Discarding old equipment and rubbish into the landfill where it will slowly decompose over thousands of years renders the basic materials in that equipment inaccessible and unable to be used in the production of new equipment. Instead, the materials must be mined or extracted and transported large distances to be smelted.
Improving the diversion from landfills of resource-intensive equipment such as electronics can provide a cheap and readily-accessible input or feedstock for the creation of new electronics and equipment.
These materials and chemicals can leach into the ground and water or be emitted to the air if they are improperly disposed of, such as in a landfill or through burning.
Not only does proper recycling ensure these materials are isolated and safely reprocessed and repurposed, it is also prevents new raw materials from having to be mined, extracted, and smelted to be used for new electronics.
The environmental toll of mining and extracting new heavy and precious metals as opposed to using recycled and repurposed scrap materials is quantified in this model.
For instance, it takes only 10% of the energy to smelt scrap PC cases into steel than it does for iron to be mined, transported, and smelted into the equivalent amount of steel -- with a lot less waste material generated.