PROJECT SUMMARY / ABSTRACT Problem to be Solved and Significance: Exposure to Ultraviolet radiation (UVR) is a risk factor for the development of skin cancer, and health care agencies recommend that sunscreens be used as a preventative measure. Recent legislation in the U.S. and internationally has banned the sale of ingredients that are fundamental to water-resistant sunscreens, creating an urgent need for new products that satisfy existing and emerging legislation. Product and Long-Term Goal: The product of this SBIR will be a wholly biocompatible SPF 30 broad spectrum sunscreen cream, sold in 6-oz tubes, that satisfies FDA?s criteria to be labeled as ?Water Resistant (80 min)? and is based on the Nanometics (d.b.a. PHD Biosciences [PHD]) proprietary elastomer technology. Successful development of this sunscreen product directly addresses the mission of the National Cancer Institute by improving protection against UVR and decreasing the risk of skin cancer. Technological Innovation: The PHD sunscreen incorporates PHD?s proprietary biodegradable elastomer technology, which is the first plant derived elastomer for topical products that provides water resistance, is compatible with all Food and Drug Administration approved UV filters, and recapitulates the favorable aesthetic properties of silicone elastomers. Specific Aim #1. To demonstrate that the PHD Sunscreen is water resistant for at least 80 min on healthy volunteers. Studies in this Aim will be conducted under FDA guidance and will demonstrate the feasibility that the PHD sunscreen is resistant to removal with water after 80 min of continuous immersion in water. Success Criterion: This Aim will be successful if after 80 min of water immersion, the mean SPF falls within one standard deviation of the pre-immersion SPF of 30. Commercial Opportunity: The global sunscreen market is projected to exceed $2.5 billion by 2023. Primary and secondary market research supports the need for the PHD Sunscreen to meet the emerging needs created by new legislation. Phase II SBIR studies will include additional studies to confirm safety on a larger number of volunteers; compare performance to leading commercial sunscreens; and optimize the chemistry, manufacturing, and control (CMC) processes to produce the product at commercial scale.