Human Toxicology and Effects of Nanoparticles - Environmental and Human Health Impacts of Nanotechnology - page 352

9

Human Toxicology and Effects
of Nanoparticles

Vicki Stone * , Martin J. D. Clift † and Helinor Johnston *

* Applied Research Centre for Health, Environment and Society, Edinburgh Napier
University, Edinburgh, United Kingdom
† Institute for Anatomy, Division of Histology, University of Bern, Bern, Switzerland

9.1 Introduction

9.1.1 Toxicology - What Is It?

Toxicology is often defi ned as the study of the noxious effects of chemical sub-
stances on living systems (Timbrell, 2002). The noxious effects of chemicals have
been recognised for many centuries, for example Paracelsus (1493-1541), a Swiss
alchemist and physician, is quoted as saying: 'All things are poison and nothing is
without poison, only the dose permits something not to be poisonous' (Klaassen,
2001). This suggests that any chemical substance has the potential to be toxic if it
reaches a suffi ciently high concentration in the body of an organism; therefore, the
relevance of dose is of prime importance when considering toxicity.

9.1.2 Particle Toxicology

It is worth noting that toxicology is not limited to dissolved chemicals, but that it
also includes particles that enter the body. For example, there are many publications
describing the noxious effects of respirable particles such as asbestos and crystalline
silica (alpha-quartz). Both of these particle types are defi ned as carcinogens by the
International Agency for Research on Cancer (IARC) due to their ability to induce
cancer following inhalation exposure (IARC, 1997, 1987).