The term nanotechnology was coined as far back as 1974 by Prof. Norio Taniguchi to describe emerging ways of manipulating materials at the atomic level [1]. A few decades later, nanotechnology encompasses pretty much any technique, material, or device that is fabricated or operated at the nanoscale (where a nanometer is a billionth of a meter). Recent advances have been made in nanomaterials (ultra-thin or ultra-strong materials that suit various engineering purposes), nanoparticles (tiny particles that can be used to enhance drug delivery or medical imaging), and nanoscale robots (such as the organic xenobots recently designed for medical use [2]).

So, what are the parameters of these new technologies? What are the dangers? And what are the proposed benefits? As with any endeavor, there is a certain balancing act between foreseeable risk and gain, though some risks are far more likely than others.

Nanomaterials are fabricated at the nanoscale to have particular properties, such as size, strength, or the way they interact with light. You could create ultra-tough armor by arranging the atoms in a particular way or build tiny robots that are capable of responding to simple instructions.

Multiwalled carbon nanotubes are strong and stiff structures that are formed on the nanoscale. They have useful electrical properties and are used in manufacturing, although there are growing concerns that exposure to these nanotubes leads to lung damage [3, 4, 5]. This serves as a reminder that caution is needed when dealing with new materials, particularly with regards to their effect on health and the environment, with various task forces in place to assess potential risks [6, 7].

Silver nanoparticles are currently used in clothes and medical dressings, though more research is needed to assess the effect of silver nanoparticles collecting on the skin [8].  Sunscreens containing nanoparticles that enhance their performance have also been the subject of public concern, though many studies have shown that these particles are not absorbed deep into the skin and therefore pose a low health risk [9, 10]. One unanswered question is the environmental impact of nanoparticles and nanomaterials that make their way into the ecosystem, with concerns about groundwater and soil contamination [11].

An interesting emerging point is that while in some countries (predominantly in Asia), nanotechnology is often viewed as a positive and benign technology, with products containing nanoparticles considered to be superior and priced accordingly, in other parts of the world, nanotechnology is generally treated with more suspicion. This led manufacturers in the west to unnecessarily reduce the concentration of nanoparticles in sunscreen to allay public concerns [12], despite repeated tests indicating their safety.

Another key branch of nanotechnology is the development of nanoscale machines, or nanobots, for surgery and drug delivery, though they were initially proposed for use in manufacturing. In his 1986 book Engines of Creation, nanotech pioneer Eric Drexler used the term “grey goo” to describe a nightmarish scenario in which self-replicating nanobots originally designed to build cheap goods run wild and consume the Earth [13]. This idea of a fast and unstoppable catastrophe was expanded and developed by others, quickly passing into the public imagination, where it has remained ever since [14]. Scientists, including Eric Drexler, who later said he wished he’d never mentioned grey goo [15], have tried to set the record straight about the extreme unlikelihood of nanobots escaping from a lab, stating that nanobots used in manufacturing do not need to be self-replicating [16]. Efforts to turn the tide of public opinion have been met with mixed results, possibly as the idea of the destructive potential of an advanced technology you cannot see with the naked eye nor control with your hands is too firmly cemented in popular culture and tabloid media [17].

Recent developments in nanobot design and applicability will likely reopen discussions of nanobot safety, with researchers presenting a novel approach to creating adjustable nanobots from organic sources [2]. Scientists developed a process for creating functional novel lifeforms, using artificial intelligence to automatically design a lifeform required to perform a particular function, and a construction toolkit to create a living organism using the candidate lifeform as a blueprint. The resulting nanobots, named xenobots, were constructed using cells from the African clawed frog, Xenopus laevis.

The advantages of this technology are clear: xenobots are biodegradable and could potentially be used in repairing damaged tissue, targeting cancer cells, cleaning up radioactive material, or collecting microplastics in the ocean. However, concerns have been raised about the ethical considerations related to creating what is essentially a new lifeform. As this technology is in its infancy, many more iterations will be required before we can assess its associated risks, with the xenobots creators acknowledging the need for a detailed ethical discussion. 

Magnetic nanobots have also been developed for use in targeted cancer treatment [18]. These can be loaded with anticancer drugs and guided through the body, offering a less invasive and more precise option to conventional drug delivery. These nanobots provide enhanced tumor reduction, possibly because they can deliver anticancer drugs deep and with great precision. This type of technique opens up the possibility of fast and effective treatment to those with hard-to-reach tumors. MRI can also be used to guide nanobots through human veins for improved drug delivery [19].

Nanotechnology now encompasses such a wide range of structures and techniques, used in such diverse fields, that it is increasingly difficult and unhelpful to oversimplify its advantages and disadvantages. Certain applications seem to present few downsides, whereas others that may have an environmental or health impact may require more caution, and many organizations worldwide focus on the ethical and safe development of nanotechnology [7, 14]. In the end, nanotechnology will most likely represent just another stage in our technological evolution, providing many distinct benefits that carry varying degrees of risk.