http://www.latimes.com/business/la-fi-design21jan21.story

Hazardous components
Electronic waste such as cellphones, computers and TV sets, though a tiny portion of the total solid waste stream, contributes about 70% of the nation's hazardous waste. Here's a list of select harmful chemicals contained in common consumer electronics. Some materials, such as polyvinyl chloride, or PVC, release harmful dioxins when incinerated.
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Computers
Harmful substances: Lead, mercury, cadmium, polybrominated diphenylethers
Sources: Circuit boards, connectors, cables
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CRT monitors
Harmful substances: Lead, hexavalent chromium, barium
Sources: Glass, soldering
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Flat panel monitors
Harmful substances: Mercury, lead
Sources: Light bulbs, switches
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Digital cameras
Harmful substances: Polyvinyl chloride, lead acid, cadmium, lithium
Sources: Casings, batteries
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Cellphones
Harmful substances: Antimony, arsenic, lead, beryllium, cadmium, copper, zinc
Sources: Batteries, circuit boards
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Digital music players
Harmful substances: Arsenic, lead, cadmium
Sources: Batteries, circuit boards
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Source: Silicon Valley Toxics Coalition