When should sunscreen be applied: The balance between health benefit and adverse consequences to humans and the environment

Abstract

Objective: To propose a strategy for using sunscreens that optimizes the balance between skin health and adverse effects to humans and the environment. Methods: A model was developed to explore the relationship between sunscreen usage and personal sun exposure throughout the year in populations resident at different latitudes. Results: There is little biological justification in terms of skin health for applying sunscreen over the 4–6 winter months at latitudes of 45° N and higher, whereas year-round sunscreen is advised at latitudes of 30° N and lower. Avoiding sunscreen application at times when it is biologically unnecessary results in an annual reduction in sunscreen use of 25%. Furthermore, using products containing UV filters over the winter months at more northerly latitudes could lead to a higher number of people with vitamin D deficiency. The single largest use of sunscreen is on a sun-seeking holiday and encouragement to make more use of clothing and shade would appreciably reduce the sunscreen burden to the environment. Conclusion: We need to use sunscreens wisely so that we gain the health benefit from their use while at the same time limiting possible harm to ourselves and the environment.