This pilot study is intended to evaluate the dose-response associations between measured UV exposure and individual serum 25 (OH)-vitamin D levels. To date, there is little data and a great deal of mis-information about vitamin D. Caucasians have a variety of skin types and melanin production. This pilot study is unfunded and we know that there is extreme heterogeneity among Caucasians in their absorption of UVB and subsequent synthesis of vitamin D. Among our volunteers 2 participants with Hispanic ethnicity are represented as well. Darker-skinned individuals, such as African Americans, produce considerably less vitamin D, based on the bone health literature. Inclusion of African Americans will be critical in the future as we develop our understanding of the relationship between vitamin D and UV exposure. Our collaborator, Elizabeth Jacobs at the University of Arizona, is currently conducting a pilot study to evaluate UV and serum vitamin D among individuals with darker pigmentation. The motivation for our pilot study has to do with the balance between vitamin D and sun exposure as a risk-benefit assessment for the development of melanoma. Asians and African Americans do develop melanoma, but at a rate ten times less than Caucasians and it does not appear to be related to sun exposure; thus, to include them at this time would not allow us to focus on the medically-related issue.