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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:
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: 6-Methoxy-2-naphthaldehyde
- Molecular formula: C12H10O2
- Molecular weight: 186.209 g/mol
- Smiles notation: COc1ccc2cc(ccc2c1)C=O
- InChl: 1S/C12H10O2/c1-14-12-5-4-10-6-9(8-13)2-3-11(10)7-12/h2-8H,1H3
- Substance type: Organic
- Physical state: Solid
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:
92.6
Sampling time:
28 d
Remarks on result:
other: Other details not known
Details on results:
Test substance undergoes 92.6% 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 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 "i" )  and "j" )  and "k" )  and ("l" and ( not "m") )  )  and "n" )  and ("o" and "p" )  )

Domain logical expression index: "a"

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

Domain logical expression index: "b"

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

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Aldehydes (Mono) by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Aldehyde OR Aryl OR Ether OR Fused carbocyclic aromatic OR Naphtalene by Organic Functional groups ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Aldehyde OR Ether OR Fused carbocyclic aromatic OR Naphtalene OR Overlapping groups by Organic Functional groups (nested) ONLY

Domain logical expression index: "f"

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

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Aldehyde OR Alkylarylether OR Aromatic compound OR Carbonyl compound OR Ether by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "h"

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

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 5) ONLY

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 2) ONLY

Domain logical expression index: "k"

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

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as No Data by Ultimate biodeg

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as > 100 days by Ultimate biodeg

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as High (Class III) by Toxic hazard classification by Cramer (with extensions) ONLY

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 92 Da

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 230 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
The test chemical 6-Methoxy-2-naphthaldehyde was estimated to be readily biodegradable in water.
Executive summary:

Biodegradability of 6-Methoxy-2-naphthaldehyde (CAS no. 3453 -33 -6) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 92.6% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 6-Methoxy-2-naphthaldehyde was estimated to be readily biodegradable in water.

Description of key information

Biodegradability of 6-Methoxy-2-naphthaldehyde (CAS no. 3453 -33 -6) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 92.6% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 6-Methoxy-2-naphthaldehyde 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 6-Methoxy-2-naphthaldehyde (CAS No. 3453-33-6) 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 chemical 6-Methoxy-2-naphthaldehyde(CAS No. 3453-33-6) was estimated.Test substance undergoes 92.6% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 6-Methoxy-2-naphthaldehyde 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 6-Methoxy-2-naphthaldehyde(CAS No. 3453-33-6) 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  6-Methoxy-2-naphthaldehyde is expected to be readily biodegradable.

 

In a supporting weight of evidence study from authoritative database (J-CHECK and HSDB, 2017) for the read across chemical 1-butoxypropan-2-ol (CAS no. 121-33-5), biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 1-butoxypropan-2-ol. 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 substance 1-butoxypropan-2-ol was determined to be 97, 99 and 100% by BOD, TOC removal and HPLC parameter in 14 days. Thus, based on percentage degradation,1-butoxypropan-2-ol is considered to be readily biodegradable in nature.

 

For the read across substance 2-Methoxybenzaldehyde (CAS no. 135-02-4) from peer reviewed journal (Gerhard Zellner et. al; 1990), biodegradation study was conducted under anaerobic conditions for 28 days for evaluating the percentage biodegradability of read across substance 2-methoxybenzaldehyde. Test chemical 2-methoxybenzaldehyde were of analytical grade and were purchased from Serva (Heidelberg, Federal Republic of Germany), Merck, or Aldrich Chemie GmbH & CoKG (Steinheim, Federal Republic of Germany). Desulfovibrio vulgaris Marburg DSM 2119 and Desulfovibrio sp. strain MP47 was used as an inoculum for the study. Desulfovibrio vulgaris Marburg DSM 2119 was obtained from Hans Hippe, Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Braunschweig, Federal Republic of Germany and Desulfovibrio sp. strain MP47 was isolated from a laboratory digester. Strain MP47 is presumably another strain of Desulfovibrio vulgaris. Desulfovibrio vulgaris Marburg DSM 2119 and Desulfovibrio sp. strain MP47 were routinely cultured in a medium that contained the following (per liter): 4.25 g of Na2SO4, 0.255 g of K2HPO4, 0.255 g of KH2PO4, 0.255 g of (NH4)2S04, 0.45 g of NaCl, 0.10 g of MgSO4 - 7H20, 2.0 g of yeast extract, 60 mg of CaCl2, 4 mg of FeSO4, 24 mg of Ni(NH4)2(SO4)2, and 1 mg of resazurin. The medium was supplemented with 10 ml each of vitamin and mineral solutions and reduced by the addition of 0.5 g of L-cysteine hydrochloride and 0.5 g of Na2S 9H20 per liter.The pH of the medium was adjusted to 7.0. Cultures were grown at 37°C on a rotary shaker at 100 rpm. Utilization of yeast extract components as electron donors was tested in the same medium with an N2-CO2 (80:20%; 300 kPa) gas atmosphere.Serum bottles was used as a test vessel for the study. Initial test substance conc. used in the study was 250 mg/l. Parallel cultures in serum bottles containing 20 ml of medium and 250 mg of substrate per liter were incubated under N2-CO2 (80:20%, 300 kPa) at 37°C on a shaker (100 rpm) for 4 weeks. Biotransformation of the substrates was analyzed by at least two methods, including HPLC with two detector systems, UV spectroscopy at 254 nm and thin-layer chromatography. The percentage degradation of substance 2-methoxybenzaldehyde was determined to be 80% by HPLC, UV-Vis and TLC parameter in 28 days. The chemical was transformed into the respective benzoic acids. Thus, based on percentage degradation, 2-methoxybenzaldehyde is considered to be readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) and secondary source (OECD SIDS, 2009) for the read across chemical 4-Methoxybenzaldehyde (CAS no. 123-11-5),biodegradation experiment was conducted for 14 days for evaluating the percentage biodegradability of read across substance 4-methoxybenzaldehyde.The study was performed according to OECD Guideline 301C “Ready biodegradability: Modified MITI Test (I)” under aerobic conditions. Activated sludge was used as a test inoculum. Sludge and surface water including surface soil were collected from ten different places in Japan which includes water treatment plants, rivers, lake and inner bays. These sludge and water/soil were mixed and cultivated with glucose and peptone as nutrient in a testing laboratory. 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. Aniline was used as a reference substance for the study. Portion of the test solution was taken out followed by the centrifuge separation. Then, the supernatant solution was employed for the quantitative analysis for HPLC and TOC. BOD was continuously measured by BOD analysis over 14 days. Direct analysis by HPLC and TOC analysis were conducted after 28 days. The percentage degradation of substance 4-methoxybenzaldehyde was determined to be 99, 98 and 100% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, 4-methoxybenzaldehyde is considered to be readily biodegradable in nature.

 

Another biodegradation studywas conducted for 28 days for evaluating the percentage biodegradability of read across substance 4-methoxybenzaldehyde (CAS no. 123-11-5) (HPVIS, 2017). The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions at a temperature range of 17-22°C. Activated sludge was used as a test inoculum for the study. Initial test substance conc. used in the study was 10 mg/l. Concentration of inoculum used was10% by volume of secondary effluent from an unacclimatised activated sludge. The mean percentage biodegradation was calculated from 4 vessels on day 28. The percentage degradation of substance 4 -methoxy benzaldehyde was determined to be 94.9% by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, 4 -methoxybenzaldehyde is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemical 6-Methoxy-2-naphthaldehyde (from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK, HSDB, peer reviewed journals and secondary source), it can be concluded that the test substance 6-Methoxy-2-naphthaldehyde can be expected to be readily biodegradable in nature.