Day 039 - 20 Oct 94 - Page 71


     
     1   Q.   On page 9:  "This work was confirmed by a study in which
     2        male ... rats were exposed to 1 or 2% BHA in a powdered
     3        diet for 104 weeks with animals sacrificed in groups of 10
     4        every 8 weeks during the course of the study.  ...
     5        Hyperplasia of the forestomach was observed in a few
     6        animals of both treatment groups at the first observation
     7        time, 8 weeks after the start of the exposure."
     8
     9        Please drop your eye down to the next paragraph:  "A 104
    10        week exposure of male and female .. rats to 0.5 or 2% BHA
    11        in pellets was also reported."  Again this is Ito -- mostly
    12        Ito up to 1987:  "There were approximately 50 rats per
    13        exposure group.  The mean body weights of both sexes were
    14        reduced in those animals given 2%", and so on and so
    15        forth.  Are you still saying that this is an insufficient
    16        number of animals exposed to a variety of dosages?
    17        A.  Yes, I am, because what matters, I think, amongst other
    18        things, is the numbers of animals at each dose group.
    19        I mean -----
    20
    21   MR. JUSTICE BELL:  Why do you say more than 50?  It appears that
    22        50 is a pretty typical group and there is often less, but
    23        Ito, upon whom you rely quite strongly for some of his
    24        initial findings, seems to think that 50 was sufficient to
    25        try and get some useful indicator.  Without any disrespect
    26        to you, these are people who are spending a lot of their
    27        time carrying out animal experiments, are they not?
    28        A.  Indeed they are.
    29
    30   Q.   And have nothing to gain from doing their work less than
    31        thoroughly?
    32        A.  That, of course, is true.  I cannot put words into
    33        Professor Ito's -----
    34
    35   Q.   What does Professor Ito have to gain from it?
    36        A.  It would be inappropriate for me to put words into
    37        Professor Ito's mouth, but I would be very surprised if he
    38        would not say that he would be delighted to work with
    39        larger groups if he could obtain the funding enabling him
    40        to do so.  50 animals per dose group is the standard.  The
    41        current orthodox protocol for long-term feeding study
    42        involves using 50 animals per gender per dose group.
    43
    44        My response to that is to say, if that is to be the
    45        orthodox experimental approach, and that is supposed to be
    46        the model of the effects on humans and adverse effects
    47        occur, then they should be taken at face value and not
    48        simply disregarded.  If you want to disregard them as
    49        disproportionately high doses but you want a test that is
    50        sufficiently sensitive, not merely to ensure that if the 
    51        compound causes cancer it causes cancer at a rate lower 
    52        than 5 or 10 per cent in the population, but causes cancer, 
    53        if at all, at a very much lower rate, it is only possible
    54        to gain confidence that the rate would be significantly
    55        lower if you have a large enough population of animals that
    56        will give you that sensitivity.  With 50 animals per gender
    57        per dose group you cannot be confident that the real --
    58        I mean, let us suppose you have -----
    59
    60   MR. JUSTICE BELL:  Just pause for a moment because what you are

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