Dear Cecil: I've always heard that dentists have the highest suicide level of any of the medical professions, but I've never believed it. Is there any truth to it? Terey Allen, Trenton, Michigan

Cecil replies:

This is one of those dodgy things that “everybody knows.” And not just the uninformed public, either — dentists themselves believe it. Since the 1960s dental journals have been carrying articles with headlines like “The Suicidal Professions.” Dozens of studies have looked at suicide not only among dentists but among health-care workers in general. With few exceptions, research over the past 40 years has found that dentists (and doctors) take their own lives at a higher-than-average rate. But how much higher? To hear some tell it, you’d better not leave these guys in a room alone.

Dentists’ odds of suicide “are 6.64 times greater than the rest of the working age population,” writes researcher Steven Stack. “Dentists suffer from relatively low status within the medical profession and have strained relationships with their clients — few people enjoy going to the dentist.” One study of Oregon dentists found that they had the highest suicide rate of any group investigated. A California study found that dentists were surpassed only by chemists and pharmacists. Of 22 occupations examined in Washington state, dentists had a suicide rate second only to that of sheepherders and wool workers.

But the sheer diversity of results has to make you suspicious. I mean, which is it — dentists, chemists and pharmacists, or sheepherders and wool workers? (What, the bleating gets to them?) And what about psychiatrists? One school of popular belief holds that they have the highest suicide rate.

Read the studies and you begin to see the problem. Suicide research is inherently a little flaky, in part because suicides are often concealed. Equally important from a statistical standpoint is the problem of small numbers: dentists represent only a small fraction of the total population, only a small fraction of them die in a given year, and only a small fraction of those that die are suicides. So you’ve got people drawing grand conclusions based on tiny samples. For example, I see where the Swedes think their male dentists have an elevated suicide rate. Number of male-dentist suicides on which this finding is based: 18.

But you aren’t reading this column to hear me whine about the crummy data. You want the facts. Coming right up. All we need to do, for any occupation of interest, is (a) find a large, reasonably accurate source of mortality statistics, (b) compute suicides as a percentage of total deaths for said group, and (c) compare that percentage with some benchmark, like so:

PERCENTAGE OF DEATHS DUE TO SUICIDE U.S. white male population 25 and older (1970): 1.5 U.S. white male dentists (1968-72): 2.0 (85 of 4,190) U.S. white male medical doctors (1967-72): 3.0 (544 of 17,979) U.S. white male population 25 and older (1990): 2.0 U.S. white male medical doctors (1984-95): 2.7 (379 of 13,790) (Sources: Vital Statistics of the United States — 1970, National Center for Health Statistics, Table 1-26, “Deaths from 281 Selected Causes, by Age, Race, and Sex: United States, 1970”; death certificates from 31 states, reported in “Mortality of Dentists, 1968 to 1972,” Bureau of Economic Research and Statistics, Journal of the American Dental Association, January 1975, pp. 195ff; death reports collected by the American Medical Association, reported in “Suicide by Psychiatrists: A Study of Medical Specialists Among 18,730 Physician Deaths During a Five-Year Period, 1967-72,” Rich et al., Journal of Clinical Psychiatry, August 1980, pp. 261ff.; Vital Statistics of the United States — 1990, National Center for Health Statistics, Table 1-27, “Deaths from 282 Selected Causes, by 5-Year Age Groups, Race, and Sex: United States — 1990”; National Occupational Mortality Surveillance database, reported in “Mortality Rates and Causes Among U.S. Physicians,” Frank et al., American Journal of Preventive Medicine, Vol. 19, No. 3, 2000.

I know what you’re thinking. Percentages! They’re so primitive! What about the Poisson distribution, the chi-square test, the multivariate regression analysis? Not to mention the fact that I don’t express suicides relative to 100,000 living population; that I haven’t corrected for age distribution, socioeconomic status, etc; and that I couldn’t find any current data for dentist mortality in the readily available literature. Sue me. We’ve got enough here to draw some basic conclusions.

Suicide among white male American dentists is higher than average but not as high as among white male American doctors. (Sorry to limit this to white men, but that’s all the data I had to work with.) Don’t fret, though. Dentists’ death rates from other causes are lower, and on average they live several years longer than the general population. Ditto for doctors.

What’s the most suicidal occupation? I won’t venture an opinion for the world of work overall, but among health-care types it may well be shrinks. In a study of 18,730 physician deaths from 1967 to 1972 (men and women), psychiatrists accounted for 7 percent of the total but 12 percent of the 593 suicides (source: Rich et al., cited above).

Even more alarming is the rate of suicide among female doctors. A recent study found that 3.6 percent of white female doctors’ deaths were suicides — higher than the rate for male doctors and many times the average for U.S. women (0.5 percent for 1990; source: Frank et al., cited above; Vital Statistics of the United States — 1990). Women have entered medicine in huge numbers in recent decades, but progress has come at a price.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.