blue light associated with prostate and breast cancer


In general, warmer color temps emit less blue wavelength versus cooler color temps. Also high CRI and R9 lights in general, to a lesser extent, emits less blue wavelength because the thicker phosphor converts more of the base blue light into other wavelengths to create warmer and higher CRI light, which allows less blue light to escape unconverted. The blue wavelengths that did not get converted through the phosphor are the “potentially” health concerning portion of the light.

For example, comparing 4000K XP-L HI 70CRI vs 4000K SST-20 95CRI, the XP-L HI produces (visually estimated from spectral graph) 20% more blue light with a much taller blue peak. I have been doing a lot of testing with my spectrometer lately so the above generalization is true for “most” cases however I find sometimes HI CRI of same CCT can produce more blue light than lower CRI of the same CCT. Also I’ve seen lights measuring the same color temp and similar CRI can vary significantly in the amount of blue intensity. So without testing the specific emitter, the above generalization is not an absolute rule.

I’m glad somebody is paying attention to the science.

Chronobiol Int. 2012 Jun;29(5):641-9. doi: 10.3109/07420528.2012.675850.
Assessment of a new dynamic light regimen in a nuclear power control room without windows on quickly rotating shiftworkers—effects on health, wakefulness, and circadian alignment: a pilot study.

Keeping nuclear power plant night shift operators alert — it’s a good idea.
Who designed the original windowless dimly lit control room?

The American Optometric Association has also commented on the above-mentioned Spanish study:

And on other research on the direct photochemistry (this is energy delivered by the high energy blue photons directly to the retina, unrelated to the melatonin/cancer issue)

I noticed my eye doctor no longer uses a blue examination light for a long period of time when looking at my retinas, instead they use a yellow light that briefly changes to blue. I read of a couple of cases of blindness where a blue examining light was mistakenly left on too long.

More research
PLoS One. 2018; 13(3): e0194218.
Published online 2018 Mar 15. doi: 10.1371/journal.pone.0194218
PMCID: PMC5854379
PMID: 29543853
Removal of the blue component of light significantly decreases retinal damage after high intensity exposure

Int J Ophthalmol. 2018; 11(12): 1999–2003.
Published online 2018 Dec 18. doi: 10.18240/ijo.2018.12.20
PMCID: PMC6288536
PMID: 30588436
Research progress about the effect and prevention of blue light on eyes

Maybe The Seoul Sunlike (mid power) LED might interest you.

thanks for your contributions :slight_smile:


very helpful, thanks

so, do you have any quantifyable blue light levels data for
an Incandescent, and the
sw45k N219b 9080, and the
sw35 9080, and the
E21a 3000k, and the
Optisolis 6500k (I expect this one is best used as a worklight, when staying awake is desireable)

fwiw, my computer and iPhone have NightShift enabled, and my house lights are incandescent

bob_mcbob tested the Nichia 219B in a FW3A, if you look at his TM-30 tests you will see that it has a blue spike.
You will find the spectral power distribution of the E21A 3000K and optisolis 6500K on clemence’s website or here for the E21A and here for the optisolis (see imgur link in the message). The 6500K has a lot of blue which is not surprising since it is made to be as close as possible as the reference (D65 standard) which is daylight (above BBL).

thank you

since the N219b is rated for no blue light hazard, the presence of a blue spike is not sufficient info

Im looking for reference number values,
so we can begin to have a conversation about
How Much blue light is being produced

as pinkpanda pointed out, the amount of blue light from a blue tritium for example, may or may not have enough output to impact melatonin and suppress sleep, I do not know

I need numbers… like

X blue units from a N219b is Not capable of suppressing melatonin
Y blue units from a cool white fluoro IS capable of suppressing melatonin

numbers so I can compare the relative blue outputs, and numbers that tell me a threshhold value for the “no Blue Light Hazard” designation

I see what point you’re trying to make, but ‘directly causally linked to’ doesn’t make any sense, so that’s not what the article is saying

I don’t know how one could segregate blue light from a given light source and calculate the levels of effect? Especially when “light of any kind can suppress the secretion of melatonin”. Imagine slowly turning on one of your rrt-01 lights. At which point does the light have an affect?

If the study that teacher linked was correct - “Even dim light can interfere with a person’s circadian rhythm and melatonin secretion. A mere eight lux —a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect” Then what?? Lower the light level by a quarter of a lux and you’re golden right :innocent: YehNO , as always life is messier than that.

This discussion is like saying don’t eat hamburger and chips because it’s unhealthy. If it was the only thing you ate then yes unhealthy. If it was mixed in with a regular half healthy diet then you couldn’t pin point that as being the major factor for being overweight. More likely the lack of exercise is the reason which totally gets ignored because it’s too hard.

I understand some people like to go over the science of it all but really, who is going to change their lifestyle because of the Blue Light Fear . Turn the house lights down dim in the evenings and don’t look at screens 2-3hrs before sleep.

EDIT- Looking at my last sentence makes me wonder if that has anything to do with the world population growth rate slowing down :laughing: :laughing: :laughing: or am I reading into that too much? :laughing:

I’m more concerning about the excessive light we continuously put outside our “caves”. Human evolved with day time/night time cycle. Face it, we’re currently in the progress of day time/not-so-dark night cycle evolution. It’s impossible to get back to the stone age. Let the science and technology slowly find the answer. In the meantime you can try your best to minimize the harmful effect (if there’s any) in sensible and practical ways.

I myself don’t have any problem sleeping/trying to sleep under any light source. The problem is when I wake up, CW hurts my eyes more than warm white.


Life itself is deadly, everything can kill you, eventually.

I’ll be BBQing tomorrow.


I don’t have an incandescent to test but I tested a heat lamp with 100CRI and almost no blue light and 0.000 DUV at 2800K. I think incandescent is similar.

SW45K 219B 9080 has very high blue light intensity. I can’t find a 70CRI 4500K to compare with at the moment but it is definitely not a light to shine directly in your eyes.

I haven’t tried the SW35 yet. I haven’t tried Optisolis 6500K. I never go above 5000K unless it is for a pure thrower. I measured sunlight from 3000K to 5700K depending on time of day. Cloudy day can be 6000K+ but I prefer sunlight over cloudy day.

E21A, 2070K, 95.5 CRI, blue peak intensity of 0.07
E21A, 3061K, 96.2 CRI, blue peak intensity of 0.45
E21A 2x2000K and 2x4000K, 2828K, 94.5 CRI, peak intensity of 0.40
The SST-20, 2910K, 96.9CRI has a blue peak intensity of 0.38
The XP-L2 HD V4 7A, 3168K, 72.1 CRI, blue peak intensity of 0.76 and a DUV of –0.0029 (tint is real good btw).
XP-L HD, 2958K, 70.1 CRI, blue peak intensity of 0.39
XP-E HEW Q3 7A2, 3311K, CRI 89.8, blue peak intensity of 0.57
Nichia 219B 3000K 9080, 3391K, CRI 95.2, blue peak intensity of 0.57
Yuji, 3191K, CRI 96.6, blue peak intensity of 0.060
Optisolis 2700K, measures 2973K, CRI 97.5, blue peak intensity of 0.41
Oslon Square 92 CRI 6X tint, 2746K, CRI 91.3, blue peak intensity of 0.29
Oslon Square 96 CRI 6U tint, 2831K, CRI 95.9, blue peak intensity of 0.26
Oslon Square 92 CRI 5Q tint, 3346K, CRI 94.9, blue peak intensity of 0.61

It’s real hard to quantify blue light. The blue peak intensity above is relative to the rest of the spectrum for that emitter. The actual amount depends on the lumen output also. In order to get a good comparison of blue wavelength, you would have to overlay the graphs, which is too difficult and too much work to do. However, I think the blue peak intensity is a pretty good indicator of how much blue wavelengths is emitted by the emitter for these warm white CCTs.

If you want to experiment, visit a professional photography or theater lighting store that carries colored filter sheet material.
20 x 24 inches, sheet costs about $7ish. Pricier from Amazon etc.

Ask for a little sampler pack, often given free, with strips of all colors, big enough to cover a 20mm flashlight lens.
You can see the transmission spectrum for each filter type too.

I have a sheet of this one taped so I can flip it over the computer screen in the evening:

Nobody has suggested just dimming your lights to reduce the blue? I have trouble falling asleep, and recently installed some very dim indirect lighting and began dimming my monitor’s back-light to minimum at night. It has definitely helped. Same ratio of colors, just far less of everything, including blue.

Here’s a comparison of the effect on melatonin of ordinary room light (less than 200 lux) compared to dim (less than 3 lux) light:

J Clin Endocrinol Metab. 2011 Mar; 96(3): E463–E472.
Published online 2010 Dec 30. doi: 10.1210/jc.2010-2098
PMCID: PMC3047226
PMID: 21193540
Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans

FYI that’s completely untrue. Reducing caloric intake by even a small amount is equivalent to a huge amount of exercise.

Here’s the spectrum plot for that light at the ramp ceiling.

I think youre on to something, blue light associated with reduced sex drive… LOL!

or, am I reading something into it that was not there?

You’re missing the point I was trying to make. Let’s delete the exercise part of what I wrote (because obviously it’s too hard :person_facepalming: ) If one is overweight and consuming too much are you going to entirely blame it on the occasional burger and chips???

Nope :wink:

Please clarify. Are you referring to this in relation to losing weight??

Because as far as I know “reducing caloric intake” has no effect on building cardio strength or the other benefits of exercise.