The U.S. Department of Energy recently released a new study addressing the potential environmental impacts from landfill disposal of three light-source technologies used in residential homes: incandescent, CFL and LED. All three lamp types contained some hazardous elements which, while generally below Federal landfill limits, in some instances exceeded the more restrictive California limits.

The report, LED Environmental Testing, covers the third part of a larger DOE study to assess the life-cycle environmental and resource impacts of LED lighting products in relation to the two other types of lighting. Altogether, the three-part study found that LEDs currently have the lowest environmental impact, and that the rapid pace of LED technology improvements will widen that gap considerably over the next five years.

Parts 1 and 2 of the study, published last year, found that the energy consumed while these products are in use dominates their life-cycle energy consumption and total environmental impact, and determined that LEDs have a much smaller impact than incandescent bulbs and a slight edge over CFLs – which is expected to grow over the next few years as LED technology continues to improve.

The new study involved the disassembly and chemical testing of 22 lamps to see whether any of 17 potentially toxic elements were present in concentrations exceeding regulatory thresholds for hazardous waste. Since lamps were ground up as part of standard test procedures, thereby exposing encapsulated materials, the results represent a worst-case scenario for the elements in question leaching into groundwater. Notably, this type of testing does not provide an indication of safety during use.

Among the key findings:

* The selected models were generally found to be below restrictions for Federally regulated elements, but nearly all of the lamps (regardless of technology) exceeded at least one California restriction – typically for copper, zinc, antimony, or nickel.
* Examination of the components in the lamps that exceeded these thresholds revealed that the greatest contributors were the screw bases, drivers, ballasts, and wires or filaments.
* Concentrations in the LED lamps were comparable to concentrations in cell phones and other types of electronic devices, and usually came from components other than the LEDs themselves.

The full report is available online here, along with the Part 1 and Part 2 reports.