Cataracts among Chernobyl Clean-up Workers: Implications Regarding Permissible Eye Exposures

Occupational health hazards in the interventional laboratory: time for a safer environment

This document is a consensus statement by the major American societies of physicians who work in the interventional laboratory environment. It reviews available data on the prevalence of occupational health risks and summarizes ongoing epidemiologic studies designed to further elucidate these risks. Its purpose is to affirm that the interventional laboratory poses workplace hazards that must be acknowledged, better understood, and mitigated to the greatest extent possible. Vigorous efforts are advocated to reduce these hazards. Interventional physicians and their professional societies, working together with industry, should strive toward minimizing operator radiation exposure, eliminating the need for personal protective apparel, and ending the orthopedic and ergonomic consequences of the interventional laboratory work environment.

Risk of cataract after exposure to low doses of ionizing radiation: a 20-year prospective cohort study among US radiologic technologists

The study aim was to determine the risk of cataract among radiologic technologists with respect to occupational and nonoccupational exposures to ionizing radiation and to personal characteristics. A prospective cohort of 35,705 cataract-free US radiologic technologists aged 24-44 years was followed for nearly 20 years (1983-2004) by using two follow-up questionnaires. During the study period, 2,382 cataracts and 647 cataract extractions were reported. Cigarette smoking for >or=5 pack-years; body mass index of >or=25 kg/m(2); and history of diabetes, hypertension, hypercholesterolemia, or arthritis at baseline were significantly (p <or= 0.05) associated with increased risk of cataract. In multivariate models, self-report of >or=3 x-rays to the face/neck was associated with a hazard ratio of cataract of 1.25 (95% confidence interval: 1.06, 1.47). For workers in the highest category (mean, 60 mGy) versus lowest category (mean, 5 mGy) of occupational dose to the lens of the eye, the adjusted hazard ratio of cataract was 1.18 (95% confidence interval: 0.99, 1.40). Findings challenge the National Council on Radiation Protection and International Commission on Radiological Protection assumptions that the lowest cumulative ionizing radiation dose to the lens of the eye that can produce a progressive cataract is approximately 2 Gy, and they support the hypothesis that the lowest cataractogenic dose in humans is substantially less than previously thought.

Eye lens exposure to radiation in interventional suites: caution is warranted

PURPOSE

To report estimated radiation doses to the eye lens of the interventionalist from procedures performed with and without use of radiation protection measures.

MATERIALS AND METHODS

Scattered radiation doses for seven interventional radiology fluoroscopic systems were measured by using phantoms simulating patients 16-28 cm in thickness undergoing low-, medium-, and high-mode fluoroscopy, cine cardiac imaging, and digital subtraction angiography (DSA). The radiation doses to the eye lens in low- and high-dose scenarios were estimated. Beam angulation, biplanar equipment, working distance, procedure complexity, imaging collimation, and use of eyeglasses and/or protective suspended screens were taken into account. The doses to the lens in several procedures were assessed.

RESULTS

Mean scattered radiation doses to the lens during fluoroscopy were 6.0 and 34.5 microSv/min in the low- and high-dose scenarios, respectively. For DSA, typical doses to the lens ranged from 0.77 to 3.33 microSv per image. Operation modes involving increasing or decreasing radiation doses were quantified. For hepatic chemoembolization, iliac angioplasty, pelvic embolization, and transjugular intrahepatic portosystemic shunt creation, lens doses ranged from 0.25 to 3.72 mSv per procedure when protection was not used. Lens doses in the neuroembolization procedures could exceed 10 mSv per procedure.

CONCLUSION

With typical reported workloads, radiation doses to eye lenses may exceed the threshold for deterministic effects (ie, lens opacities or cataracts) after several years of work if radiation protection tools are not used.

The mental health of clean-up workers 18 years after the Chernobyl accident

BACKGROUND

The psychological aftermath of the Chernobyl accident is regarded as the largest public health problem unleashed by the accident to date. Yet the mental health of the clean-up workers, who faced the greatest radiation exposure and threat to life, has not been systematically evaluated. This study describes the long-term psychological effects of Chernobyl in a sample of clean-up workers in Ukraine.

METHOD

The cohorts were 295 male clean-up workers sent to Chernobyl between 1986 and 1990 interviewed 18 years after the accident (71% participation rate) and 397 geographically matched controls interviewed as part of the Ukraine World Mental Health (WMS) Survey 16 years after the accident. The World Health Organization (WHO) Composite International Diagnostic Interview (CIDI) was administered. We examined group differences in common psychiatric disorders, suicide ideation and severe headaches, differential effects of disorder on days lost from work, and in the clean-up workers, the relationship of exposure severity to disorder and current trauma and somatic symptoms. Analyses were adjusted for age in 1986 and mental health prior to the accident.

RESULTS

Relatively more clean-up workers than controls experienced depression (18.0% v. 13.1%) and suicide ideation (9.2% v. 4.1%) after the accident. In the year preceding interview, the rates of depression (14.9% v. 7.1%), post-traumatic stress disorder (PTSD) (4.1% v. 1.0%) and headaches (69.2% v. 12.4%) were elevated. Affected workers lost more work days than affected controls. Exposure level was associated with current somatic and PTSD symptom severity.

CONCLUSIONS

Long-term mental health consequences of Chernobyl were observed in clean-up workers.

Physical dosimetry of chernobyl cleanup workers

This paper presents a critical review of dosimetric monitoring practices during Chernobyl cleanup from 1986 to 1990. Dosimetric monitoring is considered in time evolution with respect to legislative background (including dose limits), methods of dose assessment, and coverage of workers with radiation monitoring programs as well as availability of data on individual doses of liquidators. Four large independent dosimetry services (Administration of Construction No. 605, Chernobyl Nuclear Power Plant, Production Association "Combinat," and the troops) had operated in Chernobyl covering different cohorts of cleanup workers with dosimetric monitoring of variable quality and comprehension. Extremes in this range were presented by the highly professional dosimetry service of the Administration of Construction No. 605 (USSR Ministry of Medium Machinery), which had provided total coverage of workers with high quality individual thermoluminescent dosimeter monitoring, and military (troops of the USSR Ministry of Defense) who had received the least precise group dosimetry, which, however, had covered the whole population of military cleanup workers. The main groups of liquidators are considered from the point of view of completeness and quality of their dosimetric data. Main gaps in dosimetric data and limitations of existing dose records are identified. The issues of evolution of dose limits and problems of monitoring internal and beta exposure are considered from the point of view of significance of these components and the need for missing information.

Postoperative cataract cases among atomic bomb survivors: radiation dose response and threshold

Recent evidence argues against a high threshold dose for vision-impairing radiation-induced cataractogenesis. We conducted logistic regression analysis to estimate the dose response and used a likelihood profile procedure to determine the best-fitting threshold model among 3761 A-bomb survivors who underwent medical examinations during 2000-2002 for whom radiation dose estimates were available, including 479 postoperative cataract cases. The analyses indicated a statistically significant dose-response increase in the prevalence of postoperative cataracts [odds ratio (OR), 1.39; 95% confidence interval (CI), 1.24-1.55] at 1 Gy, with no indication of upward curvature in the dose response. The dose response was suggestive when the restricted dose range of 0 to 1 Gy was examined. A nonsignificant dose threshold of 0.1 Gy (95% CI, <0-0.8) was found. The prevalence of postoperative cataracts in A-bomb survivors increased significantly with A-bomb radiation dose. The estimate (0.1 Gy) and upper bound (0.8 Gy) of the dose threshold for operative cataract prevalence was much lower than the threshold of 2-5 Gy usually assumed by the radiation protection community and was statistically compatible with no threshold at all.

Dosimetry for a Study of Low-Dose Radiation Cataracts among Chernobyl Clean-up Workers

A cohort of 8,607 Ukrainian Chernobyl clean-up workers during 1986-1987 was formed to study cataract formation after ionizing radiation exposure. Study eligibility required the availability of sufficient exposure information to permit the reconstruction of doses to the lens of the eye. Eligible groups included civilian workers, such as those who built the "sarcophagus" over the reactor, Chernobyl Nuclear Power Plant Workers, and military reservists who were conscripted for clean-up work. Many of the official doses for workers were estimates, because only a minority wore radiation badges. For 106 military workers, electron paramagnetic resonance (EPR) measurements of extracted teeth were compared with the recorded doses as the basis to adjust the recorded gamma-ray doses and provide estimates of uncertainties. Beta-particle doses to the lens were estimated with an algorithm devised to take into account the nature and location of Chernobyl work, time since the accident, and protective measures taken. A Monte Carlo routine generated 500 random estimates for each individual from the uncertainty distributions of the gamma-ray dose and of the ratio of beta-particle to gamma-ray doses. The geometric mean of the 500 combined beta-particle and gamma-ray dose estimates for each individual was used in the data analyses. The median estimated lens dose for the cohort was 123 mGy, while 4.4% received >500 mGy.