Baseball legend Yogi Berra is said to have fretted, “I don’t want to make the wrong mistake.” As opposed to the right mistake? A mistake that is both wrong and right is the alleged connection between cell phone use and brain cancers. Reports of a link between the two have periodically surfaced ever since cell phones became common appendages to people’s heads in the 1990s. As recently as this past May 17, Time magazine reported that despite numerous studies finding no connection between cell phones and cancer, “a growing band of scientists are skeptical, suggesting that the evidence that does exist is enough to raise a warning for consumers—before mass harm is done.”

Their suggestion follows the pre­­­cautionary principle, which holds that if something has any potential for great harm to a large number of people, then even in the absence of evidence of harm, the burden of proof is on the unworried to demonstrate that the danger is not real. The precautionary principle is a weak argument for two reasons: (1) it is difficult to prove a neg­a­tive—­that there is no effect; (2) it raises unnecessary public alarm and personal anxi­­ety. Cell phones and cancer is a case study in the pre­cautionary principle misapplied, because not only is there no epidemiological evidence of a causal connection, but physics shows that it is virtually impossible for cell phones to cause cancer.

The latest negative findings men­­tioned by Time come out of a $24-mil­­lion research project published in the International Journal of Epidemiology (“Brain Tumour Risk in Relation to Mobile Telephone Use”). It encompassed more than 12,000 long-term regular cell phone users from 13 countries, about half of whom were brain cancer patients, which let researchers compare the two groups. The authors concluded: “Overall, no increase in risk of glioma or meningioma [the two most common types of brain tumors] was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation.”

This application of the precautionary principle is the wrong mistake to make. Cell phones cannot cause cancer, because they do not emit enough energy to break the molecular bonds inside cells. Some forms of electromagnetic radiation, such as x-rays, gamma rays and ultraviolet (UV) radiation, are energetic enough to break the bonds in key molecules such as DNA and thereby generate mutations that lead to cancer. Electromagnetic radiation in the form of infrared light, microwaves, television and radio signals, and AC power is too weak to break those bonds, so we don’t worry about radios, televisions, microwave ovens and power outlets causing cancer.

Where do cell phones fall on this spectrum? According to phys­i­­cist Bernard Leikind in a technical article in Skeptic magazine (Vol. 15, No. 4), known carcinogens such as x-rays, gamma rays and UV rays have energies greater than 480 kilojoules per mole (kJ/mole), which is enough to break chemical bonds. Green-light photons hold 240 kJ/mole of energy, which is enough to bend (but not break) the rhodopsin molecules in our retinas that trigger our photosensitive rod cells to fire. A cell phone generates radiation of less than 0.001 kJ/mole. That is 480,000 times weaker than UV rays and 240,000 times weaker than green light!

Even making the cell phone ra­di­a­tion more intense just means that there are more photons of that energy, not stronger photons. Cell phone photons cannot add up to become UV photons or have their effect any more than microwave or radio-wave photons can. In fact, if the bonds holding the key mole­cules of life together could be broken at the energy levels of cell phones, there would be no life at all because the various natural sources of energy from the environment would prevent such bonds from ever forming in the first place.

Thus, although in principle it is difficult to prove a negative, in this case, one can say it is impossible for cell phones to hurt the brain—with the exception, of course, of hitting someone on the head with one. QED.