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11 June 2011
Tom Anhalt from Santa Barbara, CA asks:
“It sounds as if some sort of new mechanism for this type of radiation to cause cell damage needs to be identified for the purported link to be real, no?”
Some yet-to-be-discovered mechanism for DNA damage would definitely make the link between cell phone use and brain cancer incidence more plausible. Such a mechanism could establish causation and not just correlation. If there was a strong link between cell phone use and brain cancer incidence (which there is not) one could not distinguish whether cell phone use causes cancer, or whether people who get brain cancer merely tend to use their cell phones more.
I would like to distinguish between two commonly conflated terms:
Mutagen: An agent or stimuli that triggers lasting damages in DNA.
Carcinogen: An agent or stimuli that causes cancer.
Most carcinogens discovered are mutagens, and experiments must be done to determine causality, because testing of potentially harmful agents are not done on humans in civilized society. This can be done in vitro (outside of the body, like a test tube or petri dish) or in vivo (in a living organism, like a mouse).
But not all mutagens are carcinogens. Mutagens are discovered through methods like the Ames Test in bacteria, or the plate assay experiment with human cells in culture in a petri dish.
The Ames Test uses bacteria that have a mutation in their DNA that must be reversed through mutagenesis (a stable change in their DNA) to allow them to grow quickly again. The Ames Test is used in the rapid screening of hundreds of thousands of compounds that we are exposed to. Pretty much anything can be used in an Ames Test, including radiation. There is strong negative data to suggest that the frequencies of radiation from cell phones DO NOT cause mutagenesis and are not mutagens. (1)
A plate assay involves the use of human cells in a petri dish that are allowed to grow to form a monolayer (later one cell deep) completely covering a petri dish. Normal cells tend to stop growing when they have completely covered a dish and are one cell deep. Cancer cells can usually grow more than one cell deep in these conditions. If normal cells are treated with a mutagen, they will often start to grow on top of each other, in a fashion similar to cancer cells. Such cells are then referred to be cancer biologists at “transformed cells.” A cell transformation experiment is another proxy for mutagenesis and carcinogenesis. There is strong negative data to suggest that the frequencies of radiation from cell phones DO NOT cause normal cells to transform into cancer-like cells. (1)
I am merely scratching the surface for the negative data in vitro to suggest that the radiation from cell phones does not trigger cancer. One in vitro experiment does not usually predict accurately what happens in a person, but many, many, many experiments that have the same result using different methods are fairly predictive and accurate.
But, in vitro correlation experiments lack teeth if they do not agree with in vivo correlation studies, like those done on cell phone use and cancer incidence. As discussed in last week’s article, the positive data to support the cancer and cell phone link is paper-thin, skewed at best and probably not real at all. There is also a lot of negative (in vivo) data from very robust studies on cancer incidence and cell phone use that do not show any trend. As outlined here, the ways scientists have detected harmful, cancer-causing stimuli or agents for the last 50 years has not yielded any implication that cell phones can cause cancer.
If cell phones did cause cancer, it would have to be through a completely novel mechanism yet unknown to science. There is a generation of young, creative scientists that would LOVE to sink their teeth into such a discovery, as doing so would most certainly lead to fame and fortune. Trust me, the reason why no in vitro red flags have been found is not because no one is looking. It is in fact quite the contrary: scientists are biased to look extra hard for ANY possible link because it is controversial.
Cell phones could still cause cancer, but the link would either be very small or so small as to pale in comparison to real health risks, like driving while talking on a cell phone.
Given the data, it is of the opinion of this young scientist that cell phones do not cause cancer. This young scientist also wishes that we could put this topic to rest so people can focus on things that have clear and present health risks, like sun exposure, smoking, and operating motor vehicles while on cell phones.
1) The Biology of Cancer by Robert A. Weinberg 2007