Can You Get Lung Cancer from Breathing Too Much Oxygen?

Just about everything will give you cancer these days. The condoms you're using? Cancer. That plastic water bottle you're drinking from? Cancer. Your shampoo, your makeup, your household cleaning products? Cancer, cancer, cancer. It seems like the only pure, non-carcinogenic thing left in the world is the very air we breathe.

But no, not even the air is safe. All that oxygen you're inhaling is slowly poisoning you, according to a new study published in the journal PeerJ that links higher oxygen levels to incidences of lung cancer.

When oxygen metabolizes inside your body, it creates a byproduct called "reactive oxygen species," or ROS, and too much of it can result in damage to your cells and damage, DNA damage, and something called lipid peroxidation (for a sciencier explanation, see here). It can also contribute to the formation of tumors.

At higher altitudes there's less oxygen in the air, of course, which is why athletes who aren't used to it have a hard time competing in those environments. The PeerJ researchers analyzed the incidence of cancer in 250 counties in the United States with varying altitudes—and lung cancer, they found, was negatively correlated with elevation. For every kilometer above sea level, lung cancer incidents decreased by 7.23 per 1,000 individuals. That's significant.

They drew these conclusions after controlling for other factors that contribute to lung cancer—smoking, obesity, exposure to radon—and other factors that are influenced by elevation, like exposure to sunlight and pollution. They also studied the effect of elevation on the three other most common types of cancer—breast, colorectal, and prostate—and found that it was only lung cancer that was significantly affected by oxygen levels. That last bit suggests that it's the process of inhaling oxygen, not just being in a higher altitude, that's carcinogenic.

So, what does it mean? As the study puts it, "Were the entire United States situated at the elevation of San Juan County, Colorado (3,473 meters), we estimate 65,496 fewer new lung cancer cases would arise per year."

Time to run for the hills? Kamen Simeonov, one of the study's co-authors, told me that "people shouldn't be making life decisions based off this research," since all they've established so far is that "there's a trend with lung cancer and elevation, and it's atmospherically dependent." But if you're one of those people who religiously avoids all known carcinogens, then maybe it's worth considering a house upon a hill (as long as it's not in a city, because the polluted air there will give you cancer too.)

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