Silicones are ubiquitous in personal care products with good reason. The variety of silicone materials available and their unique performance characteristics make them beneficial for a wide range of cosmetic applications. Decades of scientific research, combined with actual experience in market applications, have provided a large knowledge base relevant to safety and environmental aspects of silicones. The materials science of silicones is also well-developed and has enabled an understanding of the relationship between fundamental physical/chemical properties and bulk material properties. This article attempts to summarize important aspects of these relationships, specifically with respect to safety and environmental considerations associated with personal care products. Linking key performance characteristics at a macro level with underlying chemistry on a molecular scale can provide a deeper and broader foundation for design, formulation and development of personal care products. With structure-property relationships established, a brief summary of current literature relating to environmental aspects of the use of silicones is provided. This should assist in evaluating various claims made in connection with personal care products containing silicones.