Assessment of the biological and chemical availability of the freshly spiked and aged DDE in soil

The study compared the ability of various chemical methods (XAD, β-hydroxypropylcyclodextrin - HPCD) and solid phase micro-extraction (SPME)) to mimic earthworm uptake from two similar soils containing either spiked or aged p,p´-DDE, thus representing two extreme scenarios with regard to the length of pollutant-soil contact time and the way of contamination. The extent of bioaccumulation was assessed at fixed exposure periods (10 and 21 days) and at equilibrium derived from uptake curves by multiple-point comparison or kinetic modeling. The decision on the best chemical predictor of biological uptake differed. The degree of bioaccumulation at equilibrium was best predicted by XAD while HPCD rather reflected the extent of accumulation derived after 21 days when, however, steady-state was not reached for spiked p,p´-DDE. SPME seemed to underestimate the uptake of aged p,p´-DDE, probably of the fraction taken up via soil particles. Thus, the degree of predictability seems to be associated with the capability of the chemical method to mimic the complex earthworm uptake via skin and intestinal tract as well as with the quality of biological data where the insufficient length of exposure period appears to be the major concern. •The uptake kinetics of spiked and aged p,p´-DDE to earthworms/samplers was measured.•Three chemical methods were used to predict earthworm uptake.•Equilibrium was not reached within the OECD recommended 21 days for spiked p,p´-DDE.•SPME seems to underestimate the uptake of aged p,p´-DDE.•The best predictor of earthworm uptake seems to be the XAD method. Capsule: The poor prediction of biological uptake by chemical methods may result from the absence of kinetic measurements and application of short exposure periods.