New research shows CFLs and LED light bulbs have higher toxicity and resource depletion than incandescent bulbs

January 16th, 2013

CFL bulb

Both compact fluorescents and LED lightbulbs qualify as hazardous waste under California and EPA protocols

New research from scientists in California and South Korea, published yesterday in Environmental Science and Technology, shows that while compact fluorescent bulbs (CFLs) and LEDs have better energy efficiency than incandescent bulbs, they compare unfavorably when you look at their potential toxicity (at the end-of-life phase) and resource depletion.

First, let’s be clear that the study focused on the kinds of CFL and LED light bulbs  you can screw into a lamp used for ambient lighting, not the LEDs used to light flat screen TVs or monitors (more on that later). Also, the study did not consider toxicity in the extraction or manufacturing phase – but just on the end-of-life phase, assuming they were trashed, not recycled (since sadly, most people do put used bulbs in the trash).

Because the bulbs have very different expected lifetimes, they “normalized” their data on resource depletion and toxicity potential by using data for fifty incandescents, five CFLs, and one LED bulb. Even after normalizing their calculations, the team found that CFLs have from three to 26 times higher resource depletion and toxicity potential than incandescents and LED bulbs have two to three times higher potential.

LED bulb

Both CFLs and LEDs have higher levels of metals than incandescents have, except for Tungsten (in the filaments) and nickel:
  • CFLs and LEDs require more metal-containing components that supply power to light the bulbs
  • CFLs and LED require one or more circuit boards (adding antimony, copper, lead, iron)
  • CFLs and LEDs use copper in the coils and zinc as protective coatings to stainless steel
  • CFLs contain mercury, phosphorous, and yttrium
  • LED bulbs include a heat sink to dissipate the heat (adding aluminum)
  • LED chips include antimony and gallium
  • LEDs use barium and chromium in stainless steel, and phosphorous, silver and gold elsewhere

With so many metals used, including some critical metals, we need to see more recycling and less trashing of all these bulbs.

CFLs and LED bulbs flunk hazardous waste test
All three bulbs were tested to see if they should be classified as hazardous waste, under the protocols established by Federal EPA (the TCLP test)  and California Department of Toxic Substances Control (the TTLC methodology).  The CFLs and LED bulbs were both determined to be hazardous waste, but the incandescent bulbs were not. Both the CFLs and LED bulbs far exceeded the federal TCLP levels for lead and the California TTLC level for copper. The CFLs also far exceeded the California levels for zinc.  While the CFLs measured just below the California level for mercury, the authors state that the methods used for sampling did not capture the mercury that could have vaporized when the CFL bulb was broken. (This may mean that the primary concern could be the exposure to whomever breaks, or cleans up a broken CFL bulb, even more than what happens in the trash.)

The study evaluated the hazard based toxicity potential (on a per bulb basis), using two different methodologies. Both showed the CFLs and LEDs have higher hazard potential than incandescents because of copper, aluminum and zinc.  CFLs and LEDs also had higher scores for human and eco-toxicity potentials. “The CFLs exhibit at least 2.5 and 1.3 times higher human- and eco-toxicity potentials than the LEDs, respectively, and the CFLs and LEDs exhibit at least 2 orders of magnitude higher potentials than the incandescent bulb,” according to the report.

What about LEDs in flat panel TVs and monitors?
The next logical question is what this kind of evaluation would find if focused on the LED components that light TVs and monitors. The University of California researchers have evaluated individual pin type LEDs, like those used as indicator lights in electronics. But given that some of the impacts from the LED bulbs studied here come from the ancillary components needed not just to light one LED, but to light the bulb, we would be very curious to see studies that look at the full array LED backlights or edge lights in TVs to determine, in particular, whether they should be classified as hazardous waste or not.