Nanotechnology involves the science of manipulating matter at the level of molecules, creating new and complex compounds used in all areas of industry, including the IT, food, cosmetic, beauty and many other industries.
As this technology evolves and develops, there are increasing concerns as to the potential effects these designer chemicals will have on our health.
The following article is an exert from a scientific publication on Nanotechnology, which raises questions about some of the associated potential risks of nano-based products to consumer health.
Nanotechnology has variously been described as a transformative technology, an enabling technology, and the next technological revolution. Even accounting for a certain level of hype, a heady combination of high-level investment, rapid scientific progress, and exponentially increasing commercialisation point toward nanotechnology having a significant impact on society over the coming decades. However, enthusiasm over the rate of progress is being tempered increasingly by concerns over possible downsides of the technology, including unforeseen or poorly managed risk to human health. Real and perceived adverse consequences in areas such as asbestos, nuclear power, and genetically modified organisms have engendered increasing scepticism over the ability of scientists, industry, and governments to ensure the safety of new technologies.
As nanotechnology moves toward widespread commercialisation, not only is the debate over preventing adverse consequences occurring at an unusually early stage in the development cycle, it is also expanding beyond traditional knowledge-based risk management to incorporate public perception, trust, and acceptance.
Within this context, the long-term success of ‘nanotechnologies’ (referring to the many specific applications and implementations of nanotechnology) will depend on rational, informed, and transparent dialogue aimed at understanding and minimizing the potential adverse implications to human health and the environment. A central question within this dialogue, one that has been raised in the popular media and the peer-reviewed press, is “how safe is nanotechnology?”
However, such a general and unbound question is unlikely to yield useful information on the safety of specific nanotechnologies without further contextual information. Rather, appropriate contexts need to be defined and boundary conditions set if information on the safety of specific nanotechnologies is to be developed.
This review considers the current state of knowledge on the potential risk to human health presented by nanotechnologies, and explores the robustness of current research strategies and directions to ensure the development of ‘safe’ and publicly accepted nano-based products and technologies.
Three broad areas are addressed that focus the discussion on those materials and technologies more likely to present a significant health risk. These cover materials of likely relevance to human health, nanomaterials' behavior on and in the body (loosely relating to hazard), and nanomaterials' behavior outside the body (loosely relating to exposure).
Engineered nanomaterials of relevance to human health
Nanotechnologies will likely be so diverse as to defy generic classification when it comes to evaluating potential health impact. It is therefore important to be able to define criteria that distinguish between technologies and products more or less likely to present a health risk, if we are to avoid inappropriate and possibly deleterious sweeping conclusions regarding potential impact. For example, complementary metal-oxide-semiconductor devices with sub-100 nm features, or high-resolution electron microscopes, will present a fundamentally different potential risk to human health than products containing unbound nanostructured particles, such as nanophase zinc oxide-based sunscreens. It is anticipated that nanotechnology standards being developed by organizations such as the International Standards Organization (ISO) and ASTM International will arrive at appropriate criteria in due course. In the meantime, a number of published works have hinted at or proposed working criteria.
The 2004 report on nanotechnology from the Royal Society and Royal Academy of Engineering highlighted nanotechnologies associated with unbound sub-100 nm diameter particles as being of particular interest to human health. Oberdörster et al. support this emphasis on sub-100 nm diameter particles in a discussion on the emerging field of nanotoxicology. However, it is clear from published toxicity studies that particle size alone is not a good criteria for differentiating between more or less hazardous materials and technologies. For instance, inhalation studies using rodents have demonstrated that 20 nm diameter TiO2 particles have a greater impact on the animals' lungs than pigment-grade particles with the same composition, even though both particle sizes were administered as micrometer-diameter agglomerates.
Oberdörster et al. have suggested that it is perhaps more appropriate to address the potential health impact of nanostructured particles – those having sub-100 nm scale structures – than nanometer-diameter particles. Maynard and Kuempel explore this idea further, noting that the scale-dependent properties of nanomaterials are not necessarily associated with particle diameter, but with material structure. As an example, they use open agglomerates of single-walled carbon nanotubes (SWNTs), which may be micrometers in diameter, but exhibit structure at the nanoscale that is likely to influence their behavior.
Within the context of inhalation exposure, Maynard and Kuempel propose two criteria for identifying nanomaterials that may present a unique potential risk to human health:
1 The material must be able to interact with the body in such a way that its nanostructure is biologically available;
2 The material should have the potential to elicit a biological response that is associated with its nanostructure.
Although these two criteria relate to inhalation exposure, they are sufficiently broad to encompass all potential routes of exposure, and provide a useful working framework for distinguishing between materials and products that are less likely to present a health risk and those that are more likely to have some potential for adversely affecting health. When these criteria are linked to potential exposure to the skin, respiratory system, and gastrointestinal (GI) system, categories of materials and sources begin to emerge that may present a greater risk under some circumstances. These include unbound nanometer-diameter particles (in powders, aerosols, and liquid suspensions); agglomerates and aggregates of nanometer-diameter particles, where nanostructure-based functionality is retained; aerosolized liquid suspensions of nanomaterials; and the attrition (or comminution) of nanomaterial composites through various mechanisms.
Engineered nanomaterials in the body
While quantitative risk analysis considers many factors, the potential for a material to cause harm (hazard potential), and the amount of material able to reach target organs within the body (exposure potential) are critical to understanding potential health impact. Paracelsus (1493–1541) – widely regarded as the father of modern toxicology – is credited with the statement that “all things are poison and not without poison; only the dose makes a thing not a poison”. As true now when dealing with emerging technologies as it was 500 years ago, his statement emphasizes the need to understand both how harmful a substance is, and how much of it can get into the body (and to specific organs), if risk is to be understood and managed.
Routes of entry
Three routes of entry into the body are likely to be of primary significance for engineered nanomaterials – inhalation, ingestion, and dermal penetration. Two additional routes become important when considering nanotechnology-based medical devices and drugs – injection and release from implants. Focusing on nonmedical exposure, the literature on impact associated with inhalation exposure vastly outweighs the alternative exposure routes, reflecting a current research emphasis on the health impact of airborne nanostructured materials. Whether this represents relative risk, rather than the current interests of the research community, is unclear. Certainly, the health impacts of inhaling airborne particles have long been recognized: associations between exposure to ‘very fine particles’ and lung disease were recognized by Ramazzini in the 17th century, and documented links between aerosol exposure and ill health date back to the 4th century BCE.
There has been a greater focus on the skin as a potential route of entry in recent years. The inclusion of nanoscale particles in sunscreens and cosmetics has raised concerns over possible dermal penetration of material, leading to ill health3. For example, nanoscale particles of materials such as TiO2 and zinc oxide are being used as effective ultraviolet (UV) blocking agents in sunscreens, and nanoscale liposomes are currently used as delivery vehicles in skincare products. Dermal exposure and penetration are also potential issues when handling engineered nanomaterials. Whether engineered nanomaterials in contact with the skin represent a significant risk to health depends on their ability to penetrate through the outer protective layers and reach the epidermis or dermis, and the subsequent impact they may have on the body. Tinkle et al. have shown latex particles smaller than 1 μm penetrate the outer layers of a skin sample during constant flexing. Other studies indicate that healthy, intact skin presents a good barrier against nanostructured particles. However, there are indications that hair follicles could act as a repository of nanometer-diameter particles, and that the chemistry of carrier liquids may affect penetration potential. Recently, Ryman-Rasmussen et al. have shown that nanoscale quantum dots with different sizes, shapes, and coatings penetrate through the outer layers of pig skin samples in a flow cell, and enter the epidermal and dermal layers within 24 hours. The smallest particles – only 4.6 nm in diameter – showed localization in the epidermis and dermis within 8 hours, irrespective of the coating material used (polyethylene glycol, carboxylic acid, or polyethylene glycol-amine). Larger nonspherical particles (12 nm by 6 nm ellipsoids) showed a penetration rate that depended on the coating – but particles with all three coatings were found in the epidermis and dermis after 24 hours.
Nanotech on sale
Although nanotechnology promises great breakthroughs in areas such as energy generation and storage, high performance materials and medical treatments, many will first encounter engineered nanomaterials in everyday products such as cosmetics and personal goods (such as those shown in the full version of this article - link available below), clothing, and sporting goods. A recently published web-based inventory of nano-enabled consumer products indicates that there are over 200 products on the market worldwide, ranging from computer processors to dietary supplements. The inventory, accessible at http://www.nanotechproject.org/consumerproducts, includes details of products identified by manufacturers as using nanotechnology.
Even if nanoscale particles are able to penetrate through the outer layers of the skin, there is very little information on the hazard they might present. Research using subcutaneously introduced nanoscale particles suggests that they can be transported within the lymphatic system, raising questions about how they might influence immune responses, and there are some indications that neuronal uptake and transportation may occur. However, discussions on the mechanisms of interaction and possible health outcomes are still rather speculative. Some concern has been expressed that the photogeneration of hydroxyl radicals by nanosized particles of materials like TiO2 and zinc oxide may lead to oxidative damage in the skin, although the use of surface modification in such nanoparticles has been shown to suppress free-radical generation.
Ingestion, and possibly dermal penetration, are likely to become increasingly significant exposure routes as engineered nanomaterials are used in an ever-widening range of products. A recent survey of nanotechnology-based consumer products found that, out of over 200 manufacturer-identified ‘nano’ consumer products currently available, over 30% are applied directly to the skin or eaten. In addition to products like these that are intentionally introduced to the body, little is known about the environmental accumulation of nanomaterials over product lifecycles, how this might affect exposure profiles.
To read the entire article click here or copy/paste this URL into your Browser bar. http://www.wildcrafted.com.au/Documents/Nanotechnology-Assessing_the_risks.pdf
The above article raises some alarm bells. As readers of our articles would be aware, there are constantly 'new' materials and compounds, synthetic or otherwise, being added to so called natural skin care products. This is of concern, as the consumers looking to buy ‘natural’ skin care products are looking for just that, namely, products that utilise purely natural ingredients in order to avoid causing harm to their health by consuming products containing potentially harmful chemical compounds.
Nanotechnology, while promising to revolutionise industry, as we know it, has not been tested thoroughly and there are currently no regulations governing the use of nano-based compounds, particularly in skin care or cosmetic products.
Buyer be ware...