Opinion on the Expert Affidavit on Safety Issues of Irradiated Food for
School Children sworn by Dr. William Au, with date of Dec. 10, 2002.
Henry Delincée, Institute of
Nutritional Physiology, Federal Research Centre of Nutrition, Karlsruhe,
Germany. (Opinion expressed on
April 02, 2003)
Reading this affidavit of Dr. Au – which only recently came to my
attention – and mentions my own research on 2-alkylcyclobutanones, provokes
the following statement: I have no reason to doubt Dr. Au’s qualifications in
the field of environmental toxicology, but I do doubt his qualifications in the
field of food irradiation.
Regarding myself, I took my Ph.D. 1972 from the Technical University of
Munich, Germany, on the effects of irradiation on enzymes, and since that time I
have been involved in research regarding food irradiation. Thus, I have more
than 30 years of research experience in this field, and I have published more
than 200 scientific articles connected with food irradiation.
As one of the researchers on the topic of toxicity of
2-alkylcyclobutanones (2-ACBs) in irradiated fat-containing food, I want to
emphasize that we did not show that 2-ACBs are mutagenic. This statement by Dr.
Au is simply wrong! In none of the references he quotes (Delincée and Pool-Zobel,
1998; Delincée et al. 1999; Delincée et al., 2002; Burnouf et al., 2002) can
this statement be found. On the contrary, it is explicitly stated in one of the
references (Burnouf et al., 2002) that although genotoxicity of some 2-ACBs has
been demonstrated, no mutagenic activity has been revealed.
I am wondering why Dr. Au has chosen the form of an affidavit to express
his opinion. Perhaps he would like to emphasize the importance of his
statements. But Dr. Au is not sticking to the scientific facts, he is
exaggerating the potential risk by overstating that 2-ACBs are mutagenic.
Obviously he is not telling the truth, thereby committing perjury. His affidavit
is of no value.
Dr. Au is telling us that his opinion is based on a reasonable degree of
scientific certainty. I disagree. He has not consulted the relevant scientific
literature carefully enough. The amount of information on the toxicology of food
irradiation is very large since it has been investigated thoroughly over the
last five decades. To express an opinion with a reasonable degree of scientific
certainty, it is not enough just to pick out a few selected studies, the whole
body of evidence needs to be taken into consideration.
For example, the numerous peer-reviewed reports about mutagenic
activities of irradiated food fed to mammals, are not so "numerous" as
he claims. All the references which Dr. Au mentions in his section 5, have been
discussed thoroughly in the relevant reports of the WHO (WHO 1994, 1999). It is
explicitly explained in the WHO reports why some of these experiments led to
adverse effects. However, the adverse effects could not be reliably attributed
to the irradiation treatment, but could have been due to an inadequate diet of
the laboratory animals, bad experimental design, inadequate evaluation, etc.
In the enormous amount of studies about the wholesomeness of irradiation
on food, a number of experiments with "adverse" effects stand against
a large number of studies with no adverse effects. A single experiment showing a
certain effect needs to be reproducible before it causes concern. Effects have
to be consistently observed in an adequate number of scientific experiments and
need to be statistically significant in order to be evident with a reasonable
degree of certainty. As the WHO Expert Groups convincingly show, this has not
been the case for the studies resulting in "adverse" effects, cited by
As stated by the WHO (WHO, 1994), none of the conflicting results
identified constitute reasonable grounds for rejecting the use of irradiated
food. It should be recognized that scientific consensus does not depend on every
scientist agreeing with certain conclusions, but rather on how the entire body
of scientific evidence is interpreted by the scientific community. The WHO
Expert Groups certainly have more scientific weight than the single opinion of
Dr. Au, who obviously exaggerates his claims.
Why does Dr. Au neglect all those studies which have not yielded
"adverse" effects? Most of those studies which had shown some
"adverse" effects have been repeated under better experimental
conditions without reproducing these "adverse" effects. Therefore,
only the total body of evidence should be used for risk assessment, and the
evaluation should not be biased by the selection of certain studies.
Coming back to our recent studies on 2-ACBs, it is correct that we have
observed toxic, genotoxic and even tumor promoting activity of certain highly
pure 2-ACBs (Burnouf et al., 2002). These experimental data, however, are
inadequate to characterize a possible risk associated with the consumption of
irradiated food. Other food components may influence the reactions of 2-ACBs not
evident from our experiments on purified 2-ACBs. More knowledge is also needed
about the kinetics and metabolism of 2-ACBs in living organisms. It would,
therefore, at present be premature to draw the final conclusion that 2-ACBs are
a health hazard on consumption of irradiated food. It should be recognized, that
an anticipated risk is probably low, since many feeding studies carried out with
irradiated food – thereby containing 2-ACBs – did not show adverse effects
attributable to the irradiation treatment. Nevertheless, in our opinion it is
necessary to carry out further research in order to quantify the potential risk.
To exaggerate this potential risk and to speak of hazardous substances is not
One can only reach the conclusion that Dr. Au is abusing his position as
environmental toxicologist. Unfortunately he is not aware of the problems in the
toxicology of irradiated food, and is even, in one particular case, simply
ignoring the scientific facts.
D., Delincée, H., Hartwig, A., Marchioni, E., Miesch, L., Raul, F., Werner, D.
(2002) Etude toxicologique transfrontalière destinée à évaluer le risque
encouru lors de la consommation d'aliments gras ionisés / Toxikologische
Untersuchung zur Risikobewertung beim Verzehr von bestrahlten fetthaltigen
Lebensmitteln. Eine französisch-deutsche Studie im Grenzraum Oberrhein. Rapport
final / Schlussbericht INTERREG II.Projet / Projekt No. 3.171. (Marchioni, E.,
Delincée, H., Eds.) Berichte der Bundesforschungsanstalt für Ernährung,
Karlsruhe, BFE-R--02-02, pp. 1-198. (also available at the web: http://www.bfa-ernaehrung.de/Bfe-Deutsch/Information/bfeber91.htm
H. and Pool-Zobel, B.L. (1998) Genotoxic properties of 2-dodecylcyclobutanone, a
compound formed on irradiation of food containing fat.
H., Pool-Zobel, B. L., Rechkemmer, G. (1999) Genotoxizität von
2-Dodecylcyclobutanon (Genotoxicity of 2-dodecylcyclobutanone). In:
Lebensmittelbestrahlung - 5. Deutsche Tagung (Food Irradiation –5. German
Conference), Karlsruhe, 11-12 Nov. 1998, (Knörr, M., Ehlermann, D. A. E.,
Delincée, H., Eds.), Berichte der Bundesforschungsanstalt für Ernährung,
Karlsruhe, BFE-R--99-01, pp. 262-269.
H., Soika, C., Horvatovich, P., Rechkemmer, G., Marchioni, E. (2002)
Genotoxicity of 2-alkylcyclobutanones, markers for an irradiation treatment in
fat-containing food - Part I: cyto-and genotoxic potential of
(1994) Safety and nutritional adequacy of
irradiated food. WHO, Geneva.
(1999) High-dose irradiation:
wholesomeness of food irradiated with doses above 10 kGy. Report of a Joint
FAO/IAEA/WHO Study Group, Geneva. Technical Report Series 890.