Re: dose limits for members of the public

Title: Re: dose limits for members of the public

Barbara L. Hamrick responed "There's not really evidence to support that there's harm either." in response to sandyfl@EARTHLINK.NET comment: :"I also don't agree that we can say that there is no harm to a worker when they have received 5 rem for each year of their employment. There is no evidence to support that."

Colleagues, Both are correct. This is why, as scientists, we should push for a double blind human study at a dose level where there is no evidence of harm, such as the background dose in the U.S, mountains, such as i propose in my article: Is radiation an essential trace energy? Physics and Society October 2001

http://www.aps.org/units/fps/oct01/a5oct01.html

I see no chance that the problem can be solved without better data. I expect that the result of the double blind study will support health benefits at low dose rates.

A recent thesis by Rima Habib of 7000 Australian nuclear workers shows lower death rate from all causes and lower cancer mortality similar to that found in the nuclear shipyard worker study and the British radiologist study for radiologists in the period 1955-1979. This does not prove anything but it strengthens the evidence for beneficial effects:

ANSTO Briefing - Lucas Heights Epidemiological Study
7 August 2001

Ms Rima Habib, today presented to the ANSTO workforce the findings of her doctoral thesis recently submitted to the University of New South Wales. This independent study looked at the risk of contracting cancer from workplace exposure to low-level ionising radiation.

After more than six years of analysis of more than 7000 past and present employees' records spanning five decades, the workforce at the Lucas Heights Science and Technology Centre has been found to have lower cancer mortality rates than the general population of New South Wales as a whole. This was part of a research program being carried out in conjunction with the International Agency for Research on Cancer (IARC) in France.

Comprehensive analyses of the data will be made available through forthcoming publications in appropriate scientific journals.

Overall, the results indicate that the Lucas Heights' workforce have had lower all-cause and cancer mortality rates than the general population and that this effect persists, throughout their employment. In particular:

1.    Lucas Heights employees have had mortality rates from all causes some 31% less than the general Australian population.
2.        Lucas Heights employees have had mortality rates from all cancers some 19% less than the general NSW population.
3.      There has been no significant difference between their leukemia rates and those of the general population.

In addition to the comparison with the NSW population the Lucas Heights data were analysed to compare the cancer rates of the radiation workers from the non-radiation workers. This showed that there was no significant difference between the cancer mortality rates for radiation and non-radiation workers for a range of 32 specific cancer types, except for the groups of brain and central nervous system cancers, and kidney. These forms of cancer have not previously been associated with radiation exposure and the results are therefore likely to be due to the small numbers of cancer deaths in these groups.

The data for radiation workers were also analysed by their cumulative occupational exposure to radiation over the period of study, including non-Lucas Heights exposure. The analysis showed that of the 32 cancer types analysed, there were no recorded cancers in 10 of the types. Of the other 22 cancer types, 21 showed no statistically significant trends and one, lung cancer mortality, was borderline significant. However, lung cancer is known to be affected by a number of other factors, such as smoking, but the study was not able to comprehensively analyse for these other confounding factors. Cancer incidence was also analysed in the study.

The Lucas Heights data, which relate to employees from 1957-1998, have now been assembled, checked and transmitted to IARC. They will be incorporated into a large study, which will, for the first time bring together data from 17 countries to estimate the risk of contracting cancer from exposure to radiation in the workplace. The results of this combined analysis are expected in the early part of 2002.

ENDS
I plan to order a copy of the thesis but it will require a month or so to obtain it.

Best wishes, John Cameron

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