Absence of evidence for threshold departures from linear-quadratic curvature in the Japanese A-bomb cancer incidence and mortality data
by M.P. Little, C.R. Muirhead
International Journal of Low Radiation (IJLR), Vol. 1, No. 2, 2004

Abstract: The recently released data on cancer incidence and mortality in the Japanese A-bomb survivors are analysed using a variety of relative risk models which take account of errors in estimates of dose to assess the dose-response at low doses. If a relative risk model with a threshold (the dose-response being assumed linear above the threshold) is fitted to the solid cancer incidence or mortality data, a threshold of more than about 0.25 Sv is inconsistent with both the incidence and mortality data, whereas this data is consistent with there being no threshold. If a relative risk model with a threshold (the dose-response being assumed linear above the threshold) is fitted to the leukaemia incidence or mortality data, a threshold of more than about 0.4 Sv is statistically inconsistent with the data. In contrast to the solid cancer data, the best estimate for the threshold level in the leukaemia incidence data is statistically significantly different from zero, even when allowance is made for a possible quadratic term in the dose-response, albeit at borderline levels of statistical significance (p = 0.04). However, the best estimate of the threshold is not statistically significantly different from zero in the mortality data (p = 0.16). The statistical significance of the threshold effect for leukaemia incidence is lost if the assumed geometric standard deviation of the random error in the dose estimates is increased from (the central estimate of) 35% to 45%. Given the similarity of the leukaemia mortality and incidence datasets, the reasons for this difference are not entirely clear, but the most likely explanation is the finer disaggregation of dose groups in the publicly available version of the leukaemia mortality data compared with the incidence data.

Online publication date: Mon, 10-May-2004

The full text of this article is only available to individual subscribers or to users at subscribing institutions.

 
Existing subscribers:
Go to Inderscience Online Journals to access the Full Text of this article.

Pay per view:
If you are not a subscriber and you just want to read the full contents of this article, buy online access here.

Complimentary Subscribers, Editors or Members of the Editorial Board of the International Journal of Low Radiation (IJLR):
Login with your Inderscience username and password:

Username:        Password:          Forgotten your password?

Want to subscribe?
A subscription gives you complete access to all articles in the current issue, as well as to all articles in the previous three years (where applicable). See our Orders page to subscribe.

If you still need assistance, please email subs@inderscience.com