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Biodegradation in water

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance C.I. Solvent Red 49 (CAS no. 509 -34 -2) (J-CHECK, 20016). 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 0 and 1% degradation by BOD, TOC removal and HPLC in 28 days.  Thus, based on percentage degradation, C.I. Solvent Red 49 was considered to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI) Suite (2017) prediction model was run to predict the half-life in water and sediment for the test compound C.I. Solvent Red 49 (CAS No. 509 -34 -2). If released in to the environment, 1.36% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 180 days (4320 hrs). The half-life (180 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high whereas the half-life period of test chemical C.I. Solvent Red 49 in sediment is estimated to be 1620.833 days (38900 hrs). Based on this half-life value (1620.833 days), it indicates that the chemical C.I. Solvent Red 49 is persistent in sediment.

Biodegradation in soil

The half-life period of C.I. Solvent Red 49 (CAS No. 509 -34 -2) 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, 48.3% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of C.I. Solvent Red 49 in soil is estimated to be 360 days (8640 hrs). Based on this half-life value of C.I. Solvent Red 49, it is concluded that the chemical is persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to high.

Additional information

Biodegradation in water

1 experimental study and 2 predicted data for the test compound C.I. Solvent Red 49 (CAS No. 509-34-2) and the 4 different studies for its closest read across substancesusing log kow as the primary descriptorwere reviewed for the biodegradation endpoint, which are summarized as below:

 

Study 1 - Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance C.I. Solvent Red 49 (CAS no. 509 -34 -2) (J-CHECK, 20016). 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 0 and 1% degradation by BOD, TOC removal and HPLC in 28 days.  Thus, based on percentage degradation, C.I. Solvent Red 49 was considered to be not readily biodegradable in nature.

 

Study 2 - Estimation Programs Interface Suite (EPI suite, 2017) was run to predict the biodegradation potential of the test compound C.I. Solvent Red 49 (CAS no. 509 -34 -2) in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance 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 C.I. Solvent Red 49 is expected to be not readily biodegradable.

 

Study 3- Biodegradability of C.I. Solvent Red 49 (CAS no. 509 -34 -2) is predicted using QSAR toolbox version 3.4 (2017). Test substance undergoes 15.77% degradation by CO2 evolution in 28 days. Thus, based on percentage degradation, the test chemical C.I. Solvent Red 49 was estimated to be not readily biodegradable in water.

 

Study 4 - For a read across chemical Uranine (CAS no. 518 -47 -8), a combination of two biodegradation tests (Closed Bottle test and Manometric Respiratory test, OECDs 301 D, F) was carried out to investigate the biodegradability of the read across substance Uranine (CAS no. 518-47-8) (Lukasz Gutowski et. al, 2015). Closed Bottle Test was performed according to the guidelines of the Organization for Economic Co-operation and Development OECD 301D. This test is characterized by low bacteria density (102–105 colony forming units (CFUs)/mL), low nutrient content, and constant temperature (20 ± 1 °C) and it was kept in the dark. The average biodegradation value after 28 days for Uranine monitored by measurement of the oxygen concentration was 7.6. Based on the results obtained, Uranine is expected to be not readily biodegradable.

 

Study 5 - For a read across chemical Uranine (CAS no. 518 -47 -8),acombination of two biodegradation tests (Closed Bottle test and Manometric Respiratory test, OECDs 301 D, F) was carried out to investigate the biodegradability of the read across substance Uranine (CAS no. 518-47-8) (Lukasz Gutowski et. al, 2015).

The Manometric Respiratory tests works with higher bacterial density (5–10×106CFUs/mL) and diversity as the Closed Bottle test thus increasing the probability for biodegradation. This test was performed according to the OECD guidelines (OECD, 1992) in the dark at room temperature (20 ± 1 °C) under gentle stirring. CO2 production as the parameter of the endpoint biodegradation was measured indirectly by the OxiTop OC110-system.

The concentration of standard solution for uranine was 16.7 mg/L, corresponding to the theoretical oxygen demand ThOD of 30 mg/L. Inoculum was derived from the municipal sewage treatment plant (Lüneburg, Germany).Aliquots (measuring) of 80ml of inoculum were added to 1 L of mineral medium. The test consisted of four different series: (i) a blank series (containing only the mineral medium and inoculum), (ii) quality control (containing readily biodegradable sodium acetate as the only relevant carbon source apart from the inoculum), (iii) a test series (containing the target compound) and (iv) toxicity control (containing target compound and sodium acetate as carbon source). The amount of sodium acetate for each series corresponded to ThOD of 5 mg/L. A compound is qualified as “ready biodegradable” when 60% of ThOD expressed as percentage of oxygen consumption is consumed within a period of 10 days after the oxygen uptake reached 10% of ThOD. Samples from the beginning (day 0) and the end of the test (day 28) were collected and stored at−20 °C until analysis with HPLC-FLD and LC–M/MS. No toxic effects on bacteria were observed in the toxicity control as well as no degradation was observed in the sterile control. The measurements with HPLC-FLD confirmed that no elimination of uranine occurred during the Manometric Respiratory Test. Only 0.1% degradation of test substance Uranine was observed. The reason for the negative values in Manometric Respiratory test might be interpreted as high degradation in the blank control and should be considered could be due to some background in the blanks and can be considered as 0% degradation of the test substance. Based on the results obtained in Manometric Respiratory test method, Uranine is expected to be not readily biodegradable.

 

Study 6 - In a weight of evidence study of read across chemical Uranine (CAS no. 518 -47 -8),biodegradation screening test was conducted according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) for 28 days (4 weeks) for evaluating the percentage biodegradability of the read across substance Uranine (CAS no. 518-47-8) (J-CHECK, 20016). The purity of test substance by HPLC was found to be 92.1% and water solubility value is ≥ 300 g/l at 20ᵒC (Flask method). Concentration of inoculum i.e, sludge is 30 mg/l and initial test substance conc. used in the study is 100 mg/l. The percentage degradation of read across substance is determined to be 0% by O2 consumption and by TOC removal whereas only 1% degradation was observed by HPLC. Thus, based on percentage degradation, substance Fluorescein sodium is considered to be not readily biodegradable in nature.

 

Study 7- In an another weight of evidence study of read across chemical Rhodamine B (CAS no. 81 -88 -9) , biodegradation screening test is conducted for 4 weeks(J-CHECK, 20016) for read-across substance Rhodamine B (CAS: 81 -88 -9). Concentration of inoculum i.e, sludge was 30 mg/l and initial substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of read across substance is determined to be 0, 2 and 7% degradation by BOD, TOC removal and Uv-Vis parameter in 28 days. Thus, based on percentage degradation, read across substance Rhodamine B (CAS no. 81-88-9) is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical (study 1, 2 and 3) and of its closest read across substance (study 4, 5, 6 and 7 from peer reviewed journal and authoritative database), it can be concluded that the test substance C.I. Solvent Red 49 can be expected to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI) Suite (2017) prediction model was run to predict the half-life in water and sediment for the test compound C.I. Solvent Red 49 (CAS No. 509 -34 -2). If released in to the environment, 1.36% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 180 days (4320 hrs). The half-life (180 days estimated by EPI suite) indicates that the chemical is persistent in water and the exposure risk to aquatic animals is moderate to high whereas the half-life period of test chemical C.I. Solvent Red 49 in sediment is estimated to be 1620.833 days (38900 hrs). Based on this half-life value (1620.833 days), it indicates that the chemical C.I. Solvent Red 49 is persistent in sediment.

Biodegradation in soil

The half-life period of C.I. Solvent Red 49 (CAS No. 509 -34 -2) 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, 48.3% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of C.I. Solvent Red 49 in soil is estimated to be 360 days (8640 hrs). Based on this half-life value of C.I. Solvent Red 49, it is concluded that the chemical is persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to high.

On the basis of available information, the test substance C.I. Solvent Red 49 can be considered to be not readily biodegradable in nature.

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