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Hey podcast listeners. As you know, we like to take questions from just about anybody — readers, listeners, strangers in the street. Sometimes we’ll go out on a limb for a question — literally, out on a limb. Like the other day, I was just looking out my window, and this pigeon — he looked familiar but honestly, they all look alike to me — he just started yapping away …

Stephen J. DUBNER: What’s that?

DUBNER: Huh. You know, I do remember that.

DUBNER: Yeah, that’s a great question — whatever did happen to the carpal-tunnel syndrome epidemic?

From WNYC this is Freakonomics Radio, the podcast that explores the hidden side of everything. Here’s your host, Stephen Dubner.

DUBNER: So Levitt, I remember when we first met. I was at your office at University of Chicago, and your computer had one of those keyboards that sort of folded up in the middle. You type kind of like you’re playing a concertina, one of those little push-button accordions. So what was that all about?

LEVITT: Oh, man. Carpal tunnel. So when I was a graduate student, I decided to type in the data from every congressional election that had ever occurred in the United States. And I got these big books. And I had this horrible typing setup. Now, this was back in about 1990, 1991. There was barely Internet. So, here I was. I type in this data. I got really good. I used my right hand and a keypad. And I got to be tremendously fast. And after about 10 hours straight of doing that, I get off the computer, and boy man, my wrist would be tired.  But I think, “Well, just tired.” I would do it day after day after day. It probably took me two weeks to type in all the data. By the end of the two weeks, my wrist ached and throbbed and was numb and I couldn’t sleep at night. I thought this will go away. And I never heard of carpal tunnel. So I figured it was nothing. Seven years later, I was still sleeping with my arm dangling off the bed. I mean you knew me. When you first met me, I couldn’t open a can of pickles to save my life. My right wrist was totally debilitated. And the irony of the whole thing is that as soon as I finished typing the data, I ran into a professor at Harvard who said, “Oh, you just typed in that data? I’ve already had all that key punched. I could just give it to you.”

DUBNER: So there was a period right around the time that you were, as a grad student, were doing all this data entry, I was starting out in journalism, and you’d walk into any newsroom at the time, you walk into the New York Times, and it’d look kind of like a polio ward. All these people with braces, and all these set-ups. And they’re sitting. And the ergonomics department was having a great period of activity, because it was a … it felt like an epidemic. Where’d it go?

LEVITT: Yeah, great question.

LEVITT: I think partly, once people knew about the damage, when it started to hurt, they stopped. They changed their set-up. Partly a lot of it was probably psychosomatic, right? Once everyone talks about how some problem — it’s a great way to get out of work, right? Just skip a few weeks of work by saying, “Now I can’t type on the keyboard for a few weeks.” Um, I don’t know, maybe people don’t work as hard as they used to. Maybe they spend all their time clicking around on Facebook when they’re supposed to be typing up their stories at The New York Times? That’s another possibility.

All right, plainly Steve Levitt doesn’t know the answer to this question. So let’s try to find someone who does. Someone who can explain why, with so many more people typing and texting these days, the average office no longer looks like a polio ward.

Dr. Bradley EVANOFF: And actually, if you give me license I’ll take the story back to 300 years before that.

That’s Bradley Evanoff. He’s an M.D. and professor at Washington University in St. Louis, and he specializes in occupational medicine.

EVANOFF: The first textbook of occupational medicine is written by an Italian physician, Bernardino Ramazzini, who was working in Padua in the late 1600’s and early 1700’s. So he writes this book called Diseases of Workers. And he describes in this wonderful 18th century prose how work can be harmful to you. And I’ll read the first line just because we don’t write medical texts like this anymore. But he says, “Various and manifold is the harvest of diseases reaped by certain workers from the crafts and trades that they pursue. All the profit that they get is a fatal injury to their health.” So he describes two main causes of occupational injury. And one of his causes here he says, “There are certain violent and irregular motions and unnatural postures of the body. And that these result in serious diseases that gradually develop.”

So, one such disease is what eventually comes to be known as carpal-tunnel syndrome. That’s what happens when a nerve that runs through your carpal tunnel — which is at the base of your hand — gets pinched or squeezed. It’s easy to see how that might happen if you’re shoeing a horse for 12 hours a day in 18th century Italy. Let’s fast-forward to the early 20th century. The same idea was advanced by a New York surgeon named Harry Finkelstein. Here’s Evanoff again:

EVANOFF: And he’s surrounded by patient populations that are working in the garment district and is probably just more aware of work and including housework and women’s work. He describes sort of wringing clothes and chopping wood and doing other hand-intensive tasks even that are occurring in the home. And so Finkelstein in talking about hand tendonitis makes no bones about the fact that he thinks that chronic trauma from hand intensive activities are a major cause and at one point says the laboring classes are most frequently affected.

So, no dispute there. The cause of the problem is “violent and irregular motions and unnatural postures” among certain kinds of workers. But then the story gets more complicated. Another surgeon, George Phalen at Cleveland Clinic, comes along and helps to develop the operation that becomes standard for people who suffer from carpal-tunnel syndrome. So his opinion carried weight. Which is a problem, because — as Bradley Evanoff tells it — Phalen’s opinion is kind of … off.

EVANOFF: So, he is ardently convinced that work is not a causal factor for carpal tunnel syndrome and repeatedly refers to it as an “idiopathic” cause. And idiopathic is Latin for we don’t know.

DUBNER: Why did Phalen think the cause was idiopathic? Perhaps because a lot of his patients were women.

EVANOFF: He basically says women don’t do heavy work with their hands. I didn’t see very many men, of the men I saw, only one had hand activity that he thought was abnormal or out of the range. He said, “Look most of it occurs with women and women don’t do any of the heavy work, it’s not work-related.”

So, for many years that was the prevailing view, that carpal-tunnel syndrome was this murky, real-but-not-quite-real affliction. But then, in the early 1970’s, the Occupational and Safety Health Administration, or OSHA, was founded.

EVANOFF: And so they very early on started reporting on the high rates of hand and wrist problems that were seen in some occupations and trades. And then I think there were also economic forces in the ’70s and ’80s that probably did increase the actual rate of carpal-tunnel syndrome. And these were in manufacturing and meatpacking in a number of industries it’s reported that the line speeds had increased.

So, for the first time, work-related injuries, like hand and wrist pain, were not only reported and tracked — but were eligible for compensation.

EVANOFF: So, I think that prior to around 1985 or so there are really very few cases of carpal tunnel syndrome that are paid for out of workers compensation. And then you see this big growth between 1985 and about 1995 where many more cases are claimed as work related. And this is the so-called epidemic of carpal tunnel syndrome that got people quite interested in and focused on CTS in the late 80’s early ’90s.

Coming up on Freakonomics Radio: how big was the carpal tunnel epidemic? And was the spike really due to the arrival of the computer keyboard?

EVANOFF: I think it is mostly a misconception.

ANNOUNCER: From WNYC: This is FREAKONOMICS RADIO. Here’s your host, Stephen Dubner.

DUBNER: Today we’re trying to answer a question that a friend asked about carpal-tunnel syndrome, and how it seemed to become an epidemic when offices started using lots of computers. I saw this firsthand in the mid-1990s, when I was working at The New York Times. Here’s Bradley Evanoff, a professor of medicine at Washington University.

EVANOFF: So there were several newsrooms where there were a couple of cases of carpal tunnel syndrome. And I think this got a lot of attention in the journalistic world. And I think probably helped promote the keyboard as the main source of exposures that were relevant to carpal tunnel syndrome, when in fact it would be much better to work as a journalist than to work as a meat-packer.

The notion that office workers are particularly prone to carpal-tunnel syndrome is, according to Dr. Evanoff, largely false:

EVANOFF: I think it is mostly a misconception. There are some types of keyboard jobs that are at a high risk for carpal tunnel syndrome. And this would be people who are transcriptionists or data entry people where all they do for eight hours a day is pound the keyboard. Most people working in office settings are not in a keying position where they’re continuously keying for an entire day. And in fact in our studies, the office or clerical workers are actually the low risk group with whom we’re comparing these construction or manufacturing workers, we’re comparing this high risk group to the office group, the group at lowest risk.

The number of carpal-tunnel cases that qualify for workers’ compensation peak in the mid-1990s, Evanoff says.

EVANOFF: … and then drops off really sharply after that.

But that hardly means that carpal-tunnel syndrome has gone away. Overall, Evanoff says that between 1 and 2 percent of American workers today suffer from it — and the numbers are much higher in certain fields:

EVANOFF: Right, so if you look at constructions workers, you may find that 5 to 8 percent have carpal tunnel syndrome. Some of the highest reported rates have been in manufacturing and food processing. And there are some food processing jobs where if you go in and examine all the workers you may find that up to 20 percent have carpal tunnel syndrome. I think the slaughterhouses and the meatpacking plants have some of the highest exposures. They come in squawking at one end and go out wrapped in cellophane at the other end.

EVANOFF: You can imagine the kind of handwork that is involved in cutting up 2,000 chickens an hour or cutting up a cow into its constituent pieces. Other types of food processing are dairy, some vegetable picking and processing, anything that requires people to grab something, move it, twist it, cut it, pack it, stack it, pull it. And to do that thousands of times a day is a job that is at high risk of carpal tunnel syndrome as well as for other disorders of the hand and wrist like tendonitis or epicondylitis.

So, carpal-tunnel syndrome is, unfortunately, alive and well. Among construction workers and food-processing workers, among chefs and professional musicians. Even among some journalists here and there. But it no longer captures the attention of journalists — and, therefore, you no longer hear about it so much. Journalists, as you probably know, we love to write about ourselves. So if carpal-tunnel syndrome isn’t happening so much in the newsroom — well, if a tree falls in the forest, and no one’s around to hear it, does it make a sound?

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