Day 039 - 20 Oct 94 - Page 76


     
     1        conducted".
     2
     3   Q.   "No new studies"?
     4        A.  "No new studies", only the ones that were already
     5        available.  Now, the data show that, yes, indeed, only at
     6        two per cent over that period do you generate the full
     7        tumours, the carcinomas, but at lower doses you get the
     8        induction of hyperplasia which is the precancerous lesion.
     9
    10   Q.   It gives you the percentages of diets at which that
    11        happens, does it not?
    12        A.  It does deeds in those species, but you have to be
    13        careful with interpreting this.  It looks as though it is
    14        saying there were no changes at all at the .1 per cent dose
    15        level.  But that is not strictly correct.  Typically in
    16        these documents what they fail to do is emphasise the
    17        limited sensitivity of these experiments, and what they
    18        should -- I mean, the way in which these results, I think,
    19        should more properly and more scientifically be reported is
    20        that, well, first something about the level of statistical
    21        confidence that one could have in the conclusion, given the
    22        sample that were used on the conclusion that .1 per cent
    23        did not produce lesions.  I suspect if they had done that
    24        it would be clear that while no effect, no statistically
    25        significant effect, occurred, the groups were so small that
    26        one could not have substantial confidence that that was a
    27        genuine negative rather than merely an artefact of the
    28        small, sample size.
    29
    30        Now, they say:  "After re-evaluating the data in pigs, it
    31        was concluded that the evidence is ... questionable".  What
    32        I find when I read these documents is that every parts of
    33        the evidence is questionable, but the committees
    34        selectively choose to question in detail some evidence but
    35        not others.  Just to say "it is questionable" seems to me
    36        to be a rhetorical device and not a systematic, scientific
    37        observation.
    38
    39        Then they say again a couple of sentences down:
    40        "Considering the absence of any significant effects in the
    41        two dog studies, it was concluded that further
    42        investigations in animals without forestomachs are not
    43        required".
    44
    45        Now, that is a judgment about what they deem sufficient,
    46        but there is no reason to think that the dog is a better
    47        model of the human, it provides a better model of the human
    48        digestive tract than a rat does.  What happens is compounds
    49        get tested -- here is a typical example -- in a wide
    50        variety of species.  There are no a priori grounds for 
    51        thinking in advance of the conduct of any study that any 
    52        particular species is a better or worse model than any 
    53        other.
    54
    55   Q.   May I suggest a explanation which might appeal to a less
    56        suspicious mind, Dr. Millstone?  It is this, that it had
    57        been observed for some considerable time that the
    58        forestomachs of rats were susceptible or vulnerable to the
    59        formation of hyperplasia and carcinomas at certain
    60        dosages.  By comparing that phenomenon with the

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