Issues in the Comparison of Risk Estimates for the Population in the Techa River Region and Atomic Bomb Survivors

Abstract

Plutonium production in the former Soviet Union began in 1949 at the Mayak Production Association located between the cities of Chelyabinsk and Ekaterinbourg in the southern Ural mountains about 1200 km east to Moscow. During the first few years of Mayak's operation, almost 30,000 people living on the banks of the Techa River received significant internal and external exposures as a consequence of the release of large quantities of radioactive materials from Mayak. Studies of levels of radioactive contamination and health effects in this population began in the early 1950s. A systematic follow-up of a fixed cohort that includes all people who were living in Techa River villages in 1949 was begun about 30 years ago. In this paper we describe the Techa River cohort, outline the nature of the exposures and discuss the status of follow-up for the period from 1950 through 1989. While noting the limitations of the current epidemiological follow-up data, we also compare the demographic and mortality structure of the Techa River cohort with the Life Span Study cohort of Japanese atomic bomb survivors. It is seen that, despite a number of limitations, the current data suggest that the risks of mortality from leukemia and other cancers increase with increasing radiation dose in the Techa River cohort. This finding suggests that, with continued improvements in the quality of the follow-up and dosimetry, the Techa River cohort has the potential to provide quantitative estimates of the risks of chronic low-dose-rate radiation exposures for an unselected general population that will be an important complement to the estimates based on the Life Span Study that are used as the primary basis for numerical assessments of radiation risk.

Fractionated Low-Dose Radiation Exposure Leads to Accumulation of DNA Damage and Profound Alterations in DNA and Histone Methylation in the Murine Thymus

“…Radiation-induced leukemia in humans was first reported early in the 20th century (1)(2)(3)(4). Since then, numerous studies of atomic bomb survivors, people working or living near nuclear power plants, radiologists, and radiotherapy patients have shown that certain doses of both acute and fractionated radiation exposure result in a high risk of leukemia and lymphoma (1)(2)(3)(4)(5)(6)(7). Furthermore, the risk of secondary radiation treatment-related lymphoma and leukemia is a clinical problem (6).…”

Immune System Modifications Induced in a Mouse Model of Chronic Exposure to90Sr

“…The combined exposure studies are not suitable for the derivation of MRLs. An increase in the incidence of leukemia was reported for Techa River individuals receiving estimated bone marrow doses, attributed to radioactive strontium, in excess of 10 rem (0.1 Sv) (Kossenko 1996;Kossenko et al 1997Kossenko et al , 2000Kossenko et al , 2002. Dystrophic lesions of the skeleton were observed in individuals with mean radiation doses to the surface of bone in excess of 200 rem (2 Sv) (Akleyev et al 1995).…”

“…In contrast, the Techa River population that was exposed to contaminated water and food as a result of releases from a nuclear weapons facility exhibited a significant increase in the incidence of leukemia (Kossenko 1996;Kossenko et al 1997Kossenko et al , 2000Kossenko et al , 2002. An excess of leukemia cases (0.85 excess cases per 10,000 person-year Gy (95% CI: 0.2; 1.5) was observed in groups of individuals with estimated bone marrow doses in excess of 10 rem (0.1 Sv), and the risk of mortality from leukemia increased with increasing dose (Kossenko, 1997(Kossenko, , 2002.…”

“…An excess of leukemia cases (0.85 excess cases per 10,000 person-year Gy (95% CI: 0.2; 1.5) was observed in groups of individuals with estimated bone marrow doses in excess of 10 rem (0.1 Sv), and the risk of mortality from leukemia increased with increasing dose (Kossenko, 1997(Kossenko, , 2002. This finding can be related to the body burdens of 90 Sr, which in the Techa River cohort, have been >100 times higher than fallout-related exposures during the same period (Shagina et al 2000).…”

“…Dosimetry data are available for approximately 16,000 members of the Techa River population that was exposed to radiostrontium because of releases from a plutonium processing plant between 1949 and 1956 (Kossenko et al 1997). Since exposure levels in this population were 30-100 times higher than the maximum exposure from global fallout, this cohort represents the largest group of subjects available for examining health effects of chronic radiation exposure.…”