# [ RadSafe ] Abstract: Age-at-exposure effects on risk estimates fornon-cancer mortality in the Japanese atomic bomb survivors

Dukelow, James S Jr jim.dukelow at pnl.gov
Fri Dec 9 17:26:18 CST 2005

```
I thank John Jacobus for providing a link to this interesting paper.

I have a few comments following a first pass through the Zhang et al.
paper.

This appears to be an example of the old adage that if you torture a
data set long enough it will tell you what you want to hear.  Perhaps
national policy should be that we torture neither prisoners/detainees
nor data sets.

Table 1 of the paper gives numbers of subjects and numbers of non-cancer
death for various dose ranges.  I have added a calculation of the death
rate per 1000 subjects for each dose range

<0.005 Sv   37458 subjects   12660 deaths   337.98 deaths per 1000
0.005 to 0.1 Sv  31648 deaths   10650 deaths   336.51 deaths per 1000
0.1 to 0.2 Sv   5732 subjects   1975 deaths   344.56 deaths per 1000
0.2 to 0.5 Sv   6332 subjects   2226 deaths   351.55 deaths per 1000
0.5 to 1 Sv    3983 subjects   1292 deaths    324.38 deaths per 1000
1 to 2 Sv     927 subjects    274 deaths     295.58 deaths per 1000
2 to 4 Sv      228 subjects    56 deaths     245.61 deaths per 1000

Totals        86308 subjects    29133 deaths    337.55 deaths per 1000

A Chi-square test (df = 6) of the hypothesis that excess relative risk
per Sv (ERR) = 0 for the overall data set is rejected the two-tailed 2%
level, but the reason for rejection is that ERR = 0 over-predicts deaths
in the 0.5 Sv to 4 Sv groups.  Chi-square tests of hypotheses with ERR >
0 would be rejected at even higher levels (that is smaller values of the
tail probabilities alpha).  The hypothesis that ERR has a small negative
value would be accepted, but I haven't had a chance yet to calculate the
range of such ERR values.

Looking at the rest of the paper, most values of ERR calculated for the
dozens (hundreds?) of confidence intervals reports have confidence
intervals that include negative values of ERR.  A few of the calculated
ERRs are positive with positive confidence intervals.  Several ERRs are
negative, but all have confidence intervals including ERR = 0.

The authors appear to be using standard methods of epidemiology, which
is another story.  No corrections appear to have been made for multiple
tests of hypothesis.

The authors manage to extract a scary abstract from this trash.

Best regards.

Jim Dukelow
Pacific Northwest National Laboratory
Richland, WA
jim.dukelow at pnl.gov

These comments are mine and have not been reviewed and/or approved by my
management or by the U.S. Department of Energy.

-----Original Message-----
Behalf Of John Jacobus
Sent: Friday, December 09, 2005 7:08 AM
Subject: [ RadSafe ] Abstract: Age-at-exposure effects on risk estimates
fornon-cancer mortality in the Japanese atomic bomb survivors

Age-at-exposure effects on risk estimates for non-cancer mortality in
the Japanese atomic bomb survivors
Wei Zhang, Colin R Muirhead and Nezahat Hunter
2005 J. Radiol. Prot. 25 393-404

Abstract:

Full text PDF:
pdf

Statistically significant increases in non-cancer disease mortality
with radiation dose have been observed among survivors of the atomic
bombings of Hiroshima and Nagasaki. The increasing trends arise
particularly for diseases of the circulatory, digestive, and respiratory
systems. Rates for survivors exposed to a dose of 1 Sv are elevated by
about 10%, a smaller relative increase than that for cancer. The
aetiology of this increased risk is not yet understood. Neither animal
nor human studies have found clear evidence for excess non-cancer
mortality at the lower range of doses received by A-bomb survivors. In
this paper, we examine the age and time patterns of excess risks in the
A-bomb survivors. The results suggest that the excess relative risk of
non-cancer disease mortality might be highest for exposure at ages 30-49
years, and that those exposed at ages 0-29 years might have a very low
excess relative risk compared with those exposed at older ages. The
differences in excess relative risk for different age-at-exposure groups
imply that the dose response relationships for non-cancer disease
mortality need to be modelled with adjustment for age-at-exposure.

+++++++++++++++++++
"Efforts and courage are not enough without purpose and direction."
"John F. Kennedy, U.S. President and former Naval Officer

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com

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