We all want to make choices that are gentler to Mother Earth. She’s our home, after all. This is on our minds right now because Earth Day is April 22!
For a while now, physical or mineral SPF has been touted as the “green” choice compared to chemical SPF. But sometimes there’s more to a story than the headlines. Today we’re examining if mineral SPF really is the best choice from an environmental perspective, and what the evidence means for you.
First, let’s define the difference between mineral and chemical SPF. Mineral or physical SPF contains ingredients like zinc oxide that block harmful radiation from the sun. Chemical SPF contains ingredients like oxybenzone that absorb the harmful radiation and convert it into heat before releasing it. Both types of SPF, when applied correctly, effectively prevent photoaging, sunburns, and skin cancer due to sun exposure.
For many years, we’ve heard claims that chemical SPF is bleaching coral reefs. But what evidence is there to support that claim? And is mineral SPF really better for the environment in comparison?
Examining The Body Of Evidence
There are just two scientific studies that led to the belief that chemical sunscreen causes coral bleaching. The first study placed small fragments of coral in plastic bags with very high concentrations of chemical SPF ingredients for a few days. The corals were bleached at the end of the study, and from this observation, the scientists concluded that up to 10% of world reefs are potentially threatened by sunscreen-induced coral bleaching. While they showed that large concentrations of chemical sunscreens can bleach coral, it’s a pretty big logistical leap to assume that 10% of the world’s reefs are exposed to that much sunscreen.
The second study used one-day-old coral larvae and exposed them to different concentrations of sunscreen chemicals in artificial ocean water. At higher concentrations of chemicals, the larvae bleached. They also took samples of ocean water at seven different locations in Hawaii. But the researchers only did one sample per location, which is not that many. Think about it: maybe sunscreen chemicals are more concentrated at certain times of year, or on certain days, like Saturdays, when more people are out swimming. Repeating the samples would have given the scientists higher quality information. Nevertheless, only one of the seven samples had measurable levels of sunscreen chemicals.
Additionally, both studies used higher concentrations of these chemicals in their lab testing than scientists have observed in samples of actual ocean water. A recent review of the amount of benzophenone-3 in reef waters found that sunscreen chemicals are not very concentrated in ocean water–usually, a few parts per trillion. That’s barely detectable. So while coral bleaching is a big problem, the body of scientific evidence does not support the claim that chemical SPF is a major cause of coral bleaching.
So, it could cause damage at high enough concentrations. But we don’t have a sufficient body of evidence that it currently is causing this damage. It’s still an area of active research. We don’t have as clear an answer as the headlines might make you think.
What are the environmental impacts of zinc oxide?
Zinc oxide is the active ingredient in many mineral SPFs. And it has environmental impacts, too. First, zinc oxide mining and processing takes a lot of energy. It has to be mined from the earth and is in a combined state with other elements when it comes out of the ground. So zinc has to be extracted from the ore and purified, a process that requires temperatures as high as 950 degrees Fahrenheit. It takes a lot of energy–and therefore carbon emissions–to produce zinc oxide.
Second, zinc mining can cause contamination. In 2019, the Canadian government concluded that zinc compounds could harm the environment at then-current levels of concentration, particularly in water waste from the mining process. Officials were concerned that zinc in the water supply could damage aquatic ecosystems.
So basically, both types of SPF ingredients–mineral and chemical–have potential environmental drawbacks.
What does it all mean?
It’s hard to pick a clear winner from an environmental perspective. So does that mean we shouldn’t use SPF? Of course not! One in five Americans get diagnosed with some kind of skin cancer in their lifetime–that’s a big public health problem. SPF can prevent these cancers and save lives. We say, pick the type of SPF you like and use it every day. The best SPF is the one you use. Some people have a strong preference one way or another, and other people can use both kinds.
The good news is, if you’re concerned about the environmental impact of your beauty routine, there are ways to help! You can take steps like:
- recycling your product packaging
- swapping in plastic-free packaging
- using products with minimal packaging–think shampoo bars and toothpaste lozenges
- using refillable packaging (like lipsticks with refillable cartridges)
Reducing plastic waste is one of the most effective things you can do right now to protect the ocean and the planet.
Hopefully this blog helped you sort through the attention-grabbing headlines on SPF and coral bleaching. If scientists reach a consensus on this issue we’ll be sure to give you an update! Remember, together we can take small steps every day to show the Earth more love.