Sorry for this late update of thematic report. Today, I want to share with you one of the most commonly used item in summer: sunscreen and discuss how it is severely affecting the marine life in a less-apparent way. 

We may often spot a plastic bag or bottle in the sea, but these chemicals in the sunscreen covered our body could get released into the ocean by swimmers and tourists without notice. In fact, it is estimated that up to 6,000 tons of sunscreen are washed into coral reefs around the globe each year [1]. As it gets deposited in the water, some regions may form an oily iridescent sheen on the surface. And this is not the only way the chemical enters oceans. Oxybenzone, one of the most common UV-blocking chemical, can be absorbed by human skin and detected in urine within 30 minutes of application [2]. Therefore either washing off the sunscreen or excretion can pollute the water and if water is not treated sophisticatedly, the chemicals could lead to tremendous impact by polluting marine life, especially coral reefs. 

Fortunately, not every single coral reef is affected by humans’ sunscreen and personal care product. But the ones that are most seriously affected are most important to humans. For instance, the coral reef region for tourism as well as fringing reefs that are essential to prevent coast erosion [2] as well as marine food that local fishermen relied upon.

Oxybenzone affects coral reefs in many ways. A recent study shows that it can induce coral bleaching, damages coral DNA as well as induces severe and lethal deformities. And these pathologies will occur at concentrations as low as 62 parts per trillion, but the beaches in Hawaii have shown exorbitant concentrations of 700 parts per trillion [2]. Moreover, other studies have shown the oxybenzone concentrations on nearshore reefs globally reached to a level between 200 parts per trillion and 200 parts per billion, which is sufficient to cause significant environmental impact. In July 2028, Hawaii became the first U.S. state to ban the sale of sunscreens containing oxybenzone and octinoxate [1]. 

Image source: https://www.parley.tv/updates/2018/12/17/sunscreen-worse-than-climate-change

You may start to wonder about sunscreen that contains less harmful or completely safe chemicals to marine life. Merchants start to label products that do not contain oxybenzone and octinoxate “reef-safe” sunscreen to attract customers. Yet the truth about reef-safe sunscreen is that though oxybenzone and octinoxate are the most widely studied, many other ingredients of these sunscreens are still harmful to our environment. 

However, we still need sunscreens to prevent sunburns and skin cancer. Rather than abandoning sunscreens, we can adopt more reef-friendly approach to reduce the amount of sunscreen we used. For example, we can cover most of our body with UPF (ultraviolet protection factor) clothing or we can choose to use mineral sunscreens with “non-nanotized” zinc oxide or titanium dioxide [1], or even use use an oxybenzone-free chemical sunscreen.

References:

Calderone, Julia. “The Truth About 'Reef Safe' Sunscreen.” Consumer Reports, 7 Feb. 2019, www.consumerreports.org/sunscreens/the-truth-about-reef-safe-sunscreen/.

Downs, Craig. “Sunscreen Pollution.” MarineSafe, 3 May 2016, www.marinesafe.org/blog/2016/03/18/sunscreen-pollution/.