There are many different potential ingredients in sunscreens. One of the most common is an organic UV filter called oxybezone. Since its wide spread use in sunscreen oxybenzone has been found in water sources and various species of fish worldwide. Oxybenzone has also been shown to contribute to coral reef bleaching. Organic filters such as oxybezone are not easily removed by common waste treatment plant techniques. However there is no evidence that these chemicals in sunscreen are harming humans in the concentrations to which we are exposed. Still, I would recommend when choosing a sunscreen avoid the ones with organic filters such as oxybenzone and favor those with physical blockers such as titanium dioxide or zinc oxide. I addition use sun protective clothing, hats and seek shade. We need to protect ourselves but we dont need to do so at the expense of the environment!
Dermatological and Environmental Toxicological Impact of the Sunscreen Ingredient Oxybenzone/Benzophenone-3
J Cosmet Dermatol 2018 Feb 01;17(1)15-19, JC DiNardo, CA Downs