Effect of Mobile Phone Emissivity on Bacterial Cell Cultures

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Abstract

The objective is to study the effects of cell phone radiation on Escherichia coli and Staphylococcus aureus. All cellular phone networks worldwide utilize a portion of the radio frequency spectrum designated as Ultra High Frequency, or "UHF", for the transmission and reception of their signals. The UHF band is also shared with Television, Wi-Fi and Bluetooth transmission. The cellular frequencies are the sets of frequency ranges within the UHF band that have been allocated for cellular phone use.

Due to historical reasons, radio frequencies used for cellular networks differ in the Americas, Europe, and Asia. The first commercial standard for mobile connection in the United States was AMPS, which was in the 800 MHz frequency band. In Europe, the first wide-spread automatic mobile network was based on the NMT-450 standard, which was in the 450 MHz band. As mobile phones became more popular and affordable, mobile providers encountered a problem because they couldn't provide service to the increasing number of customers. They had to develop their existing networks and eventually introduce new standards, often based on other frequencies. The GSM standard, which appeared in Europe to replace NMT-450 and other standards, initially used the 900 MHz band. As demand grew, carriers acquired licenses in the 1800 MHz band.

Cell Phone Radiation and Health

Mobile phone radiation and health concerns have been raised, especially following the enormous increase in the use of wireless mobile telephony throughout the world (as of August 2005, there were more than 2 billion users worldwide). This is because mobile phones use electromagnetic radiation in the microwave range. These concerns have induced a large body of research (both epidemiological and experimental, in non-human animals as well as in humans). Concerns about effects on health have also been raised regarding other digital wireless systems, such as data communication networks. The World Health Organization has concluded, based upon the consensus view of the scientific and medical communities, that serious health effects (e.g. cancer) are very unlikely to be caused by cellular phones or their base stations, and expects to make recommendations about mobile phones in 2007–08.

However, some national radiation advisory authorities, including those of Austria, France Germany, and Sweden recommend to their citizens measures to minimize exposure. Examples of the recommendations are:

* Use hands-free to decrease the radiation to the head.

* Keep the mobile phone away from the body.

* Do not telephone in a car without an external antenna.

However, the use of "hands-free" was not recommended by the British Consumers' Association in a statement in November 2000.

The rate at which radiation is absorbed by the human body is measured by the Specific Absorption Rate (SAR), and its maximum levels for modern handsets have been set by governmental regulating agencies in many countries. In the USA, the FCC has set a SAR limit of 1.6 W/kg, averaged over a volume of 1 gram of tissue, for the head. In Europe, the limit is 2 W/kg, averaged over a volume of 10 grams of tissue. SAR values are heavily dependent on the size of the averaging volume. Without information about the averaging volume used comparisons between different measurements cannot be made. Thus, the European 10-gram ratings should be compared among themselves, and the American 1-gram ratings should only be compared among themselves. SAR data for specific mobile phones, along with other useful information, can be found directly on manufacturers' websites, as well as on third party web sites.

Thermal Effects

One well-understood effect of microwave radiation is dielectric heating, in which any dielectric material (such as living tissue) is heated by rotations of polar molecules induced by10 the electromagnetic field. In the case of a person using a cell phone, most of the heating effect will occur at the surface of the head, causing its temperature to increase by a fraction of a degree. In this case, the level of temperature increase is an order of magnitude less than that obtained during the exposure of the head to direct sunlight. The brain's blood circulation is capable of disposing of excess heat by increasing local blood flow. However, the cornea of the eye does not have this temperature regulation mechanism. Premature cataracts have not been linked with cell phone use, possibly because of the lower power output of mobile phones.

Health Hazards of Base Stations

Another area of worry about effects on the population's health have been the radiation emitted by base stations (the antennas on the surface which communicate with the phones), because, in contrast to mobile handsets, it is emitted continuously and is more powerful at close quarters. On the other hand due to the attenuation of power with the square of distance, field intensities drop rapidly with distance away from the base of the antenna. Base station emissions must comply with ICNIRP guidelines of a maximum power density of 4.5 W/m² for 900 MHz and 9 W/m² for 1800 MHz. These guidelines are set for short term heating, which is the only understood mechanism of electromagnetic fields on biological tissue.

The ICNIRP guidelines are distrusted by some scientists, such as the BioInitiative group, who report that the existing standards for public safety are inadequate to protect public health. A 2002 survey study by Santini et al. in France found a variety of self-reported symptoms for people who reported that they were living within 300 meters (984 ft) of GSM cell towers in rural areas, or within 100 m (328 ft) of base stations in urban areas. Fatigue, headache, sleep disruption and loss of memory were among the symptoms reported. Similar results have been obtained with GSM cell towers in Spain, Egypt, Poland and Austria.

It is, however, important to note that these surveys do not show statistically significant clustering or causality and those complaining of adverse symptoms may be displaying the nocebo effect, unless this is controlled in the study. However, a study conducted at the University of Essex concluded that mobile phone masts were unlikely to be causing these short term effects in a group of volunteers who complained of such symptoms. The study has been criticized as being skewed due to drop-outs of test subjects, although electrical sensitivity lobby groups have praised the study as a whole, and these criticisms were answered by the authors.

Effects of Mobile Phone Radiation on DNA

This work depicts the effect of both intermittent and continuous radiation (1800 MHz) on ultured human diploid fibroblasts and cultured rat granulose cells. The author confirms the radiation caused DNA breakage by mean of both alkaline and neutral comet assay. For invalidating the explanation by thermal effects, both intermittent and continuous exposure methods were used. The results showed a stronger effect by the intermittent exposure which ascertained that DNA breakage cannot be attributed to the thermal effects of the radiation used.

Experiment Setup

The mobile phone which was used for the experiment was primarily based on a 900 MHz band. The source of radiation was short range wavelength used by the phone to connect to a base station. The uplink and downlink frequencies themselves served as variables as they are distinguishable frequencies. The experiment was meant to simulate a real life conversation on a cell phone and the effects of it on a biological system. As bacteria represent one of the simplest biological systems, they were the immediate choice for the research. The distance between the culture and the source served as a major parameter which was varied from 5 to 30 cm. The time of exposure was also correspondingly varied from 2 to 8 hrs. The major confirmatory tests for both the test organisms served as a powerful tool for gauging the effects of mobile phone radiation, if any, on bacterial cell cultures.

Conclusion

Most of the tests performed yielded negative results. The negative results signify that there is no substantial biological effect due to the radiation. Tests which yielded negative results were repeated again under standardized conditions without any significant change in the results. Standardization of the protocol was reviewed at each and every stage during the course of the research. The aberration in the Citrate usability test might point to a mutation in the plasmid conferring citrate usability in Escherichia coli. This might also be attributed to an error in the working of the key enzyme in citrate utilization which is citrate permease. This alteration cannot be wholly attributed to the mobile phone radiation as long exposure times cause significant increase in the temperature surrounding the test organisms. Citrate usability is a property proved to be conferred by plasmids in the bacteria. From previous research it is evident that the rise in temperatures put the bacterial system under stress which may lead to aberrations in the test results.

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