Day 244 - 03 May 96 - Page 23


     
     1   Q.   In the second paragraph on that page 2:
     2
     3        "It is thus my view that any exposure to OP residues is
     4        undesirable in that damage may be caused, the damage rather
     5        than the toxins being cumulative."
     6
     7        Can you explain what you mean?
     8        A.  Yes.  This is the difference, and it is a subtle but
     9        important difference between the two main groups of
    10        pesticides, the organochlorines.  They build up in fat and
    11        as long as they sit there in relatively stable fat they are
    12        doing nothing to the body system.   In fact, the body is
    13        shunting them out on to a siding where they are actually
    14        not doing very much, at least short-term.
    15
    16        OPs work differently in that they are absorbed by -- their
    17        structure is such that they of a predilection to the
    18        nervous system, and it is also important to note the
    19        metabolites.  It is not just the question that the chemical
    20        itself is converted in the digestion system into a
    21        secondary product, i.e. the metabolite.  That has the
    22        capability to do harm.
    23
    24        The point is that we are not dealing with a poison, say,
    25        like cyanide, or a fraction doses is relatively easily
    26        neutralised by the body.  We are dealing with something
    27        which is a molecule which at any level will do damage, will
    28        actually physically damage the nervous system.  Obviously
    29        very small doses of the chemical will do very small amounts
    30        of damage.
    31
    32        Now, the trouble is that the one system in the human body
    33        which does not repair itself is the nervous system.
    34        Therefore, continued exposure to very, very, very small
    35        levels of OPs gives you very, very, very small amounts of
    36        damage to the nervous system.  Over the years, that damage
    37        accumulates.  As I have said here, it is about -- you have
    38        in the human body about 30 per cent redundancy.  That
    39        varies individual to individual.  You can find different
    40        routes -- the nervous system can find different routes,
    41        ways around blockages; but it comes to a point where the
    42        damage builds to a level where first you start suffering a
    43        wide variety of ill-health effects and then, latterly, you
    44        start exhibiting detectable, recognisable signs of that
    45        damage.
    46
    47        Thereby, you can say, that in a multi-faceted exposure,
    48        where you are receiving it environmentally, from food, from
    49        fairly innocuous or apparently innocuous home insecticide
    50        products, that cumulative dose from those variety of 
    51        sources can do harm.  Therefore, it is extremely desirable 
    52        to reduce one's exposure overall, in which context it is 
    53        undesirable to expose yourself to a dietary source of
    54        pesticide residues.
    55
    56   MR. JUSTICE BELL:  Do you put yourself forward as an expert so
    57        far as the central nervous system is concerned?
    58        A.  No, I rely on other work and I can cite it and bring it
    59        forward.  I rely very much on the work of Dr. Jamal from
    60        Edinburgh -- no, sorry Glasgow  -- who has done an enormous

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