Study looks at toxic metal content of LEDs

Feb. 14, 2011
A recently-published journal paper suggests that many LEDs should be classified as hazardous waste, but the sample size is very small and some of the conclusions drawn could easily be described as scaremongering.
A study published recently in the Environmental Science & Technology journal looks at the potential environmental impact of LEDs in terms of metallic resources, toxicity, and hazardous waste classification.

The objective of the study, carried out by researchers from both the University of California (UC) at Davis and UC Irvine, was to examine whether LEDs are to be categorized as hazardous waste under existing US federal and California state regulations, based on their metallic constituents.

The study makes interesting reading. For example, the paper states that “most LEDs would be classified as hazardous waste under California regulations, but not under US EPA federal regulations.” (Of course, this should read "most LEDs tested…").

This statement is based on the levels of metals such as lead (Pb), copper (Cu) and nickel (Ni). The study says that low-intensity red LEDs leached Pb at levels exceeding (federal) regulatory limits. However, according to California regulations, excessive levels of Cu, Pb and Ni render all the LEDs hazardous, except the low-intensity yellow devices.

Since the research has been published in a well-known journal, there’s no reason to doubt the quality of the work. Even so, it is certainly limited in scope, since the researchers only looked a total of nine 5-mm pin-type LEDs, with all nine emitting different colors.

However, a press release from UC Irvine entitled “LED products billed as eco-friendly contain toxic metals, study finds,” contains a number of statements that verge on the ridiculous.

Since the press release will doubtless by more widely read than the original paper, it’s no surprise that the story has resulted in a spate of news articles with titles such as “LEDs filled with toxic substances, study says” and “Small LED bulbs toxic, says California study.”

Oladele Ogunseitan, chair of UC Irvine’s Department of Population Health & Disease Prevention, is quoted in the UC Irvine press release as saying: “breaking a single light and breathing fumes would not automatically cause cancer, but could be a tipping point on top of chronic exposure to another carcinogen.”

He also said that “when bulbs break at home, residents should sweep them up with a special broom while wearing gloves and a mask…Crews dispatched to clean up car crashes or broken traffic fixtures should don protective gear and handle the material as hazardous waste.”

Remember, these are LED lamps. The metal-content measurements were made by grinding up the LEDs into dust and performing standard leaching and other tests.

Even the Environmental Protection Agency (EPA) has recognized that previous guidance on how to deal with compact fluorescent lamps (CFLs) was over the top. A recently-released, revised series of recommendations on how to deal with broken CFLs in the home seems entirely straightforward and sensible: in summary, you should ask people to leave the room, shut off the AC for a while and dispose of all the bits safely.

Look closer at the journal paper and you’ll see only one LED (low-intensity red) had Pb content that was vastly in excess of the relevant limits, while all the other LEDs had miniscule Pb content. This result points to a high-Pb-content solder in the low-intensity red LED. Maybe the LED industry should shift to using Pb-free solders? Perhaps more than one low-intensity red LED should have been tested?

We’re not trying to trivialize the importance of reducing or eliminating any possible hazardous risks from LED lighting, throughout the entire lifecycle. We understand the need to study whether hazardous materials could leach into groundwater if LEDs end up in landfill. But surely it’s not appropriate to recommend that a broken Christmas LED light has to be cleaned up using gloves, a mask and a special broom?