Monday, May 5, 2014

iCancer — Are cell phones increasing our risk?

Nobody Likes Cancer . . . But Everybody Likes Cell Phones!

We hear about it everyday. New foods or products are constantly putting us at risk of developing cancer, and what is worse is that many of these claims have very little support behind them. One of the most common theories that preferentially puts our generation at risk is the idea that the cell phones put us at a greater risk of developing cancer. But is this true? One of the biggest problems surrounding this topic is the vide variety of tests and results available within the scientific community. From this most big-name institutions such as the American Cancer Society(ACS) and National Cancer Institute have chosen to say that there is little scientific evidence supporting the claims, whereas others like the World Health Organization choose to list cellular devices as a potential carcinogen on the IARC's 2B list (which is essentially a watch list). Rather than generating more data that is likely to be inconclusive, I have decided to break the argument down on a few different levels in order to reach my own conclusion.
Figure 1: Source, Marion Institute

     We know that cancer develops as a result mutations to our DNA, and a major source of these mutations is damaged DNA that is nor repaired properly. While we have between 25,000 and 30,000 genes only a handful are crucial to developing cancer. DNA damage events can cause proteins responsible for cell cycle control to either lose (tumor suppressors) or gain functions (oncoproteins) thus de-regulating the cell cycle.  We encounter things that damage our DNA everyday, but increased exposure to carcinogens (mutagenic cancer causing agents)  the likelihood that one of those mutations will be in an oncogene or tumor suppressor increases. This is the main reason that we take extreme care when using hazardous chemicals in lab experiments (such as ethidium bromide) most individuals avoid smoking; however a topic that is has become increasingly prevalent in discussions of cancer is that of cell phones and their emissions of electromagnetic radiation as a carcinogen.

Lets Talk About Radiation...

There are many types of radiation, and the image below is intended to provide visual support for how radiation is broken down. We normally think of radiation in terms of its frequency (measured in Hertz, Hz). Generally the higher the frequency the more dangerous it is, but let's take a look at where cellphones end up on the spectrum.
Figure 2: Source — Christina Wood's Physics Notes
As you can see the radiofrequency (RF) radiation (in our case this is where cell phones lie) is one of the lowest on the electromagnetic spectrum. We call this non-ionizing radiation because it has enough energy to cause molecules to vibrate, but not enough to remove electrons (EPA). In fact, we do not even begin to see DNA damage until we reach things like UV light, X–Rays, and Gamma Rays, which we call ionizing radiation (correction...only X-Rays and Gamma Rays are ionizing radiation, however UV radiation does in fact cause direct DNA damage through the formation of thymine dimers) due to the fact that it can break chemical bonds and remove electrons from atoms (EPA). As you can see from figure 3a, ionizing radiation causes direct DNA damage by creating physical blocks to transcription and replication (thymine dimers), and by physically breaking the double stranded DNA.  Normally cells can repair this damage, but if it is not repaired mutations can be introduced. Cell phones do not have enough energy to cause direct DNA damage (American Cancer Society). Clearly we have known about this  EM spectrum for many years, so what has the scientific community buzzing? One of the major theories behind the cellphones and cancer is rooted in non-ionizing radiation's ability to physically heat up cells. This means that the RF radiation does not directly cause the DNA damage but instead provides an environment that stimulates DNA damage events (figure 3b)

Figure 3: The Damaging Effects of Radiation
(correction: UV radiation is not ionizing radiation, but it does cause direct DNA damage via the process diagrammed above)

To the Science...Heating up the Debate!

Many people accept the fact that RF radiation is incapable of causing direct DNA damage (figure 3a), but others believe that damage is caused by the RF's ability to heat up the body's tissue (figure 3b). Similar to how microwaves function to use non-ionizing radiation to heat up popcorn or leftovers, some fear that if a cell phone emitted a high frequency RF it could actually begin to heat up exposed tissue. It is from this fear that institutions like the Marion Institute make suggestions about the link between cancer and where the cell phone is kept on the body. It is important to note that there is no significant evidence that suggests cell phones are capable of physically increasing the body's temperature. However, since we live in a world that has shown substantial progress in terms of mobile technology what if a cell phone that was capable of increasing temperatures was created?

     So can heat actually lead to an increased level of DNA damage? The answer is yes. Heating has been used to treat tumors by introducing genomic instability (one of the hallmarks of cancer). One paper caught my attention because it showed a connection between heat and gene amplification in cancerous cells. If cell phones are to blame for increased rates of DNA damage, heat should cause some form of measurable damage.  Yan et. al.'s measured DNA double strand breaks in response to elevated temperatures.
Here the top row shows cells stained with DAPI (blue) to shown DNA, and the row below is stained for γH2AX (green) which stains for a histone variant that is phosphorylated in the event of double strand DNA breaks. This histone 2AX is crucial in recruiting the machinery necessary to repair the damage. We can conclude that from the presence of phosphorylated H2AX, that the DNA of the cells exposed to higher temperatures (42ºC for 30 minutes) were significantly damaged.  This data clearly suggests that if cellular devices were capable of increasing the temperature of exposed tissues, there is evidence that we could begin to see an accumulation of double strand breaks and mutations in people who are constantly in contact with cellular devices.
Source: Yan Et. Al 

Concluding Thoughts

In conclusion, the RF radiation given off by cell phones is not high enough to heat up the body's cells enough to induce double strand breaks, nor are they a high enough energy to directly damage (ACS), but the argument that cellphones act as a source of carcinogens terrifies most people.  We live in an age where you cannot walk five feet without seeing a person who has or is using a cell phone. Most of the institutions that make this connection between cancer and cell phones use phrases like "your child is at risk", and for the most part it works in scaring people into believe that it is true. However, clearly we have not banned cell phones nor has there been sufficient evidence to convince some of our major health service companies that it is true. Currently, cell phones manufacturers are required to test and report the specific absorption rate (SAR) of their products. The Federal Communications Commission requires this to be well below what is considered to be harmful to health. The SAR testing procedure is an in depth assessment of RF radiation that can affect the body; they include tissue type and likely distance between the device and the body in order to estimate the associated risk.  One of the major reasons that the WHO still lists cell phones on the potential carcinogen list is that the habits and technologies connected to cell phone use have changed drastically in the last twenty years, and we must monitor people to ensure that our hypotheses of cell phone safety are valid.


  1. "Cellular Phones." Cellular Phones. American Cancer Society, Apr. 2012. Web. 05 May 2014.
  2. Clancy, S. (2008) DNA damage & repair: mechanisms for maintaining DNA integrity. Nature Education 1(1):103
  3. "Electromagnetic Fields and Public Health: Mobile Phones." WHO. World Health Organization, n.d. Web. 05 May 2014.
  4. Lewin, Benjamin, Jocelyn E. Krebs, Stephen T. Kilpatrick, Elliott S. Goldstein, and Benjamin Lewin. Lewin's Genes X. Sudbury, MA: Jones and Bartlett, 2011. Print.
  5. Specific Absorption Rate (SAR) For Cell Phones: What It Means For You. Federal Communications Commission, n.d. Web. 03 May 2014.
  6. Yan, Bin, Ruoyun Ouyang, Chenghui Huang, Franklin Liu, Daniel Neill, Chuanyuan Li, and Mark Dewhirst. "Heat Induces Gene Amplification in Cancer Cells." Biochemical and Biophysical Research Communications 427.3 (2012): 473-77. Print.