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Environmental fate & pathways

Biodegradation in soil

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Description of key information

The partitioning of AKD in soil, sediment and sludge was calculated with EUSES using the maximum Koc value of 1*10E6 L/kg 

Key value for chemical safety assessment

Additional information

Experimental data on the biodegradation in soil of Alkyl Ketene Dimer are not available. Therefore, for the degradation rate the default value according to the TGD is estimated, assuming that no degradation takes place in the bound phase.


When the Koc of AKD was calculated using EPIWIN (v2.00) it was found to be 3.8E08 L/kg. Based on the maximum validated values in the EUSES program, the Koc is set to the maximum value of 1 * 106L/kg. This means that for risk assessment purposes, all partitioning coefficients for soil, sediment, suspended sediment and sludge are based on this maximum Koc value using the predominantly hydrophobics QSAR (EUSES).


Overview of the partitioning coefficients:


Kp soil = 2.104L/kg


Kp sed = 5.104L/kg


Kp susp = 1.105L/kg


 


The suggested half-life in bulk soil for a readily degradable substance with a Kpsoil in the range>10000-≤ 100000 l/kg is 30000 days.


Chemical hydrolysis of AKD is not influenced by adsorption onto solids and therefore the half live in the bulk soil should be based on the hydrolysis rate in the aqueous phase (Macalady and Wolfe, 1984; Burkhard and Guth, 1981). The hydrolysis half live in the aqueous phase at pH 8 and 25 °C ranges between 35 to 210 hours.