All sun protection products are resource-intensive and have an environmental impact, which comes from producing the raw materials as well as the product itself, its packaging, and all associated transport. These products also affect the environment after we use them. Aquatic organisms and their ecosystems are particularly affected because most of the products we use eventually end up in the water — when we swim, when we shower after the beach or when we wash clothes and towels with residual sunscreen.
It’s estimated that 25 percent of the sunscreen ingredients we apply end up in the water. A number of scientific publications have attempted to map the effects of various UV filters on the environment. Certain chemicals — including oxybenzone, octinoxate, octocrylene, octisalate, avobenzone, and homosalate — have been identified as particularly dangerous for eco-systems, making coral more susceptible to bleaching, deforming baby coral, and degrading its resilience to climate change.
The United States Virgin Islands recently enacted a ban on the importation, sale, and possession of sunscreen products containing the active ingredients oxybenzone, octinoxate, and octocrylene. Hawaii and Key West, Florida are poised to ban oxybenzone and octinoxate being used in sunscreens. In the rest of the US, however, both filters are permitted (oxybenzone at a maximum level of 6 percent, the same as in the EU).
The more skin-friendly physical filters, titanium dioxide, and zinc oxide have also been shown to adversely affect aquatic organisms such as fish, algae, and crustaceans.
The situation is complex but in order to protect adequately against the sun, my advice will be to use a sunscreen that contains safe chemical filters and physical filters but do not rely on sunscreen alone. Avoid the strongest sun during the day, wear protective clothing, hat, and sunglasses.