Bottled Water Can Contain Hundreds of Thousands of Tiny Plastic Bits瓶裝水或含數(shù)十萬塑料微粒

In recent years， there has been rising concern that tiny particles known as microplastics are showing up basically everywhere on Earth， from polar ice to soil， drinking water and food. Formed when plastics break down into progressively smaller bits， these particles are being consumed by humans and other creatures， with unknown potential health and ecosystem effects. One big focus of research： bottled water， which has been shown to contain tens of thousands of identifiable fragments in each container.

近些年，微塑料逐漸引起人們的擔憂——從極地冰川到土壤、飲用水和食物，這種微粒在地球上幾乎無處不在。微塑料是塑料在逐步分解的過程中形成的小顆粒，能被人和其他生物攝入，對人體健康和生態(tài)系統(tǒng)有何潛在影響尚不清楚。相關研究的一大焦點是瓶裝水，已發(fā)現(xiàn)每瓶水中含有數(shù)萬個可辨別的塑料碎片。

Now， using newly refined technology， researchers have entered a whole new plastic world： the poorly known realm of nanoplastics， the spawn1 of microplastics that have broken down even further. For the first time， they counted and identified these minute particles in bottled water. They found that on average， a liter contained some 240，000 detectable plastic fragments—10 to 100 times greater than previous estimates， which were based mainly on larger sizes.

如今，借助改進的技術，研究人員得以涉足鮮為人知的塑料新世界：納米塑料領域。納米塑料是微塑料進一步分解的產(chǎn)物。研究人員首次對瓶裝水中的這種極小微粒進行了辨別和計數(shù)。他們發(fā)現(xiàn)，平均每升瓶裝水中可檢測出的塑料碎片約24萬個，是以往主要基于較大尺寸顆粒的估值的10倍到100倍。

The study was published in the journal Proceedings of the National Academy of Sciences.

相關研究成果已發(fā)表在美國的《國家科學院院刊》上。

Nanoplastics are so tiny that， unlike microplastics， they can pass through intestines and lungs directly into the bloodstream and travel from there to organs including the heart and brain. They can invade individual cells， and cross through the placenta to the bodies of unborn babies. Medical scientists are racing to study the possible effects on a wide variety of biological systems.

與微塑料不同，納米塑料小到足以穿過腸道和肺部直接進入血液，然后隨血液抵達心臟和大腦等器官。它們甚至能侵入單個細胞，經(jīng)由胎盤進入胎兒體內(nèi)。醫(yī)學家們正在加緊研究納米塑料可能對各種生物系統(tǒng)造成的影響。

“Previously this was just a dark area， uncharted. Toxicity studies were just guessing what’s in there，” said study coauthor Beizhan Yan， an environmental chemist at Columbia University’s Lamont-Doherty Earth Observ-atory. “This opens a window where we can look into a world that was not exposed to us before.”

“以前，納米塑料領域是一個盲區(qū)。毒性研究也只能猜測里面有什么。”研究論文合著者顏備戰(zhàn)表示，他是哥倫比亞大學拉蒙特-多爾蒂地球觀測所的環(huán)境化學家，“現(xiàn)在，這項研究打開了一扇窗，透過它我們能一窺未曾探索過的世界?！?/p>

Worldwide plastic production is approaching 400 million metric tons a year. More than 30 million tons are dumped yearly in water or on land， and many products made with plastics including synthetic textiles shed particles while still in use. Unlike natural organic matter， most plastics do not break down into relatively benign2 substances; they simply divide and redivide into smaller and smaller particles of the same chemical composition. Beyond single molecules， there is no theoretical limit to how small they can get.

目前，塑料的全球年產(chǎn)量直逼4億噸。每年超過3000萬噸塑料被傾倒入水或被丟棄在陸地上，而且許多塑料制品，比如合成織物，在使用過程中也會釋放塑料顆粒。不同于天然有機物，大多數(shù)塑料不能分解為相對無害的物質(zhì)，而僅僅是不斷分解為越來越小但化學成分保持不變的顆粒。理論上講，塑料顆?？梢詿o限分解，直至小到單分子水平。

Microplastics are defined as fragments ranging from 5 millimeters down to 1 micrometer， which is 1 millionth of a meter. （A human hair is about 70 micrometers across.） Nanoplastics， which are particles below 1 micrometer， are measured in billionths of a meter.

微塑料是指直徑介于1微米（即百萬分之一米）和5毫米之間的塑料碎片。（一根人類頭發(fā)的直徑約為70微米。）納米塑料是直徑小于1微米的顆粒，以十億分之一米為計量單位。

Plastics in bottled water became a public issue largely after a 2018 study detected an average of 325 particles per liter; later studies multiplied that number many times over. Scientists suspected there were even more than they had yet counted， but good estimates stopped at sizes below 1 micrometer—the boundary of the nano world.

瓶裝水里的塑料之所以成為公共議題，在很大程度上是因為2018年的一項研究。該研究發(fā)現(xiàn)平均每升瓶裝水中含有325個塑料顆?！髞淼难芯繉⒃摂?shù)字翻了數(shù)番。科學家們認為實際數(shù)量甚至可能超過現(xiàn)有檢出量，可一旦跨過1微米這條界線下至納米領域，就難以獲得可靠的估值。

“People developed methods to see nano particles， but they didn’t know what they were looking at，” said the new study’s lead author， Naixin Qian， a Columbia graduate student in chemistry. She noted that previous studies could provide bulk3 estimates of nano mass， but for the most part could not count individual particles， nor identify which were plastics or something else.

“人們開發(fā)了不同方法來觀察納米顆粒，但又不清楚自己看到的是什么。”這項新研究的第一作者錢乃馨說道，她是哥倫比亞大學化學專業(yè)的研究生。她指出，此前的研究只能批量估算納米顆粒，多數(shù)情況下既無法計數(shù)單個顆粒，也無法辨別出是塑料還是其他物質(zhì)。

The new study uses a technique called stimulated Raman scattering microscopy， which was co-invented by study coauthor Wei Min， a Columbia biophysicist. This involves probing samples with two simultaneous lasers that are tuned to make specific molecules resonate. Targeting seven common plastics， the researchers created a data-driven algorithm to interpret the results. “It is one thing to detect， but another to know what you are detecting，” said Min.

這項新研究采用了受激拉曼散射顯微技術，該技術由研究論文的合著者、哥倫比亞大學生物物理學家閔瑋共同研發(fā)。受激拉曼散射顯微技術通過同時發(fā)射兩束激光對樣本進行探測，而這兩束激光已經(jīng)過調(diào)制，可使特定的分子產(chǎn)生共振。研究人員還針對7類常見塑料開發(fā)了一套數(shù)據(jù)驅(qū)動的算法，用于分析結果。對此，閔瑋說道：“檢測是一回事，知道檢測到的是什么則是另一回事。”

The researchers tested three popular brands of bottled water sold in the United States （they declined to name which ones）， analyzing plastic particles down to just 100 nanometers in size. They spotted 110，000 to 370，000 particles in each liter， 90% of which were nanoplastics; the rest were microplastics. They also determined which of the seven specific plastics they were， and charted their shapes—qualities that could be valuable in biomedical research.

研究人員檢測了在美國市場暢銷的3個瓶裝水品牌（未透露具體名稱），對水中直徑低至100納米的塑料顆粒進行了分析。他們發(fā)現(xiàn)每升水中包含11萬至37萬個塑料顆粒，其中90%是納米塑料，剩余的是微塑料。他們還測定了這些塑料顆粒屬于前述7類塑料中的哪一類，并繪制出了它們的形態(tài)特征——這可能對生物醫(yī)學研究具有重要價值。

One common one was polyethylene terephthalate or PET. This was not surprising， since that is what many water bottles are made of. （It is also used for bottled sodas， sports drinks and products such as ketchup and mayonnaise.） It probably gets into the water as bits slough off when the bottle is squeezed or gets exposed to heat. One study suggests that many particles enter the water when you repeatedly open or close the cap， and tiny bits abrade4.

其中，常見的一類塑料顆粒是聚對苯二甲酸乙二醇酯（或稱PET）。檢測出這類塑料并不奇怪，因為許多水瓶就是由PET制成的。（PET也用于瓶裝碳酸飲料、運動飲料以及番茄醬和蛋黃醬等產(chǎn)品的瓶體。）瓶體受擠壓或受熱時，PET可能會剝落形成小塑料片混入水中。一項研究表明，反復擰開擰上瓶蓋，小塑料片都會受到摩擦，從而使許多微粒進入水中。

However， PET was outnumbered by polyamide， a type of nylon. Ironically， said Beizhan Yan， that probably comes from plastic filters used to supposedly purify the water before it is bottled. Other common plastics the researchers found： polystyrene， polyvinyl chloride and polymethyl methacrylate， all used in various industrial processes.

然而，樣本中聚酰胺（尼龍的一種）顆粒的數(shù)量卻超過了PET。顏備戰(zhàn)表示，諷刺的是，聚酰胺顆粒很可能來自塑料材質(zhì)的過濾器，而它們本來的作用是在裝瓶前對水進行凈化。研究人員發(fā)現(xiàn)的其他常見塑料包括聚苯乙烯、聚氯乙烯和聚甲基丙烯酸甲酯，它們都用于各種工業(yè)生產(chǎn)過程。

A somewhat disturbing thought： the seven plastic types the researchers searched for accounted for only about 10% of all the nanoparticles they found in samples; they have no idea what the rest are. If they are all nanoplastics， that means they could number in the tens of millions per liter. But they could be almost anything， “indicating the complicated particle composition inside the seemingly simple water sample，” the authors write. “The common existence of natural organic matter certainly requires prudent distinguishment.”

令人有些不安的是，研究人員檢測的這7類塑料僅占樣本中發(fā)現(xiàn)的納米顆?？偭康?0%左右，而其余顆粒的成分還不得而知。倘若全是納米塑料，則意味著每升瓶裝水中的納米塑料可能多達數(shù)千萬個。然而，它們幾乎也可能是其他任何物質(zhì)?！斑@表明看似純凈的水樣中存在復雜的顆粒成分?！闭撐淖髡邆儗懙?，“由于天然有機物分布廣泛，必然要求謹慎的鑒別。”

The researchers are now reaching beyond bottled water. “There is a huge world of nanoplastics to be studied，” said Min. He noted that by mass， nanoplastics comprise far less than microplastics， but “it’s not size that matters. It’s the numbers， because the smaller things are， the more easily they can get inside us.”

研究人員正將研究范圍延伸到瓶裝水以外?！凹{米塑料領域還有廣闊的研究空間?！遍h瑋說道。他指出，就大小而言，納米塑料遠小于微塑料，但“關鍵不在于大小，而在于數(shù)量。因為顆粒越小，就越容易進入我們體內(nèi)”。

Among other things， the team plans to look at tap water， which also has been shown to contain microplastics， though far less than bottled water. Beizhan Yan is running a project to study microplastics and nanoplastics that end up in wastewater when people do laundry—by his count so far， millions per 10-pound load， coming off synthetic materials that comprise many items. （He and colleagues are designing filters to reduce the pollution from commercial and residential washing machines.） They also are collaborating with environmental health experts to measure nanoplastics in various human tissues and examine their developmental and neurologic effects.

此外，該團隊還計劃研究自來水——自來水中也檢測出了微塑料，盡管含量遠低于瓶裝水。顏備戰(zhàn)正在開展一項課題，研究洗衣過程中排入廢水的微塑料和納米塑料。目前的結果顯示，每洗滌10磅衣物就可釋放數(shù)百萬塑料顆粒，它們源于許多衣物所用的合成材料。（顏備戰(zhàn)和同事們正在設計過濾裝置以減少來自商用和家用洗衣機的污染。）該團隊也在與環(huán)境健康專家合作，檢測不同人體組織中的納米塑料，并調(diào)查它們對發(fā)育和神經(jīng)系統(tǒng)的影響。

“It is not totally unexpected to find so much of this stuff，” said Qian. “The idea is that the smaller things get， the more of them there are.”

“發(fā)現(xiàn)如此多的塑料顆粒并不完全出乎意料?！卞X乃馨說道，“問題在于，尺寸越小，數(shù)量就越多?！?/p>

（譯者為“《英語世界》杯”翻譯大賽獲獎者）

1 spawn產(chǎn)物。

2 benign無害的。" 3 bulk大量的，大批的；總的，整批的。

4 abrade磨損。