Renting sometimes means having to do without a few modern conveniences. You may be bemoaning the fact that your apartment doesn't have a dishwasher — but according to a study by researchers at Sweden's University of Gothenburg, hand-washing your dishes may be giving you (or at least your kids) a leg up over all the folks out there depending on machines.
The researchers conducting the study were looking for ways to test the so-called hygiene hypothesis, the idea that the prevalence of allergies and autoimmune diseases in recent history can be traced to our newfound tendency to hyper-sterilize everything. Expose to dirt and bacteria in early childhood, so the theory goes, teaches your immune system to distinguish properly between harmful and innocuous stimuli, preventing the kind of overreactions that cause things like asthma and hay fever. Basically: living in environment that is too clean could be making you sick.
The researchers wanted to isolate factors that could result in a hyper-clean environment, so they decided to look specifically at the dishwasher. What you've suspected is true: washing your dishes by hand is, in fact, less effective at eliminating bacteria than using a dishwasher. But this could be a good thing. The researchers found, in studying more than 1,000 Swedish families, that children growing up in families who regularly hand-washed their dishes (versus using a dishwasher) were about half as likely to develop allergies.
At the point, a word of caution: there's the old correlation-does-not-imply-causation thing. So the reduced incidence of allergies in the hand dishwashing families could be connected to other factors not considered by the study. And we don't know how increased exposure to bacteria affects adults, although there are definitely people out there who think that's a good thing. Until we learn more, the scientists doing the study don't suggest ditching your dishwasher if you already have one — but if you don't, this might give you an extra twinge of satisfaction as you scrub those plates.
Read the full article (and find a link to the full study, if you're into that kind of thing) at NPR.