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Environmental fate & pathways

Biodegradation in soil

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Description of key information

A biodegradation study with read-across subtance C12-C16 ADBAC resulted in 64% biodegration in loam soil at Day 70 along with a DT50 value of 40 days

Key value for chemical safety assessment

Half-life in soil:
40 d
at the temperature of:
22 °C

Additional information

The biodegradation of the structurally similar C12 -C16 ADBAC was evaluated in loam. There were two treatments i.e., test substance and chemical blank control with three replicates. The test was carried out in biometers containing approximately 50 g dry weight equivalents of soil. The test substance in appropriate amounts of deionised water not exceeding that required for bringing the soils to 50 to 70% of the maximum moisture capacity. The amount of water to remoisturize 50 g of soil to approximately 60% of its maximum field capacity was determined from the data of the moisture content of the soil after air-drying and the maximum field moisture capacity. The soils were maintained at this moisture level for the duration of the test by the addition of deionised water, when necessary.

Loam was added to the Erlenmeyers of the biometer after the test solutions to facilitate moistening of the soils uniformly by capillary action. Test substance was added at a concentration of 10 mg carbon per 50 g soil, Approximately 50 g soil was in the Erlenmeyer flask of the biometer. The side tube contained 20 mL 0.2 M KOH for absorbing carbon dioxide produced by the microorganisms in the Erlenmeyer. The test was incubated at 22 ± 3°C. The test was run for approximately 90 d. The theoretical CO2 production of the test substance was calculated from the carbon content of the test substance.

The biodegradation was calculated as the ratio of experimental carbon dioxide production to theoretical carbon dioxide production [ThCO2P].

Benzyl C12-16 alkyl dimethyl ammonium chloride was 64% biodegraded in loam at Day 70. This percentage of the theoretical carbon dioxide production presumes completemineralisation. The DT50 is estimated 40 days (van Ginkel and Pomper, 1994).