Scientists have bad news for holiday-makers: the sunscreen protecting your skin as you swim or snorkel in the balmy tropical water might be killing the very coral reef and its amazing marine life that you came to enjoy.
Many sunscreens contain oxybenzone, a chemical that helps filter out the ultraviolet rays that cause skin cancer. Unfortunately, research indicates that it also makes corals more susceptible to the bleaching events that have damaged famed reefs around the world.
It is an example of how synthetic chemicals can have unintended consequences, strengthening the case for more rigorous risk assessment before they are used in industry. Many new substances, including oxybenzone, pass through wastewater plants unfiltered and end up in our rivers and oceans.
Some countries have already taken action to protect vital tourist industries.
“This is a case for the precautionary principle,” says Gabriel Grimsditch, an expert in marine ecosystems at UN Environment in Nairobi. “Oxybenzone shields us from harm. But it is also a pollutant, and we need to know as much as possible about it before letting it loose in the environment. There is already evidence that this substance is harmful to coral reefs.”
Oxybenzone is part of a family of chemicals that are often added to plastics to prevent them from photo-degrading, and to drinks bottles to protect the contents. They also preserve the colours and scents of hundreds of products including hairsprays, soaps and nail polish.
Even without the link to coral decline, many countries have restricted the use of oxybenzone because of concerns that it could harm people’s health, for instance by triggering skin allergies. Researchers are also scrutinizing its impact on hormone levels.
Recent alarm about its impact on marine life stems from a 2015 research paper which said that up to 14,000 tons of sun lotion is washing from the skin of swimmers and divers around the world’s coral reefs every year.
In laboratory experiments, the authors found that oxybenzone reduced the larval form of the coral Stylophora pistillata to a “deformed sessile condition” and was toxic to another five coral species. The chemical “threatens the resiliency of coral reefs to climate change,” they warned.
Several cosmetics firms are already offering “reef-friendly” products that use zinc or titanium oxide instead of the more controversial ingredients.
Other research indicates that it can also harm fish, sea urchins and mammals.
Some countries have already taken action to protect vital tourist industries. Mexico allows only “biodegradable” sunscreen in some of its premier marine parks. Lawmakers in Europe and Hawaii have pushed for more sweeping bans. In the United States, the National Parks Service encourages visitors to use alternative products or just to cover up with hats and long-sleeved swimwear.
Businesses are resisting, pointing out that other factors, including climate change and the discharge of nutrients and other pollutants from the land into the ocean are heavily implicated in the decline of coral ecosystems.
“There is no scientific evidence that under naturally occurring conditions, sunscreen ingredients, which have been safely used around the world for decades, are contributing to this issue,” according to the Consumer Healthcare Products Association, which represents over-the-counter medicine companies in the United States.
However, several cosmetics firms are already offering “reef-friendly” products that use zinc or titanium oxide instead of the more controversial ingredients. Major media outlets such as The New York Times and fashion magazine Vogue have helped to promote them.
So, the next time you hit the beach, you don’t have to wait for the scientific argument to be won or lost. You can exercise the precautionary principle by yourself, reducing the risk to the environment without exposing yourself to the excesses of the sun.