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Biodegradation in water:

Biodegradability of test chemical Trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate

(CAS no. 20298 -05 -9) was estimated by using OECD QSAR tool box v3.3 considering eight closest read across chemical with log Kow as primary descriptor. Percent biodegradation of test chemical Trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate was estimated to be 0.75 by considering BOD as parameter  and microorganisms as inoculum in 28 days. On the basis of percent biodegradability value it is concluded that this test chemical is not readily biodegradable.

Additional information

Biodegradation in water:

 Predicted data for target chemical Trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate(CAS no. 20298 -05 -9) and experimental studies for its read across chemical are summarized below for biodegradation endpoint.

 

In first weight of evidence study the biodegradability of test chemical Trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate(CAS no. 20298 -05 -9) was estimated by using OECD QSAR tool box v3.3 considering eight closest read across chemical with log Kow as primary descriptor. Percent biodegradation of test chemical Trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate was estimated to be 0.75 by considering BOD as parameter  and microorganisms as inoculum in 28 days. On the basis of percent biodegradability value it is concluded that this test chemical is not readily biodegradable.

 

Another weight of evidence study was done from Chemosphere Vol 22 pp 107-119 1991 by Glenn M Shaul, Thomas J Holdsworth, Clyde R. Dempsey, and Kenneth A. Dostal in this study the Biodegradability of read across chemical trisodium 5-hydroxy-1-(4-sulphophenyl)-4-(4-sulphophenylazo)pyrazole-3-carboxylate (Acid yellow 23) was determined by anlysing percent recovery of test material. This read across material is dye and inoculums used for biodegradation was obtained from Screened raw waste water from greater Cincinnati Mill Creek sewage treatment plant was used as influent (INF) to three pilot scale activated sludge biological treatment systems (Two experimental and one control). Each system consists of primary clarifier, complete mix aeration basin and secondary clarifier. Influent was spiked with test material at concentration of 1 mg/L and 5 mg/L. Then Dye analytical studies were conducted by purified dye compound in organic free influent waste water and mixed liquor. Then influent, primary influent filtrate was passed through column packed with resin. The filter paper and resin were soaked in an ammonia – acetonitrile solution and then soxhlet extracted with ammonia – acetonitrile. The extract was concentrated and brought upto 50 ml volumn with methanol/dimethyl formamaide solution. All extracted samples were analyzed by HPLC with ultraviolet detector.  Percent recovery determined was 107 % in low spiked and 103 % in high spiked. On the basis of percent recovery value biodegradation of dye was negligible i.e., 0%. Percent biodegradation of read across chemical trisodium 5-hydroxy-1-(4-sulphophenyl)-4-(4-sulphophenylazo)pyrazole-3-carboxylatewas observed to be 0.0 % by test material analysis by HPLC parameter. On the basis of percent degradation it is concluded that this test material is not readily biodegradable.

 

Next weight of evidence study was done from The Journal of Toxicological Sciences, Vol.3 , 193 -204, (1978) by Yasuhide TONOGAI, Masahiro IWAIDA, Masatomo TATI, Youki OsE and Takahiko SATO . The aim of the study was to estimate the microbial decomposition of read across chemical Food yellow 4 dye. 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 in a day for 10 days. 20% decomposition of read across chemical was obtained in 10 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 this read across is not readily biodegradable under aerobic conditions.

 

Next study was also conducted for read across from the Journal of Toxicological Sciences, Vol.3 , 193 -204, (1978) in this study the Biodegradability of read across chemical Sodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo) benzenesulphonate (Acid Red 151) was determined by analyzing percent recovery of test material. This test material is dye and inoculums used for biodegradation was obtained from Screened raw waste water from greater Cincinnati Mill Creek sewage treatment plant was used as influent (INF) to three pilot scale activated sludge biological treatment systems (Two experimental and one control). Each system consists of primary clarifier, complete mix aeration basin and secondary clarifier. Influent was spiked with test material at concentration of 1 mg/L and 5 mg/L. Then Dye analytical studies were conducted by purified dye compound in organic free influent waste water and mixed liquor. Then influent, primary influent filtrate was passed through column packed with resin. The filter paper and resin were soaked in an ammonia – acetonitrile solution and then soxhlet extracted with ammonia – acetonitrile. The extract was concentrated and brought upto 50 ml volumn with methanol/dimethyl formamaide solution. All extracted samples were analyzed by HPLC with ultraviolet detector. Percent recovery and Percent adsorbed of read across chemical Sodium 4-(4-(2-hydroxynaphthalenylazo)phenylazo)benzenesulphonatewas observed was 82% and 50 % in low spike of test chemical and 70 % and 58% at high spike of read across chemical respectively. On the basis of percent recovery value biodegradation of dye was 9.0 % at low spike and 15 % at high spike of read across chemical. On the basis of percent degradation it is concluded that this read across material is not readily biodegradable.

 

Last weight of evidence study was done from authoritative database (HSDB, 2017) in this study the read across chemical disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate (CAS no. 2783-94-0) showed 0.0% biodegradation by considering BOD as parameter in 5 days, and by taking sewage as inoculums. So it is concluded that read across chemical disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate is not readily biodegradable.

 

On the basis of all the studies mentioned above it can be concluded that test chemical Trisodium 2-[(E)-2-(3-methyl-5-oxo-1-{4-[2-(sulfonatooxy)ethanesulfonyl]phenyl}-4,5-dihydro-1H-pyrazol-4-yl)diazen-1-yl]naphthalene-1,5-disulfonate  (CAS No. 20298-05-9) is expected to be not readily biodegradable.