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Environmental fate & pathways

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Description of key information

Biodegradation in water

The ready biodegradability of Test chemical was determined by the OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test), EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test) and EPA OPPTS 835.3110 (Ready Biodegradability), respectively for 34 days. Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernant and resuspending in mineral medium) and kept aerobic until being used on the same day. Initial test substance concentration used in the study was 30 mg/l. Mineral medium was prepared by mixing 50 ml of solution A and 2000 ml deionised water, adding 5 ml of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide. The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon. Suspended solids concentration used in the study was 5.46 g/l diluted to 1.53 g/l dry matter. Sodium benzoate (100 mg/l) (purity min. 99.0%) was used as a reference substance for the study. Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days. Test chemical undergoes 75% biodegradation after 28 days in the test conditions. The 10 day window criterion is also fulfillled (15% biodegradation on day 2 and 69% biodegradation on day 12). 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. Thus, Test chemical should be regarded as readily biodegradable according to this test.

 

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound. If released in to the environment, 18.9% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of the chemical in water is estimated to be 15 days (360 hrs). The half-life (15 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 135 days (3240 hrs). However, as the percentage release of test chemical into sediment is less than 1 %( i.e., reported as 0.943%) indicates that test chemical is not persistent in sediments.

 

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, 2017). If released into the environment, 80 % 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 moderate to low. 

Additional information

Biodegradation in water

The ready biodegradability of Test chemical was determined by the OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test), EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test) and EPA OPPTS 835.3110 (Ready Biodegradability), respectively for 34 days. Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernant and resuspending in mineral medium) and kept aerobic until being used on the same day. Initial test substance concentration used in the study was 30 mg/l. Mineral medium was prepared by mixing 50 ml of solution A and 2000 ml deionised water, adding 5 ml of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide. The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon. Suspended solids concentration used in the study was 5.46 g/l diluted to 1.53 g/l dry matter. Sodium benzoate (100 mg/l) (purity min. 99.0%) was used as a reference substance for the study. Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days. Test chemical undergoes 75% biodegradation after 28 days in the test conditions. The 10 day window criterion is also fulfillled (15% biodegradation on day 2 and 69% biodegradation on day 12). 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. Thus, Test chemical should be regarded as readily biodegradable according to this test.

 

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound. If released in to the environment, 18.9% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of the chemical in water is estimated to be 15 days (360 hrs). The half-life (15 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 135 days (3240 hrs). However, as the percentage release of test chemical into sediment is less than 1 %( i.e., reported as 0.943%) indicates that test chemical is not persistent in sediments.

 

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, 2017). If released into the environment, 80 % 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 moderate to low.