Sunscreen Protects Skin, but Does It Burn the Planet?

To slather or not to slather? The jury's out.
To slather or not to slather? The jury's out. (Picture Source/picturequest)
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By Nina Shen Rastogi
Thursday, May 28, 2009

How green is sunscreen? 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. Although sunscreen hasn't generated as much concern as, say, birth control drugs, 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 know its active ingredients. That is more complicated than you might think: Most UV-protection creams sold in the United States contain some combination of as many as 17 FDA-approved active ingredients. Two of those, zinc oxide and titanium dioxide, are minerals; the rest are carbon-based chemicals such as 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 better at blocking UV rays than are their larger counterparts, and though a number of studies have shown that they don't penetrate healthy skin, many skeptics say not enough research has been 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.

Human health and planetary health aren't the same thing, but they are related: Any mineral or chemical that might be harmful to humans could damage wildlife and destabilize ecosystems. Though the studies aren't exhaustive, researchers have found chemical UV filters in lakes, oceans and rivers around the world, with the highest concentrations found near wastewater treatment plants. (Tracing mineral compounds to sunscreens is more difficult, because it's hard to tell which are naturally occurring and which were synthetically produced; even nano-size particles could be products of 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 of these commonly used chemicals inside fish living in rivers and lakes, though the reports didn't indicate that the animals' overall health was suffering.

One chemical analyzed in the Swiss studies was 4-methylbenzylidene camphor, or 4-MBC. It has been the focus of much international attention because of its potential as an endocrine disrupter: In studies of rats, it has been shown to affect birth weight and survival rates. 4-MBC isn't approved as an active ingredient in the United States; however, the Environmental Working Group, a nonprofit advocacy organization, has found the chemical in three sunscreens, listed 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 at the University of California at Riverside did test the effects of one common ingredient, oxybenzone, on two fish species. They found that 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 presumably would be diluted as the water circulated.

In the wake of those 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 those haven't been proved 100 percent safe for our ecosystems, either. Indeed -- in lab conditions, at least -- they've been shown to be toxic to zebra fish and potentially harmful to rainbow trout. Some kinds of titanium dioxide nano-particles might have harmful effects on algae.

There's also the production of sunscreen to worry about. The mining and processing of minerals is 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-size 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, because manufacturers tend to be tight-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.)

In the absence of better data, then, the Lantern agrees with researchers who conducted a literature review on the topic of UV filters in 2007 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 at the beach while going a little easier on the Coppertone. Wear 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 sunshades so popular with the women of Asia.

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.

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