The Pew Charitable Trusts reported earlier this week that health concerns, heightened by a recent warning by the American Medical Association (AMA) are causing some local officials to consider less intense LED alternatives.

In the article written by Michael Ollove, he cites that over the last several years New York, Los Angeles, Houston, Seattle and other U.S. cities have installed high-intensity, white LED streetlights, and that many other communities are rushing to make the switch.

LEDs are up to 50 percent more energy-efficient than the yellow-orange high-pressure sodium lights they replaced. They last for 15-20 years, instead of 2-5 years, and they spread illumination evenly, enhancing visibility for drivers and pedestrians.

However, the AMA warned in June that high-intensity LEDs emit unseen blue light that can disturb sleep rythms and possibly increase the risk of serious health conditions, including cancer and cardiovascular disease. The AMA also cautioned that high-entensity LEDs can impair nighttime driving vision.

Even before the AMA warning, some researchers raised health concerns. Some noted that exposure to the blue-rich LED outside lights might decrease the secretion of the hormone melatonin in humans. Melatonin, which is secreted at night, helps balance the reproductive, thyroid and adrenal hormones and regulates the body's circadian rythm of sleeping and waking.

The Department of Energy said LEDs should be used with "prudence" but praised their overall performance. The Lighting Research Center says that the lights pose less risk than the AMA suggests.

Read the full story here.

Related links:

AMA - Guidance to Reduce Harmful Human and Environmental Effects of High Intensity Street Lighting

Office of Energy Efficiency & Renewable Energy - LED basics

Sleep Deprivation/Insomnia and Exposure to Street Lights