Toxic torts are one of the fastest growing segments of plaintiffs' filings in the American legal system. In the last century when chemicals became pervasive in our homes and workplaces, their impact was essentially unknown. Science, medicine, and the law are finally catching up, and we are rapidly learning about the massive, adverse impact of these chemicals on the health of all Americans. As the identification of exposure sources becomes increasingly comprehensive, the techniques available to measure the extent of exposure, determine the pathways by which exposure occurs, and establish causation have also greatly advanced.