TECHNICAL EXCHANGE MEETING
GR&DC, JU14E 1982
Session 5: Biologicil Research
Wednesday, 9th June
9.00 p.m. - 11.30 a.m.
Co-ordinator: Dr. R.E. Thornton
Leaky Lungs (Mrs. J. Ramsdale)
Smoke Inhalation Studies (J. Bevan)
Mutagenicity (Dr. E.D. Massey)
Passive Smoking (Dr. R.E. Thornton)
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Introduction
The main objective of biological research is to
design cigarettes with
minimum biological activity. Although it is
possible to relate some
tests to diseases which have been associated with
smoking, this is not
always possible. In this case minimum biological
activity, as defined by
the specified test, is considered sufficient in
its own right.
In some cases Governmentsy or other statutory
bodies, have introduced
legislation relating to the testing of chemicals.
This was exemplified
by the case of ZORBONITE, a filter additive
designed to reduce the level
of nitric oxide in smoke. This material had given
favourable results in
most tests but had been shown to possess strong
sensitising activity.
This implied an allergic response in humans and,
on this basis, its
projected use was abandoned.
A number of contract research studies are being
carried out. Satisfactory
progress is being maintained an current projects,
work has started on a
new one ("Leaky' Lungs, discussed later) and
several are being considered,
notably work on examining the role of nicotine in
affecting metabolism.
Work on nitric oxide retention is also being
considered.
In discussion, there was broad agreement on this
programme. It was noted
that one contract study (the enzyme induction
work) complemented AHH work
being carried out in Canada. Further information
was requested on studies
relating to Atherosclerosis (Professor Caro).
Leaky Lungs
Work on leaky lungs originated at Northwick Park
Hospital, N. London,
when the phenomenon of "shock-lung" was being
investigated. This is an
often-fatal condition in which lungs fill with
fluid. It had been found
that smokers had more permeable lungs than
non-smokers, as measured by
transport of a radioactive chelate through the
lung wall. The change was
reversible and thus a quick, simple, non-invasive
test of lung function
presented itself. Correlation with the magnitude
of the change and carbon
monoxide levels in blood had been demonstrated.
This did not necessarily
demonstrate a causal relationship; carbon monoxide
was chosen because of
its simple assay. Further work was now under way
to investigate the
relationship between carbon monoxide delivery and
"leakiness".
In discussion, there was strong support for this
work, the related work
of J. Hogg in Canada being noted. Attempts to
reproduce the effect in
animals were now under way, both at Northwich Park
Hospital and in
Southampton, although it was pointed out that
background noise levels
might be very high. However, the test might have
utility in examining
sidestream smoke.
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Smoke Inhalation Studies
A period of intensive development has resulted in
the introduction of
radically. new protocols for the testing of low
(including ultra-low)
delivery products by rat inhalation. These became
necessary in order to
achieve a significant pathology effect from
relatively low amounts of
smoke components from such cigarettes. Using these
techniques, studies
will be completed on expanded tobacco and on
cigarettes containing 100%
reconstituted tobacco.
Techniques for measuring biological activity in
response to sidestream
smoke have also been developed. The further
development of techniques
for measuring activity of sidestream smoke is
planned, including a full
programme of studies on reduced sidestream
products. Additionally,
further consideration of markers for smoke
deposition is in hand. Markers
being considered included Catechol and Cadmium, as
well as more conven-
tional markers such as nicotine and the ESCNI-
radical.
Discussion indicated considerable interest in the
results which will come
from the use of these newly developed techniques.
The question of
measurement of sidestream smoke activity was
considered to be an industry
rather than an individual company concern. This
matter is under review.
Mutagenicity
The rationale for conducting mutagenicity studies
was firstly put forward
under the evidence for the effect of mutagens on
the incidence of genetic
diseases, using mutagenesis as indicative of
carcinogenesis and as a
reply to the increasing sphere of legislation. The
concepts of structural
(chromosome) and molecular (gene) mutations were
examined and linked to
the requirement of using a battery of mutagenicity
tests to detect agents
acting at these two levels.
The establishment of the Ames test at GR&DC to
detect gene mutations was
described and the following experiments using this
assay discussed:
1. BAT collaborative study (Southampton, Hamburg,
Montreal) for evalua-
ting the mutagenic potency of a series of
cigarette smoke condensates.
A remarkably good agreement between the
laboratories was found.
2. Sidestream smoke from cigarettes smoked under
normal conditions was
of equal potency to mainstream smoke but had a
reduced potency when
smoked under enclosed conditions. These conditions
will be further
investigated and experiments carried out to
investigate products with
reduced sidestream deliveries.
3. Investigation of a Japanese hemin filter
claimed to eliminate mutagens
from cigarette smoke. In a smoking situation the
filter did not
eliminate mutagens, only reduce them by 11%.
4. The specific activity of a plain cigarette was
found to be lower than
that of a ventilated filter cigarette. Further
investigation of Oo
smoking variables that modulate mutagenicity will
be investigated. CO
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Japanese experiments on the link between tobacco
protein content and
reduced mutagenicity were also described and put
forward as an area for
future work. The mutagenicity test battery will
also be completed by a
test to investigate the ability of chemicals to
damage chromosomes.
In discussione considerable interest was expressed
in the areas of work
described for the future. It was generally agreed
that biological work,
including mutagenicity on sidestream, should
proceed at GR&DC since the
expertise is available and it is preferable to
influence the approach and
techniques later required by outside agencies. The
issue of whether this
work should be "pooled" on an industry basis was
raised and unresolved.
The planned tobacco deproteinisation work-was also
endorsed as part of an
approach to produce the maximum opportunity of
producing products that
will have the minimum interaction with biological
systems. These studies
should also be carried out in parallel with
experiments on the influence
of human smoking conditions on mutagenicity and
smoke chemistry in an
attempt to understand the various interactions in
smoke mutagenicity
modulation.
Passive Smoking
Papers subsequent to and including Hireyama
(January 1981) were discussed.
This is an area of substantial debate and
controversy and the deliberate
misquotation of scientific results (e.g. those of
Feyerabend, Higenbottam
and Russell) were discussed.
Clearly, however, this is an area of considerable
importance.
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BATCO document for Province of BritiSh Columbia 8
November 1999