什么，你每天都吃灰？！為什么自己不知道？那一年下來，你吃了多少呢？

We all know we shouldn’t eat dirt， but we do it anyway. Mostly not on purpose — dirt gets into our bodies all day， every day， whether we want it to or not. It’s understandably difficult to figure out exactly how much is getting in， but that might be beside the point. As one author of a dirtconsumption study noted， "Other than water， what little stuff we humans have inside us is largely dirt ... Most solids that make up humans and other creatures either are now or recently were dirt ... transformed by sunlight into plants or animals."

The Environmental Protection Agency （EPA） has compiled an enormous amount of research on dirt consumption. The EPA numbers on unintentional dirt consumption focus on children， with one study reporting that babies from 6 weeks to 1 year old generally get 60 milligrams a day. From ages 1 to 20， that amount goes up to 100 milligrams a day. （For reference， 50 milligrams equals one-sixth of an aspirin tablet. So we’re not talking all that much dirt）. If you take those daily numbers and make them annual， that would be 36，500 milligrams or 1.3 ounces per year. Again， not a totally horrifying amount.

Historically， in many other cultures， it’s not so odd or abnormal to eat dirt. Some pregnant women in sub-Saharan Africa eat dirt to soothe stomach upsets during morning sickness or to add extra nutrients to the developing fetus’ body.

So while there’s definitely cause for concern about contaminated food and soil， maybe we don’t need to worry so much about inadvertent dirt consumption. It’s only natural， and we’re all made of dirt anyway， right？