The enthusiasm for widespread adoption of compact fluorescent light bulbs (CFLs) is based on the promise of a significant reduction in global energy use for lighting and the related contribution in lowering greenhouse gas emissions. CFLs have become a symbol of “going green”. However, this enthusiasm gets a dose of cold water not just from those who don’t like CFLs because the government wants you to like them, but also from some who are avowed environmentalists. The reason – mercury.
CFLs, like all fluorescent lamps, contain mercury as a vapor inside the glass. Mercury (Hg) is a heavy metal that exists in several forms. Human contact with mercury, in any form, can produce toxic effects if the dose is high enough.
According to the U.S. Environmental Protection Agency, common CFL bulbs contain 3-5 milligrams (mg) of mercury. For comparison, the old thermometer that your mother stuck in your mouth contained about 500 mg. Of course, in both the light bulb and the thermometer, no harm done unless the glass breaks – that is, no harm until they get thrown in the landfill.
The EPA estimates the U.S. is responsible for the release of 103 metric tons of mercury emissions each year. Mercury in the air ends up in the water and eventually into the fish. The primary human exposure to mercury is from bio-contaminated fish. How much do CFLs contribute to this problem?
Using fluorescent light bulbs does not expose humans to any mercury. Only if the bulb breaks is mercury released into the air. The most likely place for this to happen is when the bulb ends up in the landfill. The EPA estimates that if all the CFLs sold in the U.S. in a year (almost 300 million), we’re dumped in landfills, they would add 0.12 metric tons to U.S. mercury emissions caused by humans. By comparison, over 150 million metric tons of mercury emissions come from coal-fired electric power plants.
While the toxic impact of discarded CFLs seems slight today, each new generation of bulbs requires less mercury as manufacturers employ advances in technology. Low mercury long tube fluorescents (T8, T12) have been on the market for a number of years to address the much bigger disposal problem of these bulbs, which are found in large numbers in virtually every commercial and institutional building in North America.
A persuasive argument can also be made that reduced energy demand from CFL adoption actually results in a net reduction in mercury pollution because of the lower demand on coal-fired electric power that itself is a major cause of environmental mercury.
A purest will argue that any amount of additional mercury in the environment is too much. Some states even have mandatory prohibitions on disposing fluorescent bulbs in the solid waste stream (currently California, Maine, New Hampshire, Minnesota, Vermont and Massachusetts). For more information on CFL lamp recycling options and some guidelines for safely dealing with a broken bulb, see LampRecycle.org.
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