5-nitroisophthalic acid

Endpoint summary

Description of key information

Biodegradation in water:

By applying weight of evidence approach the percent biodegradation of test chemical is expected to be in range from 73.33% to 96.8% in aerobic condition and in 28 days. On the basis of this percent biodegradability test chemical is considered to be readily biodegradable.

Additional information

Biodegradation in water:

Biodegradability of test chemical was determined by using weight of evidence approach by using different experimental data from its structurally similar read across analogues and their results are summarized below

 

In first study the Closed Bottle test following the OECD guideline 301 D was conducted to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C. The test system included control, test chemical and reference chemical. Polyseed were used as inoculum. The concentration of test and reference chemical (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 chemical was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test chemical and reference chemical. The % degradation of procedure control (reference chemical) 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 0.77 mgO2/mg. ThOD was calculated as 1.05 mgO2/mg. Accordingly, the % degradation of the test chemical after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 73.33%. Based on the results, the test chemical, under the test conditions, was considered to be readily biodegradable in nature.

 

Another study was reviewed from journal Water Research, 1976 in this a batch test in an open system was conducted for 20 days for evaluating the biodegradability of test chemical. Adapted activated sludge was used as a test inoculum obtained from a sewage plant is cultivated in a1000ml volumetric cylinder. The mixture is aerated with pressure air. Every day 200 ml of the mixture is driven off so that the sludge age is 5 days. After driving off the 200ml of the mixture aeration is interrupted, and after sedimentation ca.600ml of the liquid phase is driven off. The residue (200 ml of the thickened activated sludge) is diluted with tap water to the volume ofca.800 ml and 600 mg/l of starch or glucose, 600 mg/l of peptone, 25 ml of a phosphate buffer pH 7.2, and the solution of the tested compound are added. Then the mixture in the cylinder is made up to 1000ml with tap water and aerated for 23 h (the recirculation ratio is 0-25). After this period the procedure is repeated. Test chemical conc. used for the study was 200 mg/l based on COD. To 1000-1500ml of the biological medium such amount of the solution of the substance tested is added that the initial COD is 200 mg/l. Then such an amount of the adapted activated sludge, washed and thickened by sedimentation, is dosed to the medium that the concentration of the dry matter is 100 mg/l. simultaneously, a blank test is prepared. The beaker is placed in a dark room with a roughly 3 constant temperature of 20±3°C on an electromagnetic stirrer and a pH of 7.2 for 120 hrs. The initial value of COD or organic carbon of the liquid phase are determined. Samples filtered or centrifuged before analysis, are taken at suitable intervals. The decrease of the tested substance in the liquid phase is evaluated by determining COD or organic carbon. The results are compared with those of a blank test and standard compound decomposition. With the degree of degradation also the average specific rate of degradation is determined, expressed in terms of mg COD (or organic carbon) removed by a gram of dry matter of the activated sludge per hour. The percentage degradation of test chemical was determined to be 96.8% by using COD removal parameter in < 20 days. Thus, based on percentage degradation, test chemical was considered to be readily biodegradable in nature.

 

By considering results of both the studies mentioned above and applying weight of evidence approach the percent biodegradation of test chemical is expected to be in range from 73.33% to 96.8% in aerobic condition and in 28 days. On the basis of this percent biodegradability test chemical is considered to be readily biodegradable.