We just published a study in Ecotoxicology that has been ongoing for years. Here we are interested understanding the effect of repeated exposure to contamination during sensitive stages of development during multiple generations. Such exposure could potentially affect the proper development and thus extend to potential population-wide outcomes. In the great lakes we observe this with the exposure and effects of persistent, bioaccumulative and toxic (PBT) compounds, which are pretty plentiful , on local biota. Previous work found many classes of these compounds (PAHs, PCBs, Dioxins/furans) distributed and bioavailable to tree swallow (Tachycineta bicolor) nestlings. The route of exposure is potentially through the diet of nestlings (insects that may spend time in the contaminated sediment of the lake) or through maternal depuration. The tree swallow is a bird that has strong natal homing and is ubiquitously distributed around the great lakes. Studies coming from the Matson and Custer/Custer groups have shown these to be available in the tissue of developing nestlings and has shown that there are up-regulated biomarkers of effect, associated with increasing body burden. In this study, we expand this study to include a time-series of 5 consecutive years (generations) and 27 sites with various level of total and class specific concentrations. We study the associations between biomarkers of exposure and effect and the body burden in nestlings from those locations and years. Check it out! We appreciate any comments!