Risker med nanoteknik

Nanoteknik är hett, men det finns vissa risker: "Among the large array of nanomaterials and processes, the quantum dots (QD) are of particular importance for their possible therapeutical and diagnostic medical applications. The QD owe their potential medical benefits to their specific physico-chemical properties. These nanoparticles consist of a metalloid core and a shell that surrounds the core and renders the QD bioavailable. The further addition of a specific coating can give the QD a desired bioactivity which is essential for promising medical applications such as targeted drug delivery and in vivo biomedical imaging. But the nascent nature of QD applications and the growing prevalence of nanomaterials in the society unveil the need for understanding the potentially harmful effects that these materials may have on human health and the environment. In this context, a recent toxicological review of QD was undertaken in order to elucidate their potential heath and environmental risks. In summary, the studies reviewed suggest that: QD toxicity depends on multiple factors including their physico-chemical properties (e.g. size, charge, concentration, outer coating bioactivity, and stability) and environmental conditions. Human exposure to QD may result from environmental, workplace and therapeutic exposure. There may be a risk of bioaccumulation of these materials within organs and tissues (e.g. in lungs) with still unexplored or underexplored health risks. Introduction of QD into the environment may occur via waste streams from industries, research and clinical settings. The persistence of these materials in the environment may be quite long and the environmental exposure will depend on the partition of QD between water, air, and various soil types. The main concern of QDs regards their content in metals, such as cadmium or selenium that are known to cause adverse effects on the environment and vertebrates, including humans. Consequently it is the stability of the metalloid core-coating complexes that may render QD potentially harmful. In particular, the oxidative, photolytic, and mechanical stability of the QD coating and metalloid core will be significant factors in assessing the risk of QD in the real-world exposure scenarios. Some in vitro studies suggest the QDs cytotoxicity, namely in the case of prolonged exposure. " Hardman, R. (2006) « A toxicologic review of quantum dots: toxicity depends on physicochemical and environmental factors », Environmental Health Prespectives 114:165–172.