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Nanoparticles in Sunscreens: Safety Concerns and Discoveries

Linda Crampton is an experienced teacher with a first-class honors degree in biology. She writes about the scientific basis of disease.

These are the juvenile leaves of English ivy. The plant may provide an effective and safe sunscreen containing nanoparticles.

These are the juvenile leaves of English ivy. The plant may provide an effective and safe sunscreen containing nanoparticles.

Nanoparticles and Sunscreen

Although sunlight is essential for life on Earth, it has its drawbacks. One of these is the ability of ultraviolet light to cause skin cancer. Some form of sun protection is necessary. For many people, this protection consists of sunscreen. Unfortunately, the skin can absorb some chemicals, including some potentially harmful ones found in certain sunscreens. A secretion from the English ivy plant might one day provide a safer sunblock.

Mineral sunscreens contain either titanium dioxide or zinc oxide. They are often considered to be safer than chemical sunscreens, but they have a major drawback. The minerals give the skin a white appearance, which many people find unappealing. To avoid or reduce this whitening effect, many sunscreen manufacturers use the minerals in their nanoparticle form.

Nanoparticles are tiny and sometimes behave differently from particles of normal size. Although sunscreens containing nanoparticles are often considered to be safe, some concerns and controversies exist with respect to the effects of the particles in our body. The English ivy secretion contains natural nanoparticles that block ultraviolet light and might one day be used to create a safe and perhaps less controversial sunscreen.

Some form of sun protection is essential when sunbathing. Sunscreens are the most common form of protection.

Some form of sun protection is essential when sunbathing. Sunscreens are the most common form of protection.

The information in this article is given for general interest. Anyone with questions about sunscreen safety should consult their physician.

Titanium Dioxide and Zinc Oxide Sunscreens

Sunscreens containing titanium dioxide and zinc oxide are often called mineral sunscreens because both substances are found in the Earth. In contrast, chemical sunscreens contain sunblock substances produced in a laboratory. Mineral sunscreens are also known as physical sunscreens. They act as barriers to dangerous light rays by reflecting and scattering light. In their normal form, they appear to be safe and unable to penetrate the skin.

When chemicals are reduced to nanoparticles, their properties change. The change is often beneficial, as in the case of significantly reducing the white colour of mineral sunscreens. Nanoparticles are helpful in medicine, technology, and manufacturing. The ones produced by humans (as opposed to natural ones) are a relatively new creation. In many cases, their potential uses and effects are still being explored.

Skin is made of an outer epidermis and an inner dermis. The epidermis consists of five layers. The stratum corneum is the outermost layer.

Skin is made of an outer epidermis and an inner dermis. The epidermis consists of five layers. The stratum corneum is the outermost layer.

Nanoparticles are very tiny particles between 1 and 100 nm (nanometres) in diameter. A nanonmetre is a billionth of a metre or one millionth of a millimetre. The millimetre is the smallest division on a metric ruler.

Are Nanoparticles in Mineral Sunscreen Safe?

Cosmetics companies claim that titanium dioxide and zinc oxide nanoparticles in sunscreens can’t penetrate human skin. They say that the particles form a layer on the surface of the skin instead, thereby avoiding any damage to our bodies, and that any penetration is limited to the stratum corneum. The stratum corneum is the surface layer of the skin. It's composed of dead cells filled with keratin, a protein that prevents water loss from the body. Dead skin cells are gradually shed from our body.

The majority of the recent scientific research into mineral sunscreen safety that I’ve seen supports (or roughly supports) the statements by the cosmetic companies. Most experiments show that healthy human skin is able to prevent penetration of nanoparticles or that the particles penetrate only the outer layer of the stratum corneum. Some experiments have raised questions, however.

Scientists have discovered that long exposure to a titanium dioxide sunscreen allows the nanoparticles to penetrate the skin of hairless mice. It's unclear how applicable this is to human life. Other researchers say that human skin damaged by factors such as sunburn, shaving wounds, and blemishes may absorb nanoparticles to a greater depth than healthy skin. They also say that the smaller the nanoparticles, the further they can travel into the skin.

The current situation is confusing. Some recent research suggests that the nanoparticles in sunscreens are very likely not a problem, even for people with damaged skin. Though a small number of particles might be absorbed into our body, the researchers say that the amount is insignificant for our health. Other recent reports are not quite as ready to declare the particles harmless. Hopefully, the situation will be clarified soon.

Sunlight is essential for life on Earth, but its ultraviolet radiation can be dangerous.

Sunlight is essential for life on Earth, but its ultraviolet radiation can be dangerous.

Possible Effects of Titanium Dioxide and Zinc Oxide Nanoparticles

Titanium dioxide in the form of a dry and pure powder is considered to be a possible carcinogen (cancer causer). The general public doesn't encounter the chemical in this form in sunscreens. The problem may be a concern in certain industries, however.

Two main areas are being investigated in relation to sunscreen nanoparticle safety: the production of inflammation and damage to DNA.

  • When titanium dioxide nanoparticles are injected under the skin of mice, they have been found to cause inflammation.
  • When titanium dioxide or zinc oxide nanoparticles react with ultraviolet light, they produce reactive particles that can damage DNA. DNA, or deoxyribonucleic acid, is our genetic material. Sunscreen manufacturers use coated nanoparticles, however. The coating material prevents the nanoparticles from reacting with light.
  • Not all nanoparticle coatings are equally effective. In addition, researchers are trying to discover whether some coatings are removed by the chlorine in swimming pools, as research suggests.
  • Some scientists say that we should be investigating the effects of sunscreen nanoparticles that enter the lungs or digestive tract.

At the moment, there seem to be fewer safety concerns about zinc oxide nanoparticles than titanium dioxide ones. The European Commission considers sunscreens with nano titanium dioxide to be safe for healthy, intact, or sunburned skin but says that inhalation could be dangerous. It says that powders or sprayable products containing titanium dioxide nanoparticles should not be used.

The American Cancer Society says that it's important that we choose a sunscreen that we are reasonably comfortable with and use it regularly. The society says that the potential development of skin cancer due to sunlight exposure is a far more serious concern than the possible danger of sunscreens.

English ivy is an attractive garden plant and wall covering or a noxious weed, depending on where it's located and one's point of view. The plant grows aggressively and can be invasive in some habitats. Its vertical stems form adventitious roots that enable the plant to attach to surfaces.

Features of the English Ivy Plant

English ivy (scientific name Hedera helix) is a sometimes popular and sometimes hated evergreen plant that might provide a solution for sunscreen safety concerns. The plant grows fast and is a great climber. These abilities can make it a nuisance. Rootlets extend from ivy stems to attach them to tree trunks and walls. The rootlets produce a yellow, adhesive liquid that not only enables ivy to cling to vertical objects but also contains nanoparticles that can block ultraviolet light.

Hedera helix is native to Europe and Asia but has been introduced to other parts of the world. It can grow in the shade created by trees and is sometimes a popular ground cover in dark areas. It also grows well when exposed to full sunlight. Ivy can form an attractive coat on the walls of houses and is able to climb as high as 50 meters (164 feet) in a favourable habitat. The plant needs to be trimmed frequently since its growth can quickly get out of control. When it escapes from gardens, it’s often regarded as a weed and an invasive species.

Juvenile ivy leaves have three to five lobes, but adult leaves are not lobed. Instead, they are oval and have a pointed tip, as shown in the photo below. The small flowers occur in clusters and have a green-white color. The fruit is a black, berry-like structure.

The mature leaves and flower buds of English ivy

The mature leaves and flower buds of English ivy

English Ivy Nanoparticles

The yellow secretion containing ivy's nanoparticles is produced by its adventitious roots. Adventitious roots are those that are produced in an unusual location, such as from an above-ground stem. The ones produced by ivy are short and are known as rootlets. The secretion is released by the fine hairs covering the rootlets.

Ivy nanoparticles have a diameter of 60 to 85 nm and are generally larger than those in mineral sunscreens. Mineral sunscreen nanoparticles come in a range of sizes but may be as small as 20 nm in diameter.

A Sunscreen Made From English Ivy

Mingjun Zhang was a scientist at the University of Tennessee at the time of his English ivy discoveries. He found that ivy nanoparticles block ultraviolet light from the sun much better than conventional sunscreens containing nanoparticles. In fact, the plant sunscreen may be four times better than a mineral sunscreen at protecting us from the dangers of sunlight. In addition, the ivy particles are sticky and should adhere to skin more effectively.

When he tested isolated cells, the scientist found that English ivy nanoparticles were not toxic to the cells, while titanium dioxide ones showed significant toxicity. In addition, he discovered that the ivy particles could be broken down by protein-digesting enzymes, which suggests that they would be biodegradable in the human body.

It has been suggested—but not proved—that nanoparticles from English ivy would be unlikely to penetrate skin because of their relatively large size. Another advantage of the ivy sunscreen would be the fact that it could be almost colourless, depending on the carrier liquid. Researchers are investigating additional biomedical uses of the plant particles.

English ivy rootlets produce a sticky substance that enables the plant to cling to tree trunks and vertical surfaces.

English ivy rootlets produce a sticky substance that enables the plant to cling to tree trunks and vertical surfaces.

The science is the easy part. The hard part is the economics, the millions of dollars it takes to get FDA approval.

— Joe Laszlo, Agriculture Research Service in Peoria, Illinois, via

Testing a New Sunscreen

As exciting as the University of Tennessee discoveries are, more research needs to be done. A usable English ivy sunscreen has to be created, tested, and approved. I haven't seen any news announcing that these steps have happened yet. The nanoparticles from the plant have been investigated in recent research, particularly with their respect to their ability to act as an adhesive, but not with respect to acting as a sunscreen. The particles may be useful in multiple ways.

Even when researchers have demonstrated that a substance is helpful, it may take a long time to be approved for public use by a federal agency. One reason for the delay after a potentially helpful product has been created is the safety tests that must be performed. As might be expected, heath agencies want to see that any substance put on or in the human body is safe. The testing and approval process for a product sometimes takes years and may be expensive. The quote above comes from a scientist who has discovered another natural substance that appears to act as a sunscreen.

If an English ivy sunscreen is created and if it's shown to be safe as well as effective, new commercial products may appear. Additional sunscreen choices for consumers would be a great outcome of the research and tests.


  • “Titanium dioxide and zinc oxide nanoparticles in sunscreens: focus on their safety and effectiveness" from the US National Library of Medicine
  • "Depletion Of The Protective Aluminum Hydroxide Coating In TIO2-Based Sunscreens By Swimming Pool Water Ingredients" from the Environmental Protection Agency, or the EPA
  • Sunscreen with titanium dioxide nanoparticles from the European Commission
  • Nano titanium dioxide effects from Nanomaterials (Basel) and the US National Library of Medicine
  • Support for the safe use of zinc oxide nanoparticle sunscreens from the Journal of Investigative Dermatology
  • English ivy may give sunscreen a makeover from the Eurekalert news service
  • A scientist has created a sunscreen from ivy from the news service
  • Ivy adhesive nanoparticles for biomedical applications (a grant application with details about the particles) from Grantome
  • A high-strength adhesive from the plant from PNAS and the Bioenergy Research Center

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2011 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on April 15, 2011:

Hi, RTalloni. Sunscreen safety is a big concern for me too. The English Ivy research was published in June 2010, and I haven't seen any new information since then. I'm just hoping that the research is progressing well and that new information will be available soon! Thanks for the vote.

RTalloni on April 14, 2011:

Voted up and awesome.

Since the 70s I've felt in my bones that sunscreens are unsafe! Now I know why. Thanks. Any news on when we might have an ivy sunscreen available?

I have some ivy I would give to the cause. :)

Linda Crampton (author) from British Columbia, Canada on April 10, 2011:

Thanks for the visit and the rating, Docmo!

Mohan Kumar from UK on April 10, 2011:

This is well written and captures the concerns over nanoparticles aptly. didn't know English Ivy provides a safer alternative- I've learnt something new. Thanks Alicia C -rated up/awesome!

Linda Crampton (author) from British Columbia, Canada on April 08, 2011:

Hi, Peggy W. Thanks for the rating! Yes, like you I want new and safer sunscreen options as soon as possible.

Peggy Woods from Houston, Texas on April 08, 2011:

Wow! Another concern. This is the first that I have read about nanoparticles with regard to sunscreen safety. Hope they get that English Ivy tested and if proven safe, produced as sunscreen soon. Thanks for this informative hub. Useful rating!

Linda Crampton (author) from British Columbia, Canada on March 20, 2011:

Thanks for the comment, GetSmart. I hope that scientists are able to make a sunscreen

from English Ivy nanoparticles soon too!

GetSmart on March 19, 2011:

Great research! I hope they are able to come up with an alternative soon. Living in South Florida, it would be nice to have protection that I can trust. Thanks for the promising information.

Linda Crampton (author) from British Columbia, Canada on March 19, 2011:

Yes, I feel exactly like you, Fossillady! We're told that we should be wearing sunscreen, but it's hard to decide on the best and safest kind. I certainly hope that researchers come up with new and better options very soon.

Kathi Mirto from Fennville on March 19, 2011:

Geeze, we can't win for losin, if we don't use sunscreen we're susceptible to cancer and aging skin, but if we use the chemical sunscreens our DNA and liver can be damaged. It would be great if they did come up with a formula with English Ivy! It's easy enough to grow! Great informative article Alicia

Linda Crampton (author) from British Columbia, Canada on March 19, 2011:

Thank you very much for your comment, Eiddwen.

Eiddwen from Wales on March 19, 2011:

A very well presented and interesting hub. thanks for sharing and take care.