Day 038 - 19 Oct 94 - Page 29
1 less trivial than, say, eczema. I mean, eczema itself can
2 be very unpleasant, but it is most commonly relatively
3 mild, itching and skin rashes; whereas hyperactivity is a
4 major blight on the lives of the children, their families
5 and their communities.
6
7 MR. MORRIS: Just to deal with some parts of the jigsaw we may
8 have overlooked before we move on to the specific
9 compounds. I might have to jump about here a little bit.
10 Are the results of tests on animals always consistent?
11 A. Let me see if I have understood the question. Do you
12 mean if you test one compound on several different kinds of
13 animals, do you always get the same answer? Is that what
14 you are asking?
15
16 Q. Not particularly, but that could include it. Just in terms
17 of interpretation of results of animal testing -----
18
19 MR. JUSTICE BELL: Tell the witness what the point is you are
20 getting at.
21
22 MR. MORRIS: I think I am referring to, you can test a group of
23 animals and get one result and test the same group and get
24 a different result in exactly the same circumstances. Is
25 that ----
26 A. It is not uncommon that a given compound tested in a
27 given strain of laboratory animals in different
28 laboratories yields different results. There are
29 variations between laboratories, but it does also, from
30 time to time, happen that a compound may be tested in the
31 same strain of animal in the same laboratory on different
32 occasions generating different results.
33
34 Moreover, there is very considerable variability between
35 species, and even between varieties of a particular
36 species; there are quite a few different kinds of rats and
37 different kinds of mice used in toxicological tests. You
38 do not get consistency even within varieties, within the
39 species, within laboratories or between laboratories, which
40 makes the interpretation subsequently of the results of
41 those studies a very, very difficult matter. The science
42 is anything but cut and dried.
43
44 Q. Are particular animal species identified as most relevant
45 for a particular compound, or ----
46 A. I think that is one of the most important questions in
47 toxicology policy to which no adequate answer has yet been
48 provided. Until the mid-80s I was unable to locate within
49 the toxicological literature any systematic attempt to
50 estimate the extrapolative validity of laboratory
51 animals for human beings. There were then a few attempts,
52 I think, starting in about 1983, 1984, which attempted to
53 estimate the extrapolative validity of rat feeding studies
54 of known human carcinogens to the effects on humans; where
55 we know compounds cause cancer in humans. At the time we
56 were aware of, I think it was about 18 compounds or groups
57 of compounds where, for this purpose, tobacco smoke counts
58 as one group or work in the leather tanning industry counts
59 as one pattern of exposure.
60
