Do childhood germs make for healthy adults?

And other recent highlights from the Ideas blog

In an interesting article on the rise of the pervasive hand sanitizer Purell in the March 4 issue of The New Yorker, author David Owen quotes a food expert with a startling perspective on human health.

The expert is Don Schaffner, a food microbiologist at Rutgers. He says that germophobia in rich countries like the United States leads to weaker adult immune systems and has a negative impact on long-term health. Here’s the quote:

“We might have a much healthier population if we adopted the kinds of conditions that we see in many Third World countries, with poor-quality food and poor-quality
water and lots and lots of germs. If we did that, we would have very healthy and very strong immune systems. Unfortunately, the price that we would pay would be extremely high infant mortality. That’s the trade-off.”


The broad idea he’s talking about is known as the “hygiene hypothesis.” It has a strong counterintuitive appeal—fighting disease makes your body healthier!—and has been particularly influential in certain corners of American parenting, where a lack of early exposure to germs is blamed for many modern woes, including autism.

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But is it true? As it turns out, a number of well-respected studies have found that poor health in childhood is highly correlated with poor health in adulthood. A 1998 study by Samuel Preston at the University of Pennsylvania looked at a large group of African-Americans born at the beginning of the 20th century. He found that the children who grew up in the least healthy environments were the least likely to survive to age 85. A 2007 study by Steven Haas at Arizona State University came to similar conclusions.

Perhaps the hygiene hypothesis has it backward, and exposure to disease in childhood leads to permanent health handicaps as people age. That’s the argument of a 2004 paper published in Science titled “Inflammatory Exposure and Historical Changes in Human Life-Spans.” The authors hypothesize that childhood infections cause a buildup of inflammation in the body, which leads to poorer health in adulthood. To support this argument, they cite a number of studies that have shown that greater exposure to infections in childhood is associated with higher rates of cardiovascular and respiratory diseases, cancer, and diabetes later in life.

I e-mailed Schaffner about all this, and he promptly backed away from his quote in The New Yorker, explaining that his was an “off the cuff” comment pertaining to a field where he’s not an expert (“I’m a food microbiologist, not a child health/mortality expert”). He also said that while cleanliness may have fewer downsides than he thought, the idea that illness in childhood promotes health in adulthood still seems “sensible” to him.

It makes a certain kind of intuitive sense that whatever doesn’t kill kids makes them stronger. But evidence suggests that childhood germ exposure likely comes at a lifelong cost.



It’s hard to believe, but these striking images actually existed for a moment in real life. The Japan-based group Fiz-Iks uses long photographic exposures and an arsenal of light sources—different types of flashlights, colored filters, and a great variety of glow sticks—to create evanescent shapes everywhere from

Trevor Williams

ancient Eastern temples to corporate galas. Light painting has been a catchy art form for a long time (in one of the most famous early examples, in 1949, Picasso created mid-air light figures), but Fiz-Iks takes the art form to 21st-century extremes. A tutorial on their website shows the tools they use, which include “light stencils,” through which they stamp many of their images with a tiny, projected blue bird.

Kevin Hartnett is a writer who lives in Ann Arbor, Mich. He can be reached at