Sunscreen Tide?

People are encouraged (by dermatologists and manufacturers) to liberally apply sunscreen, especially when they visit beaches. This is to protect their skins from UV radiation (and potential skin cancer). The data seems somewhat confusing but some people are now concerned about the possible effects of sunscreen on marine life (https://www.theguardian.com/environment/2021/aug/06/lotion-in-the-ocean-is-your-sunscreen-killing-the-sea). There is debate about how much sunscreen gets into the seas. One authority estimates that 20,000 tonnes washes off people in the North Mediterranean alone. Another puts the lotion deposited on sensitive coral reefs (by scuba diving etc) between 6 and 14,000 tonnes. Particular concern has focused on UV filters such as oxybenzene, octinoxate and zinc oxide. Some studies have suggested that very low concentrations of some filters and preservatives cause coral bleaching. Some locations (e.g. Hawaii) have banned sunscreens with particular ingredients. Recent evidence suggests, however, that even sunscreens marketed as 'reef friendly', are not without their own damaging effects. Some sunscreens also contain perfluoroalkyl and polyfluroralkyl chemicals (PFAS). PFASs are the 'forever chemicals' that don't break down. They have been linked to a number of human medical conditions. Some people dismiss the environmental impact of sunscreen on coral reefs as 'neglible', certainly compared with global heating (also partly generated by tourists). Others, however, point out that visitors to reefs can be careful about which preparations they use. Tourists only need to apply sunscreen to parts of the skin unprotected in other ways (e.g. by clothing, shade etc).