It takes HOW long for that to break down?

We all know recycling is a good habit to get into, and doing so helps our environment. But what happens when our old electronics do end up in the landfills? How long do these things take to decompose? In short, things like glass, certain metals, and plastic never break down. By never I mean hundreds to a million years; which, in the scheme of things, might as well be never.  
Glass is known to not have a measurable decomposition period and is guessed that it will break down after a million years or more. Plastic is estimated at 100-500 years, which may not seem so bad but since plastic wasn’t invented till the early 1900’s, the piles of plastic will never visibly go down. Metal is a broad term and refers to many things. Small bits of metal found on circuit boards are obviously going to break down faster than larger pieces of metal (Phillips). Even if some of these things are actually decomposing, what is it doing to our environment?
When electronics break down they emit harmful and toxic substances like mercury, lead, cadmium, arsenic and beryllium (Phillips). With enough time, all these things make their way into the soil, air and water. What is worse about this is that a lot of e-waste isn’t being thrown into certified and regulated landfills, but instead is being shipped overseas to places like China, India, Africa and the Far East. In the US, it is estimated that roughly 50-80 percent of waste collected for recycling is being illegally shipped overseas. When this happens, it is being dumped into villages where it contaminates the environment and poisons the health of the people living there (Williams).
When we properly dispose of our electronics we are saving our precious resources and energy. “Recycling aluminum uses less than 5 percent of the energy used to make the original product.” Producing glass from crushed, used glass requires 30 percent less energy than producing it from new materials (Stark State College).” When we recycle just these two things we are keeping harmful greenhouse gas emissions out of the atmosphere and decreasing the quantity of these nearly non-decomposable materials.  

Phillips, James Lee. "Do Electronics Decompose?" Science-Demand Media. Web. 27 Nov. 2014. <>.
Stark State College. "Recycling Fast Facts." Stark State College. Web. 27 Nov. 2014. <>.
Williams, Maria. "Electronic Waste (E-Waste)." Toxipedia., 23 Mar. 2011. Web. 27 Nov. 2014. <>.