We live in a chemical soup. On a daily basis, each of us is exposed to hundreds of chemicals, the vast majority of which have been subject to little or no testing to determine whether they are toxic to humans or the environment. Many of these chemicals will turn out to be harmless, but others will have detrimental or even devastating effects that will become apparent only with the passage of time. By introducing thousands of new substances whose health and environmental effects are poorly understood, if at all, nanotechnology will only add to the complexity of this chemical soup.

The problem of toxic ignorance is widely recognized, yet legislatures, regulatory agencies, courts, and the chemical industry have done relatively little to address the problem. Without analyzing the risks posed by chemicals before they become widely distributed, it is difficult to determine the precautions that should be taken or the scope of any health and environmental problems that may result. Experiences in which we have discovered the hazards of chemical substances belatedly – ranging from asbestos to benzene to polychlorinated biphenyls (PCBs) – illustrate the potentially broad and serious consequences of toxic ignorance.