In determining the safety of improbably small materials known as
nanoparticles, special properties associated with some of the very
smallest particles may be the key, scientists said on Sunday.

Nanotechnology, the design and manipulation of materials thousands
of times smaller than the width of a human hair, has been hailed as a
way to make strong, lightweight materials, better cosmetics and even
tastier food.

But scientists are only starting to look at the impact such tiny
objects may have. Some studies suggest nano-sized objects may have
different effects in the body than larger ones.

Traditionally, a particle is deemed nano if its diameter is between
1 and 100 nanometers — about 1/10,000 the diameter of a human hair,
and if it has properties not present in its naturally occurring
counterpart.

But a team led by researchers at Duke University in Durham, North
Carolina, believes focusing on these special properties may be a better
way to look for any potential hazards posed by nanotechnology.

“There are an infinite number of potential new man-made
nanoparticles, so we need to find a way to narrow our efforts,” said
Mark Wiesner, an engineering professor at Duke and director of the
federally funded Center for the Environmental Implications of
Nanotechnology, whose study appears in the journal Nature
Nanotechnology.

Wiesner said it appears the very smallest particles — those less
than 30 nanometers in width — are most likely to have unique
properties that could pose a risk.

“Many nanoparticles smaller than 30 nanometers undergo drastic
changes in their crystalline structure that enhance how the atoms on
their surface interact with the environment,” Wiesner said in a
statement.

He said some nanoparticles can be highly reactive with other
chemicals in the environment and can also disrupt certain activities
within cells.

“While there have been reports of nanoparticle toxicity increasing
as the size decreases, it is still uncertain whether this increase in
reactivity is harmful to the environment or human safety,” Wiesner said.

Devising a better definition of nanoparticles is important as teams
attempt to determine whether they pose a threat, he said. “We need to
be speaking the same language when assessing any unique properties of
these novel materials.”

Last December, a report by the National Research Council found
serious gaps in the government’s plan for determining if nanomaterials
pose a risk and called for an effective national plan for identifying
and managing potential risks.

Currently, more than 600 products involving nanomaterials are on the
market. Most are health and beauty products, but many researchers are
working on ways to use the materials for medical therapies, food
additives and electronics.

(Editing by Maggie Fox and Todd Eastham)