Bachillerato

Evaluación

Instrucciones.

1. Guarda este archivo en tu computadora como: u1_ eva_ nombre de usuario.
2. Lee detenidamente el texto.
3. Contesta el cuestionario incluido.
4. Al terminar, envía el cuestionario a tu asesor a más tardar el domingo a las 20:00 hrs. para su registro.

TEXTO

En el texto se exponen una serie de opiniones y estudios que van en el sentido de que el uso de loscelulares es dañino, y otros, en el sentido de que es completamente inofensivo.



Introduction

Cell phones and cancer are in the news all the time now it seems. But almost everyone uses cell phones. All over the world, tens of millions of people are pressing them against their heads for hours every day. In the U.S. it is estimated that therewere at least 100 million cell phone users, as of early 2002, and that number has continued to climb.

So what's the fuss? Is cancer caused by cell phones a serious concern, or the media's every day’s manipulation?

A cell phone, and a cordless phone, uses a low level form of microwave radiation in order to send and receive their signals. Microwaves, as you know, are used to cook food. Asthe radiation penetrates tissue, it causes it to heat.

Is this a problem for us with cell phones? That is the current debate. Let's examine the positions and the known evidence, without prejudice.

Cell phones are dangerous:

* Microwaves are emitted by them.
* You hold the source of the emission against your brain.
* There are claims that people have had brain tumors inthe exact size, shape and position as the antenna on their cell phone.

Cell phones are safe:

* A very, very low level of Radio frequency (RF) energy is used in Cell phones -too low to cause damage.
* The type of energy emitted is non-ionizing -meaning it doesn't cause damage to chemical bonds or DNA.
* Cell phones and cordless phones have been used by hundreds of millions ofpeople for years.

Is there a problem? Let’s analyze some scientific data:

Latest News:

* January 2006: A four-year long British study was performed by the London-based Institute of Cancer Research and three British universities. It was found that talking on a cell phone had no effect on tumor rates. The researchers included 966 people with glioma brain tumors and 1,716 healthyrespondents. Individuals were questioned on first use, lifetime years of use, cumulative hours of use, and number of calls they made.

* March 21, 2005: Dr. Lai also agrees with recommendations to use a headset to minimize potential exposure.

Studies, Facts and Evidence

What is the radiation produced by a cell phone?

Like televisions, alarm systems, computers, and all other electricaldevices, cell phones (also called mobile phones) are radio devices that use radiofrequency (Rf) energy emit electromagnetic radiation. They operate at low power (less than 1 watt) by transmitting and receiving electromagnetic radiation in the radiofrequency (RF) end of the spectrum. Radiation, which is called "ionizing", can be absorbed by tissue and break molecules apart, such as gamma rays andx-rays, are known to cause cancer. The concern is that the cell phone and its antenna (the source of the radiation) are held close against the head). The damage to the DNA molecules is thought to be the cause.

Radiation in perspective

Power
Newer phones are digital. The older analog phones are expected to be eradicated from the market by 2006. The major difference is that analog phones usemuch more power than digital. Analog use about 1.3 Watts, while a digital mobile phone is designed to operate at a maximum power level of 0.6 watts. By comparison, a household microwave oven uses between 600 and 1,100 watts.

Frequency
In the United States, mobile phones operate in a frequency ranging from about 850 to 1900 megahertz (MHz). In that range, the radiation produced is in the...