[心得] 日曬助曬安全性

看板MuscleBeach (健身)作者xzcvb (再拼一下)時間16年前 (2009/09/18 18:55)推噓2(2推 0噓 0→)

留言2則, 2人參與討論串1/1

上回有篇post也是有關日曬，很抱歉我分享的內容有一些錯誤，已經編輯予以更正。底下我分享一些整理基礎知識、名詞介紹、以及個人認知下的簡單建議. 有所不足的請給我建議或更正、補充。 1. 認識紫外線 http://en.wikipedia.org/wiki/Ultraviolet 這太基礎不贅述。有必要再予以補充說明。 2. 紫外光致黑機制 2.1 UVA 和 UVB的作用引用 http://teenhealth.about.com/od/bodyimage/a/howtanninghappens.htm How UV Rays Cause a Tan 紫外線如何導致曬黑 UV rays cause tanning by the way they affect the melanin in our skin. Melanin is a pigment in our skin and is what gives our skin its color. * UVA causes a tan by oxidating the melanin. Essentially, the melanin undergoes a chemical reaction after being exposed to UVA, causing it to become darker. When the melanin looks darker, the skin itself looks tanned and dark. 節譯: UVA會導致麥拉寧黑色素的氧化，而加深它的顏色. * UVB causes a tan in a different method. UVB causes an increase in production of melanin in the skin and other changes to the cells that the melanin is stored in. These UVB effects cause the skin to become darker or tanned. 節譯: UVB不同, UVB會促進黑素細胞產生麥拉寧黑色素. 提高麥拉寧黑色素儲存量. UVB也會造成麥拉寧黑色素顏色加深. 2.2 DNA的傷害引用 http://en.wikipedia.org/wiki/Melanogenesis Since the action spectrum of sunburn and melanogenesis are virtually identical, it is assumed that they are induced by the same mechanism.[8] The agreement of the action spectrum with the absorption spectrum of DNA points towards the formation of cyclobutane pyrimidine dimers (direct DNA damage). The acronym for cyclobutane pyrimidine dimers is CPDs. 節譯: 黑素生成(melanogenesis)與曬傷其作用的波段是相同的，故一般假設有相同的機制。曬黑作用區段與DNA吸收光譜的一致，指出它是來自DNA的直接傷害 (CPD) ref: Nita Agar; Antony R. Young (2005). "Review: Melanogenesis: a photoprotective response to DNA damage?". Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 571 (1-2): 121–132. 解釋: DNA傷害之後細胞藉由甲硫氨酸和葉酸等物質有一定的修補機制。不過這邊就要注意了：假如一個促進曬黑的方式，是藉由增加DNA傷害而達成，那可以說是一個不好的方法。因為越多DNA傷害，意謂著細胞病變機率越高。目前理解, DNA傷害是皮膚曬黑一個必經的機制。 3. 有人根據UVA & UVB 的特性擬定了日曬策略《UVB to build a tan. UVA to maintain it》 http://www.tan-biz.co.uk/fileadmin/all/tanbiz/UK/downloads/2007/01_2007/ TBUK0701_55_web.pdf UVB to build a tan You only need a little UVB to stimulate the melanin producing cells (melanocytes) into producing extra melanin ‘parcels’. It must be enough to trigger melanin production but no more; any more than this will simply result in cell damage (erythema, or sunburn). Initially, after winter, pale skinned persons don’t need any UVA in their first few sessions because the priority here is to start up the little melanin factories (melanocytes) in the skin and this takes a few days. Any UVA they do receive is wasted – it produces very little effect (there is not enough melanin around after winter in skin type 2 persons, particularly) and as a result is absorbed by the wrong molecules (not melanin, which is largely absent until after the first few sessions, but more vulnerable and unprotected parts of the skin). This causes free radical damage and may affect cell DNA temporarily, or even permanently. There appears to be no reason why we could not use a theoretical‘Type 3’ lamp which produced only UVB for the first couple of sessions. This would concentrate on making melanin that later sessions could then brown using mainly or purely UVA. UVB is needed to build a tan by creating more melanin in the first place. 節譯: 靠UVB來建立曬黑的基礎你只需要一點 UVB 的劑量來刺激黑色素細胞進入多量的麥拉寧生產狀態. UVB必需要夠多來引發麥拉寧生產，但是不需要更多。更多的劑量只會造成細胞傷害。 (紅班或曬傷) 在初始階段，或剛過冬天，蒼白皮膚的人前幾次曬不需要UVA，因為此時優先的事情是啟動皮膚上的小小麥拉寧工廠讓它開始生產。這將要花費數天。此時UVA的照射是浪費的，它只產生很少的作用 (因為皮膚中沒有足夠的麥拉寧)。結果UVA將由不是預期中的分子吸收，因而引起自由基或是暫時甚至永久影響細胞的DNA. (後段廣告自家商品就不翻譯了) UVA to maintain a tan Once melanin ‘parcels’ start to be produced by the melanocytes after being triggered by UVB(2), they migrate into the upper layers of skin where they spread out to cover the DNA-containing cell nuclei and so protect them (like umbrellas, or sun shades!). At this stage the melanin is white (not exactly, but very pale anyway) not brown. In order to turn brown it needs to be bombarded with UVA, which is where our high intensity UVA tanning lamps come in. The higher the intensity of UVA the darker the tan in shorter session times. To get this dark with lower intensities of UVA you need a longer session time – and this may be ideally suitable for the beauty sector. Longer session times are also more efficient at browning melanin and it is possible to get a better result with less cell damage from a longer, weaker session. Once the melanin production is kick-started by UVB, you only need a little UVB to trigger continued production so it makes sense to concentrate more on UVA once the tan starts to appear. Alternating two or three UVA sessions to one UVB session could be a way of deepening a tan using type 3 intensity tanning lamps. You might, say, devote one sunbed out of three, four, or five, to exclusively using UVB lamps and the rest to UVA. UVA is needed to ‘brown’ or maintain a tan. A good tan needs both UVB and UVA, but in differing amounts at different times and not necessarily together. 節譯: 靠UVA來維持深膚色一旦UVB照射引發黑色素細胞開始生產麥拉寧，這些麥拉寧被傳送到皮膚的上層，並且散布開並且蓋住含有DNA細胞核的細胞 (像一把傘或是遮陽)。在這個階段麥拉寧仍然是白色的 (嚴格講不是白色, 但是是非常淺色的) 而非褐色。要把它轉為褐色，它需要UVA的 '轟炸'. UVA強度越高所需的時間越短，如果想靠低強度的UVA光源你會需要曬較長的時間。較長的曬膚時間，對於加深麥拉寧的顏色也較有效率；這種低強度-長時間的曬膚結果較好，細胞傷害較小。一旦UVB照射啟動麥拉寧製造，你只需要少量的UVB來維持它持續製造。所以一旦膚色加深了專注在UVA是合理的。 However, if the best guide to safety is the composition of natural sunlight, then we had best stick to mainly UVA with a little UVB. It’s not an exact match, but the closest in terms of practical application in a commercial setting. Clearly, there is stillsome way to go with this infant subject but it may hold the future of tanning. 4. 助曬 tanning activator http://en.wikipedia.org/wiki/Tanning_activator 這個wiki解說了目前已知助曬的機制. Mechanism of tanning activators The increased production of melanin is the reaction of the skin to UVB-induced direct DNA damage.[6] Several substances are known to increase the amount of direct DNA damage (thymine dimers). In order to produce this action they have to penetrate into the skin, and this is in contrast to the assumptions which are made by those who endorse sunscreen use (see sunscreen controversy). 節譯: 麥拉寧黑色素的產生增加，是來自皮膚對於UVB引發的DNA傷害。有數種化物是我們已經知道可以增進DNA傷害.(thymine dimers 是一種DNA傷害.) The tanning activator coumarin is known to induce thymine dimers (cyclobutane pyrimidine dimers). 節譯: 助曬成份香豆素coumarin 已知是會造成CPD傷害的。解說: 香豆素的這種作用，是一種光敏性。 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 122.120.32.167 ※ 編輯: xzcvb 來自: 122.120.33.139 (09/19 13:27)

[心得] 日曬 助曬 安全性

[心得] 日曬助曬安全性