Special waste refers to waste that cannot be appropriately treated with consumer waste because of its size, it may lead to serious pollution, or there is a risk of injury to persons or animals. Deposition of waste implies a squandering of resources. Landfills occupy large areas of land, are associated with pollution, unpleasant odours, litter, vermin and are eyesores in the landscape. Substances in the waste deposited pollute ground water, and may cause eutrophication. Decomposing waste generates greenhouse gases as methane and carbon dioxide.
Landfills often contain hazardous substances leaching out into the surroundings.
Some of these substances are accumulating, and will sooner or later enter the food chain. Incineration of waste leads to emissions of acidic gases and heavy metals such as cadmium, mercury and lead, and of traces of organic pollutants such as PCB, PAH and dioxins. Current upward trends in waste generation must be halted and reversed in terms of both volumes and environmental hazard and damage.