MEETING BETWEEN AUSTRALIAN AND FRENCH SCIENTISTS

MAY 7-9, 1973 Â·

AT THE AUSTRALIAN ACADEMY OE SCIENCEÂ·,' CANBERRA

REPORT OF THE .AUSTRALIAN SCIENTISTS

Present .

Australian Side '

Sir Rutherford Robertson Professor S.T. Butler '

Dr D. Metcalf Professor M.J.D. White Dr O.H.B'. Priestley jpresent for two sessions  to discuss meteorological questions)

French Side

M. le Professeur A. Gauvenet Dr D. Mechali '

M. J.M; .  Lavie M. A'.F. Chaus sard Ã¢ÂÂ

SECTION A . . . .

This section is identical in the two reports.

1. Dose commitments .

There was general agreement that the technical methods

used by the Australian authorities for measuring quantities of

radiation fall-out are satisfactory and are in accordance with

international practice.  A large degree of agreement was reached

regarding the levels of dose commitment in Australia due to past

French tests. The estima'tes of those dose commitments in millirads

are as follows (for strontium-90 and caesium-137, the low figures

are preferred by the French scientists according to their method

of estimation; the Australian scientists’  estimates are the

higher figures): .

. . . / 2

- 2 -

Thyroid

Element

Thyroid  (young children) (older

children  & adults)

Blood  forming  .  ..cells..

Bone cells

Whole  Body

iodine-151 97 9 0 0 0

short lived 1.5 1.5 1.5 1.5 1.5

strontium-90 0 0 4.0-6.2 5.6-8.5 0

caesium-137 2.0-3.0 2.0-3.0 2.0-3.0 2 .0-3.0 2.0-3.0  (external)  caesium-137 0.9-1.3 0.9-1.3 . 0.9-1.3 0 .9-1.3 0.9-1.3  (internal)  carbon-14 0.2 0.2 0.2 0.3 0.2 .

TOTAL (in  round figures) 102-103 14-15 9-12 10-15 5-6 .

The estimates of the dose commitments due ' to all tests

are as follows (the figures were provided for the meeting by an

Australian government scientist; the values for the French test;

are the higher values from the preceding table):

Element

Thyroid (young children)

Thyroid  (older  children  & adults)

Blood  forming cells

Bone cells

Whole body

French tests 103 15 12 15 . 6

Tests by other nations 74 54 83 96 52

TOTAL for all tests 177 ‘ 69 95 111 58

B'oth delegations agree with the method which has heen

used to obtain these figures.

2. Biological Effects

There was general agreement between both groups that for

certain dose levels, radiation is known to cause damage in humans.

. . . / 3

However, there may be a threshold below which lower levels of .

radiation have no effect, the action on human beings of low

doses and very low doses such as result from the tests never

having been observed. Current work, for example on the phenomenon

of repair by living cells of damage they have suffered at high

doses of radiation, suggests that low doses may not cause cancer

or genetic defects at a rate proportional to dose.  Nevertheless

the international authorities have prudently accepted the hypothesis

of direct proportionality in order to establish accepted dose

limits. Certain additional factors may operate to reduce

significantly the risks below those predicted from a simple

estimation based on proportionality. These include the lesser

effects of certain types of radiation, radiation received at low

dose rates, or over extended rather than brief time periods.

- 3 -

However, there may be a threshold below which lower levels of

radiation have no effect, the action on human beings of low

doses and very low doses such as result from the tests never

having been observed. Current work, for example on the phenomenon

of repair by living cells of damage they have suffered at high

doses of radiation, suggests that low doses may not cause cancer

or genetic defects at a rate proportional to dose. Nevertheless

the international authorities have prudently accepted the hypothesis

of direct proportionality in order to establish accepted dose

limits. Certain additional factors may operate to reduce

significantly the risks below those predicted from a simple '

estimation based on proportionality. These include the lesser

effects of certain types of radiation, radiation received at. low

dose rates, or over extended rather than brief time periods.

s

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SECTION B

The following part of this report is the sole

responsibility of the Australian scientists.

The Australian scientists stressed that, despite the

uncertainties outlined in the above discussion of biological

effects, the only prudent course in attempting to assess the

.  overall risk to the Australian population was to assume direct

proportionality of all biological effects to radiation dosage.

This is the public health position taken by the United Nations

Scientific Committee on the Effects of Atomic Radiation and by

other recognised authorities. The Australian population is

large enough that even very small linear estimates of risk, in

the region of the radiation doses due to the French tests,

yield finite estimates of deaths due to cancer and genetic

abnormalities. The Australian scientists believe that it is

necessary to accept such estimates as realistic and not to take

into account notions of a hypothetical threshold dose below

which damage would not occur. Assuming a linear relationship

between dose received and using maximum published figures for

radiation risks, it has been calculated that, as a result of

past French atomic tests, a final total of 26 cases of thyroid

cancer and 14 cases of leukaemia and other cancers could result

in the Australian population. The Australian scientists present

believe that, as a result of the French tests that have already

occurred, there could be approximately one death or serious

disability in Australia from genetic causes during the first

generation and 18 deaths in all subsequent generations;  these

are minimum estimates, and maximum estimates based on present

e  ÃÂ²  e  I 5

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information (see the Report of the Advisory Committee on the

biological effects of ionizing radiation, U.S. National Academy

of Sciences, November 1972) would be approximately 15 times these

figures.

The above figures are based on the dose commitment

estimates from the French tests given in the tables in Section A.

It should be noted that the report of the Academy of Science

Committee estimated the steady radiation effects to Australia

from French tests in the Pacific,  assuming continued testing at

the French site on a pattern similar to that of the past seven

years, and the harm commitments given in the report must be

interpreted in this light. The dose commitments for the seven

years of French testing in the Pacific are included in the report.

Together with the risk factors used in the report, these

commitments permit a direct computation of the harm commitments

to the Australian population from the past tests. -

Ã¢ÂÂ¢  The Australian scientists drew attention to the additional

harmful effects which would accrue to the Australian population as

a result of the improbable event in which the explosion of a

high-powered bomb was combined with quite exceptional

meteorological conditions giving a high fallout over Australia

(Appendix - Academy Report).

Although the levels of radiation due to the French tests

are unlikely to cause a statistically detectable increase in the

frequency of cancer or genetic abnormalities in Australia, it is

emphasised that there should be no unwarranted exposure to radiation.

Further, with the long-lived isotopes produced as the result of

nuclear explosions, the genetic effects on the Australian population,

though small, are cumulative.

