NANOTECHNOLOGY

The risk and promise of green nanotechnology

Whether a real prospect or just a technological pipedream, environmental nanotechnology is opening up new opportunities to address current environmental concerns. Will actual results live up to expectations? And will it be possible to control risks in such a fast-evolving research field?

Contrôle visuel de l’état de surface d’un  substrat de silicium. © CNRS Photothèque/Jérôme Chatin Visual inspection of the surface state of a silicon substrate. © CNRS Photothèque/Jérôme Chatin
Bactérie (escherichia coli)ayant absorbé des nanoparticules d’oxyde de  fer. © CEREGE Bacterium (escherichia coli) after absorbing nanoparticles of iron oxide. © CEREGE
Cellule humaine (fibroblastes  dermiques) ayant internalisé des nanoparticules d’oxyde de cerium (CeO2). © CEREGE Human cell (skin fibroblasts) after absorbing nanoparticles of cerium oxide (CeO2). © CEREGE
Photo (microscopie électronique à transmission) de nanotubes de silicium aluminium formés dans les sols volcaniques. © CEREGE Photo (transmission electron microscopy) of aluminium silicon nanotubes formed in volcanic soils. © CEREGE

The British Royal Society is clear on the subject: “Until more is known about the environmental impacts of nanoparticles and nanotubes, we recommend that the release of manufactured nanoparticles and nanotubes into the environment be avoided as far as possible”(1). However, in the United Kingdom, as elsewhere in the world, the scientific community is buzzing with ideas for using nanotechnology to meet environmental challenges. “By 2010, the world market for environmental nanotechnology- based applications could well exceed €5 billion,” says David Rickerby from the Institute for Environment and Sustainability, part of the European Commission’s Joint Research Centre (JRC) in Ispra, Italy. Green nanotechnology shoulders the hopes for finding solutions to current biotope challenges and the prospect of sizeable financial gains, coupled with misgivings concerning poor environmental risk assessment, at a time of uncertainty when national and international regulations cannot keep pace with the speed of progress.

"Miracles" at every turn

Nanoparticles promise some environmental miracles, including self-cleaning coatings that size as the space between two nanoparticles. In conjunction with catalytic particles, such as cerium oxides, the filter has both a mechanical and chemical action. For soil remediation, iron nanoparticles could be introduced into polluted strata to break down pollutants like organonitrogen compounds or chlorinated hydrocarbons (such as pesticides, dioxins and polychlorinated biphenyl).

However, these promising programmes come up against three major obstacles. First, their interdisciplinary nature makes them hard to set up and finance. Secondly, they require lengthy research with no guarantee of finding economically competitive solutions. Third, the impact on the biotope of nanoparticles that are able to destructure organic substances is still unknown, particularly where oxygen is present in the soil.

What is their impact on nature?

Jean-Yves Bottero, Research Director at France’s National Scientific Research Centre (CNRS), says that “even though the soil contains numerous iron particles, the introduction of metallic iron triggers oxidation reactions and generates reactive forms of oxygen that create oxidative stress for the cells of organisms.” Although initial mechanisms of toxicity of [nanoscience and nanotechnology] and ensure that the public can benefit from the innovations that they may bring, while being protected from any adverse impacts.”

A difficult dialogue

In a context where technology is evolving so fast, is safety compatible with industrial competitiveness when some of the potential risks have already been identified? Friends of the Earth Europe complain of a “difficult” dialogue with the EU, emphasising that nanoproducts are flooding the market before any discussions have taken place, as happened in the past with genetically modified organisms (GMOs). In the view of Corinne Lepage, former French Environment Minister and Member of the European Parliament, the situation is “even worse than for GMOs, because no regulations exist for nanoproducts”. The MEP adds that associations were unsuccessful in their bid to get nanotechnology included in the EU’s REACH directive.

Some accuse such “green technology” as a ploy to avoid calling into question lifestyles and production patterns that are depleting the Earth’s natural resources. According to Jennifer Sass, senior scientist at the Natural Resources Defense Council (USA), these means of remediation could focus public attention on the responsibilities of polluters and the reasons why pollution could not have been averted.

A mammoth task ahead

While the European Commission wishes to balance industrial interests with environmental protection, the United States does not appear to share the same concern for compromise. Christine Peterson, Acting President of the Foresight Institute (USA) says that, whileEuropeans tend to prioritise the precaution principle, Americans prefer to forge ahead and resolve any problems later. Is Europe being over cautious? When an insurance company as important as Lloyd’s of London in the United Kingdom states that lack of knowledge on the environmental and health impacts of nanotechnology is a key issue for insurance companies, the time has come to introduce a risk-assessment methodology and rules.

However, not everyone agrees with the European Commission’s view that “appropriate methods” exist. According to Vicki Colvin, Director of the Center for Biological and Environmental Nanotechnology at RiceUniversity (USA), managing nanotechnologyrelated risk is a mammoth task that will take years to organise. And Mihail Roco, architect of the National Nanotechnology Initiative(5), says that regulations are lagging behind the rapid advances in nanotechnology.

This enormous scientific and legal task has only just begun and the authorities, torn between industrial interests and public concern, sometimes simply prefer to trust in the “miracle of technology” to enable them to continue with business as usual. The “green nanotechnology” concept still has a long way to go before it is fully accepted and earns its sustainable development credentials.

François Rebufat

  1. Recommendations of the report Nanoscience and nanotechnologies: opportunities and uncertainties, Royal Society – 29 July 2004. www.nanotec.org.uk/finalReport.htm
  2. See research*eu special edition The state of the ocean, December 2007, article entitled CO2 between sea and sky.
  3. Summary of the round table at the nanotechnology conference, Nanotechnologies et environnement, 20 January 2007, Paris. espaceprojets.iledefrance.fr/jahia/Jahia/NanoCitoyens/site/projets/pid/4477
  4. Nanosciences and nanotechnologies: an action plan for Europe 2005–2009. Communication from the European Commission to the Council, the European Parliament and the European Economic and Social Committee – 6 September 2007. First Implementation Report 2005–2007.
  5. A network whose objective is to lead the United States in the nanotechnology sector. www.nano.gov/

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Combinatorial toxicity of nanoparticles

En Europe, la directive REACH réglemente depuis juillet 2007 l’utilisation des produits chimiques, mais laisse de côté les nanoparticules. Avec des surfaces démultipliées et fortement réactives, des tailles permettant de pénétrer organes et cellules, ou une structure électronique entraînant des réactions biochimiques, les nanoparticules présentent des risques sanitaires et environnementaux qu'il nous est impossible de déduire de nos connaissances sur la toxicité à l’échelle macroscopique.

Pour réglementer, il faudra non seulement évaluer chaque nanoproduit, mais aussi l’ensemble des combinaisons fonctionnelles possibles avec d’autres substances qu’il peut véhiculer. Évaluer le risque environnemental dans des écosystèmes riches et variés est d’autant plus complexe que l’on méconnaît totalement les flux des nanomatériaux largués accidentellement. Comment valider une méthode expérimentale quand des évaluations in vitro ou in situ ne donnent pas déjà les mêmes résultats? Pour un sol, prendre en compte sa nature minéralogique, organique ou texturale ne rend pas simple l’établissement de protocoles génériques d’évaluation des risques.

Pour Jean-Yves Bottero, «l’impact biologique est une question de chimie entre la particule et sa cible biologique,  et il faut considérer chaque couple particule-cible séparément». Cette combinatoire rend donc l’approche des risques environnementaux particulièrement complexe. Si l’établissement de normes et de protocoles de vérification auxquels certains chercheurs aspirent semble difficile à mettre en œuvre, le projet européen Nanosafe2 ne renonce pas pour autant à avancer dans cette direction. Quatre sous-projets interdépendants se rejoignent pour détecter et caractériser les nanoparticules d’origine industrielle, établir une base de données internationale sur la toxicité et établir des protocoles d’expérimentations génériques, développer des procédés de fabrication sécurisés, et intégrer les aspects sociétaux et environnementaux. Sans englober l’ensemble des nanoparticules existantes (et à venir), ce programme se focalise sur certaines pour servir de référence et en déduire une méthodologie plus générale.



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