The toxicity of e-waste is one of the biggest concerns. Hazardous chemicals associated with electronics include polyvinyl chlorides, mercury, cadmium, chromium, and lead, just to name a few. And when e-waste byproducts leach into ground water, are burned, or get mishandled during recycling, bad things can happen. Health problems associated with such toxins include impaired mental development, cancer, and damage to the lungs, liver, and kidneys.

Source: What’s Going On with Electronic Waste? | Materials content from Machine Design