Nanoparticles in sunscreens, cosmetics and hundreds of other consumer products may pose risks to the environment by damaging beneficial microbes, scientists reported Tuesday.

A study by University of Toledo researchers discovered that nano-titanium dioxide used in personal care products reduced biological roles of bacteria after less than an hour of exposure. The findings suggest that these particles, which end up at municipal sewage treatment plants after being washed off in showers, could eliminate microbes that play vital roles in ecosystems and help treat wastewater.

Nano-titanium dioxide is used in many sunscreens and other personal care products to help block ultraviolet light that can cause skin cancer.

But this new report and other scientific research suggest such characteristics may come at an ecological price.

In the paper presented Tuesday at the annual conference of the American Chemical Society in Salt Lake City, researchers Cyndee Gruden and Olga Mileyeva-Biebesheimer added varying amounts of nanoparticles to water containing bacteria. The bacteria were grown in a lab and stained with a green fluorescent.

The scientists saw significant damage to the bacteria’s cell walls after adding 10 to 100 milligrams per liter of the nanosubstance. The cell membranes changed from green fluorescent to a faint red glow, which indicates damage.

How fast the cell damage occurred was surprising, said Gruden. Although the researchers did not measure survival rates, the cell wall damage indicates the bacteria lost functionality, Gruden said.

“Bacteria do not necessarily have to die to lose their biological functions,” added Gruden.
Though most of these particles stick to solids and might be filtered out at wastewater plants, a small percentage probably escapes treatment, and those particles would be discharged into lakes, streams, oceans and other waterways, said Gruden. If the beneficial microbes were damaged, environmental and human health could be harmed.

Microbes remove ammonia from wastewater treatment systems, clean up toxic waste and reduce phosphorus in lakes, all benefits that could be hindered or lost with the presence of nanoparticles.

Another study to be presented at the conference on Thursday shows beneficial soil bacteria cannot tolerate silver, copper oxide and zinc oxide nanoparticles, also used in sunscreens and other products. Damage to the bacteria, which clean up organic pollutants, occurred at very low levels of exposure, equivalent to two drops in an Olympic-size swimming pool, according to the study conducted by scientists at Utah State University and University of Utah.

Researchers warned these particles could be toxic to aquatic life. “If you look up the Environmental Protection Agency’s risk level of copper to fish and other aquatic organisms, you are at that point of toxicity," said Utah State researcher Anne J. Anderson.

The question now, said Gruden, is whether the microbes will behave the same in the more complex environment of wastewater.

5 Comments

1. 1. millydawson 05:30 PM 3/25/09

   So what is an environmentally concerned person supposed to do in terms of sunscreen choices? My dermatologist tells me that sunscreens with physical blocks (such as zinc and titanium) are most effective and healthier choices than the screens which rely on other commonly used active ingredients.
   
   But I don't want to be wiping out bacterai that are better left alone.
   
   Some advice would be welcome.

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2. 2. pgtruspace 03:16 AM 3/26/09

   I thought a bacteriacide was a good thing.

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3. 3. ekreider 03:53 PM 4/24/09

   The best way to approach sunscreen use is to find a non-nanoparticle (micronized is ok!) zinc oxide formula that is completely free of petrochemical active ingredients. An excellent choice is Green Screen Organic Sunscreen. Read the following if you want to learn more about what to look for in safe sunscreens: http://www.kabanaskincare.com/sunscreen_safety_criteria.htm

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4. 4. nanoqed 04:36 PM 5/3/09

   The article shows NPs to act as significant bactericides in water. Recent theoretical arguments give the reason for the bactericidal action of NPs to the emission of EM radiation at low UV levels. The UV emission occurs because collisions of solvent molecules transfer thermal kT energy to the NP that cannot be conserved by an increase in temperature, and therefore conservation proceeds by the emission of EM radiation at the confinement frequency of the NP, usually beyond the UV. The damaging NPs have diameters <100 nm. The UV is an excellent bactericide, but there is a downside. Experimental data over the past decade support the theoretical arguments that NPs induce DNA damage that may lead to cancer. The US EPA should ban the use of <100 nm NPs from commercial products for human consumption. See URL: www.nanoqed.org at link NP induced DNA damage

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5. 5. nanoqed 04:36 PM 5/3/09

   The article shows NPs to act as significant bactericides in water. Recent theoretical arguments give the reason for the bactericidal action of NPs to the emission of EM radiation at low UV levels. The UV emission occurs because collisions of solvent molecules transfer thermal kT energy to the NP that cannot be conserved by an increase in temperature, and therefore conservation proceeds by the emission of EM radiation at the confinement frequency of the NP, usually beyond the UV. The damaging NPs have diameters <100 nm. The UV is an excellent bactericide, but there is a downside. Experimental data over the past decade support the theoretical arguments that NPs induce DNA damage that may lead to cancer. The US EPA should ban the use of <100 nm NPs from commercial products for human consumption. See URL: www.nanoqed.org at link “NP induced DNA damage”

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