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experience:
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Medical Microbiologist
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summary:
The witness in his capacity as a medical microbiologist provides essentially what is a scientific report on the issues surrounding BSE and the risk posed to humans.
The statement is uncompromising in its stance.
It was therefore known at that time that a risk was present to
humans and that the calculation of this risk was currently impossible.
cv:
Not available for this witness
Full cv:
(not available for this witness)
full statement:
Concerning the Development of Bovine Spongiform Encephalopathy.
It is thought that the presence of pesticides in the tissues of
bovines may be a contributory factor to the outbreak of BSE in the UK.
The worry is that the pesticides (in this case organophosphate
insecticides) may act on the animal tissues to produce a transmissible
spongiform encephalopathy, which may in turn be a risk to human
health.
Proof for this is not available at this point and research into it is
continuing.
Investigation is underway into the medical ethics of whether things
that are not adequately certain to be safe to humans should be
banned. This is particularly important here in that, should BSE (or
the insecticides that may be associated with it), cause a fatal human
disease as a result of eating beef products, probably after the year
2000, the action necessary to prevent it could only have been taken
before there was proof that this would happen, i.e. while there was no
certainty of the safety of the food. I will try to give a better
description of this below.
In medical practice, drugs and actions must be shown with specific
animal and human tests to be either:
- not a risk to humans at all or
- of adequate advantage that this outweighs the risk to humans. While
such evidence is not available the drugs or actions are assumed to be
too great a risk to be acceptable.
The reason for this assumption is that very large numbers, indeed a
large section of the population, receive certain drugs (etc). If a
drug should turn out to be fatal then this would be such an enormous
catastrophe (e.g. thalidomide) as to be unacceptable as a risk. The
same ethics applies to food additives (and, presumably artificial
chemicals present in foods), and they, as a result are treated in the
same way by various foreign governments (e.g. the Food and Drugs
Administration in the United States). In the UK it is not clear how
ethical decisions are made concerning these chemicals in food.
The major problem with BSE is that there is no evidence that BSE will
not infect humans to produce a similarly untreatable, undiagnosable,
fatal disease (indeed we can estimate that there is a 70% chance that
humans could be affected). The ethical question about this is as to
whether such a large part of the population should be put at risk of a
fatal disease before evidence is available that humans are not at
risk. This question is the moral one that was being considered widely
in 1988- 1991 and would not have required MAFF direction.
supplementary statement:
Concerning Bovine Spongiform Encephalopathy and its relevance to
beefburger production.
- BSE became known to the Central Veterinary Laboratory in 1986 and
had not been diagnosed in the world previously. In 1993 there were
over 36,000 cases.
- This type of disease (called a transmissible spongiform
encephalopathy or TSE) is known to be fatal, there is no treatment,
there is no adequate method of diagnosis before death, they are passed
from one animal to another by the eating of infected tissue.
- TSEs have been either found naturally or produced by experiment
in over 48 species. At the time of the first report of BSE a TSE had
been known in the same way in approximately 37 species, many of them
monkeys.
- BSE has now been transmitted to 18 different species and 16 of
them have been by the presence of the agent in food.
- In 1988 there has a Working Party on BSE (known as the Southwood
Cormmittee) organised by the Ministry of Agriculture Fisheries and
Food (MAFF) in the UK.
At this time it was known,that infectivity was found in almost all
tissues of an infected animal with a TSE but in some tissues in
greater quantities than in others. It was also known that there was
an approximately 70% chance that a TSE could be transmitted to any
other particular mammal (i.e. if inoculated in some way into 10
different species a TSE would be expected to infect 7 of them.) It was
also known that infectivity of tissue started early in the incubation
period with peripheral tissues (liver, lymph nodes, spleen etc) and
later, probably at half the incubation period for nervous tissue.
Of the committee's major recommendations those relevant here were that
no bovine brain be put into baby food, that clinically Infected
animals be destroyed, that the feeding of cattle with potentially
infected material be stopped, and that bovine material not be injected
into humans.
The committee decided that bovine brain/ spleen/ thymus/ liver/ gut/
lymphoid tissue/ bone marrow/ lung/ nerves were not a risk to humans
as it decided that infected animals were being adequately destroyed,
and that, as BSE was derived from scrapie in sheep (a reasonable
presumption but without any evidence) and scrapie did not infect
humans, neither would BSE.
These aspects of logic were untenable at that time because:
- Infectivity of tissue appears long before signs of disease in
TSE and so just slaughtering those with illness will permit large
numbers of infected animals to be eaten.
- There is no evidence that BSE was derived from scrapie, and when
a TSE is transmitted from one species to another it also changes the
range of animals it will then infect.
- It was therefore known at that time that a risk was present to
humans and that the calculation of this risk was currently impossible.
Tyrrell would have been told this by any independent (i.e. external to
MAFF employment) advisor.
- In 1989 an announcement was made by MAFF that the Southwood
committee had not recommended adequately safe procedures and banned
the presence of specific offals in humans (and later animal) food.
This was introduced in November 1989 in England and Wales and in
February 1990 in Scotland. Liver, kidneys, lung, bone marrow, nerves,
all known to be infective in animals infected with a TSE were not
included in this list of banned offals.
- In 1990 I published a scientific article calculating the potential
risk to humans and showing it to be high but assuming specific levels
of infectivity in tissue.
- In 1993 I published a more precise scientific article, fully based
on MAFF data and published scientific facts, and using conservative
assumptions, and standard epidemiological and mathematical techniques
to calculate the risk to humans. This assumed that all cattle with
disease were reported by farmers, that all cattle with BSE disease
were diagnosed, and that BSE behaved like any other TSE. This showed
to the risk to be unacceptably high.
- It also included calculations of the number of infected cattle
that would have been eaten. I now know that this figure is about
1,800,000 cattle by the year 2000.
Data were delivered in advance of publication to members of the
Tyrrell Committee (the Spongiform Encephalopathy Advisory Committee).
- The action that McDonald's should, during the period relevant to
this case, have taken concerning the risk from BSE to their customers
is unclear currently as, although scientific data showed human risk to
be ethically unacceptable, the repeated reports by the MAFF that the
risk was 'minimal'.
- I believe that this is their current opinion despite data now
indicating that BSE was not derived from scrapie, the numbers of
infected cattle eaten being very large and that calves claimed earlier
to lack infectivity have now been indicated (retrospectively) to have
been infected (and eaten).
- It would only have been if McDonalds had sought independent
medical advice concerning food safety that they should have received
full warnings concerning BSE and its risk to humans. As far as I am
aware there are very few people working on risks and epidemiology in
the UK outside MAFF/Tyrrell Committee.
- It would only be between the appearance of the disease (1987) and
the release of the Southwood Report (June 1989, although given to
Government several months earlier), that McDonalds could not have
taken action that was indicated by Government and might have sought
external advice.
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status:
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Reading of this statement in Court as evidence was dissallowed by the Judge
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references:
Not applicable/ available
exhibits:
Not applicable/ available
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