Low-dose ionizing radiation and cancer mortality among enlisted men stationed on nuclear-powered submarines in the United States Navy

BACKGROUND

Men stationed on nuclear-powered submarines are occupationally exposed to external ionizing radiation at very low levels and radiation dose for each individual is closely monitored. Little is known about ionizing radiation (IR) risks of cancer mortality for populations with levels of cumulative ionizing radiation exposure this low.

MATERIALS AND METHODS

This historical cohort study followed 85,033 enlisted men who had served on a nuclear-powered submarine in the U.S. Navy between 1969 and 1982 to determine patterns of cancer mortality. Occupational radiation doses were measured by badge dosimeters for each individual for all periods of Navy service potentially involving radiation exposure. Deaths were ascertained through 1995 by searches of multiple national mortality databases. Within-cohort dose-response relationships for cancer mortality were estimated using linear Poisson regression models. Individual level smoking status was not available so cancer risks were estimated separately for cancers with and without previously published evidence of consistently moderate or strong associations with smoking.

RESULTS

A total of 584 cancer deaths occurred during a follow-up period of up to 27 years. The mean and median cumulative occupational radiation doses received while in the Navy were 5.7 and 1.1 milliSieverts (mSv) respectively, range 0-242 mSv. Mortality Excess Relative Risks (ERRs) per 10 mSv and 95% confidence intervals (CI) were 0.053 (CI -0.03, 0.17) for all cancers, 0.052 (CI -0.03, 0.18) for all solid cancers, and 0.003 (CI -0.29, 0.30) for leukemias excluding chronic lymphocytic leukemia. The ERRs per 10 mSv were 0.052 (CI -0.07, 0.17) for cancers previously associated with smoking and 0.012 (CI -0.10, 0.12) for cancers that were not.

CONCLUSIONS

The ERR point estimates for solid cancers and leukemia were statistically compatible with those reported in previous published studies of other ionizing radiation-exposed and monitored cohorts, albeit with wide confidence intervals. This study, with high quality measurements of in-Navy occupational external IR doses, high follow-up proportion, and detailed IR dose-response analyses, is consistent with the premise of a small excess cancer risk from low-dose IR.

7-year results of primary total hip arthroplasty with the uncemented Avenir stem

AIMS

The aim of the present study was to evaluate the 7-year functional outcome and radiographic results of primary total hip arthroplasties (THAs) performed with the uncemented Avenir stem.

PATIENTS AND METHODS

Between January 2006 and October 2008, 100 consecutive primary hips in 92 patients were enrolled at 2 centres. The mean age at operation was 58.5 years (27-87 years). Mini-incision (50%) and standard approaches (50%) were used to implant 22 standard and 78 lateralised stems.

RESULTS

The 7-year Kaplan-Meier survival rate was 98.9% (95% CI, 92.9-99.8) with stem revision for any reason as endpoint. No stem related complications occurred. 1 stem revision was due to deep infection at 51 months post-op. We had 4 acetabular revisions. The mean Harris Hip Score (HHS) at 7 years follow-up was 93.1 points (60-100). Radiographic analysis showed 2 patients had non-progressive radiolucent lines and no patient had any signs of stem subsidence or loosening.

CONCLUSION

The 7-year implant survival and the functional outcomes for THA performed with the study device are excellent and were in line with those documented for comparable contemporary uncemented fully HA-coated stems. Longer term follow-up of this consecutive series needs to be performed.

Relationship between body mass index changes and blood pressure changes from childhood to adulthood in a general Chinese population: a 26 year cohort follow-up study

The aim of this study was to estimate the relationship between body mass index (BMI) and blood pressure (BP) in a Chinese population with 26 year follow-up. The study included 4211 schoolchildren aged 6-17 years in Hanzhong, Shaanxi Province, China. Body weight, height, waist circumference, and BP were measured in 1987, 1989, 1992, 1995 and 2013. Cox proportional hazards model were fitted to examine the effect of BMI on BP. At the 26 year follow-up, 6.93% of male and 3.43% of female subjects had high SBP, and 12.8% of male and 4.56% of female had high DBP. The average age of subjects with high SBP was 40.3 years in males and 41.4 years in females; while the average age with high DBP was 38.1 years in males and 38.9 years in females. Obese subjects were 2.96 times and 2.88 times more likely to have high SBP and high DBP than normal weight counterparts, respectively; while overweight subjects were 1.81 times and 2.03 times more likely to have high SBP and high DBP, respectively. These findings underscore the urgent need to prevent increasing body weight. Targeting intervention in adolescence may be a critical method for preventing high BP in later life.