Day 256 - 04 Jun 96 - Page 31


     
     1                     Cross-examined by MR. RAMPTON QC
     2
     3   MR. RAMPTON:  Professor Campbell, do you have access there to
     4        your first China study paper, the one that appeared in,
     5        I think it is the American Journal of Clinical Nutrition?
     6
     7   MR. JUSTICE BELL:  If you could put back that bundle and get the
     8        other one down.  It is in H3?
     9        A.  You said H3?
    10
    11   Q.   Yes.  You had it open.  I will find it for you, Professor
    12        Campbell.
    13
    14   MR. RAMPTON:  Before I ask you to look at it, Professor
    15        Campbell, can I ask you some general questions about
    16        epidemiology.
    17
    18        When epidemiologists talk about "risk factors", do they
    19        mean simply factors of diet or lifestyle that have been
    20        identified by one or more studies as possible causative
    21        features elements in generation aetiology of the disease?
    22        Is that what a "risk factor" is?
    23        A.  Yes.
    24
    25   Q.   It is not something that has been identified as a cause
    26        necessarily, is it?
    27        A.  Well, it is really a mixture.  I mean we speak of "risk
    28        factors" in a very generic way, so we have various degrees
    29        of supporting evidence for them, including causality.
    30
    31   Q.   Yes, including causality, and plainly there is a scale --
    32        I am not saying there is a scientific scale, but there is a
    33        common sense scale in magnitude of the risk in the risk
    34        factor?
    35        A.  Yes.
    36
    37   Q.   Thus, for example, smoking cigarettes heavily is way up the
    38        scale when you are talking lung cancer?
    39        A.  Yes.
    40
    41   Q.   As a risk factor?
    42        A.  Right.
    43
    44   Q.   High serum cholesterol is a fair way up the scale when you
    45        are talking about coronary heart disease?
    46        A.  Yes.
    47
    48   Q.   The mere fact that something is identified as a "risk
    49        factor" does not mean one can attach a causal label to it;
    50        does it? 
    51        A.  That is true but causality, well, you know, causality 
    52        certainly enters into the equation and so the risk factors 
    53        become ever more convincing as causality begins to build.
    54
    55   Q.   I entirely accept that, Professor Campbell, perhaps we can
    56        agree, there is no point in studying factors which nobody
    57        thinks could possibly be causal; is there?
    58        A.  Yes, there is.
    59
    60   Q.   In what sense?  To eliminate them?

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