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Oral Session 1 – Radiation

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O1.1 INDOOR RADIATION POLLUTION: AETIOLOGICAL INVESTIGATION

N. Chaiear1, N. Saejiw2, S. Dithisawatwet3, P. Polpila3, S. Wichianwetch4, K. Paratago1, K. Chuntum1.1Department of Community Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; 2Institute of Allied Health Science and Public Health, Walailak University, Nakon Sri Thammarat, Thailand; 3Disease Prevention and Control Office, Region 6, Khon Kaen, Thailand; 4Bureau of Waste Management and Hazardous Substances, Bangkok, Thailand

Introduction: The indoor working environment of offices is frequently assumed to be free of toxins. However, individuals working in offices and other indoor areas frequently complain of acute discomfort. Symptoms involve skin, eye, nose, and throat irritation, headache, fatigue, and breathing problems.

Objective: To investigate reasons why 21 persons suffered dermopathy, conjunctivitis, and rhinitis after staying in a closed room for 3 hours.

Methods: This was a multidisciplinary case study including interviews, building and ventilation inspections, and measurement of potential toxin concentrations.

Results: Most of the affected individuals complained of skin irritation and redness of eyes. Only one complained of runny nose. The medical records showed that most individuals presented with epidemic keratoconjunctivitis. The room was found to have two, ceiling mounted, 40 W UV germicidal lamps (G40T10, Sankyo Denki Co., Japan), that were accidentally switched on while the room was occupied. By a process of investigative elimination, we deduced that the reported symptoms were caused by accidental exposure to ultraviolet C radiation.

Conclusion: Safeguards are needed to ensure germicidal lamps are not accidentally switched on while a room is occupied; alternatively, they should be removed if no longer in use.

O1.2 EXTERNAL RADIATION EXPOSURE AND CANCER MORTALITY AMONG FRENCH CEA AND COGEMA WORKERS

M. Telle-Lamberton1, E. Samson1, S. Caër2, D. Bergot1, D. Bard1, F. Bermann3, J. M. Gélas2, J. M. Giraud3, C. Hill4, P. Hubert1, M. O. Néron3, B. Quesne2, M. Tirmarche1.1Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-roses, France; 2COGEMA, Coordination Médicale, Velizy-Villacoublay, France; 3Commissariat à l’Energie Atomique, DRHRS, Paris, France; 4Institut Gustave Roussy, Département Biostatistiques et Epidémiologie, Villejuif, France

Introduction: A total of 29 204 workers employed for more than 1 year at the Commissariat à l’Energie Atomique (CEA) and COGEMA nuclear companies between 1946 and 1994 was followed up for an average of 17.8 years. It consists of workers who were either entirely monitored for ionising radiation at CEA nuclear sites or entirely monitored at COGEMA nuclear sites.

Methods: Individual x ray and gamma ray exposure was reconstructed. A flag indicating potential exposure to other type of radiation (neutrons and internal contamination) was provided. Two subcohorts were defined: 14 796 workers potentially exposed only to x rays and gamma rays, and 14 408 potentially exposed to all types of ionising radiation.

Results: As a first stage, analyses were performed for the whole population. Standardised mortality ratios (SMR) were computed with reference to the French national population. Dose–effect relationship was analysed for 25 different types of cancer plus several groupings through trend tests and Poisson regressions, linear modelling, and log linear modelling. The cohort had a mean x ray and gamma ray exposure of 8.3 mSv (16.9 mSv after exclusion of non-exposed people). A total of 1842 deaths occurred between 1968 and 1994. A strong healthy worker effect was observed (all cause of death SMR 0.59; 95% confidence interval (CI) 0.57 to 0.61). Excesses of skin melanoma (SMR 1.98; 95% CI 1.24 to 3.01; n = 16) and multiple myeloma were observed (SMR 1.62; 95% CI 0.98 to 2.53; n = 14). Dose–effect relationships were observed for leukaemia (except chronic lymphoid leukaemia), and mouth and pharynx cancers. Further analyses will be made with the distinction of the two groups: those only exposed to x and gamma radiation and those potentially exposed to other types of radiation. This will allow a better assessment of the part of excess cancer risk due to external radiation exposure.

Conclusions: Results on smoking related, mouth, and pharynx cancers may be due to confounding factors.

O1.3 CANCER AND OTHER MORTALITY IN THE US IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY, A LARGE NUCLEAR RESEARCH FACILITY

M. K. Schubauer-Berigan, G. V. Macievic, D. F. Utterback, C-YTseng.Health-Related Energy Research Branch, Division of Surveillance, Hazard Evaluations and Field Studies, National Institute for Occupational Safety and Health, Cincinnati, OH, USA

Introduction: The Idaho National Engineering and Environmental Laboratory (INEEL) is a large US Department of Energy (DOE) facility that has conducted a wide variety of activities, including engineering and basic scientific research, nuclear reactor design and testing, nuclear material chemical processing, and the construction, servicing, and demolition of large scale facilities. An epidemiological study was initiated to evaluate hazards associated with ionising radiation and other exposures at INEEL.

Methods: This cohort study comprises 63 561 civilian workers ever employed by the DOE, its contractors, or the US Navy at the INEEL from 1949 to 1991. Mortality and causes of death were ascertained during 1999. Exposures were estimated to external ionising radiation, and internal exposure was also classified, using site records. Subcohorts identified include construction, asbestos, reactor, chemical, and security workers, and painters and drivers. Standardised mortality ratios (SMRs) and standardised rate ratios (SRRs) were calculated based on regional populations and on internal comparisons, respectively. Poisson regression was used to evaluate associations between external radiation and cancers.

Results: INEEL workers exhibited slightly lower mortality rates than the general regional population (overall SMR 0.96; 95% confidence interval (CI) 0.94 to 0.97; 10 788 deaths), but cancer rates were elevated (SMR 1.07; 95% CI 1.03 to 1.11; 2873 deaths). Radiation monitored workers showed lower mortality than non-monitored workers for most causes of death. Levels of non-Hodgkin’s lymphoma (NHL) were higher, particularly among painters and female construction workers. Asbestosis and mesothelioma death rates were higher among construction (particularly asbestos) workers. Negative dose–response was observed for emphysema and lung cancer, suggesting confounding by smoking, but positive associations were detected for leukemia, NHL, brain, bone, and female breast cancer.

Conclusions: Overall cancer mortality in the INEEL cohort is somewhat higher than expected, but for most cancer types is unlikely to be related to ionising radiation, with the exception of the cancers noted above.

O1.4 URINARY 6-HYDROXY MELATONIN SULPHATE EXCRETION IN WORKERS EXPOSED TO VARIOUS LEVELS OF ELF MAGNETIC FIELDS IN DIFFERENT OCCUPATIONS

F. Gobba1,2, L. Roccatto1,2.1Cattedra di Medicina del Lavoro; 2Dottorato di Ricerca in Sanità Pubblica; Facoltà di Medicina e Chirurgia, Università di Modena e Reggio Emilia, Modena, Italy

Introduction: The hormone melatonin has oncostatic, immunological, and antioxidant properties. Suppression of its production induced by occupational exposure to extremely low frequency magnetic fields (ELF-MF) may represent a biologically plausible mechanism for some effects observed in workers, such as a decrease in immune response or an increase in cancer risk. However, data on the effect of ELF-MF on melatonin production in humans are inconsistent, and further studies are needed.

Methods: We studied 62 workers (28 men and 34 women) engaged in 17 different jobs. Occupational ELF-MF exposure was evaluated throughout three complete work shifts using personal dosimeters. MF levels were sampled every 10 seconds, resulting in more than 8600 measures for each worker. The time weighted average (TWA) exposure was calculated. Melatonin production was evaluated by dosing the main urinary metabolite 6-hydroximelatonin sulphate (6-OHMS). A radioimmunoassay method was applied. Samples of urine were collected on Friday mornings; another sample was collected on the following Monday, to evaluate the possibility of a short term effect of MF on melatonin.

Results: According to the personal TWA values, subjects were divided into two groups: lower exposure (LE; n = 34; MF level ⩽0.2 μT), and higher exposure (HE; n = 28; MF level >0.2 μT). In Friday samples, mean (SD) values of 6-OHMS were respectively 33.3 (14.2) v 40.3 (14.8) ng/mL in LE and HE; not significantly different. In the Monday urine samples, the 6-OHMS values were also not significantly different between LE and HE (32.2 (11.4) v 40.3 (14.8)). The mean ratio between 6-OHMS values in Monday versus Friday samples was 1.1 (0.6) in HE v 1.1 (0.4) in LE: the difference is not significant, not supporting the possibility of an effect of MF on melatonin excretion.

Conclusions: The results of this study do not provide any support to the hypothesis that occupational exposure to ELF-MF can affect melatonin production in workers.

O1.5 COSMIC RADIATION AND CATARACTS IN AIRLINE PILOTS

V. Rafnsson1, E. Olafsdottir2, J. Hrafnkelsson3, G. De Angelis4,5, H. Sasaki6, A. Arnarson2, F. Jonasson2.1Department of Preventive Medicine, University of Iceland, Reykjavik, Iceland; 2Department of Ophthalmology, National-University Hospital, Iceland; 3Department of Oncology, National-University Hospital, Iceland; 4NASA Langley Research Center, Hampton VA, USA; 5Old Dominion University, Norfolk VA, USA; 6Department of Ophthalmology, Kanazawa Medical University, Uchinada, Japan

Introduction: Nuclear cataracts have been associated with ionising radiation exposure in previous studies. Today’s aviation involves exposure to ionising radiation of cosmic origin.

Objective: To investigate whether employment as a commercial airline pilot and the resulting exposure to cosmic radiation were associated with lens opacification.

Methods: Cases of opacification of the ocular lens were found in surveys among pilots and a random sample of the population of Reykjavik. Altogether 445 male subjects underwent a detailed eye examination and answered a questionnaire. Information from the airline company on the 79 pilots’ employment time, annual hours flown per aircraft type, the timetables, and the flight profiles made calculation of individual cumulated radiation dose (mSv) possible using CARI-6 software. Lens opacification was classified and graded according to the World Health Organization simplified cataracts grading system using a slit lamp.

Results: The odds ratio (OR) from logistic regression of nuclear cataracts risk among cases and controls was 3.02 (95% confidence interval (CI) 1.44 to 6.35) for pilots compared with non-pilots, adjusted for age, and smoking and sunbathing habits. The OR of cortical cataracts, central optic zone involvement, and posterior subcapsular cataracts risk among cases and controls was lower than unity, and was not significant for pilots as compared with non-pilots in logistic regression analyses adjusted for these same factors. OR for nuclear cataracts associated with cumulative radiation dose to 40 years of age, adjusted for age, and smoking and sunbathing habits, was 1.06 (95% CI 1.02 to 1.10).

Conclusions: The association between the cosmic radiation exposure of pilots and the risk of nuclear cataracts, adjusted for age, and smoking and sunbathing habits, indicates that cosmic radiation may be a causative factor in nuclear cataracts among commercial airline pilots. This may have implications on cancer risk among aircrews and frequent flyers.

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