McNally Richard J Q, Wakeford Richard, James Peter W, Basta Nermine O, Alston Robert D, Pearce Mark S, Elliott Alex T
Institute of Health and Society, Newcastle University, Sir James Spence Institute, Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK.
J Radiol Prot. 2016 Dec;36(4):934-952. doi: 10.1088/0952-4746/36/4/934. Epub 2016 Nov 28.
The Windscale nuclear reactor fire at Sellafield, United Kingdom, in October 1957 led to an uncontrolled release of iodine-131 (radioactive half-life, 8 d) into the atmosphere. Contamination from the accident was most pronounced in the counties of Cumbria and Lancashire, north-west England. Radioiodine concentrates in the thyroid gland producing an excess risk of thyroid cancer, notably among those exposed as children, which persists into later life. For an initial investigation of thyroid cancer incidence in north-west England, data were obtained on cases of thyroid cancer among people born during 1929-1973 and diagnosed during 1974-2012 while resident in England, together with corresponding populations. Incidence rate ratios (IRRs), with Poisson 95% confidence intervals (CIs), compared thyroid cancer incidence rates in Cumbria and in Lancashire with those in the rest of England. For those aged <20 years in 1958, a statistically significantly increased IRR was found for those diagnosed during 1974-2012 while living in Cumbria (IRR = 1.29; 95% CI 1.09-1.52), but the equivalent IRR for Lancashire was marginally non-significantly decreased (IRR = 0.91; 95% CI 0.80-1.04). This pattern of IRRs was also apparent for earlier births, and the significantly increased IRR in Cumbria extended to individuals born in 1959-1963, who would not have been exposed to iodine-131 from the Windscale accident. Moreover, significant overdispersion was present in the temporal distributions of the IRRs, so that Poisson CIs substantially underestimate statistical uncertainties. Consequently, although further investigations are required to properly understand the unusual patterns of thyroid cancer IRRs in Cumbria and Lancashire, the results of this preliminary study are not consistent with an effect of exposure to iodine-131 from the Windscale accident.
1957年10月，英国塞拉菲尔德的温斯凯尔核反应堆发生火灾，导致碘 - 131（放射性半衰期为8天）不受控制地释放到大气中。事故污染在英格兰西北部的坎布里亚郡和兰开夏郡最为严重。放射性碘会在甲状腺中富集，从而增加患甲状腺癌的风险，尤其是在儿童时期受到辐射的人群中，这种风险会持续到成年后期。为了初步调查英格兰西北部甲状腺癌的发病率，我们获取了1929年至1973年出生、1974年至2012年在英格兰居住期间被诊断为甲状腺癌的病例数据以及相应的人口数据。发病率比（IRR）及其泊松95%置信区间（CI），用于比较坎布里亚郡和兰开夏郡与英格兰其他地区的甲状腺癌发病率。对于1958年年龄小于20岁的人群，1974年至2012年居住在坎布里亚郡期间被诊断出患有甲状腺癌的人群，其IRR在统计学上显著升高（IRR = 1.29；95% CI 1.09 - 1.52），但兰开夏郡的相应IRR略有下降，且无统计学意义（IRR = 0.91；95% CI 0.80 - 1.04）。这种IRR模式在更早出生的人群中也很明显，坎布里亚郡显著升高的IRR延伸到了1959年至1963年出生的人群，这些人不可能因温斯凯尔事故接触到碘 - 131。此外，IRR的时间分布存在显著的过度离散，因此泊松CI大大低估了统计不确定性。因此，尽管需要进一步调查以正确理解坎布里亚郡和兰开夏郡甲状腺癌IRR的异常模式，但这项初步研究的结果与温斯凯尔事故中接触碘 - 131的影响不一致。
