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Environmental fate & pathways

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Description of key information

Hydrolysis

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the half-life value of the test chemical was not known and was reported to be hydrolytically stable. Thus, based on this, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water

42-days Closed Bottle test following the OECD guideline 301 D 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 item and reference item. Polyseed were used for this study. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 107 to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. The concentration of test and reference item (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 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 BOD42 value of test chemical was observed to be 0.62 mgO2/mg. ThOD was calculated as 2.31 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 26.83%. Based on the results, the test item, under the test conditions, was considered to be primary inherently biodegradable in nature.

Bioaccumulation: aquatic / sediment

BCFBAF model of Estimation Programs Interface was used to predict the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 7541 L/kg whole body w.w (at 25 deg C) which exceeds the bio concentration threshold of 5000, indicating that the test chemical is  expected to be very bioaccumulate in the food chain.

Adsorption / desorption

KOCWIN model of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical. The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 698300000 L/kg (log Koc=8.8441) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

Additional information

Hydrolysis

Data available for the test chemical has been reviewed to determine the half-life of hydrolysis as a function of pH. The studies are as mentioned below:

 

The half-life of the test chemical was determined. Although half-life value of test chemical was not known, but it was noted that chemical is not susceptible to hydrolysis and thus it was reported to be hydrolytically stable. On the basis of this, test chemical is considered to be not hydrolysable.

 

In an another study, the half-life of the test chemical was determined. Although the hydrolysis half-life value of test chemical was not known and as it has only 3-membered aromatic rings associated with its structure that is generally resistant to hydrolysis. Thus, test chemical was reported to be hydrolytically stable.

 

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the half-life value of the test chemical was not known and was reported to be hydrolytically stable. Thus, based on this, it can be concluded that the test chemical is not hydrolysable in water.

Biodegradation in water

42-days Closed Bottle test following the OECD guideline 301 D 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 item and reference item. Polyseed were used for this study. 1 polyseed capsule were added in 500 ml D.I water and then stirred for 1 hour for proper mixing and functioning of inoculum. This gave the bacterial count as 107 to 108 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. The concentration of test and reference item (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 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 BOD42 value of test chemical was observed to be 0.62 mgO2/mg. ThOD was calculated as 2.31 mgO2/mg. Accordingly, the % degradation of the test item after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 26.83%. Based on the results, the test item, under the test conditions, was considered to be primary inherently biodegradable in nature.

Bioaccumulation: aquatic / sediment

Various predicted data of the test chemical were reviewed for the bioaccumulation end point which are summarized as below:

 

In a prediction done using the BCFBAF Program of Estimation Programs Interface was used to predict the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 7541 L/kg whole body w.w (at 25 deg C) which exceeds the bio concentration threshold of 5000, indicating that the test chemical is expected to be very bioaccumulate in the food chain.

 

In an another prediction done by using Bio-concentration Factor module (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)), the Bio-concentration Factor of the test chemical was estimated to be 10337, 308937, 1171078, 1439508, 1471549, 1474815, 1475142, 1475174 and 1475177 at pH range 0, 1, 2, 3, 4, 5, 6, 7 and 8-14, respectively. This value indicates that the test chemical was considered to be very bioaccumulative in aquatic organisms.

 

Another predicted data was estimated using SciFinder database (American Chemical Society (ACS), 2017) for predicting the bioconcentration factor (BCF) of test chemical. The bioconcentration factor (BCF) of test chemical was estimated to be 1330, 5880, 7450, 7640 and 7660 at pH range 1, 2, 3, 4 and 5-10 respectively (at 25 deg C) which exceeds the bio concentration threshold of 5000 (at pH 7.0), indicating that the test chemical is expected to be very bioaccumulate in the food chain.

 

On the basis of above results for test chemical (from modelling databases, 2017), it can be concluded that the BCF value of test substance ranges from7541 to 1475174 (at pH 7.0), which exceeds the bioconcentration threshold of 5000, indicating that the test chemical is expected to be very bioaccumulate in the food chain.

Adsorption / desorption

Various predicted data of the test chemical were reviewed for the adsorption end point which are summarized as below:

 

In aprediction done using theKOCWIN Programof Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical. The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 698300000 L/kg (log Koc=8.8441) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using Adsorption Coefficient module program as Koc 6350, 189780, 719394, 884291, 903974, 905980, 906181, 906201 and 906203 at pH range 0, 1, 2, 3, 4, 5, 6, 7 and 8-14, respectively (logKoc ranges from 3.8 ± 1.0 to 6.0 ± 1.0) (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)). The logKoc value (at pH 7.0) indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

Additional soil adsorption coefficient i.e Koc value of test chemicalwas estimated using the SciFinder database (2017).The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 3650, 16100, 20400, 20900 and 21000 at pH range 1, 2, 3, 4 and 5-10, respectively (at 25 deg C) (logKoc value ranges from 3.562 to 4.322). This Koc value indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

For the test chemical, adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical (HSDB and PubChem, 2017). The adsorption coefficient (Koc) value was calculated using an experimental water solubility of 0.0179 mg/l and a regression derived equation. The adsorption coefficient (Koc) value of test substance was estimated to be 40000 (Log Koc = 4.6). This Koc value indicates that the test substance has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

On the basis of above overall results for test chemical, it can be concluded that the log Koc value of test chemical was estimated to be ranges from 3.562 to 8.8441, respectively, indicating that the test chemicalhas a strong to very strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.