Cancer warning: UV curing

[Haenk]

https://phys.org/news/2023-01-uv-emitting-dryers-dna-mutations-cells.html

[Gyro]

No big surprise there. UV sources have long been known to cause skin cancer, be it the Sun, UV gas discharge tubes etc. It's just that these UV wavelengths are now becoming available at reasonably high intensities from LED sources.

[DavidKo]

You can apply the same article on all areas where intensive UV is produced. Probably get a good grant for the study, which has nothing new inside. Children should not go on direct sunlight during summer, people should use protection during welding, etc.

[Psi]

There is no 'safe' limit for anything, it's just when the risks are generally considered acceptable to take.

[Haenk]

Ignore as you will, that was just a little hint as the UV cured stuff (glue, paint, lacquer) became pretty popular in recent years and might be used by a lot of people with no technical background now.
While there are many countries with high UV dosis - and people are used to deal with the dangers - there are countries with permanent vitamin D deficieny 

[Berni]

The dangers of UV light have been known for many decades.

The only UV light that is deemed safe is the UV-A wavelengths (315 to 400nm). This is the what you get when standing out in the sun, it is what gives you a tan and so it is what suntanning beds use.

The shorter wavelenths of UV light start having enough energy to rip apart regular molecules (the ones that are not specifically light sensitive) including DNA. This is when you get to UV-B light, this is what the ozone layer blocks, hence why we want to protect the ozone layer. But it is still right on the edge of being harmful so prolonged exposure is needed for a significant effect. When you go even shorter in wavelength you get to UV-C light, here it really gets harmful as the photon energy gets high enough to pretty reliably rip common molecules apart, it quickly makes color dies fade, plastics become brittle, irritates organic tissue..etc. Luckily this kind of UV light is stopped by even just normal air, so even without the ozone layer you don't get exposed to it. However there are manmade sources of UV-C like welding arcs or UV lamps used for disinfection/photolithography/chemical activation etc..

These nail curing lamps go into the UV-B so they are are the same kind of dangerous as being in the sun for extended periods in places with a weak ozone layer.

[bidrohini]

We have to be careful about all UV sources.

[Gyro]

Ignore as you will, that was just a little hint as the UV cured stuff (glue, paint, lacquer) became pretty popular in recent years and might be used by a lot of people with no technical background now.
While there are many countries with high UV dosis - and people are used to deal with the dangers - there are countries with permanent vitamin D deficieny 

I didn't mean to sound dismissive. The wider availability low cost UV sources (LED) is bringing exposure into places where you wouldn't have previously come across them - much like [Edit: poorly regulated unregulated] Class IV laser applications.

...
The only UV light that is deemed safe is the UV-A wavelengths (315 to 400nm). This is the what you get when standing out in the sun, it is what gives you a tan and so it is what suntanning beds use.
...

UV-A sunbeds are far from having a clean bill of heath when it comes to cancer risk. They are illegal to use under the age of 18 in the UK for instance, for that very reason.

https://www.nhs.uk/common-health-questions/lifestyle/are-sunbeds-safe/

[jpanhalt]

There is no 'safe' limit for anything, it's just when the risks are generally considered acceptable to take.

Nitrogen is known to be quite toxic, but it is roughly 78% of what we breath.  "Nitrogen narcosis."  Try breathing it under more than a few fathoms of water.  That's the example I usually use.

[Benta]

Well, then it's back to using thinner-based (acetone) nail varnish instead.
That's also much healthier.   
@Haenk, how is this a project? Enlighten me, please.

[Zero999]

UV curing of nail gel and glues is nothing new. It just used to be done using fluorescent lamps, but now LEDs have started to take over.

The dangers of UV light have been known for many decades.

The only UV light that is deemed safe is the UV-A wavelengths (315 to 400nm). This is the what you get when standing out in the sun, it is what gives you a tan and so it is what suntanning beds use.

Did you read the article? It says 315nm to 400nm is not safe.

The ultraviolet nail polish drying devices used to cure gel manicures may pose more of a public health concern than previously thought. Researchers at the University of California San Diego have studied these ultraviolet (UV) light emitting devices, and found that their use leads to cell death and cancer-causing mutations in human cells.

The devices are a common fixture in nail salons, and generally use a particular spectrum of UV light (340-395nm) to cure the chemicals used in gel manicures.

I can't say I'm that surprised. Even the shorter end of the visible spectrum is not entirely safe.

[Stray Electron]

- there are countries with permanent vitamin D deficieny 

  They're known that since at least the 1930s. That's why vitamin D is added to milk ( "Vitamin D added" is printed right on the label ) and many other food products in the US. The dangers of high intensity UV exposure have been known at least since at least  the same time.  That's why there are strict safety regulations concerning the exposure to arc welding and other processes. The dangers of UV exposure from mercury vapor rectifier tubes and to the UV from the mercury pools that used to be user to rectify very high electric currents were also well know MANY years ago.  IRC one of the classical books about CRTs that was published in the early 1930s went into considerable detail on the subject.

  The only thing that has changed is that now dangerous amounts of UV can be generated by people at home that have no idea of what their doing and not just industrial processes that were operated by professionals.

[Stray Electron]

UV curing of nail gel and glues is nothing new. It just used to be done using fluorescent lamps,

   Probably the same florescent tubes that were used for germicidal lamps and for erasing EPROMS. Those tubes had quartz envelopes instead of glass so the output contained huge amounts of UV-C, unlike regular glass tubes which blocked most of the UV-C.   I still have some of the 1970s vintage EPROM erasers and the bulbs say "Germicidal Lamp" right on them. All of those EPROM erasers, even the cheap ones, had interlocks on them so that the lamp could only be turned on when the eraser was closed. 

[Zero999]

UV curing of nail gel and glues is nothing new. It just used to be done using fluorescent lamps,

   Probably the same florescent tubes that were used for germicidal lamps and for erasing EPROMS. Those tubes had quartz envelopes instead of glass so the output contained huge amounts of UV-C, unlike regular glass tubes which blocked most of the UV-C.   I still have some of the 1970s vintage EPROM erasers and the bulbs say "Germicidal Lamp" right on them. All of those EPROM erasers, even the cheap ones, had interlocks on them so that the lamp could only be turned on when the eraser was closed.

Those are not florescent lamps, but germicidal low pressure mercury lamps, since they lack the phosphor and no, those were never used for curing nail gel, which requires a much longer wavelength. Germicidal lamps emit UVC, rather than UVA and are much more dangerous.

[Mechatrommer]

warning, sugar can cause diabetes, salt and beer can cause kidney failure, esp beer can cause mental disorder... bla bla bla... who give a rat arse?

[james_s]

  The only thing that has changed is that now dangerous amounts of UV can be generated by people at home that have no idea of what their doing and not just industrial processes that were operated by professionals.

New since when? 70 years ago you could buy home tanning lamps that consisted of a bare quartz mercury arc tube in a reflector with a resistive ballast. As recently as the 90s you could buy mercury blended sunlamps that emit a dangerous amount of UV at any department store. UV is ionizing radiation, the dangers have been known for many, many years. At some point a person is solely responsible for their own safety, any number of readily available products can injure or even kill you if used improperly or without adequate protective gear.

[Zero999]

  The only thing that has changed is that now dangerous amounts of UV can be generated by people at home that have no idea of what their doing and not just industrial processes that were operated by professionals.

New since when? 70 years ago you could buy home tanning lamps that consisted of a bare quartz mercury arc tube in a reflector with a resistive ballast. As recently as the 90s you could buy mercury blended sunlamps that emit a dangerous amount of UV at any department store. UV is ionizing radiation, the dangers have been known for many, many years. At some point a person is solely responsible for their own safety, any number of readily available products can injure or even kill you if used improperly or without adequate protective gear.

Only the higher end of the UV spectrum is considered ionising, but the lower part can still instigate chemical reactions, which damage DNA.

My mum had one of those UV lamps. It consisted of an incandescent and mercury lamp enclosed in the same glass envelope. The incandescent lamp acted as a ballast for the arc and provided some heat and visible light. It wasn't much good as a tanning lamp, because it produced more UVB, than UVA. I did get a nasty burn playing around with it, when I was a teenager.

[ejeffrey]

The dangers of UV light have been known for many decades.

The only UV light that is deemed safe is the UV-A wavelengths (315 to 400nm). This is the what you get when standing out in the sun, it is what gives you a tan and so it is what suntanning beds use.

<snip>
These nail curing lamps go into the UV-B so they are are the same kind of dangerous as being in the sun for extended periods in places with a weak ozone layer.

The article specially says that the lamps in question operate from 350nm to 400nm in the UV-A range.

[james_s]

My mum had one of those UV lamps. It consisted of an incandescent and mercury lamp enclosed in the same glass envelope. The incandescent lamp acted as a ballast for the arc and provided some heat and visible light. It wasn't much good as a tanning lamp, because it produced more UVB, than UVA. I did get a nasty burn playing around with it, when I was a teenager.

They made lots of those for general illumination too, they were called self ballasted mercury lamps here and "mercury blended" in some other parts of the world. They were not any more efficient than incandescent but they did offer substantially longer lifespan. They had a tungsten filament and a mercury arc tube mounted within the same outer bulb. I believe the sunlamp versions used a different type of glass to let out more of the UV.

I had another type of old tanning lamp that we found in a 1960s house my friend bought. It was just a bare quartz arc tube in a reflector with a wire grill over the front and nichrome heating wire strung across to either side of the arc tube. The only time I played with it I set it behind a piece of glass to block the UV.

[Gyro]

Those are not florescent lamps, but germicidal low pressure mercury lamps, since they lack the phosphor and no, those were never used for curing nail gel, which requires a much longer wavelength. Germicidal lamps emit UVC, rather than UVA and are much more dangerous.

This reminds me of a 6" 4W tube that I picked up in a junk shop years ago. It was an educational tube (Griffin I think), that was half florescent, half clear along its length. Closer inspection revealed that it had the characteristic ripple marks of a fused quartz tube and that the half length phosphor was applied to the outside of the tube. This thing was clearly intended to show school kids how florescent tubes worked, presumably at close range if they were going to be able to see the filament glowing at the clear end, and the pretty blue glow!

I cleaned off the external phosphor and it still lives in my home made EPROM eraser to this day.

[james_s]

This reminds me of a 6" 4W tube that I picked up in a junk shop years ago. It was an educational tube (Griffin I think), that was half florescent, half clear along its length. Closer inspection revealed that it had the characteristic ripple marks of a fused quartz tube and that the half length phosphor was applied to the outside of the tube. This thing was clearly intended to show school kids how florescent tubes worked, presumably at close range if they were going to be able to see the filament glowing at the clear end, and the pretty blue glow!

I cleaned off the external phosphor and it still lives in my home made EPROM eraser to this day.

Yikes. I've seen pictures of demonstration prototype lamps that were half phosphored, but the phosphor was on the inside and they were made of ordinary glass that absorbs the UV.

[NiHaoMike]

This reminds me of a 6" 4W tube that I picked up in a junk shop years ago. It was an educational tube (Griffin I think), that was half florescent, half clear along its length. Closer inspection revealed that it had the characteristic ripple marks of a fused quartz tube and that the half length phosphor was applied to the outside of the tube. This thing was clearly intended to show school kids how florescent tubes worked, presumably at close range if they were going to be able to see the filament glowing at the clear end, and the pretty blue glow!

I suspect it was intended to be used in a transparent enclosure that blocks UV.

Reminds me of:

[james_s]

A friend of mine sunburned his eyes playing with a 1kW mercury reflector flood lamp. The back of the reflector glowed green but was not very bright, but it turns out it lets out quite a lot of UV. He said it felt like he had sand in his eyes for several days.

[jbeng]

... He said it felt like he had sand in his eyes for several days.

Sounds like the same kind of burn you can get when when working without eye protection near someone who is electric arc welding.  My brother was at a job and got the same burns years back. He wasn't watching the welding work, he was just working nearby.  Lesson learned there.

[Zero999]

... He said it felt like he had sand in his eyes for several days.

Sounds like the same kind of burn you can get when when working without eye protection near someone who is electric arc welding.  My brother was at a job and got the same burns years back. He wasn't watching the welding work, he was just working nearby.  Lesson learned there.

Yes, it's the typical type of injury from UV exposure. My mum told me she stupidly forgot to wear eye protection when using her tanning lamp on one occasion. Needless to say, she didn't do it again.

[james_s]

... He said it felt like he had sand in his eyes for several days.

Sounds like the same kind of burn you can get when when working without eye protection near someone who is electric arc welding.  My brother was at a job and got the same burns years back. He wasn't watching the welding work, he was just working nearby.  Lesson learned there.

Yeah arc welding makes a ton of UV light too. I've forgotten to cover various bits of skin a few times while arc welding and got a painful UV burn on a my skin.

[Njk]

Probably the same florescent tubes that were used for germicidal lamps and for erasing EPROMS. Those tubes had quartz envelopes instead of glass so the output contained huge amounts of UV-C, unlike regular glass tubes which blocked most of the UV-C.

Exactly. Medical "germicidal lamp" is a must have device. First, it can erase EPROM (the spectrum peak is just right, 253.7 nm). Second, it can heal a skin wound. Typically, a minor injure is self-healing. But sometimes not, and in that case clean the wound and expose it to UV-C light. For short time, less than a minute. Just use a mask to prevent a healthy skin around the wound from exposure. For me, it always worked excellent.

[thm_w]

"Using three different cell lines—adult human skin keratinocytes, human foreskin fibroblasts, and mouse embryonic fibroblasts—the researchers found that the use of these UV emitting devices for just one 20-minute session led to between 20 and 30 percent cell death, while three consecutive 20-minute exposures caused between 65 and 70 percent of the exposed cells to die."

This is odd because you'd think people would notice the skin death on your fingers if you regularly cure your nails?
But, I do have one of these nail curing lamps for conformal coating, and the max cure time is set as only 2 minutes, so maybe its not noticeable in that time frame.

I've also damaged some skin with a germicidal UV lamp, and its never healed properly, absolutely permanent damage, scary stuff.

warning, sugar can cause diabetes, salt and beer can cause kidney failure, esp beer can cause mental disorder... bla bla bla... who give a rat arse?

Tons of people who care about their health. 

[Njk]

But, I do have one of these nail curing lamps for conformal coating, and the max cure time is set as only 2 minutes, so maybe its not noticeable in that time frame.

Which type of conformal coating you're using? A UV-curable is not the best one, afaik

[thm_w]

But, I do have one of these nail curing lamps for conformal coating, and the max cure time is set as only 2 minutes, so maybe its not noticeable in that time frame.

Which type of conformal coating you're using? A UV-curable is not the best one, afaik

- Humiseal UV50LV UV cure
- MG chem 422C silicone conformal coating, acetone base
- Generic UV cure soldermask

No UV is not the best but there is no strong smell, so much less VOCs, and faster cure.

[Zero999]

Probably the same florescent tubes that were used for germicidal lamps and for erasing EPROMS. Those tubes had quartz envelopes instead of glass so the output contained huge amounts of UV-C, unlike regular glass tubes which blocked most of the UV-C.

Exactly. Medical "germicidal lamp" is a must have device. First, it can erase EPROM (the spectrum peak is just right, 253.7 nm). Second, it can heal a skin wound. Typically, a minor injure is self-healing. But sometimes not, and in that case clean the wound and expose it to UV-C light. For short time, less than a minute. Just use a mask to prevent a healthy skin around the wound from exposure. For me, it always worked excellent.

As mentioned above, UV curing lamps are completely different to germicidal lamps. They emit much longer, lower energy/frequency radiation, typically peaking around 360nm, which is a lot safer.

I've never heard of germicidal lamps being used on wounds. UV will kill bacteria, but also healthy tissue and can cause cancer.

Have there been any medical studies?

I would stick to ordinary antiseptic. It also damages healthy tissue, but at least it's not carcinogenic.

"Using three different cell lines—adult human skin keratinocytes, human foreskin fibroblasts, and mouse embryonic fibroblasts—the researchers found that the use of these UV emitting devices for just one 20-minute session led to between 20 and 30 percent cell death, while three consecutive 20-minute exposures caused between 65 and 70 percent of the exposed cells to die."

This is odd because you'd think people would notice the skin death on your fingers if you regularly cure your nails?

Perhaps it's because the skin cells on the surface are already dead?

I admit, I haven't read the entire study. If they've just tested it on living tissue, it doesn't prove the long wavelengths used to cure nail gel, cause cancer. Did they find out how much of the UV radiation is absorbed by the top layer of dead skin and take that into account? I would suspect a significant amount is absorbed, before it gets to living tissue.

warning, sugar can cause diabetes, salt and beer can cause kidney failure, esp beer can cause mental disorder... bla bla bla... who give a rat arse?

Tons of people who care about their health. 

There is a lot of unfounded panic over health. If you're worried, just wear glasses with a UV filter and sunscreen, when dealing with UV light. Note sunscreen is only been tested to block UVA and UVB, not UVC, and is probably no good to protect against UV from germicidal lamps and arc welding.

[Njk]

I've never heard of germicidal lamps being used on wounds. UV will kill bacteria, but also healthy tissue and can cause cancer.

Have there been any medical studies?

It must be well studied already because it's by no mean something new. I first learned about it a long time ago, in the military aviation. Poor nutrition, vet climate exhaustive duty roster, etc, etc. In that conditions, any accidental wound rarely could heal itself. A magic powders and greases usually were not effective, and the wound was getting bigger and bigger. The medical staff was well aware of that and our doctor did practice the UV therapy as the best method in such cases.

Sure if one can get enough funding, he can study that stuff all over again, as long as he wants, and to publish as many papers as he wants but I'm not interested. Because I know from personal experience that it just work. For me anyway. Of course any method can be abused. An attempt to erase all the germs by single long exposure would be a huge mistake. Use short daily exposure in the course of treatment for several days and all will be fine.

[Njk]

No UV is not the best but there is no strong smell, so much less VOCs, and faster cure.

I'm more used to 2K urethane coatings. Unfortunately, they're no more in fashion.

[thm_w]

As mentioned above, UV curing lamps are completely different to germicidal lamps. They emit much longer, lower energy/frequency radiation, typically peaking around 360nm, which is a lot safer.

I've never heard of germicidal lamps being used on wounds. UV will kill bacteria, but also healthy tissue and can cause cancer.

Have there been any medical studies?

I would stick to ordinary antiseptic. It also damages healthy tissue, but at least it's not carcinogenic.

Yeah would kill some bacteria. Apparently other effects as well, but its not extensively studied in human trials yet that I see:

It has been reported that with appropriate doses, UVC can selectively inactivate microorganisms, while preserving viability of mammalian host cells and, moreover, is reported to promote wound healing. Further, for treatment of wound infections, it is presumed that only limited numbers of repeated UVC irradiation doses would be required, while the UV-induced carcinogenic mutation is a long-term effect of prolonged use of UVC

Exposure of the skin to UV produces erythema, epidermal hyperplasia, increased blood flow in the microcirculation, and also has a bactericidal effect. 26,59 The induced erythema initiates the first phase of healing (inflammatory phase) by creating an inflammatory response via the mechanism of vasodilatation. This may be partially explained by the effects of UV light on the arachidonic acid pathway.60 In addition, UV light exposure induces cellular proliferation in the stratum corneum.61 This proliferation/thickening of the skin is a protective mechanism against further sunlight damage. UV avoidance and use of sunscreens are commonly advised during the re-epithelialization process as well as after wound closure. However, it is possible that the currently accepted practice of UV protection prevents the normal cutaneous response to injury, with melanocyte redistribution and pigmentation creating hypopigmented scars. Previous studies reported that UVC light per se could stimulate wound healing. It was found that UVC light-induced fibronectin release led to increased healing via wound contraction. 62 Fibronectin promotes cell migration and helps regulate cell growth and gene expression. Growth factors are released from epidermal cells exposed to UV irradiation, which further augments the healing cascade.

https://europepmc.org/article/med/7612137
https://www.liebertpub.com/doi/abs/10.1089/wound.2012.0366

Perhaps it's because the skin cells on the surface are already dead?

I admit, I haven't read the entire study. If they've just tested it on living tissue, it doesn't prove the long wavelengths used to cure nail gel, cause cancer. Did they find out how much of the UV radiation is absorbed by the top layer of dead skin and take that into account? I would suspect a significant amount is absorbed, before it gets to living tissue.

You are probably right, the photo is showing petri dishes. So this might be misrepresentation of the actual study.
Its not uncommon if you ask the scientists who performed the study, they will disagree with the news headline.