LEDs Exceed California Hazardous Waste Standards

After a recent study finding that light-emitting diodes (LEDs) exceed California’s hazardous waste standards, researchers at the University of California’s Davis and Irvine campuses conclude that LEDs should be classified as hazardous waste. The leachability test, whose results were published in

Environmental Science and Technology, looked at 5mm pin-type LEDs, including nine different colors and intensities. Using standard test procedures, the LEDs were pulverized and mixed with replicated landfill acids to determine the type and quantity of metals likely to leach out in a landfill. Only one LED failed by federal standards—low-intensity red LEDs leached 186 mg/L of lead; the limit is 5 mg/L. Eight LEDs failed by California standards, which account for not just lead but also copper, nickel, and silver. Only low-intensity yellow LEDs passed both federal and California standards. Although the research doesn’t point to hazards while the products are in use, the researchers suggest that LEDs be redesigned without toxic materials, and recycling and recovery programs be instituted to keep LEDs out of landfills. For more information, see pubs.acs.org/.