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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
Reference:
Composition 1
Qualifier:
equivalent or similar to
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
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: 1,1-diethoxy-3,7-dimethylocta-2,6-diene
- Molecular formula : C14H26O2
- Molecular weight : 226.357
- Smiles notation : C(\C=C(\CC\C=C(/C)C)C)(OCC)OCC
- InChl : 1S/C14H26O2/c1-6-15-14(16-7-2)11-13(5)10-8-9-12(3)4/h9,11,14H,6-8,10H2,1-5H3/b13-11+
- 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:
1.571
Sampling time:
28 d
Remarks on result:
other: Other details not known
Details on results:
Test substance undergoes 1.57% 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 7 nearest neighbours
Domain  logical expression:Result: In Domain

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

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Neutral Organics by US-EPA New Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Acetal OR Alkene OR Alkoxy OR Allyl OR Ether by Organic Functional groups ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Acetal OR Alkoxy OR Allyl OR Overlapping groups 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 Alpha-diether [C-O-C-O-C] OR Olefinic carbon [=CH- or =C<] OR Oxygen, aliphatic attach [-O-] by Organic functional groups (US EPA) ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Dialkylether AND Ether by Organic functional groups, Norbert Haider (checkmol)

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Not calculated by Biodeg BioHC half-life (Biowin) ONLY

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as days - weeks by Biodeg primary (Biowin 4) ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 1) ONLY

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 2) ONLY

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 5) ONLY

Domain logical expression index: "k"

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

Domain logical expression index: "l"

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

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Not categorized by Repeated dose (HESS)

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as 3-Methylcholantrene (Hepatotoxicity) Alert OR Chlorphentermine (Hepatotoxicity) Alert OR Halobenzenes (Hepatotoxicity) Rank A OR Halobenzenes (Renal toxicity) Rank A OR Nitrobenzenes (Hemolytic anemia with methemoglobinemia) Rank A OR Nitrobenzenes (Hepatotoxicity) Rank C by Repeated dose (HESS)

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 158 Da

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 287 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
not readily biodegradable
Conclusions:
The test chemical 1,1-diethoxy-3,7-dimethylocta-2,6-diene was estimated to be not readily biodegradable in water.
Executive summary:

Biodegradability of 1,1-diethoxy-3,7-dimethylocta-2,6-diene (CAS no. 7492 -66 -2) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 1.57% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical

1,1-diethoxy-3,7-dimethylocta-2,6-diene was estimated to be not readily biodegradable in water.

Description of key information

Biodegradability of 1,1-diethoxy-3,7-dimethylocta-2,6-diene (CAS no. 7492 -66 -2) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 1.57% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical

1,1-diethoxy-3,7-dimethylocta-2,6-diene was estimated to be not readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Various predicted data for the target compound1,1-diethoxy-3,7-dimethylocta-2,6-diene(CAS No. 7492-66-2) and various supporting weight of evidence studies for its closest read across substance with logKow as the primary descriptor 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 chemical 1,1-diethoxy-3,7-dimethylocta-2,6-diene(CAS No. 7492-66-2) was estimated.Test substance undergoes 1.57% degradation by BOD in 28 days (2017). Thus, based on percentage degradation, the test chemical 1,1-diethoxy-3,7-dimethylocta-2,6-diene was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound1,1-diethoxy-3,7-dimethylocta-2,6-diene(CAS No. 7492-66-2) 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 1,1 -diethoxy-3,7 -dimethylocta-2,6 -diene is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical 2,3 -dichloro-1,4 -naphthoquinone (CAS no. 117 -80 -6), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability under aerobic conditions. Initial test substance conc. used for the study was 100 mg/l. The percentage degradation of read across substance was determined to be in the range of 0 -5% by using BOD parameter in 14 days. Thus, based on percentage degradation, 2,3 -dichloro-1,4 -naphthoquinone is considered to be not readily biodegradable in nature.

 

For the same read across chemical 2,3 -dichloro-1,4 -naphthoquinone (CAS no. 117 -80 -6), biodegradation study was conducted for 14 days for evaluating the percentage biodegradability (J-CHECK, 2017). 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 5% by GC parameter in 14 days. Thus, based on percentage degradation, 2,3 -dichloro-1,4 -naphthoquinone is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2,2'-biindole-3,3'(1H,1'H)-dione (CAS no. 482 -89 -3) (OECD SIDS, 1994). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) under aerobic conditions. Concentration of inoculum i.e, sludge used was 30 mg/l as suspended solid. The percentage degradation of read across substance was determined to be 0% by BOD parameter in 28 days. Thus, based on percentage degradation, 12,2'-biindole-3,3'(1H,1'H)-dione is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study for the read across chemical 1,1'-sulfonylbis(4 -chlorobenzene) (CAS no. 80 -07 -9), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability (J-CHECK, 2017). 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 1 and 0% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation, 1,1'-sulfonylbis(4 -chlorobenzene) is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical1,1-diethoxy-3,7-dimethylocta-2,6-diene(from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, HSDB and secondary source OECD SIDS), it can be concluded that the test substance 1,1-diethoxy-3,7-dimethylocta-2,6-diene can be expected to be not readily biodegradable in nature.