Nanotechnology and nanomaterial toxicity

Abstract

Nanotechnology, a field of research and innovation concerned with building 'things' - generally, materials and devices - on the scale of atoms and molecules. Nanotechnology is hailed as having the potential to increase the efficiency of energy consumption, help clean the environment, and solve major health problems. It is said to be able to massively increase manufacturing production at significantly reduced cost. The new and unique applications offered by nanotechnology in diverse areas have made it so popular that it is being applied today in almost all aspects of daily life. Although the small size and subsequent larger surface area of nanoparticles endow them with some highly useful and specific properties, it also renders them more active leading to unexpected and unanticipated consequences on interaction with biological systems. The biokinetics of nanoparticles are different from larger particles. When inhaled, they are efficiently deposited in all regions of the respiratory tract; they evade specific defence mechanisms; and they can translocate out of the respiratory tract via different pathways and mechanisms (endocytosis and transcytosis). Some of these nanoparticles not only possess inflammatory and pro-oxidant potential for biological systems, but also have antioxidant activity, which can explain early findings showing mixed results in terms of toxicity of nanoparticles to environmentally relevant species. Manufactured nanomaterials are likely to enter the environment for several reasons. Some are and others will be produced in tons, and any material produced in such mass quantities is likely to reach the environment from manufacturing effluent or from spillage during shipping and handling. They are being used in personal-care products such as cosmetics and sunscreens and can therefore enter the environment on a continual basis from washing off of consumer products. They are being used in electronics, tires, fuel cells, and many other products and it is still unknown whether some of these materials may leak out or be worn off over the period of use. They are also being used in disposable materials such as filters and electronics and may therefore reach the environment through landfills and other methods of disposal. The fate of nanomaterials in aqueous environment is controlled by many biotic/abiotic processes such as solubility, interactions between the nanomaterials and natural/anthropogenic chemicals in the ecosystem. Although humans have been exposed to airborne nanosized particles throughout their evolutionary stages but such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source of toxicity through inhalation, ingestion, skin uptake, and injection of engineered nano-materials. Information about ecological risk, safety and potential hazards is urgently needed. Additional considerations for assessing safety of engineered nanoparticles include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. Before unknowingly dumping a huge amount of dangerous nanomaterials into the environment, we need to investigate the solubility and degradability of engineered NPs in soils and waters, to establish baseline information on their safety.