|Abstract or Summary
- Passive sampling is a popular technology for environmental monitoring, and silicone is an ideal choice for a variety of passive sampling applications. The silicone work described here encompasses laboratory and field studies that demonstrate the use of this polymer in novel environments, for new applications, and for emerging compounds. Unique attributes of silicone polymers make them advantageous for targeting semi-polar contaminants not typically targeted in environmental research. Oxygenated polycyclic hydrocarbons (OPAHs) represent an emerging class of contaminants with chemical properties well suited to silicone passive sampling. The first challenge was to create a robust OPAH analytical method to examine these compounds in silicone, and two independent methods (liquid as well as gas chromatography) were optimized and demonstrated for 24 ketone-containing aromatic hydrocarbons, more than other methods published at that time. An isotopically labeled OPAH was used as an internal standard in contrast to previous methods which used only labeled polycyclic aromatic hydrocarbons (PAHs). The efficacy of each method was further demonstrated by comparing standard addition to internal standard quantitation. Next, OPAHs, PAHs and pesticides were used to compare several silicone materials with low density polyethylene (LDPE) at Portland Harbor Superfund field sites. Target analyte detection, precision, and practical considerations in the field and laboratory were used to evaluate
silicone materials. Individual differences between LDPE and the most optimal silicone polymer for OPAHs highlighted the importance of using optimized methods or polymer choice for a particular analyte class. Biggest differences were found for 9-fluorenone, benzanthrone, and 5,12-naphtacenequinone. After this successful polymer comparison, the next study involved a novel application of silicone wristbands as personal passive samplers. Commercially available silicone was modified to serve as personal samplers and tested in both an ambient and occupational settings. Silicone wristbands provided a valuable tool to monitor individual exposures that were time weighted averages of personalized exposure. The ambient study captured 49 individual compounds including PAHs, personal and consumer products, pesticides, phthalates, and as well as other industrial compounds. In the occupational study, roofers working with hot asphalt wore silicone samplers and evidence of both temporal (day versus week deployment, p < 0.05), and spatial (between two roofing sites p < 0.05), sensitivity was found for PAHs, and two OPAHs were detected in some samplers as well (9-fluorenone and benzofluorenone). Finally, another novel application was developed for silicone as an in vivo monitor of persistent organic pollutants. Human silicone breast explants were found to contain chlorinated pesticides, and p,p-DDE and PCB 118 were used in murine models as an in vivo sampler to explore silicone as a biomonitor and sink of organic contaminant exposure. Silicone was found to sequester both compounds in vivo, and partition values from mouse data were used to predict human adipose tissue concentrations that were within literature values. This work presents silicone as a complimentary and useful material in traditional and novel environmental monitoring applications in order to promote a better understanding of exposures, chemical mixtures and environmental contamination.