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Biodegradation in water: screening tests

The predicted data for the test compound Pyrazolone T (CAS no. 118-47-8) and study of its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

Biodegradation in water ability was predicted (SSS QSAR prediction model, 2016) for the test substance Pyrazolone T (CAS no. 118-47-8) using the SSS QSAR prediction model. The ready biodegradability of the test substancePyrazolone Twas estimated as 15.81% in 28 days by using CO2 evolution parameter. This result indicates that Pyrazolone Twas estimated to be not readily biodegradable in water.

 

Estimation Programs Interface Suite (EPI suite) was run to predict the biodegradation potential of the test compoundPyrazolone T(CAS no. 118-47-8). The screening test inherent to the biodegradability of the substance was calculated using the software BIOWIN v4.10. The results indicate thatPyrazolone Tis not expected to be readily biodegradable in nature.

 

Microbial decomposition of test chemical Food yellow 4 was carried out for 10 days (Yasuhide TONOGAI, 1978). The biodegradation of chemical was determined by 3 methods under aerobic conditions: Aerobic decomposition of dyes with sludge, Oxygen uptake and BOD determination. During 10 days of the aerobic experiment, the absorbance of dye solution was measured once day for 10 days. Only 20% decomposition of test chemical was obtained in10 days. 3.82 O2 mg/hg – sludge oxygen uptake was obtained in 5 –hrs test and the dissolved oxygen contents on the 5th day were essentially the same to initial ones. The low reactivity of aerobic sludge towards dyes was confirmed. Based on the results obtained from the aerobic degradation assay, Warburg method and BOD determination, it can be concluded that tartrazine is not expected to be readily biodegradable under aerobic conditions.

 

Biodegradation screening test (J-CHECK, 2016) was conducted for 28 days (4 weeks) for evaluating the percentage biodegradability of the test substance Edaravone. 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 found to be 0% by BOD, 2% by TOC and 28% by HPLC. Thus, the substance Edaravone is not expected to be not readily biodegradable in water.

 

On the basis of above results for target and read across substance, it can be concluded that the test substance is not expected to be readily biodegradable in nature.

Biodegradation in water and sediment: simulation tests

Estimation Programs Interface (EPI) Suite (2016) prediction model was run to predict the half-life in water and sediment for the test compound Pyrazolone T (CAS no. 118 -47 -8). Half-life of Pyrazolone T in water is estimated to be 15 days (360 hrs) while in sediment it is 134 days (3240 hrs). Based on these half-life value of Pyrazolone T, it is concluded that the chemical is not persistent in water but persistent in sediment.

Biodegradation in soil

Based on EPI prediction Level III Fugacity Model (EPI suite, 2016), the estimated half life period of Pyrazolone T in soil was obtained to be 30 days (720 hrs). Based on this half life value of Pyrazolone T, it is concluded that the chemical is not persistent in the soil environment.

On the basis of available information for the target substance, the test substance can be considered as not readily biodegradable in nature