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Comment by colordrops | Hacker News Reader

One thing I could never understand is this apparent contradiction: there is this trope that non-ionizing radiation doesn't cause cancer, which is repeated in this article, but it can also heat up and burn tissue, which can definitely cause cancer. So which is it? I understand that non-ionizing radiation doesn't directly create cancer, but can't it indirectly cause cancer?

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Any source that radiates low energy photons at sufficiently high flux density will inevitably cause tissue damage. For example, green light from a 5 mW laser is fairly safe, but green light will cause serious damage from a 20 W laser source.

The comparison between ionising and non-ionising radiation is really about Watts per photon. Low energy photons need significantly more flux density (i.e. brighter) to create the same amount of damage as high energy photons. So the trope is really about you don't need a very bright ionising radiation source to give you cancer.

Your comment is glossing over the fact that high energy photons cause damage through a different mechanism not available to lower energy photons. A higher dose of lower energy photons may cause damage still, but not in the same way

Ionizing means that a photon has enough energy to eject an electron from an atom, ionizing it. This can disrupt chemical bonds, hence the direct damage to proteins, DNA, etc.

According to this it's rare

https://pubmed.ncbi.nlm.nih.gov/18176744

And according to the below there is evidence to suggest it can cause protein degradation and also DNA damage. That damage that tends to result simply in outright death rather than mutations which could cause cancer

https://pubmed.ncbi.nlm.nih.gov/19587691/

There is evidence that non-ionizing radiation can cause cancer.

https://www.nih.gov/news-events/news-releases/high-exposure-...

And weirdly:

> He also noted the unexpected finding of longer lifespans among the exposed male rats. “This may be explained by an observed decrease in chronic kidney problems that are often the cause of death in older rats,” Wyde said.

Ionizing radiation can cause cancer directly by damaging the DNA of a cell creating mutations thus increasing the probability of cancer. Heat is just heat. In extreme cases, it can cause severe burns. Cancers caused by burns and wounds are rare but possible. I think you may have factored in UV radiation that we receive from the sun, but this is something else: higher energy UV rays are ionizing radiation.

Any single particle of ionizing radiation can cause damage; there's no threshold. For non-ionizing radiation to cause damage it needs to exceed a threshold.

Right, that's what I mean by "create" vs "cause".

Since when does heating up and burning tissue cause cancer? If that were true you'd expect burns to skin to have a higher risk of cancer.

It’s also not really relevant to the normal situation where you are exposed to low levels of non-ionizing radiation through radio waves at energy levels much lower than enough to generate heat, let along burning. If your phone is causing burning, you have an bigger, immediate problem beyond radiation exposure.

Burning (damaging) a cell can cause damage at the genetic level. If the cell divides you can get mutations. Any cellular damage can increase the risk of cancer via this series of events. Animal bodies have mechanisms to identify and eliminate aberrant cells, which is not 100% effective. This is biology 101.

> If that were true you'd expect burns to skin to have a higher risk of cancer.

There are a number of studies still trying to figure it out, since there is a high number of cases reported, despite evidence showing that it shouldn't increase. Some papers:

https://www.sciencedirect.com/science/article/abs/pii/S03054...

https://www.medicaljournals.se/acta/content/html/10.2340/000...

https://www.jstor.org/stable/20486296

https://burnstrauma.biomedcentral.com/articles/10.1186/s4103...

(from googling)

>> https://www.jstor.org/stable/20486296

Says no evidence of increase of cancer from burns. They also include chemical burns. Another article you linked specifically focuses on chronic immunosuppression.

Chronic inflammation, on the other hand, is well noted to influence cell mutation, so that is probably where the connection, if any, exists.

Genuinely curious, can burning tissue really cause cancer? Like if I put my hand over a fire for too long and get a 3rd degree burn?

A full-thickness burn is going to cause a lot of problems; an increased risk of cancer down the road is likely to be the least of your problems.

That said, inflammation and tumors are surprisingly tightly linked: many tumors co-opt inflammatory pathways, or use them to establish favorable "micro-environments" that allow the cancer to proliferate.

Here's a review about the link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2803035/

“ also heat up and burn tissue, which can definitely cause cancer”

Where do you get that “fact” from? I have never seen any reputable source say that heat, even to the point of tissue damage, has any affect on cancer.

I’m too lazy to Google if this is true, but I recall studies linking drinking hot beverages (tea, coffee) to esophageal cancer, presumably from heat damage.

"Yerba Mate Straw Cancer" are the terms you need.

Seems to be quite a bit of noise about it from various places. No idea whether there is any truth to it though.

Continued inflammation over time has some connections to cancer, but it must happen over a long period of time in order to initiate a cell mutation.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6704802/

No increase of cancer from burn victims:

https://pubmed.ncbi.nlm.nih.gov/18176744/

The chain goes Heat -> Inflammation -> Cancer. It is well known that inflammation causes cancer. It is one of the biggest and often underlooked causes of cancer in obese individuals.

See https://www.google.com/search?q=obesity%20inflammation%20cau...

UVA/UVB radiation definitely causes cancer, and it's non-ionizing.

Wow, true. Interesting mechanisms of action:

https://www.sciencedirect.com/science/article/abs/pii/S09698...

"In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Melanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV radiation." https://en.wikipedia.org/wiki/Melanin

"Radiative relaxation quantum yields for synthetic eumelanin" https://pubmed.ncbi.nlm.nih.gov/15068035/

The key here is its "near ionizing" the mechanism is still based on photon energy for which RF does not have enough.

Near ionizing and up have non thermal effects, RF's much lower photon energy's only known action is thermal which requires orders of magnitude more power to create enough heat to damage DNA.

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