Nano particles breach human skin, posing unknown hazards

Washington, Oct 1 : Nanoparticles so tiny that a single strand of hair can accommodate 5,000 of them can breach the human skin with impunity.

A team led by Lisa DeLouise at the University of Rochester Medical Center (URMC) showed that nanoparticles pass through the skin of a living organism, in this case a mouse, used as a model to study the damaging effects of sunlight.

The implications of nanoparticles in the body are uncertain, said DeLouise, an assistant professor of dermatology and an expert on the properties of nanoparticles, according to an URMC press release.

Other scientists have found that the particles can accumulate in the lymph system, the liver, the nervous system, and in other areas of the body. In her study, she found that the particles accumulate around the hair follicles and in tiny skin folds.

DeLouise, a chemist, points out that her study did not directly address the safety of nanoparticles in any way. "We simply wanted to see if nanoparticles could pass through the skin, and we found that they can under certain conditions," she said.

DeLouise's work is part of a broad field known as nanomedicine that is a strategic area at the URMC. The area includes research, like hers, looking at the properties of nanoparticles, as well as possibilities like new forms of drug delivery and nano-sensors that can immediately identify microbes and other threats to our health.

While nanoparticles are becoming widely used in the manufacture of consumer products, they are also under a great deal of study in research labs, and there are some processes - including ordinary candle flames - that produce them naturally.

Some of the particles are so small, less than 10 nanometers wide (a nanometer is a millionth of a millimetre), that they are nearly as small as the natural gaps between some skin cells.

The team studied the penetration of nanoparticles known as quantum dots that fluoresce under some conditions, making them easier to see and track compared to other nanoparticles.

The scientists looked at the distribution of quantum dots in mice whose skin had been exposed to about the same amount of ultraviolet light as might cause a slight sunburn on a person.

The team showed that while the nanoparticles were able to breach the skin of all the mice, the particles passed more quickly through skin that had been damaged by ultraviolet light.

These findings appeared in the September issue of the journal Nano Letters.