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Determination of polyoxymethylene (POM) water partition coefficients for DDT and its degradation products, with inter-laboratory comparison of the passive sampling methodology and bioaccumulation in earthworm (Eisenia fetida)
Anja Enell 
, Stephanie Casey , Ayan Au Musse , Sarah Josefsson , Johannes Kikuchi-McIntosh, Greta Nilén , Karin Wiberg, Anna-Karin Dahlberg , Maria Larsson
Abstract
Rationale: The insecticide dichlorodiphenyltrichloroethane (DDT) and its degradation products are persistent organic pollutants that pose significant environmental risks due to their persistence and bioaccumulation in ecosystems. Accurate quantification of DDX bioavailability in soil systems is crucial for effective land management and risk assessment. Methodology: This study utilized equilibrium passive sampling with polyoxymethylene (POM) to determine the bioavailability of DDX in soil. The sorption dynamics of ten DDX compounds were investigated (p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD, p,p'-DDE, o,p'-DDE, p,p'-dichlorodiphenylmethane (p,p'-DDM), p,p'-dichlorobenzophenone (p,p'-DBP), 1-chloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-DDMU) and dicofol), and their POM-water partition coefficients (KPOM) were determined. The study involved interlaboratory comparisons, using soils from nine historically contaminated sites and ecotoxicology assessments (mortality, reproduction and bioaccumulation in earthworms Eisenia fetida) to validate the POM method. Results: The KPOM values for nine of the ten DDX compounds were successfully determined, allowing for accurate quantification of freely dissolved pore water concentrations of DDX in historically contaminated soils. The interlaboratory study highlighted important considerations in extraction and GC-MS analysis, and the ecotoxicology study demonstrated the potential of POM passive sampling as a reliable tool for assessing DDX bioavailability (bioaccumulation in Eisenia fetida). Discussion: The POM method proved to be a robust and reliable approach for quantifying freely dissolved DDX, with implications for improving the accuracy of risk assessments and guiding sustainable land management practices. The study also highlighted the need for careful consideration of analytical challenges, such as the potential degradation of DDX compounds during GC analysis, to ensure accurate quantification.
EN25011 Accepted 02 May 2025
© CSIRO 2025
