They always strike when least expected — opening the mail, rummaging through notes, and in an instant, it's "ouch!" and you're sucking air in through your teeth.
Oh, the paper cut. Since the dawn of office work, it has been the one thing that can make even the most composed business person spew profanities. Somehow, that little cut stings more than any other nick — and it keeps hurting, too.
But why? Theories of office lore circulate the Internet — from the microscopic structure of paper, to the chemicals used in paper plants, to bacteria living on our faxes.
While dermatologists know which theories are wrong, the most annoying pain in the office still remains a bit of a medical mystery.
"Nobody really knows the answer," says Dr. Joseph Eastern, a dermatologist in private practice in Belleville, N.J. But, Eastern adds, there are a few good theories.
The first culprit would be our hands' nociceptors — the nerve fibers that send touch and pain messages to our brain, particularly the somatosensory cortex.
The hands hog more nociceptors than the arms, the legs, or the stomach, as a way to protect us.
"If we touch something hot or sharp, or in anyway painful, we are most likely to do it with our hands — and so, our hands should be a great judge of those bad or painful things," says Dr. Mark Abdelmalek, chief of laser and dermatologic surgery at Drexel University College of Medicine.
"If you had a paper cut on your thigh, it wouldn't hurt nearly as bad because the thigh doesn't deserve all that attention in the brain's somatosensory cortex," he says.
But the strategic concentration of nerves on our hands doesn't explain why paper cuts instantly sting in a way other scrapes and cuts on our hands do not.
To explain that, people often turn to the weapon — paper.
Internet forum posts are full of blame for paper, and most are a little off the mark.
One frequent claim is that paper is porous, and therefore, a better host to bacteria than the clean surface of a razor or a knife. Cut yourself with paper, and you'll leave behind debris and bacteria to sting you.
But dermatologists don't always agree.
"Number one, bacteria don't cause pain," says Eastman. "You get pain with an infection, because your skin is inflamed, trying to fight off bacteria, but bacteria doesn't cause pain."
Second, says Eastman, "I don't know that there's any evidence that paper leaves behind more dirt and bugs than anything else you cut yourself with."
However, paper is still part of the problem. Paper is sharp, but it's duller than knives and razors. It's also more flimsy than needles and rocks. Unfortunately, for office workers, the combination of paper's unique qualities results in awful cuts.
The flexible, relatively dull edge of paper means paper cuts never go very deep. But while a dull, shallow cut sounds less painful, pain specialists say it's worse.
First, the dull edge of the paper is more likely to rip flesh than tear it. "This means paper could do more microscopic damage," says Eastman.
The microscopic damage hits the most sensitive nerves, too. The concentrated nerves on the hands have a very low threshold to activate and send a signal to the brain, says Dr. Carmen R. Green, associate professor of pain medicine at the University of Michigan.