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cross-pollination,andcontaminationingrainelevators(CDC2001;FIFRA2001).TheU.S.corn
supply has been monitored for the presence of the StarLink Bt proteins since 2001. No positive
samples have been found since 2004, showing that, most probably, it was possible to withdraw
thisGMcropwithoutleavingtracesintheenvironmentonceithadbeenusedintheield(North
AmericanMillers'Association2008).
Anadditionalconcernhasrecentlybeenraisedbythealterationofendogenousgeneexpression,
whichcanbeanalternativemethodofproducingusefulphenotypes,especiallyregardingsecond-
generationGMplants,includingcropsinwhichthenutrientcompositionoravailabilityhasbeen
changedtoaddtothenutritionalvalueofthefood/feed(Harlander2002;ILSI2004;Rotthueset
al.2008).Forexample,ribonucleicacid(RNA)-associatedmechanismscanbeusedtoswitchoff
genes,whiletheup-regulationofspeciictranscriptionfactorscanbeusedtoenhanceexpression
andtherebymodifyaplant'sgrowthorresponsetostress.Sinceneitherofthesetwomechanisms
necessarily depends on the expression of a new heterologous protein(s), it is reasonable to ask if
thesafetyassessmentparadigmdevelopedforandappliedtotransgenicplantsthatexpressnovel
proteinsisappropriateforgeneticallyengineeredplants,inwhichgeneexpressionhasbeenaltered.
Inarecentpaperthatexaminesthesuitabilityofthecurrentlyusedcomparativesafetyparadigm
tocropsinwhichgeneexpressionhasbeenaltered,theauthorsconcludethatthesafetyassessment
paradigm used toassurethesafetyof geneticallyengineeredcropsappears tobe morethan suf-
icientlyrobustforapplicationtogene-modulatedcrops(Parrotetal.2010).
It is certain that nowadays, especially in Europe, GM crops undergo rigorous safety assess-
ment before being allowed to enter the market. One aspect of GM foods that has drawn much
publicattentionbecauseitcoulddirectlyaffectpublichealthistheassessmentoftheirpotential
allergenicity.Allergyisanabnormalimmunereactiontonaturallyoccurringproteinsubstances,
whicharethencalledallergens.Protectingpeoplewithfoodallergiesagainstaccidentalexposure
to allergens has become an important focus for food manufacturers and regulators responsible
forallfoodsafety.Asigniicantfocusofthefoodindustryistokeepfoodproductsthatarenot
intendedtocontainamajorallergen(e.g.,peanut,milk,eggs,orwheat)frombeingcontaminated
with one of the major allergens. Likewise, the primary focus of the safety assessment for GM
crops,asdeinedbytheCodexAlimentariusCommissionin2003,istopreventthetransferofa
geneencodingamajorallergenicprotein(fromanysource)intoafoodcropthatdidnotpreviously
containthatprotein.ProducersofGMcropsandregulatoryauthoritiesfocusonpreventingavoid-
ableincreasesintheriskofallergyinproducingandacceptingnewGMcrops.Itshould,however,
berecognizedthattheabsoluteavoidanceofallrisksisnotachievable.Thus,theassessmentthat
has been developed focuses on avoiding risks that are predictable and likely to cause common
allergicreactions.
Whiletraditionallydevelopedfoodsarenotgenerallytestedforallergenicity,protocolsfortests
forGMfoodshavebeenevaluatedbytheFAOandWHO,andtheallerginicityassessmentofnewly
expressedproteinsisanimportantcomponentinthesafetyevaluationofGMplants(digestibility,
homology,andmammaliantestsareallperformedaspartofallerginicityassessment).Theexis-
tenceofmultipledocumentswithdivergingrecommendationscomingfromdifferentorganizations
hasresultedinconfusionand,sometimes,arbitraryinclusionoftestsuponrequestfromregulatory
authorities.Insomecases,regulatorscontinuedtobasetheirjudgmentonnonvalidated(e.g.,ani-
malmodels)orevenrejected(short-peptidematches)tests.Inparticular,regardinganimalmodels
thatseemedtobequitepromisingwhenirstincludedinthesafetyevaluationofGMplants,itis
recognizedthatnocurrentanimalmodelispredictiveofallergenicityinhumansalthoughtheyare
certainlyusefulformechanisticstudies.Todate,thereisnodocumentedproofthatanyapproved,
commerciallygrownGMcrophascausedallergicreactionsduetoatransgenicallyintroducedaller-
genicproteinorthatthegenerationofaGMcrophascausedabiologicallysigniicantincreasein
theendogenousallergenicityofacrop,despiteextensivebiosafetytestsinseveralcountries,includ-
ingtheU.S.(Goodmanetal.2008).
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