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Description of key information

Biodegradation in water:

The Ready Biodegradability of test chemical was determined by the Manometric respirometry. Test conducted in accordance with OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test). A measured volume of inoculated mineral medium containing a known concentration 30 mg/l of test substance as the nominal sole source of organic carbon was stirred in a closed flask at a constant  temperature (± 1 °C) for up to 28 days. Evolved carbon dioxide was absorbed in sodium hydroxide pellets. Fresh activated sludge from a biological wastewater treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used. The consumption of oxygen was determined by measuring the pressure drop in the respirometer flask. The Biological Oxygen Demand (BOD), amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel)  was expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide,  hydrogen to water and nitrogen to ammonium, nitrite or nitrate). Test chemical undergoes 88 % biodegradation after 28 days (87% after 62 days) in the test conditions. The 10-day window criterion was also fulfilled (20% biodegradation on day 1 and 77% on day 11). Thus, based on the % degradation of test chemical, test chemical considers to be readily biodegradable. Test chemical did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

 

 

Biodegradation in water:

Estimation Programs Interface (EPI Suite) prediction model was run to predict the half-life in water for the test chemical. If released into the environment, 24.8 % 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 was estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical was not persistent in water and the exposure risk to aquatic animals is low.

 

Biodegradation in sediment:

Estimation Programs Interface (EPI Suite) prediction model was run to predict the half-life in sediment for the test chemical. The half-life period of test chemical in sediment was estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.406 %), indicates that test chemical was not persistent in sediment.

 

Biodegradation in soil:

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite). If released into the environment, 72.6 % 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 30 days (720 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.

Additional information

Biodegradation in water:

Two different experimental studies from different sources have been reviewed to determine biodegradability of test chemical and their results are summarized below.

The Ready Biodegradability of test chemical was determined by the Manometric respirometry. Test conducted in accordance with OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test). A measured volume of inoculated mineral medium containing a known concentration 30 mg/l of test substance as the nominal sole source of organic carbon was stirred in a closed flask at a constant  temperature (± 1 °C) for up to 28 days. Evolved carbon dioxide was absorbed in sodium hydroxide pellets. Fresh activated sludge from a biological wastewater treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used. The consumption of oxygen was determined by measuring the pressure drop in the respirometer flask. The Biological Oxygen Demand (BOD), amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel)  was expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide,  hydrogen to water and nitrogen to ammonium, nitrite or nitrate). Test chemical undergoes 88 % biodegradation after 28 days (87% after 62 days) in the test conditions. The 10-day window criterion was also fulfilled (20% biodegradation on day 1 and 77% on day 11). Thus, based on the % degradation of test chemical, test chemical considers to be readily biodegradable. Test chemical did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

 

Above study further supported by the second study from experimental source. 28-days Manometric respirometry test was conducted following the OECD guideline 301F to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20± 1°C. Mixture of domestic wastewater, surface soil and soil samples was used as a test inoculum for the study. This inoculum was collected and were mixed to get diluted suspension. The inoculum was kept aerobic until being used for experiment by supplying organic and inorganic sources required by micro flora to sustain at controlled laboratory conditions.  This gave the bacterial count as 10e7 to 10e8 CFU/ml. At the regular interval microbial plating was also performed on agar to confirm the vitality and CFU count of microorganism. OECD mineral medium was used for the study. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 100 mg/L, while that of inoculum was 10 ml/l. 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 (Sodium Benzoate) was also calculated using BOD & ThOD and was determined to be 75.80 %. The mean BOD values (mg O2/l) in control on 28th day was 37.3 mg O2/l, thereby fulfilling the control validity criteria (i.e., The oxygen consumption of the inoculum blank is normally 20-30 mg O2/l and should not be greater than 60 mg/l in 28 days). Degradation of Sodium Benzoate exceeds 60 % after 14 days. The activity of the inoculums is thus verified, and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.967 mgO2/mg. ThOD was calculated as 2.424 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was determined to be 81.15%.Based on the results, the test item, under the test conditions, was determined to be readily-Biodegradable at 20 ± 1°C over a period of 28 days.

Thus, based on the above both studies, test chemical consider to be readily biodegradation in water.

 

Biodegradation in water:

Estimation Programs Interface (EPI Suite) prediction model was run to predict the half-life in water for the test chemical. If released into the environment, 24.8 % 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 was estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical was not persistent in water and the exposure risk to aquatic animals is low.

 

Biodegradation in sediment:

Estimation Programs Interface (EPI Suite) prediction model was run to predict the half-life in sediment for the test chemical. The half-life period of test chemical in sediment was estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.406 %), indicates that test chemical was not persistent in sediment.

 

Biodegradation in soil:

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite). If released into the environment, 72.6 % 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 30 days (720 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.