Day 038 - 19 Oct 94 - Page 31
1 indicating different sensitivity of different species, my
2 evidence indicates that the official regulatory bodies are
3 not always doing what nominally they say they are going to
4 do; they do not always rely on no effect levels from the
5 most sensitive species when setting the ADI.
6
7 Q. Is it your opinion that is the most relevant result from
8 the most sensitive species?
9 A. Most certainly, yes. That is how I understand the
10 rationale underlying the use of the concept of the ADI.
11
12 Q. You did touch on the carcinogenicity. If a test shows up
13 or finds a non-genotoxic carcinogenicity, or whatever, what
14 is your conclusion for safety implications?
15 A. My most common response to that is to want to know
16 quite a lot more before I make an evaluation, but it seems
17 to me that, without further information, it would be unwise
18 and imprudent to assume that there is a threshold for
19 non-genotoxic carcinogenesis.
20
21 The concept of the ADI, the acceptable daily intake, is
22 quantitative in figure, chisled into the regulations. The
23 assumption underlying that is that there is a threshold and
24 it can be identified. Before I would be happy to endorse
25 an ADI for a known animal carcinogen, I would want to be
26 sure that we understood the mechanism whereby the compound
27 caused cancer in laboratory animals, and we would want to
28 know not just that, say, the metabolism of that compound
29 was different in humans from the laboratory animal, we
30 would need to know how it was metabolised by humans as well
31 as by the laboratory animal and that the roots were
32 significantly different; that that significant difference
33 enabled us to be confident that it would not cause cancer
34 in humans, either at the same site as it did in the
35 animals, or at other sites, and that we knew enough about
36 the metabolic root in humans to know that it was subject to
37 a threshold. Under those circumstances, I might be
38 prepared to countenance or endorse setting an ADI for a
39 non-genotoxic carcinogen; but otherwise not.
40
41 Q. Is it true that if carcinogenicity is shown in results
42 whether it is benign or toxic ----?
43 A. Malignant.
44
45 Q. -- malignant, as far as you are concerned, that is evidence
46 that that compound is not safe?
47 A. I would not quite characterise it like that. I would
48 characterise it as prima facie evidence that it may not be
49 safe and sufficient evidence not to authorise it for
50 general use in the food supply without a considerable
51 amount of further information of the kind I indicated in my
52 previous answer.
53
54 MR. JUSTICE BELL: Unless there is something which is so related
55 that you want to deal with it before one o'clock,
56 I understand that Mr. Cannon may not be required to come
57 back.
58
59 MR. RAMPTON: Not by me.
60
