Day 022 - 12 Sep 94 - Page 33
1 MR. JUSTICE BELL: Yes.
3 MR. MORRIS: If it does come up again today, we have the
4 reference. (To the witness): Dr. Arnott, if we can have
5 a look at the types of studies in evidence, not
6 necessarily specific ones, but just the types of studies
7 that provide evidence and their strength and weaknesses.
8 You have talked a lot about what you feel are the
9 weaknesses of the population studies which are the country
10 by country type of studies. Could you play devil's
11 advocate? You are obviously not one that strongly
12 supports that, relying on those, but what would be the
13 advantages of the population studies in terms of
14 identifying dietary factors and cancer, for example?
15 A. Right. I would think that what population studies can
16 do is to point you into a certain direction to look at
17 whether certain factors may be responsible for the
18 causation of cancer. For example, if you see marked
19 differences between different countries, you could look
20 more closely at the populations of those countries, trying
21 to look at, trying to identify factors which may be
22 different between the populations in the hope that that
23 might give you a lead as to possibly causation of cancer.
25 Q. That is something that would not be so easy to do in other
26 types of studies because of the extremes, often extremes,
27 of populations differences?
28 A. Sorry, which other studies?
30 Q. What are the advantages of those kinds of studies,
31 population studies, as compared to other types of studies
32 whether cohort or animal testing, whatever?
33 A. I think population studies, looking at what happens in
34 population, can only give you broad brush strokes of what
35 is going on. They then point you towards more detailed
36 research that needs to be carried out, trying to identify
37 what the differences that you may see, you know, possibly
38 are due to.
40 MR. JUSTICE BELL: They are, presumably, more readily available
41 in the first instance in that you might discover that
42 Scotland or Finland have high rates of heart disease just
43 from readily available figures as to numbers of people who
44 are dying of heart disease? So that gets you -----
45 A. That is true.
47 Q. Is that what you are saying?
48 A. That is what I am saying. The difficulty with them is
49 the populations, where one often sees low incidences of
50 disease such as heart disease, are often the countries
51 where the actual information available is of poor
52 quality. So, for example, if you go to Indonesia or
53 Thailand, one of the first things one has to try to do is
54 identify whether the differences are actually due to
55 informational problems in developed countries. You have
56 good backup systems, good information systems; in
57 under-developed countries, you do not necessarily have
58 those. That is one of the first things you need to do,
59 but what you say is exactly right; one often has readily
60 available, relatively crude data on which one can then