Nanotoxicology: Hazard and risk

Rapid developments in nanotechnology have led, like other technological advances, to predictions of great benefits and also great dangers to humanity and the ecosystem. There are great prospects of benefits to society from nanotechnology and few nanotechnologies pose a direct threat to humanity or the environment. There are, however, some foreseeable hazards, especially from nanoparticles and nanotubes. The medical problems associated with the exploitation of amphibole asbestos are well known. Accumulation in lung, and thus hazard, is explained by thinness, long needle-like shape and insolubility. This allows prediction of hazard associated with exposure to carbon and other nanotubes – key new nanomaterials. Nanotubes are ‘fibres’ a few nanometres in diameter but many microns in length, with many useful properties and potential applications. However, nanotubes may have some of the properties that dictate hazard in amphibole asbestos. In contrast to hazard, risk is determined by dose and so inhalation of a sufficient dose of long nanotubes into the lungs could initiate pathological processes leading to the same diseases that asbestos causes. Modest rises in the mass of air pollution particles are associated with excess deaths and episodes of illness, the majority of which are cardiovascular rattier than respiratory. Research has taught us that nanoparticles have two characteristics setting them apart from larger particles that promote their toxicity. First, surface activity is important in determining toxicity and, mass for mass, the smaller the particles, the greater the surface; secondly, particles tens of nanometers in size can readily traverse cell membranes. Nanotechnology is likely to lead to many useful products. Some hazards to human health are foreseeable by analogy with asbestos and environmental nanoparticles. We need to determine specific regulatory regimes for protection of workers involved in the production and use of nanoparticles and nanotubes as well as for their use. Development of novel nanoparticles must proceed in tandem with assessment of any toxicological and environmental impacts. With nanotechnology, we have a unique opportunity of testing hazard and assessing and controlling risk as the technologies themselves develop.