Background: Although high doses of ionizing radiation have long been linked to circulatory disease, evidence for an association at lower exposures remains controversial. However, recent analyses suggest excess relative risks at occupational exposure levels.Objectives: We performed a systematic review and meta-analysis to summarize information on circulatory disease risks associated with moderate- and low-level whole-body ionizing radiation exposures.Methods: We conducted PubMed/ISI Thomson searches of peer-reviewed papers published since 1990 using the terms “radiation” AND “heart” AND “disease,” OR “radiation” AND “stroke,” OR “radiation” AND “circulatory” AND “disease.” Radiation exposures had to be whole-body, with a cumulative mean dose of < 0.5 Sv, or at a low dose rate (< 10 mSv/day). We estimated population risks of circulatory disease from low-level radiation exposure using excess relative risk estimates from this meta-analysis and current mortality rates for nine major developed countries.Results...

Incidence of and mortality from cardiovascular diseases have been studied in a cohort of 12,210 workers first employed at one of the main plants of the Mayak nuclear facility during 1948–1958 and followed up to 31 December 2000. Information on external γ-ray doses is available for virtually all of these workers (99.9%); the mean total γ-ray dose (±SD) was 0.91 ± 0.95 Gy (99% percentile 3.9 Gy) for men and 0.65 ± 0.75 Gy (99% percentile 2.99 Gy) for women. In contrast, plutonium body burden was measured for only 30.0% of workers; among those monitored, the mean cumulative liver dose from plutonium alpha exposure (± SD) was 0.40 ± 1.15 Gy (99% percentile 5.88 Gy) for men and 0.81 ± 4.60 Gy (99% percentile 15.95 Gy) for women. A total of 3751 cases of ischemic heart disease (IHD), including 683 cases of acute myocardial infarction (AMI), and 1495 IHD deaths, including 338 AMI deaths, were identified in the study cohort during the follow-up period. Having adjusted for non-radiation factors, there were statistically significant increasing trends with both total external γ-ray dose and internal liver dose in IHD incidence. The trend with internal dose was weaker and was not statistically significant after adjusting for external dose, whereas the external dose trend was little changed after adjusting for internal dose. The trend with external dose in IHD mortality was not statistically significantly greater than zero but was consistent with the corresponding trend in IHD incidence. The estimated trend in IHD mortality with internal dose was lower and was not statistically significant once adjustment was made for external dose. There was a statistically significantly increasing trend in AMI incidence but not AMI incidence with external dose. The risk estimates for IHD in relation to external radiation are generally compatible with those from other large occupational studies and the Japanese A-bomb survivors.

The International Commission on Radiological Protection (ICRP) has considered for over 60 years that the lens of the eye is among the most radiosensitive tissues, and has recommended dose limits for the lens to prevent occurrence of vision impairing cataracts (VICs). Epidemiological evidence that doses much lower than previously thought produce cataracts led ICRP to recommend reducing dose threshold for VICs and reducing an occupational equivalent dose limit for the lens in 2011, when only a single threshold of 0.5 Gy was recommended. On the basis of epidemiological evidence, ICRP assumed progression of minor opacities into VICs and no dose rate effect. This contrasts with previously recommended separate thresholds for minor opacities and VICs, and for different exposure scenarios. Progression was assumed based on similar risks of cataracts and cataract surgery in Japanese atomic bomb survivors. The absence of dose rate effect derived from the observed similar thresholds for protracted exposures in Chernobyl cleanup workers and in atomic bomb survivors. Since 2011, there has been an increasing body of epidemiological evidence relating to cataracts and other ocular diseases (i.e. glaucoma and macular degeneration), particularly at low doses and low dose rates. This review paper gives an overview of the scientific basis of the 2011 ICRP recommendation, discusses the plausibility of these two assumptions in the light of emerging scientific evidence, and considers the radiosensitivity of the lens among ocular structures.