β-bromostyrene

Endpoint summary

Description of key information

Biodegradation in water:

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as inoculum at concentration as 10E7 to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. .The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 69.27 %. Degradation of Sodium Benzoate exceeds  64.46 % on 7 days & 75.3 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 1.02 mgO2/mg. ThOD was calculated as 1.7 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 60 %. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Biodegradation 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 chemical. If released in to the environment, 18.7% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemicalin water is estimated to be 15 days (360hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of test chemicalin sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.552%), indicates that test chemicalis not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemical 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, 78.6 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Additional information

Biodegradation in water:

Experimental studies have reviewed from differents sources for biodegradation in water endpoint and their results are summarized below.

The first study was reviewed fro study report in this study the 42-days Closed Bottle test was performed following the OECD guideline 301 D to determine the ready biodegradability of the test item. The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used as inoculum at concentration as 10E7 to 10E8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. .The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/L. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 69.27 %. Degradation of Sodium Benzoate exceeds  64.46 % on 7 days & 75.3 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 1.02 mgO2/mg. ThOD was calculated as 1.7 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 60 %. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Next experimental study was reviewed from authoritative database (J check) in this study the Biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance. 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 was determined to be 0 and 4% degradation by BOD and GC parameter in 28 days. Thus, based on percentage degradation is considered to be not readily biodegradable in nature.

Last study was reviewed from peer reviewed journal in this Biodegradation experiment was conducted according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) for evaluating the percentage biodegradability of test substance . Initial test substance conc. used in the study was 20 mg/l. Namely, a water, acetone or DMSO solution (0.1 ml) of the test chemicals was added to a mixture of river/sea water (4.9 ml) from an unpolluted area and an autoclaved solution (5.0ml) of 0.2% peptone in a sterile test tube with a tight plug. After sealed with film and fixed at an angle of 30°in a dark box, the test tubes were incubated at 30°C and shaked at 120 rpm. Inoculum used for the study was mixed culture obtained from different sources (Sea water from Enoshima Beach and River water from Tama River). The percentage degradation of test substance in both river and sea water was determined to be 5 and 6% by BOD parameter in 3 days. Thus, based on percentage degradation, is considered to be not readily biodegradable in nature.

By considering results of all the studies mentioned above it was observed that last two studies are showing that test chemical is not readily biodegradable.Since in second study guideline is not mentioned and in third study the duration of sudy was very less therefore reults of first study has been considered and according to it test chemical is readily biodegradable.

Biodegradation 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 chemical. If released in to the environment, 18.7% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemicalin water is estimated to be 15 days (360hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of test chemicalin sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.552%), indicates that test chemicalis not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemical 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, 78.6 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.