A Straight Dope Classic from Cecil's Storehouse of Human Knowledge

Do fluorescent lights cause cataracts?

March 15, 1996

Dear Cecil:

A friend of mine, who is paranoid about everything, recently told me that fluorescent lights cause cataracts. Everything I've read about these lights before talks about them glowingly — they're so energy efficient I should replace every lamp in my home with fluorescent bulbs. And of course I and millions of other people toil under them for most of our waking hours every day. Are we all going to go blind? Why have I not heard about these harmful effects before? Is my paranoid friend nuts too, or is there some conspiracy to keep this information out of the press and away from the general public?

Cecil replies:

If there is, my payoff from the Bulb Trust must have gotten lost in the mail. The reason you haven't heard much about the dangers of fluorescent lighting is that there isn't much to hear. No study has ever established a link between fluorescent lights and cataracts, and there haven't been many studies period. While fears about the bulbs aren't entirely groundless, right now the danger is strictly theoretical.

Concerns about fluorescent lights are a byproduct of research into the harmful effects of ultraviolet radiation from the sun. Laboratory experiments have shown that UV light can damage the proteins and enzymes found in the lens of the eye, and several studies have suggested that outdoorsy types and others who get more sun than average are at greater risk for cataracts.

Fluorescent bulbs generate UV light too — that's how they work. When you turn on the juice, a mercury arc in the bulb emits UV light that strikes a phosphor coating on the inside of the tube. The phosphor in turn emits visible light.

The amount of UV emitted by bulbs is a lot less than what the sun puts out, but the fact that many people work under fluorescent fixtures day after day has stirred fears about the long-term effects. Not to worry, the experts say. The amount of UV that escapes from the tube is minimal, since the phosphor absorbs much of it and the glass tube is opaque to most of the rest. Supposedly you receive as much UV from one hour's exposure to sunlight in November in New York City as you do from an entire year's exposure to a fluorescent tube. What's more, the ultraviolet light emitted by the tubes is mostly in the UVA range rather than the more dangerous UVB range.

Concerns about the sun are more urgent. The danger of ultraviolet light remains controversial and given the difficulty of epidemiological studies may never be definitely settled. But enough is known to warrant such basic precautions as wearing sunglasses outdoors. The wraparound kind are especially recommended, one of the few times when being hip is actually good for you.

Just one thing — make sure your sunglasses block UV light. A cheesy pair that blocks only visible light could make things worse. The reduced visible light will cause your pupils to dilate, allowing the UV to pour in. To avoid frying your lenses like an egg, make sure any sunglasses you buy have a tag or label that says they block UV.

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