When the 103d Congress convened on January 5, 1993, many observers believed that it would make up for the dismal environmental record of its predecessor. The 102d Congress had tried and failed to reauthorize the Federal Water Pollution Control Act (FWPCA), the Endangered Species Act (ESA), and the Resource Conservation and Recovery Act (RCRA). Its attempt to elevate the U.S. Environmental Protection Agency (EPA) to a cabinet-level department had been blocked in the House of Representatives, and its attempt to reform the General Mining Law of 1872 had been blocked in both houses.

Environmental regulation of pollution in the United States is often maligned as costly and ineffective. Pollution continues to plague and degrade the natural resources in the United States, and U.S. waters in particular. Nonpoint source pollution is currently the most significant source of water pollution, but it is also the most unregulated. While other discharges into U.S. waters have been dramatically reduced since the Federal Water Pollution Control Act (FWPCA) was enacted, nonpoint source pollution—caused most by runoff from agricultural operations—has increased.

One of the most fundamental tenets of toxicology is that "the dose determines the poison." This simple phrase provides the basis for the belief that all agents—chemicals and physical phenomena that are capable of producing some effect—have the potential to cause toxicity. Whether toxicity actually occurs is principally a matter of dose: the greater the exposure to a given agent, the more pronounced or severe the response of a cell or organism.