If you are of a certain age, you might just remember when xray machines were standard in many shoe shops. You put your feet in your new shoes and then stood on the machine and the xray showed you where your bones were and how much “growing room” there was for young feet.
It wasn’t long before research on radiation confirmed that being exposed to high levels of radiation could be very dangerous and these foot xray machines were quickly withdrawn.
However, in our daily life we are still all exposed to varying levels of radiation and the terrible problems in Japan have highlighted the dangers of radiation in our lives.
But how much radiation is too much? First, it is important to realise that radiation is a very loose term for different activity. Most people when talking about radiation are talking about ionising radiation, a type that is made up from high energy waves and in high doses can cause serious health problems such as burns, sickness, cancer and death.
This is because our DNA (the genetic material in cells) is especially sensitive to ionising radiation which can change its structure.
This sort of radiation is part of our natural as well as our manmade world. For instance, we are exposed to cosmic radiation and also to radiation from the natural gasses radon and thoron. Radon is made from the natural decay of uranium and thorium in the soil and leaches out into the atmosphere. Some areas are much more affected by radon than others and it can be useful to check out the levels where you live.
Stone or brick homes will have natural radioisotopes in them which will give off some radiation; brazil nuts are known to be a “radioactive” food because of their high radium content; radiation can come from uranium which is often added to crowns and bridges in dental products for an added level of whiteness. Even air travel can slightly increase your exposure – above 30,000 feet and you are closure to ionising radiation.
But while scare stories are sometimes written about our natural exposure to radiation, in fact we have been living with it since the first man rose up onto two legs. In normal life, the level of radiation we receive will have minimal effect on our health.
It is only when high doses are received that the problems start, so it is important to know how radiation is measured. There are a number of measurements used when talking about radiation including millirems, sieverts, millisieverts and microsieverts. Probably the words you will hear most are millisieverts and microsieverts. One millisievert (mSv) is equal to 1,000 microsieverts. These indicate the amount of radiation absorbed by human tissues.
There are many varying figures, but generally it is said that people are exposed on average to around 2 to 3 millisieverts a year through exposure to natural radiation. Figures suggest that exposure to 100 millisieverts a year is the lowest level at which any increase in cancer risk is evident. Therefore there clearly is considerable leeway every year to absorb radiation from manmade aspects without fear.
That said, figures do vary and it is worth having some idea of your level of exposure if you are undergoing a series of medical treatments. This isn’t as easy to work out as it sounds because there are a number of factors that needs to be taken into account, including the fact that different organs in our body will absorb differing levels of radiation. The thyroid gland and bone marrow are particularly sensitive to ionising radiation. In x-rays, for instance, levels of radiation exposure from an x-ray of the spine could be in the region of 1.5 mSv, while a chest x-ray could be 0.1 mSv and a mammography 0.4 mSv. A CT scan could be considerably higher. There has been talk of problems from flying, but figures suggest a flight from say New York to Los Angeles will increase radiation exposure by 0.03 to 0.04 microsieverts, again a very small figure indeed in the overall scheme of things.
When you see media reports of problems from nuclear sites stating figures of 400 mSvs and more, it gives some indication of the variation between serious radiation leaks and the levels of radiation found in our normal lives.
Radiation is not all bad – thousands are treated across the world every year with radiation therapy to shrink tumours and kill cancer cells – almost half of all cancer patients receive some type of radiation therapy at some point during their treatment. Thanks to details research and increasing knowledge, doctors today have full information of what parts of the body can safely receive certain levels of radiation and this is an important aspect of determining the best treatment.
It is all about knowledge. Scientists today understand far more about nuclear energy than they did in the days of the Three Mile Island incident or even Chernobyl; no doubt the terrible problems encountered in Japan will also increase knowledge and expertise. Radiation has been part of our lives forever and the more we know about it the better we will understand its consequences and its potential benefits as well.
Share on Facebook
Receive more like this