If you're going to slather on sunscreen before jumping in the water, you might want to check the label first.
The state of Hawaii is moving forward with a groundbreaking plan to ban the sale of all sunscreens containing the chemicals oxybenzone and octinoxate by the beginning of 2021.
The Hawaii senate just sent the bill to governor David Ige, who's expected to sign it into law in the coming days.
The state says these chemical sunblocks can kill developing coral; induce feminization in adult male fish; and mess with normal development in fish, sea urchins, coral, and shrimp.
If concentrations are high enough, they can damage a coral's DNA, potentially making its life shorter and sicker.
Studies suggest that the chemicals promote coral bleaching at lower-than-normal temperatures, and they may also be hormone disruptors, increasing reproductive diseases.
"Some sunscreen chemicals, in certain situations, cause coral larvae to stop swimming, change shape, and ultimately die," a 2018 briefing from the International Coral Reef Initiative (ICRI) explains.
"Oxybenzone has been shown to be an endocrine disruptor, causing the outer epidermal cells of coral larvae to turn into skeleton at the wrong stage in their development."
Many of the previous studies on corals have been done in the lab, and the chemicals are usually present in tiny concentrations once they get mixed into the ocean.
Concentrations of oxybenzone greater than one part per million were found in one study in the US Virgin Islands, but concentrations in areas studied around Hawaii were lower.
The ICRI says more research in the wild is needed to know for sure whether the amount of sunscreen that's present in ocean waters really has a measurable effect on coral health.
What kind of sunscreen you can use
There are two broad classes of sunscreens. Chemical sunscreens – those are the ones Hawaii is worried about-use chemicals to block harmful UV rays.
Oxybenzone, for example, works by absorbing a particular wavelength of UV and converting it into heat energy, keeping you from getting burnt.
The other class of sunscreens uses minerals to physically put a barrier between your skin and the sun. These are called mineral blockers, and while they block out the sun by bouncing light off your skin, they can also make your skin really white.
They often include ingredients like zinc, aluminium, and titanium (think: lifeguard nose).
"They're like tiny metal particles that you're putting on the skin," dermatologist Kathleen Suozzi from the Yale School of Medicine recently told Business Insider.
Mineral blockers also provide better protection, and are less likely to cause skin reactions, she said.
"I typically recommend those [mineral blockers] to my patients because they have much less risk of being irritating to the skin, and you're getting that broad-spectrum coverage."
Many mineral blockers have become easier to use in recent years. As manufacturers start adding in tints and micronizing particles, the products have become more sheer and less white than ever.
Not all of these improvements are good for the corals. Researchers say the nanoparticle form of zinc oxide may not be safe for marine life.
The UK-based NGO MarineSafe has started stamping its seal of approval on products it deems safe for ocean life, and keeps a list of dangerous chemicals online.
Sunscreen is far from the biggest problem the world's corals are facing. Many experts believe the invertebrates could be completely wiped out in just decades, as our oceans heat up and become more acidic.
Still, if it turns out we can help coral better reproduce by dumping fewer chemicals into the water when we swim, it's probably worth a try to save the rocky, colourful, quiet corals that are hard at work protecting coastlines all over the world.
This article was originally published by Business Insider.
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