Day 038 - 19 Oct 94 - Page 17
1
2 That apart, the question always then is, given that we have
3 some evidence, for example, of adverse effects at
4 relatively high levels of exposure, which is the position
5 we typically find ourselves in, what assumption should we
6 make about the shape of the curve representing the
7 relationship between dose and effect?
8
9 Those who are keen to have a relatively liberal policy
10 regime usually argue that one can reasonably assume that
11 there is a threshold below which no significant adverse
12 effects occur. But there is no biological basis for that
13 assumption. Typically the postulation of a threshold, it
14 seems to me, involves treating the absence of any evidence
15 as if it were substantive evidence of the absence of an
16 effect.
17
18 It is a leap of faith upon which a policy is sometimes
19 grounded but for which there is no scientific evidence. My
20 understanding of the kinds of biochemical processes
21 involved in toxic effects, and they are very wide ranging,
22 imply that while normally the lower the dose the lower the
23 effect, though not quite always, while generally the lower
24 the dose the lower the effect, one cannot assume simply
25 that one can identify or that there is a level to be
26 identified below which all significant effects cease.
27
28 That, of course, complicates the policy making process,
29 but, in practice, my reading of policy making is that it
30 unrealistically and undesirably over-simplifies the
31 position. So, an assumption that there is a threshold and
32 that it can be identified and that you can rely on rodent
33 studies, and other laboratory animal studies, to identify
34 that threshold, that is an assumption which is commonly
35 made, but I do not find convincing.
36
37 Q. Professor Walker explained that the additives that we are
38 discussing in this court case in terms of their safety have
39 been awarded an acceptable daily intake, or ADI, by the
40 European Scientific Committee for Food as well as the Joint
41 Expert Committee of the United Nations, Food and
42 Agriculture Organisation and the World Health
43 Organisation. Why do you say that is not a sufficient
44 guarantee of their safety?
45 A. Well, I have spent a great deal of the last 20 years --
46 perhaps a disproportionate amount of the last 20 years --
47 scrutinizing the judgments of these expert committees, and
48 as much of the evidence on which they are supposedly based
49 as I have been able to obtain. The pattern I have found in
50 their work is one in which, time and again, when the
51 results of animal studies and other studies on bacteria
52 failed to reveal any evidence of adverse effect, that is
53 spontaneously treated as if it was unproblematically
54 reliable and not subject to a critical scrutiny.
55
56 When, on the other hand, they are confronting and
57 evaluating evidence which appears to show adverse effects
58 on the animal cell culture, tissue culture or bacterial
59 culture of the tests, they seem to introduce an elaborate
60 critical apparatus which they do not otherwise use, or
