Disodium 2-(2,4,5,7-tetrabromo-6-oxido-3-oxoxanthen-9-yl)benzoate

Endpoint summary

Description of key information

Biodegradation in water

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item (Experimental study report., 2018). The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32ml/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 75.3%. Degradation of Sodium Benzoate exceeds 46.38% on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.87 mgO2/mg. ThOD was calculated as 0.92 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 94.56%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

Additional information

Biodegradation in water

Various experimental studies of the test chemical were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from study report (2018), 28-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 for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32ml/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 75.3%. Degradation of Sodium Benzoate exceeds 46.38% on 7 days & 61.44% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 0.87 mgO2/mg. ThOD was calculated as 0.92 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 94.56%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

 

Another biodegradation study was carried out for 42 days for evaluating the percentage biodegradation of the test chemical using modified OECD Guideline 302B (U. Pagga et. al., 1986). Activated sludge was used as a test inoculum. The sources of the activated sludge were treatment plants conveniently located to the laboratories carrying out the test. These treatment plants received communal and/or industrial wastewater. Concentration of inoculum i.e, activated sludge used was 0.5 g/l and initial test substance conc. used in the study was 100 mg/l. Analytical methods involve the measurement of extinction at absorption maximum 412 nm and DOC (dissolved organic carbon). The percentage degradation of the test chemical was determined to be -3% by using DOC removal parameter in 42 days. Thus, based on percentage degradation, the chemical was considered to be not readily biodegradable in nature.

 

For the test chemical, biodegradation study was carried out for evaluating the percentage biodegradation of the test chemical (Laura Carmen Apostol et. al., 2012). Anaerobic granular sludge (non-adapted) collected from wastewater treatment plant of ‘‘Central de Cervejas’’, Vialonga, Portugal was used as a test inoculum for the study. The study was performed under anaerobic conditions at a temperature of 37°C and pH7 ± 0.2, respectively. The volatile suspended solids content of the biomass was determined as 0.0943 g VSS g-1.120 ml serum bottles was used as a test vessel for the study. Batch assays were conducted in 120 mL serum bottles with butyl rubber stopper, containing the biomass, 0.94 g VSS L-1, the substrate and macronutrients in a total volume of 50 mL of medium, that was buffered at a pH of 7±0.2 with NaHCO3 (2.5 g L-1).The headspace of the serum bottles was flushed with the N2:CO2 (80/20 v/v) and pre-incubation of the sludge was done overnight at 37°C, in a rotary shaker at 120 rpm. As macronutrients, 2.8 g/l NH4Cl, 2.5 g/LKH2PO4, 1 g/l MgSO4.7H2O and 0.06 g/L CaCl2 were added. Volatile fatty acids (VFAs: acetic, propionic, and butyric acid, 1:10:10) were supplemented as electron source for the reduction (2 g COD L-1). Test chemical conc. used for the study was207.55 mg/l (0.3 mM).The serum bottles were further incubated at 37°C in a rotary shaker at 120 rpm for 1 day. All the experiments were performed in triplicates.Color decrease was monitored spectrophotometrically in a 96-well plate reader (ELISA BIO-TEK, Izasa). At select intervals, samples were withdrawn (300lL), centrifuged at 5000 rpm for 10 min to remove the biomass and/orACand diluted, with the same buffer as of the reaction, to obtain less than one absorbance unit (AU), due to the high absorbance of the dye, even at low concentrations. The visible spectra (300–900 nm) were recorded and dye concentration calculated atλmax. HPLC analyses were also performed in a HPLC (JASCO AS-2057 Plus) equipped with a DAD (Diode Array Detector) detector. A C18 reverse phase Nucleodur MNC18 (25094.0 mm, 5lM particle size and pore of 100 A ° from Machenerey-Nagel, Switzerland) column was used. The following solvent systems were used as mobile phase: solvent A (ACN) and solvent B (Sodium acetate buffer, pH 5.3). Compounds were eluted at a flow rate of 0.7 mL min-1 and at room temperature, with a linear gradient of mobile phase from 10 to 100 % of solvent A, over 15 min, followed by isocratic condition with 100% of solvent A over 10 min. Compounds elution was monitored atλmax of each dye and 230 nm. First-order reduction rate constants were calculated in OriginPro 6.1 software. The percentage decolorization of the test chemical was determined to be 7% after 1 days. Thus, based on percentage degradation, test chemical was considered to be not readily biodegradable in nature.

 

Second study results from peer reviewed journal indicate the chemical to be not readily biodegradable which was not performed as per the standard guideline and in third study, duration of the study was very less (i.e, 1 day), so considering the experimental study result from study report (K1) performed as per the standard OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test), it can be concluded that the test chemical is readily biodegradable in nature.