Article pubs.acs.org/est
Assessment of DDT Relative Bioavailability and Bioaccessibility in Historically Contaminated Soils Using an in Vivo Mouse Model and Fed and Unfed Batch in Vitro Assays Euan Smith,*,†,‡ John Weber,†,‡ Allan Rofe,§ Dorota Gancarz,§ Ravi Naidu,†,‡ and Albert L. Juhasz†,‡ †
Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Mawson Lakes, SA 5095, Australia § Veterinary Services Division, Institute of Medical and Veterinary Science, Gilles Plains, SA 5086, Australia ‡
ABSTRACT: In this study, DDTr (DDTr = DDT + DDD + DDE) relative bioavailability in historically contaminated soils (n = 7) was assessed using an in vivo mouse model. Soils or reference materials were administered to mice daily over a 7 day exposure period with bioavailability determined using DDTr accumulation in adipose, kidney, or liver tissues. Depending on the target tissue used for its calculation, some variability in DDTr relative bioavailability was observed; however, it did not exceed 25% (range 2−25%). When DDTr bioaccessibility was determined using organic physiologically based extraction test (Org-PBET), unified BARGE method (UBM), and fed organic estimation human simulation test (FOREhST) in vitro assays, bioaccessibility was less than 4% irrespective of the assay utilized and the concentration of DDTr in the contaminated soil. Pearson correlations demonstrate a poor relationship between DDTr relative bioavailability and DDTr bioaccessibility (0.47, 0.38, and 0.28, respectively), illustrating the limitations of the static in vitro methods for predicting the dynamic processes of the mammalian digestive system for this hydrophobic organic contaminant.
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INTRODUCTION Dichlorodiphenyltrichloroethane (DDT) was one of the original 12 persistent organic pollutants that the Stockholm Convention seeked to ban globally.1 Many countries have restricted or banned the use of DDT in agriculture, but high concentrations of DDT still persist in the environments where it was used historically. Extensive use of DDT as an insecticide in agriculture has resulted in the contamination of over 1000 former cattle dip sites in northeastern New South Wales, Australia, with DDT concentrations ranging from
