Talk:Ultraviolet
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What is the source of this claim?
- Ultraviolet light is the cause of [skin cancers]? such as melanoma?. The radiation ionises DNA molecules in skin cells, causing mutations which can result in cancerous growths.
I am going to label it an "environmentalist fear" if I can't find any science to back it up. (I'll look myself; I won't be hasty.) -- User:Ed Poor
Ed -- what IS it with you? My goodness. It seems that every time you see something you don't agree with, you pigeonhole it into "beliefs of Liberals" "beliefs of environmentalists" -- as if those are by definition Bad Things. I can't quote any particular scientist, but I'm pretty sure that the AMA and the Dermatology and Oncology boards would agree to a link between UV rays and melanoma. Why do I think this? Because every time I go to the doctor, and especially to the dermatologist, I see pamphlets and posters warning me about not wearing sun block and staying out of the sun when UVA and UVB rays are most intense, in order to minimize the risk of skin cancer. Why don't you just change the bloody thing to "has been linked to skin cancer", rather than pulling your usual namecalling act? JHK
- Are you calling me a "namecaller"? User:Ed Poor
I agree. I'm hardly an environmentalist myself, and would probably apall a greenpeacer if I got into a discussion with them, but I have with my own two hands conducted experiments in which I used UV light to induce mutations in bacteria. To say that it's some sort of environmentalist fearmongering is inane. Bryan Derksen
- (I should mention, though, that it may be reasonable to bring up issues about the magnitude of the risk caused by UV exposure. That's something which is indeed sometimes blown all out of proportion. But please, find some actual numbers before doing that.) Bryan Derksen
Bryan, please add something about bacteria mutations, at least one sentence!
- Alright, but I'll have to dig out some very old notes first. It's something I did back in an undergrad genetics lab. :) Bryan Derksen
Also, I am not disputing the contention that UV can cause cancer. I am only asking for sources. I want to distinguish between:
- scientific sources that have proved something (or at least found it to be highly likely), and
- claims by advocacy groups.
For instance, does UV cause melanoma or non-melanome cancers? How much UV exposure will cause cancer? Is there a threshold over which most people will get a cancer? Or have studies (cite them, please) found an increased rate of cancer at various exposure levels? E.g., double the UV, and the annual cancer rate increases from 100 per million to 180 per million.
Please don't misunderstand. I don't want to suppress science! I only want to label advocacy and distinguish it from science. User:Ed Poor
You're demanding a lot of tedious legwork documenting scientific consensus. Or would you accept "Karen Landau, M.D. (personal communication)" as a source? You say you don't dispute the statement--and then want people to run around proving it anyway. If you're questioning a scientific consensus, the onus is on you to provide citations: studies that (for example) compared different levels of UV exposure and found no increase in cancer. Vicki Rosenzweig
I did some legwork (just before reading the above).
I found a report by WMO, UNEP, NOAA and NASA which said that:
- When high-quality measurements have been made in other areas far from major cities and their associated air pollution, decreases in ozone have regularly been accompanied by increases in UV-B. [1] (http://www.al.noaa.gov/WWWHD/Pubdocs/Assessment98/faq8.html)
However, they did not give any source for this data. They just show a pretty graph. Given the amount of advocacy over this issue, I hesitate to call this "scientific"
The report concedes that:
- From 1979 to 1997, the observed losses in the amount of ozone overhead have totaled about 5-6% for northern midlatitudes in winter and spring, about 3% for northern midlatitudes in summer and fall, and about 5% year round for southern midlatitudes. [2] (http://www.al.noaa.gov/WWWHD/Pubdocs/Assessment98/faq10.html)
Based on my visual estimate of the slope of their graph [], I estimate that this would cause an increase of 1% to 2% in surface UV radiation. This is less than the increase you would get by driving 30 miles closer to the equator. This pales in comparison with flying from Maine to Florida for your summer vacation.
- Ed -- you're working out of context -- again. The quote you claim to object to says UV causes melanoma. Your "evidence" relatesz to the hole in the ozone layer and the increase in UVB rays -- not at all the same thing. Please try to stopy going into articles band making objections based on your a priori beliefs. Articles aren't research projects. Things that are generally accepted, such as the fact that spending lots of time in the sun without protection increases the risk (and some say causes) melanoma, are perfectly acceptable. And if you're going to do legwork, as you call it, please make sure it's relevant. JHK
My comment to Vicky might be on the wrong talk page (elsewhere I said that there is overlap between CFC, ozone, and UV pages). The question I am interested in is whether CFC emissions are a significant cause of cancer. This has a bearing on whether the Montreal Protocol is good or bad, something the wikipedia will not take sides on; but which its readers will want to decide based on information the wikipedia provides.
Are you aware of any scientific evidence supporting the hypothesis that CFC emissions cause ozone depletion, leading to increased surface UV radiation and increased incidence of cancer? If so, please point me to it. I would love to put this info in the wikipedia!
- That's not the point, Ed. That isn't what you mentioned above, and is part of another article. This is just another of your tedious attempts to create debate -- and not the scholarly kind. As I understand wikipedia policy, this is neither a place for original research, nor for the bulletin-type fora you seem to prefer. If anybody had the time to do the research, I'm fairly sure that he could find scientific articles in peer-reviewed journals that support both positions. The fact that the US and other countries all agreed to lower CFC emissions indicates that there is at least some reason to accept that there are links. Please stop threatening to destroy other people's work "unless they can provide proof." This is just a slightly veiled attempt on your part to present the world according to Ed. That is hardly collegial, and certainly a perversion of the Wiki-way. JHK
When there are scientific articles in peer-reviewed journals that support both positions an an issue, why not point these out? I think this is the best thing to do when writing an encyclopedia article about scientific questions which researchers have not settled yet.
We should distinguish between (A) advocacy based on fear and (B) the findings of science. For example, some people advocate mandatory HIV testing, reporting positive results to public health authorities and quarantine -- based on the fear that AIDS will spread unchecked otherwise. The reason for their advocacy is their fear of an AIDS epidemic. On the other hand, there is the question of what causes AIDS and how its method of contagion. These are scientific questions, which can and should be considered separately. Based on the science, as well as other considerations, advocates make public policy recommendations.
Before we debate further, would you please tell me what parts of the above you agree with, Dr. K? User:Ed Poor
- Well there's an unclear question. I'm not sure which part of the "above" I should be looking at. Ed, I'm not here to enter into your debating society. I've already come to the conclusion that discussion with you is fairly meaningless, because I have yet to see one contribution you have made that is from the beginning NPOV and because, whether or not you admit it, every initial stub you post is based on what you call "advocacy" -- although in your book things seem to be either "as Ed sees them (the right way)" and "advocates (liberal, loony left, environmentalist...i.e. wrong according to Ed)." I have yet to see you begin with an empirical approach.
- Moreover, I find it interesting that, when it's science vs. religion, science is wrong in your book (see evolution, etc.), but when you are trying to limit the expression of a consensus viewpoint that you deem "liberal", "environmentalist", "feminist" or whatever "lesser" advocacy, you scream, "show me the scientific proof!" In my religion, hypocrisy is a kind of sin...I guess that the UC doesn't see it that way.
- I also find it interesting that you are always so sure that you are right. I am actually an expert in my fields, and know a whole lot more than the average person in several other fields, mostly because I have the opportunity to discuss things (in modern history, art history, literature, etc.) with people who are experts. Despite the fact that I know my stuff, I usually check and make sure that new articles I produce and edits I make are correct, because I know I am fallible. But then, I live in a world where we have the obligation to prove ourselves right (sometimes despite other opinions), not in the Ed world, where others have an obligation to prove, not only that Ed's views are right or wrong, but that other legitimate views even exist. I don't actually care enough about this stuff to research it. I care about maintaining a high standard of article and using an appropriate scholarly approach. I only involve myself in this nonsense because your approach to contibutions belittles, and often negates, all the intellectual values (like objectivity and honesty) I have held dear for all of my academic life. JHK
I am usually right: it's my outstanding characteristic. One of the things I'm right about is the need for sources to back up claims; that's what distinguishes science from mere advocacy. Scientists feel an obligation to explain their findings, even to share their data. They welcome attempts by other to duplicate their results. Only the dishonest or incompetent ones bristle at the suggestion they may have erred.
Getting back to the article, I'd like to see just a little bit more of the science of UV and cancer: how much UV, what sort of cancer. I personally consider UV dangerous and would never consider lying on a beach all day sunbathing. However, if I lived in Florida I wouldn't move to Alaska just to reduce my UV exposure by 90%.
I'll be happy with the UV-cancer connection when the article provides statistics relating UV levels and the annual number of skin cancer cases. What's so hard about that?
The astronomy paragraph refers to the shielding by the ozone layer, which has not been introduced. Therefore the current order of the paragraph doesn't make sense and I changed it, Ed changed it back, and I change it again. Ed, give a reason for your preferred order of paragraphs. AxelBoldt
Your order is better. I am going to move the CFC-ozone-UV-cancer hypothesis out of the article completely, anyway, and put it where it belongs. But not today. I have to consolidate all the info first (a lot of leg work). User:Ed Poor
- The UV-cancer connection most certainly belongs into this article and should stay here. AxelBoldt
Ed, I did a search on the internet for a site that might help clarify some of the health hazards that ultraviolet radiation can cause. I'm not sure if you've seen this site and discounted the results so far or not, but if you haven't, you might find it of interest.
http://www.ciesin.org/TG/HH/ozhlthhm.html
The problem with science and the public has always been that results that show connections such as you're searching for tends to be published in journals the public rarely reads, and when it does make its way out into the public, non-scientists are the ones doing the interpreting, and of course reading it with their biases. You asked for a connection between CFCs and skin cancer. What you need to actually do is find that CFCs cause depletion in the Ozone layer, which then causes more UV radiation, which causes cancer. I've given one link, after about 3 minutes of checking, maybe I'll look for others at a later date.
Another 'interesting' (to me far more apalling than skin cancer in humans) statement I've seen made, and I think is believed by many Marine Biology folks, is that all coral reefs in the world will be gone in 50 years due to increased UV levels. This while arguments continue as to whether scientists have proof or just correlations at the moment.
For another case which makes me believe that caution over convenience when science shows a possible correlation, should be the order of the day is the Pfisteria outbreaks that occurred in NC. I won't go into huge detail, but you might find it interesting Ed... In NC and MD, Pfisteria outbreaks both occurred around the same time. In MD, it only took a few hundred fish killed with open sores and a handful of fishermen coming down with neurological symptoms for the state government to jump in on a water cleansing program _while_ the science was still going on. In NC, it took millions of dead fish over a few years, and hundreds of people with neurological symptoms (some to the extent where brilliant scientists could no longer count, and people couldn't remember what they were beginning to say at the start of their sentences) before the government even admitted there might be a problem.
I realize it's not the goal of the Wikipedia to put forth ideas in order to change the way society handles CFCs or other potentially harmful items, but the thought of no more coral reefs in 50 or so year makes me much less sympathetic to those who have the attitude of "science jumps the gun, all they have is theories not proofs, let's wait and see further evidence first." Rgamble
Ed, take a look at this link. It's within the same page that I mentioned above. You said you wanted a scientific paper that discussed the matter. Here you go:
http://www.ciesin.org/docs/001-503/001-503.html
There's another article or two that aren't online, but have their references listed, so you can go check them out.
Scientific American has a good article for the layperson at,
http://www.sciam.com/0996issue/0796leffell.html
to which I refer interested parties. I also have some observations on the above debate which I believe belong in user talk:Ed Poor and so am putting them there.
Anyway ...
The article is presently, to my mind, unclear:
- The major component of the sun's light is UV-B, but because of absorption in the atmosphere's ozone layer, 99% of the ultraviolet light that reaches the Earth's surface is UV-A.
The peak of the sun's energy is in middle of the visible spectrum (I even did a Wien's law calculation to check). It may be that the majority of the sun's ultraviolet emission is in UV-B (though looking at the blackbody curve I have my doubts about that as well), but the wording "major component of the sun's light" suggests that the majority of the sun's total EM emission is in the UV-B band, which I'm almost certain isn't correct. I haven't changed the article because my brain's melting at the moment and I'm not sure I haven't missed something, but I just wanted to flag it up.Bth
- I think you're right, that paragraph is incorrect. In fact, it's wrong two ways: Not only is the peak solar emission in the visible (~580 nm), but also there's much more UV-A than UV-B, and it's mostly 'UV-B that gets absorbed by the atmosphere (see [3] (http://www.phys.ksu.edu/gene/e1f2.html)).
- Definitely needs changing. DrBob
- Done.--Bth
Why is this at ultraviolet instead of ultraviolet radiation? I would think if somebody wanted to shorten the name, they would just use UV. Pizza Puzzle
I made a change to this article yesterday, before I knew about this talk page. (I'm pretty new to Wikipedia.) Having now read this discussion, I'm wondering why some of the references discussed here aren't mentioned in the article. Is my lonely reference inappropriate? I certainly don't want to give the impression that UV radiation has only positive effects on human health! If it's OK, what's the right way to do internal footnotes (i.e. a little label '[n]' that links to the References section of the article)? I was trying to follow the Proposed Citation Style in Cite your sources, but maybe that's not the right format. Thanks, Mignon 18:47, 31 Dec 2003 (UTC)
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Ultraviolet as a color
Do you know of any way to modify our eyes so that ultraviolet is visible to us as a color?? This should be known by 2100.
- Sure -- use an instrument that translates UV into colors we can see, perhaps in the form of goggles if you want something wearable. Modifying eyeballs themselves to be UV-sensitive isn't impossible theoretically, but it's a huge can of worms since it would require changing our brains as well to make sense of the information. It seems likely to me that if we ever acquire the technology to do that, mere ultravision would be one of the least of the useful applications. (By the way, why 2100 in particular? And why ultravision, for that matter? I'm genuinely curious about your interest.)
- I doubt you'd need to change your brain to make sense of the information. I would think the easiest method to accomplish this would be to simply genetically modify the DNA which codes for the manufacture of the rhodopsin molecules in the retina's cone cells to be a slightly different shape so they are sensitive to UV light. Say for example you do this to the blue light detecting cones in the eye, the brain would simply process UV light then as "blue", to be sure, you'd see a much different world as percieved colors would be all wrong, but it would work I think.--Deglr6328 23:24, 12 Aug 2004 (UTC)
- Blue cones are already somewhat sensitive to UV light (at near-visible wavelengths anyway; see cone cell) but the lens and cornea absorb too much below 380 nm for this to be useful. There's a story I've heard of a chemist who had eye surgery which resulted in a much thinner cornea than usual, and afterwards he was able to align UV spectrometers visually, so maybe there are people around with "ultravision" already. -- DrBob 23:36, 12 Aug 2004 (UTC)
- Hmmm, interesting thoughts. :o) Incidentally, I have also heard of the early discoverers/tinkerers of X-rays claiming that when they placed a closed eye in front of an X-ray tube they were able to percieve a faint blue/purple glow, directly seeing the X-rays. I have to say that I don't find this altogether implausable, and I've contemplated adding it to the X-rays article but I can't find where I originally read it and I need to know if it was reputable or not.--Deglr6328 19:53, 14 Aug 2004 (UTC)
Does UV exposure cause Melanoma?
The notion that UV exposure causes "skin cancer" seems well supported by the fact that we see basal and squamous cell skin cancers in areas where there is the chronic skin damage, especially sun-related damage.
There is not good evidence at all that UV exposure causes melanoma, though, which is the most deadly of the skin cancers, although there is a widespread acceptance among the medical profession that it does. This is really an unupported belief, and the only evidence is epidemiologic: melanoma is more common near the equator. However melanoma is not very related to sun-exposed areas of skin, and one has to propose that sun exposure somehow alters the immune system to create cancers distal to the area of the body exposed to sun. This is sort of a hypothesis to support a hypothesis, and not very convincing. Nevertheless, the UV-Melanoma dogma is deeply ingrained, and is not likely to go away soon just because there is no evidence to support it. If any of your medical buddies insists that UV exposure causes melanoma, ask them whether or not these lethal skin cancers are most commonly found in the most sun-exposed areas of the body. If they don't have a cogent reply they are probably just parroting what they have been taught.
disputed
"A black light is a lamp emitting only UV light and no visible light."
- If that's true, then there are no black lights. Or are cameras just picking up on UV and converting it to fuschia and violet? lysdexia 03:43, 22 Nov 2004 (UTC)
- Changed this. Better now.--Deglr6328 06:41, 22 Nov 2004 (UTC)
"A UV flame radiates in the 185 to 245 nanometre (1850 to 2450 angstrom) range."
- What's the context? UV is wider than that. Where are these UV flames? lysdexia 03:55, 22 Nov 2004 (UTC)
UV and Sunburn
In the paragraph, Health effects, of ultraviolet article, it mentions "In general, UVA is the least harmful, but can contribute to the aging of skin, DNA damage and possibly skin cancer. It penetrates deeply and does not cause sunburn.". But in the sunscreen article, it mentions "The best sunscreens block both UV-A and UV-B rays, both of which can cause sunburn.".
Would anyone be kind to tell me which one is true?
- The first is true, if you define sunburn as visible damage. I fixed the second article. --Heron 08:43, 4 Jun 2005 (UTC)
Ultrapink light
I recently took a picture of my black light with my digital camera. Normaly, when you look at my light, it is purple, but in my digital camera's photo, it was pink. Also, on a side note, in the photo, I was wearing a white shirt which made it glow. It glowed the same blue in both my eyes and the photo, yet the black light was pink. Why?
- The colored filters used in the Bayer mask of the digicam's ccd do not have the same optical properties as do the rhodopsin molecules in your eye. The CCD is somewhat sensitive to UV and the colored filters of the mask in front of it behave nonintuitively outside the visible spectrum. In this case the red filter was obviously more transparent to the UV than the green and blue filter materials thus making the camera "think" there's more red light coming from the black light and giving it a pink hue. The reason your shirt is the same color in the photo and to your eye is simple. The cotton in your shirt was fluorescing, it was only emitting blue light, not UV, and therefore the camera has no trouble correctly rendering it. If you have an electric stove, turn it on and let the coil heat up, then turn it off and switch the room lights off. Wait till the coil is no longer glowing very brightly and take a picture(no flash!), if your camera lacks a proper IR filter you will see a neat effect. --Deglr6328 01:26, 3 Jun 2005 (UTC)
- What a nice reply! Maybe the anonymous poster of the question could attach the picture? I'm curious to see it. Common Man 05:51, 3 Jun 2005 (UTC)
- Thanks for the answer. I'll paste a picture tomorrow. 6/3/05
- Sorry, but I can't figure out how to edit the page correctly, so I will just give you the html to the image. http://en.wikipedia.org/wiki/Image:DSCN1187.JPG
