chapter 7 AS science in society - radiation

notes on chapter 7 radiation

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Chapter 7: radiation
The issues
Many people have negative attitudes towards the use of radiation and radioactive
substances, particularly in large scale applications such as nuclear power stations.
Much less opposition to the medical use of radiation.
The science behind the issues
Radiation is emitted by a source and travels in a straight line until it hits another object. When
it's absorbed, it no longer exists as radiation but heats up the absorber and may also cause
chemical changes
Some substances are radioactive. They emit ionising radiation which can cause changes within
living cells; changes which can make them grow out of control and cause cancer.
The health risks of ionising radiation increase with the dose a person receives.
As well as the risks of irradiation, people and the environment can be contaminated by
radioactive material if it spreads from its source.
What this tells us about science and society.
Experts and the general public react very differently to estimates of risk.
Often the measures used to assess the size of risk have little meaning to individuals.
People respond differently to situations where the risk is greater but the consequences are
less severe. The way people respond to risks also depends on whether or not the risk is
imposed or taken voluntarily.
Electromagnetic radiation and its effects
Light we see is a very narrow and in the broad spectrum of electromagnetic radiation from
the sun and other sources.
Eyes can see because this visible light produces chemical changes in the cells of our retinas.
These chemical changes then set off nerve signals of the brain.
Other types of electromagnetic radiation with different wavelengths can also bring about
physical and chemical changes, but our eyes cannot see them.

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Most important chemical reaction on earth is sun's radiation is photosynthesis, which
harnesses the energy from the Sun to make foods that are energy stores.
Other effects of radiation are harmful and can kill.
UV X-rays or gamma radiation is absorbed by cells, the energy carried by the radiation does
not just heat up the cells; it can also break up molecules into fragments. Molecules are
electrically neutral but some radiations can break them up into fragments which are
electrically charged.…read more

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The review emphasised that mobile phone technologies are still so we that t has not
been possible to get results from long-term epidemiological studies and evaluate
the findings.
Newer epidemiological studies
o 2007, teams from three English universities and Cancer Research UK published
results of a large four-year study of mobile phones and cancer in the British medical
journal. The researchers collected data from678 people with acoustic neruoma. In
this condition, benign tumours grow in the nerve that connects the ear to the brain.…read more

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Living close to a high voltage power line.
Pylon lines are a feature of our landscape, both in cities and in the country.
Carry electricity from power stations to consumers. Pylons carry safety warnings about the
dangers of high voltage cables, but until 1980 no one had suggested there was any other
danger from power lines. Then a study in the USA suggested a higher incidence of cases of
childhood cancer among children living near a power line.…read more

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One analysis of leukaemia cases they compared children exposed o average
magnetic fields over 0.2 microteslas with those exposed to average fields below 0.1
microteslas.
o Because of the care with which the samples were chosen and the information
collected, and the size of the study, these findings were generally felt to be more
reliable than many epidemiological studies. It was unlikely hat other environmental
factors were responsible for the results. On the other hand, the numbers of people
contracting cancers was small.…read more

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Science and technology have done much to make our lives less risky. People in the
industrialised countries live, on average, longer, healthier lives than in the past. But there are
also growing concerns that science and technology may introduce new health risks ­ from
radiation or from the chemicals used in agriculture and food processing or from industrial
wastes.
This makes it important to be able to assess how big different about whether to accept them
or try to reduce or eliminate them.…read more

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Sometimes a risk is expressed in terms of the number of people likely to experience
the event in question. For example, the population of the UK is 60 million, so the
number above suggests that around 60 people will be killed by lightning over the
next 10 year.…read more

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In one situation the factor is present and in the other it is absent, while all the other
factors that might be important are kept the same.
Detecting (or eliminating) small effects
o If factor causes a major effect, it's easy to spot and people quickly see its
importance.…read more

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There are always likely to be some difference between any tow groups. SO it is very
hard to persuade people that a factor has no effect. This involves proving a negative.
Media reports ­ genuine concern or just hype?
Reports often sensationalise new scientific claims to make them appear to be quite certain
even when they are in fact provisional, based on limited evidence, and not yet confirmed by
other scientists.…read more

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Anxieties about different sources of radiation are often completely out of proportion to the
actual risk. For example, many people are far more concerned about the radiation risk of
nuclear power stations than they are about the radiation risk in their own homes.
In fact, however, for most people the radiation risk from their own homes is far greater.
Furthermore, one very commonly held belief about radiation is incorrect- things which are
exposed to radiation from radioactive substances do not themselves become radioactive.…read more

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