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[UV SAFETY] UV and Your Eyes :: UV Safety Reference


Andrea B.

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Pylon, I need you to simply give up your idea to UV-flash photograph any models or yourself. Most certainly you can be creative with UV photography and models in other ways that do not involve UV-flash.

 

I would remind you that you are opening yourself up to all kinds of lawsuits here in the litigious US if you UV-flash people, and they later decide that you have somehow screwed up their eyes and/or skin !!

 

As for your new questions, while they are very good, they require research into the medical literature to see if answers exist.

 

Our resident expert on biochemical issues is John Dowdy, so I suggest you contact him privately to see if he can be of any assistance. Although I think he will simply repeat what we have said before: no UV-flash in human or animal eyes.

 

***************************

 

I was assuming that the contact lenses would cover the entire pupil+iris (I didn't know smaller contact lenses existed?) and would block UV to a significant degree.

Contact lenses: Gas permeable contact lenses are tiny and do not cover the entire pupil.

 

My original thinking (and I still do think this), is that if you go out in the sun for 5 minutes, that is not going to kill you or be extremely harmful to your skin in anyway, for the average person who is semi-adapted to being in the sun for extended periods.

The UV damage is CUMULATIVE.

 

"Safe", in my current conception of the word, is not permanently damaging a functional biological system beyond natural repair, and no more than 1 year taken off the organisms estimated lifespan, and not increasing someone's risk to developing a cancer within their estimated lifespan by more than 2%. Maybe there is a better definition although this is what I came up with, I am not sure how to incorperate the idea of cumulative damage into a defintion of "safe", other than the more decisions you make to avoid radiation on a day-to-day basis during your life as a whole, the more slack you would have when making the decision to get exposed to it every now and then; it wouldn't be increaing your cumulative risk as much.

Unless you have actual medical data to support this concept of "safe", then it is just so much hogwash. What are you trying to do - play God with such silly statements as 'no more than 1 year taken off an organisms life span'? Who are you to even make such statements? And for many types of UV damage, there is NO natural repair.

 

I am not sure how to incorperate the idea of cumulative damage into a defintion of "safe".

Well, you don't.

 

measuring the amount of UV-A radiation from a flash

Look up the manufacturer's data. UV-flashes also put out UV-B.

 

If you were to take photos of a person wearing material that fluoresces brightly, such as white cotton or UV-reactive contact lenses, would that be any more damaging to the person wearing those things (or even you as the photographer who receives the bounced-back light) than if they were wearing material that does not fluoresce as bright?

Most UV-induced fluorescence is visible light - which is why you can see it. What you cannot see is any possible UV-reflection.

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Pylon, I need you to simply give up your idea to UV-flash photograph any models or yourself.

 

Giving up now would not make any sense. Surely there is a solution for protecting skin and eyes from UV-A radiation?

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Presumably you have read the various recommendations across the site to wear UV-blocking goggles. And protective clothing. (Although I do not have much info on that at hand.)

 

I think we have adequately covered the protection thing.

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I know about safety glasses, and that thicker/denser clothing would give you more protection. That is covered :)

 

Sunscreen is what I was wondering about.

 

"Studies over the years have shown that sunscreen with an SPF, or sun protection factor, of 30 blocks about 97 percent of ultraviolet rays. A rating of 15 means 93 percent of UV rays are blocked, and anything higher than 30 remains in the 97 or 98 percent range" ...... "What many people do not realize is that the amount of sunscreen applied plays an enormous role. A study in The British Journal of Dermatology this year found that applying less than two ounces over the entire body at one time can leave people with an SPF rating far lower than what is on the bottle" - http://www.nytimes.c...7real.html?_r=0

 

I was assuming zinc oxide SPF 30 sunscreen would be an adequate form of protection, if flashing a human many times, as that is what I was going to use, along with safety-glasses for eye protection (by default. The contact lens idea was just an idea).

 

Was just wondering if anyone had anything better to recommend, or if they think taking pictures of people with their eyes closed with sunscreen applied to their lids and rim would be safe.

 

Will be waiting to see any responses.

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You will get some pretty weird portraits of these goggled, sunscreened people.

Go look in our Portrait section to see what sunscreened people look like.

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I'm new here but I'd like to chime in.

 

I have been taking UV portraits and have worked with very strong UV lasers, both puilsed and continuous wave so the question of safe UV exposure is of interest to me. For my portrait work I use a pair of 26W CFL blacklight blue bulbs for illumination. The bulbs are about 1.5m away from my subject (usually me) and are about 25% efficient. This yields about 13W of actual UV power from the bulbs ranging between 325nm to 405nm peaking at around 365nm. Assuming the reflectors are 100% efficient (a big assumption) and based on my experience with the reflectors with visible incandescent bulbs the reflected intensity is not strongly focused I estimate the intensity of the lights in the focal plane to be <1W per square meter. A 1s exposure is sufficient for a good image with an unmodified Nikon D40. I would assume a camera modified for full spectrum would need even less.

 

Regarding fluorescent blacklights a quick look at the spectrum of these bulbs (attached) shows they are a nearly ideal source for UV photography, e.g. lots of UV with negligible visible light and no IR.

 

I would suggest anyone concerned about exposure to continuous wave light sources during setup use a shutter or curtain to block the UV source except for the few seconds its needed.

 

Regarding adequate eye protection I have tested my prescription eyeglasses in a spectrophotometer. I found they transmitted negligible amounts of UV. Polycarbonate itself is great at absorbing UV light (see attched spectrum) and I imagine any AR and antiscratch coatings on eyeglasses can only help block UV. Polycarbonate safety glasses can be an option for those who don't wear prescription glasses.

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enricosavazzi

As UVP's resident photobiologist and UV photosafety expert I have been meaning to open a posting on this topic and I apologize for not finding the time to take the lead on this. There are many variables to consider some of which are mentioned above and some of which I have commented upon from time to time.

[...]

John,

 

I found a few brief mentions of the fact that the exposure time to UV (in addition to the total amount of UV radiation, i.e. time x intensity) affects the biological risk. Some of these information sources (mostly Internet, and I was unable to find any "hard" references) state that some organic macromolecules can be damaged by a one-photon UV strike, but recover (i.e. repair themselves, perhaps by reforming the temporarily broken atom-to-atom links, or are repaired by cellular mechanisms) within a short time. If a second UV photon strikes the molecule at a critical position before the first damage is repaired, the cumulative damage may be beyond repair.

 

If confirmed, this may mean that exposure to UV xenon flash is far more dangerous than exposure to the same amount of UV emitted by a lower-intensity continuous source over a longer time. This also depends on the time required by these molecules to repair. If it takes minutes or longer, then it probably does not matter whether the UV source is flash or continuous, in the conditions we normally use to record UV images (our exposures are typically less than a minute). If it takes milliseconds or less, then it does matter whether we use flash or a continuous source.

 

Are you aware of any reliable references to this behavior of organic macromolecules?

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Lost Cat (name??) --

 

Go to the beginning of this topic and read the information about Recommended Maximum UV Exposure and Eye Damage from UV Exposure.

 

No human subject should be sitting for a UV portrait under artificial UV illumination of any kind for any amount of time.

UV eye damage is cumulative and not repairable.

 

Especially do not damage a child's eyes from any exposure to artificial UV illumination because children's eyes have not yet been able to build any yellowing of the cornea to block harmful UV and violet rays. Artificial UV illumination is even harder on young eyes than on old ones.

 

Anyone who feels the necessity to make UV portraits should simply take their subject out into the sunlight. Yes sunlight has its risks, but so much less so than from artificial UV illumination.

 

Also note that if your prescription glasses do not wrap around your eyes, then they are not sufficient protection. You will receive a lot of UV from reflections which enter at the side of your glasses. And you can't see it comin' so you don't even know it is happening !!

 

You have estimated the UV light intensity on the focal plane to be 1 Watt/m2. What is needed is the UV light intensity on the human subject at a distance of 1.5 meters ?? Then you can use the recommendations above to calculate the maximum exposure time for an 8 hour day.

 

However, just because there is a recommended exposure time does not mean that there is no damage done by artificial UV illumination. I think this is the part which is missed by everyone. We calculated above that maximum exposure to a Blak-Ray B-100 lamp at a 5 cm distance is 46 seconds within an 8 hour day. That does NOT mean that those are 46 safe seconds. They are not. UV damage is cumulative.

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UV light is dangerous. The posted contact lens pic does nothing to make it look safe to me, in fact that pic looks to me like the contact transmits UV, and only covers part of the eye.

Glasses and contacts may be designed to block UV from sunlight to whatever extent, but they are not designed for intensities from torches, flashes, etc..

 

I have also seen posts about UVC sterilization bulbs, which are designed to kill, that is what they are for. They have strict warning labels on them, they are used inside of self contained compartments to kill things.

So if you use those, wire it all up so you are in another room, and make sure there are not pets or living things in the room you shoot UVC!

Any exposure to UVC should be out of the question.

 

So as public posts, these ideas should not be played around with for people who may read part of these ideas and then go lighting their homes and their eyes (skin even) with UV .

You are worth more than any photography hardware.

Just my 2 cents that I was trying to save for a UV-Nikkor.

 

Outdoor light works just fine for me when it comes to faces.

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Lost Cat (name??) --

 

Jim

 

Go to the beginning of this topic and read the information about Recommended Maximum UV Exposure and Eye Damage from UV Exposure.

 

I did. I also have many years of experience working with very high intensity UV lasers. I don’t take UV exposure lightly.

 

No human subject should be sitting for a UV portrait under artificial UV illumination of any kind for any amount of time.

UV eye damage is cumulative and not repairable. Especially do not damage a child's eyes from any exposure to artificial UV illumination because children's eyes have not yet been able to build any yellowing of the cornea to block harmful UV and violet rays. Artificial UV illumination is even harder on young eyes than on old ones.

 

Which is why I have my subjects close their eyes or wear eye protection when exposed to UV

 

Anyone who feels the necessity to make UV portraits should simply take their subject out into the sunlight. Yes sunlight has its risks, but so much less so than from artificial UV illumination.

 

Sunlight is far more UV intense than at least my artificial portrait lights. Please see below

 

Also note that if your prescription glasses do not wrap around your eyes, then they are not sufficient protection. You will receive a lot of UV from reflections which enter at the side of your glasses. And you can't see it comin' so you don't even know it is happening !!

 

Depends. If the UV light comes mainly from one direction – direct line of sight from the lamps – eyeglasses should indeed provide adequate protection as the eyes will be in the “shadow” of the lenses. Far more protection than when outdoors where reflective surfaces are much less controllable.

 

You have estimated the UV light intensity on the focal plane to be 1 Watt/m2. What is needed is the UV light intensity on the human subject at a distance of 1.5 meters ?? Then you can use the recommendations above to calculate the maximum exposure time for an 8 hour day.

 

Perhaps I misused the term. I meant the plane my cameras are focused on which is also the position of my subject (again usually me). This plane is 1.5 meters away from the lamps so it receives in my estimation less than 1W/m2. The sun delivers 1120W/m2 of light to the surface of the earth of which 3-5% is below 400nm or about 34-56W/m2 a portion of which is UVB and UVC neither of which are produced by my BLB lamps:

 

https://en.wikipedia.org/wiki/Sunlight

 

As far as UV intensity goes I'll take my 0.9W/m2 lamps over the 34-56W/m2 of the great outdoors any day. At least for the few seconds it takes to snap the shot.

 

However, just because there is a recommended exposure time does not mean that there is no damage done by artificial UV illumination. I think this is the part which is missed by everyone. We calculated above that maximum exposure to a Blak-Ray B-100 lamp at a 5 cm distance is 46 seconds within an 8 hour day. That does NOT mean that those are 46 safe seconds. They are not. UV damage is cumulative.

 

No argument there – the Blak-Ray B-100 you mention uses a 100W fluorescent lamp, which is 2x stronger than my 2x26W lamps at a working distance 30x closer (5 cm vs. 150 cm), yielding an overall intensity 1,800x greater.

I should mention I am hoping to use my portraits as a tool to convince people of the need to use sun protection and perhaps track skin damage with age. If sitting under my relatively meek UV lights for a few seconds convinces someone to wear sun protection for the rest of the day I think overall that's a win.

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Which is why I have my subjects close their eyes or wear eye protection when exposed to UV

 

Jim - thank you, thank you, thank you for supporting responsible Artificial UV Illumination !!!! :lol:

You have eased my mind.

 

Recently I felt as though I was becoming the Artificial UV Illumination Police with all my attempts to warn naive users of UV lamps/flashes/torches/bulbs about the dangers they might encounter or the harm they might do. It is difficult to maintain a website for UV photography sometimes because there is some inherent danger in the lighting aspects of the art, so we must provide warnings. I'm happy to know that you - along with our bio guy John Dowdy - can help me with this effort.

 

I would still suggest a pair of wrap around UV-block goggles. The UV light entering behind glasses might not hit your pupil, but can still damage the conjunctiva. Edmund Optics makes a pair of UV-blockers with vents for cheaps. They are real cute and provide the wearer with a space alien look.

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Which is why I have my subjects close their eyes or wear eye protection when exposed to UV

 

Jim - thank you, thank you, thank you for supporting responsible Artificial UV Illumination !!!! :lol:

You have eased my mind.

 

Recently I felt as though I was becoming the Artificial UV Illumination Police with all my attempts to warn naive users of UV lamps/flashes/torches/bulbs about the dangers they might encounter or the harm they might do. It is difficult to maintain a website for UV photography sometimes because there is some inherent danger in the lighting aspects of the art, so we must provide warnings. I'm happy to know that you - along with our bio guy John Dowdy - can help me with this effort.

 

I would still suggest a pair of wrap around UV-block goggles. The UV light entering behind glasses might not hit your pupil, but can still damage the conjunctiva. Edmund Optics makes a pair of UV-blockers with vents for cheaps. They are real cute and provide the wearer with a space alien look.

 

Glad to hear it. I do hope though that we can keep the caution to a reasonable level without crashing into an abyss of hysteria. Humans, at least the ones I know are not like vampires, disappearing into a pile of ash when touched by a beam of sunlight. Most humans CAN tolerate a dose of UV now and then; indeed, according to the World Health Organization its actually good for you:

 

http://www.who.int/entity/uv/health/en/uvexposure.jpg

 

http://www.who.int/uv/health/en/

 

I suppose if it makes one feel better one can limit artificially lit UV portraiture to winter months when environmental UV exposure is minimized.

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Skin fine. Eyes no.

 

Anyway, I'm only slightly hysterical on alternate Thursday afternoons between 3 and 5 PM about UV in the eyes. It's just that I had 4 eye surgeries on my left eye from a double cataract and consequent complications. No fun.

 

My lens implant blocks UV (of course) and some of the "bad" violet and blue. Interestingly, with the left eye I can detect some spectral violet leak from one of my 365nm UV-LEDs. I only just realized this recently. But not so with the right eye which still has the aging, yellowed cornea which we all develop. Also blue looks bluer with my left eye and more cyanish with my right. We do not detect this loss of truly blue blues as it is happening over the years. I cannot detect UV at all and do not want that particular superpower.

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John,

 

I found a few brief mentions of the fact that the exposure time to UV (in addition to the total amount of UV radiation, i.e. time x intensity) affects the biological risk. Some of these information sources (mostly Internet, and I was unable to find any "hard" references) state that some organic macromolecules can be damaged by a one-photon UV strike, but recover (i.e. repair themselves, perhaps by reforming the temporarily broken atom-to-atom links, or are repaired by cellular mechanisms) within a short time. If a second UV photon strikes the molecule at a critical position before the first damage is repaired, the cumulative damage may be beyond repair.

 

If confirmed, this may mean that exposure to UV xenon flash is far more dangerous than exposure to the same amount of UV emitted by a lower-intensity continuous source over a longer time. This also depends on the time required by these molecules to repair. If it takes minutes or longer, then it probably does not matter whether the UV source is flash or continuous, in the conditions we normally use to record UV images (our exposures are typically less than a minute). If it takes milliseconds or less, then it does matter whether we use flash or a continuous source.

 

Are you aware of any reliable references to this behavior of organic macromolecules?

 

Enrico,

 

Well, where to start.

 

The concept you are referring to is photobiological reciprocity which basically says that a photo effect is dependent on the exposure dose (intensity x time) but not the intensity or time alone.

 

10 Joules/unit area = 1 Watt/unit area x 10 seconds = 10 Watts/unit area x 1 second

 

However, in complex biological systems where there are often multiple chromophores, overlapping reactions and repair mechanisms true reciprocity can only exist over a finite dose range, if at all.

 

An accessible resource is the free online textbook Photobiological Sciences Online (http://www.photobiology.info/) posted by the the American Society for Photobiology (ASP). I would suggest the module on Biological Action Spectra in the Spectroscopy chapter, specifically the section heading Reciprocity Should Hold. Also, the module Basic Ultraviolet Radiation Photobiology in the UV Radiation Photobiology chapter gives an overview of the complexity.

 

In one sense when UV damage or injury occurs it is a form of reciprocity failure, at least from the perspective of maintaining homeostasis. On the other hand, threshold injury responses, such as sunburn, do generally follow a dose reciprocity rule within a limited time frame.

 

The intensity required to enter into more exotic multiphoton photoexcitation is a good bit higher than is achievable with photographic strobes as far as I am aware. Normal UV repair processes are not as fast as a strobe or even a short exposure to a continuous source but strobes can accumulate high doses faster if repeatedly pulsed.

 

I am actually more concerned with the unnecessary short wavelengths present in unshielded quartz Xe strobes. Same as with a continuous source, shorter more energetic wavelengths are generally more hazardous. I am considering filtering a UV modified flash with a Schott WG-320 or WG-305 in order to better reproduce the UV spectral balance of sunlight and reduce the risks from shorter wavelengths.

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Bill De Jager
I am actually more concerned with the unnecessary short wavelengths present in unshielded quartz Xe strobes. Same as with a continuous source, shorter more energetic wavelengths are generally more hazardous. I am considering filtering a UV modified flash with a Schott WG-320 or WG-305 in order to better reproduce the UV spectral balance of sunlight and reduce the risks from shorter wavelengths.

 

Thanks for the product names! I have a couple of units with these quartz tubes. Though I haven't used them yet, I've been concerned about incidental exposure - both to me and to the surroundings. UV goggles are one thing but full-body protection (and protection of any sensitive materials in the same room) would be a lot more hassle. I don't want to mess around with UV-B or UV-C!

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So, you have a little under 2 minutes of time to have unprotected UV-light with your Blak-Ray B-100 lamp

at a distance of 25 cm (10") within an 8-hour day.

 

So this is for both skin and eyes? I suppose these organizations didn't really specify/separate exposure recommendations for eyes and skin, respectively.

 

I found this product for head/face protection: https://www.amazon.c...0?ie=UTF8&psc=1

One could wear this to protect against the ambient reflections one gets exposed to when working with UV light sources. Will definitely come in handy, especially when more powerful UV torches come out (ones that are 10x more powerful than the MTE 301). I would think the "UPF" protection rating means that it is reducing 98% of sunlight UV radiation, I wonder if that 98% blocking rating is true for more powerful UV radiation sources though.

 

I asked if it protects against UV-A, B, and C, and LEAGY responded saying that it did, however I am not going to take their word about it being able to protect against UV-C to an adequate level.

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enricosavazzi

I am somewhat skeptic about woven cloth being used as a UV screen, at least if it is meant to cut out as much UV as possible. Cloth can be stretched, and when stretched one can usually see rather well through the holes between threads, certainly more than the 2% said not to be blocked (indirectly, by specifying 98% absorption). Wet or moist cloth can also have very different UV transmission than dry.

 

I have a few "UV-proof" long-sleeve shirts from Adidas that worked for me to prevent sunburn during a trip to Australia last year, but if I put a single layer of the cloth in front of my eyes I can see through the threads without problems, even without stretching the cloth. So a significant amount of light goes straight through. Blocking 90-95% of radiation is good enough to prevent sunburn in normal conditions.

 

These clothing items may be adequate enough for this purpose, but not against much stronger artificial UV sources or against UV-C sources. I would try to use a truly UV opaque flexible film (not a cloth, although a continuous film laid onto a woven substrate would work) for protection, with well-designed light traps for the parts meant to provide ventilation.

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