24 votes
Accepted

Can UV radiation be safe for the skin?

You're talking about long-wave UV, or UV-A radiation. In the 80s, experts claimed that this was a safe wavelength. Protection against UV-A was not part of sunscreen in the early days. Consequently, UV-...
S Pr's user avatar
  • 6,222
17 votes

Why does UV radiation from the Sun cause skin cancer?

Rather than 'breaks' caused by high energy radiation, UV radiation causes chemical modifications of the bases ('letters') that make up DNA. There are four bases in the DNA alphabet abbreviated to A,T,...
mimat's user avatar
  • 1,425
15 votes

Why does UV radiation from the Sun cause skin cancer?

There are very many photochemical reactions: Up to 50–100 mutagenic reactions on DNA per second might occur in a skin cell during exposure to sunlight, but are usually corrected within seconds by ...
bandybabboon's user avatar
  • 10.4k
9 votes

How lethal is high dose UV?

The answer is easier than you think. Have you ever had a sunburn so bad that it causes blisters? (I have, as a teen falling asleep on the beach.) Those sunburns are called second degree sunburns. With ...
anongoodnurse's user avatar
7 votes

Can UV radiation be safe for the skin?

There are (at least) two sides to this story. One is direct DNA damage being caused by UV-B light which happens to have photons with just the right amount of energy to interact with thymine. This has ...
Damon's user avatar
  • 259
5 votes
Accepted

Why does UVA penetrate deeper than UVB, though it's weaker?

Our skin contains quite a lot of water and I think this is answers the question: The absorption of UV light by this water goes drastically up when you shift to shorter wavelengts with a minimum ...
Chris's user avatar
  • 51.6k
4 votes

Spectroscopic methods for quantifying peptides/proteins with or without Tryptophan or Tyrosine content

I think it would not be a problem if you use NanoDrop for your measurements. But there are better options if using UV-Vis is not a strict rule. Alternatively, Qubit itself doesn't have any issues ...
cc12amu's user avatar
  • 126
3 votes
Accepted

If my sunglasses provide "100% UVA/UVB Protection" why can't look directly at the sun?

The damage to your eye does not only come from UV exposure, but also from infrared (IR) radiation. Your eye contains a lens that focuses the incoming rays to a narrow point. This point would get very ...
adjan's user avatar
  • 2,106
2 votes

Could being exposed to excess UV in the arctic lead to a human eye color change? If so, what is the mechanism?

It's a four year old question and so far nothing definitive, but the September 30, 2022 BBC Future article How our eyes can change colour throughout our lives includes the following quotes from David ...
uhoh's user avatar
  • 5,486
2 votes

Why does UV radiation from the Sun cause skin cancer?

Physics/Chemistry aside, as @mimat and @aliential awesomely explained, it's always good to keep in mind that cancer, in general, is a statistics game, in the sense that at any time, there's a cell ...
As Aves's user avatar
  • 21
1 vote

How lethal is high dose UV?

It depends on the wavelength. This paper1 provides the numbers: This study was conducted to determine the toxicological effects of different wavelengths (250, 270, 290, and 310 nm) and doses of UV ...
Nilay Ghosh's user avatar
  • 1,214
1 vote

How lethal is high dose UV?

You wouldn't get something like radiation sickness but something can be so unhealthy that can then lead to increased mortality. Whether or not something kills you is the lowest bar that can be set for ...
DKNguyen's user avatar
  • 920
1 vote

Could life protect itself from ultraviolet radiation?

Preamble The original question asked about fair assumptions, but addressed conviction rather than scientific evidence. This site primarily exists to address biological questions that can be answered ...
David's user avatar
  • 25.7k
1 vote

Which is more efficient as a germicide: UVC, Ozone or combination and why?

Your question contains the word "efficient". The most efficient method is the one with achieves the goal with the minimum of effort or disadvantages. And that totally depends on what you want to do ...
akraf's user avatar
  • 382
1 vote
Accepted

How far can free radicals from UV radiation diffuse through the skin?

The life of the radicals decides how far they move. This paper https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4310837/#!po=6.92308 has a table of half lives of radicals, the longest lasting ones (the ...
Polypipe Wrangler's user avatar
1 vote
Accepted

What is the simplest way to demonstrate the germicidal property of UV light?

You can make homemade bacterial growth medium. https://www.madaboutscience.com.au/shop/science-extra/post/grow-bacteria-on-homemade-agar-plates/ Basically it is just nutrient jello: beef stock, ...
Willk's user avatar
  • 2,964
1 vote

Why do redheads tend to sunburn more easily?

You should have a look at wikipedia > melanin. Melanin is a broad term for a group of natural pigments found in most organisms. [..] Melanin is an effective absorber of light; the pigment is able ...
Remi.b's user avatar
  • 68.1k
1 vote

Using UV to kill bacteria in shoes

The wavelength of UV-C most effective at provoking mutagenesis in DNA is 260 nm, which has been shown to kill Cryptosporidium parvum at doses below 10 mJ/sq cm. http://www.ncbi.nlm.nih.gov/pubmed/...
pkScary's user avatar
  • 11
1 vote

How does UV light damage the DNA when the chromosomes are deep inside the cell?

UV Rays kill the cells by damaging the DNA. UV lights do not disrupt the cell membrane. If a cell is exposed to UV light, it creates THYMINE dimers (bond). Thymine dimers are the actual disruption in ...
Arunchunaivendan's user avatar

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