1-bromo-4-fluorobenzene

Endpoint summary

Additional information

Biodegradation in water

Various study for the test compound1-Bromo-4-fluorobenzene(CAS No. 460-00-4) and for its read across substance were reviewed for the biodegradation end point which are summarized as below:

Biodegradation study was conducted for 72 hrs for evaluating the percentage biodegradability of test substance 1-Bromo-4-fluorobenzene by using a microbial mixture as an inoculum (CLAIRGEO ULDINGC.,J et. al; 1988). Initial test substance conc. used in the study was 200 mg/l. Microbial mixture was used as an inoculum. The mixture consisted of fivePseudomonads, oneKlebsiella, fourRhodococciand two fungal strains. The strains are held in the culture bank at Inter- Bio Laboratories and are encoded as follows: Ps4.3; Ps4.24; Ps7.16; P~7.24; Ps7.47; K12; Rh17.2; Rh7.2; Rh4.1; Rh8.1; Fgi3.25 and Fgi3.21, respectively.

The organisms were stabilized on a cereal base by air-drying or freeze-drying and subsequently blended. They were rehydrated in water (10 g in 90 ml) shaken for1h at 30°C and allowed to settle for5min at room temperature. The supernatant fluid (10 ml) was centrifuged at 7000 rev/min for 10 min; the pellet was then washed and used to inoculate 100 ml of medium.

The basal salts medium used in the degradation tests contained (g/l): KH2PO4,4.36;Na2HPO4. 2H2O,3.45;NH4Cl,1.0;MgSO4,.7H2O,0.48; CaCI2, .2H2O,0.036;FeSO4, 0.002; MnCl2,OGO1;CoCI2, 0.001.The medium was distributed in 100 ml lots in 500 ml baffled Erlenmyer flasks. 1,4 -Bromo fluorobenzene (used as Carbon source) was prepared as a 1000-fold stock solution in ethanol, filter sterilized(0.45pmMillipore) and added to the basal medium after sterilization. After inoculation, flasks were incubated on an orbital shaker at150rev/min at 30°C.Uninoculated control flasks were incubated in parallel. Samples were removed at 24 h intervals and analysed for substrate concentration by high performance liquid chromatography (Shimadzu LC4A system).

For HPLC analysis, volumes of 5 ml were extracted using 2 ml volumes of ethyl acetate in three successive extractions. The resulting organic phase was filtered through a 0.2pmPTFE filter (Gelman) and the filtrate used directly for analysis. Samples were separated on a Nucleosil5C18150 x 4.6mm column using either acetonitrile/water or acetonitrile/acetic acid as the mobile phase and were detected using a U.V. detector. In the degradation test conducted, no lag period was observed. The percentage degradation of test substance was determined to be 100% by HPLC in 72 hrs. Thus, the test chemical1-Bromo-4-fluorobenzene was considered to be readily biodegradable in nature.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance1,4-Dichlorobenzene by using a settled domestic wastewater as microbial inoculum (Henry H. Tabak et. al; 1988). Settled domestic wastewater was used as a microbial inoculum. Conc. of test substance used for the study are 5 and 10 mg/l, respectively.Biochemical oxygen demand (BOD) dilution water containing 5mg of yeast extract per litre, was used as the synthetic medium.

Stock solution of test substance was prepared in absolute ethanol. Stock solutions were prepared as 10% solutions. Study was performed in stoppered reagent bottles to minimize the volatization of the substrate. Test also involve the incorporation of both the medium-inoculum control to serve as blank control for determining base lines for both GC analysis and for DOC and TOC as well as the medium-substrate control series for determination of possible autooxidation, photolysis, and volatilization.

Homogenous suspension of 1,4-dichlorobenzes in the synthetic medium were prepared by adding appropriate amounts of tributerin® stock solutions of these test compounds to prechilled synthetic medium in a heavy-duty blender and blending the medium for 2 mins. The substrate containing synthetic media were stored in 2 L glass stoppered reagent bottles in a refrigerator before use. Both the unblended and blended substrate containing media in reagent bottles were inoculated with prechilled yeast extract (5 mg/l) and settled domestic wastewater inoculum. These experimental bottles were incubated first for 7 days in a static incubation in a constant temperature room at 25°C in darkness, followed by three weekly subcultures (totaling 28 days of incubation).

Duplicate samples at the beginning of each incubation period and triplicate samples at the end of the 7-day incubation for the original and each subculture were subjected to GC, TOC and DOC analysis. Extraction efficiency of test chemical and percentage recovery ranged from 83% and 98% and was fairly reproducible for several test runs of test compound. The percentage degradation of test substance was determined to be 61% byGC, TOC or DOC analysis in a 28 day study. Based on the percentage degradation, the test chemical1,4-Dichlorobenzenewas considered to be readily biodegradable in water.

 

Biodegradation study was conducted for 96 hrs for evaluating the percentage biodegradability of read across substance 1,4-Dichlorobenzeneby using a microbial mixture as an inoculum (CLAIRGEO ULDINGC.,J et. al; 1988). Initial test substance conc. used in the study was 200 mg/l.Microbial mixture was used as an inoculum. The mixture consisted of five pseudomonads, one klebsiella, four rhodococci and two fungal strains. The strains are held in the culture bank at Inter- Bio Laboratories and are encoded as follows: Ps4.3; Ps4.24; Ps7.16; P~7.24; Ps7.47; K12; Rh17.2; Rh7.2; Rh4.1; Rh8.1; Fgi3.25 and Fgi3.21, respectively.

The organisms were stabilized on a cereal base by air-drying or freeze-drying and subsequently blended. They were rehydrated in water (10 g in 90 ml) shaken for1h at 30°C and allowed to settle for 5min at room temperature. The supernatant fluid (10 ml) was centrifuged at 7000 rev/min for 10 min; the pellet was then washed and used to inoculate 100 ml of medium.

The basal salts medium used in the degradation tests contained (g/l): KH2PO4,4.36;Na2HPO4. 2H2O,3.45;NH4Cl,1.0;MgSO4,.7H2O,0.48; CaCI2, .2H2O,0.036;FeSO4, 0.002; MnCl2,OGO1;CoCI2, 0.001.The medium was distributed in 100 ml lots in 500 ml baffled Erlenmyer flasks.1,4-Dichlorobenzene(used as Carbon source) was prepared as a 1000-fold stock solution in ethanol, filter sterilized(0.45pmMillipore) and added to the basal medium after sterilization. After inoculation, flasks were incubated on an orbital shaker at150rev/min at 30°C.Uninoculated control flasks were incubated in parallel. Samples were removed at 24 h intervals and analysed for substrate concentration by high performance liquid chromatography (Shimadzu LC4A system).

For HPLC analysis, volumes of 5 ml were extracted using 2 ml volumes of ethyl acetate in three successive extractions. The resulting organic phase was filtered through a 0.2pmPTFE filter (Gelman) and the filtrate used directly for analysis. Samples were separated on a Nucleosil5C18150 x 4.6mm column using either acetonitrile/water or acetonitrile/acetic acid as the mobile phase and were detected using a U.V. detector. In the degradation test conducted, no lag period was observed. The percentage degradation of test substance was determined to be 100% by HPLC in 96 hrs. Thus, the test chemical 1,4-Dichlorobenzene was considered to be readily biodegradable in nature.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 4-Bromobiphenyl (J-CHECK, 2016). Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l. The percentage degradation of test substance was determined to be 73% by BOD and 77% by HPLC in 28 days. Thus, the substance 4-Bromobiphenyl is considered to be readily biodegradable in nature.

Biodegradation study was conducted for 72 hrs for evaluating the percentage biodegradability of read across substance 4-Chlorotoluene by using a microbial mixture as an inoculum (CLAIRGEO ULDINGC.,J et. al; 1988). Initial test substance conc. used in the study was 200 mg/l. Microbial mixture was used as an inoculum. The mixture consisted of fivePseudomonads, oneKlebsiella, fourRhodococciand two fungal strains. The strains are held in the culture bank at Inter- Bio Laboratories and are encoded as follows: Ps4.3; Ps4.24; Ps7.16; P~7.24; Ps7.47; K12; Rh17.2; Rh7.2; Rh4.1; Rh8.1; Fgi3.25 and Fgi3.21, respectively.

The organisms were stabilized on a cereal base by air-drying or freeze-drying and subsequently blended. They were rehydrated in water (10 g in 90 ml) shaken for1h at 30°C and allowed to settle for5min at room temperature. The supernatant fluid (10 ml) was centrifuged at 7000 rev/min for 10 min; the pellet was then washed and used to inoculate 100 ml of medium.

The basal salts medium used in the degradation tests contained (g/l): KH2PO4,4.36;Na2HPO4. 2H2O,3.45;NH4Cl,1.0;MgSO4,.7H2O,0.48; CaCI2, .2H2O,0.036;FeSO4, 0.002; MnCl2,OGO1;CoCI2, 0.001.The medium was distributed in 100 ml lots in 500 ml baffled Erlenmyer flasks.4-Chlorotoluene(used as Carbon source) was prepared as a 1000-fold stock solution in ethanol, filter sterilized(0.45pmMillipore) and added to the basal medium after sterilization. After inoculation, flasks were incubated on an orbital shaker at150rev/min at 30°C.Uninoculated control flasks were incubated in parallel. Samples were removed at 24 h intervals and analysed for substrate concentration by high performance liquid chromatography (Shimadzu LC4A system).

For HPLC analysis, volumes of 5 ml were extracted using 2 ml volumes of ethyl acetate in three successive extractions. The resulting organic phase was filtered through a 0.2pmPTFE filter (Gelman) and the filtrate used directly for analysis. Samples were separated on a Nucleosil5C18150 x 4.6mm column using either acetonitrile/water or acetonitrile/acetic acid as the mobile phase and were detected using a U.V. detector. In the degradation test conducted, no lag period was observed. The percentage degradation of test substance was determined to be 100% by HPLC in 72 hrs. Based on the percentage degradation, the test chemical 4 -Chlorotoluene was considered to be readily biodegradable in water.

Biodegradation study was conducted according to OECD TG 301 C guideline for evaluating the percentage biodegradability of read across substance4-Chlorotoluene (Kondo, M et. al; 1988).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 120rpm. Inoculum used for the study was mixed culture obtained from different sources (Sea water from Tama river and River water from Enoshima Beach). The percentage degradation of test substance was found to be 44% and 64% in 3 days, respectively. Thus, the substance 4 -Chlorotoluene was determined to be readily biodegradable in nature.

On the basis of above results for target and read across substance, it can be concluded that the test substance1-Bromo-4-fluorobenzenecan be expected to be readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI) Suite (2016) prediction model was run to predict the half-life in water and sediment for the test compound 1-Bromo-4-fluorobenzene (CAS No. 460 -00 -4). If released in to the environment, 31.4 % of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 1-Bromo-4-fluorobenzene in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 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 1-Bromo-4-fluorobenzene in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.657%), indicates that 1-Bromo-4-fluorobenzene is not persistent in nature.

Biodegradation in soil

The half-life period of 1-Bromo-4-fluorobenzene (CAS No. 460 -00 -4) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2016). If released into the environment, 41.2% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 1-Bromo-4-fluorobenzene in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 1-Bromo-4-fluorobenzene, 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.

On the basis of available information, the test substance1-Bromo-4-fluorobenzenecan be considered to be readily biodegradable in nature.