Nanotechnology and nanomaterials offer great opportunities in innovation and industrial growth. The whole field offers remarkable potential in tackling current and future challenges. We can see scope in energy management and its economy, in healthcare, security and of course food production. In the broadest sense of the world, nanotechnology has come to be the saviour of the world in terms of what advances may be possible or if not managed properly, the nadir of technology – a threat, the creation of ‘grey gloop’.
New products created by this technology have been of benefit to the food industry (Duncan, 2011; Ozcalik and Tihminlioglu, 2013). It is certainly innovative and has demonstrated itself to be a potent force in both in improving food safety and quality in particular. More specific applications cover the extension of shelf-life of foods, the checking and monitoring of food spoilage and the creation of novel anti-microbials. Packaging has benefited immensely from the impact.
We note applications in the agriculture and food industry are recent when compared to the impacts made in the pharmaceutical, biotechnology and drug delivery industries (Duncan, 2011). Although a food focused article, the wealth of information found in the scientific literature relating to the pharmaceutical industry should be consulted for new ideas.
What Is Nanotechnology?
Nanotechnology concerns our ability to study, analyse and manipulate materials at a sub-microscopic level. The topic relates to a plethora of technologies which concern a particular size. It looks at the manufacture and fabrication of structures using scientifically unusual materials, and the changes and manipulation wrought on these various structures. It also covers devices and materials all of which are constrained to a particular size of 1 to 100 nm in length – an important definition of ‘nano’ (Neethirajan and Jayas, 2011). A lot of materials and ingredients at the nano-scale have unusual and surprising properties and many researchers have found the properties of nanomaterials to be unpredictable and to perform differently to their counterparts at a more macro-scale.
Nanotechnology In Food Research
Two broad areas of research cover the application of nanotechnology in food generally. We have:-
- Manipulating new or familiar materials to generate ultrafine particles which can be added to food or incorporated into food packaging.
- Investigating the way nano sized ingredients interact with each other and other foods on a macro-scale. These can generate different structures and new textures.
Benefits
A number of potential benefits have been identified in food applications which use the size properties of nanotechnology. Based on pieces of evidence from initial research in the food arena, we can certainly design products with reduced fat because it is possible to design food structures replicating the mouthfeel of fat. Such an application is essential if we seek ways to reduce obesity for example by making food healthier or at least dropping its fat content overall. A number of applications have improved the delivery of nutrients by improving their solubility and absorption.
One element which we cover briefly in a moment is food packaging. Nanoparticles help improve produce stability and protect against spoilage. A prominent area of research has been with antimicrobials. Silver and zinc oxide (ZnO) nanoparticles are well established antimicrobials. How they work is still a matter of speculation ! It is thought they act on microbes by corrupting the biochemical and cellular processes of the cell. One aspect is the binding to sulphur groups (sulphydryl and disulphide functional groups) in enzymes and to membrane located proteins which are involved in transport processes. They could also disrupt DNA replication and repair, and promote oxidative stress by promoting oxygen radical formation.
There is an indirect application for nanotechnology too. Antimicrobials can be used as surface treatments in factories to protect them from corrosion and microbial contamination. They can also be manipulated into creating novel sensors. At the moment we do not yet know what the limits really are in terms of their applications and the field is ripe for considerable research.
In the future we should expect to see better targeting of nutrients to parts of the body and the creation of smart packaging. Nanomaterials could also address current and future challenges for society in energy supply, saving energy, clean water, healthcare and security.
Nanomaterials then have extraordinary potential due to their novel properties. They will provide tremendous opportunities for industrial growth and innovation.
The Safety of Nanotechnology and Nanomaterials – What Questions Should we Ask?
All new technologies come with caveats and one is whether it is safe to use. Do we fully understand the potential health and environmental risks? Are these risks going to be properly addressed? How do we make an assessment and will it be appropriate? If we have understood the risks what we can we have in place to specifically address the issue in terms of legislation and understanding?
Can Nanotechnology Be Regulated?
The Position of The European Union
Within the European Union, a European Commission (EC) regulatory review beginning in June 2008 felt that managing the possible risks from nanomaterials was already covered by current legislation. The EC would only make changes in the legislation when it was clear that there were specific rick management issues to be addressed. By Spring 2009, it was accepted by the European Parliament that the inadequate definition of the technology could lead to misunderstanding and apprehension where none should be. In response to concerns, a science-based and science-led programme to evaluate nanomaterials began. By 2011, The EC had published a definition.
The definition of a term in any context is important especially when it comes to regulations. Once a definition is in place, effective regulation is possible. However, definitions for nanotechnology cannot just be dependent on technical and scientific criteria alone. Any regulatory definition has to be understood by industry so it can decide if a material is or isn’t a nanomaterial.
The EC’s Definition Of A Nanomaterial In The Early Years
The European Commission has a generic definition for what is termed an “engineered nanomaterial”. It drew on advice from the Scientific Committee on Newly Identified and Emerging Health Risks (SCENIHR). The definition should serve for all future legislation or in fact any other initiatives at an EU and national level.
The original FIR definition of 2011 stated in Article 2(2)(t):-
‘engineered nanomaterial’ means any intentionally produced material that has one or more dimensions of the order of 100 nm or less or that is composed of discrete functional parts, either internally or at the surface, many of which have one or more dimensions of the order of 100 nm or less, including structures, agglomerates or aggregates, which may have a size above the order of 100 nm but retain properties that are characteristic of the nanoscale.
Properties that are characteristic of the nanoscale include:
(i) those related to the large specific surface area of the materials considered; and/or
(ii) specific physico-chemical properties that are different from those of the non-nanoform of the same material;.
In 2013, there was a proposed FIR update:-
“engineered nanomaterial” means any intentionally manufactured material, containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm to 100 nm.
By way of derogation:
(a) food additives covered by the definition set out in the first paragraph shall not be considered as engineered nanomaterials, if they have been included in the Union lists referred to in Article 4 of Regulation (EC) No 1333/2008 by Commission Regulations (EU) No 1129/2011 and (EU) No 1130/2011;
(b) fullerenes, graphene flakes and single wall carbon nanotubes with one or more external dimensions below 1 nm shall be considered as engineered nanomaterials.
The updated FIR definition 1363/2013 was issued by the Commission on the 12th December 2013. This was based on a generic definition which included a threshold of 50% for the proportion of nanoparticles in an ingredient. It included an exclusion for previously approved food additives. The updated FIR definition was also subject to ‘negative assent’ procedures in European Parliament (EP) and in the council. It was subsequently rejected by the EP in February 2014 and a new proposal is being developed.
Whatever the case, the definition of a nanomaterial is constantly changing.
In September 2017, the EC began a public consultation to revise the 2011 EC Recommendation on the definition of a nanomaterial. There was a 3 month public consultation period. By July 2018, EFSA (European Food Safety Authority) which is the EU’s body responsible for checking the safety of materials published its guidance on how to assess the safety of nanoscience itself and any applications. This advice is invaluable because it provides practical suggestion on what types of testing are required and the methods that can be applied. The whole guidance looks at safety assessment for both human and animal health. The specific areas covered were novel foods, food contact materials, food and feed additives, and pesticides. The interested parties for this document are the risk assessors, risk managers, and applicants. A finalized draft was expected at the end of 2019 following a examination of the document. The next phase was then a second guidance document for 2019 that focused on the environmental risk assessment for nanoscience and nanotechnology applications in both the feed as well as food chain.
Nanotechnology in the UK
In the UK, nanotechnology has been a focus for research examination particularly in regulation. The Department Of Business, Innovation & Skills (BIS) is encouraging commercialisation of this technology for the food industry. It is a key objective to exploit the advantages to the benefit of the country.
With this initiative too comes the need to understand the health and safety implications of nanotechnology. This means filling in the gaps of knowledge about the subject. A lot of UK bodies such as the Food Standards Authority (FSA), Defra, Research Councils and GO-Science are actively involved in meeting this requirement. Once they understand what the health & safety implications are, appropriate regulations can be set up. That also means generating definitions, improving them and keeping abreast of new developments so that the regulatory environment remains up-to-date. These bodies also have to decide what form of enforcement is needed to avoid over enthusiastic interpretation of the rules and regulations. Finally, all these bodies must ensure communication is received and understood by those using the technology if there is to be effective regulation.
All new ingredients including novel foods, additives and food contact materials must receive pre-market approval before being launched. Approval means each nanomaterial is independently risk assessed. A robust risk assessment demands a sound knowledge base which is mostly produced by public research.
The FSA has in the last five years commissioned a couple of projects examining the behaviour of nanoparticles in the stomach and gut. Likewise, the European Commission (EC) also funds a variety of projects to assess the safety of these materials. EFSA (European Food Safety Authority) and other non-food based organisations also provide guidance on risk assessment of these materials and in due course will produce over-arching regulations.
The European Commission Definition of Nanomaterials (NM)
Having looked at the development of the definition we should now see what the situation is in 2023 when the European Commission adopted an updated definition for a a nanomaterial (NM) on the 10th June 2022 which was based on the old definition of October 2011.
The European Commission now defines a nanomaterial (NM) as a ‘natural, incidental or manufactured material consisting of solid particles that are present, either on their own or as identifiable constituent particles in aggregates or agglomerates, and where 50% or more of these particles in the number-based size distribution fulfil at least one of the following conditions:
a) one or more external dimensions of the particle are in the size range 1 nm to 100 nm;
b) the particle has an elongated shape, such as a rod, fibre or tube, where two external dimensions are smaller than 1 nm and the other dimension is larger than 100 nm;
c) the particle has a plate-like shape, where one external dimension is smaller than 1 nm and the other dimensions are larger than 100 nm.
However, a material with a specific surface are by volume of < 6 m2/cm3 shall not be considered a nanomaterial.
The definitions applied to various materials are the following:
(a) a ‘particle’ is a minute piece of matter with defined physical boundaries; single molecules are not ‘particles’!
(b) an ‘aggregate’ is a particle comprising strongly bound or fused particles;
(c) ‘agglomerate’ means a collection of weakly bound particles or aggregates where the resulting external surface area is similar to the sum of the surface areas of the individual components.
The basic principles of the EC’s NM definition is based on the one feature common to all nanomaterials and that is size. There is no relation to hazard or risk intended. The definition was adopted as a recommendation and so is not legally binding. This definition has been brought into line with other worldwide approaches. It is however more specific and quantitative than most other definitions. It enables its implementation in a regulatory framework. The definition that was developed is ‘horizontal’ which means it is not sector-specific.
The scope of the definition is important too. It means that the origin of the material is irrelevant. The definition is not applicable to internal or surface structure in the nanoscale dimensions. It means that only the external dimensions of the particles are relevant. It does not consider nanostructures on surfaces or internal nanostructures. Only solid particles and not liquid ones are considered. Neither does the definition cover consumer products or components in which nanomaterials are integrated. In other words even if it contains a nanomaterial, the product itself does not automatically become a nanomaterial.
The definition is said to be simple but actually quite complex.
The Challenges
The first issue is identifying the constituent particles present or on their own, in agglomerates or aggregates. You have to be able to measure the external dimensions of the constituent particles in the size range from 1 nm up to at least 100 microns. It is tricky to measure the particles to decide of 50% or more fulfil at least one of the conditions in the definition. Interestingly, the volume specific surface area can be used to identify materials that are not nanomaterials.
The second issue is determining the constituent particles of a nanomaterial. The constituent particles are the morphologically identifiable particles inside an aggregate or agglomerate. To implement the EC’s NM definition, it is not necessary to distinguish between aggregates and agglomerates. The determining factor is the external dimension of the constituent particle. Mobility-based techniques cannot be used to measure the size of the constituent particles in both aggregates and agglomerates.
The Dimensions of Particulates
There are a number of techniques used to measure the external dimensions of the constituent particles. However, most instruments and techniques do not measure the external dimensions of a particle but measure other properties that are correlated with the particle dimensions.
We have:
MALS – multiple-angle light scattering
SEM/TEM – scanning and transmission electron microscopy
DLS- Dynamic light scattering
PTA – Particle tracking analysis
SAXS – Small-angle X-ray scattering
CLS -Centrifugal liquid sedimentation.
External dimensions can be represented in various ways for example as the minimal ‘Feret’s diameter’. The Feret’s diameter is the distance between two tangents on the surface of a particle. The most appropriate way depends on the particle shape. Many particle size analysis techniques produce equivalent spherical particle diameters and tend to overestimate the minimum external dimensions. Measuring the ‘wrong’ external dimension can lead to a wrong decision. Size information without defining the method used in meaningless.
The most frequently used methods are scanning or transmission electron microscopy and then light scattering methods.
Size distribution is based on particle number, mass or volume or on scatter intensity. In the EC’s definition, the size distribution is based on particle number and not on mass or any other metric.
The most appropriate methods that produce a number distribution are Sp-ICI-MS and electron microscopy.
When considering the 50% distribution by number, the median is the most relevant number.
To achieve effective implementation of the definition requires defined measurement methods and guidance which allows for implementation in legislation. This means safer products and better harmonised legislation as a result.
The EC has developed a ‘JRC Reference Report which describes requirements for particle size measurements of nanomaterials. It discusses the generic measurement issues and reviews the capabilities iof the measurement methods now available. It especially addresses:-
- measurement-related elements in the definition
- generic reliability issues in particle size analysis
- evaluation of specific measurement methods.
Internationally harmonised and standardised methods are required to ensure that the measured data for identifying nanomaterials is reliable, reproducible and mutually acceptable.
REACH (EU Legislation)
REACH is the overarching piece of legislation relating to the use of chemicals in all sectors of industry. However, different sectors have specific concerns and priorities which differ between these sectors. The sectors can be split into cosmetics, food, medical and biocides.
REACH is Registration, Evaluation, Authorisation and Restriction of Chemicals. Then, there is specific legislation for each of the sectors described above.
Food and cosmetics have their own consumer safety legislation for example. The regulation-specific concerns and priorities are reflected in various requirements.
Food is generally covered by the Novel Foods Regulation (EU) 2015/2283 and is under the auspices of EFSA, the European Food Safety Authority. EFSA authorises novel foods by placing them on an EU list (Regulation 2017/2470 Union list of novel foods). A risk assessment is performed by EFSA when asked by the European Commission.
When is comes to nanomaterials the emphasis is on their safety. The nanomaterial definition included in most pieces of legislation predates the European Commission’s recommended definition. The EC Recommendation as we have learnt previously is based on particle size. It is an overarching EC Recommendation for all sectors.
At the moment we have EFSA nanomaterial guidance. The web-site states that when test methods are applied to nanomaterials, their scientific appropriateness and the technical adaptations or adjustments that have been made in order to respond to the specific characteristics if nanomaterials have to be explained.
In 2011, there was a regulation concerning called Food Information to Consumers (EU) 1169/2011. This relates to information presented about a food to a consumer. It concerns origin, nutrition and allergens and defines labelling requirements. In the list of ingredients, any ingredient present which is by definition an engineered nanomaterial must be labelled with “(nano)” following the name of the ingredient. The legal definition of an ‘engineered nanomaterial’ refers to the definition in the Novel Foods Regulation 2015/2283.
The next piece of legislation concerns the Plastic Food Contact material Regulation (EU) 10/2011. Plastic food contact materials (FCMs) which are available in the marketplace have to the requirements of this regulation. They can only be manufactured using the authorised substances identified in the Union list in Annex 1. The material constituents cannot migrate into the food in quantities that exceed specific migration limits as stated in Annex 1. Nanomaterials have to explicitly authorised as mentioned n Annex 1 too. All the FCMs are subject too to EC Reg. 1935/2004 (FCM Framework Regulation) and EC 2023/2006 (Good Manufacturing Practice for FCMs).
References
Duncan, T.V. (2011) Applications of nanotechnology in food packaging and food safety: barrier materials, antimicrobials and sensors. J. Colloid Interface Sci. 36 pp. 1–24.
Neethirajan, S., Jayas, D.S. (2011) Nanotechnology for the food and bioprocessing industries. Food Bioprocess Technol. 4 pp.39–47.
Ozcalik, O., Tihminlioglu, F. (2013) Barrier properties of corn zein nanocomposite coated polypropylene films for food packaging applications. J. Food Eng. 114 pp. 505–13.
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