The Darker Side of Sunblock

This time of year, sunblock is part of the daily routine for many Americans. Wake up, slather it on, and go outside.

For those concerned about the chemicals we put on our bodies, sunblock represents a double-edged sword. On one hand: what kind of chemicals am I putting on my skin and spreading into the environment? On the other hand: I don’t want skin cancer. Or, more immediately, a sunburn.

For a parent with small children, sunblock is even more crucial. It’s difficult to explain the dangers of staying out in the sun too long to your four-year-old. An adult might do something sensible like sit in the shade or wear a hat.

When you’re packing your kid off to spend a day at the beach with her friends, all bets are off. And nothing feels worse than watching your kid suffer from red, burning, peeling skin and knowing it’s your fault.

But many sunscreens now pack unseen hazards: nanoparticles.

Specifically, I’m talking about nano-titanium dioxide and nano-zinc oxide. These are particles that are measured in nanometers — one billionth of a meter. That’s a measurement many times smaller than the width of a human hair. Sunblock manufacturers like them because they help the sunscreen go on without that undesirable “I just smeared cream cheese all over my face” look.

Manufacturers often don’t disclose the presence of nanoparticles in their products. The ingredient list might just say “titanium dioxide” or “zinc oxide,” omitting the “nano.” But you’ll find these tiny particles in brands like Coppertone, Banana Boat, Neutrogena, Aveeno, and even Burt’s Bees “Chemical-Free” Sunscreen.

Sometimes, these products even sport “non-nano” labels, which take advantage of wiggle-room in definitions to mislead consumers.

Nanotechnology is so new that it’s not yet well-regulated or even well-understood. Scientists are developing commercial uses for it faster than they’re assessing its safety. However, some of the early research is troubling.

To put it simply, size matters. A chemical that might be safe in its normal-sized form might not be when it goes nano. As the group As You Sow writes in its issue brief on nanotechnology in food, “Because of their small size, nanoparticles are able to go places in the body that larger particles cannot.”

One study suggested that particles might penetrate skin cells, causing DNA damage after exposure to sunlight. The fear is that this could lead to cancer — exactly what sunblock is intended to prevent.

If you want to avoid nanoparticles until scientists have assessed safety concerns and regulators have banished dangerous products from the market, here are a few guidelines to follow.

First, zinc oxide particles in sunscreen tend to be larger than titanium dioxide products that appear clear on the skin. They also provide better sun protection.

Second, if a product contains titanium dioxide and it goes on your skin without a whitish tint, it’s nano.

Third, and probably most important, when you buy sunscreen, avoid the spray-on kind. Yes, they’re convenient — especially for protecting a squirmy 4-year-old’s skin — and can make it easier to keep sunblock off your hands. But while nanoparticles won’t penetrate your skin, they can cause trouble if inhaled. And you’re way more likely to inhale sunblock that’s sprayed instead of slathered.

Consumer Reports says that if you have no choice besides a spray, spray it on your hands and then rub it on your skin, particularly for children and for your face.

Finally, you can skip the chemicals altogether if you simply wear protective clothing like a hat, time your visit to the beach so you aren’t there when the sun is strongest, or sit in the shade while you’re outside.

Consumers can’t solve this quandary on their own and sunscreen manufacturers haven’t done enough to find a solution. What we really need is adequate labeling so that we’ll all know what we’re buying and better regulations that will keep the truly dangerous products off the shelves.