Comparison of Health and Safety Executive and Cumbrian birth cohort studies of riskof leukaemia/non-Hodgkin’s lymphoma in relation to paternal preconceptionalirradiation

Abstract

In 1993, a case-control study by the Health and Safety Executive (HSE) assessed the risk ofleukaemia and non-Hodgkin’s lymphoma (LNHL) among children of fathers employed at theSellafield nuclear installation in relation to paternal preconceptional irradiation (PPI). Itconcluded that the statistical association between risk of LNHL and PPI was confined tochildren born in the village of Seascale, where the dose-response was extremely high andvery significant. In contrast, in 2002, a Cumbrian birth cohort study, investigating largelythe same cases, concluded that this statistical association was not significantly differentamong children born inside and outside Seascale and estimated the dose-response insideSeascale to be much lower. This review makes a detailed comparison of the twostudies, considering their design, data and analyses. The differences between theirfindings are due to: (i) differences in the distribution of offspring-years which aredifferential with respect to dose category and Seascale birth status, (ii) a non-Seascalehigh-dose case included in the Cumbrian but not the HSE study, (iii) differencesbetween analyses using categorical and continuous PPI dose and (iv) the presenceof Seascale controls with PPI over 200 mSv in the Cumbrian but not the HSEstudy.