According to a new study, sunscreen from bathers releases substantial quantities of polluting titanium dioxide (TiO2) into the sea. This has the potential to destroy marine life. This study, which originates from research on beaches in the South of France, was presented at the Goldschmidt geochemistry conference in Boston.
TiO2 is one of the key ingredients of sunscreen, where it serves as a protective against detrimental UV rays: most well-established regulatory bodies consider it safe, in general, for human use at the concentrations used in sunscreens, however, concentrated TiO2 or long-term exposure could be poisonous to a range of fish and other aquatic organisms.
In numerous sunscreens, TiO2 is present as minute nanoparticles, which are coated with protective chemicals. Since the particle size is very small, nano-titanium dioxide does not reflect visible light, but does absorb UV light, enabling a transparent barrier that safeguards the skin from the sun's damaging rays.
The scientists have learned that in water, the nanoparticles are susceptible to losing their protective coating under the impact of UV light or seawater composition, which exposes the more poisonous TiO2 to the aquatic environment.
TiO2 concentrations were measured by them in three beaches near Marseille in France. They also surveyed bathers about how much sunscreen they used, and how frequently they used the water. The team found day-to-day concentrations of 15 to 45 μg/L of TiO2, which corresponds to several kilograms of nanoparticles per summer season per beach.
Lead Researcher, Dr Jérôme Labille (Labex Serenade/Aix-Marseille Université/CNRS, Aix en Provence, France) said: "For example, with one small beach which held around 3000 people daily, we calculate that around 68 kg of cream could be deposited per day, or 2.2 tons over the height of summer. If we consider reasonably that half of the creams used contain 5% of titanium dioxide, this gives 1.7 kg of titanium dioxide released per day: That comes to around 54 kg in the two months of high summer, which is a significant amount. Of course, the sea is more or less continually in motion, so some of the titanium dioxide pollution will be dispersed. Nevertheless, we anticipate an accumulation of titanium dioxide in the seashore littoral, which could affect the wildlife there. In recreation areas with stagnant water, such as in lakes or seawater swimming pools, then there will be no such dispersion and the accumulation would be expected to be even more pronounced.
It is important to keep this in perspective; titanium dioxide is a pollutant, and we need to take measures to try to reduce the quantities of TiO2 which are concentrated in the aquatic environment, where it can be harmful to fish and other organisms. Nevertheless, it is extremely important that sunbathers continue to use sunscreen for skin protection, the titanium dioxide pollution needs to be dealt with by the manufacturers and possibly legislation, and we've had good feedback from the manufacturers we are working with".
The scientists take into consideration that in early July of this year, Hawaii banned some sunscreens which were discovered to be endangering coral reefs (this was not because of TiO2).
The good news is that we are working on nanoparticle UV filters and sunscreen formulations which will reduce the potential damage from titanium dioxide. We're looking at developing sunscreens which are "safe by design" in which the release and toxicity of nanoparticles will be minimized, so we anticipate that a solution to this problem isn't too far away.
Dr Jérôme Labille, Lead Researcher
This work is of special interest, since it shows for the first time how nanoparticles from cosmetics may influence the aquatic environment. Earlier work from our group has shown this for lakes and rivers, but this is the first study for the marine environment.
Dr. Thilo Hofmann from the University of Vienna
This is an autonomous comment; Dr Hofmann was not involved in this study. Dr Hofmann Chaired the session in which this study was presented.
This research was sponsored by Labex Serenade and OHM Littoral Méditerranéen.