Sunscreens are widely used to protect against damaging effects of sun exposure. Avoiding the pain of sunburn is a key motivator for applying sunscreen, however, these products offer much broader protection because when applied correctly and balanced with informed and managed exposure, they can also protect against skin cancer and minimize skin ageing effects. A product category that has such widespread use needs to be very safe in all foreseeable ways. It also needs to be compatible with the environment, in particular marine flora and fauna as it will often be used in coastal areas such as the beach. Due to the general popularity of sunscreens, concerns of any kind tend to spread rapidly, even if an adversity claim has only been formulated as a potential hazard without proper investigation or evaluation of the likelihood and impact of the risk. Even for scientists, risk evaluations are labor-intensive processes that require a solid scientific education, so unsurprisingly, consumers who cannot make such evaluations on their own, often adopt an avoidance strategy towards potential hazards. In the case of sunscreens though, this increases the risk further, and not just in terms of sunburn, because the skin cancer incidence rate also increases. In view of this, it is of utmost importance to stick to the facts, to perform a risk analysis on hazard claims, and to provide clear information to consumers before they consider avoidance actions which may entail not so obvious downsides.
Another concern that has materialized around sunscreen centers on the fact that some UV filters – or combinations of UV filters – are not photostable and degrade, leading to a loss of performance. It sounds like a contradiction in terms that sun radiation itself could reduce the efficacy of a product designed to protect against such radiation. We have therefore revisited this topic and investigated state of the art formulas to assess how much performance is lost after a full day at the beach or on a sunny winter’s day skiing outdoors. We have also looked at the impact of photostability and claim making. What strategy should be followed – especially when creating high protection formulas? Finally, we have considered what photo-stability could mean in terms of the environment.