2-tert-butylhydroquinone

Endpoint summary

Description of key information

Stability:

Hydrolysis:

Test chemical is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions. On the basis of this it is concluded that test chemical is not hydrolysable.

Biodegradation:

Biodegradation in water:

35-days Closed Bottle test following the OECD guideline 301 D was performed 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 as inoculum at concentartion 10E7 to 10E8 CFU/ml. 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 78.31 %. Degradation of Sodium Benzoate exceeds 49.39 % on 7 days & 75.3 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 1.27 mgO2/mg. ThOD was calculated as 2.4 mgO2/mg. Accordingly, the % degradation of the test item after 35 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be  52.91 %. Based on the results, the test item, under the test conditions, was considered to be ultimate inherently biodegradable in nature.

Biodegradation in water and sediments:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 11.5% 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 37.5  days (900 hrs). The half-life (37.5 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is low whereas the half-life period of test chemical in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 1.09 %), indicates that test chemical is not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemicalin soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 87.4 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is low .

Bioaccumulation:

Bioaccumulation: aquatic/sediments:

The bioaccumulation study in aquatic organisms was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation factor (BCF) value was calculated using a log Kow of 2.94 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 24 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is considered to be non-bioaccumulative in aquatic organisms.

Transport and distribution:

Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.1. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k (Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to functional similarity with the test substance and calibration graph prepared. The reference substances were Phenol, Xylene, Ethylbenzene, Toluene, Naphthalene, phenanthrene having Koc value ranging from 1.32 to 4.09. The Log Koc value of test chemical was determined to be 1.415 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

Additional information

Stability:

Hydrolysis:

Experimental studies for test chemical and its structurally similar read across chemical have been reviewed from authoritative database for hydrolysis endpoint and their results are summarized below.

 

In first study the test chemical is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions

 

In another study the Half life of hydrolysis of test chemical cannot be predicted and it is not relevant as there is no hydrolysable functional group.

 

By considering results of all the studies mentioned above it can be concluded that test chemical is non-hydrolysable in nature.

Biodegradation:

Biodegradation in water:

35-days Closed Bottle test following the OECD guideline 301 D was performed 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 as inoculum at concentartion 10E7 to 10E8 CFU/ml. 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 78.31 %. Degradation of Sodium Benzoate exceeds 49.39 % on 7 days & 75.3 on 14th day. The activity of the inoculum is thus verified and the test can be considered as valid. The BOD35 value of test chemical was observed to be 1.27 mgO2/mg. ThOD was calculated as 2.4 mgO2/mg. Accordingly, the % degradation of the test item after 35 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be  52.91 %. Based on the results, the test item, under the test conditions, was considered to be ultimate inherently biodegradable in nature.

Biodegradation in water and sediments:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 11.5% 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 37.5  days (900 hrs). The half-life (37.5 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is low whereas the half-life period of test chemical in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 1.09 %), indicates that test chemical is not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemicalin soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 87.4 % of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is low .

Bioaccumulation:

Bioaccumulation: aquatic/sediments:

Experimental studies for test chemical and its structurally similar read across chemical have been reviewed for bioaccumulation endpoint and their results are summarized below.

First study was reveiwed from authoritative database ( HSDB, 2017) in this study the the bioaccumulation factor (BCF) value was calculated using a log Kow of 2.94 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 24 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is considered to be non-bioaccumulative in aquatic organisms.

Another study was reviewed from authoritative database (J check) in this study the Bioaccumulation test was conducted for 6 weeks for determination the bioconcentration factor (BCF) of test chemical on test organism Cyprinus carpio. Recovery ratio : Test water : 1st concentration area : 90.1 %, 2nd concentration area : 79.6 %, Fish : 92.7 %, - Limit of detection : Fish : 0.

ppm And Nominal concentrations used in the study as - 1st Concentration area: 0.0001 mg/L, 2nd Concentration area : 0.00001 mg/L and Range finding study was carried out on Rice fish (Oryzias latipes) TLm(48h) 6.4 ppm(w/v), Rice fish (Oryzias latipes).Thus according to static Fish test the bioconcentration factor (BCF) for test chemical was determined according static fish test. The BCF value was observed to be 16-21 L/kg at dose concentration 0.0001 mg/L and 8.1-18 L/kg at dose concentration 0.00001 mg/L on test organism Cyprinus carpio during 6 weeks period.Therefore it is concluded that this test chemical is nonbioaccumulative.

In last study the BCF value of test chemical was estimated is 57 dimensionless by using log Kow of 3.50 and regression derived equation and it is far less than 2000 so it is concluded that this chemical is non bioaccumulative.

By considering results of all the studies mentioned above it can be concluded that test chemical is non-bioaccumulative in nature.

Transport and distribution:

Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.1. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k (Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to functional similarity with the test substance and calibration graph prepared. The reference substances were Phenol, Xylene, Ethylbenzene, Toluene, Naphthalene, phenanthrene having Koc value ranging from 1.32 to 4.09. The Log Koc value of test chemical was determined to be 1.415 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.