Study Finds Small Plastic Pieces in Bottled Water

Study Finds Small Plastic Pieces in Bottled Water

研究发现瓶装水中含有微小塑料颗粒

【听力音频】

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　　By John Russell

　　17 January 2024

　　The average liter of bottled water has nearly a quarter million invisible pieces of very small plastic known as nanoplastics, a recent study says.

　　Researchers found the nanoplastics with a microscope using dual lasers.

　　Scientists long figured there were lots of these very small plastic pieces. But until researchers at Columbia and Rutgers universities did their calculations, they never knew how many or what kind.

　　Looking at five samples each of three common bottled water brands, researchers found particle levels ranged from 110,000 to 400,000 per liter. The average was around 240,000, the study said. The research appeared recently in the publication Proceedings of the National Academy of Sciences.

　　Nanoparticles are particles that are less than a micron in size. In comparison, a human hair is about 83 microns wide.

　　Previous studies have looked at slightly bigger microplastics that range from 5 millimeters, which could be seen by human eyes, to one micron. About 10 to 100 times more nanoplastics than microplastics were discovered in bottled water, the study found.

　　Much of the plastic seems to be coming from the bottle and the filtration system to clean the water itself, said the study's lead writer Naixin Qian of Columbia University.

　　She would not name the three brands because researchers want more samples and they want to study more brands. Still, she said they were common and bought at a Walmart, a popular store in the U.S.

　　Researchers still cannot answer the big question: Are those nanoplastic pieces harmful to health?

　　"That's currently under review. We don't know if it's dangerous or how dangerous," said study co-writer Phoebe Stapleton of Rutgers University. "We do know that they are getting into the tissues (of mammals, including people) ... and the current research is looking at what they're doing in the cells."

　　The International Bottled Water Association said in a statement: "There currently is both a lack of standardized (measuring) methods and no scientific" agreement on the possible health effects of nano- and microplastic particles. The statement added, "Therefore, media reports about these particles in drinking water do nothing more than unnecessarily scare consumers."

　　The American Chemistry Council, which represents plastics manufacturers, declined to immediately comment.

　　The Associated Press spoke with four co-writers of the study. All of them said they would cut back on their bottled water use.

　　Columbia chemist Wei Min said he has reduced his bottled water use by half. Stapleton said she now depends more on filtered water at home in New Jersey.

　　But study co-author Beizhan Yan, a Columbia environmental chemist who increased his tap water usage, pointed out that filters themselves can be a problem by introducing plastics.

　　"There's just no win," Stapleton said.

　　Outside experts, who praised the study, agreed that there is a general unease about the risks of fine plastic particles. Still, it is too early to say anything certain about the risks.

　　"The danger of the plastics themselves is still an unanswered question. For me, the additives are the most concerning," said Jason Somarelli of Duke University in North Carolina. Somarelli was not part of the research. He added, "We and others have shown that these nanoplastics can be internalized into cells, and we know that nanoplastics carry all kinds of chemical additives that could cause cell stress, DNA damage and change metabolism or cell function."

　　Somarelli said his own research has found more than 100 "known cancer-causing chemicals in these plastics."

　　Dual laser microscope

　　About 15 years ago, Min invented dual laser microscope technology that identifies specific compounds by their chemical properties and how they respond when exposed to lasers. Yan and Qian talked to him about using that technique to find and identify plastics that had been too small for researchers using established methods.

　　Kara Lavender Law of the Sea Education Association said "the work can be an important advance in the detection of nanoplastics," but she said she'd like to see other chemists use the technique and get the same results.

　　Yan said he is starting to study water supplies in the U.S. cities of Boston, St. Louis, Los Angeles and elsewhere to see how much plastics are in their tap water. Previous studies looking for microplastics and some early tests suggest there may be less nanoplastic in tap water than in bottled water.

　　Even with unknowns about human health, Yan said he does have one suggestion: Use reusable bottles instead of single-use plastics.

　　I'm John Russell.

　　And I'm Ashley Thompson.

　　Seth Borenstein reported on this story for the Associated Press. John Russell adapted it for VOA Learning English.

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　　作者：约翰·罗素

　　2024年1月17日

　　最近的一项研究表明，平均每升瓶装水中都含有近25万个看不见的微小塑料颗粒，这些被称为纳米塑料。

　　研究人员使用双激光显微镜发现了这些纳米塑料。

　　科学家们早就认为存在大量的这种微小塑料颗粒。但是，直到哥伦比亚大学和罗格斯大学的研究人员进行了他们的计算，他们才知道这些塑料颗粒的数量和种类。

　　研究人员对三种常见瓶装水品牌各取五个样本进行研究，发现每升水中的微塑料颗粒数量范围在11万到40万之间。研究表明，平均值约为24万。这项研究最近发表在《国家科学院院刊》上。

　　纳米颗粒是指大小小于一微米的颗粒。相比之下，人的头发宽度约为83微米。

　　以前的研究已经研究过稍大一些的微塑料，其大小范围从5毫米（肉眼可见）到一微米。研究发现，瓶装水中的纳米塑料数量比微塑料多10到100倍。

　　研究的主要作者、哥伦比亚大学的钱乃鑫表示，大部分塑料似乎来自瓶子本身和用于净化水的过滤系统。

　　她没有透露这三个品牌的名称，因为研究人员希望获取更多的样本，并希望研究更多的品牌。然而，她表示这些品牌都很常见，都是在美国一家受欢迎的商店沃尔玛购买的。

　　研究人员仍然无法回答一个重大问题：这些纳米塑料颗粒对健康有害吗？

　　"这个问题目前正在审查中。我们不知道它是否危险，或者有多危险，"罗格斯大学的研究合作者菲比·斯泰普尔顿说。"我们确实知道它们正在进入（包括人类在内的哺乳动物的）组织...目前的研究正在研究它们在细胞中做了什么。"

　　国际瓶装水协会在一份声明中说："目前缺乏标准化的（测量）方法，也没有科学"对纳米和微塑料颗粒可能的健康影响的一致意见。声明还补充说，"因此，关于饮用水中这些颗粒的媒体报道只会无谓地吓唬消费者。"

　　代表塑料制造商的美国化学理事会拒绝立即发表评论。

　　美联社采访了这项研究的四位合著者。他们都表示，他们会减少瓶装水的使用。

　　哥伦比亚大学的化学家魏敏说，他已经将瓶装水的使用量减少了一半。斯泰普尔顿说，她现在更依赖新泽西家中的过滤水。

　　但是，研究的合著者、哥伦比亚大学的环境化学家严北展增加了自来水的使用，他指出过滤器本身可能会引入塑料，这是一个问题。

　　"没有绝对的胜利，"斯泰普尔顿说。

　　外部专家对这项研究给予了赞扬，他们认同存在对微塑料颗粒风险的普遍不安。然而，关于风险的确切情况，现在还为时过早。

　　"塑料本身的危险性仍是一个未解的问题。对我来说，最令人担忧的是添加剂，"北卡罗来纳州杜克大学的杰森·索马雷利说。索马雷利并未参与这项研究。他补充说，"我们和其他人已经证明，这些纳米塑料可以被细胞内化，我们知道纳米塑料携带了各种可能导致细胞应激、DNA损伤和改变代谢或细胞功能的化学添加剂。"

　　索马雷利说，他自己的研究发现这些塑料中含有100多种"已知的致癌化学物质"。

　　双激光显微镜

　　大约15年前，魏敏发明了一种双激光显微镜技术，该技术通过化学性质和激光照射时的反应来识别特定的化合物。严北展和钱乃鑫与他讨论了如何使用这种技术来寻找和识别使用已有方法的研究人员无法识别的过小的塑料。

　　海洋教育协会的卡拉·薰衣草·劳说，"这项工作可能是检测纳米塑料的重要进步，"但她表示，她希望看到其他化学家使用这种技术并得到相同的结果。

　　严北展说，他正在开始研究美国波士顿、圣路易斯、洛杉矶等城市的水供应，以查看他们的自来水中有多少塑料。寻找微塑料的先前研究和一些早期测试表明，自来水中的纳米塑料可能比瓶装水中的少。

　　即使关于人类健康的未知因素，严北展说他有一个建议：使用可重复使用的瓶子，而不是一次性塑料。

　　我是约翰·罗素。

　　我是阿什利·汤普森。

　　塞思·博伦斯坦为美联社报道了这个故事。约翰·罗素为美国之音学习英语改编了它。

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　　故事中的词汇

　　sample – n. 从某物中取出的一部分，用于获取关于该物的信息

　　brand - n. 由特定公司生产的所有产品的类别

　　review - v. 在做决定或判断之前仔细查看或检查（某物）

　　standardize – v. 改变（事物）使其相似且一致

　　tap water – n. 通过公共水系统的管道流出的水

　　internalize - v. 吸收或接纳

　　metabolism - n. 植物或动物利用食物或水产生能量的化学过程

　　detect - v. 发现或注意到某物的存在