I just spent the weekend frolicking on the beach, slathered in sunscreen. By protecting myself from the elements, am I doing any harm to the elements? What effect does my Coppertone have on the planet?
Most of us are aware by now that our medicines, soaps, and cosmetics wind up in the environment, where they have the potential to wreak havoc on plants and wildlife. While sunscreen hasn't generated as much concern as, say, birth control, scientists have begun to look more closely at the issue in the past few years. However, there's still a lot we don't know.
To figure out how a particular sunscreen might affect the environment, you have to look at its active ingredients. This is more complicated than you might think: Most UV-protection creams sold in the United States will contain some combination of 17 FDA-approved active ingredients. Two of these are minerals—zinc oxide and titanium dioxide—and the rest are carbon-based chemicals, like octinoxate, oxybenzone, and octisalate, each of which might go by a number of different names.
Both classes of ingredients bring their own health worries. Concerns over the minerals focus on the increasing presence of new, nano-formulations of zinc oxide and titanium dioxide. Though studies suggest that these tiny particles are actually better at blocking UV rays than their larger counterparts, and a number of studies have shown that they don't penetrate healthy skin, many skeptics worry that there just hasn't been enough research done to substantiate safety claims. Certain chemical ingredients, on the other hand, may penetrate the skin and act as endocrine disrupters, affecting users' hormones and reproductive functions.
Though human health and planetary health aren't exactly the same thing, they are related issues: Any mineral or chemical that might be harmful to humans could also damage wildlife and destabilize ecosystems. Though the studies aren't exhaustive, researchers have found detectable levels of chemical UV filters in lakes, oceans, and rivers around the world, with the highest concentrations found near wastewater treatment plants. (Tracing mineral compounds back to sunscreens is more difficult, since it's hard to tell which are naturally occurring and which were synthetically produced; even nano-sized particles may have become so through natural erosion.)
The accumulation of both kinds of UV filters in the water is troubling to some toxicologists because of their potential to build up inside the cells of fish and other marine life. A series of studies conducted in Switzerland found two commonly used chemicals inside fish living in rivers and lakes, though the reports didn't indicate that animals' overall health was suffering.
One of the chemicals analyzed in the Swiss studies was 4-Methylbenzylidene camphor, or 4-MBC, which has been the focus of much international attention due to its potential as an endocrine disrupter—it's been shown to affect birth weight and survival rate in rat studies—but 4-MBC isn't approved as an active ingredient in the United States. However, the Environmental Working Group has found the potential hazard listed in three sunscreens as an "inactive" ingredient (and also in a handful of men's deodorants).
Fewer data are available on the major UV filters used in the United States. Researchers from the University of Riverside did test the effects of one common ingredient, oxybenzone, on a pair of fish species. They found it diminished reproductive abilities but only at concentrations much higher than those observed in suspected areas of contamination in California and New York.
Similarly, according to an Italian study that received a lot of attention last year, a few widely used sunscreen ingredients—oxybenzone, octinoxate, and the common preservative butylparaben—triggered viral infections in the algae that nourish coral reefs, causing the corals to "bleach" and die. Some critics have pointed out that the coral samples in the study were kept in incubators; in real life, the sunscreen would presumably be diluted as the water circulated.
In the wake of these studies—and, it seems, out of a general sense that minerals are more "natural" than chemicals—many green-minded folks suggest switching from chemical sunscreens to the zinc or titanium varieties. But these haven't been proven 100 percent safe for our ecosystems, either. Indeed—in lab conditions, at least—they've been shown to be toxic to zebrafish and potentially harmful to rainbow trout. Some kinds of titanium dioxide nano-particles may also have harmful effects on algae.
There's also the production of sunscreen to worry about. The mining and processing of minerals is both resource-intensive and environmentally taxing. Creating titanium dioxide can result in large amounts of iron sulfate waste or smaller amounts of the more hazardous iron chloride waste. And manufacturing the nano-sized versions may require plenty of extra energy plus more purifying solvent, which generates significant amounts of waste that may be hazardous, depending on the solvent used.
It's hard to tell exactly how the chemicals stack up in terms of production, since manufacturers tend to be pretty closed-lipped about their proprietary formulations. (As an industry, though, metal mining releases more than twice the amount of toxic chemicals as the chemicals industry, according to the EPA [PDF].)
In the absence of better data, then, the Lantern agrees with the researchers who conducted a 2007 literature review on the topic of UV filters and concluded that—while the field deserves further study—"the present state of knowledge is incomplete and insufficient to impose 'environmental protection' measures" on sunscreens.
In the meantime, there are plenty of ways to protect your skin while going a little easier on the Coppertone. Bring a hat or a caftan and find yourself a beach umbrella. If you're feeling brave, you could always try one of those Darth Vader-style sun shades so popular with the ladies of Asia. (The Lantern's mother won't leave home without hers.)
And remember, the stuff that washes off your body isn't the only sunscreen waste you need to worry about. Most dermatologists recommend using a shot-glass-size application each time you lotion up, which means you could end up with another empty plastic tube every few times you go to the beach.
Is there an environmental quandary that's been keeping you up at night? Send it to firstname.lastname@example.org, and check this space every Tuesday.