[UVC SAFETY WARNING] Halogen lamps are a UVC hazard?!

[Fandyus]

[UV SAFETY] UV-C Light Is Dangerous

NEVER look at a UV-C light.

NEVER let UV-C light hit your skin or eyes directly or by reflection.

UV-C light can cause:

• severe burns of the eyes and the skin, and
• DNA damage from broken chromosomes.

When working with UV-C illumination, you MUST:

• cover up completely, 
• wear head & eye protection, and
• have strong ventilation.

 

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Hello there. It's been a long time since I posted. Life got in the way. But this video just came in and it is honestly a little bit concerning.

Brainiac75 tests the output of halogen lamps and finds out they emit a small amount of UVC. I have an unfiltered 125w spotlight that I have used a few times as a lightsource and I am wondering what the implications of this are.

[dabateman]

Maybe something, and you can worry about anything. 

But my experience is that its a trival amount of UV. Even the UVA isn't enough for photography. 

Its a great light to stress test a Baader U filter though. You will see the IR leakage and little UV using a hallogen bulb as a light source. 

Some might remember my scare hallogen I have in cut glass.

[Andy Perrin]

Yeah, you can hardly even do UVA photos without a ton of S8612 on there with a halogen. I don't think there is a minimum safe amount of UVC, so I wouldn't go sitting under it for a long time with no glass, but I doubt ordinary use will hurt you. 

[Andrea B.]

 

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The short answer to Fandyus question:  Yes, halogen lamps are very dangerous unless shielded with a silica glass cover.

At a 1 cm distance from [an unshielded] halogen bulb, the UVA and UVB output mirrors that of the sun, while the UVC output far exceeds that of the sun.

 

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Members:  when answering questions about this dangerous stuff, be sure to do some research first. Give a responsible, accurate answer with references.

 

 

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The risk of ultraviolet radiation exposure from indoor lamps in lupus erythematosus

by R. Klein, R. Sayre, John C. Dowdy, V. Werth

Feb 2009

That is a link to a paper in the National Library of Medicine (US) which discusses the dangers of using Halogen Lamps if you have a certain disease [lupus]. I'm linking it because within the article there are important remarks for us here on UVP. 

NOTE: Our very own UVP member John C. Dowdy is one of the authors of this paper. 

 

INTRO

 

Halogen lamps emit significant levels of ultraviolet radiation and should be doped or covered with glass prior to use.

Incandescent bulbs emit low-dose ultraviolet radiation.

Fluorescent bulbs emit varying levels of ultraviolet radiation.

Chronic, low-dose UV exposure can cause cumulative skin damage. 

 

Little is known about the potential danger of chronic exposure to indoor lighting sources. In 1990, Diffey elaborated the most common sources of UV radiation (UVR), listing sunlight and cosmetic tanning units first and indoor lamps last [8]. It is becoming increasingly clear, however, that the effects of indoor lamps are more substantial than was once assumed; though the level of UVR emitted is considerably lower than that of the sun [not always], the total exposure time is much longer, which could result in a significant amount of cumulative damage.

 

UVR is typically classified into three major groups based on wavelength: UVA (320–400 nm), UVB (290–320 nm), and UVC (200–290) [9]. Whether or not a particular bulb is considered safe depends on which type of UVR it emits. It is therefore important to understand which wavelengths are considered photobiologically active.

 

HALOGEN LAMPS

 

Unshielded tungsten halogen lamps emit significant levels of UVA, UVB, and even UVC. At a 1 cm distance from the bulb, the UVA and UVB output mirrors that of the sun, while the UVC output far exceeds that of the sun [19]. Several studies have demonstrated that this has serious biological consequences, both from a molecular and clinical perspective.

 

Early evidence illustrated that [unshielded] halogen lamps are genotoxic to bacteria [genotoxic = Describes a poisonous substance which harms an organism by damaging its DNA.]. The UV induces base-pair substitutions and frameshift errors at a rate that surpasses that of natural sunlight [20]. In addition, they are clastogenic/genotoxic to human cells [clastogenic = Describes an agent that can cause breaks in chromosomes that result in the gain, loss, or rearrangements of chromosomal segments].

 

At a distance of 10 cm, a 100 Watt quartz halogen bulb can elicit erythema [reddening of the skin] in just fifteen minutes. Over the course of a lifetime, this represents a 3.4-fold increase in the risk of developing a cutaneous malignancy [26].

 

Luckily, the genotoxic, clastogenic, and carcinogenic effects of halogen lamps can be prevented entirely if the bulb is shielded with a silica glass cover [20, 21, 25, 27].

 

INCANDESCENT BULBS

 

The safety of incandescent bulbs has not been studied extensively, and the results reported in the literature are conflicting. In general, the emission spectrum of an incandescent lamp begins at a discrete point and then increases monotonically. The starting point, however, is under debate. Chignell et al recently demonstrated that a 60 Watt incandescent bulb will begin to emit UV at 375 nm, a point comfortably past the dangerous UVC, UVB, and UVA2 [29]. However, another study [using a more sensitive spectroradiometer] indicates that the emission spectra of incandescent bulbs begin as low as 280 nm, which would be considered a risk to photosensitive patients [28]. Even using the more sensitive spectroradiometer, the level of irradiance is quite low.

 

FLUORESCENT BULBS

 

In 2004, Sayre et al made quantitative measurements of UV emission from fluorescent light bulbs. He tested the bulbs commonly used at home and in the workplace, including unshielded tube lamps and energy-saving compact fluorescent lamps (CFL). His results confirmed the observations made previously. He found that all emitted appreciable levels of UVA and UVB, and several even emitted UVC [28].

 

Recently, Sayre’s group tested several commonly used, commercially available, enveloped compact fluorescent bulbs. They sought to determine which emitted the least UVR and would therefore be safest for photosensitive patients. They found that nearly all of the bulbs emitted UVB and UVA2, despite being covered with a glass envelope. 

 

CUMULATIVE DAMAGE

 

It is apparent that most indoor lamps emit UVR, but the question remains as to whether or not this level of UVR is clinically relevant. While the irradiance is significantly lower than the sun, people spend much more time exposed to light bulbs than they do in direct sunlight. It is therefore important to understand what doses of UV are capable of eliciting damage and to appreciate the cumulative effects of chronic, low-dose UV exposure.

 

The principle of cumulative damage was established in the early eighties.

The damage induced by low-dose UV accumulates with time and eventually becomes clinically apparent.

 

19. Bloom E, Cleaver J, Sayre RM, Maibach HI, Polansky JR. Halogen lamp phototoxicity. Dermatology. 1996;193:207–11. [PubMed] [Google Scholar]

28. Sayre RM, Dowdy JC, Poh-Fitzpatrick M. Dermatological risk of indoor ultraviolet exposure from contemporary lighting sources. Photochem Photobiol. 2004;80:47–51. [PubMed] [Google Scholar]

31. Cole C, Forbes PD, Davies RE, Urbach F. Effect of indoor lighting on normal skin. Ann N Y Acad Sci. 1985;453:305–16. [PubMed] [Google Scholar]

34. Kaidbey KH, Kligman AM. Cumulative effects from repeated exposures to ultraviolet radiation. J Invest Dermatol. 1981;76:352–5. [PubMed] [Google Scholar]

36. Parrish JA, Zaynoun S, Anderson RR. Cumulative effects of repeated subthreshold doses of ultraviolet radiation. J Invest Dermatol. 1981;76:356–8. [PubMed] [Google Scholar]

37. Lavker RM, Gerberick GF, Veres D, Irwin CJ, Kaidbey KH. Cumulative effects from repeated exposures to suberythemal doses of UVB and UVA in human skin. J Am Acad Dermatol. 1995;32:53–62. [PubMed] [Google Scholar]

38. Arbabi L, Gange RW, Parrish JA. Recovery of skin from a single suberythemal dose of ultraviolet radiation. J Invest Dermatol. 1983;81:78–82. [PubMed] [Google Scholar]

 

[Andy Perrin]

Andrea, at a distance of ONE CM from an unshielded halogen lamp, you should be afraid of stuff catching on FIRE. The primary danger isn't so much of cancer as of the severe burns that are likely to result in a few seconds.

[Andrea B.]

Yes, there's that too. 

 

I'm sitting here wondering how one would be able to tell whether a glass covering is "silica glass" ??

[Andy Perrin]

Heh. I mean, most glass cuts even UVB, so it's probably enough to just put any glass in front. The thing is, most of us use such lights on objects that are not skin, and from much larger distances, and usually we just get the reflected light, rather than the direct light, and for only a brief time. All of that tends to attenuate whatever danger there is, I would think? And John Dowdy was talking about long term direct exposure, where there is much greater cumulative risk.

[Andrea B.]

There's another thing to look up! What materials block UVC? 

Polycarbonate, borosilicate, silica glass ?? Let's see some charts.

[dabateman]

1 minute ago, Andrea B. said:

There's another thing to look up! What materials block UVC? 

Most glass will block UVC. Some cheap glass will transmit UVB, but totally block UVC, like k9 equivalent to bk7.

Fused silica, jgs1,jgs2, jgs3 will not block UVC.  But k9 does.

[Andrea B.]

I just read that UVC light will "tan a banana skin" in 15 minutes.

[Andy Perrin]

May I suggest not eating the skin? If you are going to bake something, go with the banana bread instead.

[Fandyus]

8 hours ago, Andy Perrin said:

May I suggest not eating the skin? If you are going to bake something, go with the banana bread instead.

Not to be a devil's advocate, Andy, but I have heard that banana skin is actually edible and it in fact contains more potassium (and I assume other nutrients) than the flesh, consistent with other fruits and vegetables, really. It's just bitter.

[Fandyus]

12 hours ago, dabateman said:

Maybe something, and you can worry about anything. 

But my experience is that its a trival amount of UV. Even the UVA isn't enough for photography. 

Its a great light to stress test a Baader U filter though. You will see the IR leakage and little UV using a hallogen bulb as a light source. 

Some might remember my scare hallogen I have in cut glass.

I have actually used the spotlight for UV photography. I was making some multispectral trichomes of vegetable and fruit cross sections and I took advantage of the fact that I wouldn't have to switch light sources, so the nature of illumination would be consistent between IR, UV and visible.

I might post those eventually. There was not any noticeable leakage either.

[Fandyus]

12 hours ago, Andy Perrin said:

Yeah, you can hardly even do UVA photos without a ton of S8612 on there with a halogen. I don't think there is a minimum safe amount of UVC, so I wouldn't go sitting under it for a long time with no glass, but I doubt ordinary use will hurt you. 

Well, I believe there was a defined maximal daily safe exposure somewhere in the sticky. But it's extremely small. But then, so is the amount of UVC such a lightsource will realistically produce. Someone more well equipped than me should try and measure the actual output, maybe compare it to the cheaply available UVC LEDs.

[Fandyus]

9 hours ago, dabateman said:

Most glass will block UVC. Some cheap glass will transmit UVB, but totally block UVC, like k9 equivalent to bk7.

Fused silica, jgs1,jgs2, jgs3 will not block UVC.  But k9 does.

I must say I would low key like to have some heat resistant glue and such a material, I'd cover the spotlight with it.

[Andy Perrin]

11 hours ago, Fandyus said:

Not to be a devil's advocate, Andy, but I have heard that banana skin is actually edible and it in fact contains more potassium (and I assume other nutrients) than the flesh, consistent with other fruits and vegetables, really. It's just bitter.

Edible is not the same as delicious!