Colorful candies or plastic toys are welcome surprises inside a chocolate egg or cereal box, but a strand of hair in our food — not so much.

五颜六色的糖果或塑料玩具在巧克力蛋或麦片盒里是很受欢迎的惊喜，但食物里的一缕头发就不那么受欢迎了。

When it comes to food manufacturing and handling in the United States, the U.S. Food & Drug Administration (FDA) has federal regulations in place for protection against hair contamination, such as "wearing, where appropriate, in an effective manner, hair nets, headbands, caps, beard covers, or other effective hair restraints." However, the FDA does acknowledge that, by nature, some "unavoidable defects" will make their way into our food. For this reason, health officials have established maximum levels of contaminants permitted in food that pose no risk to human health.

在美国食品制造和处理方面，美国食品和药物管理局(FDA)制定了防止头发污染的联邦法规，如“在适当情况下，以有效方式佩戴发网、发带、帽子、胡须套或其他有效的头发约束装置。”然而，FDA承认，从本质上讲，一些“不可避免的意外”会进入我们的食品中。出于这个原因，卫生官员已经确定了食品中允许的对人类健康没有风险的污染物的最高水平。

Believe it or not, one such permitted "defect" is rodent hairs — gasp! But for the time being, let's focus on stray human hairs found in food, and how much of a health threat they may pose.

信不信由你，其中一个允许的“意外”就是啮齿动物的毛发——喘口气!但现在，让我们把重点放在食物中发现的散落的人类毛发上，以及它们可能会对健康造成多大的威胁。

Hair cannot be broken down by the body

头发不能被身体分解

Our hair is composed of a densely packed protein known as keratin, Northwestern University dermatologist and hair specialist Maria Colavincenzo explains to Popular Science. As it turns out, keratin is not digestible by the body (via Hair Max). If you're a cat owner, you've seen this demonstrated by your pet regurgitating a hairball. Although hair cannot be broken down by the body, a strand of it that finds a way down your gullet will simply pass through the body without complication.

西北大学皮肤科医生、头发专家玛丽亚·科拉文佐向《大众科学》杂志解释说，我们的头发是由一种被称为角蛋白的密集蛋白质组成的。事实证明，角蛋白不能被身体消化。如果你是一只猫的主人，你的宠物反刍一个毛球就可以证明这一点。虽然头发不能被身体分解，但一缕头发只要顺着你的咽喉往下走，就会简单地穿过身体而不会出现并发症。

It's good to know that an accidentally ingested strand of hair doesn't pose any risk of a bowel obstruction. But is it sanitary? Colavincenzo says that it's possible for staph bacteria to show up on human hair, but the amount on a single strand is minuscule. To illustrate just how minuscule, Colavincenzo states that any real risk of gastrointestinal problems would come only from consuming "a whole head's worth" of hair (via Popular Science).

很高兴，意外摄入的一缕头发不会造成任何肠梗阻的风险。但是它卫生吗?Colavincenzo说，葡萄球菌有可能出现在人的头发上，但单链上的数量是微乎其微的。为了说明这一点，Colavincenzo指出，任何胃肠道问题的真正风险都只来自于食用“一整头”的头发。

So there you have it. While not the most welcome visitor in your salad or soup, the stray hair accidentally swallowed with your food won't send you running to the hospital or your doctor. It poses so little risk, in fact, that Popular Science reports the FDA has no established regulations regarding the permitted number of strands on a plate. It might be a little gross, but you'll survive that errant surprise.

好了。虽然不是沙拉或汤中最受欢迎的客人，但误食的头发不会让你跑到医院或医生那里。事实上，它所带来的风险非常小，以至于《大众科学》报道说，FDA对于盘子上允许的头发数没有既定的规定。这可能有点恶心，但你会挺过那次意外惊喜的。