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Nanoparticles and food safety


Characteristics of Nanoparticles

Nanoparticles (NP, also known as "nanomaterials") are defined as "particles sized between 1 and 100 nanometres." Because they are extremely small, they have a very important surface-area-to-volume ratio. A large number of their atoms is therefore situated on their surface, so they have a high surface activity. Nanoparticles have different physical and chemical properties and structures from other mass materials.

These physical and chemical properties enable them to act as catalysts in biochemical reactions and define their biological activities. Moreover, owing to their small size, nanoparticles can intervene directly and use the metabolism of cells. Nanoparticles can be assimilated and move inside cells following the metabolic pathways that the cells use to function.

The specific biochemical and biokinetic characteristics of nanoparticles are behind their biological applications in new nanotechnologies for food, agriculture, medicine and toxicology. For example, food is called nanofood "when nanotechnological methods or means are used during its cultivation, production or processing."

This change of the biological activity of nanoparticles by comparison with mass materials may be positive and desired (antimicrobial and antioxidant activity, treatment support, penetration of the cell barrier to administer medication, etc.), but also negative and undesired (toxicity, oxidative stress, cell dysfunction, etc.) or even positive and negative at the same time.

Controle of nanoparticles

It is important to implement a policy to control efficiently the risks inherent to the introduction of these new technologies. This policy must be applied worldwide where nanoparticles are produced, distributed and used. At present, nanoparticle control is possible at producer level.
Important instruments for this control are as follows:
• The general physicochemical, physical and biological (toxicological) characterisation of nanoparticles
• A (quality) control based on the most important physical and chemical characteristics of the batches, combined with a controlled storage of the batches for subsequent detailed inspections
• A correct list of users, quantities, import and export of batches of nanoparticles

Gold Nanorods

At the consumer level, a "paper" traceability of nanoparticles is important (presence of nanoparticles, treatment, purchase, discharge into the environment as waste, registration of batches, import, export, etc.). Nanoparticle presence and quality control in a finished product are actually very complex processes with technology available at this time. Such control is all the more difficult for complex matrices like foodstuffs.

The diversity of nanoparticles increases considerably in parallel with the number of their applications. Their characteristics, and the risks relating thereto, depend on the combination of their chemical composition, their physical characteristics (size, shape, stability, etc.), and the matrices in which they are found. Without full (and required?) cooperation by producers at different levels with the political authorities, as well as with the laboratories concerned, it is impossible, in a crisis situation, to detect nanoparticles and to estimate or control the risks.
At present, mostly multinational producers of nanoparticles are capable of conducting a sound characterisation. Quality control in smaller companies remains uncertain.

CODA-CERVA research projects and provision of services in relation with nanoparticles

Research projects have been initiated at the Veterinary and Agrochemical Research Centre (known by the acronym "CODA" in Dutch and "CERVA" in French) to make up for the technological lag so that the results can also be checked and verified in the laboratories of the public authorities. Electron Microscopy

Under the Nano-TEM project at the CODA-CERVA Electronic Microscopy Unit, methodologies are being developed, evaluated and validated to characterise metallic nanoparticles and virus-like particles at particle level in vitro and in vivo.

Under the NanoRisk project (launched in October 2010), new technologies and an integrated approach will be developed to detect specific particles (on the nanoAg model) in food. This approach is based on a combination of preparation (concentration, purification) techniques, chemical and microscopic analysis, and risk analysis.

In the framework of the provision of services, the CODA-CERVA uses TME technology to measure the physical properties of nanoparticles that are essential for conducting a risk assessment, namely their size, shape, specific surface area, aggregation state, size distribution, and the morphology and structure of their surface area.

The CODA-CERVA Electronic Microscopy Unit applies these techniques in the Nanogenotox project geared to developing methods for determining genotoxicity. This project is paired with the Belgian contribution to the OECD Workgroup on Nanotechnology."