When combined into a pile of millions, those small quantities of hazardous substances in obsolete computer equipment can pose a great environmental problem if not properly disposed.
Lead, for example, can be found in picture tubes, display screens, solders and capacitors. The substance causes birth defects and learning disabilities in the young, and paralysis and death in large doses.
Cadmium and mercury also are present in batteries and the color-generating layers of certain computer displays, although they have been proven to damage the nervous system and are toxic in high doses.
CFCs (freons) sometimes are used to wash printed circuit boards and manufacturing expanded foam for packaging. But CFCs break down ozone, which thereby can lead to increased ultraviolet light reaching the earth and contributing to skin cancer.
Brominated flame retardants are present in printed circuit boards, cabling, casings and housings, and delay the spread of fire. But up to 30 percent of the plastics in a computer casing can consist of flame-retardant substances, which are related to another group of toxins: PCBs. Flame retardants have been found in human blood, and it is believed that they can disturb fetal development.