If knowledge is power, as the proverb goes, then the EPA’s Toxics Release Inventory (TRI) is a powerful tool indeed. Firefighters and first responders used this nearly 20-year-old public database of toxic chemical emissions to identify potential contamination hot spots after the floods of Hurricane Katrina. Residents have used it to find out what kinds of pollutants are being emitted by nearby industries. Investment companies use it to evaluate whether or not to purchase a company’s stocks. Even the Internal Revenue Service uses it to collect a pollution tax from companies that release ozone-damaging chlorofluorocarbons. Given the TRI’s extensive use, it should come as no surprise that an EPA proposal to streamline TRI regulations for the 23,000-plus facilities that report under the law has proved highly controversial. The EPA’s plan must be reported, a move that critics say would affect the value of the TRI database for the public at large. But proponents argue that the cost savings that businesses would realize from the relief in paperwork would justify any loss of data. The arguments matter, because the power of the TRI lies in the information it provides. Authorized by the 1986 Emergency Planning and Community Right-to-Know Act, the TRI doesn’t limit emissions of the more than 650 chemicals it now covers, but merely requires that they be reported by the companies that manufacture, use, or process them. However, when residents find out what is discharged by industries in their neighborhoods, they can and have used the facts to force change. Companies have altered their practices when managers see their facilities top the list for particular chemical discharges. In fact, the myriad of uses of the TRI, and its success in influencing business practices, has surprised both supporters and opponents of the original law [see “Now That You Know,” EHP 105:38–43 (1997)]. Between 1998 and 2004, the latest year for which data are available, the industries and federal facilities that report TRI data have voluntarily cut total on- and offsite disposal and other releases of TRI chemicals to the air, water, and land by 45%, or some 3 billion pounds. Since 1988, industries have cut releases of the 299 chemicals covered by the original law by nearly 60%. Because the TRI is so different from traditional end-of-pipe regulatory programs, which put limits on how much pollution can be released, it has drawn widespread praise. “Any program that the States, the Sierra Club and Monsanto can all praise is no doubt a true environmental success story,” wrote 12 state attorneys general in their comments on the proposed TRI changes.