A review of environmental contamination and potential health impacts on aquatic life from the active chemicals in sunscreen formulations

The active chemicals in sunscreen formulations are released into the environment from human skin, and found in recreational-use waters like seawater, but can also be washed into fresh water from bathing and showering. The level of sunscreen chemicals found in samples varies considerably between regions, time of year (higher in summer months), and time of day. Average typical concentrations are only in the nanograms per litre (ng L^-1) range in marine and fresh water systems, and typically, the highest levels are in waste-water sludge because of a concentrating effect during the treatment process. From numerous studies, it is known that the active chemicals in sunscreens can have potential hormonal/oestrogenic activity and non-hormonal effects, including: acting as teratogens, altering gene regulation, inducing changes in antioxidant and free radical production, and inducing coral bleaching. However, the effects of sunscreens on aquatic life under laboratory conditions typically occur only at concentrations (µg or mg L^-1) that far exceed (10-10 000-fold) levels found in the environment. As such, when damage does occur to reefs and animal life, there are often other causes that are more likely impacting the aquatic life including changes in water temperature, water turbidity, elevated nutrient levels, and the presence of pesticides and medicines used for human and animal health.