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.
We get our daily dirt allowance in all kinds of ways, from contaminated food, dust inhalation, and from not washing our hands before eating. The Environmental Protection Agency (EPA) has compiled an enormous amount of research on dirt consumption. About 45 percent of the stuff we inhale or inadvertently eat is soil, and 55 percent is dust.
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. If you take those daily numbers and make them annual, that would be 36,500 milligrams or 1.3 ounces per year.
Kids, as we all know, just love eating dirt, especially between the ages of 1 and 3. One researcher theorized that although childhood dirt-eating certainly is based in curiosity about the world and the new ability to play and grab, it could also be an effort to get some vitamins and minerals. Purposeful dirt-eating usually happens around a year old, which is when many babies stop breastfeeding, so maybe they're trying to regain some of that nutrition.
众所周知，孩子就喜欢吃灰尘，尤其是1-3岁的孩子。一个研究人员系统地 指出，虽然儿童时期吃灰尘绝对是出于对世界的好奇，孩子也在锻炼玩和抓的新能力，但这种行为也能使孩子吸收一些维生素和矿物质。有意识地吃土通常发生在一 岁左右，这时很多孩子断了母乳，他们可能是在努力摄取一些母乳中的营养。
However, some people keep eating dirt after early childhood, a condition called geophagy, or soil pica (pica is the habit of eating nonfood items). In American culture, geophagy is regarded with concern. Pica, in fact, is a recognized disease by the U.S. Agency for Toxic Substances and Disease Registry, with intentional dirt consumption of 500 milligrams a day qualifying as "pathological". But historically, and 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.
然 而一些人过了幼儿期还会吃土，这种情况被称为食土癖或土壤异食癖（异食癖就是吃非食物东西的习惯）。在美国文化中，食土癖使人们很担心。其实异食癖是被美 国有毒物质和疾病登记处认定的一种疾病，每天有意识地吃掉500毫克土就被认定为“病态”。但从历史上看，在很多其他文化中吃土没那么怪，也不算病态。一 些撒哈拉以南非洲的孕期妇女吃土来缓解晨吐时肠胃不适或补充胎儿生长所需的额外营养。
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, right?