How clean must clean be?

The latest blow to conventional wisdom arrives courtesy of Paul Dawson. He’s a food scientist at Clemson University whose work takes a broad swing at the popular notion of the “five second” rule for food items dropped and quickly retrieved from the ground.

His findings indicate that the amount of time a fallen item can reside on a kitchen floor before being deemed unsafe to eat is … zero! That’s right, no amount of brushing or frantic blowing stands a chance against the potentially dangerous bacteria that he believes instantaneously contaminate fumbled food.

According to Dawson, it’s all about location — with no measure of time offering safe harbor against the nearly four-week life span of salmonella and other bacteria that reside on kitchen floors.

Same goes for the bathroom, where gastrointestinal illness is a too-likely outcome for those engaging in the risky behavior of eating anything dropped there. (Then again, perhaps eating in the bathroom is an activity best avoided entirely — for reasons well beyond those in the food safety realm.)

It’s important to note that others in the greater scientific community offer an opposing view on the issue of contaminating bacteria. Some actually believe that germs shouldn’t be so scrupulously avoided, given the significant role they can play in building human immune systems, especially in young children.

Given the conflicting data, we invited Dr. Gary Goldbaum of the Snohomish Health District to weigh in on the concept and potential for safe application of a five-second rule.

His approach is both measured and practical. Noting that while every instance is unique, and has an inherent potential for trouble, “you can’t go wrong if you apply common sense as your guiding factor.”

Goldbaum also offered an important reminder that “nature provided us with remarkably effective defenses against infection and that we really ought not worry overly much about consuming an occasional dropped item.”

Behavioral studies offer other interesting observations on the application of the five-second rule. One is that women are more likely then men to retrieve a dropped item and serve it to their family or guests. And, in a clear statement of the obvious, individuals are more likely to recover and consume an item if no one is looking, or, if the dropped object is deemed far too tasty to waste. Cauliflower: to the trash. Chocolate: into the mouth.

Conventional wisdom is nothing if not practical.