Researchers in Sweden have found that children living in households where hand-washing dishes is the norm were significantly less likely to develop allergies, asthma and eczema than children who live in homes where the dishes are washed by machine.
The study, from a team of allergists at University of Gothenburg's Department of Pediatrics, surveyed the families of 1,029 Swedish children. They asked parents about their dishwashing habits and also whether or not their children — most of whom were around age eight — had problems with conditions such as eczema, hay fever or allergic asthma. The team found that children living in families that hand-washed their dishes were about 40 percent less likely to develop allergies than kids in families that used a dishwasher.
Health experts believe that this study lends even more credence to the "hygiene hypothesis," that suggests that kids who grow up in an overly sanitized environment will be more likely to have problems with allergies and other immune system disorders. According to the hygiene hypothesis, kids who grow up in a super-clean environment never develop immunity to germs and bacteria. So when they are exposed to allergens, their bodies respond in full force. Whereas kids who are exposed to small amounts of dirt and bacteria — whether it's from outdoor play or being around pets — develop stronger immune systems than those who never encounter a germ.
Even the most meticulously hand-washed dishes are likely to have more bacteria or food particles left behind than those that are boiled and steamed in a dishwasher. And it's possible that this is just enough exposure to bolster the immune system and prevent allergic reactions from developing.
But before you kick your machine to the curb, there are a few factors to consider. While this new study did take into account the economic status of participants as well as parental history of allergies, the researchers did note that there are lots of other pieces to the puzzle that could influence whether or not these kids develop allergies. For example, it would be interesting to know how many of the kids whose families washed dishes by hand also lived in rural areas. Previous research has shown that kids who grow up on farms and/or kids who play outdoors frequently are less likely to develop allergies.
Factors such as exposure to pets and frequency of eating farm-bought produce also affect the incidence of allergies.
Bottom line: I wouldn't let this one study influence how you do the dishes. But if you are on the fence about purchasing a dishwasher and also concerned about allergies and eczema in your children, this might be a good reason to save some dough.
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