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Biodegradation in water

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.

Additional information

Biodegradation in water

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.