Also see Introduction to the Health Effects of Nanoparticles by Steve Gilbert.

Topic editor: Steven G. Gilbert
Lead author: Lester Jacobson

A Cobalt nanoparticle coated with layers of graphene (Wikicommons)


What are Nanoparticles?

The defining characteristic of nanoparticles is their size, which is 100 nanometers or less, which is roughly 70 times smaller than a red blood cell. Such small sizes is difficult to grasp, but a graphic at the website cellsalive helps give perspective about how to think about nanoparticles.


Nanoparticles have a long history of human use, dating as far back as 9th century Mesopotamia, where gold and copper nanoparticles were used to add luster and 'glitter' to pottery. But it is only recently that nanotechnology has been put into widespread, industrial use. Growing from a theoretical field to a large and well-funded industry, nanoparticles are now found in a huge variety of household items. The spread of nanotechnology was accompanied concerns about the health effects of nanoparticles.

A list of many of the nanoparticles on the market today can be found at

Government Policy

Though there is little regulation of nanotechnology in the United States, and most existing regulation is ineffective at protecting consumers from potentially dangerous nanoparticles. For example, manufacturers of carbon nano-tubes are required to meet workplace safety rules when they perform laboratory testing. But the results of these tests are treated as a business secret. Products are not required to say if they use nanotechnology.

The Environmental Protection Agency and the Food and Drug Administration, two government agencies which have the mandate to regulate nanotechnology, have only recently made the first, long-overdue step towards regulation. On June 9, 2011, the EPA launched voluntary program where nanotechnology companies can register their products. But it is uncertain where substantial regulation of nanotechnology is on the horizon in the US.

The European Union has taken a more aggressive approach to regulation. In 2007, the EU required nanoparticles to be labeled on the ingredients list of cosmetics, and required increased safety testing for cosmetics containing nanoparticles. Nanoparticles in food are also cannot be put on the market until they have undergone safety testing.

For an excellent review of US regulation of nanotechnology, see "Racing Ahead" by Steve Suppan of the Institute for Agriculture and Trade Policy.

A timeline of the history of nanotechnology can be found at

Toxicological Perspective

Thousands of Carbon nanotubes adhering into mats (Opensource Handbook of Nanoscience and Nanotechnology)

Why are some nanoparticles toxic?

The study of the toxicology of nanoparticles has only really begun to gather momentum very recently. There is also not a massive base of knowledge to build upon, for the properities of a nanoparticle are often quite different than the properties of the larger counterpart of the same particle. In effect, nanoparticles need to be treated as entirely new substances, and the toxicology of many nanoparticles remains unknown.

To date, studies have shown that the toxicity of a nanoparticle is largely dependent on the size, shape, and coating of a nanoparticle.


Nanoparticles are generally more toxic than larger particles of the same chemical. Because they are so small, nanoparticles have a much higher surface to volume ratio than the larger version of the chemical, which increases their "intrinsic toxicity."

Their tiny size also allows nanoparticles to penetrate cell membrane with relative easy. This is especially concerning considering the widespread use of nanoparticles in skin care products and sunscreen.


Shape is thought to be an important factor in how nanoparticles interact with other substances, but research into shape is still preliminary. However, nanoparticles shaped like tubes, or nanotubes, have been found to be highly toxic to lungs, and perhaps carcinogenic.

Known Health Risks


Zinc oxide and Titanium dioxide nanoparticles are used extreamly widely in sunscreens. These nanoparticles form a thin, near-invisible film when applied to skin, which makes the sunscreen invisible. Nanoparticles, by eliminating unsightly white streaks from sunscreen, have become a mainstay of the industry.

The nanoparticles used in sunscreens have been found to:

*Damage human colon cells
*Damage brain stem cells in mice
*Easily penetrate human skin, entering the blood stream, and posing a threat to the heart, liver, and red blood cells.
*Travel from mothers to unborn fetuses

More information about the health risks of sunscreen can be found at the website Friends of the Earth


Nanotechnology is considered to be one of the most cutting edge fields of research in medicine, for they enable medical action on an extremely small and presise scale. Nanotechnology is used to deliver drugs and genes, engineer tissue, aid with MRI scans, and are even (experimentally) being used to fight cancer.

Though it is an exciting field of study, it is not without risk. A study in 2007 found that silica nanoparticles damaged DNA, increasing the risk of breast cancer. Most research into the health risks of medical nanotechnology is still preliminary.

More information about the medical uses of nanotechnology can be found at The Journal of Nanobiotechnology


Nanotechnology is being increasingly used in food cultivation, processing, packaging, and supplementation.

Other Household Items

Silver nanoparticles are embedded in cloth to make it odor-resistant. These nanoparticles have been found in commercially available materials made from cotton,polyester, nylon, Spandex, and other synthetics.

Environmental Impact

Little is known about the environmental impact of nanoparticles, for few studies have been conducted on the topic. Dr. Linda Birnbaum, the director of the National Institute of Environmental Health Sciences and the National Toxicology Program, made the following statement about nanomaterials:

"We currently know very little about nanoscale materials' effect on human health and the environment. The same properties that make nanomaterials so potentially beneficial in drug delivery and product development are some of the same reasons we need to be cautious about their presence in the environment"

The process of manufacturing nanomaterials has a high environmental cost, for it consumes large amounts of energy and water. It also generates substantial amounts of toxic waste

How to Minimize Your Risk from Nanoparticles

Check the Packaging

Though nanoparticles can act quite differently than their larger chemical versions, they are usually not differentiated on the ingredients list of many products on the market in the US. The larger version of the chemical is usually listed, but consumers are left in the dark about whether the product uses nanoparticles or not.

However, there are several red flags which hint that nanotechnology is used in a product:

Current Events


External Links

North American Agencies

Non-Governmental Agencies