Are nano-materials in sunscreens worth the risk?

I’m a swimmer, and in summertime I swim most days in a large natural pool in my hometown. That’s it on top of this post. Isn’t it great? The water flows into the pool from an underground aquifer, and it stays very cold (hovering a few degrees either side of 68 degrees) throughout the year. But what if you sunscreen contains nano-materials?

Because of this beautiful spring-fed pool – which empties into a creek, which feeds into a river and then an ocean – and because I was born and raised in Texas where swimming pools are part of our culture – sunscreens have special significance to me. That’s why it has concerned me for some years that manufacturers are now creating clear sunscreens via the use of nano-particles.

Now Friends of the Earth along up with Consumers Union (publisher of Consumer Reports) and the International Center for Technology Assessment have compiled a report about nanomaterials in sunscreens (pdf), suggesting these products are not worth the risk.

What are nano-particles, and why are they in sunscreens? Nanotechnology is a relatively new technology – a glimmer in the eye of the world’s most brilliant physicists in the 1950s – brought into reality in the 1980s by such innovations as the scanning tunneling microscope. Nanotechnology is about manufacturing. It’s about creating things at the molecular and atomic scale – things so small that they’re measured in nanometers, with each nanometer measuring one-billionth of a meter.

A particle tens of thousands of nanometers in length is still much, much too small for the human eye to see. A conventional microscope can’t detect individual molecules that are a few nanometers in diameter. A slice of a single strand of hair – sliced across like salami – would measure about a hundred thousand nanometers across.

Scientists can now manipulate the world at these minute scales. And it turns out that materials act profoundly differently when they’re at nanoscale. At this scale, a material’s properties change. That’s why nano-particles in sunscreens create a sunscreen that’s clear instead of white.

Nano-particles are not found in nature. They’re manufactured by scientists.

And I’m not saying they’re dangerous. When I told my colleague Jorge Salazar I was writing this post, he scoffed, saying, “Titanium oxide is pretty benign stuff.” Manufactured nanomaterials are being used in sunscreens to make sun-blocking ingredients like titanium dioxide and zinc oxide rub on clear instead of white. I don’t know if these particles are dangerous, but it’s not knowing that scares me.

The Consumers Union tests of nano-sunscreens found no correlation between nanomaterial content and sun protection. Adding nano-particles to your sunscreen is for cosmetic purposes only. No more unsightly white noses around the pool.

I do know that nanomaterials have not been around very long, so they have not been tested as thoroughly as one could wish. How could they be? When I was a kid hanging out at the pool at the local YMCA, nano-particles didn’t exist and some people proudly sported white, sun-screened noses. Some available data show the small size of nano-particles makes them more able to enter lungs, pass through cell membranes, and possibly penetrate damaged or sun-burned skin. Other studies have suggested there may be environmental impacts stemming from the release of nanomaterials into broader ecosystems, like the natural-springs pool where I swim each summer now, or like the creek that pool spills into. According to Friends of the Earth, a 2006 study “demonstrated that some forms of titanium dioxide nanoparticles (popular ingredients in nano-sunscreens) are toxic to algae and water fleas, especially after exposure to UV light. Algae and water fleas are a vital part of marine ecosystems.”

Jorge says don’t worry. He says the biggest risk from nano-particles is to workers who produce nano-containing products. In the U.S. and elsewhere, there are currently no established safe levels of exposure to nanomaterials and no reliable systems and equipment to protect workers from harmful levels of exposure. A recent report from China indicates a link between exposure to nanoparticles and severe illnesses suffered by seven factory workers. One of the workers died.

According to Friends of the Earth: “Consumers need to know that manufactured nanoscale zinc and titanium oxides are not necessarily the most effective or safest choice for effective sun protection. They are also not the only option. Besides several different carbon-based active ingredients, consumers can also look for larger-scale, more opaque metal-oxide based sunscreens (e.g. titanium dioxide or zinc oxide which are ‘inorganic’ and do not contain carbon atoms), although without mandatory labeling these may be very hard to find (at least in the U.S.).”

As for me, a Texan born and raised … swimming pools are important to me. Typically, I go swimming early in the morning before the sun gets too high. So I don’t wear sunscreens, not even on my nose, and haven’t for years. If the sun gets too high, I put on a shirt and a broad-brimmed hat, or I rest in the shade of a tree. But sometimes – on weekend mornings, when I might stay later at the pool – I see many people spraying or lathering sunscreens on themselves and their children, then jumping straight into the pool. Often, late in the day, it seems as if a skin of sunscreen is floating on top of the pool. Personally, I wish all sunscreen wearers would know to put the screens on before they come to the pool. Let ’em soak in a little! Better protection for the skin and less sunscreen in the water.

Nano-particles in sunscreens are a whole different problem. They are, simply, an unknown. Can the introduction of a manufactured particle – a particle never known in nature – be good for the underwater ecosystem that my city has tried so hard to maintain in our beloved local spring-fed pool? As for your own city pool, filled with chlorinated water, that water has to go somewhere once it’s drained. For my city, I believe it goes back into the city’s water system, ultimately to a wastewater treatment plant, before being discharged back into a local river.

So I have to agree with Friends of the Earth and company. More testing is needed. Meanwhile, nano-particles in sunscreens – which don’t really keep you safer from the sun’s harmful rays – aren’t worth the risk.