enLIGHTenment – The Lighting Industry Trade Publication

The LED Controversy

In the upcoming year, customers may ask you questions about health concerns regarding LED lighting.

Whenever a new technology emerges and takes off like wildfire, inevitably thoughts turn to possible medical complications.

When earbuds became ubiquitous – starting with the Sony Walkman in late 1970s to more recently as ear pieces for MP4 players or mobile phones – reports were issued warning of potential hearing damage. As cell phones rose in popularity, studies were done to evaluate whether radiation emitted from cell phones causes brain tissue damage.

The lighting industry has had its share of health precautions as well, from UV exposure emanating from halogen bulbs to mercury levels in compact fluorescents, and now blue-light hazard coming from LEDs.

Since solid-state lighting technology has become mainstream for general indoor illumination, there is closer attention being paid to any possible ill effects. Your customers may ask you about the risks they might have heard, and part of your role as an LED lighting expert is to be aware of what is being said and what studies have shown so far.

 It was these conversations in the medical community regarding the possibility of retinal damage from LEDs – commonly referred to as “blue-light hazard” – that have caused many in the scientific segment of the lighting industry to take a closer look.

For example, in June 2016 the American Medical Association (AMA) issued a warning about bright white LED street lighting having, potentially, a harmful effect on human health and the natural environment. The AMA’s official statement recommends that street lighting should not have a higher correlated color temperature than 3000K. (Note: higher Kelvin temperatures have more blue in the spectral content, which makes the light appear “whiter.”) The concern arises because many major U.S. cities have opted to retrofit their street lighting with LEDs at 4000K and 5000K, which contain a high level of short-wavelength blue light.

The AMA is worried that LED light with high blue content can cause severe glare for drivers and pedestrians because it causes pupils to constrict. There is also concern for the bright white light interfering with birds’ migratory patterns and, of course, the life of sea turtles in coastal environments.

In addition, the bright white of LEDs (from high levels of blue light) is thought to suppress the production of melatonin, resulting in disruptions in sleep and circadian rhythms.

It was these conversations in the medical community regarding the possibility of retinal damage from LEDs – commonly referred to as “blue-light hazard” – that have caused many in the scientific segment of the lighting industry to take a closer look.

A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute was released in October that takes a practical, quantitative approach to evaluating light sources for blue-light hazard. The results of the study are published in the International Journal of Occupational Safety and Ergonomics in an article titled “Evaluating the Blue-Light Hazard from Solid State Lighting.”

In the study, LRC researchers John Bullough, Andrew Bierman, and Mark Rea evaluated the spectral radiant power characteristics of incandescent, fluorescent, LED, and daylight sources in terms of current blue-light hazard calculation procedures from the Illuminating Engineering Society and the Commission Internationale de l´Éclairage.

The results showed that in the majority of use cases, LEDs do not exhibit greater risk for blue-light hazard than other light sources — including incandescent. The researchers found LEDs present no special concerns for blue-light hazard over other common light sources in typical use cases because people’s natural photophobic responses — such as squinting and averting one’s gaze — limit exposure to bright light. Where photophobic responses might not occur — such as during eye surgery or with premature infants — caution is needed.

The researchers acknowledged that organizations, such as the AMA, have advised against using LEDs with correlated color temperature (CCT) exceeding 3000K, however, their LRC study found that avoiding blue-light hazard is primarily related to controlling the radiance of light sources, and much less related to spectral distribution, particularly when expressed in terms of CCT.

The LRC researchers state that CCT should not be used as a metric for characterizing the potential for blue-light hazard, citing the fact that an incandescent filament at 2856K within a clear bulb is associated with a greater risk for blue-light hazard than any white LED source — including one of 6500K.

The spectral radiance distribution must be known to estimate blue-light hazard, particularly for those cases where photophobic responses might not occur. In these cases, and for general lighting applications, the researchers recommend the use of lenses, baffles, and diffusers to mitigate glare as the primary methods for reducing the risk of blue-light hazard.

The LRC presented a Webinar that addresses the issues raised in the AMA report, including blue-light hazard. A video of the webinar is available at https://youtu.be/2BcfcONrm58.

Keeping abreast of the latest information on LED lighting is a challenge since the field is still rapidly evolving; however, you must do what you can to stay up-to-date so that you can continue to effectively serve as the LED lighting expert for all segments of customers.





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