In May, 2011, a group of 31 scientists from 14 countries examined the risk of cancer caused by cell phone radiation. In an almost unanimous decision, the IARC (International Agency for Research on Cancer) classified this type of radiation as a possible cancer risk. While the decision does not affect cell phone users directly, all mobile device owners should be familiar with the decision and the reasons for it. It may affect how you use your device.
The specific form of cancer considered by the IARC is glioma, a malignant form of brain cancer with about 150,000 new cases worldwide per year, the highest rates occurring in developed countries. The current rate in the U.S. is 6.7 per 100,000. While the rate has been increasing slowly over the last 20 years, the rate of increase is slowing down, and there is no correlation to increased cell phone use.
Working Group Findings
The IARC working group considered research and studies linking electromagnetic radiation at radio frequencies and cancer generally. It specifically looked at occupational exposure to radar and microwaves, environmental exposure to wireless transmissions and exposure from personal mobile devices. The May 31, 2011, press release from IARC gives the details of the work, the studies and the classification.
The group evaluated the evidence for a link between electromagnetic radiation and glioma as “limited.” It called the evidence for the other links it studied “inadequate.” A finding of “limited” evidence justifies a classification of cell phone radiation as “possibly carcinogenic to humans.”
Electromagnetic radiation is all around us and a lot of it passes through our bodies continuously without doing any damage. It can damage human tissue in three ways.
- The most powerful radiation, such as X-rays, can ionize molecules and cause changes in DNA and cell structure.
- Less powerful radiation, like microwaves used in cooking, can heat tissue and cause thermal damage.
- Cell phone radio waves are not powerful enough for ionization or heat, but do have an effect through the electromagnetic fields they generate. These are called non-thermal effects and the mechanisms are not well-understood.
The “limited” evidence found by the IARC working group dealt with non-thermal effects of cell phone radiation on brain tissue.
Cell Phone Radiation Classification
The IARC classifies cancer threats according to a system that evaluates their danger. The system divides threats into four groups. Group 1 is carcinogenic to humans. Group 2 may be carcinogenic. Group 3 is not carcinogenic and Group 4 is probably not carcinogenic. Group 2 has two sub-classifications. Group 2A is probably carcinogenic to humans and Group 2B is possibly carcinogenic. The working group classified cell phone radiation in Group 2B.
The IARC defines the “limited” evidence that led to the classification. It found studies showing an association between cell phone radiation and brain cancer that provided a credible mechanism for the radiation to cause the cancer. The evidence is considered “limited” because the working group could not rule out that the association was the result of bias, chance or misinterpretation. A finding of “inadequate” evidence means that the studies that the group found did not allow them to make a credible classification .
A review of the facts shows that the classification of the working group was and continues to be accurate. The only alternate classifications would have been to say cell phone radiation is not a carcinogen or that it probably is not one. Since the group found studies that made an association of electromagnetic radiation with glioma, these classifications are not appropriate, even if the studies lacked credibility.
The IARC has not changed the classification since 2011. This means that the IARC has not become aware of any studies allowing them to change the risk from possible to probable. They can’t change the risk to the non-carcinogenic Group 3 because a threat can only be non-carcinogenic if there is either no mechanism or no exposure. For cell phones there is exposure to radiation and the mechanism of electromagnetic fields exists. As a result, in the face of the studies it found, the IARC may eventually change the classification to Group 4, “probably not carcinogenic to humans,” if no further studies make such a link.
For cellphone users, there are several implications. In the absence of greatly increased rates of brain cancer over the past several years, the risk of brain cancer from cell phone use can’t be immediate or medium term. Since cell phones have been used by millions of people over more than 20 years, the cancer rates would show a rise.
There is a small possible long-term risk of glioma from lifelong cellphone use, but this possibility is based on an absence of data rather than a confirming study. The IARC findings and classification support this interpretation.
Cell phone users who want to address this risk can start using headsets, earphones or hands-free technology to avoid placing the cellphone close to their ears. Since the effects are cumulative, it is possible to reduce the risk by using the cellphone close to the head less frequently. The effect of radiation is very sensitive to distance. Holding the cell phone only slightly away from the ears can reduce the amount of radiation reaching the brain by up to 90 percent.
In the absence of a study confirming a closer and more credible association of cell phone radiation with glioma, the risk has to be seen as very small. The average cell phone user faces many greater risks in traffic and from other diseases.
Featured photo credit: Ed Yourdon