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RE: Substantial equivalence - what is it?



Something I'd like to know more about - the trade regulators have used the
concept, and they're busy applying it to genetically manipulated foods -
but we need to have the analytic and the scientific basis sorted out -- so
here are two recent letters

MichaelP 
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From: Robert <Robert@tiamat.sonnet.co.uk>


It appears that in reviewing GM foods for consumption the relevant bodies
look to see if the novel food is "substantially equivalent" to an existing
natural product.

Is there a definition of exactly what "substantially equivalent" means in
terms of a genetically modified organism.

I don't see how such a term can have any scientific meaning unless it
relates to specific properties of the organism which can be measured. The
word "substantially" also implies that there is some way of knowing if
differences in the measured properties are significant or not.

Perhaps somebody could shed some light on this. It would be particularly
interesting if there were examples of foods that passed, failed and were
considered as borderline against this test.

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as part of this resuting discussion see this { I havn't seen the original
"novel foods" thread )

From: Roberto Verzola <rverzola@phil.gn.apc.org>


To: jralphb@easynet.co.uk
Subject: Re: novel foods
X-PH: V4.1@cornell.edu (Cornell Modified)

 >>Without such a scientific study (ie, a controlled experiment), it
 >>seems to me that any assertion that transgenic foods are safe for
 >>human consumption is an untested hypothesis.
 >
 >Actually, feeding trials on foods have problems that those who ask for
them
 >have perhaps not considered. You might like to consider the paper
 >"TOXICOLOGICAL ASSESSMENT OF NOVEL, PARTICULARLY GENETICALLY MODIFIED
 >(GM) FOODS" of the ACNFP below, adopted last year. This seems to me a
 >balanced approach but I'd be grateful for your comments,

Ralph,

I went through the ACNFP document carefully. In brief, it says that unlike
chemical additives and drugs, food testing is very difficult because:
     - foods are complex aggragates of different substances
     - even maximum doses may have minimal effect on test species
     - food under test may be a significant portion of the entire diet
     - excessive doses are difficult to give
     - acute effects are difficult to produce
     - food testing changes the nutrition of test animals
     - complex metabolism is difficult to follow
     - cause/effect may not be observable or may be confusing

Therefore, safety assessment of novel foods is based on the concept of
"substantial equivalence", a concept developed by the OECD in 1991, based
on FAO/WHO consultations in 1990, and expanded by another FAO/WHO
consultation in 1996.

In short, industry claims that transgenic foods are safe are based on the
determination that they are "substantially equivalent" to their natural
counterpart, which means that they are "as safe as", or "no less safer
than" their natural counterpart. Then there is no need for feeding tests,
except in special cases. And this explains why there have been no feeding
tests of transgenic foods on swine, cattle, primates or human subjects;
neither have there been long-term feeding tests on rats or chicken.
Long-term feeding tests are not necessary because the transgenic food is
substantially equivalent to their natural counterpart.

Is this all? Did I miss anything? Would it be correct to say that on this
argument of substantial equivalence stands the various industry claims
that transgenic foods are safe for human consumption?

I hope you can answer my next question, because "substantial" sounds very
inexact and unscientific. Can we establish "substantial equivalence"
through a scientific experiment? Can we measure equivalence through
repeatable experiments?

To pose the question differently: have there been peer-reviewed published
studies which established "substantial equivalence" between say, natural
corn and Bt corn, or natural soya and herbicide-resistant soya?

I have also seen the report of the FAO/WHO consultation in 1996. You are
right, it endorses the concept of safety assessment based on "substantial
equivalence". I would like to ask though: does that report represent the
official WHO stand on transgenic foods, or is it simply an account of the
discussions? I ask this, because the opening speaker made very clear that
the participants to the consultation were invited in their *personal*
capacity and did not represent their organizations. Thus that 1996 report
is, as I understand it, simply an account of the discussions among
researchers in their individual capacities. The meeting, it is true, was
convened by the FAO and WHO, but do the contents of the report represent
the official WHO stand?

(If anybody on this list has direct access to WHO people, I'd be very
interested about this information: in the 1996 report on the consultation
transgenic foods convened by FAO/WHO, does the reported endorsement of
"substantial equivalence" represent the official WHO stand, or it is
simply reporting an endorsement by the participants to the consultation,
who were there in their individual capacity?)

Thank you and regards,


Roberto Verzola

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