Cellular Phone Towers

Moh. M. Abu Safya School of medicine

An-najah N University23th.Mar.2011

Supervisor: Dr.samar musmar1

Introduction

• These towers, also called base stations, consist of :1. Electronic equipment. 2. Antennas that “receive and transmit radiofrequency (RF) signals”.

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Radiation

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Radiation

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• Def. : energy which comes from a source and passes through some material or space .

• 1. Non-ionizing radiation : “does not have sufficient energy to create ion pairs that damage the DNA of living organisms”

• e.g. : radio waves and microwaves .

• 2. Ionizing radiation “has sufficient energy”• e.g. : X-rays, gamma rays, neutrons, protons, alpha particles,

and beta particles .

Radiation Measurement

System Internationale (SI)

becquerel (Bq)

gray (Gy) sievert (Sv)

conventional system

curie (Ci) rad rem

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Radiation Measurement cont.

• Measuring Radiation Dose

• absorbed dose

• One Gy is equal to 100 rad.

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Radiation Measurement cont.

• Measuring Biological Risk

• Quality Factor

• rem = rad X Q .

• One Sv is equal to 100 rem 7

Radiation Measurement cont.

Common Radiation Exposures

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What dose of radiation if fatal?

The lethal dose of radiation varies.

1. LD 50 dose << is about 500 to 600 rems .2. 100% << is about 1000 rems .

Note : whole body and to be absorbed in a short time.

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How much radiation do I receive?

*The average value for background radiation on Earth is around 0.36 rems per year.

*The dose does depend on : 1. where you live . 2. how much time you spend on an airplane. 3. your number of medical x-rays. And so on ..

*The Nuclear Regulatory Commission imposes an annual limit for radiation dose of 5 rems.

*5.36 rems 10

What is RF energy and how can it affect the body?

• 1-electromagnetic radiation.• 2- non-ionizing radiation.• 3- Travel at a speed of light. • 4- Radio frequency (RF) is a rate of

oscillation in the range of about 30kHz to 300 GHz.

• 5. in mobile radio communication, radar , and broadcasting.

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Cell phone towers (Facts)

• radiofrequency (RF) waves.

• parallel to the ground.

• lower levels than those from radio and television broadcast stations

• Energy (disprop.) distance .

• height from 50-200 feet.

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How do cellular phone towers work?

• 1- When a person makes a cell phone call, a signal is sent from the phone's antenna to the nearest base station antenna.

• 2- The voice signals are then sent to a switching center, which transfers the call to its destination.

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How are people exposed to the energy from cellular phone towers?

• Signals are transmitted back and forth to the base station.

• Public exposure to radio waves from cell phone tower antennas is slight for several reasons : 1. The power levels are relatively low.

2. The antennas are mounted at high above ground level.

3. The signals are transmitted intermittently, rather than constantly.

At ground level near typical cellular base stations, the amount of RF energy is thousands of times less than the limits for safe exposure set by the Federal Communication Commission (FCC) .

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Do cellular phone towers cause cancer?

• cell phone tower might increase the risk of cancer.• agree/disagree

• 3-issues :• 1. The energy level of radiofrequency (RF) waves.• 2. The wavelength of radiofrequency (RF) waves.• 3. The level of RF waves present at ground level.

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Do cellular phone towers cause cancer? Cont.

• First issue :• The energy level of radiofrequency (RF) waves.

• 1. Is relatively low, especially when compared with the types of radiation that are known to increase cancer risk, such as gamma rays, x-rays, and ultraviolet (UV) light.

• 2. The energy of RF waves given off by cell phone towers is not enough to break chemical bonds in DNA molecules.

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Do cellular phone towers cause cancer? Cont.

• Second issue :• The wavelength of radiofrequency (RF) waves.

• RF waves have long wavelengths, which can only be concentrated to about an inch or two in size.

• SO , RF waves could not be concentrated enough to affect individual cells in the body.

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Do cellular phone towers cause cancer? Cont.

• Third issue :• The level of RF waves present at ground level.

• Even if RF waves were somehow able to affect cells in the body at higher doses, the level of RF waves present at ground level is very low -- well below the recommended limits .

• In fact, due to their lower frequency, at similar RF exposure levels, the body absorbs up to five times more of the signal from FM radio and television than from base stations.

• 50 years .

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Do cellular phone towers cause any other health problems?

• While high levels of RF waves can cause a warming of body tissues .

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Studies in people

• British researchers compared a group of more than 1,000 families of young children with cancer against a similar group of families of children without cancer.

• No link between : mother's exposure to the towers during pregnancy and early childhood cancer .

• IN FACT : About 30 studies have looked at possible links between cell phone use and tumors in people .

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Studies done in the lab

• Most of studies have supported the idea that the RF waves given off by cell phones and towers don't have enough energy to damage DNA directly.

• IN FACT : Some scientists have reported that the RF waves may produce other effects in human cells (in lab dishes) that might possibly help tumors grow

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What expert agencies say ?

• 1. International Agency for Research on Cancer (IARC).

• 2. National Toxicology Program (NTP).• 3. the US Environmental Protection Agency

(EPA) .

• have not classified cell phone towers as to their cancer-causing potential.

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What expert agencies say ?cont.

• According to WHO :• There is no convincing scientific evidence that the weak RF

signals from base stations and wireless networks cause adverse health effects.

• According to FCC :• Exposure levels on the ground that are typically thousands of

times below safety limits.

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Protection standards

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• 1. International Commission on Non-Ionizing Radiation Protection (ICNIRP) .

• 2. Institute of Electrical and Electronic Engineers (IEEE)

• National authorities should restrict access to areas where exposure limits may be exceeded .

Key text and links

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• 1. (ICNIRP) .• 2. (IEEE) .• 3. WHO .• 4. FCC .• 5. Nuclear Regulatory Commission .• 6. http://www.bt.cdc.gov/radiation .• 7. CDC .• 8. http:// www.cancer.gov• 9. (IARC).• 10. (NTP).• 11. (EPA)

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