Cold water poured on LED health risk claims

The respected Lighting Research Centre in the United States has issued a pointed critique of the American Medical Association’s recent warning that LED could be a health risk.

The LRC noted in its online opinion that the blue light that is emitted from LEDs is ‘probably not a concern to the majority of the population’ due to our natural sensitivity to light and slammed the AMA’s report for ‘misapplying short term metrics’.

Without fully defining both the stimulus and the response, nothing meaningful can be stated about the health effects of any light source 

The Lighting Research Centre 

Doctors at the AMC issued a statement last month indicating that it believed that the blue light emitted by LEDs may have the ability to interfere with the body’s circadian rhythm, our natural 24-hour-cycle, which regulates sleeping patterns.

The AMA also noted that the brighter residential lighting produced by LED street luminaires may impair daytime functioning and lead to a greater incidence of obesity.

However, the LRC argues that both the stimulus and the response has to be adequately defined when developing a critique, something that it believes the AMC has failed to do in its report.

‘Without fully defining both the stimulus and the response, nothing meaningful can be stated about the health effects of any light source,’ the Research Centre argues.

The LRC believes that not enough is currently known to come to any conclusion about the potential circadian disruption caused by LED.

‘LED sources dominated by short wavelengths have greater potential for suppressing melatonin at night than sodium-based light sources. However, the amount and the duration of exposure need to specified,’ the LRC continued.

The AMA recommends in its report that outdoor lighting at night, particularly street lighting, should have a colour temperature no greater than 3000 Kelvin.

However, the LRC notes in the conclusion of its statement that colour temperature is not appropriate for characterising the potential impacts of a light source on human health. This is because the CCT metric is independent of nearly all the important factors associated with light exposure, namely its amount, duration and timing.


  • Learn more about the risks of LED at this year's LuxLive exhibition in London on Wednesday 23 November and Thursday 24 November 2016. Entry is free if you preregister here

Comments 4

Without full shielding, any outdoor sidewalk or streetlight is bad. The idea is not to be "less bad" but to be "good" by using fully shielded, level mounted 2700 K or lower LED light. Let the eye see into the shadows without insult from glare. Industry must not get a reputation for not caring about the public's health and safety. Time to adapt to reality and update lighting software accordingly.

Nonsense. Surely it is far more important to ensure that drivers stay awake than fall asleep at the wheel. How many people leave their curtains open at night to let the streetlights in?

There is no question that blue light can affect circadian rhythms. The mechanism is well understood, though it involves intrinsically photosensitive retinal ganglion cells (ipRGCs), whose function was only recently identified – coincidentally, around the time that blue LEDs became practical. IpRGCs are quite separate from rods and cones, and have a broad response peaking around 450 to 480 nm, i.e. close to the wavelength of blue emitters. Patients diagnosed with some sleep disorders may be prescribed the use of a light-box of the type also used by SAD sufferers. (The purpose is to use blue light to synchronise the patient's circadian rhythm to the desired 24-hour cycle.) The light-box will contain a standard 6500K triphosphor fluorescent tube, not one of the more exotic types intended for use on plants or tropical fish. Therefore, if LEDs are to be banned for their dangerous effects, so must 'daylight' fluorescent tubes. This could be unwelcome in countries where 'daylight' tubes are the standard. It looks as if both sides in this argument have a point.

Here comes another carrier of concerns without looking to the whole but to a single possible aspect with unrealistic ambient conditions. I wonder when this will come to an end.

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