Dim Prospects

Fluorescent bulbs and light-emitting diodes (LEDs) may be energy-efficient, but their high metal content could make them more toxic to the environment than traditional incandescent bulbs when thrown out.

Government agencies are urging consumers to replace their energy-hogging incandescent lightbulbs with more efficient and longer-lasting compact fluorescent lamps (CFLs) and LEDs. CFLs, for example, require only about 30 percent as much energy as incandescent bulbs and last 10 times longer. But what happens when these “green” bulbs are used up and thrown in the garbage?

A research team studied the three types of bulbs and found that CFLs and LEDs contain more metals such as copper, lead, and zinc. Because of these high metal levels, the CFL and LED bulbs (but not the incandescent bulb) are considered hazardous waste according to US federal and California rules.

The researchers then analyzed how environmentally harmful the bulbs’ metals might be. Since incandescents last only about 10 percent as long as CFLs and 2 percent as long as LEDs, the team compared the effects of 50 incandescent bulbs to those of five CFLs or one LED. The CFLs were still 3 to 26 times more potentially toxic than the incandescents, while the LED was 2 to 3 times more potentially toxic.

“[I]t is urgent to develop more environmentally friendly products by reducing the metal content to below the threshold limits or by replacing the hazardous metals with safer alternatives,” the authors write in Environmental Science & Technology. Recycling programs could also allow these metals to be reused instead of tossed in the trash. Roberta Kwok | 2 January 2013

Source: Lim, S.-R. et al. 2012. Potential environmental impacts from the metals in incandescent, compact fluorescent lamp (CFL), and light-emitting diode (LED) bulbs. Environmental Science & Technology doi: 10.1021/es302886m.

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