"Radiation & Risk", 2004, special issueChapter 1CANCER INCIDENCE AMONG NUCLEAR WORKERS IN RUSSIA BASED ON DATA FROM THE INSTITUTE OF PHYSICS AND POWER ENGINEERING: A PRELIMINARY ANALYSISIvanov V.K.1, Tsyb A.F.1, Rastopchin Eu.M.1, Gorski A.I.1, Maksioutov M.A.1,Vayzer V.I.2, Suspitsin Yu.V.3, Fedorov Yu.V.31 Medical Radiological Research Center of Russian Academy of Medical Sciences, Obninsk;2 Institute of Physics and Power Engineering, Obninsk;3 Medical Units of ObninskOne group that has the potential to be exposed to radiation is workers in the nuclear industry. Results of a systematic medicalfollow-up and dosimetric monitoring of these workers can form the basis for a study of the relationship between cancer incidenceand radiation dose. As part of such efforts in Russia, a major institution of the nuclear industry was selected with an establishedmedical care unit, archiving capabilities and dosimetry department: the Institute of Physics and Power Engineering (IPPE) inObninsk. In the study a comparative analysis of cancer incidence rates for the IPPE workers and for the general population ofRussia in 1991-1997 was carried out. The subjects were the IPPE workers hired before 1981. This restriction was imposed toreduce the uncertainty associated with the possible latent period in the development of solid cancers. Thus the possibility ofincluding persons who already had the disease at the time when they were hired was minimized. The analysis is based oninformation about 158 cancer cases, including 24 cancers in persons under individual dosimetric monitoring. A statisticallysignificant excess in cancer incidence was found among the IPPE workers compared with a comparison population (the generalpopulation of Russia) for some types of cancers. The SIR values for all cancers (ICD-9: 140-208) is 0.93 (0.76, 1.12 95% CI) formales and 1.42 (1.06, 1.87 95% CI) for females. A statistically significant excess for all cancers was also observed for residentsof Obninsk compared to the control comparison population. The corresponding SIR value was 1.20 (1.12, 1.28 95%CI) for malesand 1.58 (1.49, 1.69 95% CI). An important reason for the observed excess in cancer incidence compared to the controlpopulation may be the higher level of health care in the so-called nuclear cities of Russia which may have resulted in increaseddiagnosis and registration of cancers. However a statistically significant dependence of the cancer incidence on the dose ofionizing radiation was not established. The excess relative risk per 1 Gy for all types of cancer was 0.91 (-2.75, 4.61 95% CI) formales and 0.40 (-6.94, 7.83 95% CI) for females. These estimates should be considered to be preliminary, as the number ofcases considered in the analysis of the dose response is small (17 males and 7 females).IntroductionThe study of the health status of nuclear workers has at least two aspects:1. Assessment of the health status by comparing the incidence rates for different diseases among the nuclearworkers and the general population.2. Direct estimation of the relationship between incidence rates and chronic and relatively low radiationdoses.The first task requires a knowledge of the sex and age factors related to the incidence of diseases in thestudy group and the general population, as well as demographic data about the nuclear workers. In the second case,the dose and the chronology of radiation exposure are needed for each worker in addition to the medical information(incidence rates).5"Radiation & Risk", 2004, special issueFor cancers, the dose dependences of incidence rates and mortality have been derived in terms of radiationrisks for atomic bomb survivors and for patients exposed to radiation for therapeutic purposes [1-5]. Theseestimates of radiation risks, however, were made for relatively high doses and dose rates. Exclusion of high doses(more than 0.2-0.5 Sv) from the study of cancer incidence in the Japanese cohort leads to a significant change inthe dose dependence of cancer incidence [6]. In this sense, the cohort of the Chernobyl emergency workers(average dose 0.1 Sv) is somewhat intermediate in the estimation of radiation risks [7]. It should be noted thatradiation risks from exposure to low doses and low dose rates are estimated using different extrapolation methods[2], which involve significant uncertainties.Direct estimates of the effects of chronic low radiation doses on the development of cancer can be obtainedby studies of cancer incidence among workers in the nuclear industry. A study of the dose dependence of cancerincidence should be based on systematic specialized medical follow-up and dosimetric monitoring of the subjects.Such research is being carried out in the USA [8], Canada [9], UK [10] and other countries. To take advantage of theaccumulated experience from these studies, international projects involving many countries have also been initiated[11].In Russia large-scale radiation epidemiological projects on the effects of radiation on the health of nuclearworkers have not been undertaken, with the exception of studies of the workers at the «Mayak» plant [12]1.In the present paper the issues related to cancer incidence among the personnel of the Institute of Physicsand Power Engineering (IPPE), Obninsk, Russia, are discussed. The cancer incidence rates in the IPPE workers andthe general population of Russia are compared and the dependence of the incidence of different cancers on radiationdose is estimated.Materials and methodsGeneral information about IPPEAfter the nuclear weapons tests of the 1940s and 1950s the former USSR started developing both militarytechnologies and building nuclear facilities and nuclear power plants. In 1946 Laboratory «B» of the USSR Ministryof Internal Affairs was set up not far from Moscow. Although the activities of the laboratory were classified, they weredirected at solving the scientific and technical problems associated with the development of nuclear power andtechnology. The first nuclear power plant was built at the same location in 1954 and the IPPE was set up later onthis base.Today the laboratory of the State Research Center of Russian Federation IPPE in Obninsk, which is 100 kmfrom Moscow, is one of the largest centers of nuclear science and technology in the country. The Institute conductsstudies in nuclear