Cancer Risk and Radioactive Contamination
Detection of Cancer Risk among the Population of the Radioactively Contaminated Districts of Northern Tajikistan
Tech Area / Field
- ENV-MRA/Modelling and Risk Assessment/Environment
- MED-DIS/Disease Surveillance/Medicine
3 Approved without Funding
Institute of Gastroenterology, Academy of Sciences, Republic of Tajikistan, Tajikistan, Dushanbe
- Royal Liverpool University Hospital, UK, Liverpool\nHiroshima University / Research Institute for Radiation Biology and Medicine, Japan, Hiroshima
Project summaryMalignant neoplasms all-over belong to the actual problems of public health. There are high level of cancer disease and a tendency to its growth in Northern Tajikistan. According to the data of a number of authors the death rate caused by malignant neoplasms is one of the reasons of lifetime decrease among the Northern Tajikistan population.
Retrospective analysis of the disease and the main demographics in the radioactive contamination area showed that as against 1970 there have place the sickness rate sharply increase (in certain districts in 1.8 times), the birth rate decrease in 2.6 times, general death rate increase in 1.8 times (at the age of 0-14 years birth rate increase by 127-164 %). It is indispensable to assess their sickness, the level of disability and death rate, to bring out dominant diseases and their structure as compare with control group from analog district, though not only for present time, but also in dynamics. The most important is to learn about the real inpidual absorbed dose among the population. In this connection it is necessary to carry out the epidemiological analysis of sickness and death rates cased by malignant neoplasms among the population of the district, exposed to radioactive contamination with the purpose of detection of intensity, dynamics and structure of the epidemic process, as well as detection of the specific weight of cancer morbidity, connected with residence in radioactive areas.
During examination of medical and ecological problems, connected with studying of the remote consequences of radioactive contamination in the districts, we can clearly see the number of aspects. The important problem is also investigation of the likely remote mutagenic genome abnormalities of parents and relations of these disorders with inpidual development of their descendants.
The other aspect is related with study of the remote consequences of radioactive contamination of the territory of Northern Tajikistan. Currently it is known that chronic impact of so-called “low doses” could be as dangerous as short time high dose irradiation. In this case it is not also clear how much is the inpidual absorbed dose, related with combination of external and internal body irradiations of local population in Taboshar area including their descendants, inhabiting in radionuclide contaminated territories. Here it is also more difficult to find the solution of the concerns, related with demonstration analysis of remote mutagenic and genotoxic small dose irradiation effects on the development of children, living in impacted districts. It is very important to assess the possible immune statuses decrease among the local population and especially among the children of different ages in radioactively contaminated areas. It is also necessary to carry out the detailed environmental survey of the impacted territories of Taboshar including study of local radionuclide contamination, to localize and outline threatened area and carry out further radioecological monitoring of the environment. The goal of the project is: appraisal of the effect of chronic ionizing irradiation on the health of people living on radioactive contaminated territories of the Northern Tajikistan (Taboshar town), knowledge level increase of the local population by carrying out seminars, publication of booklets and development of natural bioactive medicines, stimulating removal of radioactive substances out of body and increasing body stability to ionizing radiation impact.
Dose appraisal of population living in close proximity to uranium ore and radioactive wastes reprocessing enterprise is based on gamma background level measuring: a) in radioactive wastes burial place; b) in separate areas of villages; c) inside of houses. In order to assess the environmental radioactive contamination level we shall take samples for determination of 238U and 232Th content in soil and plants. On the basis of these measurements we shall develop the average external irradiation doses (M.O. Degteva, 1994). On the basis of the results of these measurements and using the developed age model (M.M. Kossenko and others 1999) we shall calculate the average dose of internal irradiation among the certain age groups of population. The available information on radiation dose is not sufficient for detection of risk group. In this connection we shall evaluate the radiation doses of population caused by entering of radioactive substances in human body along with main food products (milk, wheat, potato and etc.). In order to implement the long-term observations of radiation-exposed people and to organize epidemiological investigations we shall prepare information on four main directions:
- Creation and continual supplement of the register of radiation-exposed people. The register of radiation-exposed population was created in 1965 in the Northern Tajikistan and during those years the population was not given passports.
- Information collection about permanent radiation effect (specifically, about progress and verification of cancer diagnoses). We shall select the territories where during the whole monitoring period will be recorded lives, all death and cancer cases of radiation exposed people. The monitoring zone (Taboshar town) consists of three administrative districts. Total quantity of population is about 7 thousand people. We shall use two sources of information: a) information about first detected cancer hematological diseases, which are registered by statistic groups of the Khujand cancer prophylactic center, the Republican research oncology center in Dushanbe and hematology department of Sugd region about the cases of leukemia and solid cancer cases among the people inhabiting very close to the uranium ores and radioactive wastes reprocessing enterprise.
- Control selection. During the radiation effect analysis for 30 monitoring years as the control group will be considered the group of population, which did not undergo radiation, but which lives in the same administrative districts – so-called regional control. Death rate and the cancer risk value will be detected using the registry control method.
- Statistic analysis method choosing. The cohort analysis methods shall be used for epidemiological analysis of tumor response. Data shall be processed using the software EPICURE (Preston D.L. et al., 1993) and grouping by the following categories: sex, ethnic group, radiation dose, age at the moment of the first exposure and for the moment of death. This software, unlike other ones, allows regularities determination at Pausson distribution. In addition, this software was used for risk assessment of the people, who survived atomic bombing.
It is important to note that haemopoiesis and immunity belong to the most radiosensitive organism systems and their quantitative and qualitative indicators are to some degree the markers for radiation injury degree assessment. We shall investigate the immunity state for evaluation of the health state, course and prognosis of the different diseases’ outcomes, first of all cancer diseases. According to the data of many authors (A.B.Knizhnikov, 1988, 1992) the food products impact into internal radiation dose makes 98-99%, from them milk- 80%, meat –10%, potato- 6%, vegetables –6%, bread-4%. In this connection arises a problem of population radiation dose decrease. In the project the aspects of the problem will include the following:
- setting of permissible contamination level for food and feedstock;
- food products contamination level control;
- development of the medicines, products and food supplements, decreasing absorption and accumulation of radioactive nuclides and (or) increasing organism resistance to the effect of ionizing radiation using as the source the local plants and vegetation.
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