A Comparative Study on the Electromagnetic Radiation Output from Cell Phones By Jacie Sellers Latta Jr. High School Abstract The purpose of this project was to determine whether radiation levels vary greatly between different models of cell phones, operations, or strength of signal. The null hypothesis was that the amount of electromagnetic radiation would not vary greatly between different models of cell phones, operations, or strength of signals. There were four phones that were tested: a Samsung Flight, a Pantech Matrix, a Apple Iphone, and a Blackberry Pearl. They were tested at three different distances, doing six different functions, and in a weak and strong reception signal areas. They were tested using an Extech Instruments EMF sensor on three different days to determine the amount of electromagnetic radiation that was emitted. The greatest amount of radiation was emitted when there were incoming calls. In areas of weak signal service there was a larger amount of radiation than in strong signal areas. The average quantity of radiation detected was greater the closer the cell phones were to the EMF sensor. The Blackberry Pearl emitted more than twice the amount of radiation at 3.98 mg than the Samsung Flight at 1.88 mg and almost four times the amount from the Pantech Matrix measuring 1.08 mg. The Apple Iphone emitted about 90% less radiation 0.39 mg than the Blackberry Pearl. Introduction Cell phones have become a large part of our society in the past decade. Approximately 270 million Americans and 4 billion people around the world use cell phones. (1) Almost every teenager and adult has one and also uses it daily. With the growing industry, the question over long term excessive low dose radiation linking to cell phones grows as well. The first official cell phone was used in Sweden by police in 1946. The phone was only able to make 6 phone calls before its battery was exhausted. That technology was distinctive of a two- way 1
radio. The technology used by our modern cell phones started with the making of hexagonal cells for mobile phones by D.H. Ring from Bell Labs in 1947. In 1982, AT&T received approval from the FCC for cellular services. Predominantly these phones were used in cars. The phones were heavy and required a large battery supply. In 1983, Motorola came out with the first truly transportable cell phone called the Motorola DynaTAC 8000X. This took 15 years to make and cost over 100 million dollars. This was the beginning of the first generation cell phones. In the early 1990 s the new cell phones were considered as second generation and were proficient enough to work on mobile phone systems. Second Generation phones used digital circuit switched transmissions. Most second generation phones ranged from 100 grams to 200 grams and were hand held devices without the need of a large battery. The third generation is available today and is much different than the 2G due to the many innovations in technology during recent years. Third generation phones receive text messages, and most offer email and internet services. (2) Fourth generation phones are the newest development on the market they are able to support data and voice exchange simultaneously and are much faster. Cell phone carriers are finding the transition to the 4G environment difficult. (3) Cell phones emit electromagnetic radiation because they use radio frequency waves to make and receive calls. All radio waves that encode signals emit electromagnetic radiation. This radiation in cell phones is generated in the transmitter and emitted through the antenna. (4) When a phone is on it is constantly sending and receiving RF signals to and from the nearest cell tower to maintain service.(5) When talking on a cell phone, most people place the phone next to their head. This puts the user in close proximity to the emitted radiation and some will likely be absorbed by the user. Some 600 studies have been conducted on the link between radiation and cell phone use, but the results have been conflicting. Henry Lai from Bioelectromagnetics Research Laboratory, Department of Bioengineering, in 1998, stated that it is difficult to deny that RF at low intensity can affect the 2
nervous system. (6) However, according to a new study funded by the European Union, researchers said in 2004 that radio waves from mobile phones harm body cells and damage DNA in laboratory conditions. (7) Several organizations, including World Health Organization and National Cancer Institute, say there is no conclusive evidence while some independent investigations, however indicate a link between health problems and cell phone use. (8) The results are also conflicting about the difference in radiation levels due to cell phone use. Many studies state it is best to hold the phone farther away from the user s head, stay in stronger signal range, and also warn t users to talk for short periods of time. The purpose of this project was to determine whether radiation levels will vary greatly between different models of cell phones, operations, or strength of signal. The null hypothesis is that the amount of electromagnetic radiation will not vary greatly between different models of cell phones, operations, or strength of signal. Methodology Materials: 4 Cell Phones (a Samsung Flight, a Pantech Matrix, a Apple Iphone, and a Blackberry Pearl) Extech Instruments EMF Sensor Ruler Notebook Procedure: To test the influence of signal strength, a location was selected where a weak signal (1-3 bars) was present. The EMF sensor was turned on and placed on a flat surface. While the phone was on, but inactive, the amount of electromagnetic radiation (mg measurements) emitted from each cell phone was measured and recorded while 0 cm away from the EMF sensor. This was 3
repeated with the cell phone 2.5 cm and 5 cm away from EMF sensor. This same process was repeated in a location where a strong signal was received (4-5 bars). To test the impact of type of cell phone activity on emitted radiation the same procedure was repeated while the cell phone was: 1. making an outgoing call (before connecting), 2. receiving a call (before connecting), 3. sending a text message, 4. receiving a text message, and 5. talking (after connecting). Results There were four phones tested on three days. They were tested during 6 different activities. The amount of electromagnetic radiation emitted by the phones varied greatly in range during all functions and signal strength. The activities measurements varied slightly with all phone models and signal strength. While inactive, the average amount of radiation was 9.63 mg. During outgoing calls, the average was 6.62 mg; however, during incoming calls the amount rose to 11.44 mg. The average for an outgoing text was 7.11 mg and for an incoming text there was an average of 4.78 mg. The average amount while talking (after connecting) was 7.25 mg. There was a large difference between the amounts of radiation emitted between the distances. The average amount of radiation emitted from all cell phones and all functions at 0 cm was 3.81 mg. The average at 2.5 cm dropped to 1.2 mg and to 0.49 mg at 5 cm. The amount of radiation emitted rose slightly in the weak signal strength areas compared to strong signal strength areas. The average amount reached 1.88 mg while the average from the strong signal strength was 1.79 mg. 4
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Analysis and Conclusion It was hypothesized that the amount of radiation would not vary greatly between the different type of phone operations, strength of reception signals, or device styles or brands of cell phones. After examining the data, it was concluded that the hypothesis was not supported as there was a distinctive difference between the factors affecting the radiation output from cell phones. The results showed that when receiving incoming calls the emitted radiation was18.8% higher while talking than when inactive. The amount of radiation dropped 36.6% from receiving calls to talking. Additionally, it dropped 34.1% while talking to receiving a text message. When testing strong versus weak signals the amount of radiation was 4.47% less for the strong signal than the weak. The weak signal strength was measured in an area where the cell phones had a reading of 1-3 bars of signal strength. The strong signal strength was measured in an area where the cell phones had a reading of 4-5 bars of signal strength. The distance between the phone and the EMF detector made a distinguishing difference. Radiation was measured from three different distances: 0cm away, 2.5cm away, and 5cm away. The radiation dropped 68.5 % from 0cm away to 2.5cm away, and then declined another 87.1% to the 5cm away. There were 4 phones that were tested and they varied significantly in the amount of radiation emitted. The Blackberry Pearl (3.98mgauss) emitted more than twice the amount of radiation than the Samsung Flight (1.88mgauss) and almost four times the amount from the 6
Pantech Matrix(1.08mgauss). The Apple Iphone (.39 mgauss) emitted about 90% less radiation than the BlackberryPearl. To improve this project it would be good to include additional phone styles or types added to the experiment. It could also be further expanded by testing the harm that could be caused to model organisms by being exposed to the amount of radiation emitted from the cell phones. It would have been better to add several more popular phone styles. From this project, I have learned that cell phones do emit more radiation than I expected even while they are inactive. Also it was interesting to discover the unique differences between the radiation emitted by function, signal strength, and cell phone type. This experiment has provided further insight and will help to increase the amount of information known concerning radiation and its link to cell phones. Cell phones users need to be informed about the measure of radiation that their phones will emit and told what the differences are in the extent of the radiation emitted between phone types or functions. Acknowledgements I would like to thank my parents for supporting and guiding me during all the long weeks of experimenting, writing, and preparing. I also would like to thank Mrs. Edens for helping me and guiding me through all the difficulties and putting in so the time to help her students be the best they can. 7
References 1. Walsh, Bryan, How Safe is Your Cell Phone. TIME Magazine. (2010) 2. History of Cell Phones. Retrieved from the World Wide Web at: http://www.tech faq.com/history-of-cell-phones.html, January 14, 2011, 11:42 am 3. 4G Cell Phone Networks: Where Do We Stand? Retrieved from the World Wide Web at http://www.techreveiwsource.com/miscellaneous/4g-cell-phone-networks-where-do-westand, January 14,2011, 11:47 am 4. 2001. How Cell-Phone Radiation Works. Retrieved from the World Wide Web at: http://electronics.howstuff.works.com/cell-phone-radiation.htm January 6,2011 11:23 am 5. Gersdorff, Sascha De, Cell Phone Radiation. Women s Health (2010) 6. Lai, H. 1998.Neurological Effects of Radiofrequency Electromagnetic Radiation. Retrieved from the World Wide Web at: http://www.mapcruzin.com/radiofrequency/henry_lai2.htm, January 26, 4:01 pm 7. Dangers of the Wireless Age. Retrieved from the World Wide Web at http://tuberose.com/cell_phones.html, January 26 4:07 8. Are Cell Phones Safe? Researchers Still Uncertain. Retrieved from the World Wide Web at: http://news.cnet.com/8301-30686_3-10351577-266.html January 7,2010 7:43pm 8