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March 11, 2000


New Bt toxin has allergen potential?


AgBioView - http://www.agbioworld.org, http://agbioview.listbot.com/

From: Wayne Parrott
Subject: Re: New Bt toxin has allergen potential?


This rumor has been going around for some time. It has been addressed in
Agrevo's web page at

In addition, I said quite a lot about in the Plant TC last year: Here is
what I said in that posting:

I take it you are asking about maize with the cry9C gene in it.

It would probably help to point out that all plants approved for marketing
in the US are a matter of public record.
See http://NBIAP.BIOCHEM.VT.EDU/ for access to all the necessary
information. Specifically, under the section of Crops No Longer Regulated
By USDA, if you click the full record
option, you can find the entire environmental assessment statement filed
to obtain each approval for each gene-crop combination. This description
describes each gene transformed into the plant, and its evaluation.

The USDA has also launched its own web site
(http://www.aphis.usda.gov/biotechnology/) which describes all the safety
assessments in place. Between these two pages, it is possible to obtain
enormous amounts of information. Hence, it is always possible to compare
the claims antiGMO groups make with reality.

Note that Bt is also regulated by the EPA. Here is the current status of
Cry9C, based on its initial Environmental Assessment statement

" Under the Federal Food, Drug, and Cosmetic Act (FFDCA) (21 U.S.C. 301
et seq.), pesticides added to (or contained in) raw agricultural
commodities generally are considered to be unsafe unless a tolerance or
exemption from tolerance has been established. Residue tolerances for
pesticides are established by EPA under the FFDCA; and the FDA enforces
the tolerances set by the EPA. On September 19, 1997, the EPA announced
receipt of the initial filing of a pesticide petition (PP 7F4826),
submitted by PGS, proposing an exemption from the requirement of a
tolerance for residues of plant-pesticides B. thuringiensis subsp.
tolworthi Cry9C and the genetic material necessary for the production of
this protein in or on all raw agricultural commodities (62 FR 49224). The
EPA has not announced its decision on this petition, but it has however
granted a temporary exemption from the requirement of a tolerance for
residues of this insecticide in corn for feed use only; as well as in
meat, poultry, milk, or eggs resulting from animals fed such feed. This
regulation is effective April 10, 1998 (63 FR 17687)."

So the way I read it, initial approval for this corn is contingent on its
not being used as food for humans. Further action
(http://www.epa.gov/fedrgstr/EPA-PEST/1998/May/Day-22/p13604.htm) was
taken by the EPA a month later:

"This regulation eliminates the need to establish a maximum permissible
level for residues of this plant- pesticide in or on corn used for feed;
as well as in meat, poultry, milk, or eggs resulting from animals fed such
feed. EFFECTIVE DATE: This regulation is effective May 22, 1998.
Objections and requests for hearings must be received by EPA on or before
July 21, 1998."

This means that

"This exemption from the requirement of a tolerance will permit the
marketing of feed corn containing the plant-pesticide; as well as meat,
poultry, milk, or eggs resulting from animals fed such feed. The data
submitted in the petition and all other relevant material have been

The EPA finding continues as follows (same web address as before):

"B. Mammalian Toxicological Profile

Consistent with section 408(b)(2)(D) of FFDCA, EPA has reviewed the
available scientific data and other relevant information in support of
this action and considered its validity, completeness and reliability and
the relationship of this information to human risk. EPA has also
considered available information concerning the variability of the
sensitivities of major identifiable subgroups of consumers, including
infants and children. Additionally, section 408(b)(2)(D)(v) requires that,
when considering whether to establish, modify, or revoke a tolerance, the
Agency consider ``available information'' concerning the cumulative
effects of a particular pesticide's residues and ``other substances that
have a common mechanism of toxicity.''

A search for
amino acid homology did not reveal any significant homology with known
toxins or allergens.

EPA's conclusion
that no mammalian toxicity is anticipated from dietary exposure to the
genetic material necessary for the production of the Cry9C protein."

" A comparison of the amino acid sequence of the Cry9C protein with
those found in the PIR, Swiss-Prot and HIV AA data bases did not reveal
any significant homology with known toxins or allergens. The in vitro
digestibility study showed the Cry9C protein to be stable to pepsin at
pH 2.0. The Cry9C protein was shown to be stable to heat at 90 deg. C
for 10 minutes and the Cry9C protein in corn is the trypsin resistant
core and is therefore stable to tryptic digest. The best available
information to date would indicate that edible products derived from
animals such as meat, milk

[[Page 28260]]

and eggs, intended for human consumption, have not been shown to be
altered in their allergenicity due to changes in the feed stock
utilized. This information would include no transfer of allergenic
factors from cattle fed soybeans to the derived meat or milk eaten by
individuals with food sensitivity to soybeans."

And many, many more pages.

As usual, I welcome anyone else who wishes to comment.


3111 Plant Sciences
Dept. of Crop and Soil Sciences
University of Georgia
Phone: 706-542-0926
FAX: 706-542-0914