Introduction
Brandon L. Adler and Vincent A. DeLeo Sunscreens and Photoprotection 132
Chapter Contents
Photoprotection Strategies and Sunscreen Recommendations . 2352
Key features
Modern sunscreens were first developed during the 1940s with the primary aim of preventing sunburn. Today, sunscreens are also used to prevent other aspects of photodamage, including carcinogenesis and photoaging
The active ingredients in sunscreens include: (1) soluble organic filters, i.e. “chemical” compounds, that absorb UV radiation; and (2) insoluble metal oxide filters, i.e. “physical” agents, that both absorb and scatter UV radiation
The ability of sunscreens to prevent actinic keratoses and cutaneous squamous cell carcinoma has been demonstrated in human studies, and there is growing evidence that they can also prevent photoaging and cutaneous melanoma
Following topical application, common organic filters are absorbed systemically at levels that exceed the FDA threshold requiring additional safety studies; however, to date there has been no evidence of harm related to their use
Established side effects from sunscreens include irritation (which is common) and allergy (which is rare)
In the laboratory, exposure to oxybenzone was found to be associated with coral bleaching; as a result, some localities have passed legislation prohibiting the sale of oxybenzone-containing sunscreens
Photoprotection and sun avoidance may lead to a decrease in vitamin D levels in some individuals; optimum vitamin D levels can be achieved with a balanced diet and oral supplementation