Only once in a generation does there come along a new technology that can truly change the way we think about a subject – such is the case with nanotechnology. Simply said, nanotechnology is the study of very small objects. One nanometer (nm) is one billionth of a meter, but to give some dimension, a human hair is 60,000 nm wide and nanotechnology is defined as the study of materials with one or more dimensions in the range of 1 to 100 nm. What is particularly fascinating is that although we have been using nanotechnology and have been influenced by it since the beginning of time, we are now just discovering its usefulness and how it has influenced our lives. It is as if we had lived in a science fiction movie and just discovered the presence of a parallel universe operating simultaneously with us, but in complete anonymity and unbeknownst to us. However, now that we know of the existence of this unknown force (which we may even have used to our advantage, but not knowing why it worked), our eyes now widen with amazement regarding what was really happening. Now we know how a gecko’s feet allow it to stick to glass or a ceiling, how tiny iron particles in the brains of birds act as compasses for migration, why the addition of carbon black makes car tires last longer and possibly, the cause of some mysterious deaths in humans, not attributable to other causes.
An interesting facet about nanoparticles is not just their very small size; it is also what happens when the particles get so small. The scientific explanation is that conventional Newtonian physics no longer apply at this small dimension and quantum physics takes over – this is because at this level, the individual atoms or a single molecule can play a more active role than in a “macro” particle, which could ultimately modify the behavior of the substance. This change-over has been described as if you were shrinking a cat, smaller and smaller, until it becomes a dog. That is, at this very small dimension, substances can also take on new behaviors.
There are some distinct advantages conferred to food ingredients by the addition of nano-sized particles. For example, as nanoparticles, substances are small enough to forego absorptive mechanisms that require active-energy and could pass straight though the gut wall via translocation (passing through the cells) or even between cells via what were hitherto called tight junctions – readily gaining access to the circulatory system. For example, only a small amount (~17%) of a dose of vitamin E is absorbed by the gut, but at the nano-dimension, upwards of 100% absorption could be achieved – thus saving (by 83%) on the amount of vitamin E required for addition to food.
But, like other new discoveries, there is no free lunch. At this small dimension, easy entry could be as much a curse as an attribute. That is, the body often protects itself by limiting the rate of absorption of certain chemicals. For example, some chemicals that might have fatal consequences when injected intravenously, might be safe when absorbed in small amounts by selective, regulated or a reduced rate of absorption by the gut. Also, while entry into cells may become easier, it is certainly possible that excretion of these absorbed particles could be just as inversely difficult; if for example, one cell in the kidney tries to excrete a particle into the renal tubule for eventual elimination, another kidney cell may just reabsorb the particle, setting up a cycle of perpetual excretion and reabsorption from one cell to another. In this scenario, the body could become a dumping ground for particles that, when once absorbed, can never be eliminated. Accumulation in organs such as kidney, liver or spleen would result in loss of functionality and eventual death. In addition, such small particles may gain entry into areas of the body otherwise protected by barriers, such as brain, thyroid, eye or even a fetus. Non-nano-sized particles may have not hitherto exhibited toxicity because the size of the particle was too great to traverse these barriers, but at the nano dimension, entry may be gained and toxic effects produced.
Let’s not forget the other (quantum) effects at the nanoscale. For example, it is known that at the nano-scale, gold can change to blue or red and even act as a catalyst for reactions. Just as well, other molecules can exhibit effects different from their macro counterparts; a fact that is not lost on drug companies, who are recycling formerly failed drug candidates and testing for new indications.
So, what does this mean for pet food? Again, using the vitamin E example, less ingredient may be included in the product that may have required much more ingredient because so much more would have passed through the animal, un-utilized. Also, the use of nano-sized liposomes (fat envelopes) can be used to encapsulate otherwise labile ingredients that may have gotten broken down in the harsh environment of the stomach or upper intestine. The liposomes can protect these labile particles and deliver them to selected areas following their easy access to the circulatory system. As might be predicted liposomes or simply particles at the nano-scale, tend not to settle out of suspension and can remain in suspension for much longer periods of time, even in chemically harsh environments such as acidified foods. Lastly, because at the nano-scale new biological activities are seen, many currently expensive ingredients might be replaced with other substances capable of providing the same end result at a lower price.
The next question is how will this be regulated, if at all? Because of the newness of this technology, it is likely that the American Association of Feed Control Officials (AAFCO) will rely heavily on FDA to provide safety input for any ingredients submitted to them for review. However, unlike some countries or supra-national regulatory bodies (such as the European Union), FDA has not put any strict limits in place, except to say that FDA regards nanotechnology as having sufficiently transformed an otherwise possibly safe and regulated substance into something potentially not safe nor regulated. FDA has promulgated criteria inviting manufacturers with a substance utilizing nanotechnology to discuss the candidate substance. A significant part of this discussion will likely center around the dimensions of the particle and, because most all substances do co-incidentally contain some nanoparticles, the agency will want to know what percentage of the total mass of particles contained in the ingredient will be within the “sweet spot” range of 1 to 100 nm. Probably the key question FDA will ask is if the functionality of the substance depends on a certain amount of the mass to be at the nano-scale.
While there may not be specific regulations governing the use of nanotechnology, FDA does have the final word on anything becoming a part of food and, if FDA determines a substance to constitute a hazard, the agency has the delegated power to force an item to be recalled. In fact, Michael Taylor, now Deputy Director of FDA in charge of the Center for Food Safety and Applied Nutrition (CFSAN) and the Center of Veterinary Medicine (CVM) wrote a rather extensive article on the authority of FDA to regulate a new technology such as nanotechnology.
Other agencies are concerned about nanotechnology as well, including the Occupational Safety and Health Administration (OSHA), which is concerned about worker inhalation of nanoparticles and EPA with its concern about release of nanoparticles into the environment.
Like many new technologies, nanotechnology has the potential to make our lives easier, less costly and more convenient, but we must also be aware of possible pitfalls. The author will be discussing the benefits and potential difficulties concerning the application of nanotechnology to pet food at the Pet Food Forum in Schaumburg, IL on April 16th 1:30 PM – we hope to see you there. Attendees are welcome to ask questions at the forum or simply drop the author an e-mail at firstname.lastname@example.org.
R. Taylor (2006). Regulating the products of Nanotechnology: Does FDA Have the Tools it Needs? Woodrow Wilson International Center for Scholars. Project on Emerging Nanotechnologies. http://www.nanotechproject.org/process/assets/files/2705/110_pen5_fda.pdf