Silicone wristbands are passive sampling devices (PSD) that sequester bioavailable organic chemicals in the environment. In environmental health studies, silicone wristbands are easy to wear and can provide personal exposure data about complex chemical mixtures. This dissertation includes an overview of PSD technology, a literature review of current wristband research publications, and two original studies using new silicone PSD configurations to assess personal chemical exposures. For the first configuration, we designed the silicone pet tag for use on companion animals and demonstrated its use in a case-control study investigating feline hyperthyroidism. We determined that concentrations of the flame retardant tris(1,3-dichloro-2-isopropyl) phosphate (TDCIPP) were higher among pet tags worn by hyperthyroid compared to non-hyperthyroid cats, and we correlated TDCIPP pet tag concentrations with thyroid hormone levels in healthy cats. These results provided converging lines of evidence implicating TDCIPP flame retardant exposures as a risk factor for feline hyperthyroidism. For the second configuration, we developed the military-style silicone dog tag to wear around the neck and investigated occupational and non-occupational firefighter exposures to polycyclic aromatic hydrocarbons (PAHs), phthalates, and industrial-related chemicals. Of the 44 PAHs detected, this study was the first to identify personal firefighter exposures to 18 unique PAHs. We further determined that the dog tag concentrations were higher for the on- compared to off-duty samples and at the high compared to the low call volume fire department. PAH concentrations were strongly correlated with the number of fire attacks a firefighter participated in during the sampling period, compared to firefighter rank and years in the fire service. This suggested that quantitative data, rather than job descriptions and other surrogate data, should be employed for future firefighter chemical exposure assessments. This dissertation demonstrated that silicone wristbands and silicone PSDs can be applied to epidemiological studies to investigate the links between chemical exposures and adverse health outcomes.