Toxic metals are metals that are poisonous soluble compounds. They are not essential minerals and they have no biological role. Often heavy metals are categorized as toxic metals. But some lighter metals like beryllium, are also toxic. Safe limits are defined for toxic metals by the environmental protection agency (EPA). EPA has defined safe limits for two toxics, cadmium and PCBs, but only when they are land filled or land spread. Mercury limits are defined only for incineration. EPA also provides additional limits on cadmium and PCBs, as well as restrictions on toxic metals in sludge products [Natural Resources Defense Council, Inc. v. U.S. Environmental Protection Agency, 790 F.2d 289, 314 (3d Cir. 1986)].