Just the phrase “e-waste” makes it sound like your favorite electronics can do a lot of damage if disposed of improperly. But just what exactly is so toxic about these devices that they account for 70 percent of the overall toxic waste that you currently find in landfills?

In addition to valuable metals like aluminum, electronics often contain hazardous materials like lead and mercury. When placed in a landfill, these materials (even in small doses) can contaminate soil as well as drinking water. But let’s take it a step further and see what (and how much) toxic material is in your average electronic device.

Televisions

Back before there were plasma screen and liquid crystal display (LCD) tubes, we were all watching our Super Bowls and sitcoms on cathode ray tubes (CRT). The CRT model provided room for all your switches and wires in a box behind the screen, but it also stored a lot of lead.

According to Electronic Recyclers, a provider of e-waste recycling, approximately 20 percent of CRTs are comprised of lead, equivalent to between four and eight pounds per unit.

Combine this with the fact that the FCC is going to require all televisions to run a digital signal by February 19, 2009, and we could be looking at a lot of lead headed for landfills. Even the smallest amounts of lead can be a serious issue, and we’re talking about eight pounds per unit.

Cellular Phones

While your trusty cellular phone may not contain as much toxic material as larger electronic devices, its shelf life is only about a year and a half for the average consumer. With hip new products like the iPhone coming out all the time, it’s estimated there are over 500 million used cell phones ready for disposal.

Cell phone coatings are often made of lead, meaning that if these 500 million cell phones are disposed of in landfills it will result in 312,000 pounds of lead released. But possibly the most hazardous component of the cellular phone is the battery.

Cell phone batteries were originally composed of nickel and cadmium (Ni-Cd batteries). Cadmium is linked as a human carcinogen that causes lung and liver damage. Alternatives contain the potentially explosive lithium, or the previously stated toxic material lead.

Computers

We’ve already discussed the presence of lead in CRT computer monitors, but there are other toxic elements in play when you’re recycling that PC or Mac. Many laptops have a small fluorescent lamp in the screen that contains mercury, a toxic material when inhaled or digested.

Mercury is also contained in computer circuit boards, which also include lead and cadmium. Circuit boards can also feature batteries made of mercury, as well as mercury switches.

In just 2005, almost two million tons of e-waste ended up in landfills. While toxic materials comprise only a small amount of this volume, it doesn’t take much lead or mercury to contaminate an area’s soil or water supply. Keep this in mind when you’re figuring out what to do with those old electronic devices.