Cottage Q&A: Environmentally-friendly sunscreen

I’m concerned about the amount of sunscreen that must get washed off in the lake each day. Are there any sunscreens that are environmentally friendly?—Mary Mansworth, Charleston Lake, Ont. 

If by “environmentally friendly” you mean “less harmful” then yes. Science time! Sunscreens are usually categorized as either chemical (“organic”) or physical/mineral (“inorganic”). Both protect your skin from UV rays, they just work differently. So far, most research has focussed on the effects of chemical sunscreen’s common UV-filtering ingredients on marine environments, in particular, on coral reefs. But lately, there’s been a small-but-growing amount of research on freshwater ecosystems. A recent study out of the University of Alberta looked at the effect of chemical UV filters on water fleas (tiny crustaceans common in North American lakes). The findings were not good given how important these fleas are for a lake’s food chain. Forty-eight hours of exposure to UV filters had a harmful effect. Fourteen days proved deadly.

You’re not going to find a skincare product that’s friendly to the lake. And swimming covered up head-to-toe, wearing a wide-brimmed hat, probably isn’t realistic. But since physical sunscreens don’t contain oxybenzone, avobenzone, or other chemical UV filters, this makes them a potentially less-harmful option. Check labels when you shop: “I would recommend inorganic chemical compound sunscreens that contain mostly titanium dioxide or zinc oxide,” says Sunil Kalia, an associate professor at the University of B.C., a certified dermatologist, and the chair of the Canadian Dermatology Association’s Sun Awareness Working Group committee. 

Buying, using, and storing sunscreen

Don’t chuck your current product just yet. There’s a reason why physical sunscreens aren’t wildly popular. They’re thick and tend to leave behind white marks. Also, remember that the impact of any pollutant is going to depend on the amount getting into the water, and the volume of the lake. 

Is yours packed like a Florida beach during Spring Break? “If you have a lot of people in one area—that’s when you’ll see a big spike in concentration,” says Aaron Boyd, the graduate student who led the University of Alberta study. “And with UV filters, the effects tend to be local: a high concentration in the vicinity, that rapidly decreases as you move away. In my opinion, organic UV filters are not necessarily going to be the most toxic chemicals in your average body of water.” 

Scientists one step closer to inventing sunscreen pill

We’ve said it in this magazine before: the best sunscreen is the one that you’re going to wear. You don’t want to put your own health at risk here. “Skin cancer is much worse than anything that’s happening to the environment,” says Boyd.

This article was originally published in the June/July 2021 issue of Cottage Life magazine.

Got a question for Cottage Q&A? Send it to answers@cottagelife.com.

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