Remember Jon Krakauer's account of tragedy on Mt. Everest? We have an irrational perception of acceptable risk. For sheer enjoyment, we frequently are willing to expose ourselves knowingly to the possibility of severe injury. Just three weeks ago about a dozen climbers succombed to an ice fall on K2. In any good summer, roughly 100 people perish in mountaineering accidents in the Swiss Alps alone. V. Lischke and others report 462 fatalities for 1997 Europe-wide. According to the U.S. Dept. of Transportation, 4,810 Americans perished on motor bikes in 2005, translating into 73 riders per 100,000 bike registrations. The fatalities continue to rise. Last year 5,154 Americans died on their bike.
By contrast, according to wrongdiagnosis.com every year fewer than 50 in 100,000 Americans battle glioblastoma multiforme, that is the most aggressive and fatal type of brain cancer. Recent research studies link brain cancer with electromagnetic radiation from cell phones. A discussion of some studies can be found here. The debate has become ever more intense since Senator Edward Kennedy was diagnosed with malignant glioma, probably a glioblastoma multiforme. I discussed this type of brain cancer in my post dated June 3, 2008.
Prudence is advised in the debate on a possible association between cell phone-related electromagnetic radiation and brain cancer. The energy of electromagnetic waves is directly proportional to their frequency. The spectrum of the frequencies ranges from meter-long radio waves via the nanometer-long waves of visible light to atom-sized gamma rays. The shorter the wave length, the higher the frequency and the greater the energy that potentially can harm our genes. DNA may be altered directly through the absorption of radiation energy or indirectly through radiation-produced free radicals that may react chemically with the DNA. Even low amounts of energy can damage DNA and may theoretically result in uncontrolled cancerous cell proliferation. However, our cells are provided with DNA repair mechanisms. Commonly many hits are needed to overcome the defenses and cause noticeable damage. Alas, the defenses appear to wear out with advancing age and we may become more susceptible to cancer.
To determine thresholds for harm from electromagnetic radiation, epidemiological studies are conducted that compare the health records of people with known exposure to those of people who match this group in all aspects, except the exposure. Professionals with job-related extraordinarily high exposure are frequently enrolled in the group of the potentially affected to improve the chances of discovery. Hardell and others (2005) observed that Swedish long-term users of analogue mobile (NMT) phones like the now obsolete car phones developed a significantly higher risk for auditory nerve tumors (acoustic neuromas) on the side of phone use. Digital mobile (GSM) phones like our modern cell and cordless phones did not increase this risk consistent with findings in Denmark (Christensen and others, 2004). The prevalence of acoustic neuroma in the U.S. is low. Less than 1 in 1000 Americans is affected. According to ctia.org, roughly 264 million wireless subscriptions are active at present.
Though the results of such studies provide important leads on the type of the potential harm to our health and may be instrumental for safety considerations at the work place, they cannot be easily extrapolated to regular phone users. The amount of radiation energy deposited in the auditory nerve can only be estimated. Moreover, the effects cannot be ascertained with the data collected at higher doses because of the non-linearity of the relationship between dose and effect and the increasing scatter of the observations at progressively lower doses. The concerned may opt to use plug-in extensions for ear and mouth pieces or voice-activation as precaution.
- National Public Radio's All Things Considered ran an interesting update on this issue today. You may wish to read the report and listen to the podcast by Allison Aubrey entitled "Doctors Urge Research On Cell Phone-Cancer Issue" (09/25/08).
- On Aug. 24, an ice fall swept away a party of twelve on the Mont Blanc du Tacul, a smaller brother of the White Lady. Eight are missing. I once stood on this mountain at a different time in the year. I was fortunate to have a friend as guide who understood risk well (10/21/08).
- Maggie Fox reports in her post with the title "U.S. senator promises look into cellphone-cancer link" published online on Reuters today that Senator Tom Harkin, chairman of the Committee for Health, Education, Labor and Pensions, plans to encourage more research to examine whether the use of cellphones may cause cancer. The fear persists (09/14/09)!
- The environmental working group lists the head-absorbed power [W/kg] of the radio waves emitted from a number of cell phones in this table (06/16/2010).
- Volkow and others (2011) report in this week's issue of the Journal of the American Medical Association that cell phone radiation is statistically significantly associated with an acute increase of glucose metabolism in the temporal and frontal lobes of the cerebral cortex by, on average, 7.2 percent on the side the active, but muted, phone was held for 50 minutes. The researchers used the [18F]fluorodeoxyglucose method and positron emission tomography (PET) to determine regional cerebral glucose utilization rates in 47 healthy volunteers. They conclude in the abstract of their communication that “this finding is of unknown clinical significance.” Indeed, the finding does not provide any insight into the cellular mechanisms underlying the observed increase. Under healthy physiological conditions, brain glucose metabolism does not rise to levels posing a health hazard. I have written on this topic in my post with the title "Good News for Brain Energy Use" published Sep. 12, 2009. If the sole aim of this study had been to investigate the potential influence of modern-day cell phone radiation on brain energy metabolism, the study could have been conducted with mice at lower cost, sparing the participants unnecessary exposure to ionizing radiation from PET (02/24/11).
- Epidemiologists have recently come to discrepant conclusions on the risk of cancer associated with cell phone use. According to Scott Hensley's report with the title "Cellphone Use May Be A Cancer Risk After All" on National Public Radio's All Things Considered today, a recent World Health Organization review conducted by 31 experts from 14 countries found sufficient evidence that may support a correlation between cellphone use and gliomas and acoustic neuromas. The study will be published in the July issue of the journal The Lancet Oncology. By contrast, a comprehensive case–control study with 2708 glioma and 2409 meningioma cases and matched controls from 13 countries published last year by The INTERPHONE Study Group (2010) could not establish any elevated risks with mobile phone use with certainty (05/31/10).
- Christensen HC, Schüz J, Kosteljanetz M, Poulsen HS, Thomsen J, Johansen C (2004) Cellular telephone use and risk of acoustic neuroma. Am J Epidemiol 159: 277-283.
- Hardell L, Carlberg M, Hansson Mild K (2005) Case-control study on cellular and cordless telephones and the risk for acoustic neuroma or meningioma in patients diagnosed 2000–2003. Neuroepidemiology 25: 120-128.
- The INTERPHONE Study Group (2010) Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case–control study. Int J Epidemiol 39: 675-694.
- Volkow ND, Tomasi D, Gene-Jack Wang G-J, Vaska P, Fowler JS, Telang F, Alexoff D, Logan J, Wong C (2011) Effects of cell phone radiofrequency signal exposure on brain glucose metabolism. JAMA 305: 808-813.