Study: Light from energy saving LED's may be giving us cancer

From the “law of unintended consequences” department comes this finding, suggesting that the push for eco-friendly energy savings may be doing more harm to us than good.

Study links night exposure to blue light with breast and prostate cancer

Researchers used images taken by astronauts to evaluate outdoor lighting in Madrid and Barcelona

LED street lighting with a strong blue tint.

A study performed by an international team led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the “la Caixa” Foundation, reports a link between exposure to blue light at night and higher risk of developing breast and prostate cancer. Blue light is a range of the visible light spectrum emitted by most white LEDs and many tablet and phone screens. The results have been published in Environmental Health Perspectives.

“WHO’s International Agency for Research on Cancer (IARC) has classified night shift work as probably carcinogenic to humans. There is evidence pointing to an association between exposure to artificial light at night, disruption of the circadian rhythm, and breast and prostate cancers. With this study we sought to determine whether night exposure to light in cities can affect the development of these two types of cancer”, explains Manolis Kogevinas, ISGlobal researcher and coordinator of the study. “We know that depending on its intensity and wave length, artificial light, particularly in the blue spectrum, can decrease melatonin production and secretion”, says Martin Aubé, physics professor at CÉGEP in Sherbrooke, Canada and study co-author.

The study was conducted within the framework of the MCC-Spain project cofunded by the ‘Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública’ (CIBERESP), and includes medical and epidemiological data of more than 4,000 people between 20 and 85 years of age in 11 Spanish regions. Indoor exposure to artificial light was determined through personal questionnaires, while outdoor levels of artificial light were evaluated for Madrid and Barcelona, based on nocturnal images taken by astronauts aboard the International Space Station.

Aerial image of the city of Barcelona (Spain) taken by astronauts of the International Space Station. many sections of the city use mercury vapor lamps (orangish) but note the sections that are blue-whitish. CREDIT Image courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center.

Results obtained for both cities show that participants exposed to higher levels of blue light had a 1.5 and 2-fold higher risk of developing breast and prostate cancer, respectively, as compared to the less-exposed population.

Ariadna García, ISGlobal researcher and first author of the study, says: “Given the ubiquity of artificial light at night, determining whether it increases or not the risk of cancer is a public health issue”. At this point, further studies should include more individual data using for instance light sensors that allow measuring indoor light levels. It would also be important to do this kind of research in young people that extensively use blue light emitting screens”.

“Currently, the images taken by the astronauts on the Space Station are our only way of determining the colour of outdoor lighting at a large scale, and the spread of blue light-emitting white LEDs in our cities”, comments Alejandro Sánchez de Miguel, scientist at the Astrophysics Institute in Andalucía-CSIC and Exeter University.



Garcia-Saenz A., Sánchez de Miguel A., Espinosa A., Valentín A., Aragonés N., Llorca J., Amiano P., Martín Sánchez V., Guevara M., Capelo R., Tardón A., Peiró-Pérez R., Jiménez-Moleón JJ., Roca-Barceló A., Pérez-Gómez B., Dierssen-Sotos T., Fernández-Villa T., Moreno-Iribas C., Moreno V., García-Pérez J., Castaño-Vinyals G., Pollán M., Aubé M., Kogevinas M. Evaluating the association between artificial light-at-night exposure and breast and prostate cancer risk in Spain (MCC-Spain study). April 2018. DOI:10.1289/EHP1837. Environmental Health Perspectives

The full study is here:

I did some research into this.

There’s a Harvard study on night light, and in particular blue light.

But we may be paying a price for basking in all that light. At night, light throws the body’s biological clock—the circadian rhythm—out of whack. Sleep suffers. Worse, research shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity.

While light of any kind can suppress the secretion of melatonin, blue light at night does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).

In another study of blue light, researchers at the University of Toronto compared the melatonin levels of people exposed to bright indoor light who were wearing blue-light–blocking goggles to people exposed to regular dim light without wearing goggles. The fact that the levels of the hormone were about the same in the two groups strengthens the hypothesis that blue light is a potent suppressor of melatonin.

If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.


So it appears that a nighttime blue light component equals less sleep and therefore more stress on the body. With more stress, then susceptibility to cancer increases.

I don’t know how accurate the methodologies in these studies are, but one thing is for sure, many white LED’s tend to have a larger blue light component:

Comparison of “cool white” and “warm white” LED color spectrums. Source: EE stack Exchange

Have a look at the CREE guide to LED color mixing.

In cool white LED’s, the two colors (blue and yellow) mix to create a white. This is shown below on the CIE 1931 color space:

The mixed color (white) will be on a line between the two components (blue and yellow). The ratio of the intensities of blue:yellow determines the final color.


Note: about 15 minutes after publication, reference to the Harvard medical study was added.

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April 25, 2018 8:20 am

The study is not well designed. “Self reporting” is a big problem. And satellite images as a proxy for personal exposure? Really?

Reply to  M Simon
April 25, 2018 11:25 am

Exactly. And the length of exposure—6.5 hours—is as ridiculous as the claims of many common FDA-cleared food additives causing cancer because the quantity administered in the studies are impossible to replicate in the real world under normal operating circumstances.

Reply to  AZ1971
April 25, 2018 6:19 pm

I wonder if the 6.5 hours is including time spent in front of a laptop/tablet screen. I am probably hitting that. And staying up too late. And napping too much. So I am doomed.
Who is spending tons of time being exposed to green light?

Reply to  AZ1971
April 26, 2018 6:37 pm

Then they should discuss the backlights of smartphones, tablets, laptops… not just conventional lights.

Louis Hooffstetter
Reply to  AZ1971
April 28, 2018 8:08 pm

Is Michael Mann one of the authors? This paper ranks up there with his garbage. I believe this is the sad effect climatology has had on real science. In our world today, real news has been replaced by fake news, and now real science is being replaced by fake science.

Reply to  M Simon
April 25, 2018 1:40 pm

so staying up at night causes cancer, eh?
well, then- ask little rocket man for data on n. korea’s cancer free population.

Reply to  gnomish
April 25, 2018 3:59 pm

I hadn’t thought of that. A great control group if there ever was one.

Reply to  gnomish
April 27, 2018 6:09 am

Seriously, how could anyone survive night shift more than a week. They’d all be dead. Everything “causes” cancer as we’ve been told for generations now. Both studies are full of “may, might, could” weasel words.

Reply to  gnomish
April 28, 2018 10:08 pm

Revolution – that’s part of the problem. As an ex-Kalifornian, everything is shown to cause cancer. Your home, your place of work, where you shop, where you get gas, proximity to power lines, carrying a cell phone, red meat, sunlight, caves, brick houses, bananas, Brazil nuts, potatoes, carrots, lima beans, BEER… EVERYTHING! So why give a crap? Like my ancestors, i’ll take my meager 100 – 120 years and die. AND enjoy life.
Strangely, none of those ancestors died of cancer. Well, those on my mom’s side eschewed beer. Didn’t have cell phones. Maybe that’s what saved them. But as farmers, it was always “Bring on the red meat, baby!”

Zurab Abayev
Reply to  M Simon
April 25, 2018 2:49 pm

I agree with you

Reply to  Zurab Abayev
April 29, 2018 8:08 am

Zurab………………….I agree with you too !
It SEEMS as though …….anything that will muck up the dreadful Capitalist system…………………………
such as……….. STOPPING PEOPLE working at night ! Using a computer ! etc
MUST BE TRUE…………………………and if not…………….then let’s apply the CAUTIONARY PRINCIPLE
as the IPCC espouses ………………….and ” be on the safe side ” and stop it anyway !
The Socialists MUST be having a hard time finding support IF they are going to such lengths
LET’S HOPE SO anyway !

Reply to  M Simon
April 25, 2018 2:51 pm

Test all members of the study for serum Vitamin-D levels. Very low levels of Vitamin-D creates a significantly higher risk of such cancers. The body’s first—and main—line of defence against breast and prostate cancers is a high level of Vitamin-D. Taking Vitamin-D as a supplement doesn’t do much: get sun exposure.
The ‘Mediterranean life style confused everyone: it’s not the food, it’s the higher levels of solar exposure.
So: outside in the midday sun with your shirt off for half an hour (pale-faces) or an hour (max) for non-palefaces and make lots of Vitamin-D. Don’t use a sun-bed: UVA is useless, you need UVB.
The melanin deficiency of most Northern Europeans was to enable Vitamin-D production in low sun angle (low light) and cloudy conditions. The Nigerian coloring is the very opposite: it’s to protect against very strong and intense sun exposure. Seafood can be very rich in Vitamin-D.
Some sun exposure (UVB) is necessary for good health and cancer resistance. Over-exposure can damage and create what nature made Vitamin-D to cure.
Australia and New Zealand are the skin cancer capitals of the world with the highest incidences through over exposure but also the world’s highest survival rates, so maintaining Vitaman D is an mportant anti-cancer regimen. It also protects against coughs, colds and flus which always pass through a population at times of the year when vitamin D levels are at their lowest: late winter.
It’s more likely to not be LED wavelengths as an overall very low level of the human main anti-cancer protection: Vitamin D
“Vitamin D status at breast cancer diagnosis: correlation with tumor characteristics, disease outcome and genetic determinants of vitamin D insufficiency,” Hatse et al, Carcinogenesis 2012 May 24
“The association between breast cancer prognostic indicators and serum 25-OH vitamin D levels,” Peppone et al, Annals of Surgical Oncology 2012.
“Vitamin D deficiency in North America,” Hanley et al,
J. Nut. 2005;135:332-337.
:”Estimates of optimal Vitamin D status” Dawson-Hughes, et al
Osteoporosous Int, 2005;16:713-716
(it’s good for yer bones, too!)
“Sun exposure, vitamin D receptor gene polymorphisms, and risk of advanced prostate cancer,” John et al,
Cancer Res. 2005; 65(12):5470-5479.
A search in Google Scholar should turn up a lot more.

Reply to  sophocles
April 25, 2018 2:58 pm

Hmmmn. So, the the addition of the absence of blue rays under a sunny blue sky in Mediterranean climates does lead/does not lead to added cancers?

Reply to  sophocles
April 25, 2018 3:53 pm

That should be “participants in the study” not members and not the researchers—although knowing their own serum levels of vitamin D might be a useful for them.

Reply to  sophocles
April 25, 2018 4:02 pm

For UVB exposure follow the 50 degree rule. The sun must be above the horizon 50 degrees or you are not getting UVB. Both daily and seasonally. Where I live that means May to September and 11 AM to 3 PM.

Reply to  sophocles
April 25, 2018 7:07 pm

Aus an Aussie who’s visited other parts of the world I’d say Aussies tend to be a lot more sun-shy than folks may think. Go to any outback area and you’ll see some of the palest individuals you’ll ever see as we scurry from wide verandah to verandah, covered in long sleeves and broad rimmed hats.. and there’s a reason for that, in the words of the great Ozzy Osbourne after a stop in Perth allowed him to get some sunshine ..”Well, I’ll just grab a bit of a suntan’. I sat on this wall for about 20 minutes and I was fried. I had to spend 30 hours on a plane on fire. “I don’t lie in the sun anymore because that frightened the crap out of me”
it can sting a bit being exposed to sunlight under the Australian sky

Reply to  sophocles
April 26, 2018 4:27 am

Vitamin D also helps MS. sufferers.

Reply to  M Simon
April 26, 2018 5:45 am

“The study is not well designed.” – I love the understatement.
Not well designed = total crap we made up to support our preconceived notions.

Eustace Cranch
April 25, 2018 8:22 am

Read this with great skepticism…trying to imagine what the biological mechanism would be. Is it from skin exposure? Or is it from some sort of body response to optical exposure? In that case, would a blind person be immune?

Reply to  Eustace Cranch
April 25, 2018 8:25 am

agreed – I hate the blue lights, much too harsh, but I don’t want to buy into the post-science statistical methods used here.

Reply to  wws
April 25, 2018 9:44 am

I conducted a study of my own. It seems as though the very LAST string of outdoor Christmas lights at my local (national chain) hardware store was an energy-saving string of LED’s … not what I wanted, but beggars can’t be choosers. So I took them home, hurriedly put them on my house, set the timer, and never gave it another thought. Till my adult kids came home for Christmas and asked me what the HELL had I done to our usually festive outdoor decorations!!! Our house was a sickly shade of light blue!!! Then … the neighbor comments came. Welllll, they tactfully said … your lights are … uh … different this year. I didn’t wait till New Years Day, but stripped the lights off my house and tossed them in the trash. They were a CANCER to my familial and neighborly relationships.
Yes, I know that the “temperature” of LED’s makes all the difference … perhaps a string of 2,700 deg. lamps would have been more palatable. But … nevertheless … I have gone back to the ol’ planet-wrecking incandescents. Nothing says “Celebrate Jesus birth” like some planet-wrecking incandescent lights on a bible-thumpers (denier’s) SINGLE family home… eh… planet protectors?
[The mods trust that the WUWT community will recognize the lighthearted nature of this poster, and will not attempt to derail the topic into discussions regarding religion. Your indulgence (pun intended) in this matter is greatly appreciated. -mod]

Reply to  wws
April 25, 2018 10:51 am

Isn’t there a song about a blues Christmas?

Reply to  wws
April 25, 2018 1:34 pm

Thank you moderator … for the proper treatment of my lighthearted post that failed to carry a {sarc.} tag.
I meant no disrespect to any religion, creed, or birthright. Esp. my Jewish friends who display blue lights at Hanukah. No .. my disrespect is directed squarely between the eyes of each and every know-it-all, nanny Statist bureaucrat who has removed incandescent lights from the shelves of the free marketplace. Every Marxist, Socialist, and outright card-carrying Communist who shoves their social science and manipulation down my gullet. I DO use LED’s … in ways of MY choosing. Not in response to some 1st world guilt complex.

Louis Hooffstetter
Reply to  wws
April 28, 2018 8:16 pm

HotScot: Here you go:

Steven F
Reply to  Eustace Cranch
April 25, 2018 9:28 am

I guess we all should not go outside. Blue light levels outside at noon are many orders of magnitude brighter than what is present inside at night.

Lonny Eachus
Reply to  Eustace Cranch
April 25, 2018 9:50 am

Likely the culprit they point to (or imagine) is melatonin.
For example, this is a problem in the domestic ferret, which is a crepuscular animal. That is, normally in the wild it is active around dawn and dusk, and sleeps much of the day in a dark burrow.
However, in domestic situations, people often keep ferrets indoors in a cage with no cover, and no dark place to sleep during the day. This disruption of the light-dark cycle messes with the normal release of melatonin, which in turn alters the release of other hormones.
While this may not sound like a big deal, research has shown that this light-dark cycle disruption contributes to “adrenal disease” in ferrets, which is a growth of tumors on the adrenal glands. These tumors can and often do become malignant.
I suspect the researchers are looking for a similar connection.

Janet L Chennault
Reply to  Lonny Eachus
April 25, 2018 1:03 pm

Thank you for that bit of technical knowledge that most of us would not be aware of. I think that melatonin is also likely to be key.
One must also remember that a survey is not an experiment; it is one of the sources of inspiration from which an experiment can be devised.

Reply to  Lonny Eachus
April 25, 2018 3:59 pm

If it’s related to melatonin then there will probably be an association with non-24 syndrome among blind people, should be possible to check that.

Reply to  Eustace Cranch
April 25, 2018 9:51 am

we’ve more sensors that respond to various wavelengths than just our eyes, melanocytes in our skin absorb near blue UV to produce Vitamin (hormone actually) D – maybe the breakdown products in the biochemical pathways generate byproducts that instigate secondary action.. don’t know, wouldn’t rule it out.
Of course that’s just one known chromatophore, who knows what other ones we have – we keep finding organs and organelles that have been overlooked and discovering hey – these things do stuff!
I mean who’s aware that we have IR sensors as sensitive if not more so than a pit vipers across various parts of our bodies including our upper lip – do we use them? not consciously- but then we don’t even use our eyes consciously despite being aware what they do. Could other sensors be productive not just in a neural sense but in a biochemical sense? Heck we didn’t even know our eyes were used biochemically until recently in making hormones. ore research needed, research I’d support, not just to counter or support a health scare but rather to learn more about ourselves and the things that make us tick.

Reply to  Karlos51
April 25, 2018 10:53 am

Every day’s a school-day.
Unless of course you’re a concencus climate scientist who can’t possibly learn any more.
In other words, they’re full of it.

Eustace Cranch
Reply to  Karlos51
April 25, 2018 12:09 pm

But sunlight from a clear sky has enormous amounts of blue light. Do people who work outdoors have elevated instances of breast and prostate cancer?

Reply to  Karlos51
April 25, 2018 7:19 pm

Eustace Cranch sunlight from a clear sky has enormous amounts of blue light..
sure, but circadian rhythms and melatonin and so forth – quoting wikipedia which closely resembles material read elsewhere: “In vertebrates, melatonin is produced in darkness, thus usually at night, by the pineal gland, a small endocrine gland located in the center of the brain… Light/dark information reaches the suprachiasmatic nuclei from retinal photosensitive ganglion cells of the eyes”..
stuff at the ‘right time’ good, stuff at the ‘wrong time’ .. not so good. I don’t buy into it being causal of cancers – as others have said – show me the pathways – but I’m also open to learning and hearing more.
But how about red light though, that has some interesting properties when you go looking into it’s purported healing qualities despite there being little explanation as to why it may work
I’d like to hear more about both to be honest but we’re unlikely to do so unless research can discover pathways.

Reply to  Karlos51
April 25, 2018 9:20 pm

If you research the well-established link between shift work and cancer, especially breast cancer, I think you’ll find the pathways are somewhat well worked out and relate to disrupted melatonin

Reply to  Karlos51
April 25, 2018 10:38 pm

I think the main problem I have with this study, and many in the cancer field, is that it confuses ’causes cancer’ with ‘reduces the body’s ability to prevent and fight cancer’.
I highly doubt that the amount of blue light we are exposed to at night from LED’s compared to from any other sources could ’cause’ cancer, especially prostate cancer. (At least I know MY prostate isn’t getting exposed to much of it) but from what I know of Melatonin production, circadian rhythm, and related, it would make sense that exposure to a lot of blue light at night could inhibit the bodies ability to RESIST the formation of cancer cells and tumors.
It certainly is a field that is worth researching, but one needs to be aware that it is just as susceptible to the kinds of research puffing ( publish or perish, science by press release, bias, etc) as any other science.

Reply to  Karlos51
April 26, 2018 8:23 am

“I think the main problem I have with this study, and many in the cancer field, is that it confuses ’causes cancer’ with ‘reduces the body’s ability to prevent and fight cancer’.”
The problem with this statement is that from a practical standpoint, from what I know of cancer, the “ability to prevent” is by far more important than reducing causes since all external triggers for cancer could be removed and normal cellular damage could still trigger cancer if the body’s various mechanisms (e.g. the immune system) for preventing cancer are weakened. This is apparently partly why Vitamin D level reduce some cancers but also strengthen the immune system.
Most importantly, there are clear actions to reduce circadian disruption that from cost/benefit risk/reward standpoint everyone reading this should be doing such as using f.lux, blue-blocking sunglasses for night computer work, supplementing melatonin when necessary, and using yellow light in their evening workplace. See Kent Noonan’s comments below. Paul Jaminet has written extensively about circadian entrainment. Health, like most other things in life is not about certainties, but about probabilities and taking easy, no risk/cost steps that may help is what those of us focused on optimal health do. We will not have perfect science to answer these questions in the timeframe which we need to make decisions, so we need to act on what we do know.

Reply to  Eustace Cranch
April 25, 2018 10:58 am

“trying to imagine what the biological mechanism would be.”
Exactly. They think they have found a correlation. Fine. Next step, come up with a biological mechanism to explain it. None proposed. So this is just another one of a gazillion quirky correlations.
But someone will publish it.

Reply to  Eustace Cranch
April 25, 2018 12:06 pm

Is there a problem if people sleep under blue light? Or, is it just that they choose to be awake at night, and BTW, blue light helps keep them awake and alert? I’d need to see a lot more research before I got all hot and bothered by this. Then I could swap my blue LEDS for red LEDs, or are you going to tell me they’re bad also?

John Garrett
April 25, 2018 8:22 am

Somebody’s got too damn much money and time on their hands.

Reply to  John Garrett
April 25, 2018 10:45 am

Apparently so!

Chris Hebert
April 25, 2018 8:32 am

You can correlate almost any two things. Great site: There is a very high correlation between per capita cheese consumption and number of people who died by being tangled in their bed sheets, for example. Correlation doesn’t equal causation.

AGW is not Science
Reply to  Chris Hebert
April 25, 2018 9:14 am

Current CO2 level vs. temperature being the classic example!

Dr K.A. Rodgers
Reply to  Chris Hebert
April 25, 2018 9:36 am

100% of those who drink water dies.

Reply to  Dr K.A. Rodgers
April 25, 2018 9:47 am

NOT True!!! All the soccer moms who have water bottles permanently attached to their hands … told me that “drinking 8 glasses of water per day” … will … SAVE THEIR LIVES!!!!

Ken Mitchell
April 25, 2018 8:33 am

I wouldn’t put a whole lot of faith in the “association” between white LEDs and cancers. The bit about melatonin production being affected by whitish light is fairly well known; notice the software programs that will turn your video display screens more reddish in the evening. Things like “f.lux” for Windoze, or “Night Shift” on Apple devices, or “Blue Shade” for Kindles or “twilight” in Android devices. I use them, and I do sleep better than I used to.
Perhaps there’s some as-yet-unknown mechanisms by which lower melatonin production might increase the risk of some cancers – but I sort of doubt it.

Reply to  Ken Mitchell
April 26, 2018 3:30 am

i was about to mention f.lux
i DO find the shaded screen restful compared to the harsher white/blue normal screen at night.
i buy only the incandescent yellow normal lightbulbs they dont last as long maybe but at least i can see and read, with those cruddy curly things i can hardly see the edges of the room

April 25, 2018 8:38 am

Correlation does not prove causation and p-hacking is not a scientific method.

April 25, 2018 8:43 am

Warm white LEDs do not have more blue content in their spectrum than incandescents and warm color fluorescents do. Yet nobody is accusing incandescents or the blue light from fluorescents of causing cancer.

Reply to  Anthony Watts
April 25, 2018 9:51 am

Putting my foot in my mouth? Did I not say the *blue light* from fluorescents? You responded by bringing up ultraviolet.

Joe Kbetcha
Reply to  Anthony Watts
April 25, 2018 10:29 am

And the original article caption for the satellite shots confuses Hg vapor with Na vapor color spectrums. Totally bogus, of course. Which puts the entire article in doubt.

Mike McMillan
Reply to  Anthony Watts
April 25, 2018 9:47 pm

I noticed that about the Barcelona street lights, too. Those might also be the multi-vapor lights, since cameras don’t record light colors the way our eyes do.
We had a white plastic thermometer on the wall in my brother’s basement about 4 ft from a curly cfl. After a year, the white had turned tan where the cfl uv was hitting it, but the back and far side were still white. I replaced the thermometer with a new white one, and sprayed the cfl with Krylon Archival UV varnish. That cured the uv completely.

Phil Rae
Reply to  Anthony Watts
April 26, 2018 7:44 am

Actually, the NHI paper cited shows no statistical increase in the incidence of malignancy with regular fluorescent lamps but does show the danger of ultraviolet tanning lamps and sun beds. So, from what I can see, there is no specific cancer risk from the light emitted by regular or curlycue fluorescents assuming their phosphor coating is intact.

April 25, 2018 8:44 am

Study links night exposure to blue light with breast and prostate cancer

Goes to show you should not expose your breast or gonads to outdoor night blue light. What are they thinking?

Reply to  Javier
April 26, 2018 3:17 am

Why do you think that anybody related to this study actually thinks?

April 25, 2018 8:47 am

“Mays”,,. “mights” and other ‘hypotheses’ without testing, validation or verification. Pseudo-Science perfectly ready for publication in the Scientific American to scare people without regard to falsification. There should be a new ‘social science’ called ‘scare science’. It’s proven to be very productive in generating a lot of $$$ in grants and the grantees with bonus’s of more $$ for publishing articles and commentary in the popular media.

April 25, 2018 8:47 am

LED lighting is similar to fluorescent lighting. A phosphor is excited by a short wavelength and emits longer wavelengths. link
Fluorescent bulbs may emit a bit of ultraviolet and that can pose a risk. link Even then you have to be pretty close to the bulb. Most of the UV doesn’t make it out of the bulb.
The problem with LED lighting is that the blue light does make it out of the bulb. It’s needed to excite the phosphor and it’s part of the desired light. You could get rid of the blue light with a filter. That, however, would reduce the bulb’s efficiency a lot. It’s kind of a Catch 22.
The biggest problem with blue light is that it prevents people from getting sleep. link That probably does cause health problems.

Lance Wallace
April 25, 2018 8:55 am

The strongest association (odds ratio 2.8) was for persons with highly illuminated bedrooms. (subjective measure). Blue light not broken out by this measure.
The blue light effects are from outdoor measures. But people spend on average 6% of their time outdoors (1.5 hours). So for this to have an effect, it would have to be mighty powerful. But no mention of determining the amount of time spent outdoors could be found. A major flaw. If they found that time spent outdoors exposed to blue light was still (or perhaps more) significant, their findings would be slightly more believable. As it is, my money would be on this result adding to the great number of nonreproducible results in peer-reviewed articles.

Reply to  Lance Wallace
April 25, 2018 9:38 pm

If there was an effect it would be easy to see as the outside blue value would vary by something like 20 fold from arctic to texas.

April 25, 2018 8:59 am

“There is evidence pointing to an association between exposure to artificial light at night, disruption of the circadian rhythm, and breast and prostate cancers”

A curiosity becomes a pointer, becomes correlation, becomes causation.
N.B. This is the same IARC that fudged glyphosate results to produce their specious “Cancer causing” results.
Trust these not at all.

Reply to  ATheoK
April 25, 2018 2:10 pm

Thanks for the reminder.
I think very little of studies like this fron known corrupt orgs.

April 25, 2018 9:01 am

in a sister study….
Scientists discover whoring around late at night leads to an increase in breast and prostate cancers….
……film at 11

Reply to  Latitude
April 25, 2018 9:32 am

Also, apparently women who have been drinking are more fun to study:

April 25, 2018 9:04 am

Maybe check out California and there LED streetlights some more to broaden the article?

Johan Meijer
April 25, 2018 9:05 am

Do my 3000K led bulbs put out a lot of blue light? The light looks yellow enough. Is this only a matter of color spectrum of the light?

Steven F
Reply to  Johan Meijer
April 25, 2018 9:35 am

The higher the K number the higher the amount of blue. Daylight bulbs typically have a K rating of 5000k. 3000K is a lot less. 2700K or soft white puts out almost no blue (over 90% is blocked by the phosphor). All bulbs incandescent, fluorescent and LED put out blue light at about 460nm.

April 25, 2018 9:10 am

Breaking News!!!! Study shows that being alive increases the chances of death by 100%
In other news: Study shows that repeatedly being bashed with junk science “studies” increases the chances of chronic cynicism by 75%

April 25, 2018 9:14 am

Another fake “clinical research” article suffering from dissociative cognizance of association is causality belief, even if the findings were at p<0.00001.
If blue light was causing circadian rhythm disturbances without compensation, all marine vertebrata with color vision would have been extinct by now.

April 25, 2018 9:22 am

Reading small phone/tablet and laptop screens all the time, especially late at night under the blue light, will also cause near sighted vision and over extended time frames, physical damage to the eye anatomy. After awhile, as most could probably concur, it feels like daggers in your eyes after extended hours of reading and browsing the internet especially after a long day. But then, reading small print such as the Bible under candle light for extended periods will also cause similar near vision as generations of our ancestors could attest to.

Reply to  Earthling2
April 25, 2018 12:07 pm

I must wear blue blockers when using the computer or watching TV. If I don’t my eyes burn and itch like crazy.

April 25, 2018 9:25 am

Blue light eh? So much for going out to enjoy sunshine.

Bill Illis
Reply to  John
April 25, 2018 10:19 am

There is all this blue sky out there giving us cancer.

Reply to  John
April 25, 2018 7:27 pm

a small point about the sky I’d like to add – it’s been suggested it’s not blue but cyan 😉
Bung an optical minus blue filter over a lens and you’ll notice the sky does not darken as considerably as one would expect, bang a minus cyan filter over your lens and the sky appears black as the cyan blocked leaves little else in the spectrum.
I really am curious about the blue light claims though – more from an academic perspective than hype of ‘oh noes cancer because, science’

April 25, 2018 9:28 am

I have doubts about the cancer connection, but blue light is definitely annoying to me, especially at night. The blue car headlights often seen nowadays are dangerous (blinding) at night IMO.

Reply to  beng135
April 25, 2018 10:01 am

The blinding blue LED headlights are great, if you are the one driving with them. But, if you blind the oncoming traffic and they head on crash into you, I don’t see much benefit unless you want to die. I don’t know how those things are legal, especially in high beam mode. Definitely a huge liability, especially driving in snow and ice when reflection is amplified. Literally blind for those few seconds while passing, and if a convey of semi trucks are approaching one after another on a two lane road with these blue LED’s, you are essentially blind for that duration. I wear a pair of sunglasses on my head that I can drop so as I can try and stay on the road, but essentially now, I try not to drive at night because of this. How did the DOT make these things legal?

Reply to  Earthling2
April 25, 2018 10:13 am

You’re right about the DOT — most ANYONE knows red light is less strenuous on your night-vision. Yellow headlights (as they had always been in the past) are acceptable, tho even those might be “reddened” slightly to lessen effects on oncoming drivers. Blue headlights go in the WRONG direction.

Reply to  Earthling2
April 25, 2018 2:16 pm

France used to, and still may, use yellow lights for auto night driving.

Reply to  Earthling2
April 25, 2018 5:07 pm

The headlights are terrible if they are behind you. I once drove for a few miles with those things shining into my rearview mirror. I was trying to slouch or sit really straight to avoid the reflection, but no such luck. I actually had trouble seeing in front of me because of the way the light was shining and reflecting – even though it was coming from BEHIND me.
I was about ready to pull over onto the non-existent shoulder and let the car pass, when he finally turned onto another road.

Reply to  Earthling2
April 25, 2018 7:48 pm

Wear amber driving/shooting glasses. Improves vision with or without the LED lights.

Reply to  Earthling2
April 26, 2018 4:51 pm

Oh, I am so with you on those damned blue headlights! They are a definite hazard for oncoming drivers.

David LM2
April 25, 2018 9:29 am

Guess I’ll have to hang out in the red light district instead.

April 25, 2018 9:38 am

“It would also be important to do this kind of research in young people that extensively use blue light emitting screens”
I thought screens emitted whatever color was in the image being displayed?

April 25, 2018 9:50 am

IARC = junk science. They also believe themselves to be above any criticism or even inquiry.
With respect to the referenced study, it has just about everything wrong with it methodologically. But you need go no further than the subjects enrolled in the study were aged 20 to 85… that is born as early as in the 1920s! And they think we should buy a correlation of cancers with often long development times to a snapshot of light taken from space in 2012?

April 25, 2018 9:57 am

Reader’s Digest version …… everything associated with humans is bad for humans. Get over it. You’re a pox on humanity until you die.

Kent Noonan
April 25, 2018 10:02 am

I work with light a lot, lasers and LEDs, and I have studied extensively the biological effects. The entire subject is much more complicated than what is presented here. There are numerous mechanisms where light is known to influence human physiology, both good and bad effects. The spectrum of various light sources vary enormously, even lights that look similar to the eye. Some, like fluorescent, have a very large spike in the blue spectrum balanced by low energy broad range of red and yellow. Some of the modern LEDs have a spectrum almost indistinguishable from solar. Some LEDs have a spectrum almost the same as fluorescent. If it appears bluish-white, it has too much blue.
Biological effects of light are well documented: ATP production increase, melatonin decrease, catalase and SOD suppression, nitric oxide, cytokines, immune function, influences on fertility, cancer, bone growth, wound healing, brain function, alzheimers, burn healing, macular degeneration, a very long list. If you doubt it, go to pubmed and search.
Can blue light cause cancer? Maybe. Anything that throws the regulatory system out of whack could possibly do that. Catalase and SOD in particular could be a bad influence. Blue light certainly alters stress response and sleep patterns. I agree that measuring blue light from space is a bad idea, since it doesn’t reflect well off typical urban surfaces.
However, there are strong influences not considered here. Most people don’t get nearly enough UV light, needed to produce vitamin D and melanin. We are constantly told to use sunscreen and wear UV blocking glasses. This probably causes more cancer than blue light LEDs, as well as suppressing immune function for more common diseases.
So be doubtful and ignorant about blue light if you want. If you really care, study the science. I use f.lux or isis programs to turn down blue light on my computers, and I use UV and infrared light every day to promote health. I found good LED lights from “Greenlite” brand, cheap at Ace Hardware, nearly the same as solar. Rely on natural light as much as is convenient, get some sun, avoid staying up too late and sleeping during the day. Some facts and common sense could change your life.

Reply to  Kent Noonan
April 25, 2018 10:28 am

At my age just pour another G & T and relax. The damage is already done and you are living with it.

Kent Noonan
Reply to  Leo Smith
April 25, 2018 10:34 am

I think G&T comes under the common sense category. And bending your elbow does count as exercise.

Kent Noonan
Reply to  Leo Smith
April 25, 2018 11:57 am

I would add that you don’t have to resign to living with it. You can use infrared light to feel much better. 750-900nm light penetrates tissue well, relieves inflammation, promotes healing. Even in us old guys. I’m in my 60s and feel as good as 40s most of the time. I have an old injury in shoulder that makes it useless if I don’t use infrared. My older brother uses it for arthritis, better results than Rx. And it has been shown in studies to reduce alzheimers symptoms in about 80% of cases. Most returned to fairly normal life after treatment. It has even been shown to improve outcomes in heart attack and stroke.
Search pubmed for “LLLT OR photobiomodulation” plus condition, thousands of studies.

Reply to  Kent Noonan
April 25, 2018 10:36 am

Thank you Kent. And Vitamin D could be thrown off by wireless technology by interfering with the VDR Receptor: I doubt the issue of health effects from non-ionizing radiation will be popular to post about though – the good or the bad in it. I too use blue light goggles towards evening and try to get out in the sun to keep my clock “on”.

Christopher Paino
April 25, 2018 10:03 am

Well, astronomers will be very happy with this “study”. They hate those confounded LEDs ’cause they block out the stars. Maybe this is an attempt to link the lights to cancer so that they can have a reason to get rid of them? Prolly not, but who really knows?

Ralph Knapp
April 25, 2018 10:07 am

Yet another GIGO ( garbage in, garbage out} computer model reported as fact.

April 25, 2018 10:09 am

My prostate has never seen the light of day, nor has my bile duct – until my cancer surgery.

April 25, 2018 10:26 am

If there were a CO2 angle in this study it would be about baby animals like polar bears or baby deer.

April 25, 2018 10:28 am

So maybe we would be better off if all forms of artificial lighting were banned. Certainly banning all forms of artificial lighting would help to reduce carbon pollution from the burning of fossil fuels.

Nigel S
April 25, 2018 10:38 am

From the early, early mornin’ till the early, early night
You can see miss Molly rockin’ at the house of blue light.
Good golly, miss Molly, sure like to ball.
When you’re rockin’ and a rollin’ can’t hear your momma call.

Robert of Ottawa
April 25, 2018 10:44 am

Just nonsense. The positives far outweigh the negatives. If I were Spanish, I would sell my shares in La Caixa for funding this study. Obviously they’ve been captured by fear-mongers.
And if it does at all bother you, wear a hat or live in the dark.

April 25, 2018 10:51 am

I’m not sure any of this matters. Remember how power lines were bad until we needed a million miles of them for wind and solar? Anything can go from bad to irrelevant in a heartbeat if it suits the current storyline.

April 25, 2018 11:09 am

‘Results obtained for both cities show that participants exposed to higher levels of blue light had a 1.5 and 2-fold higher risk of developing breast and prostate cancer, respectively, as compared to the less-exposed population.’
Note the hyped math: ‘2-fold higher risk’ in a small population. Easily explained as noise. Beware any study that says higher risk without giving actual numbers, from X to Y. 2x tells us nothing.
The cynic in me says they have bottomed out. They publish this because they have no path forward. If they had a path forward, they’d keep working on it til they had better data, and a real story to tell.

Tom in Florida
April 25, 2018 11:23 am

The Harvard study says:” At night, light throws the body’s biological clock—the circadian rhythm—out of whack. Sleep suffers.”
Apparently several pints at your favorite pub can counteract the disruption of your biological clock due to light. Perhaps a nice grant to study this would be appropriate. Who wants to volunteer?

Paul Penrose
April 25, 2018 11:52 am

Whenever I see something say “x is linked to y”, I know it is meaningless. The word “linked” has no scientific meaning and is only used when the results are so weak they can’t even say with the straight face that the two things are correlated, let alone claim causation.

Joel Snider
April 25, 2018 11:58 am

Remember – no consequence is too great to save the planet – particularly if it also helps weed out those hominid despoilers.
Whether this cancer-link has any legitimacy or not is almost irrelevant – what’s ironic is how this sort of thing will be brushed over, while the slightest concern involving any targeted power source is sufficient to shut down entire industries.
The sort of ‘concern’ that one wears on their sleeve.

April 25, 2018 12:26 pm

I just could not read the article, because the premise of isolating blue light (apart from all other factors) as a cause of cancer seemed too far fetched — to the point of being absurd.
Am I being too hasty, or did anybody else have this immediate first impression?

Bruce Robertson
April 25, 2018 12:38 pm

I’d like to see a study includes actual measurements of subjects’ estrogen and testosterone levels, hormones that do feed breast and prostate cancers. If blue light down regulates melatonin, might there be an offsetting up regulation of these sex hormones?

NZ Willy
April 25, 2018 12:42 pm

Silly to blame the LED light when it’s the unnatural night-time work causing the stress.

Reply to  NZ Willy
April 25, 2018 2:10 pm

The average age of the women in the study with breast cancer was 55.8 (s.d. 11.9). For the men with prostate cancer it was 65.1 (s.d. 6.8). Note that this was their age at the time they were interviewed for their exposure histories, NOT their age at first diagnosis.
So it’s also silly to blame LED when a large number of these people first developed cancer long before they ever saw their first LED light bulb of any kind, never mind significant amounts of LED outdoor lighting.
Final note: participants over 40 years of age were asked to estimate their indoor, nighttime exposure level at age 40. For many of them that would have been 30 or 40 years prior. The Likert scale categories were: total darkness; almost dark; dim light and quite illuminated. The study further states that no further definition of these categories was provided. That’s a pretty good leap from “dim” to “quite illuminated.” It seems likely to have biased the numbers toward the highest category.

Walter Sobchak
April 25, 2018 1:23 pm

You realize that manufacturers of LEDs can alter the LED’s emissions spectrum, don’t you.

April 25, 2018 1:31 pm

Wow, the most cynical comment thread ever! lol

April 25, 2018 1:53 pm

Flashing blue lights in my rear view mirror causes a spike in my heart rate and blood pressure as well as anxiety.

April 25, 2018 1:57 pm

On a more serious note. The old ‘yellowish’ street lights of 50 years ago attracted swarms of insects that attracted bats. The lights changed and the bugs and bats disappeared.

April 25, 2018 1:58 pm

That is another reason I still have a house full of incandescent lights. Threw all my CFL lights out years ago when one exploded in the washroom, and never even went for the LED .

Moderately Cross of East Anglia
April 25, 2018 2:18 pm

Please keep up this particular scare – when the ghastly eco bulbs were forced in by legislation in the U.K. I bought several hundred incandescent tungsten bulbs for a few pounds on the last day shops were still allowed to sell them. I still have a large stock and look forward to selling some at senseless and extortionate prices if people become terrified of contracting cancer from LEDs.
Sound cynical ? I suppose so but small beer compared to the much more cynical climate terrorism visited on us all.

Reply to  Moderately Cross of East Anglia
April 25, 2018 6:12 pm

I remember going to Target shortly before the (effective) ban on traditional incandescents and loading up on light bulbs. There was another man in the aisle doing the same thing. I wish I could remember his exact comment, but it was something to the effect of “thanks a lot, damn light commies”. (In a suburb of D.C.!)
There were no more old-school incandescent bulbs left when we walked away from that aisle. And I was very sad when I finally ran out of those bulbs and had to shell out a small fortune for the lower quality “eco-friendly” bulbs.

John in Oz
April 25, 2018 2:26 pm

Are the observed effects due to higher blue light levels OR lower red/green light levels?

Reply to  John in Oz
April 26, 2018 12:26 am

Are they even observations at all, or just made up stuff like the glysophate “study”?

John Brisbin
April 25, 2018 2:27 pm

Amusing that the ‘NASA’ caption indicates “many sections of the city use mercury vapor lamps (orangish)” which is obviously false. Mercury vapor lamps have a strong blue and UV component. They provide a better light quality due to their diversity of spectrum but are less efficient in ’empty’ lumens that sodium lamps that provide the orange, nearly monochromatic, light seen in the photo.
Finally, I note that if blue light encourages drivers to wakefulness, I consider that a win. Also, If you work at night, optimizing the circadian rhythm for a night active schedule is a good thing for work performance, injury reduction and personal well-being.

April 25, 2018 7:05 pm

All the filament LEDs I’ve seen to date emit a warm yellow-biased light, not unlike an incandescent.×448.jpg
But you can’t make plasma in the microwave with an LED.

April 25, 2018 8:02 pm

“We know that depending on its intensity and wave length, artificial light, particularly in the blue spectrum, can decrease melatonin production and secretion”

But not as much as actual darkness. Go outside. During the day.
Its not “blue light” that stops people from doing that! And for the “researchers” stop doing “research” that finds correlations and expects causation based on what they want to show (ie the blue light change part) whilst apparently ignoring behavioural change.

April 25, 2018 8:29 pm

I imagine we can come up with any number of increasing independent variables that correlate with one thing or another. It’s this rush to cause-effect assignment that is responsible for a lot of junk science and superstitions.
Show me the controlled experiments

Mike Smith
April 25, 2018 9:44 pm

So which is worse? The cancers resulting from exposure to LED lighting, or the cancers resulting from the combustion of fossil fuels to power incandescent or other less efficient forms of lighting?
I’m sure one of these geniuses can develop a computer model…

Ed Zuiderwijk
April 25, 2018 10:52 pm

Confounding factors.
Elementary statistical techniques, look it up under confounding factors. Where do you find those blue lights? In cities. Where do environmental causes of some cancers concentrate. In cities.
Where do you find the blue lights? In cities. Where do you find cinemas? In cities. Therefore those lights must have something to do with movies.
Utter nonsense.

Reply to  Ed Zuiderwijk
April 27, 2018 4:33 pm

“Where do environmental causes of some cancers concentrate”
Which ones? The contraceptive pill? Hormone substitution treatment?
Infrequent ejaculations?

April 26, 2018 12:21 am

The key for me is that the group behind this claim was caught fabricating evidence to support another so-called study claiming glysophate, a weed killer, causes cancer.
And then lied and stone walled about it.
Also, deciding that blue light is a “likely” carcinogen based on the poor quality evidence of the report discussed in this blog post implies strongly that the decision was made prior to the study. The evidence offered is barely coincidental, much less linking in a causative manner.

Reply to  hunter
April 27, 2018 4:34 pm

I guess any herbicide is going to be statistically linked with almost any other legal pesticide and all types of cancer known to be higher in agricultural regions.

Dr. Strangelove
April 26, 2018 4:53 am

UV light is proven carcinogenic and girls like UV tanning

Tom Schaefer
April 26, 2018 5:13 am

I’d like to point out that LED lighting can be modulated in frequencies that are not noticeable to alter mood and attitude. There will come a time when wise people will install a low-pass filter on the power coming into them. If you think this is beyond the nefarious thinking of the Deep State and their controllers, you are badly mistaken.

April 26, 2018 5:18 am

Correlation, linked to superstitious thinking.

April 26, 2018 6:48 am

International Agency for Research on Cancer (IARC),
have declared that virtually EVERY item / substance
they have ever tested causes cancer —
causes cancer — I think there was one exception:
The French International Agency
for Research on Cancer (IARC)
received over $48 million
from America’s National Institutes of Health (NIH).
They have “tested” over 900 chemicals,
and 899 were claimed to be carcinogenic !
Complete nonsense!
IARC must be ignored and should not be partially funded
by NIH !

Reply to  Richard Greene
April 26, 2018 6:10 pm

French of IARC is CIRC, pronounced cirque (circus).
Dissolve the IARC, WHO and CDC!

April 26, 2018 11:45 am

Regardless of cancer. These lights have killed my sky watching nights to zero. So much light pollution that even with a 12 dobsonian I can’t see anything!

April 26, 2018 5:26 pm

Why isn’t the massive breast cancer screening program even discussed? They know the bigger number in “cancer” (tumors) is caused by cancer screening, right?

April 26, 2018 9:59 pm

I can’t stand yellow light. I call it jaundiced, it almost makes me nauseous. If a monitor is too “warm” at “cool” settings I will dispose of it.
Am I an alien or am I just doomed to all the ailments blue light is supposed to cause?
Or is all this just a consequence of generic internet hysteria?

April 28, 2018 3:34 am

Breathing air may be giving us cancer.
Drinking water may be giving us cancer.
We should probably stop doing both, We will die, but we won’t get cancer.

The Third EYE
April 30, 2018 3:30 pm

The New LED lights were designed to make you unhealthy look up the companies behind them you will find the Rockefellers. this has been well documented.
Stay away from them the Light Bulbs are harmful!

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