Longer, over 50-minute cell phone calls can increase brain activity in the place closest to the camera’s antenna, reports The Journal of the American Medical Association, published Wednesday.
Dr. Nora D. Volkow, dir. The National Institute on Drug Abuse in Maryland, which led the research, cautions that registered changes are minor. Brain activity near the camera’s antenna increased by only 7 percent. On this basis, therefore, it cannot be said that cell phone radiation is harmful, let alone that it can cause a brain tumor.
However, these are the first studies to show that weak radio radiation emitted by cell phones can directly affect nerve cells in the brain.
Researchers tested 47 people who had two cell phones pressed to both ears so that they did not know which device was receiving the signal. During the interview, their brain activity was measured by measuring glucose levels using a device called PET. The larger it is, the more active the work of nerve cells is, because glucose is the only source of energy for brain cells. Thanks to this, oncologists diagnose, inter alia, brain tumors, and neuroscientists study which areas of the brain are responsible for what.
Dr. Volkow says that greater brain activity near the antenna indicates that the brain is sensitive to electromagnetic radiation sent by cell phones. In her opinion, further research is needed to show what effects may have an intensive use of them over a long period, after 10, 15 or 20 years.
Prof. Henry C. Lai from the University of Washington says in a commentary in JAMA that so far, it has only been possible to show that prolonged cell phone calls may have less significant effects, eg contribute to sleep disorders. However, everyone is interested in whether they can contribute to the development of a brain tumor, which may show up after 20-30 years. And there is no full agreement on this.
The largest Intrephone study to date, published in 2010, has failed. It included people aged 30-59 in 13 countries, some of which developed a brain tumor. It is not clear from these studies that mobile phones are harmful. It suggests that they may even reduce the risk of a brain tumor.
Other studies look directly at the effects of electromagnetic radiation on living organisms. But their results are just as astonishing. One of such experiments was carried out by prof. Henry Lai. It showed that rats may experience memory impairment due to the influence of low-energy radiation. SAR indicator (Specific Absorption Rate), because only from 0,0006 to 0,06 W / kg. It is much lower than what is assumed to be safe.
The SAR indicator shows radiation with a frequency above 10 MHz, which, after entering the body, is converted into heat and may lead to an increase in body temperature (the frequency of radio radiation reaches 300 MHz). A device that emits radiation, the SAR of which does not exceed 4 W / kg, is assumed to be safe for humans. This means that under normal weather conditions it will heat the body of an average person by no more than about 30 deg. C after 1 minutes. This is believed to be safe.
For mobile phones, the SAR value, expressed in watts per unit body weight in kilograms, should not exceed 1,5-2 W / kg. At least such standards are in force in most countries.
The most pressing question is whether cell phone radiation is harmful to children. Their nervous system is more sensitive because it is just developing. In addition, for anatomical reasons, radio radiation can penetrate deeper into their heads than in adults. And children are using mobile phones more and more often and earlier. The American Kids research shows that 20% of them use them regularly in the United States. 6- and 7-year-olds.
Research that can prove anything on this topic is only just beginning. In April 2010, a project called Cosmos was launched in the United Kingdom, Sweden, Finland, the Netherlands and Denmark, which assumes that 30 people will be monitored for 250 years. people. aged from 18 to 69.
The international Mobi-Kids study was also launched this month. This time, the researchers want to check whether in people aged 10-24 who have developed a malignant brain tumor, the frequent use of cell phones could have some influence on their disease.
Regardless of the results of these studies, it is worth following a few basic recommendations in the use of mobile phones. Avoid holding the camera to your head when making calls to the number you have dialed. It is best to use the handset during the conversation. Pregnant women should avoid holding the phone in the belly area. In turn, children and adolescents should send SMS more often and talk less often.
Zbigniew Wojtasiński (PAP)