Sunscreens are made from a variety of different chemicals to prevent UV rays from damaging your skin. While the main aim of a successful sunscreen is to protect you, many chemicals in sunscreen have been found to harm organisms in the ocean, such as coral reefs.
A study published by Science examined the effects of oxybenzone on corals and sea anemones and found that they both absorb the chemical. The cells of these organisms then transform oxybenzone into phototoxins, which become toxic when exposed to sunlight. Experiments have shown that at a minimum, 0.14 mg of oxybenzone per litre of seawater is fatal to half a coral larvae population within 24 hours. This raises concern as samples collected in the U.S. Virgin Islands showed oxybenzone concentrations of up to 1.4 mg/L of seawater.
“While more research needs to be done looking at the effects on humans we know this chemical harms coral reefs which are integral organisms in the ocean. If a decrease in population is seen this could lead to a loss in habitat and food source for thousands of species,” said Jessica Hu, a 4A Environmental Science student
Hawaii has since issued laws to protect coral reefs by banning oxybenzone in 2018, with the Virgin Islands, Palau, and Aruba following suit with their own restrictions.
The study also ran an experiment to determine how oxybenzone was affecting coral reefs by analyzing anemones, a closely related organism. The experiment used 2 mg of oxybenzone per litre of seawater and observed how the chemical reacted when the anemones were kept in the dark versus being exposed to light. The study found that after 17 days all the anemones kept in the light had died while the ones kept in the dark survived, thus confirming that oxybenzone acted as a phytotoxin. Further studies found that absorption by the anemones caused the conversion of the chemical into phototoxins.
Currently, there is research being done exploring the potential of oxybenzone becoming phototoxic in human cells. It was found that human cells can potentially create phototoxins from oxybenzone, which could be particularly dangerous if this process occurs in the skin, thus being exposed to light.