Application of the AhR-CALUX and ER-CALUX screening bioassays for accurate detection and relative quantitation of dioxin-like and estrogen-like compounds from soil and sediment

Assessing the environmental contamination for endocrine disrupting chemicals (EDCs) is a large task and an increasing concern for human and wildlife populations and ecosystems. Traditional analytical practices for the purpose of evaluating environmental contamination are time consuming and expensive, screening such samples for the purpose of evaluating levels of contamination can save time and money. In the following studies the functionality of the AhR-CALUX and ER-CALUX when used as a screening tool is shown to be improved by the most recent updates to the WHO TEF values and by utilizing the CALUX REP values when attempting to determine biological impact from analytical data. We found improved correlation between CALUX BEQ values and the 2006 WHO TEF values over the WHO 1998 WHO TEF values an even better correlation was determined between the CALUX BEQ values and TEQ values when the CALUX REP values were used for calculation.The ER-CALUX and the AhR-CALUX were used to evaluate crude sediment extracts during a two year multidisciplinary study designed to establish estuarian ecosystem health. Induction levels from polar and non-polar extracts from subsamples of the same sediment were evaluated to first identify a hierarchy of contamination between estuary sites during the first year and the level of contamination with in an estuary the second year. Stege Marsh on the eastern side of the San Francisco Bay was the site chosen for the second year study. The second year study data showed a wide variation in the levels of induction as a result of both estrogenic and AhR ligand contamination most likely due to mixing from resuspension and sedimentation. Our data will be combined in Part 2 of this study with biological data from a newly determined sentinel species which will further our understanding of ecosystem impact from EDCs.Observations of induction curves from crude extracts can typically exhibit maximum levels of induction greater than that induced from 1 nM TCDD, superinduction. However, we report here for the first time superinduction of the AhR-CALUX bioassay by samples that have been processed through a cleanup procedure and fractionated into Dioxin-like HAHs and PCB-like compounds. As a result of recognizing the superinduction phenomenon the calculation of BEQ values was also reevaluated to prevent over estimation of sample potency. Establishing a full dose curve and using the appropriate EC50 values from both the TCDD standard curve and the sample extract induction curve showed that the range of BEQ values is minimized from being nearly 10 fold greater than the TEQ value to within reasonable limits of +/-30% for most cleaned up sample extracts.This body of work advances and expands our understanding and knowledge and application of the CALUX bioassays with regards to screening environmental sample extracts for the presence of AhR- and ER- ligands, with regard specifically to screening for DL-HAHs.