雙語：肥皂會變髒嗎？

Can Soap Get Dirty?

肥皂會變髒嗎？

When you see lovely little bars of lemon-thyme or lavender hand soaps on the rim of a sink, you know they are there to make you feel as fresh as a gardenia-scented daisy. We all know washing our hands is important, but, like washcloths and towels, can the bars of hand soap we use to clean ourselves become dirty as well?

當你看到水池邊可愛的檸檬百里香或薰衣草香皂時，你就知道它能讓你感受到如梔子花香的雛菊般清新動人。衆所周知，洗手很重要，但就像毛巾一樣，我們用來清潔雙手的洗手皁也會變髒嗎?

Soaps are simply mixtures of sodium or potassium salts derived from fatty acids and alkali solutions during a process called saponification. Each soap molecule is made of a long, non-polar, hydrophobic (repelled by water) hydrocarbon chain (the "tail") capped by a polar, hydrophilic (water-soluble) "salt" head. Because soap molecules have both polar and non-polar properties, they're great emulsifiers, which means they can disperse one liquid into another.

肥皂僅僅只是由脂肪酸和鹼溶液在皂化過程中產生的鈉鹽或鉀鹽的混合物。每個肥皂分子都是由一個長而非極性的疏水(被水排斥)碳氫化合物鏈(“尾巴”)和其頂端的一個極性親水(水溶性)碳氫化合物鹽鏈構成。由於肥皂分子具有極性和非極性的特性，它們是很好的乳化劑，這意味着它們可以將一種液體溶解到另一種液體中。

When you wash your dirty hands with soap and water, the tails of the soap molecules are repelled by water and attracted to oils, which attract dirt. The tails cluster together and form structures called micelles, trapping the dirt and oils. The micelles are negatively charged and soluble in water, so they repel each other and remain dispersed in water—and can easily be washed away.

當你用肥皂和水洗手時，肥皂分子的尾部會被水排斥，並被帶有污垢的油脂所吸引。尾部聚集在一起，形成一種叫做膠束的結構，可以吸附灰塵和油脂。這些膠束帶負電荷，可溶於水，因此它們相互排斥，並分散在水中，極易被沖走。

So, yes, soap does indeed get dirty. That's sort of how it gets your hands clean: by latching onto grease, dirt and oil more strongly than your skin does. Of course, when you're using soap, you're washing all those loose, dirt-trapping, dirty soap molecules away, but a bar of soap sitting on the bathroom counter or liquid soap in a bottle can also be contaminated with microorganisms.

因此肥皂確實會變髒。這就是它清潔雙手的方法：它能比皮膚更強地附着在油脂和污垢上。當然，當你在使用肥皂的時候，你是在清洗那些不規則分佈、能吸附灰塵的髒肥皂分子，但是放在浴室臺上的一塊肥皂或裝在瓶子裏的液體肥皂的確可能被微生物污染。

This doesn't seem to be much of a problem, though. In the few studies that have been done on the matter, test subjects were given bars of soap laden with E. coli and other bacteria and instructed to wash up. None of the studies found any evidence of bacteria transfer from the soap to the subjects' hands. (It should be noted that two of these studies were conducted by Procter & Gamble and the Dial Corp., though no contradictory evidence has been found.)

不過，這似乎不是什麼大問題。在對這一問題進行的爲數不多的研究中，研究人員給受試者提供了含有大腸桿菌和其他細菌的香皂，並指示他們洗手。沒有一項研究發現任何證據表明細菌會從肥皂轉移到實驗對象的手上（值得注意的是，其中兩項研究是由寶潔公司和戴爾公司指導，但沒有發現相互矛盾的證據）。

Dirty soap can't clean itself, though. A contaminated bar of soap gets cleaned via the same mechanical action that helps clean you up when you wash your hands: good ol' fashioned scrubbing. The friction from rubbing your hands against the soap, as well as the flushing action of running water, removes any harmful microorganisms from both your hands and the soap and sends them down the drain.

然而，髒肥皂不能自潔。一塊被污染的肥皂可以通過洗手時清潔的相同機械作用得到清潔：良好的傳統擦洗。雙手與肥皂摩擦產生的摩擦力，以及自來水的沖洗作用，會清除手上和肥皂上的有害微生物，使其流入下水道。

翻譯：MS小冰晶