Danish EPA Releases Report on Environmental & Health Risks for Selected Nanoparticles

Denmark's Environmental Protection Agency (DEPA)  recently released "Survey on basic knowledge about exposure and potential environmental and health risks for selected nanoparticles". The survey was written by Sonja Hagen Mikkelsen, Erik Hansen and Trine Boe Christensen of COWI A/S, Anders Baun and Steffen Foss Hansen of DTU Environment and Mona-Lise Binderup of DTU Food, all working under contract with DEPA.

Noting that "There is no single source of information that provides an overview of nanomaterials and products in Denmark or in the EU for that matter",

DEPA has therefore initiated this project to provide an overview of the existing knowledge about seven of the most common nanomaterials, their environmental and health properties, the use of those nanomaterials and the possibility of exposure of humans and the environment.

The seven nanomaterials selected as the focus of the survey are

1 - Titanium dioxide

2 - Cerium dioxide

3- Fullerenes (aka carbon balls or 'buckeyballs")

4- Nanosilver

5- Zero-valent iron

6 - Silicium dioxide

7 - Nanoclay

These nanomaterials were selected based on

1- Application volums

2- Potential human exposure

3- Potential direct discharge into the environment

4 - Expected biological effect (human and/or environment), persistence or bioaccumultion

The authors of the survey developed "profiles" for the nanomaterials, focusing on " the general characteristics and manufacture of the nanomaterial, their current uses (mainly focused at consumer products) and hazard profiles (ecotoxicity and human toxicity) . . . . The profiles included sections discussing relevant exposures from consumer products and considerations regarding the related risk."

The first two chapters of the survey, "Introduction" and "Nanomaterials Survey" discuss the nature of the nanomaterials, their use in industries, general availability of products incorporating the nanomaterials and brief summaries of earlier studies. Chapters 3-9 focus on the individual nanomaterials selected for this survey, discussing the general characteristics of a specific nanomaterial, how it is manufactured, which consumer products available in Denmark, either via a website or a bricks and mortor shop, review of toxicity studies, possible scenarios where humans and the environment might be exposed to the nanomaterials, ranging from disposal of products containing nanomaterials in landfills to the use of nanomaterial ensconced cosmetics, such as sunscreens containing titanium dioxide, and brief discussions of "risk profiles" for the selected nanomaterials. Summary sheets are found at the end of the chapters.

Chapter 10, "Exposure and risk potential", raises a point that critics of this survey will note:

. . . the range of toxicological and ecotoxicological studies available is not sufficient to allow firm conclusions with regard to the toxicity of the nanoparticles compared to their bulk counterparts. . . (emphasis added)

As one might then expect, the authors of this survey come to the conclusion that, in order to answer the questions regarding nanomaterials and risk more information and research is needed.

Nanotechnology Law Report -- Spring 2009

The Economist on Nano Safety

The November 22, 2007 issue of The Economist contains a story on nanotechnology safety entitled "A little risky business."   The article focuses on Andrew Maynard's presentation before the House Science Commitee in October, an event we covered here, and also covers the ongoing debate over the use of silver nanoparticles as an antimicrobial agent in consumer products. 

All in all, the Economist article I think provides a useful synopsis of the current dilemma surrounding nanotechnology safety.   Its safety discussion begins with a discussion of the distinction between naturally occurring nanoparticles and engineered nanoparticles:

All that sounds alarming, but assessing the risks calls for perspective. Humans are already surrounded by nanoparticles of one sort or another. Much of the food people eat is made of naturally occurring nanoscaled components. Each person breathes in at least 10m nanoparticles a minute. Most of them do no harm.

That said, I am a little disappointed that the article did not sufficiently emphasize the inconclusive nature of the animal studies on nano safety.  The article only alludes to studies that show the potential for toxicity:

[s]tudies show there is the potential for such materials to cause pulmonary inflammation; to move from the lungs to other organs; to have surprising biological toxicity; to move from within the skin to the lymphatic system; and possibly to move across cell membranes.

However, we also know that there are a number of studies that suggest that nanomaterials may not have significant toxic effects -- see, e.g., Nano Law Report's coverage of the buckyball study and the study looking at SWNTs in fruit flies

With all of that said, the article's bottom line strikes me as reasonable -- that we need to do a better job learning what the risks of nanomaterials are so that we can responsibly regulate their use and manufacture and not lose the "baby with the bathwater" in the process.

Geckos use nanotechnology?

A gecko's amazing ability to cling to walls and ceilings is an ability that scientists have studied for decades.  Recent research suggests that the gecko's abilities owe to 200 nm adhesive hairs on the gecko's feet.  While the traditional definition of nanotechnology requires that the material be smaller than 100 nm, we are willing to make an exception for the gecko. 

Nanowerk reports that researchers at the Max-Planck Institute for Metals Research in Germany have leveraged this research to create new adhesive materials:

Copying the biological adhesive mechanism, the Max-Planck scientists used the insights gained from their years of research to develop a material with a biomimetic structure that exhibits excellent adhesive qualities. The special surface structure of the material allows it to stick to smooth walls without any adhesives. Potential applications range from reusable adhesive tape to shoe soles for climbing robots and are therefore of considerable relevance to technology.

The Nanowerk article is unclear as ot whether the new material actually employs nanoscale fibers.  This actually raises an intriguing question about nanotechnology regulation;  if we accept that 100 nm is the largest "nanomaterial," then presumably gecko feet and other "almost" nanoscale materials are not subject to the regulation.  However, I am not sure whether the alleged human health hazards associated with nanomaterials sharply diminish once the particle exceeds 100 nm in length along any one axis.   

UPDATE: First EPA Regulation of Nanotechnology?

Since first being reported in the Washington Post, and relayed here, more information concerning EPA's proposed regulation of nanosilver under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) has been uncovered.

As initially reported, the EPA's Office of Pollution Prevention reversed its course from earlier statements, and ultimately decided to regulate nanosilver under the FIFRA.  EPA reasoned that because manufacturers were producing products containing nanosilver as a method of killing bacteria, such uses were properly the province of the FIFRA as a pesticide.  Nanosilver is found in several products available today, including food containers, shoes, air fresheners, and bandages.  The concern is that the silver may pose a threat to aquatic systems as a bio-accumulative toxin.

Upon further research into EPA's announcement, it has been determined that EPA plans to issue a Federal Register notice that will explain the requirements for using nanosilver as an anti-bacterial agent.  Greenwire is reporting that the rule will be issued "within the next few months."  It is expected that those falling under this new rule will need to show that the nanosilver additive will not pose an environmental risk when placed into commerce.  However, as reported in the November 23, 2006 Washington Post article, EPA states that to be subject to FIFRA regulation, there has to be a claim that the product will "kill pests" in order for it to be a pesticide.  Consequently, products containing nanosilver may not be subject to FIFRA regulation absent a claim that the product kills bacteria, viruses, or the like.

The most important piece of information to come out of this subsequent research is the knowledge that EPA will indeed begin regulating nanomaterials, and plans to do so soon.  Silver is already regulated under the FIFRA in several products as a pesticide, so for EPA to regulate forms of nanosilver is potentially a new step.  The Federal Register notice should provide additional details as to how nanosilver will be regulated under the FIFRA and the procedures EPA will use in determining which uses are subject to regulation and which are not.  It is important to note that nanomaterials are not currently regulated, however it appears as though regulation is now imminent, starting with nanosilver in anti-bacterial uses.