fertilizer Substance that adds inorganic or organic plant nutrients to soil and improves its ability to grow crops, trees, or other vegetation. See commercial inorganic fertilizer, organic fertilizer.

hazard Something that can cause injury, disease, economic loss, or environmental damage. See also risk.

hazardous waste Any solid, liquid, or containerized gas that (1) can catch fire easily, (2) is corrosive to skin tissue or metals, (3) is unstable and can explode or release toxic fumes, or (4) has harmful concentrations of one or more toxic materials that can leach out. See also toxic waste.

landfill See sanitary landfill.

municipal solid waste Solid materials discarded by homes and businesses in or near urban areas. See solid waste.

PCBs See polychlorinated biphenyls. 

plasma An ionized gas consisting of electrically conductive ions and electrons. It is known as a fourth state of matter.

Polychlorinated biphenyls (PCBs) Group of 209 different toxic, oily, synthetic chlorinated hydrocarbon compounds that can be biologically amplified in food chains and webs.

radioactive waste Waste products of nuclear power plants, research, medicine, weapon production, or other processes involving nuclear reactions. See radioactivity.

Resource productivity See material efficiency.

sanitary landfill Waste disposal site on land in which waste is spread in thin layers, compacted, and covered with a fresh layer of clay or plastic foam each day.

solid waste Any unwanted or discarded material that is not a liquid or a gas. See municipal solid waste.

toxic waste Form of hazardous waste that causes death or serious injury (such as burns, respiratory diseases, cancers, or genetic mutations). See hazardous waste.