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Technologies based on nanoscale materials—for example, particles that are more than 10,000 times smaller than the period at the end of this sentence—play a growing role in our world.

Carbon nanofibers , silver nanoparticles , and moisturizing nanoparticles called nanoliposomes are .

Nanotechnology is also revolutionizing medicine and pushing the boundaries of human performance. If you received a COVID-19 vaccine in the United States, .

In the future, nanotechnology may allow doctors to better like cancer and dementia because nanoparticles pass easily through the blood-brain barrier.

may temporarily correct vision. And strategically implanted nanoparticles in the eyes, ears or brain may enable or hearing that's . Nanoparticles could even allow people to control their smart homes and cars .

This isn't science fiction. These are all active areas of research.

But frameworks for assessing the safety and ethics of nanoparticles have not kept pace with research. As working in bioscience, this limited oversight worries me. Without updated frameworks, it's hard to tell whether nanotechnology will make the world a better place.

Nano—what and why?

Any particle or material in one dimension can be classified as "nano." The period at the end of this sentence is 1,000,000 nanometers, and a human hair is about 100,000 nm in diameter. Both are much too large to be considered "nano." A single coronavirus is about 100 nanometers in diameter, and soot particles from forest fires can be —two examples of naturally occurring nanoparticles.

Nanoparticles can also be produced in a laboratory. The adenovirus vectors, nanolipoparticles and mRNA are engineered nanoparticles. The zinc oxide and titanium dioxide used in are also engineered nanoparticles, as is the .

Nanoparticles are useful because they have different properties than larger materials, even when they have . For example, large particles of zinc oxide can't be dissolved in water and are used as pigment in white paint.

Nanoscale zinc oxide is used in sunscreen, where it looks nearly transparent but reflects sunlight away from your skin to prevent sunburn.

Nanoscale zinc oxide also exhibits that could be useful for making antimicrobial surfaces, but the reason for its antimicrobial properties is not completely understood.

And therein lies the problem. While many scientists are interested in exploiting the positive properties of nanomaterials, my colleagues and I are concerned that scientists still .

Nanotechnology safety

Nanoparticles are attractive to biomedical researchers because they can . The antimicrobial properties of nanoscale zinc oxide are probably related to their ability to cross bacterial cell membranes. But these nanoparticles can as well.

In the United States, zinc oxide is "" by the Food and Drug Administration for products like sunscreen because it's unlikely—in sunscreen—to be toxic to humans.

However, although scientists understand the health effects of large particles of zinc oxide fairly well, they don't fully understand the health effects of nanoscale zinc oxide. Laboratory studies using human cells have produced conflicting results, .

I'm a big believer in sunscreen. But I also worry about the environmental effects of particles that are .

Hundreds of tons of nano-zinc oxide are produced each year, and it doesn't degrade easily. If we don't understand its behavior better, there's no way to predict whether it will eventually become a problem—though increasing evidence suggests nano-zinc oxide from sunscreen is .

Nanotechnology ethics

Nanoparticles' ability to cross cell membranes does make them effective in therapeutics like vaccines. Nanoparticles show promise for , and they could one day treat muscular dystrophy, or the natural atrophy that comes with age.

But COVID-19 vaccines provide a cautionary tale—nanoparticle-enabled COVID-19 vaccines were quickly adopted by the United States and Europe, but lower income countries had due to patent protections on the vaccine and a lack of production and storage infrastructure.

Nanoparticles may also allow for human performance enhancements, ranging from to soldiers engineered to be .

Without an ethical framework for their use, performance-enhancing nanotechnologies that are accessible only in certain places could deepen wealth gaps between high- and low-income countries.

Emerging oversight

Today, different countries treat nanoparticles differently. For example, the European Union's has banned the use of nanoscale zinc oxide in aerosol sunscreens across the E.U., citing their potential to get into lung cells and, from there, move to other parts of the body. The United States has not taken similar action.

The European Union has established a to study the health and environmental effects of nanoparticles.

In the United States, the , a coordinated government-sponsored research and development effort, is working to bring legal and ethical experts . They'll weigh the benefits and risks of nanotechnologies and disseminate information to other scientists and the public.

Overcoming the disparity in nanoparticle-enabled vaccine distribution is another issue altogether. The World Health Organization's COVAX program sought to ensure to COVID-related therapeutics. Similar measures should be considered for all nanotechnology-enabled medicine so everyone can benefit.

Synthetic biology is a field that is experiencing similarly rapid growth. For the past 20 years, the nonprofit has held an annual worldwide student competition, which it uses as a platform to teach young scientists to think about the broader implications of their work.

The iGEM Foundation requires participants to consider safety, security and whether their project is "." The nanotechnology research community would benefit greatly from adopting a similar model. Nanotechnologies that change the world for the better require coordinating science and ethics to shape how they are used and controlled long after we create them.

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