 Test Setup: Each read across item bioreactor contained 1980 ml of mineral media, 20 ml of microbial inoculum and 54 mg of read across item. The reference bioreactor contained 1911 ml of mineral media, 20 ml of microbial inoculum and 69 ml of reference material (sodium benzoate) stock. The control bioreactors each contained 1980 ml of mineral media and 20 ml of microbial inoculum. The toxicity control bioreactor contained 1911 ml of mineral media, 20 ml of microbial inoculum, and 53.9 mg of read across item and 69 ml reference material stock.

 Each bioreactor was connected to three traps, each trap containing 100 ml of 0.0125 M Ba(OH)2. At trap collection, the trap closes to the bioreactor was taken for titration, the two remaining traps were moved closer to the bioreactor and a fresh trap was placed third in line from the bioreactor. Trap changes were conducted on days 1, 4, 6, 8, 11, 15, 18, 21, 25, and 29. Each sampled trap was titrated with a few drops of phenolphthalein indicator against 0.05M HCl. The pH was determined in each bioreactor on days 0, 28 and 29; if necessary, the pH on day 0 was adjusted to 7.2-7.8.

Calculation of Results: The weight of CO2 evolved was calculated from the titre. The actual titre for each batch of The actual titre for each batch of Ba(OH)2 was used as the background titre. The mean titre for the test, reference and control vessels was calculated according to the following equation:

Weight CO2 produced (mg) = 1.1 x (background titre – ml HCl titrated)

The net CO2 production was then calculated by subtracting the control mean CO2 production from the read across and reference material mean CO2 production values. The percentage biodegradation was calculated by comparing actual CO2 evolved in read cross chemical and reference vessels with the theoretical CO2 evolution.

The read across chemical Glycerol Ester was degraded 0 % after 28 days. Under the conditions of the OECD guidelines, it cannot be considered to be readily biodegradable.

 

On the basis of results of above mentioned studies for target chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate (from OECD QSAR tool boxv3.3 and EPI suite) and supporting weight of evidence study ( from J check 2017 and EPA High Production Volume Chemical Challenge Program, Feb 2005). It is concluded that the test chemical methyl (1R,4aR,4bR,10aR)-1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylate can be expected to be not readily biodegradable.

 

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