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Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data is from peer reviewed journal
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Biodegradation study was conducted for evaluating the percentage biodegradability of test substance 3,3-Dimethyl-8,9-dinorbornan-2-one.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (IUPAC name): 3,3-Dimethyl-8,9-dinorbornan-2-one
- Common name: 1,3,3-trimethylbicyclo[2.2.1]heptan-2-one
- Molecular formula: C10H16O
- Molecular weight: 152.2354 g/mol
- Smiles notation: C[C@@]12CC[C@@H](C1)C(C)(C)C2=O
- InChl: 1S/C10H16O/c1-9(2)7-4-5-10(3,6-7)8(9)11/h7H,4-6H2,1-3H3/t7-,10+/m0/s1
- Substance type: Organic
- Physical state: Liquid
- Other: d-,1-Fenchone was distilled through a 24 inch Vigreux column at 190-191.5° and chromatographed on Florisil.
Oxygen conditions:
not specified
Inoculum or test system:
other: Corynebacterium spp. (Bacteria)
Details on inoculum:
- Method of cultivation: Corynebacterium sp., strain T1, was inoculated from stock culture slants into 100 ml sterile nutrient broth (Difco; 8.0 g/liter) and grown at 30°C with shaking for 24 hours. Then, 10 ml portions were used to inoculate the test vessel containing the test chemical fenchone.
Duration of test (contact time):
48 h
Initial conc.:
250 000 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
other: Thin Layer Chromatography (TLC) and Gas Chromatography (GC)
Details on study design:
TEST CONDITIONS
- Test temperature: 30°C

TEST SYSTEM
- Culturing apparatus: Erlenmeyer flasks were used as a test vessel for the study.
- Number of culture flasks/concentration: 6 repilcates
Key result
Parameter:
other: Thin Layer Chromatography (TLC) and Gas Chromatography (GC)
Sampling time:
48 h
Remarks on result:
other: %degradation value of chemical was not known, but chemical fenchone undergoes degradation by Corynebacterium spp. giving rise to 1,2- and 2,3-fencholides, respectively.
Details on results:
A mixture of authentic 1,2- and 2,3-fencholides, obtained by the Baeyer-Villiger oxidation of fenchone with peracetic acid, showed essentially the same chromatographic properties as the biologically derived material. It will be noted that the major component corresponds to the 1,2-fencholide.

Table: Chromatographic Properties of Fenchone and Related Compounds.   

 

Compound

 

Rf*

 

Retention time+ on

SE-30

Butanediol succinate polyester

 

Fenchone (3,3-Dimethyl-8,9-dinorbornan-2-one)

-

0.72

 

-

 

 

Where,

* =Thin layer chromatography on silica gel plates activated at 110°C for 30 minutes and developed with ether-light petroleum (40:60 v/v).

 

+ =Vapor phase chromatography retention times in minutes after emergence of solvent. Both SE-30 and butanediol succinate polyester were maintained at 150°.

Validity criteria fulfilled:
not specified
Interpretation of results:
other: biodegradable
Conclusions:
A mixture of authentic 1,2- and 2,3-fencholides, obtained by the Baeyer-Villiger oxidation of 3,3-Dimethyl-8,9-dinorbornan-2-one (fenchone) with peracetic acid, showed essentially the same chromatographic properties as the biologically derived material. It will be noted that the major component corresponds to the 1,2-fencholide. Thus, based on this, 3,3-Dimethyl-8,9-dinorbornan-2-one is considered to be biodegradable in water.
Executive summary:

Biodegradation study was conducted for evaluating the percentage biodegradability of test substance 3,3-Dimethyl-8,9-dinorbornan-2-one (CAS no. 1195-79-5).Corynebacterium spp. (Bacteria), an organism which grows at the expense of either (+)- or (-)- camphor was used as a test inoculum for the study. Corynebacterium sp., strain T1, was inoculated from stock culture slants into 100 ml sterile nutrient broth (Difco; 8.0 g/liter) and grown at 30°C with shaking for 24 hours. Then, 10 ml portions were used to inoculate the test vessel containing the test chemical 3,3-Dimethyl-8,9-dinorbornan-2-one. Ten ml portions were used to inoculate six 2 liter Erlenmeyer flasks each containing 400 ml of sterile broth. After 24 hours incubation 2.4 g3,3-Dimethyl-8,9-dinorbornan-2-onein N,N,-dimethyl formamide (0.25 g/ml) was equally divided among all six flasks and incubation continued for a further 24 hours. The cells were then centrifuged and the clear neutral supernatant extracted 3 times with 0.5 vol. diethyl ether. The ether solution, after drying over anhydrous Na2SO4, was taken to dryness and 1.12 g of pale yellow crystalline solid obtained. When crystallized from light petroleum (b.p. range 60-68°C) at -72°C, the material had m.p. 73-75°C, λCHCl3max 5.48µ (Found: C, 70.82; H 9.49. C10H16O2 requires C, 71.4; H, 9.52). Thin layer chromatography on silica gel G Drinkmann with ether-light petroleum (40:60, v/v) as solvent, revealed a single component reacting with alkaline hydroxylamine and detectable as its purple ferric hydroxamate. Gas chromatography on a stationary phase of 5% silicone gum rubber SE-30 at 150°C gave only a single peak but on 5% butanediol succinate polyester at 150°C a second component, approximately 10% of the total peak area, was distinguishable. A mixture of authentic 1,2- and 2,3-fencholides, obtained by the Baeyer-Villiger oxidation of 3,3-Dimethyl-8,9-dinorbornan-2-one (fenchone) with peracetic acid, showed essentially the same chromatographic properties as the biologically derived material. It will be noted that the major component corresponds to the 1,2-fencholide.Thus, based on this, 3,3-Dimethyl-8,9-dinorbornan-2-one is considered to be biodegradable in nature.

Description of key information

Biodegradation study was conducted for evaluating the percentage biodegradability of test substance 3,3-Dimethyl-8,9-dinorbornan-2-one (CAS no. 1195-79-5) (P. J. Chapman, et. al; 1965). Corynebacterium spp. (Bacteria), an organism which grows at the expense of either (+)- or (-)- camphor was used as a test inoculum for the study. Corynebacterium sp., strain T1, was inoculated from stock culture slants into 100 ml sterile nutrient broth (Difco; 8.0 g/liter) and grown at 30°C with shaking for 24 hours. Then, 10 ml portions were used to inoculate the test vessel containing the test chemical 3,3-Dimethyl-8,9-dinorbornan-2-one. Ten ml portions were used to inoculate six 2 liter Erlenmeyer flasks each containing 400 ml of sterile broth. After 24 hours incubation 2.4 g3,3-Dimethyl-8,9-dinorbornan-2-onein N,N,-dimethyl formamide (0.25 g/ml) was equally divided among all six flasks and incubation continued for a further 24 hours. The cells were then centrifuged and the clear neutral supernatant extracted 3 times with 0.5 vol. diethyl ether. The ether solution, after drying over anhydrous Na2SO4, was taken to dryness and 1.12 g of pale yellow crystalline solid obtained. When crystallized from light petroleum (b.p. range 60-68°C) at -72°C, the material had m.p. 73-75°C, λCHCl3max 5.48µ (Found: C, 70.82; H 9.49. C10H16O2 requires C, 71.4; H, 9.52). Thin layer chromatography on silica gel G Drinkmann with ether-light petroleum (40:60, v/v) as solvent, revealed a single component reacting with alkaline hydroxylamine and detectable as its purple ferric hydroxamate. Gas chromatography on a stationary phase of 5% silicone gum rubber SE-30 at 150°C gave only a single peak but on 5% butanediol succinate polyester at 150°C a second component, approximately 10% of the total peak area, was distinguishable. A mixture of authentic 1,2- and 2,3-fencholides, obtained by the Baeyer-Villiger oxidation of 3,3-Dimethyl-8,9-dinorbornan-2-one (fenchone) with peracetic acid, showed essentially the same chromatographic properties as the biologically derived material. It will be noted that the major component corresponds to the 1,2-fencholide.Thus, based on this, 3,3-Dimethyl-8,9-dinorbornan-2-one is considered to be biodegradable in nature.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Experimental key study and supporting data for the target compound 3,3-Dimethyl-8,9-dinorbornan-2-one (CAS No. 1195-79-5) and supporting study for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (P. J. Chapman, et. al; 1965),biodegradation study was conducted for evaluating the percentage biodegradability of test substance 3,3-Dimethyl-8,9-dinorbornan-2-one (CAS no. 1195-79-5).Corynebacterium spp. (Bacteria), an organism which grows at the expense of either (+)- or (-)- camphor was used as a test inoculum for the study. Corynebacterium sp., strain T1, was inoculated from stock culture slants into 100 ml sterile nutrient broth (Difco; 8.0 g/liter) and grown at 30°C with shaking for 24 hours. Then, 10 ml portions were used to inoculate the test vessel containing the test chemical 3,3-Dimethyl-8,9-dinorbornan-2-one. Ten ml portions were used to inoculate six 2 liter Erlenmeyer flasks each containing 400 ml of sterile broth. After 24 hours incubation 2.4 g3,3-Dimethyl-8,9-dinorbornan-2-onein N,N,-dimethyl formamide (0.25 g/ml) was equally divided among all six flasks and incubation continued for a further 24 hours. The cells were then centrifuged and the clear neutral supernatant extracted 3 times with 0.5 vol. diethyl ether. The ether solution, after drying over anhydrous Na2SO4, was taken to dryness and 1.12 g of pale yellow crystalline solid obtained. When crystallized from light petroleum (b.p. range 60-68°C) at -72°C, the material had m.p. 73-75°C, λCHCl3max 5.48µ (Found: C, 70.82; H 9.49. C10H16O2 requires C, 71.4; H, 9.52). Thin layer chromatography on silica gel G Drinkmann with ether-light petroleum (40:60, v/v) as solvent, revealed a single component reacting with alkaline hydroxylamine and detectable as its purple ferric hydroxamate. Gas chromatography on a stationary phase of 5% silicone gum rubber SE-30 at 150°C gave only a single peak but on 5% butanediol succinate polyester at 150°C a second component, approximately 10% of the total peak area, was distinguishable. A mixture of authentic 1,2- and 2,3-fencholides, obtained by the Baeyer-Villiger oxidation of 3,3-Dimethyl-8,9-dinorbornan-2-one (fenchone) with peracetic acid, showed essentially the same chromatographic properties as the biologically derived material. It will be noted that the major component corresponds to the 1,2-fencholide.Thus, based on this, 3,3-Dimethyl-8,9-dinorbornan-2-one is considered to be biodegradable in nature.

 

In a supporting study from peer reviewed journal (B. C. J. Zoeteman, et. al; 1981), persistence of the test chemical  3,3-Dimethyl-8,9-dinorbornan-2-one (CAS no. 1195-79-5) was determined in groundwater at Netherlands and Noordwijk, respectively .The estimated half-life value of chemical in groundwater at Netherlands and Noordwijk was determined to be 109.5 and 219 days, respectively. Thus, based on this, 3,3 -Dimethyl-8,9 -dinorbornan-2 -one is considered as persistent in water and can be evaluated to be not readily biodegradable in nature.

 

For the read across chemical (1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one (CAS no. 76-22-2) from authoritative database (J-CHECK and HSDB, 2017), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of the read across substance(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one(CAS no. 76-22-2). The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge was used as a test inoculums for the study. 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 test substance (1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one was determined to be 94% and 100% by BOD and GC parameter in 28 days. Thus, based on percentage degradation, (1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-one is considered to be readily biodegradable in nature.

 

Although the supporting estimated data for the target chemical 3,3-Dimethyl-8,9-dinorbornan-2-one indicates that the chemical is not readily biodegradable, but based onthe experimental key study (from peer reviewed journal) which indicates that the target chemical 3,3-Dimethyl-8,9-dinorbornan-2-one is biodegradable in 48 hrs resulting in the biodegradable products as 1,2- and 2,3-fencholides, respectively, it can be considered that the chemical is expected to be readily biodegradable in 28 days and for its read across substance (from authoritative database J-CHECK and HSDB), it can be concluded that the test substance 3,3-Dimethyl-8,9-dinorbornan-2-one can be expected to be readily biodegradable in nature.