第2859期:Is your showerhead as clean as you think?

This is a city like no other. An invisible army of microbes live here, including bacteria, fungi, moulds and mites, and it's the one place you'd have hoped would be clean – your showerhead.这是一座与众不同的“城市”。这里住着一支看不见的微生物大军，包括细菌、真菌、霉菌和螨虫，而这地方正是你最希望保持干净的地方——你的淋浴喷头。If you unscrew it and take a peek inside, you might be surprised as to what you find – quite possibly a slimy dark biofilm. When you switch on the shower, it's not just steam and water that come out, but a blast of microbes as well.如果你把喷头旋开往里看，你可能会被里面的东西吓一跳——很可能是一层黏糊糊的暗色生物膜。当你打开淋浴时，不只是蒸汽和水喷出来，还有一阵微生物被一起喷出。Rob Dunn, an evolutionary biologist from North Carolina State University, calls showerheads extreme environments because they are either bone-dry or soaking wet. Once you've showered, the head remains warm and dries out undisturbed, creating the perfect ecosystem for bacteria to feed on dissolved nutrients from the water.北卡罗来纳州立大学的进化生物学家 Rob Dunn 称淋浴喷头是一种“极端环境”，因为它们要么完全干燥，要么完全湿透。洗完澡后，喷头保持温暖并在无人打扰的情况下慢慢变干，这为细菌提供了完美的生态系统，它们可以靠水中溶解的养分生存。It seems the majority of us don't need to worry about catching a bug from having a shower though. "Only showers contaminated with Legionella and other opportunistic pathogens pose a risk," says Frederik Hammes, a drinking water microbiologist at the Swiss Federal Institute of Aquatic Science and Technology in Switzerland.不过，大多数人似乎不需要担心因为洗澡而感染细菌。瑞士联邦水科学与技术研究所的饮用水微生物学家 Frederik Hammes 表示：“只有被军团菌等机会性致病菌污染的淋浴喷头才会构成风险。”Meanwhile, one study in the US found that warmer areas, like Florida and Hawaii, with higher chlorine levels tend to have more pathogenic mycobacteria, which can lead to higher rates of a chronic lung infection called non-tuberculous mycobacteria (NTM) lung disease.同时，美国的一项研究发现，在佛罗里达、夏威夷等温暖地区，水中氯含量较高的地方往往含有更多致病性分支杆菌，这可能导致一种名为“非结核分枝杆菌（NTM）肺病”的慢性肺部感染发病率更高。This is likely because the showerhead has less time to dry out in more tropical climates, so bacteria can grow more easily.这很可能是因为在热带气候下，喷头没有足够的时间完全干燥，所以细菌更容易繁殖。Even if becoming ill from your showerhead is highly unlikely, you'd probably still like to reduce the number of bacteria coming out when you're trying to get clean.即使因淋浴喷头而生病的可能性极低，你在洗澡时大概仍然希望减少从喷头喷出的细菌数量。One study found that the spray pattern of your shower makes a difference – mist mode spreads NTM cells a lot more than a massage or rain showerhead, for example.有研究发现，喷头的喷水模式也会影响细菌扩散。例如，雾状喷洒模式比按摩式或雨淋式喷头传播更多 NTM 细胞。Higher temperatures have also been shown to spread microbes more easily. The best way to keep bacteria away though is to regularly clean your showerhead by descaling it or soaking it in lemon juice.研究还表明，高温会更加促进微生物扩散。而减少细菌的最佳方法是定期清洁喷头，例如除水垢或浸泡在柠檬汁中。Since we can't fully eradicate the microbes in our showers, and we like to stay clean, we'll have to learn to coexist with them.既然我们无法彻底消灭淋浴中的微生物，而我们又喜欢保持清洁，那么我们只能学会与它们共存。