Mortality of workers at the Sellafield plant of British Nuclear Fuels.

The mortality of all 14,327 people who were known to have been employed at the Sellafield plant of British Nuclear Fuels at any time between the opening of the site in 1947 and 31 December 1975 was studied up to the end of 1983. The vital state of 96% of the workers was traced satisfactorily and 2277 were found to have died, 572 (25%) from cancer. On average the workers suffered a mortality from all causes that was 2% less than that of the general population of England and Wales and 9% less than that of the population of Cumberland (the area in which the plant is sited). Their mortality from cancers of all kinds was 5% less than that of England and Wales and 3% less than that of Cumberland. In the five years after their first employment Sellafield workers had an overall mortality that was 70% of that of England and Wales, probably due to healthier members of the population being selected for employment. Raised death rates from cancers of several specific sites were found, but only for those of ill defined and secondary sites was the excess statistically significant (30 observed, 19.7 expected). For cancers of the liver and gall bladder there was a significant deficit of deaths (four observed, 10.5 expected). Workers in areas of the plant where radiation exposure was likely were issued with dosimeters to measure their external exposure to ionising radiations. Personal dose records were maintained for workers who entered such areas other than infrequently. Workers with personal dose records ("radiation" workers) had lower death rates from all causes combined than other workers but the death rates from cancer in the two groups were similar. Compared with the general population radiation workers had statistically significant deficits of liver and gall bladder cancer, lung cancer, and Hodgkin''s disease. There were excesses of deaths from myeloma (seven observed, 4.2 expected) and prostatic cancer (19 observed, 15.8 expected) but these were not significant and there was no evidence of an excess of leukaemia (10 deaths observed, 12.2 expected) or cancer of the pancreas (15 observed, 17.8 expected). Non-radiation workers had a significant deficit of leukaemia (one death observed, 5.1 expected) and a significant excess of cancers of ill defined and secondary sites (13 deaths observed, 5.8 expected). For no type of cancer was the ratio of observed to expected deaths significantly different between radiation and non-radiation workers.(ABSTRACT TRUNCATED AT 400 WORDS)     

FISH chromosome analysis of plutonium workers from the Sellafield nuclear facility

Chromosome analysis using a single-color FISH technique to paint three pairs of chromosomes was undertaken on a group of 46 retired plutonium workers with assessed bone marrow doses >60 mSv, 34 of whom were categorized as having robust dosimetry and 12 for whom internal doses were considered less reliable. Comparisons were made with a group of 34 workers with negligible radiation exposure and a group of 34 workers with similar recorded external gamma-ray doses but negligible internal dose. The simple translocation frequency of 17.65 +/- 1.96 x 10(-3) per genome equivalent for the 34 plutonium workers with robust dosimetry was significantly increased in comparison with that of 10.06 +/- 1.16 x 10(-3) per genome equivalent for the unirradiated control group (P = <0.001) and that of 13.55 +/- 1.43 x 10(-3) per genome equivalent for the group with similar external gamma-ray exposure (P = 0.012). Thus, although in vitro studies have indicated that the majority of alpha-particle-irradiated cells suffer complex non-transmissible chromosome damage, in vivo a significant proportion survive with simple exchanges that can be passed on to descendant cells. In contrast, the three groups demonstrated no significant differences in stable complex aberrations. No evidence of an increase in dicentrics or unstable complex aberrations associated with plutonium exposure was observed, and it can therefore be assumed that there is little, if any, ongoing irradiation of mature lymphocytes. The translocation frequency of 12.08 +/- 1.92 x 10(-3) per genome equivalent for the group of 12 plutonium workers with less reliable internal dosimetry could adequately be accounted for by age and external dose and indicates that the internal bone marrow doses are likely to have been overestimated. Cytogenetic analysis can therefore make a valuable contribution to the validation of internal doses from plutonium deposition.     

Somatic cell mutations at the glycophorin a locus in erythrocytes of radiation workers from the Sellafield nuclear facility

The glycophorin A (GPA) somatic mutation assay for N0 and NN mutant erythrocytes was performed on 245 current and 48 retired workers who had been occupationally exposed to radiation at the British Nuclear Fuels plc facility at Sellafield. A positive association with increasing age was found for current workers for both N0 and NN frequencies of 0.14 +/- 0.05 x 10(-6) (P = 0.012) and 0.25 +/- 0.07 x 10(-6) (P = 0.0003) per year, respectively. No association with age was found for the retired workers. In a comparison of ever-smokers with never-smokers, no difference was observed for N0 frequencies for current workers, but a significantly higher frequency was found for ever-smokers in the retired group (P = 0.001). NN mutant frequencies were slightly higher in ever-smokers than in never-smokers for both current and retired workers, but in neither case was the increase significant. In age-adjusted analyses for N0 mutant frequencies, a slight positive radiation dose response was found for current workers (1.6 +/- 3.8 x 10(-6) per Sv), for retired workers (2.9 +/- 2.5 x 10(-6) per Sv), and in the combined analysis (2.6 +/- 2.2 x 10(-6) per Sv), but in no case did this reach significance. Similar analyses for NN mutant frequencies revealed a positive dose response for current workers (4.7 +/- 4.6 x 10(-6) per Sv) and a negative response for retired workers (-2.4 +/- 3.6 x 10(-6) per Sv) that was maintained in the combined analysis (-1.4 +/- 2.8 x 10(-6) per Sv), but none of these slopes was significantly different from zero. The results suggest that the GPA mutation assay is insufficiently sensitive to be used as a biological marker of low-dose chronic exposure and provide further evidence that, in contrast to high acute radiation exposure, protracted exposure is much less effective at inducing somatic mutations in vivo.     

FISH chromosome aberration analysis on retired radiation workers from the Sellafield nuclear facility

Chromosome analysis using fluorescence in situ hybridization was undertaken on 294 retired workers from the British Nuclear Fuels plc facility at Sellafield, 95 with external occupational exposure <50 mSv, 108 with 50-499 mSv, and 91 with >500 mSv. In univariate analyses, external dose (P <10-s) and age (P = 0.0075) were significantly associated with translocation frequency, but no effect was found for smoking status. In a multivariate analysis with age and external dose as continuous variables, the slopes were 0.017 +/- 0.0075 x 10(-2) translocations per cell per year for age (P = 0.024) and 1.11+/- 0.190 x 10(-2) translocations per cell per sievert for external dose (P < 10(-5)). The dose response for translocation induction for occupational workers is similar to the linear component of in vitro dose-response curves, thus supporting the use of translocation frequency for retrospective biological dosimetry in situations of chronic low-dose exposure occurring over many years. The dose response obtained in this study is lower than the linear component of the dose response for stable chromosome aberrations obtained for the Japanese atomic bomb survivors. Thus, if chromosome aberration levels are indicative of cancer risk, this would suggest that low-dose risks derived from the Japanese atomic bomb survivor data will overestimate the risks associated with the occupational exposure encountered by the men in this study.     

Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

OBJECTIVE--To examine whether the observed excess of childhood leukaemia and lymphoma near the Sellafield nuclear plant is associated with established risk factors or with factors related to the plant. DESIGN--A case-control study. SETTING--West Cumbria health district. SUBJECTS--52 Cases of leukaemia, 22 of non-Hodgkin''s lymphoma, and 23 of Hodgkin''s disease occurring in people born in the area and diagnosed there in 1950-85 under the age of 25 and 1001 controls matched for sex and date of birth taken from the same birth registers as the cases. MAIN OUTCOME MEASURES--Antenatal abdominal x ray examinations, viral infections, habit factors, proximity to and employment characteristics of parents at Sellafield. RESULTS--Expected associations with prenatal exposure to x rays were found, but little information was available on viral illnesses. Relative risks for leukaemia and non-Hodgkin''s lymphoma were higher in children born near Sellafield and in children of fathers employed at the plant, particularly those with high radiation dose recordings before their child''s conception. For example, the relative risks compared with area controls were 0.17 (95% confidence interval 0.05 to 0.53) for being born further than 5 km from Sellafield 2.44 (1.04 to 5.71) for children of fathers employed at Sellafield at their conception, and 6.42 (1.57 to 26.3) for children of fathers receiving a total preconceptual ionising radiation dose of 100 mSv or more. Other factors, including exposure to x rays, maternal age, employment elsewhere, eating seafood, and playing on the beach did not explain these relationships. Focusing on Seascale, where the excess incidence has predominantly been reported, showed for the four out of five cases of leukaemia and one case of non-Hodgkin''s lymphoma whose fathers were employed at Sellafield and for whom dose information was obtained that the fathers of each case had higher radiation doses before their child''s conception than all their matched control fathers; the father of the other Seascale case (non-Hodgkin''s lymphoma) was not employed at the plant. These results seem to explain statistically the geographical association. For Hodgkin''s disease neither geographical nor employment associations with Sellafield were found. CONCLUSIONS--The raised incidence of leukaemia, particularly, and non-Hodgkin''s lymphoma among children near Sellafield was associated with paternal employment and recorded external dose of whole body penetrating radiation during work at the plant before conception. The association can explain statistically the observed geographical excess. This result suggests an effect of ionising radiation on fathers that may be leukaemogenic in their offspring, though other, less likely, explanations are possible. There are important potential implications for radiobiology and for protection of radiation workers and their children.     

Methods and basic data of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

OBJECTIVE--To examine whether the observed excess of childhood leukaemia and lymphoma near the Sellafield nuclear plant is associated with established risk factors or with factors related to the plant. DESIGN--A case-control study. SETTING--West Cumbria health district. SUBJECTS--52 Cases of leukaemia, 22 of non-Hodgkin''s lymphoma, and 23 of Hodgkin''s disease occurring in people born in the area and diagnosed there in 1950-85 under the age of 25 and 1001 controls matched for sex and date of birth taken from the same birth registers as the cases. MAIN OUTCOME MEASURES--Antenatal abdominal x ray examinations, viral infections, habit factors, proximity to and employment characteristics of parents at Sellafield. RESULTS--Ascertainment of cases through multiple sources was as complete as possible, and the diagnosis was established for nearly all cases from hospital records and by independent pathological review when suitable material (60% (58) of cases) was available. Identification and tracing of the parents of cases and controls enabled questionnaires to be forwarded to 730 (66%), and 467 (64%) of the questionnaires were returned completed. Obstetric records were located for 481 (44%) of the relevant births, more frequently in recent years. Linkage of study subjects to the Sellafield workforce file enabled dates of employment and records on external doses of whole body ionising radiation to be obtained. Concordance of information from duplicate sources (when available) was reasonably high with no indications of bias. CONCLUSION--Overall the collected data were sufficiently reliable for detailed analysis and careful interpretation.     

Geographical distribution of preconceptional radiation doses to fathers employed at the Sellafield nuclear installation,West Cumbria.

OBJECTIVE--To examine whether the geographical distribution of births associated with preconceptional exposure of fathers to radiation at the Sellafield nuclear installation is consistent with the suggestion that this exposure explains the excess of childhood lymphoid malignancy in the adjacent village of Seascale. DESIGN--Retrospective birth cohort study. SETTING--Cumbria, West Cumbria health district, and Seascale civil parish. SUBJECTS--The 10,363 children born in Cumbria during 1950-89 to fathers employed at Sellafield. MAIN OUTCOME MEASURES--The doses of external whole body ionising radiation received by fathers at Sellafield in the total time and in the six months before conception of their children; the proportions of the collective doses associated with Seascale and the rest of West Cumbria. RESULTS--9256 children were born to fathers who had been exposed to radiation before the child''s conception. Of these, 7318 had fathers who were exposed in the six months before conception. Overall 7% (38 person-Sv) of the collective total preconceptional dose and 7% (3 person-Sv) of the collective dose for the six months before conception were associated with children born in Seascale. Of all the children whose fathers worked at Sellafield, 842 (8%) were born in Seascale. The mean individual doses before conception were consistently lower in Seascale than in the rest of West Cumbria. CONCLUSIONS--The distribution of the paternal preconceptional radiation dose is statistically incompatible with this exposure providing a causal explanation for the cluster of childhood leukaemias in Seascale.     

Possible genetic damage in the Czech nuclear power plant workers

The aim of our study was to identify occupational risk of irradiation exposure in the Czech nuclear power plant workers. We analyzed levels of chromosomal aberrations, a well-known biomarker of early biological effects and a predictor of cancer risk. We applied the conventional method of cytogenetic analysis and fluorescence in situ hybridization (FISH, whole chromosome painting for chromosomes 1 and 4, combined with a pancentromeric probe) to three groups: 123 subjects in the Temelin nuclear power plant (2 years in use), 114 subjects in the Dukovany nuclear power plant (20 years in use), and 53 matched controls from Ceske Budejovice. Nuclear power plant workers were divided into two groups: subjects with admittance into the monitored zone, and others. Following factors were also analyzed: GSTM1, GSTT1, GSTP1, XPD, XRCC1, hOGG1, p53, MTHFR, and MS gene polymorphisms, levels of vitamins A, C, E, and folate in plasma, and level of cotinine in urine. Long-term exposure to ionizing radiation in the monitored zone was 0.47+/-1.50 mSv (miliSievert) in the Temelin nuclear power plant and 5.74+/-9.57 mSv in the Dukovany nuclear power plant. Using the conventional cytogenetic analysis, we observed 1.90+/-0.95 and 1.82+/-1.19% AB.C. (percent of aberrant cells) in the Temelin nuclear power plant, and 2.39+/-1.01 and 2.33+/-1.04% AB.C. in the Dukovany nuclear power plant, for monitored zone workers and others, respectively. In the control group, we found 2.25+/-0.82% AB.C. Genomic frequency of translocations F(G)/100 measured by FISH was 1.89+/-1.40 and 2.01+/-1.68 in the Temelin nuclear power plant, and 2.48+/-1.93 and 2.14+/-1.62 in the Dukovany nuclear power plant for monitored zone workers and others, respectively. In the control group, F(G)/100 was 1.83+/-1.19. Following factors were identified as potential confounders by the conventional cytogenetic analysis: XPD-6, by the FISH: age, GSTP1 and p53Bst genotypes, long-term use of medication, alcohol consumption, and smoking. No association between the dose of irradiation and the level of chromosomal aberrations in any nuclear power plant was detected either by the conventional cytogenetic analysis or by FISH.     

A cytogenetic study of nuclear power plant workers using the micronucleus-centromere assay.

A cytogenetic study was performed in 215 nuclear power plant workers occupationally exposed to radiation using the micronucleus-centromere assay for peripheral blood lymphocytes. As control population served administrative staff with yearly doses below 1 mSv. The increase of the micronucleus frequency with age, observed in the non-smoking control population, is mainly due to an enhanced number of centromere-positive micronuclei, pointing to an increased chromosome loss. No differences in the number of micronuclei, centromere-positive and centromere-negative micronuclei between smokers and non-smokers are observed. An analysis of the micronucleus data vs. the dose accumulated over the 10 years preceding the venepuncture shows no significant clastogenic or aneuploidogenic effects of the exposure in the studied population which is representative for workers in the nuclear industry at present. According to the linear fits to our data an increase of the micronucleus frequency pro rata 0.5 per 1000 binucleated cells per year, related to the centromere-negative micronuclei, may be expected for workers with the maximal tolerable dose of 20 mSv/year.     

Characteristics of the cohort of workers at the Mayak nuclear complex.

At Branch No. 1 of the Russian State Research Center "Biophysics Institute", a registry has been created of workers at the "Mayak" Production Association, the first nuclear complex in Russia. This registry includes 18,830 persons hired at Mayak's nuclear reactors and radiochemical and plutonium production plant between 1948 and 1972. Twenty-five percent of these workers are women. As of December 31, 1994, the vital status is known for approximately 90% of the cohort members. A total of 5,118 persons have died. The cause for 97% of total deaths has been ascertained. The cohort members were exposed to both external gamma radiation and internal radiation from incorporated plutonium. The plutonium body burden has been measured in 30% of the cohort members with potential for plutonium exposure. External gamma-ray doses were in the range from tenths of milligrays to about 10 Gy, and plutonium body burdens were up to about 260 kBq. In view of the nature of the Mayak worker cohort, it has the potential to provide reasonably precise, quantitative estimates of the long-term health effects associated with chronic low-dose-rate exposure to external gamma radiation as well as internal radiation from plutonium. However, a number of issues must be addressed before credible risk estimates can be obtained from this cohort. These issues include the development of an appropriate internal comparison group and/or external rates and separating of the effects of internal and external exposures on risk estimates.     

Granulocyte metabolism in workers at a coke-processing plant]

Acid phosphatase activity examinations and nitrotetrazolium blue reduction test after latex stimulation in peripheral blood neutrophils were performed in the group of 32 coking plant workers. Reference group consisted of 150 men not exposed to any toxic substances. Neutrophils of coking plant workers, comparing with the reference group, revealed decreased activity of acid phosphatase and impaired reduction of nitrotetrazolium blue after latex stimulation. The results suggest the possibility of toxic influence of coking plant environment on the lysosomal enzymes and oxygen-dependent metabolism of neutrophils what subsequently may diminish bactericidal powers.     

Cancer in Cumbria and in the vicinity of the Sellafield nuclear installation, 1963-90.

OBJECTIVE--To reappraise the epidemiological findings reported by the Black Advisory Group concerning a possible excess of malignant disease, particularly of childhood acute lymphoid leukaemia and non-Hodgkin lymphomas, in the vicinity of the Sellafield nuclear installation, and to determine whether any excess of malignant disease had occurred among people aged 0-24 years in the area in the years after the Black report--that is, from 1984 to 1990. DESIGN--Calculation of incidence of cancer using data from population based cancer registries and special surveys. SETTING--England and Wales; county of Cumbria; county districts Allerdale and Copeland within Cumbria; Seascale ward within Copeland. SUBJECTS--All residents under the age of 75 years in the above areas, but with particular reference to those aged 0-24 years. MAIN OUTCOME MEASURES--Numbers of cases and incidence particularly of lymphoid leukaemia and non-Hodgkin lymphomas in those aged 0-24 years, but including other cancers and age groups. RESULTS--Previous reports of an increased incidence of cancer, especially of leukaemia, among those aged 0-24 years in Seascale during the period up to and including 1983 are confirmed. During 1984-90 there was an excess of total cancer among those aged 0-24 years. This was based on four cases including two cases of non-Hodgkin lymphoma but none of leukaemia. There was an increased, but nonsignificant, incidence of other cancers, based on two cases (one pinealoma and one Hodgkin''s disease) occurring among those aged 15-24 years during 1984-90. This was not observed in the younger age group or in previous years. For the immediately surrounding area--that is, the county districts of Allerdale and Copeland excluding Seascale and in the remainder of Cumbria--there was no evidence of an increased incidence of cancer among those aged 0-24 years in either period. CONCLUSIONS--During 1963-83 and 1984-90 the incidence of malignant disease, particularly lymphoid leukaemia and non-Hodgkin lymphomas, in young people aged 0-24 in Seascale was higher than would be expected on the basis of either national rates or those for the surrounding areas. Although this increased risk is unlikely to be due to chance, the reasons for it are still unknown.     

Micronucleus frequency is increased in peripheral blood lymphocytes of nuclear power plant workers

Nuclear power plant workers are exposed to ionizing radiation at relatively low doses and for prolonged periods of time. To investigate the extent of genetic damage in these workers, a group of 133 nuclear power plant workers and 39 healthy controls were compared using the cytokinesis-block micronucleus assay. The frequency of micronuclei was significantly increased in peripheral lymphocytes of nuclear power plant workers (20.5 +/- 9.7% compared to 13.7 +/- 5.9%). A significant dose-response relationship was observed between micronucleus (MN) frequency and both the accumulated dose and the duration of employment (P < 0.01 for both variables after adjusting for age, gender and cigarette smoking) with an evident leveling off for exposures over 200 mSv. Accumulated dose and duration of employment were significantly correlated but exerted independent effects on MN frequency. For non-occupational parameters, age was significantly associated with the frequency of micronuclei, while gender was not. Smoking habit showed no overall effect, whereas increased chromosome damage was evident in smokers of more than 20 cigarettes per day. In conclusion, a dose-related association between MN frequency and exposure to ionizing radiation was evident in nuclear power plant workers, encouraging the application of the cytokinesis-block micronucleus assay in biomonitoring studies of human populations with prolonged exposure to ionizing radiation.     

Psychophysiological characteristics of young workers at an aircraft plant

The results of an evaluation of the psychophysiological characteristics of young workers exposed to factors of aircraft production indicate functional stress, inefficiency of work, detraining of the cardiovascular system, limited psychophysiological potential, and dissatisfaction with work in the majority of examined young workers.     

Chromosome aberrations in workers at a storage battery plant in Iraq

The present study deals with the determination of the incidence of chromosome changes in workers at a factory making storage batteries in Baghdad city. Blood samples were collected from 19 workers and 9 employees of the Scientific Research Council as control individuals, and chromosomes prepared from lymphocyte cultures were analyzed by standardized methods. Statistical analysis of the results gave significantly higher frequencies of chromatid and chromosome aberrations, particularly gaps, among the workers. No significant differences were observed in the incidence of chromosome aberrations in cells of smokers and non-smokers in both lead-exposed workers and controls. Therefore the observed increase in these aberrations was found to be associated mainly with exposure to lead oxides during the manufacture of the lead alloy grids and lead smelting.     

Cancer mortality risk among workers at the Mayak nuclear complex

At present, direct data on risk from protracted or fractionated radiation exposure at low dose rates have been limited largely to studies of populations exposed to low cumulative doses with resulting low statistical power. We evaluated the cancer risks associated with protracted exposure to external whole-body gamma radiation at high cumulative doses (the average dose is 0.8 Gy and the highest doses exceed 10 Gy) in Russian nuclear workers. Cancer deaths in a cohort of about 21,500 nuclear workers who began working at the Mayak complex between 1948 and 1972 were ascertained from death certificates and autopsy reports with follow-up through December 1997. Excess relative risk models were used to estimate solid cancer and leukemia risks associated with external gamma-radiation dose with adjustment for effects of plutonium exposures. Both solid cancer and leukemia death rates increased significantly with increasing gamma-ray dose (P < 0.001). Under a linear dose-response model, the excess relative risk for lung, liver and skeletal cancers as a group (668 deaths) adjusted for plutonium exposure is 0.30 per gray (P < 0.001) and 0.08 per gray (P < 0.001) for all other solid cancers (1062 deaths). The solid cancer dose-response functions appear to be nonlinear, with the excess risk estimates at doses of less than 3 Gy being about twice those predicted by the linear model. Plutonium exposure was associated with increased risks both for lung, liver and skeletal cancers (the sites of primary plutonium deposition) and for other solid cancers as a group. A significant dose response, with no indication of plutonium exposure effects, was found for leukemia. Excess risks for leukemia exhibited a significant dependence on the time since the dose was received. For doses received within 3 to 5 years of death the excess relative risk per gray was estimated to be about 7 (P < 0.001), but this risk was only 0.45 (P = 0.02) for doses received 5 to 45 years prior to death. External gamma-ray exposures significantly increased risks of both solid cancers and leukemia in this large cohort of men and women with occupational radiation exposures. Risks at doses of less than 1 Gy may be slightly lower than those seen for doses arising from acute exposures in the atomic bomb survivors. As dose estimates for the Mayak workers are improved, it should be possible to obtain more precise estimates of solid cancer and leukemia risks from protracted external radiation exposure in this cohort.     

Comparison of p53 levels in lymphocytes and in blood plasma of nuclear power plant workers

p53 levels were assessed in lymphocytes and in blood plasma of workers from two Czech nuclear power plants (NPP): 114 subjects working in Temelin and 108 subjects working in Dukovany. Ionizing radiation (IR) exposure data were available for 64 and 59 subjects working in the monitored zones from the NPP in Temelin and Dukovany, respectively. The short-term doses of IR for these subjects were 0.01 and 0.12 mSv, and the long-term doses were 0.46 and 5.68 mSv, in the Temelin and Dukovany NPP, respectively. As a control group, 46 subjects living in České Budějovice, a city nearby the Temelin NPP, were analyzed. The concentration of p53 in lymphocytes was significantly higher in workers from the monitored zone in the Dukovany NPP (median value 6.4 pg/μg protein, P < 0.001) than in workers from the Temelin NPP (3.2 pg/μg) as well as in the control group (3.5 pg/μg). In contrast, plasma levels of p53 were comparable in the control group (median value 116 pg/ml plasma) and workers from the monitored zone of Dukovany NPP (102 pg/ml), but lower in workers from Temelin NPP (5 pg/ml). Other factors affecting p53 levels were studied. Smoking resulted in increased p53 lymphocyte levels. The effect of polymorphisms in metabolic and DNA repair genes on p53 levels was analyzed. The correlation was found between p53 levels in lymphocytes and p53 codon 72 polymorphism in subjects working in NPPs, but not in the control group.

The results of measurement p53 levels in lymphocytes suggest that this biomarker could reflect the short-term as well as long-term effects of low doses IR. Its impact on human health should be further explored.     

Sleep complaints and polysomnographic findings: a study of nuclear power plant shift workers

The literature widely recognizes that shift workers have more health complaints than the general population. The objective of this study was to describe the prevalence of sleep complaints and verify the polysomnographic (PSG) variables of shift workers in two Brazilian nuclear power plants. We carried out a subjective evaluation with a sleep questionnaire. Based on these results, the interviewees that reported sleep-related complaints were referred for polysomnographic evaluation. Of the 327 volunteers initially evaluated by the sleep questionnaire, 113 (35%) reported sleep complaints; they were significantly older, had higher body mass index (BMI), and worked more years on shifts than those without sleep complaints. Of these 113, 90 met criteria for various sleep disorders: 30 (9%) showed obstructive sleep apnea (OSA), 18 (5.5%) showed limb movement, and 42 (13%) evidenced both sleep problems and had a significantly higher proportion of sleep stage 1 and arousals compared with the 23 shift workers that had no indices of sleep problems. The present study found that 90 (27.5%) of the evaluated participants met the PSG criteria of some type of clinical sleep disorder. This high proportion should be investigated for associations with other aspects of work, such as working hours, working schedule, years performing shift work, and access to health services. Due to the strong association between sleep disorders and the incidence of fatigue and sleepiness, the evaluation of the sleep patterns and complaints of shift workers is essential and should be considered to be one of the basic strategies of industry to prevent accidents.