微小的材料，大问题：纳米技术的绿色如何？

This story originally appeared atEnsia。

在recent years, efforts to develop the Next Big Thing — whether in medicine, computer technology, pollution prevention or high-performance materials — have turned to some really, really small things: nanomaterials.

在纳米级工作（这可能意味着近乎原子的尺度），物质比蚂蚁的长度短一百万倍，比人的头发瘦一千倍 - 具有创建可以以否则的方式执行任务的新材料的能力可能是不可能的。

But it also brings new concerns and challenges related to understanding environmental and human health impacts, because at the nanoscale, substances often take on chemical, biological and physical properties they otherwise might not have and behave in ways they might not at conventional sizes.

简而言之

尽管定义有所不同，但纳米材料通常以约1至100纳米的长度，宽度，高度或直径为1至100亿分之一的时间。他们利用在这种微小的大小时表现出的物理，化学和其他特征物质。

At the nanoscale, materials can have different boiling points, magnetic properties and optical properties (color, fluorescence or透明度）。他们可以以不大尺寸的方式进行电力或渗透，并与活细胞和其他材料相互作用。

And simply because they are so small, nanomaterials are capable of moving in ways and to places — whether in the environment or the human body — larger compounds cannot. It’s because of these special properties that nanomaterials are being developed for so many applications.

不久前，科幻小说的主题（迈克尔·克里顿（Michael Crichton）"nanobots,"for example), nanomaterials can be found in a vast array of items. Some are being used to make extremely strong yet lightweight building materials, to efficiently store energy, to detoxify pollutants or to create antibacterial surfaces. Others are being used to deliver medical treatments to individual cells, to detect harmful bacteria or to create new ways of producing computer chips and半导体。

美国国家家禽研究中心的主要科学家博森公园说，美国农业部正在研究如何使用纳米技术检测病原体，并正在探索如何将纳米材料添加到可食用食品中。帕克说，使用纳米技术检测有害细菌，大大可以减少识别爆发来源所需的时间。

因为它们是如此的小，所以纳米材料能够以方式和地点（无论是在环境还是人体中）移动 - 较大的化合物不能。

在另一项应用中，加拿大的研究人员正在利用纳米颗粒清除高度持久的有毒碳氢化合物化合物的明显能力油砂废水。

更明显的是，这些特性中的某些特性正在利用袜子和内衣等服装中的气味，以阻止塑料食品容器和儿童填充动物中的微生物，并使防晒霜更容易在皮肤中消失。

The list of everyday and more specialized products in which nanomaterials are being used goes on: bicycles, cosmetics, personal care products and household appliances as well as electronics, aircraft and automotive parts, and pharmaceuticals.One database (PDF)has logged more than 400 consumer products that contain nanosilver used as an antibacterial agent — just one of many nanomaterials used in products on the market. Among these are toothpaste, pet and baby blankets, hair brushes and a vacuum cleaner.

"Nanotechnology is already pervasive. It’s not a research fantasy any more," said Lisa Friedersdorf, deputy director of the U.S.国家纳米技术协调办公室。

Small stuff, big questions

纳米技术通常被称为“新兴”技术，而我们完全了解其毒理学和环境影响也很远。但是，使纳米材料如此独特的相同特征也引发了有关其与环境，野生动植物，我们的粮食供应和人体的互动的严重问题。

作为加州大学圣塔芭芭拉分校社会纳米技术中心noted, "These new nanotechnologies pose many uncertainties for society. The risks that may accompany their use are largely unknown [and may be] difficult to anticipate."

一些研究表明sockstreated with nanosilver can release that silver when they’re washed. Others suggest that nanosilver can be released fromplastics，包括使用的食品容器。测试由食品安全中心has found nanoparticles of titanium dioxide in numerous food products, including cheese, chocolate, candy and mayonnaise.

A whitening agent, titanium dioxide, is approved for use in food at the conventional size. The U.S. Food and Drug Administration, the federal agency that approves food additives, said we don’t yet know enough about materials engineered at the nanoscale to use them without special approval.

Manufacturers of food in which the nanoscale titanium dioxide was found say these particles were not specially engineered or added but occurred unintentionally with those of conventional size. But because these particles are so small, there is concern they may behave in ways more toxic than their larger cousins. Right now European chemicals authorities are considering how to classify the carcinogenicity of titanium dioxide — including in its nano-form — a deliberation that could lead to its restriction in consumer products.

Some researchers are examining how ecosystems might be affected if nanosilver gets into soil and water sediment after products end up in the废物流。其他人发现植物可以吸收纳米层如果土壤中存在，则以微小的数量。作为美国环境保护局解释说在其网站上，评估纳米材料的毒性“很难，因为它们具有独特的化学特性，高反应性，并且不会溶解在液体中”，并且因为现有的测试“可能无法测试纳米材料的安全性”。

Researchers at the University of Minnesota Twin Cities and University of Wisconsin-Milwaukee working with the可持续纳米技术中心正在探索纳米材料是否影响基因表达。目的是了解“亚致死”暴露如何为以后的健康问题奠定基础。鉴于纳米材料能够穿透细胞，这似乎尤其重要。

帕克说：“关于毒性有很大的问题。”

还担心，鉴于它们的尺寸，纳米材料可以penetrate skin and cells以较大的材料不能。许多研究一直在关注这些效果由于职业接触，环境暴露和接触含有纳米材料的消费产品。最近的一项研究发现engineered carbon nanotubes in children’s lungs，显然存在于其他空气污染物的混合物中的颗粒。

These tiny tubular particles pose concerns because of their ability to penetrate lung tissue and cause respiratory problems. Other research has noted carbon nanotubes’与石棉纤维相似，研究人员正在研究这些纳米材料是否可以以相同的方式影响肺组织石棉does — causing scarring and inflammation that can lead to lung cancer, mesothelioma and asbestosis.

Risks: Unknown

Adding to the inherent challenge of understanding the life-cycle impacts of these products is that the proliferation of nanomaterials and products containing them appears to be outpacing any systematic cataloguing or labeling of these products. Put simply, we don’t know exactly where and how they’re being used.

That means that in addition to not fully understanding nanomaterials’ hazards, the risks of exposure are also not yet well understood.

"Until we understand what realistic environmental concentrations [of nanomaterials] are likely to be, we don’t really know what the impacts are,” said University of California, Santa Barbara, Bren School of Environmental Science & Management doctoral candidate Kendra Garner, who is studying ways of测量纳米材料的环境影响，包括开发一个将有助于这些估计的特殊统计模型。

加纳说：“这非常复杂。”“目前还没有真正的技术来测量环境中的纳米材料。”

Even if researchers are able to take samples, "by the time you get to the lab they may have changed because they are so reactive," Garner said. "It’s even harder to figure out where they come from."

在考虑纳米材料的潜在环境或健康影响时，国家纳米技术倡议副主任丽莎·弗里德斯多夫（Lisa Friedersdorf）表示，重要的是要了解“在很少的应用中，您在谈论单个纳米颗粒”。她解释说，相反，它们更常见于“系统的一部分”。

Until we understand what realistic environmental concentrations [of nanomaterials] are likely to be, we don’t really know what the impacts are.

尽管特定的纳米材料可能不会在成品消费产品中引起人们的关注，但在制造过程中，它可能仍然具有“工人含义”。在electronics, for example, "nanofeatures may be wires that are really tiny or transistors that have features that are at the nanoscale," she explained.

The same thing is true of super-hydrophobic coatings that are stain- or mud-resistant — materials that use compounds at the nanoscale to make a texture that creates the desired performance. There are, however, some applications in which individual nanoparticles perform the job — in medicine, for example, where they can be used to home in on individual cells whether as a diagnostic tool or a pharmaceutical.

但是，作为食品安全中心高级政策分析师Jaydee Hanson观察到，虽然特定的纳米材料可能不会在成品消费产品中引起人们的关注，但在制造过程中，它可能仍然具有“工人含义”。

知识差距符合监管的鸿沟

随着纳米材料的扩散持续，科学家试图处理其潜在的人类和环境健康影响，监管机构正面临着自己的挑战：如何管理不像现有化学物质政策设计的材料。

The European Union has required labeling for nanomaterials used as antibacterials and in cosmetics自2013年以来。在新的下"novel food"regulation, the EU also will require prior approval of engineered nanomaterials used in food and may require special labels if the food "is not recommended for certain vulnerable groups" such as infants, children or pregnant women.

另一方面，美国没有任何形式的标签要求来指定产品含有纳米材料。实际上，负责监督化学成分安全性（主要是EPA和美国食品药品监督管理局）的美国联邦机构将纳米材料视为任何其他新化学物质，都可以逐案，而不是将其挑剔以进行特殊审查由于它们的大小，任何形式。

Simply put, we don’t know enough about nanomaterials to know if standard health and safety measures will be effective.汉森说，这可能会带来问题，因为这意味着使用监管“工具来完成他们不一定要做的工作”。

For example, because nanoparticles are so small and behave so differently from larger particles, equipment that ordinarily would be used to clean up an indoor spill or protect workers from inhaling particles won’t necessarily work on them. Similarly, nanomaterials’ size means they can’t be treated as other environmental contaminants might be in terms of pollution prevention.

同时，关于化学品在产品中如何行为的假设不一定适用于纳米材料。目前，有"a growing concern about the lack of environmental health and safety data (PDF),"said the EPA.

简而言之，我们对纳米材料的了解不足以知道标准的健康和安全措施是否有效，或者我们是否正在向这些新材料提出正确的问题以确保安全使用。

Push for oversight

缺乏要求标签或其他材料上市的法规也意味着美国没有任何含有纳米材料的产品的官方清单。目前，最全面目录就产品类别而言，是由Project on Emerging Nanotechnologies，皮尤慈善信托基金会和伍德罗·威尔逊国际中心的联合计划。

最近推出了另一个包含纳米材料的产品的数据库食品安全中心and focuses on food and food-contact products. Some products listed in both inventories make explicit claims for their nanotechnology — such as carbon nanofiber materials in sports gear or nanosilver used as an antimicrobial agent in clothing or food containers — but others do not.

“这使消费者感到困惑。”威尔逊中心Science and Technology Innovation Program senior associate Todd Kuiken. And said Kuiken, it’s very possible that a company may not know the details of the nanotechnology used in its products because it may have purchased ingredients or other components for which full details of proprietary formulas or technology may not have been disclosed. This also adds to the difficulty in understanding these products’ potential environmental and health impacts.

环境和消费者的拥护者说，EPA对如何使用纳米材料的使用不足。

For example, the Center for Food Safety, Beyond Pesticides, Clean Production Action, Center for Environmental Health and other groups filed suit against the agency asking it to regulate all uses of nanosilver as it would a pesticide or another antimicrobial chemical. Under existing regulations, the EPA is responsible for granting approval of materials that make antibacterial claims.

因此，如果制造商明确表示其食品容器将“杀死细菌”或其织物处理将“破坏微生物”，则这些产品应由EPA注册并单独批准。但是，声称涉及诉讼的团体，在含有纳米砂剂的产品时，EPA未能充分执行这些法规，允许未经EPA批准出售含有纳米层的产品（但不提出特定的杀菌索赔）。

公司很可能不知道其产品中使用的纳米技术的细节。

美国消费产品安全委员会一直在仔细研究一些含有纳米材料的消费产品。Back in 2008, these groups filed a legal petition with the EPA asking it to take such action. Six years later, the EPA had failed to respond — so in December 2014, the groups filed suit against the EPA both for the EPA’s failure to respond to their petition and to again ask the EPA to fully regulate nanosilver as a pesticide.

在三月（PDF）the EPA agreed that nanosilver products sold with the intent of killing microorganisms do qualify as pesticides. But it refused the groups’ request to automatically consider all nanosilver products as pesticides — including those that don’t make explicit germ- or bacteria-killing claims.

然而，与此同时，自2011年以来，作为国家纳米技术倡议的一部分 -资金为16亿美元in the 2016 federal budget — the U.S. Consumer Product Safety Commission has been taking a hard look at some consumer products containing nanomaterials.

With other federal agencies, including the EPA, FDA and National Institute for Occupational Safety and Health, the CPSC has been working to develop ways of assessing the potential airborne release of nanoparticles from various consumer products — among them aerosol sprays, sports equipment and products that might pose special exposures to children.

And while there doesn’t appear to be any federal move afoot to require labeling of nanomaterials in products sold in the U.S., the Environmental Working Group has launched an initiative involving personal care products and cosmetics asking manufacturers to add product toxicity details to the information visible to consumers either in stores, on packages or online.

在该计划中持续一年的公司还将被要求以符合欧盟要求的方式披露标签上的成分，其中包括披露使用纳米材料。希望这将有助于对其他公司效仿的消费者需求。这种成分披露的压力已导致国家通过化学报告和GMO标签法。

EWG研究副总监Nneka Leiba说：“我们称其为'移动市场。”

食品安全性汉森（Hanson）表示，一直在推动EPA进行更严格监督纳米砂产品的团体也在推动该机构对其他纳米材料的审查，其中包括用于塑料中的纳米硅酸盐化合物。

底线

那么，纳米技术对人类健康和环境的影响的底线是什么？

本质上，我们还不知道。一方面，纳米技术应用提供了许多有前途的解决方案，无论是在污染，医学，水处理，电子和能源生产还是无数其他领域。另一方面，许多科学都在提出这些材料呈现潜在的环境和健康危害。目前，纳米材料还没有被完全分类，监测或调节，这只会增加理解其环境影响的挑战。

在other words, the application of very, very small technologies still carries some very, very big questions about where these materials are being used, how they are behaving and what we need to do to protect ourselves and the rest of the planet against unwanted impacts and exposures.