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Biodegradation in water:

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.

Biodegrdation in water and sediments:

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for 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) .If released in to the environment, 5 % of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 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 in water is estimated to be 60 days (1440 hrs). The half-life (60 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is high whereas the half-life period 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 in sediment is estimated to be 541.66 days (13000 hrs) indicates that test chemical is persistent in sediment.

Biodegradation in soil:

The half-life period of 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 soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 70.01 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 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 in soil is estimated to be 120 days (2880 hrs). Based on this half-life value, it is concluded that the 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 persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Additional information

Biodegradation in water:

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.

 

Biodegrdation in water and sediments:

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for 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) .If released in to the environment, 5 % of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 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 in water is estimated to be 60 days (1440 hrs). The half-life (60 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is high whereas the half-life period 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 in sediment is estimated to be 541.66 days (13000 hrs) indicates that test chemical is persistent in sediment.

Biodegradation in soil:

The half-life period of 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 soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 70.01 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 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 in soil is estimated to be 120 days (2880 hrs). Based on this half-life value, it is concluded that the 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 persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

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