Assessment of DDT and its Metabolites Bioaccessibility in Historically Contaminated Soils Using Unfed and Fed in Vitro Methods.

Bioaccessibility of hydrophobic organic contaminants (HOCs) from unintentional ingestion of soil is increasingly assessed with in vitro gastrointestinal models incorporating a sorption sink. In this study, the bioaccessibility of DDTs in contaminated soils (n = 11) was determined using "unfed" unified bioaccessibility method (UBM) and fed organic estimation human simulation test (FOREhST) with/without Tenax as an absorbent. By adding Tenax, the bioaccessibility of DDTs determined using UBM was significantly increased from 4.9-30.6% to 31.6-86.0%. In contrast, the bioaccessibility of DDTs determined using FOREhST without/with Tenax were similar with values of 20.0-60.9% vs 31.5-47.6%, implying that the influence of food components on the absorption efficiency of the sink should not be overlooked. Much high fraction of DDTs (bioaccessibility: 11.7-24.8%) remained in FOREhST supernatant after Tenax collection, suggesting that prediction of bioavailability through bioaccessibility obtained by absorbent needs to be treated with caution when bioaccessibility is determined using a "fed state" in vitro method.