Mortality and cancer registration experience of the Sellafield workers known to have been involved in the 1957 Windscale accident: 50 year follow-up.
This paper studies the mortality and cancer morbidity of the 470 male workers involved in tackling the 1957 Sellafield Windscale fire or its subsequent clean-up. Workers were followed up for 50 years to 2007, extending the follow-up of a previously published cohort study on the Windscale fire by 10 years. The size of the study population is small, but the cohort is of interest because of the involvement of the workers in the accident. Significant excesses of deaths from diseases of the circulatory system (standardised mortality ratio (SMR) = 120, 95% CI = 103-138; 194 deaths) driven by ischaemic heart disease (IHD) (SMR = 133, 95% CI = 112-157, 141 deaths) were found when compared with the population of England and Wales but not when compared with the population of Northwest England (SMR = 105, 95% CI = 90-120 and SMR = 115, 95% CI = 97-136 respectively). When compared with those workers in post at the time of the fire but not directly involved in the fire the mortality rate from IHD among those involved in tackling the fire was raised but not statistically significantly (rate ratio (RR) = 1.11, 95% CI = 0.92-1.33). A RR of 1.11 is consistent with an excess relative risk of 0.65 Sv(-1) as reported in an earlier study of non-cancer mortality in the British Nuclear Fuels plc cohort of which these workers are a small but significant part. There was a statistically significant difference in lung cancer mortality (RR = 2.18, 95% CI = 1.05-4.52) rates between workers who had received higher recorded external doses during the fire and those who had received lower external doses. Comparison of the mortality rates of workers directly involved in the accident with workers in post, but not so involved, showed no significant differences overall. On the basis of the use of a propensity score the average effect of involvement in the Windscale fire on all causes of death was - 2.13% (se = 3.64%, p = 0.56) though this difference is not statistically significant. The average effect of involvement in the Windscale fire was - 5.53% (se = 3.81, p = 0.15) for all cancers mortality and 6.60% (se = 4.03%, p = 0.10) for IHD mortality though neither figure was statistically significant. This analysis of the mortality and cancer morbidity experience of those Sellafield workers involved in the 1957 Windscale fire does not reveal any measurable effect of the fire upon their health. Although this study has low statistical power for detecting small adverse effects, due to the relatively small number of workers, it does provide reassurance that no significant health effects are associated with the 1957 Windscale fire even after 50 years of follow-up.
McGeoghegan
D
D
Westlakes Research Institute, Westlakes Science and Technology Park, Moor Row, Cumbria, UK.
Whaley
S
S
Binks
K
K
Gillies
M
M
Thompson
K
K
McElvenny
D M
DM
D000328:Adult; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000401:mortality*; D009688:Nuclear Reactors / Q000706:statistics & numerical data*; D009784:Occupational Diseases / Q000401:mortality*; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000706:statistics & numerical data; D012042:Registries / Q000706:statistics & numerical data*; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult