E-waste has many types of poisons built into it. Some of these toxic substances are what make the devices safe when they operate. Cathode-ray-tube televisions and computer monitors, last-century standbys of home and office, have enormous amounts of lead built into the glass to stop stray radiation from escaping. If these old TVs and PCs are improperly discarded at the dump, they can shatter and release dangerous amounts of lead into the ground and eventually into the water table. Extreme care must be taken to remove the lead from the glass and dispose of it in an ecologically sound manner.
Semiconductors in computer chips and modern circuitry also contain many poisons, including gallium arsenide, cadmium, and beryllium. Mercury is sometimes used in switches. PVC, a known carcinogen, is used in the plastic coatings of the wires and cables, and brominated flame retardants are included in other plastics, such as the outer casing of processors. If these products are burned, or fragmented and pulverized into dust—as happens in some low-tech developing-world recycling operations—they release highly toxic substances into the atmosphere. If they’re thrown into landfills and allowed to break down over time, they release the same poisons into the land and possibly into the water table.