Medical abnormalities from exposure to toxic chemicals constitute a critical public health problem in our modern world. The use of toxic chemicals in agriculture, heavy industry, and other human endeavors throughout the past century has led to widespread pollution of our environment with potential disease-causing substances. New drugs also have important toxicity issues. Twenty years ago, Singer and Grunberger estimated that 65,000 chemicals were commonly used in modern society, and over 200,000 new chemicals were discovered each year. Since that time, advances in automated methods of chemical synthesis including combinatorial techniques have led to an explosion into the millions of new chemicals produced each year for end-use applications including drugs, agriculture, personal care, and nutrition. While only a fraction of these new compounds will turn out to be acutely toxic, those that do may have long-term possibilities of causing cancer and reproductive damage.