UNDER RADIATION

It was thought until recently that exposure to radiation is harmful for human beings. However, a recent study by scientists at Oxford University, published at Newsland, showed that people can be more resistant to radiation than was believed. Over the past 50 years, developments in clinical medicine, radio-biology and accidents like that at the Chernobyl nuclear plant in 1986 have helped scientists to improve their knowledge of X-ray irradiation. The fate of 237 fire fighters who were irradiated in the first days after the Chernobyl accident proved that a high single dose of irradiation is fatal. Some 28 fire fighters died just weeks after the accident, 27 of them received doses exceeding 4 Sv (1 Sv equals about 100 Roentgen).

The devil is not so dreadful…

But many people can be exposed to higher doses, albeit in different circumstances, say the Oxford scientists. In radiotherapy treatment, for example, a cancerous growth dies from a dose exceeding 40 Sv. During such treatment the healthy tissue around a cancerous growth is exposed to 20 Sv, which is 2,000 times higher than the recommended annual limit and at least five times higher than the fatal dose to which the Chernobyl fire fighters were exposed. To survive this dosage, a patient receives state-by-stage radiotherapy treatment over four to six weeks. Healthy tissues receive about 1Sv every day and manage to recover, whereas cancerous cells are given higher doses and they die.

What are the long-term consequences of radiation exposure? Data from Hiroshima and Nagasaki showed that radiation-damaged cells cause cancer on rare occasions. The data showed that 7.9 per cent of those who survived the bombing had died of cancer by the year 2000. In the same period, 7.5 per cent of people of similar age died of cancer in other parts of Japan. The data shows that the risk of cancer from exposure to radiation is very small compared to other carcinogens. Those exposed to a dose lower than 0.1 Sv have a low risk of developing leukaemia, heart diseases or pregnancy problems. 0.1 Sv is a safe single dose of radiation exposure. The human body has developed the ability to heal itself during evolution and this makes it possible to increase a single exposure dose to 5 Sv, with a monthly radiation exposure not exceeding 0.1 Sv. 

Currently, the recommended ceiling for radiation exposure is 1 mSv per year; in addition to background radiation, this totals about 2.5 mSv. For comparison, a CT scan produces a dose of 5 mSv and a roentgenogram produces one hundredth of that. 

There is a grain of truth, but…

Adil Qaribov, director of the Radiation Research Institute at Azerbaijan's Academy of Sciences, told R+ that, following the study by the Oxford University scientists, the generally recognized norm for radiation may be increased 1,000-fold. Moreover, the new data may calm a public which now fears any source of radiation. This may also change the approach to nuclear waste, which is less harmful to the biosphere than carbonic gas emissions and oil spills.

Nevertheless, the impact of radiation on the environment is a global problem requiring special attention - despite the recent scientific conclusions and numerous studies, there has still not been sufficient study of this area. "It was believed until today that artificial isotopes are the main sources of radioactive impact on the environment. But scientists have also established that in addition to nuclear explosions and nuclear plant accidents, tectonic processes and human activity can cause radioactive pollution," says Qaribov. He believes that radioactive pollution of the environment should be strictly monitored and supervised. As to background radiation, this is a natural phenomenon affecting all organisms. It should not exceed approved norms, as it may have irreversible consequences.

Tectonic processes, space and the sun are sources of background radiation, but rocks are the main sources. Qaribov cited the United Nations Scientific Committee on the Effects of Atomic Radiation, which said that tectonic processes produce up to 83 per cent of the annual effective equivalent of the radiation dose that people receive. Although the quantity is small, artificial sources of ionizing radiation add to it.

The problem is quite important for Azerbaijan, especially on the Absheron peninsula, where the country's oil and industry are based. The 80-year-long development of onshore and offshore oil and gas fields has informed the area's radiation climate. According to Qaribov, studies by the Geology Institute of Azerbaijan's Academy of Sciences showed that the situation concerning radiation on the peninsula is generally normal, with a natural background radiation of 6 microroentgens per hour. At some oil fields radiation is ten times or more higher than the ceiling, due to accumulated oil production waste. 

Radon - a gas which radioactive substances discharge as they decay - is quite radioactive. It may accumulate in large amounts in the basements of residential buildings and make its way into living quarters. This is why it is very important to check all imported building materials for radon.

Thorough checks

Qaribov says that the Isotope Specialist Centre within the Emergencies Ministry deals with the transportation, processing, recycling and storage of radioactive waste in the country. The centre also deals with the decontamination of special uniforms at areas and enterprises that use radioisotope devices. It also carries out radio-ecology monitoring, which includes sample testing, gamma testing and gamma spectrometric tests. Anyone can ask the centre to check his house for ionizing isotopes. There are many organizations in the Absheron peninsula which use sources of radiation and centre employees often work in contaminated areas close to residential buildings, says Qaribov. Thus the centre checks all oil fields in the peninsula to find and neutralize threats of radiation.

 No measures were taken to improve the radioecological situation in the country until the law "On radiation security" was passed in 1997. In 2006, President Ilham Aliyev approved a programme of measures aimed at improving the environmental situation in the country from 2006-11. Under the programme, the Radiation Research Institute, the gamma-ray spectrometry department of the Geology Institute and the Isotope Centre are working to improve radioecological conditions in affected areas. For example, considerable work was done - jointly with the environment monitoring department of the State Oil Company - to clear the oil fields in Bibiheybat. 

Qaribov said that practising experts are working in close cooperation with theorists. Studies by scientists from the Geology Institute were used to prepare a scheme for radioecological monitoring in the country. Now, prior to starting the development of new offshore fields, geological and hydro-geological tests are carried out to ascertain the concentration of radioactive nuclides in water and bottom sediments. This facilitates forecasts of the dangers of radioactive nuclide pollution of the sea. In addition, ionizing radiation is checked in test areas and danger zones are identified. These zones are then certified and proposals are prepared for clearing contaminated zones. Qaribov said that every oil field is a source of ionisation - sometimes within and sometimes above accepted norms - and relevant recommendations are prepared for each case to reduce the impact of radiation on people.