GLOSSARY OF TERMS AND ACRONYMS A B C D E F G H I J K L M N O P Q R S T U V W X Y Z L LC50 Lethal concentration that kills 50 percent of test animals. Liability Under Superfund, a party responsible for the presence of hazardous waste at a site is also legally responsible for acting and paying to reduce or eliminate the risks posed by the site. Light Non-Aqueous Phase Liquid (LNAPL) Liquid contaminants that are relatively insoluble and lighter than water; also known as floaters because they will float on top of an aquifer. Long-term cleanup A response action that eliminates or reduces a release or threatened release of hazardous substances that is a serious but not an immediate danger to people or the environment. This action, also known as a Remedial Action (RA), may take years to complete. Prevention and Toxics (OPPT) focuses on promoting pollution prevention efforts for controlling industrial pollution; safer chemicals through a combination of regulatory and voluntary efforts; risk reduction to minimize exposure to existing substances such as lead, asbestos, dioxin and polychlorinated biphenyls; and public understanding of risks by providing understandable, accessible and complete information on chemical risks to the broadest audience possible.