What is nanotechnology?
The UK Food Standards Agency defines nanotechnology as the manufacture and use of materials and structures at the nanometre scale. A nanometre is one millionth of a millimetre. If you shrink a grain of rice one thousand times, stop for a minute to admire your supernatural size-reducing powers and then proceed to shrink the grain a thousand times again, you will have conjured up a nanoparticle.
Nanomaterials in foods
Nanoparticles are natural components of many foods - caseins in milk come into this category, as do protein filaments in meat. They are also formed during the manufacture of many long-established processed foods, such as toffee, mayonnaise, margarine, chocolate and cheese. Natural nanoparticles make an important contribution to the character of a food. Without them, for example, toffee simply wouldn’t be toffee. This fact led food scientists to realise that artificial nanomaterials could be added to foods in order to improve their properties and make them healthier and/or more attractive to consumers.
One of the most commonly used nano-additives is titanium dioxide or TiO2. Also used as a component of paint and cosmetics, TiO2 is widely added to foods such as sweets, cheese and sauces, to improve their whiteness, opacity, brightness and sometimes flavour. Silica nanoparticles are another popular additive, found in items such as coffee creamers and a diet chocolate milk shake product, in which the silica is coated with cocoa particles to provide a low-fat but creamy chocolate flavour. The solubility and bioactivity of health promoting compounds, such as curcumin, can be enhanced by encapsulation in nanoparticles, and silver-based biocompatible nanoparticles are used to control microbial growth in beverages and during winemaking. Nanoparticles can also can also be magnetic, enabling them to remove heavy metals, such as cadmium, lead and antimony, from food and drinking water.
Potential future nano-additives include grains of salt approximately a thousand times smaller than those found in normal table salt. These tiny salt particles have a greatly increased surface area, which enhances their saltiness, meaning that consumers could reduce their salt intake without sacrificing on flavour. Researchers are also attempting to manipulate the structure of the nano-sized droplets found in mayonnaise in order to reduce their fat content.
Packaging has probably been the most active area of food nanoscience research and development over the last decade. The physical characteristics and barrier properties of packaging polymers can be significantly improved by dispersing an inert, nanoscale filler through the polymer matrix to form a nanocomposite. Fillers can include silicate and clay nanoplatelets, silica or chitosan nanoparticles, carbon nanotubes, graphene, cellulose whiskers and starch nanocrystals. For example, incorporation of nanoclay into plastic beer bottles prevents outgassing of CO2 molecules, which causes the beer to go flat; these bottles also stop oxygen from entering the beer and spoiling its flavour.
Silver nanoparticles with broad-spectrum antimicrobial activity are frequently incorporated into food contact materials, such as containers, refrigerator and dishwasher liners and chopping boards. The unique electrochemical and optical properties of nanoparticles have also led to development of smart or intelligent packaging, containing nanosensors that can detect changes in the environment surrounding the food and respond to the presence of microbial or chemical contaminants and undesirable gases, such as oxygen, or amines released from fish or meat. In addition, smart tracking devices employing, for example, encoded silica nanoparticles that can be identified by an automated reader, allow food to be monitored along the entire food chain.
Is nanotechnology safe?
Concerns have been raised that nanoparticles could be dangerous because their physicochemical properties are different to those of larger food components and their small size allows them to enter cells, such as those in the brain and liver.
Evidence for their toxicity in foods is inconclusive and fairly limited, particularly in relation to long term exposure. However, peer reviewed studies have shown that TiO2 particles can accumulate in the small intestine, exert genotoxic effects in mice and induce dose-dependent cell cycle alterations in neuronal cells. In experiments on live chickens, exposure to polystyrene nanoparticles adversely affected gastrointestinal iron absorption, and another study demonstrated that metallic nanoparticles may have a similar negative impact on digestion.
Contrastingly, in an experimental comparison of the effects of zinc oxide and silver nanoparticles on Caco-2 cells from the colon, the cells treated with silver nanoparticles demonstrated no oxidative damage; in fact, the antioxidant capacity of the cells increased at certain concentrations. In another study, silica nanoparticles did not pass through a monolayer of the same cell type after 4 hours of exposure, suggesting that they would be unlikely to pass through the gut wall.
Food companies and nanomaterials
At the moment, the extent to which companies are adding nanoparticles to their foods and packaging is difficult to assess.
In 2013, As You Sow, a UK organisation whose aim is promotion of environmental and corporate social advocacy, carried out a survey of 2500 food companies. Questions were asked about their use of nanomaterials. Most companies didn’t respond to the survey, leading As You Sow to conclude that there was a general lack of transparency about the issue. In the same year, the UK Food and Drink Federation, which represents manufacturers, claimed that to the best of their knowledge, engineered nanomaterials were not used by UK food and beverage companies.
However, in a 2014 report (“Tiny Ingredients, Big Risks: Nanomaterials rapidly entering food and farming”) Friends of the Earth claimed that there had been a tenfold increase in unregulated and unlabelled nanofood products on the American market since 2008 and that billions are being invested in such foods and in nanopackaging by major companies. The report documents that 85 food and beverage products are known to contain nanomaterials, including well-known brands. The Project on Emerging Nanotechnologies (PEN) - a joint venture of Virginia Tech and the Wilson Center in the US - keeps a running inventory of consumer products available on the market that contain nanomaterials. At the time of writing, their database, which they stress is not comprehensive, contains 7 products in the food and beverage category, 15 in the cooking/utensils section, 20 storage products and 69 nutritional supplements.
Are consumers worried?
Again this is something of an unknown. It’s possible that most consumers aren’t even aware of nanoparticles, and therefore haven’t had a chance to formulate an opinion about them. In 2014, As you Sow made sure that the shareholders of a well-known doughnut company were aware that a sugar coating used on the company’s doughnuts contained TiO2 particles, and managed to persuade 18.7% of them to vote for a resolution asking the company to identify which of its products contained nanomaterials and produce a report about the risks associated with their use. Perhaps a more general awareness will build from beginnings like this. It has been suggested that some companies might be taking a cautious approach to nanomaterials and may even be reluctant to use them at all because of the problems they faced over negative consumer attitudes to GM foods. Of course, this might also explain why many unlabelled foods containing nanoparticles may already be on the market.
The regulatory picture
Differences exist between current regulation of food nanomaterials in the US and the European Union.
FDA guidelines issued in the summer of 2014 request that companies consult with the government before launching new nanotech products, but state that the decision essentially rests with manufacturers. No requirement has been made that such products should be subject to pre- or post-market safety assessments and the FDA doesn’t demand that nanomaterials are listed on product labels.
In 2010, the US National Organic Standards Board unanimously approved a guidance document recommending that “Engineered nanomaterials be prohibited from certified organic products as expeditiously as possible.” However, at the end of 2014, the USDA National Organic Program had still not taken any action to implement this recommendation.
In November, 2014, the European Parliament Committee on Environment, Public Health and Food Safety (ENVI) approved a proposal for a moratorium on use of nanomaterials in foods, based on the precautionary principle. It states that foods containing nanomaterials should not be authorized until they are approved by the European Food Safety Authority (EFSA) and requires that special attention must be paid to food packaging containing nanomaterials, to prevent their migration into food.
New EU food labelling rules came into effect on the 13th December 2014 requiring that all engineered nanomaterials present in a food must be clearly indicated in the list of ingredients. The names of such ingredients must be followed by the word “nano” in brackets. Food businesses have been allowed a 3 year transition period smooth for adoption of the new labelling regime.
The future of nanotechnology
It’s difficult to see how the current regulatory differences between the US and the EU can continue without affecting exports of US goods into Europe. Perhaps this will be a stimulus for further regulatory developments in the US, particularly in the wake of the failure of US companies to completely win over European and UK consumers about the benefits of food nanotechnology’s novel food predecessor, GM.
As for the food companies, there are various rumours about their future plans. The concept of molecular food manufacture, in which foods are created from their basic atomic components has been around for a while, but it may be a long time before it becomes a reality. It’s envisaged that nanomachines could construct foods by synthesis at atomic level and it has even been suggested that this approach could eventually eradicate hunger.
At perhaps the slightly further out end of the spectrum of future possibilities is the concept of the smart blob. One major food company is supposed to be researching the idea that a blob could be transformed into any type of food by putting it in a microwave. The microwaves would activate nanoparticles in the blob and change its colour, shape and/or nutrient content. I’m not sure what consumers will think about this, though. However impressive the nanotechnological sophistry that might lead to its creation, at the end of the day, a blob is still a blob.
(Image Credit: amenic181 at www.freedigitalphotos.net)