Palau is an example of this, because the substances released by the creams whiten the corals.

To be effective, sun creams must contain sun filters , i.e. substances that protect us from ultraviolet UVA and UVB rays. However, no product is capable of filtering 100% of UVA rays.

Sunscreens can be of 2 types, physical and chemical:

• chemical filters absorb solar radiation and transform it into heat (banned in eco and organic products)
• physical filters reflect it

They are synthetic molecules created in the laboratory which are quite polluting for the environment. But not only that: if they are not resistant to solar radiation while absorbing the energy of UV rays, they could cause skin problems.

For example molecules such as Oxybenzone=benzophenone-3, 4-Methylbenzylidencamphor, Paraaminobenzoic acid(PABA) are considered problematic.

Warning: these elements are often present in cosmetics too!

Chemical filters are prohibited. In eco-bio sunscreens we will only find physical filters , therefore titanium dioxide for UVB (Titanium Dioxide) combined with a filter for UVA rays, often gamma oryzanol or zinc oxide.

Warning : to improve the pleasantness and spreadability of the cream, titanium dioxide is often reduced into Nano particles (very small) to avoid the very evident white layer on the skin, but at the same time this reduction into small particles can cause the formation of free radicals . This is why if titanium dioxide is present an antioxidant is needed in the cream to stop oxidative phenomena

Without prejudice to having to use bio.eco creams for our health, without Nano molecules, let's think about the environmental impact
Lately it is easy to find, if we want, eco-friendly sun creams (therefore based only on physical filters) containing Pongamia Oil, to shield UVA rays, clearly reducing the impact on the water (shower/sea/swimming pool).

Non-bio.eco creams contain petrolatum and other substances that are very harmful to the marine ecosystem in which we immerse ourselves. They cause numerous damages to the waters and to the health of its inhabitants, so much so that in some places in the world they have even been banned to avoid damaging the coral reef or other particular habitats.

Yes, really, because physical filters do not degrade over time (while non-bio-eco creams with chemical filters degrade over time).

I recommend you consult this precious link from Zago Ecobiodizionario .