September 28, 2005--I'm Gonna Wash That Man . . .

I don’t quite know how to bring this up in mixed company, but in the spirit of science and truth, I will force myself to do so.

The NY Times Science Times Section yesterday reported that though 91 percent of Americans say they always wash their hands after using public toilets, only 83 percent actually do so, according to an observational study (see link below—click on “Original Article”).

First just the facts: In a nationwide poll conducted by Harris Interactive, 1,013 adults were interviewed; that’s how they got to the 91 percent. Suspecting this might not capture the whole truth, a second study was commissioned by the American Society for Microbiology and the Soap and Detergent Association (more about them in a moment). For this study, 6,336 adults’ toilet behavior was observed in the field; that’s how they came up with the 83 percent.

Any serious student of science wants to know about methodology, and since I had a few questions I made a few inquiries—

(1) How did they come up with 6,336 to be observed when they interviewed just 1,013?

(2) Where did they do the observing?

(3) Who did the observing?

(4) Were there statistically significant differences in washing behavior between those with just a high school education and college graduates and/or between higher and lower income urinators?

(5) Were there any differences in the post-potty-hand-washing activities of men and women? In other words, is this a gendered situation?

(6) Were there observed divergences between those doing Number One and Number Two?

(7) And, perhaps most important, did any of those who did the observing misbehave or get arrested?

I’m not that much of a researcher and thus I cannot comment on the “N,” the delta in the number interviewed and observed. I can report though that the observing took place in six locations, including Turner Field in Atlanta; the Museum of Science and Industry and the Shedd Aquarium in Chicago; Grand Central and Penn Stations in New York City; and, and at the Ferry Terminal Farmers Market in San Francisco (I won’t even begin to tell you what else they observed there).

I cannot say who did the observing (that was not noted), but from my own research, reading the full report, I can pass along that:

"Observers discreetly watched and recorded whether or not adults using public restrooms washed their hands. Observers were instructed to groom themselves while observing and to rotate bathrooms every hour or so to avoid counting repeat users. Observers were also instructed to wash their own hands no more than 10% of the time." ("Women Better at Hand Washing Hygiene Habits, Hands Down," American Society for Microbiology, September 21, 2005)

This suggests the observers must have been out of work actors.

And yes, as one would expect, the findings are in fact gendered and SES-correlated: woman “were more diligent than men”—90 percent washed their hands as compared with only 75 percent of men; and poorer, less educated men and women were also less diligent. If you are curious about different rates of diligence between, say, the Turner baseball stadium and San Franciscans, you will probably not be surprised to learn that just 74 percent of fans washed up while 88 percent did in the City By the Bay.

So what besides prurience might be the bottom line? As noted above, this study was largely financed by the Soap Association. Could there be a little self interest at work here? (Recall all the “scientific studies” commissioned by Phillip Morris.) Up to now, I had been led to believe that because more colds are spread through handshakes than anything else, it is important to wash ones hands frequently, especially during the flu season.

But what’s the issue about washing after peeing? OK, food handlers I can understand. But what’s the science-based, public health urgency about washing up after handling that other equipment?

Maybe for once, just this once, men have it right.