研究人员在瓶装水中检测到大量塑料颗粒

微小的塑料碎片无处不在。 现在，研究人员发现它们在瓶装水中的浓度比之前估计的高出 10 ～100 倍。

哥伦比亚大学和罗格斯大学的研究人员在一升典型瓶装水中发现了大约 240,000 个可检测到的塑料碎片。 该研究于周一发表在《美国国家科学院院刊》。

检测到的塑料颗粒中约10%是微塑料，其余90%是纳米塑料。 微塑料的尺寸在5毫米到1微米之间； 纳米塑料是尺寸小于1微米的颗粒。 作为对比，人类头发约为 70 微米粗。

研究已经发现微塑料存在于人类的肺、排泄物、血液、和胎盘等地方。 2018 年的一项研究发现，每升瓶装水中平均含有 325 颗微塑料。

纳米塑料可能比微塑料更危险，因为当进入人体时，“它越小，就越容易被误认为是细胞的天然成分，”哥伦比亚大学化学教授魏敏（Wei Min）说。 他是该研究论文的共同作者。

研究人员使用一种名为受激拉曼散射（SRS）显微镜来检测这些粒子，并用机器学习来识别它们。这种技术涉及两种激光。 他们使用该系统搜索了七种常见的塑料：聚酰胺 66、聚丙烯、聚乙烯、聚甲基丙烯酸甲酯、聚氯乙烯、聚苯乙烯、和聚对苯二甲酸乙二醇酯。

他们测试了三个品牌的瓶装水； 但是没有透露其名称。

哥伦比亚大学拉蒙特-多尔蒂地球观测站的研究教授严北战（Beizhan Yan）说，他们能够识别的颗粒仅占他们发现的总颗粒的 10%，其余的可能是矿物质、其他类型的塑料、或其他东西。 他是该研究的共同作者。

代表美国和国际水装瓶商和分销商的行业组织国际瓶装水协会在一份声明中表示，该协会只得到 “非常有限的通知和时间” 来审查这项研究。

但该组织表示，新的检测方法“需要得到科学界的全面审查，并且需要进行更多的研究来开发测量和量化我们环境中纳米塑料的标准化方法。”

该协会表示，“对于纳米和微塑料颗粒对健康的潜在影响，科学界尚未达成共识”。 它补充说：“媒体关于饮用水中这些颗粒的报道只不过是不必要地吓唬消费者。”

研究人员推测，瓶装水中的一些塑料可能是从水过滤器中使用的塑料中脱落的。

另一位研究合著者、罗格斯大学药理学和毒理学教授菲比·斯塔普尔顿 (Phoebe Stapleton) 表示，研究人员已经知道纳米塑料存在于水中。 “但如果你无法量化它们或无法将它们视觉化，就很难相信它们确实存在，”她说。

斯特普尔顿说，他们小组研究的意义在于，它现在“揭示了这一点，不仅提供了计算机生成的图像，而且还允许量化，更重要的是，这种量化的化学原理”。

他们希望这项研究能够帮助人们更好地了解人类经常摄入多少塑料及其影响。

严博士说，他们计划在未来的研究中采用相同的技术来观察自来水、空气、食物、和人体组织中的塑料颗粒。 “这基本上只是为我们打开一扇新的窗户，让我们看到这个看不见的世界[究竟是什么]。”

据联合国称，人类每年生产超过 4.4 亿吨塑料。 研究人员表示，大约 80% 的塑料最终进入垃圾填埋场或环境中。

Researchers find a massive number of plastic particles in bottled water

https://www.npr.org/2024/01/10/1223730333/bottled-water-plastic-microplastic-nanoplastic-study

Microscopic pieces of plastic are everywhere. Now, they've been found in bottled water in concentrations 10 to 100 times more than previously estimated.

Researchers from Columbia University and Rutgers University found roughly 240,000 detectable plastic fragments in a typical liter of bottled water. The study was published Monday in the Proceedings of the National Academy of Sciences.

About 10% of the detected plastic particles were microplastics, and the other 90% were nanoplastics. Microplastics are between 5 millimeters to 1 micrometer; nanoplastics are particles less than 1 micrometer in size. For context, a human hair is about 70 micrometers thick.

Microplastics have already been found in people's lungs, their excrement, their blood and in placentas, among other places. A 2018 study found an average of 325 pieces of microplastics in a liter of bottled water.

Nanoplastics could be even more dangerous than microplastics because when inside the human body, "the smaller it goes, the easier for it to be misidentified as the natural component of the cell," says Wei Min, a professor of chemistry at Columbia University and one of the study's co-authors.

The researchers used a technology involving two lasers called stimulated Raman scattering (SRS) microscopy to detect the particles and used machine learning to identify them. They searched for seven common types of plastic using this system: polyamide 66, polypropylene, polyethylene, polymethyl methacrylate, polyvinyl chloride, polystyrene and polyethylene terephthalate.

They tested three brands of bottled water; they did not identify the brands.

The particles they could identify accounted for only 10% of total particles they found — the rest could be minerals, or other types of plastics, or something else, says Beizhan Yan, a research professor at the Lamont-Doherty Earth Observatory of Columbia University and a co-author on the study.

The International Bottled Water Association, an industry group that represents U.S. and international water bottlers and distributors, said in a statement that it has had "very limited notice and time" to review the study. 

But the group said the new detection method "needs to be fully reviewed by the scientific community and more research needs to be done to develop standardized methods for measuring and quantifying nanoplastics in our environment."

The association said there is "no scientific consensus on the potential health impacts of nano- and microplastic particles." It added: "media reports about these particles in drinking water do nothing more than unnecessarily scare consumers." 

The researchers hypothesize that some of the plastics in the bottled water could be shedding from, ironically enough, the plastic used in types of water filters.

Phoebe Stapleton, another study co-author who is a professor of pharmacology and toxicology at Rutgers University, says researchers have known that nanoplastics were in water. "But if you can't quantify them or can't make a visual of them, it's hard to believe that they're actually there," she says.

The significance of their group's research is that it now "brings that to light, and not only provides what is a computer generated image, but it also allows for the quantification and even more importantly, the chemistry of that quantification," Stapleton says.

They hope the research will lead to having a better understanding of how much plastic humans are regularly putting into their bodies and its effects.

Yan says they plan future research employing the same technology to look at plastic particles in tap water, in the air, in food and in human tissues. "This is basically just to open a new window for us to see [what was] this invisible world before."

Humans produce more than 440 million tons of plastic each year, according to the United Nations. About 80% of plastic ends up in landfills or the environment, researchers say.