Recent Publications by CFE Educators

Relatively few data are available on the prevalence of hyperthyroidism (TSH concentrations of 0.3 mIU/liter, with normal or elevated concentrations of free T4) in individuals exposed to radioiodines at low levels. The accident at the Chornobyl (Chernobyl) nuclear plant in Ukraine on April 26, 1986 exposed large numbers of residents to radioactive fallout, principally to iodine-131 ((131)I) (mean and median doses  =  0.6 Gy and 0.2 Gy). We investigated the relationship between (131)I and prevalent hyperthyroidism among 11,853 individuals exposed as children or adolescents in Ukraine who underwent an in-depth, standardized thyroid gland screening examination 12-14 years later. Radioactivity measurements taken shortly after the accident were available for all subjects and were used to estimate individual thyroid doses. We identified 76 cases of hyperthyroidism (11 overt, 65 subclinical). Using logistic regression, we tested a variety of continuous risk models and conducted categorical analyses for all subjects combined and for females (53 cases, n  =  5,767) and males (23 cases, n  =  6,086) separately but found no convincing evidence of a dose-response relationship between (131)I and hyperthyroidism. There was some suggestion of elevated risk among females in an analysis based on a dichotomous dose model with a threshold of 0.5 Gy chosen empirically (OR  =  1.86, P  =  0.06), but the statistical significance level was reduced (P  =  0.13) in a formal analysis with an estimated threshold. In summary, after a thorough exploration of the data, we found no statistically significant dose-response relationship between individual (131)I thyroid doses and prevalent hyperthyroidism.

The contraceptive vaginal ring is a relatively new combined hormonal contraceptive method. Ethinyl estradiol and etonogestrel are rapidly absorbed through the vaginal epithelium and result in a steady serum concentration. Studies have demonstrated that the efficacy and safety of the ring are equivalent to oral contraceptives (OCs). Patients report being highly satisfied with the vaginal ring and report fewer systemic side effects than do OC users. The ring provides effective cycle control as well as symptom relief for women with menorrhagia, dysmenorrhea and polycystic ovarian syndrome. A new combined contraceptive ring containing Nestorone and ethinyl estradiol is currently being investigated in a Phase 3 trial. A progesterone-releasing vaginal ring appropriate for lactating women is available in Chile and Peru. Recent studies have demonstrated that vaginal rings can also be effective means of delivering antiretroviral drugs that provide protection from HIV.

This study assessed the relationship between radon decay product (RDP) exposure and mortality and cancer incidence in a cohort of 17,660 Eldorado uranium workers first employed in 1932-1980 and followed up through 1999. The analysis was based on substantially revised identifying information and dosimetry for workers from the Beaverlodge and Port Radium uranium mines and for the first time includes workers from a radium and uranium refinery and processing facility in Port Hope, Canada. Overall, male workers had lower mortality rates of all causes and all cancers and lower incidence rates of all cancers compared with the general Canadian male population, a likely healthy worker effect. Individual cancer rates were also reduced except for lung cancer mortality (SMR  =  1.31, P 0.001) and incidence (SIR  =  1.23, P 0.001). The excess relative risk per 100 WLM (ERR/100 WLM) of lung cancer mortality (N  =  618, ERR/100 WLM  =  0.55, 95% CI: 0.37, 0.78, P 0.01) and incidence (N  =  626, ERR/100 WLM  =  0.55, 95% CI: 0.37, 0.81, P 0.001) increased linearly with increasing RDP exposure. Adjustment for effect modification by time since exposure, exposure rate and age at risk resulted in comparable estimates of risk of lung cancer for all three uranium worksites. RDP exposures and γ-ray doses were not associated with any other cancer site or other cause of death. The risk estimates are in agreement with the results of the pooled analysis of 11 miner cohorts and more recent studies of uranium workers. The current analysis provides more precise risk estimates and compares the findings from the mortality study with the incidence study. Future follow-up of the cohort and joint analysis with other uranium miners' studies should shed more light on the effects of low RDP exposures as experienced by current workers as well as help to understand and address the health risks associated with residential radon.