Day 014 - 20 Jul 94 - Page 15

     
     1
         Q.   Where you take some people who are suffering from a
     2        condition and you take a parallel group who are not?
              A.  Yes.
     3
         Q.   You observe the effects of diet or supposed effects of
     4        diet on those two different groups?
              A.  Yes.
     5
         Q.   Have I got it right?  Experimental studies, am I right,
     6        are those largely performed on animals?
              A.  In general, yes.
     7
         Q.   Are there also what you scientists call invitro studies?
     8        A.  Yes, there could be.
 
     9   Q.   Clinical studies, I suppose that is obvious; that is the
              observation of morbidity in humans, largely speaking, is
    10        it?
              A.  Yes.
    11
         Q.   Tell us first, please -- use them as a broad category for
    12        present purposes -- what sort of conclusions can safely be
              drawn in general from epidemiological results?
    13        A.  Well, what they will usually provide is associations
              between diet or a characteristic of the diet and the
    14        incidence of the disease, but they do not, of course,
              demonstrate that there is any cause and effect.
    15
         Q.   Let me ask you a further question:  As a responsible,
    16        objective, dispassionate scientist -- hypothesize such a
              person if you will -- what more is required before one can
    17        sensibly or responsibly postulate cause and effect?
              A.  Well, ideally, one would need to try and understand
    18        the actual mechanism which would explain in detail what
              the link was between the diet and the changes that occur
    19        within the body and the final disease state.
 
    20   Q.   To that end are experimental studies and clinical studies
              of assistance?
         A.  Again they make a contribution.
 
    22   Q.   If the epidemiological evidence, the experimental and
              clinical evidence, all pointed in the same direction over
    23        a period of time, could one safely say it is probably so;
              there is a cause and effect?
    24        A.  One probably could, but again we must not
              under-estimate the very considerable difficulties there
    25        are before we come to definite conclusions on the links
              between diet and health. 
    26 
         Q.   How would you describe, if I may put it like this, in 
    27        degrees of certainty the conclusion or proposition which
              is often expressed that there is a causal relationship
    28        between tobacco smoking and lung cancer?
              A.  On a scale of one to 10?
    29
         Q.   If you like?
    30        A.  OK, probably nine.