A new study (by UC Irvine’s Department of Population Health & Disease Prevention) discovered that LED light bulbs (inorganic-LEDs) contain unsafe levels of carcinogenic toxins. While LEDs do not contain mercury (like in CFL lamps), they do contain lead, arsenic and other unsafe chemicals. This means that it's dangerous to break a LED bulb, and just extrating those toxins from the earth is a destructive process.
The research found that large LEDs contain more toxins than small LEDs - but even low intensity red LED bulbs contains eight times the level of lead allowed under California state law. They state that while LEDs are great in power efficiency - we still need to find a really safe new light source. Perhaps OLEDs will be the answer?