Reply to Comment on ‘A geographical study of thyroid cancer incidence in north-west England following the Windscale nuclear reactor fire of 1957’

Abstract

Embargo release date:Perhaps of greater importance to interpretation are the patterns of rate ratios found in the study. Thus, the rate ratio for Cumbrian registrations for those born during 1954-1958 (1.12, for those who were youngest at the time of the accident) was less than that for those born during 1929-1933 (1.44, for those in the study who were oldest at the time of the accident), while the ratio was greatest for those born during 1959-1963 (1.49, for those who were not exposed to 131 I from the accident). The equivalent rate ratios for Lancashire registrations were 1.05, 0.61 and 0.91, respectively. These patterns do not suggest that 131 I exposure from the Windscale accident was responsible for the raised rate ratio for Cumbrian registrations during 1974-2012 among those born during 1939-1958, 1.29, the primary finding. Rather, they suggest either problems with thyroid cancer registration data, the influence of major (nonradiation) risk factors for thyroid cancer, or both. We emphasised this in the paper [1]. We are most surprised that Hunter and Haylock believe that the Abstract of our paper implies that these patterns of rate ratios result from exposure to 131 I from the accident, because we believe that the Abstract clearly implies exactly the opposite.As we made plain in the paper [1], the geographical study can be only a preliminary examination of the potential impact upon thyroid cancer risk of 131 I released during the Windscale accident. We are firmly of the opinion that more detailed investigations are required to better understand the unusual nature of the thyroid cancer registration patterns that we reported [1]. The COMARE Seventeenth Report [2] specifically recommends that such investigations should be conducted.