Day 022 - 12 Sep 94 - Page 33

     1   MR. JUSTICE BELL:  Yes.
     3   MR. MORRIS:  If it does come up again today, we have the
     4        reference.  (To the witness):  Dr. Arnott, if we can have
     5        a look at the types of studies in evidence, not
     6        necessarily specific ones, but just the types of studies
     7        that provide evidence and their strength and weaknesses.
     8        You have talked a lot about what you feel are the
     9        weaknesses of the population studies which are the country
    10        by country type of studies.  Could you play devil's
    11        advocate?  You are obviously not one that strongly
    12        supports that, relying on those, but what would be the
    13        advantages of the population studies in terms of
    14        identifying dietary factors and cancer, for example?
    15        A.  Right.  I would think that what population studies can
    16        do is to point you into a certain direction to look at
    17        whether certain factors may be responsible for the
    18        causation of cancer.  For example, if you see marked
    19        differences between different countries, you could look
    20        more closely at the populations of those countries, trying
    21        to look at, trying to identify factors which may be
    22        different between the populations in the hope that that
    23        might give you a lead as to possibly causation of cancer.
    25   Q.   That is something that would not be so easy to do in other
    26        types of studies because of the extremes, often extremes,
    27        of populations differences?
    28        A.  Sorry, which other studies?
    30   Q.   What are the advantages of those kinds of studies,
    31        population studies, as compared to other types of studies
    32        whether cohort or animal testing, whatever?
    33        A.  I think population studies, looking at what happens in
    34        population, can only give you broad brush strokes of what
    35        is going on.  They then point you towards more detailed
    36        research that needs to be carried out, trying to identify
    37        what the differences that you may see, you know, possibly
    38        are due to.
    40   MR. JUSTICE BELL:  They are, presumably, more readily available
    41        in the first instance in that you might discover that
    42        Scotland or Finland have high rates of heart disease just
    43        from readily available figures as to numbers of people who
    44        are dying of heart disease?  So that gets you -----
    45        A.  That is true.
    47   Q.   Is that what you are saying?
    48        A.  That is what I am saying.  The difficulty with them is
    49        the populations, where one often sees low incidences of
    50        disease such as heart disease, are often the countries 
    51        where the actual information available is of poor 
    52        quality.  So, for example, if you go to Indonesia or 
    53        Thailand, one of the first things one has to try to do is
    54        identify whether the differences are actually due to
    55        informational problems in developed countries.  You have
    56        good backup systems, good information systems; in
    57        under-developed countries, you do not necessarily have
    58        those.  That is one of the first things you need to do,
    59        but what you say is exactly right; one often has readily
    60        available, relatively crude data on which one can then

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