Cancer risks and low-level radiation in U.S. shipyard workers.

The risks for four cancers, leukemia, lymphopoietic cancers (LHC), lung cancer and mesothelioma, were studied in workers from shipyards involved in nuclear powered ship overhauls. The population represented a sample of all workers based on radiation dose at study termination. The final sample included 28,000 workers with > or = 5.0 mSv, 10,462 workers with < 5.0 mSv and 33,353 non-nuclear workers. Nuclear workers had lower mortality rates for leukemia and LHC than US white males but higher rates of lung cancer and a significant five-fold excess of mesothelioma. Dose-dependent analyses of risks in the high exposure group indicated that for each cancer the risk increased at exposures above 10.0 mSv. An internal comparison of workers with 50.0 mSv exposures to workers with exposures of 5.0-9.9 mSv indicated relative risks for leukemia of 2.41 (95% CI: 0.5, 23.8), for LHC, 2.94 (95% CI: 1.0,12.0), for lung cancer, 1.26 (95% CI: 0.9, 1.9) and for mesothelioma, 1.61 (95% CI: 0.4, 9.7) for the higher exposure group. Except for LHC, these risks are not significant. However, the increasing risk with increasing exposure for these cancers, some of which are known to be related to radiation, suggests that low-level protracted exposures to gamma rays may be associated with these cancers. Other agents such as asbestos, which are common to shipyard work, may play a role especially in the risk of mesothelioma. Future follow up of the population would identify bounds on radiation risks for this population for comparison with similar risks estimated from other populations.

Long-term follow-up of the CAD/CAM patient fitted total temporomandibular joint reconstruction system.

PURPOSE: The purpose of this study was the assessment of the long-term safety and effectiveness of the Techmedica (Camarillo, CA) CAD/CAM Total Temporomandibular Joint Reconstruction System (now called the TMJ Concepts Patient Fitted Total Temporomandibular Joint Reconstruction System, Ventura, CA). PATIENTS AND METHODS: A survey was mailed to the available addresses of 170 (79%) of the 215 patients who had been implanted with the Techmedica System devices between 1990 and 1994. Seventy-nine (46%) surveys were returned by the US Postal Service as undeliverable. Three patients (1.4%) were reported as deceased in returns from relatives. Therefore, of the remaining 91 possible responses, 60 (65.9%) were returned. Fifty-eight (58) surveys, considered complete and valid (96.7%), representing 97 (39 bilateral, 19 unilateral) devices with a mean follow-up of 107.4 +/- 15.5 months (range, 60 to 120 months) were analyzed. Subjective data related to pain, mandibular function, diet consistency, and present quality of life were collected using visual analog scales. Objective measures of mandibular interincisal opening and lateral excursions were obtained from direct measurements using the Therabite (Therabite, Philadelphia, PA) measuring scale provided in the survey with instructions as to its use. RESULTS: Analysis of the subjective data at 10 years revealed a 76% reduction in mean pain scores and a 68% increase in mean mandibular function and diet consistency scores (P <.0001). Analysis of objective data revealed a 30% improvement in mandibular range of motion after 10 years (P =.0009). Long-term quality of life improvement scores were statistically related to the number of prior temporomandibular joint operations the patients had undergone. CONCLUSION: These data indicate that the CAD/CAM Patient Fitted Total Temporomandibular Joint Reconstruction System has proved to be a safe and effective long-term management modality in the patient population surveyed for this study.