How safe are mobile phones?

Transcription

1 How safe are mobile phones? Q This unit is about why scientists disagree. Different people produce different results and sometimes different people interpret the same results in a different way. The recent scare about the safety of mobile phones is a good example. Before you start Do you use a mobile phone? Often Sometimes Hardly at all Never Do you think mobile phones are safe? Yes No Don t know Don t care questions Now do the activities After you have finished Explain why the experts do not agree on whether mobile phones are safe. Imagine a new piece of research is published: Scientists studied 10,000 people for a period of 10 years. They found that people who did not use mobile phones were just as likely to suffer a brain tumour as people who did. a. Would this new research settle the argument? b. Explain your answer. a. After studying this unit, how do you feel about the safety of your mobile phone? More worried Just the same Less worried b. Give a reason for your choice.

2 Mobiles in the news A 1 MOBILE PHONES COULD DAMAGE YOUR HEALTH Many people live or work near a mobile phone transmitter. It sends out microwaves to mobile phones in the local area. activities Read the newspaper article and answer the questions below: A GOVERNMENT DEMANDS REDUCTION IN RADIATION FROM MOBILE PHONES recent government report demands huge reductions in the amount of radiation that mobile phones are allowed to give out. It will also tighten up rules about where mobile phone transmitters can be installed. This is because of growing fears that the radiation, called microwaves, is a serious health risk. Last year, a mobile phone mast was put up just 7 metres from the home of Mrs. Wood. Shortly after, her husband was told by doctors that he had cancer. A tumour was growing in his brain. The couple are convinced that the ugly metal structure is to blame. Mrs Wood said Nobody can say it isn t down to the mast. As time went by, Mr and Mrs Wood and their two children found they were not sleeping as well as they used to. This effect of microwaves on sleep is already known from scientific research. Then Mrs Wood noticed that if she scratched or knocked herself, her skin was taking longer and longer to heal. Also, her short-term memory was often poor. Last night, Mrs Wood welcomed the news of the government report. And she is not alone. A committee of experts has heard evidence from lots of other ordinary people, who believe that masts and mobile phones are damaging their health. As more and more of us get connected, there could be a risk of many more people getting brain tumours. While it may be good to talk, it is not necessarily safe. Until more is known about the dangers, these new government rules are a vital protection. Name the type of radiation which mobile phones produce. What has happened to Mr Wood since the mobile phone mast was installed? Why does Mrs Wood believe that it was the mast which caused her husband s illness? a. List three other symptoms that Mrs. Wood and her family have which she blames on the mast. b. Does the article suggest that people other than Mrs Wood have suffered from the use of mobile phones? Give a reason for your answer. a. Do you think Mrs. Wood is right to blame the mobile phone mast? b. What extra evidence would you look for to help you decide? c. What do you think should be done about mobile phone masts in the meantime? Give reasons for your answer.

3 TV Debate A 2 Your local TV station has invited in some experts to discuss whether or not mobile phones are safe. You are to play the part of one of these experts. You will be given information about the expert s point of view. Before the debate, study your expert Evidence Card. Decide whether your expert thinks mobile phones are safe or not. Highlight important words or phrases on the card which provide evidence for this opinion. Start the debate. Each expert takes turns to give their point of view Tip: You can refer to your Expert Card when you speak, but don t read it out word for word. activities Give everyone a chance to ask each other questions. Always try to answer the questions with evidence, not just an opinion. At the end of the debate complete the table below: Points we agree about Point we disagree about

4 Experts and evidence A 2 In this activity you will find out what four different experts think about mobile phone safety. You will see that the experts do not agree about what the evidence means. Use the information on the Evidence Card to complete the table below. Expert Do they think mobile Two pieces of evidence phones are safe? the expert uses to support their opinion. Anthony Smith: Director of Marketing, Digiphone Corporation activities Professor D Gupta: Leader of Research Project looking into mobile phone safety David Carvel: Press Officer, Radiation Information Organisation Dr. Amelia Harrison: Author of the book Magic Light: The Uses and Dangers of Electromagnetic Radiation a. Which experts agree with Anthony Smith? Which ones disagree? b. Give two pieces of evidence for disagreeing with Professor Gupta. Imagine all the experts are discussing together whether mobile phones are safe. Do you think they will come to a decision in the end? Give a reason for your answer. Two experts quote the same piece of evidence: People who do not use mobile phones are just as likely to get brain cancer as mobile users. But mobile users are more likely to get one particular type of brain cancer. Copy and complete the sentences to show two interpretations of the evidence above: a. This evidence suggests mobiles are safe because b. This evidence suggests mobiles are dangerous because

5 Experts opinion Anthony Smith: Director of Marketing, Digiphone Corporation Scientists do not understand how microwaves could cause cancer. Some other types of radiation with higher energy can cause cancer. They do this by changing the DNA molecules in cells (see diagram). Microwave radiation has too little energy to do this. Gamma rays X-rays Ultra Higher energy radiation which changes DNA Visible Infra red Microwaves Radio and TV Lower energy radiation A 2 evidence cards Microwaves do heat up cells. This is how microwave ovens work. If you heat cells in the body enough you damage them. But microwaves from mobile phones are far too weak to do this. Mild exercise will heat up your brain cells more. Mobile phone masts do give out more microwaves than phones. But the amount of radiation you receive from a mast is very small. This is because the masts are much further away than your phone. The strength of radiation drops very quickly the further away you get. Professor D Gupta: Leader of Research Project looking into mobile phone safety Scientists in Sweden looked at 200 people with brain tumours. They found no evidence that using a mobile phone increased the chance of having a tumour. But, mobile phone users were over twice as likely to have a tumour near their phone ear than in other parts of the brain. Scientists in the US did similar research, using 450 people with brain tumours. Again they found no evidence that using a mobile phone increases the chance of having a tumour. But there were more than twice as many mobile phone users who had a particular type of tumour (called a neurocytoma) compared with people who did not use mobile phones. Increase in mobile phone use We must be careful. Firstly, the number of mobile phones is increasing at an incredible rate (see diagram). So even a tiny increase in the risk of brain cancer could cause many more deaths across the world. Secondly, brain tumours can take many years to develop. Mobile phones have not been around for very long. So it might be a long time before we find out whether mobile phones cause brain cancer or not. Number of mobile phones in use Year

6 Experts opinion A 2 David Carvel: Press Officer, Radiation Information Organisation Research from Sweden and the US finds no evidence that people who use mobile phones have a greater risk of brain cancer. The only evidence is that mobile users are more likely to get one particular type of brain cancer. They are actually less likely to get other types of brain cancer. Does this mean microwaves protect against the other types of cancer? There is a problem with the research into mobile phones and brain cancer. The scientists only looked at a few hundred people. This is not enough. The finding could be an accident. Just like when you toss a coin a few times you could end up with all heads. At the moment there is no strong evidence of any health risks with mobile phones. The World Health Organisation is carrying out a large European study looking at 3000 people with brain tumours. It will be several years until we know the results. evidence cards Dr Amelia Harrison: Author of the book Magic Light: The Uses and Dangers of Electromagnetic Radiation which looks at the history of radiation use We now know X rays can be dangerous. But one early use of X-rays was at fun fairs. People put their hands in a strong X ray beam so they could see the bones in their hands. 50 years ago people used X rays to check whether new shoes fitted child s feet properly. Was it a good use of radiation? X rays are used in medicine to photograph people s insides. But in the past, doctors sometimes used very high doses because they did not know the dangers. For example, they used strong X-rays to search for breast cancer. In the early days they may have caused more cancers than they found. Microwaves are another form of radiation and they may turn out to be as dangerous as X-rays. It looks unlikely on the basis of current evidence, but the lesson of history is that we should be very careful with new uses of radiation. We will be able to relax more when scientists have thoroughly investigated the possible effects on our bodies.

7 Proving a link E Scientists are more likely to believe in a link between microwaves and brain cancer if they understand how microwaves could cause this effect. The table summarises some recent research. Research Team Experiment Comments led by and findings David de Pomerai UK Henry Lai US The scientists exposed some tiny nematode worms to microwaves The worms grew 5% faster They exposed rats to microwaves They found changes to several brain chemicals which we know affect memory and alertness If microwaves can cause cells to divide more quickly, they could be affecting the DNA in the cell. Changing DNA can cause cancer Studies with humans have shown no effect on short-term memory Other scientists have not been able to repeat these findings Some human research suggests microwaves speed up reaction times extension John Tatersall UK Michael Repacholi Australia Gerald Hyland UK They looked at how microwaves affect different cells in slices of rat brain They found that microwaves weaken the response of cells in one part of the brain (called the hippocampus) The scientists exposed some mice to microwaves These mice were twice as likely to get a particular type of cancer (called a lymphoblastic lymphoma) The scientist has a theory that microwaves affect the waves that came from the brain itself The frequency of the radiation from mobile phones matches the frequency of brain waves The hippocampus is too deep inside the human brain for weak microwave radiation to reach it They used genetically engineered mice who were more likely to get this type of cancer anyway Other researchers have not been able to repeat the results. This theory has not yet been tested, so scientists have no evidence for it Look at the findings in the table. Give 3 different ways in which microwaves could affect the brain. For each one, say whether you think the evidence is strong or weak. a. Explain why the evidence for some of these findings is weak. b. What would you do to gather stronger evidence? Pick one of the following activities: a. The research teams need money to pursue their research. Imagine you have a grant to give to one of the teams. Who will you choose? Why? What experiment should they do next? Write a short paragraph giving your decision and the reasons for it. b. Your local radio station has invited you to comment on recent research into microwaves and brain cancer. You will be interviewed live and you have just 90 seconds to speak. Prepare the script for your talk.

8 How safe are mobile phones? T The unit starts by asking pupils for their opinions. They will almost certainly have no evidence to support their opinions at this stage. Mention that many scientists have to approach a problem in a similar way with limited or no evidence. But does the search, and collection of evidence, always make the situation clear? You will come back to this question after completing the unit. The first sheet helps to organise the pupils work during the unit and stresses that it is about evidence rather than just mobile phones. Suggestion for further activity Ask pupils to produce an article to go in a magazine for parents. Can microwaves damage your child s brain?. You could offer support by providing a layout with subheadings like the possible dangers health risk factor fiction, microwaves - what exactly are they? Evaluation: judge the value of what is read After you have finished Questions to reinforce the Ideas and Evidence learning objective, for class use or for homework found on the same sheet as Before you start The CD contains a glossary of terms used in this unit Reasoning: make judgements and decisions informed by evidence Extension: Proving a link More demanding questions for more able pupils. Language Different ways to interpret evidence Information-processing: Classify information Key skills/thinking skills Communication: contribute to a group discussion Activity 2b: Experts and evidence A series of structured questions, based around the expert Evidence Cards, This is a useful alternative to the TV debate. More about mobile phone safety For the latest news and articles visit the PRI website: See CD for references to GCSE syllabuses The activity can also be run as a whole class debate. The part of each expert can be shared by 2 4 students. Prior learning It will helpful if pupils know that waves carry energy scientific uncertainty - about whether a factor causes an outcome, particularly if it is difficult to explain how [I&E d) extension] It helps pupils to get into role if they form expert groups beforehand to talk through the evidence for a few minutes. For more information on group discussion and role plays, see CD (general teachers notes) The Expert Evidence Cards provided can be simplified by omitting the final point(s) from each card. Timing guidelines Mobiles in the news and TV debate require approx 60 mins classroom time plus a homework to prepare for the discussion Ideas and evidence there can be more than one explanation of the same findings, which leads to a scientific controversy [I&E b)] Activity 2a: TV Debate This activity has been successfully run in groups of five pupils: one for each expert and one to act as chair. Pupils put their point of view, and then discuss. They can report the conclusion of their discussion. All activities except Proving a link aim to be accessible for C/D ability pupils Routes through unit TV debate and Are mobile phones safe? are alternative approaches to cover the main learning objective Science content evaluate the dangers of exposure to electromagnetic radiation, using information provided Activity 1: Mobiles in the news Introduction, where pupils read the newspaper article and answer questions Where the unit fits in Electromagnetic radiation Learning objectives Activities Notes Pupils should learn: teacher s notes The Pupil Researcher Initiative (PRI) is sponsored by the Engineering and Physical Sciences Research Council (EPSRC), and the Particle Physics and Astronomy Research Council (PPARC).