Day 023 - 13 Sep 94 - Page 03

     
     1        down the microscope what the cells look like, what tissues
     2        the cells have come from originally.  There are two main
     3        types which are cigarette smoking related.  One is
     4        squamous cell cancer.  Squames are the cells which line
     5        the surface tissues of the body, and another one is called
     6        oat cell cancer.  But there are other forms of lung cancer
     7        like adenocarcinoma, which is a sort of glandular type of
     8        cancer which is not smoking related.  But if you look at
     9        the squamous cancers and oat cell cancers, it is extremely
    10        rare to find these in non-smokers, or people who have not
    11        been exposed to cigarette smoking.
    12
    13   Q.   Rare but not impossible?
    14        A.  Not impossible, but something like 98 per cent of
    15        squamous and oat cell cancers; you, in fact, never see oat
    16        cell cancer, apart from very rare incidences, in
    17        non-smokers.  About 98 per cent are in smokers or people
    18        who have been exposed to cigarette smoking at some point
    19        or another in their lives.  The correlation is very high
    20        indeed.
    21
    22   Q.   But you did agree yesterday that the links were not
    23        actually proven in terms of cause and effect?
    24        A.  No, except chemicals have been extracted from
    25        cigarettes which, when painted on animals, cause tumours.
    26        They are a similar type of tumour to that which is found
    27        in cigarette smokers.  There is a lot of research gone
    28        into this looking at the extracts from cigarettes, and in
    29        that sense one can positively state that there is this
    30        direct relationship, between an extract from a cigarette
    31        and that chemical actually causing cancer.
    32
    33   Q.   Right.  But you were talking yesterday about unusual --
    34        with animal experiments, they do not exactly reflect how
    35        things would be done in humans.  For example, humans do
    36        not take cigarette tar and paint it on their skin?
    37        A.  No, but on the other hand, when they inhale
    38        cigarettes, the tar is deposited in the lining of the
    39        tubes, the bronchus, the main tubes, the trachea, leading
    40        to the lungs.
    41
    42   Q.   But you were also talking about dosage.  When you paint
    43        tar on the skins that may be in a far higher concentration
    44        than, you know, people would get if they inhale smoke?
    45        A.  That is right, which is why there is such controversy,
    46        for example, about passive smoking, because people say
    47        there is possibly a concentration factor with the
    48        chemicals contained within the cigarette, and whilst some
    49        people believe there is a relationship between passive
    50        smoking and lung cancer, other people would doubt this. 
    51        It is a controversial area. 
    52 
    53   Q.   Is it also true that there have been experiments on
    54        animals where they inhale smoke and they have not got
    55        cancer?
    56        A.  I am sure there have; I actually do not know that
    57        work.
    58
    59   Q.   You are not aware of it?
    60        A.  Most of this work was done many years ago and, you