Day 036 - 13 Oct 94 - Page 40


     
     1   MR. RAMPTON:  It is not terribly important.  You were going to
     2        make a comment?
     3        A.  There are a number of items that came to my
     4        attention.  I did not want to forget to provide something
     5        to you, so I was making a note on my own pad, hopefully,
     6        for your benefit.  It is certainly fair to say that no one
     7        line of investigation alone is conclusive.  In addition to
     8        that, regarding his criteria that must be satisfied in
     9        order for fat enhancement of mammary carcinogenesis to be
    10        expressed, it is simply perhaps worth noting his first one
    11        is carcinogens administrated at a time when the animal is
    12        particularly sensitive to mammary induction.  That does
    13        apply to human populations.  We are exposed to carcinogens
    14        quite regularly, although not only at times when we are
    15        exquisitely sensitive to them, but at all times.  I would
    16        certainly argue that there is no time when we are
    17        insensitive to them, at least that I am aware of.
    18
    19        His second one is that animals are maintained on a
    20        purified diet. My truncated comments earlier went to this,
    21        my reference to Dr. Burkitt's writings, that, regrettably,
    22        human beings on what some have described as indeed a
    23        purified diet.  By "purified" one means removing
    24        components that would naturally be in the diet.  Fibre is
    25        one that has gotten the most discussion but, in addition,
    26        one can easily strip a diet of vitamins and important
    27        minerals.  Regrettably, that is exactly what has happened
    28        when one makes a hamburger bun, for example, one will not
    29        find the same -----
    30
    31   MR. JUSTICE BELL:  You made this point before.  What does a
    32        "purified" diet mean so far as the laboratory rats are
    33        concerned?
    34        A.  It is an imprecise term and can be used in different
    35        ways by different experimenters.
    36
    37   Q.   Do you know how Dr. Burkitt was using it?
    38        A.  I take it to mean in this context a diet which is more
    39        restricted than that which would be normal for a rat in a
    40        laboratory; perhaps would not provide the full range of
    41        nutrients in their full amounts which, regrettably, is
    42        exactly analogous to the human situation.  Human beings do
    43        not get ----
    44
    45   Q.   I am not at all sure it is the same.  I appreciate that
    46        you say we have restrict our diet, it is not as wide as it
    47        might be, but that may or may not be the equivalent of a
    48        purified diet in rats.  You may be right, but until we
    49        know what a purified diet means, it is difficult to say,
    50        is it not? 
    51        A.  Yes.  The third point being ad libitum feeding 
    52        necessary which, obviously, is typical of human 
    53        populations.  Again, he is not speaking here of human
    54        populations.  He is speaking of how to do a rat study in a
    55        way he is satisfied with.  I am simply trying to point out
    56        that at least those, the three that I have discussed so
    57        far, do have parallels in the human population.
    58
    59        Finally, it is worth again emphasising, although the point
    60        seems to get lost, that even in the presence of an agent

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