Reef Safety Review
Updated: Mar 26
President of ACT Solutions Corp
Zinc Oxide versus Titanium Dioxide and Organic Sunscreens
4,000 to 6,000 tons of sunscreen enters reef areas annually 
90% of snorkelling/diving tourists are concentrated on 10% of the world’s reefs .
Oxybenzone leaches coral of its nutrients and damages DNA, bleaching it of its fluorescent colour. Only 62 parts per trillion of Oxybenzone is needed to inflict this damage .
Organic UV filters can induce the lytic viral cycle in zooxanthellae with latent infections . Zooxanthellae are single-celled dinoflagellates that live in symbiosis with marine invertebrates such as corals, jellyfish, and sea anemones .
Oxybenzone can react with chlorine, producing hazardous reactive by‐products that can concentrate in swimming pools and wastewater treatment plants .
UV filters are not completely removed during waste water treatment and may be carried over into the environment .
Gene expression models of the effects of nanoparticle TiO2 on Caribbean reef‐building coral using Montastraea faveolata have been studied. Though there was significant zooxanthellae expulsion in all the colonies, there was no link to mortality in the star coral .
Nanoparticle ZnO had a higher solubility in seawater than that of larger-sized ZnO and thus potentially more toxic towards algae, but it is relatively less toxic towards crustaceans and fish. The toxicity of nanoparticle ZnO is mainly attributed to dissolved Zn2+ ions .
At high enough concentrations, ZnO encapsulated nanoparticles are shown to be toxic to mussels, but these levels are unlikely to be reached in natural marine water .
Zinc Oxide is the superior choice for formulating a reef-safe sunscreen product.