Chronic low-dose exposure in the Techa River Cohort: risk of mortality from circulatory diseases

Abstract

The aim of the present study was to analyze the mortality from circulatory diseases for about 30,000 members of the Techa River cohort over the period 1950-2003, and to investigate how these rates depend on radiation doses. This population received both external and internal exposures from (90)Sr, (89)Sr, (137)Cs, and other uranium fission products as a result of waterborne releases from the Mayak nuclear facility in the Southern Urals region of the Russian Federation. The analysis included individualized estimates of the total (external plus internal) absorbed dose in muscle calculated based on the Techa River Dosimetry System 2009. The cohort-average dose to muscle tissue was 35 mGy, and the maximum dose was 510 mGy. Between 1950 and 2003, 7,595 deaths from circulatory diseases were registered among cohort members with 901,563 person years at risk. Mortality rates in the cohort were analyzed using a simple parametric excess relative risk (ERR) model. For all circulatory diseases, the estimated excess relative risk per 100 mGy with a 15-year lag period was 3.6 % with a 95 % confidence interval of 0.2-7.5 %, and for ischemic heart disease it was 5.6 % with a 95 % confidence interval of 0.1-11.9 %. A linear ERR model provided the best fit. Analyses with a lag period shorter than 15 years from the beginning of exposure did not reveal any significant risk of mortality from either all circulatory diseases or ischemic heart disease. There was no evidence of an increased mortality risk from cerebrovascular disease (p > 0.5). These results should be regarded as preliminary, since they will be updated after adjustment for smoking and alcohol consumption.

Biological Effectiveness of Ionizing Radiation: Acute vs. Protracted Exposures

“…and digestive systems, was reported in [22], which can be seen as circumstantial evidence in favor of dose-related differences in medical surveillance and self-reporting, a phenomenon noticed also by other researchers in populations exposed to radiation [28], discussed in [29]. In the author's opinion, the dose-effect relationships with non-neoplastic diseases [30][31][32][33][34] call in question such relationships with cancer, reported e.g. in the studies [23,24,[35][36][37][38][39][40][41][42][43] including those cited in [2,25] in support of the DDREF lowering.…”

“…Although there may be some risk of cardiovascular disease at high dose and dose-rate exposures [16], existing data are insufficient to confirm a cause-effect relationship between radiation and cardiovascular diseases at doses below 1-2 Gy, while plausible biological mechanisms are unknown [44]. Average doses in the epidemiological studies [30][31][32][33][34] were lower. As mentioned above, people knowing their relatively high dose estimates would probably be on average more motivated to visit medical institutions (self-selection bias), being at the same time given more attention.…”

Low dose radiation and circulatory diseases: a brief narrative review

“…A study of a cohort of environmentally exposed individuals in the Southern Ural Mountains reported a statistically significant, or borderline significant, increase (depending on the latent period used) of both all circulatory disease mortality, with an ERR of 0.24 Gy −1 (95 % CI, −0.08 to 0.59), and IHD mortality, with an ERR of 0.40 Gy (95 % CI, −0.11 to 0.99) with a 10-year lag [35]. The Table 1 Estimated excess relative risks of circulatory disease in various studies of moderate-and low-dose radiation exposure.…”

“…The Table 1 Estimated excess relative risks of circulatory disease in various studies of moderate-and low-dose radiation exposure. (Adapted from Little et al [11,12] Chernobyl emergency workers Ivanov et al [22] 0 Analysis using underlying or contributing cause of death c Analysis based on stomach dose, derived from Table 4 of Yamada et al [20] with smoking and drinking in the stratification d Risk estimates in relation to cumulative whole body external gamma dose; doses given here are from Moseeva et al [24] e Assuming a lag period of 10 years f 90 % CI g Estimate derived from log-linear model, evaluated at 1 Sv h Analysis based on dose to muscle trends were statistically significant (P ≤ 0.05) with lags of 15 to 20 years, but not significant (P > 0.1) with lags of 0 to 10 years [35].…”

Cumulative doses analysis in young trauma patients: a single-centre experience

“…In particular, it is well known that high doses (>5 Gy) of ionising radiation exposure produce damage to the heart and coronary arteries. In recent years, many studies have investigated cardiovascular diseases [20][21][22][23][24][25][26], proposing that doses higher than 0.5 Sv cause an excess relative risk [22,23]. This excess relative risk is calculated on 5 % per mSv [23].…”