Accurately determining a person's exposures to environmental chemicals is a central challenge to evaluating potential health consequences of contaminants. Quantifying environmental contaminant bioavailability is one fundamental nexus for characterizing environmental exposure. Single-time collection grab samples generates an impossible number of complex samples to analyze analytically that are also too dilute to reasonable assess biological activity. Analysis of trapped local aquatic organisms such as fish or shellfish can be used to assess persistent bioaccumulative toxicants, but suffer from many limitations: metabolism, difficulties in obtaining samples, necessary destructive sampling and inherent biological and physiological variability, nor does one know how long the organism was exposed to the toxicants. Many similar challenges exist with the analysis of biomarkers in epidemiological studies of environment and disease. To overcome these issues, we have further developed passive sampling devices (PSDs) for water, air, sediment and personal monitoring now used at multiple Superfund sites, in the Gulf of Mexico as part of the DeepWater Horizon oil spill, and in several western Africa countries as part of an on-going United Nations sponsored pesticide-monitoring project. Membranes in PSDs sequester thousands of bioavailable chemicals including previously unmonitored chemicals. The micro-porous and hydrophobic nature of the membranes was chosen to mimic both chemical and physical selective processes that affect uptake by organisms. We now seamlessly and routinely use the PSD extracts from water exposures in the embryonic zebrafish and Ames assay models. Because contaminants sequestered by such membranes are recovered for use in analytical and bioassays, we are able to combine continuous sampling with biological endpoints that will enhance our ability to assess effectiveness and mitigation of toxicity. The design, calibration, use and comparison of PSD membrane technologies will be discussed.
Two applications of the PSD will be presented; the first will illustrate the broad utility of the PSD technique including lower analytical cost while also providing a seamless, no additional preparation, extract that can bridge relevant environmental exposure to biological response assays. A brief comparisons with other types of PSD technologies will be presented, including an analytical comparison with SPMDs were we demonstrate an 80% reduction in solvent use, elimination of chlorinated solvents, without a reduction in effectiveness or analytical sensitivity as an example. Finally, results from bridging relevant environmental exposures with two model biological systems, the embryonic zebrafish and Ames models, as a seamless and integrated bio-analytical tool will be presented. Temporal increases of PAHs during active remediation will be discussed. In the second application, PSDs were deployed in water and air at near shore locations in the Gulf of Mexico prior to and during shoreline oiling from the Deepwater Horizon oil spill. Detection limits for individual polycyclic aromatic hydrocarbons ranged from 0.001 to 0.05 ng/L and are typical of the technology. Deployments typically ranged from four to 30 days although other deployment times may be employed. Furthermore, PSD extracts are compatible with both LC and GC screening methods such as the DRS 1,200 chemicals GCMS method. The application of PSD as a surrogate for biota will be presented.