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Study of Cellphone Risks Finds 'Some Evidence' of Link to Cancer, at Least in Male Rats
For decades, health experts have struggled to determine whether or not cellphones can cause cancer. On Thursday, a federal agency released the final results of what experts call the world's largest and most costly experiment to look into the question. The study originated in the Clinton administration, cost $30 million and involved some 3,000 rodents.
The experiment, by the National Toxicology Program, found positive but relatively modest evidence that radio waves from some types of cellphones could raise the risk that male rats develop brain cancer. "We believe that the link between radio-frequency radiation and tumors in male rats is real," John Bucher, a senior scientist at the National Toxicology Program, said in a statement.
But he cautioned that the exposure levels and durations were far greater than what people typically encounter, and thus cannot "be compared directly to the exposure that humans experience." Moreover, the rat study examined the effects of a radio frequency associated with an early generation of cellphone technology, one that fell out of routine use years ago. Any concerns arising from the study thus would seem to apply mainly to early adopters who used those bygone devices, not to users of current models.
[...] The rats were exposed to radiation at a frequency of 900 megahertz — typical of the second generation of cellphones that prevailed in the 1990s, when the study was first conceived. Current cellphones represent a fourth generation, known as 4G, and 5G phones are expected to debut around 2020. They employ much higher frequencies, and these radio waves are far less successful at penetrating the bodies of humans and rats, scientists say.
Previously: Major Cell Phone Radiation Study Reignites Cancer Questions
First Clear Evidence Cell Phone Radiation Can Cause Cancer In Rats
Related: Dim-Bulb Politician Wants Warning on Cell Phones
California Issues Warning Over Cellphones; Study Links Non-Ionizing Radiation to Miscarriage
Mill Valley, California Blocks 5G Over Health Concerns
(Score: 0) by Anonymous Coward on Saturday November 03 2018, @04:12PM (14 children)
I love when these physics/chem 101 calculations are used to debunk medical claims. Who said ionizing radiation is necessary to lead to dna copy errors? Only you and other pseudoskeptics.
(Score: 0) by Anonymous Coward on Saturday November 03 2018, @04:39PM (13 children)
(Score: 0) by Anonymous Coward on Saturday November 03 2018, @04:44PM (9 children)
In general, just disrupting hydrogen bonds.
(Score: 0) by Anonymous Coward on Saturday November 03 2018, @04:57PM (8 children)
Or even van der waals interactions...
(Score: 0) by Anonymous Coward on Saturday November 03 2018, @05:32PM (7 children)
(Score: 0) by Anonymous Coward on Saturday November 03 2018, @06:00PM
1) Different frequencies have different effects on different molecules.
2) Who said it isnt happening?
(Score: 3, Interesting) by rleigh on Saturday November 03 2018, @09:49PM (5 children)
High frequency radiation in the UV-visible-IR range is largely non-penetrating. UV can barely penetrate more than a few hundred microns. IR can penetrate a millimetre or so before it rapidly falls off in intensity. Microwaves can penetrate much deeper.
Visible light is dangerous to us. Phototoxicity through free radical generation is a problem. We have evolved elaborate molecular mechanisms to cope with this by mitigating and repairing damage, as well as specialised tissue structures in our skin to cope with constant exposure (squamous epithelium and melanocytes). Our internals have not evolved to deal with it at all.
Microwaves are usually not ionising but they do cause localised heating. And they can penetrate and heat at greater depths (several centimetres).
(Score: 0) by Anonymous Coward on Sunday November 04 2018, @03:40PM (4 children)
True
It should also be noted that our bodies are often subject to temperature changes on a regular basis. Our bodies regulate temperature. We wear jackets when we get cold and we take them off when it's hot. Our body temperature still varies slightly from time to time. When we're sick the temperature may rise. If we're outside when it's cold our temperature may fall even though our bodies will counteract the effect to some extent.
"DNA that consists entirely of AT base pairs melts at about 70° and DNA that has only G/C base pairs melts at over 100°."
(Celsius)
https://sandwalk.blogspot.com/2007/12/dna-denaturation-and-renaturation-and.html [blogspot.com]
Body temperature is about 37 degrees Celsius. To what extent can a cell phone cause enough localized heating to break base pairs?
https://sandwalk.blogspot.com/2007/12/dna-denaturation-and-renaturation-and.html [blogspot.com]
I found this interesting though it doesn't directly relate to your comment, I figure I'll post it here.
The temperature at which the DNA strands are half denatured, meaning half double-stranded, half single-stranded, is called the melting temperature(Tm). The amount of strand separation, or melting, is measured by the absorbance of the DNA solution at 260nm. Nucleic acids absorb light at this wavelength because of the electronic structure in their bases, but when two strands of DNA come together, the close proximity of the bases in the two strands quenches some of this absorbance. When the two strands separate, this quenching disappears and the absorbance rises 30%-40%.This is called Hyperchromicity. The Hypochromic effect is the effect of stacked bases in a double helix absorbing less ultra-violet light.
...
While the ratio of G to C and A to T in an organism's DNA is fixed, the GC content (percentage of G +C) can vary considerably from one DNA to another. The percentage of GC content of DNA has a significant effect on its Tm."
https://en.wikibooks.org/wiki/Structural_Biochemistry/Nucleic_Acid/DNA/DNA_Denaturation [wikibooks.org]
I'm not saying that cell phones are harmless. I'm actually overly paranoid about cell phone radiation myself. I just figure I'll bring this up for discussion.
(Score: 2) by rleigh on Sunday November 04 2018, @05:16PM
Yep, this is all true. We paid a lot of attention to melting points and GC content when designing PCR primers. However, when considering these temperatures, do bear in mind that it's the temperature to separate the entire strand with no possibility of random reassociation. It might only require melting 20 bases or so to have a functional effect, and that can take place at a significantly lower temperature. It's happening all the time randomly at the scale of a few base pairs at normal temperatures. It only requires a little push to expand this to a few more base pairs. It would only require a very small heating effect at the scale of a few cubic micrometres or less to do this, and microwaves could I believe do exactly that.
One really cool thing is that organisms which exist at higher temperatures, e.g. hydrothermal vents, have evolved higher GC content to stabilise the DNA under "normal" conditions for them.
(Score: 0) by Anonymous Coward on Sunday November 04 2018, @05:32PM (2 children)
The point is that in principle all you need is to disrupt some important but weak interaction at a crucial moment (base pairing during dna synthesis, chromosome alignment during mitosis) to get an increase in cancer.
(Score: 0) by Anonymous Coward on Tuesday November 06 2018, @01:32PM (1 child)
and you raise a valid point. Like I said, I myself am paranoid about cell phones and I believe I am overly paranoid.
But the counterargument is that if such slight variations in temperature can have such a profound effect then why aren't we worried about getting cancer every time we stand next to the heater. Or every time we go outside in the sun during summer when it's hot. We might as well invest more to ensure that we are constantly in an isothermal environment because surely standing next to the heater will cause me more temperature fluctuations than using my cell phone. I can probably measure the temperature fluctuations on my body of standing next to the heater with an actual thermometer used to detect fevers. I would need a highly sensitive, expensive thermometer to detect temperature differences to my body by using my cell phone. There are a million environmental factors that affect my body temperature far more than cell phones that I'm exposed to on a daily basis. Every time the wind blows it probably causes me temperature fluctuations more measurable than those caused by using my cell phones.
(Score: 0) by Anonymous Coward on Tuesday November 06 2018, @01:36PM
Maybe your body's epidermis can handle infrared heat and prepare for incoming temperature changes due to infrared, but it can't handle the deep penetration of powerful radio waves that slowly heat up cells from the inside.
That sounded science-y.
(Score: 1, Interesting) by Anonymous Coward on Saturday November 03 2018, @05:19PM
And then there is the whole world of epigenetics. DNA only acts through the proteins that it codes. Epigenetic effects change how and when the DNA sequence is read into proteins. So no need to damage the DNA to cause effects.
(Score: 3, Insightful) by rleigh on Saturday November 03 2018, @09:25PM (1 child)
Well, for starters, consider this. DNA is a double-stranded helix, where the paired bases on each helix interact weakly via hydrogen bonds. Two for A-T, three for G-C pairings. It doesn't take much energy to disrupt that pairing and "melt" the strands. Now, the molecules are huge, and the cumulative strength from all the pairs in total results in a very stable structure. However, it's easy to disrupt a small bit and create a single-stranded "bubble". This exposes the bases in that area to the cellular machinery for transcription. That site might be a promoter, enhancer, repressor, or other regulatory sequence and trigger some action such as transcription of a particular gene, or repression of another. Or it might displace some regulatory RNA sequence. Cell signalling is very complex, but this could ultimately affect some key signalling pathway, and potentially promote unregulated division. Note that terahertz radiation has been shown to "unzip" DNA. Microwave radiation can cause localised heating which can then trigger melting.
Protein structures are also subject to delicate thermodynamic equilibria, where temperature increases could potentially change the structure stability, leading to conformational changes and disruption or stabilisation of protein-protein or protein-ligand interactions. Suppose that molecule is a tumour suppressor, and you affect its function.
Note that none of this relies on ionising radiation breaking chemical bonds. It's simply a local shift in the thermodynamic equilibrium. The chances of a single event being disruptive are low. It's all ultimately down to probability, where increased exposure makes it more probable an undesirable event will occur.
(I do have a PhD in biology.)
(Score: 0) by Anonymous Coward on Sunday November 04 2018, @04:11PM
Thanks. Reading comments above had me frustrated and ready to post this, but I would've been much less concise than you. Appreciate your accuracy and even-headedness.
Whenever someone says "oh it's not ionizing so it's safe" it boggles my mind. There are lots of molecules that are photosensitive, including in humans, and all kinds of chemical and kinetic events can lead to different conditions of DNA,RNA,methylation,etc.