Small is, well, not so good.

Nanomaterials could pose health risks, need more oversight, council says
Last Updated: Thursday, July 10, 2008 | 11:12 PM ET
CBC News

Not enough is known about the health and environmental effects of nanomaterials and nanoproducts, says a new report released Thursday, and more must be done to regulate items that contain them.

The report, released by the Council of Canadian Academies — a not-for-profit organization whose mandate is to provide independent, expert assessment of the science underlying matters of public interest — identified major gaps in knowledge about the safety of nanomaterials.

The council’s reports are commissioned by the Canadian government.

A nanometre (nm) is a unit of measurement useful only for measuring the very small.

It’s too small even to measure human cells practically. A red blood cell, among the smallest in the body, is up to 8,000 nm wide.

It is useful for very small biological and technological objects:

A single double-helix strand of DNA is about 2.5 nm wide.
The smallest transistors on the microprocessors of computers currently sold are 45 nm long.
An AIDS virus (HIV) is about 120 nm in diameter.
The depth of the pits on the surface of a CD is 125 nm.
Nanoparticles are microscopic, often engineered particles that are measured by the nanometre, or a billionth of a metre. They have a variety of commercial applications: they’re used in stain-resistant fabrics, in skincare products like anti-aging creams and sunscreens, as delivery mechanisms for drugs and to improve such things as the functioning of car exhaust systems.

As of April 2008, more than 600 nanotechnology-based consumer products were known to exist, according to the council.

Because nanoparticles are so small, they have the potential to migrate beyond the products in which they are used, such as into the human body or the environment — and that is where their effects are unknown, says the report.

Another implication of the small size of nanoparticles is that they have different chemical properties than larger particles of the same compound. Titanium oxide nanoparticles in sunscreen, for example, are transparent to visible light, but absorb UV light. The same chemical in its conventional form is thick, white and opaque, and is used in house paint.

A chemical in nanoparticle form has a much larger surface area than the same amount of that chemical in larger chunks. In the same way that powdered sugar dissolves faster in water than sugar cubes, chemical reactions involving nanoparticles can take place much more quickly, meaning they could be much more reactive, and possibly more toxic.

The report says that chemicals that have been reviewed and approved may have very different properties in nanoparticle form, and may have to be reviewed again before they hit the market.

“There has been no identification of unique biological effects associated with exposure to nanomaterials, but there is still a poor understanding of the pathways by which these effects may occur,” the report reads.

“Changes in the potential for nanomaterials to cause harm at different stages — from production, through usage, to final disposal — implies the need for a full, life-cycle approach to risk assessment,” write the authors.

The council is calling for:

Development of standardized definitions and nomenclatures for nanomaterials to help regulators oversee these materials.
Consistent monitoring of the exposure of employees and the public to nanomaterials.
Alteration of current regulations to reflect the new chemical structures of materials.
Canada to work collaboratively with other countries to study and regulate nanomaterials.
The report, Small is different: A science perspective on the regulatory challenges of the nanoscale, is sponsored by Health Canada. It has been sent to the federal government for review.

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