WASHINGTON — The American Medical Association recently issued a warning that high-intensity LED streetlights emit unseen blue light that can disturb sleep rhythms and possibly increase the risk of serious health conditions, including cancer and cardiovascular disease.
The AMA also cautioned that those light-emitting-diode lights can impair nighttime driving vision.
Similar concerns have been raised over the last few years, but the AMA report adds credence to the issue and is likely to prompt cities and states to re-evaluate the intensity of LED lights they install.
Nearly 13 percent of roadway lighting is now LED, according to a report prepared last year for the Department of Energy.
Many communities that haven’t yet made the switch plan to do so.
LEDs are up to 50 percent more energy-efficient than the yellow-orange high-pressure sodium lights they typically replace. They last for 15 to 20 years, instead of two to five. And unlike sodium lights, the LEDs spread illumination evenly.
Some cities say the health concerns are not convincing enough to override the benefits of the first-generation bright LED lights that they installed in the last three to eight years.
New York is one of them, although it has responded to resident complaints by replacing the high-intensity, white LED bulbs with a lower-intensity bulb that the AMA considers safe.
Scott Thomsen, a spokesman for Seattle City Lights, which is responsible for the city’s exterior illumination, dismissed the health concerns about bright-white LED lights, noting that they emit less of the problematic blue wavelengths than most computers and televisions.
Almost as soon as outdoor LEDs were made available, the federal government encouraged states and municipalities to use them, calling LEDs highly efficient for applications such as traffic lights and exit signs.
But critics say federal authorities were too quick to endorse LEDs.
The Department of Energy and the Environmental Protection Agency “put a lot of push into them,” said Michael Siminovitch, director of the California Lighting Technology Center at the University of California at Davis.
Mr. Siminovitch said the light from early-generation LEDs “really negatively impacts people’s physiological well-being.”
Lighting is measured by color temperature, which is expressed in “Kelvin,” or “K.”
The original LED streetlights had temperatures of at least 4,000K, which produces a bright white light with a high content of unseen blue light.
Now, however, LEDs are available with lower Kelvin ratings and roughly the same energy efficiency as those with higher ratings.
They don’t emit as much potentially harmful blue light and they produce a softer, amber hue.
When 4,000K and 5,000K LEDs were installed, they drew mixed responses.
Police and traffic-safety officials and many motorists liked them because they created a bright light that sharply illuminated the ground they covered.
But in many places, residents complained that the bright white light they emitted was harsh.
People described them as invasive, cold, and unflattering.
Even before the AMA warning, some researchers raised health concerns.
Some noted that exposure to the blue-rich LED outdoor lights might decrease people’s secretion of the hormone melatonin.
Secreted at night, melatonin helps balance the reproductive, thyroid, and adrenal hormones and regulates the body’s circadian rhythm.
“As a species, we weren’t designed to see light at night,” Mr. Siminovitch said.
Meanwhile, the “dark sky” movement criticizes LEDs as a major contributor to what it calls the “light pollution” that humans cast into the night sky.
In its warning, the AMA cited the melatonin issue, noting that studies have linked bright LEDs to reduced sleep time, poor sleep quality, and impaired daytime functioning.
It referred to evidence that exposure to high-intensity light at night might increase the risk of cancer, diabetes, cardiovascular disease, and obesity.
And it cautioned that intense LEDs have been associated with “discomfort and disability glare,” which might impair nighttime vision for drivers.
Finally, the AMA cautioned about the harmful effects of bright LEDs on wildlife.
“These lights aren’t just bad for us,” said Mario Motta, one of the authors of the AMA report, “they’re bad for the environment, too.”
The AMA did commend LEDs for their energy efficiency and effectiveness, but it urged cities to minimize blue-rich outside lighting and recommended the use of LEDs no brighter than 3,000K.
Guidelines: Please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Comments that violate these standards, or our privacy statement or visitor's agreement, are subject to being removed and commenters are subject to being banned. To post comments, you must be a registered user on toledoblade.com. To find out more, please visit the FAQ.