Chemistry Reference
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antibioticconcerned,thedistributionofmicroorganismsalreadypossessingresistancegenesinsoil
andwater,aswellastheirpresenceinthedigestivetractsofhumansorothermammals.Therefore,
transformationtechnologiesnotresultinginclinicallyrelevantantibioticresistancemarkergenes
and/orleadingtomarkergeneremovalhavebeenrecentlydevelopedtoconstructGMcrops(high-
lysine maize compositions and event LY038 maize plants, Patent 7157281, issued on 2 January
2007).ItisexpectedthatGMOswithoutmarkergeneswillsimplifysafetyassessments.
12.2.2 health
The three main issues debated in relation to the impact of GM crops on animal and human
healtharegenetransfer,outcrossing,andtendenciestoprovokeallergicreaction(allergenicity).
Gene transfer from GM foods to cells of the body or to bacteria in the gastrointestinal tract
wouldcauseconcernifthetransferredgeneticmaterialadverselyaffectshumanhealth.Thiswould
be particularly relevant if antibiotic resistance genes, used in creating GMOs, were to be trans-
ferred.Inthetechniqueoftransplantinggenes,thereisaneedforamarkertoidentifywhichcells
havetakenuptheforeigngene.Onewayistoattachageneforantibioticresistance.Followingthe
attempt to insert the new genes, antibiotics can be applied to determine which cells survive and
are therefore carriers of the implanted DNA. Once these resistant genes are into the food chain,
moredisease-causingbacteriamaybecomeantibioticresistant,increasingtheproblemsofpublic
health,asitwouldbedificulttotreathumandisease.Already,ina1999report,theBritishMedical
Associationurgedanendtoantibiotic-resistantgenesusedasmarkersinGMcrops.Asmentioned
above,theprobabilityofhorizontalgenetransferofGMplantgenesintothehumanbodyorbacteria
inthehumanbodyisverylow.Still,itisunprecedentedandcouldhavepossibleadverseaffects
onhumanhealth;therefore,withmanypeopleandmanyGMcrops,anexpertpanelfromtheFood
andAgricultureOrganizationoftheUnitedNations/WorldHealthOrganization(FAO/WHO)has
recommendedtheuseoftechnologywithoutantibioticresistancegenes(WHO2010).
ThemovementofgenesfromGMplantsintoconventionalcropsorrelatedspeciesinthewild,
referredtoas“outcrossing,”aswellasthemixingofcropsderivedfromconventionalseedswith
thosegrownusingGMcrops,mayhaveanindirecteffectonfoodsafetyandfoodsecurity.This
risk, as shown in the case of StarLink Maize in the U.S., is real; hence, several countries have
adoptedstrategiestoreducemixing,includingaclearseparationoftheieldswithinwhichGMand
conventionalcropsaregrown.FeasibilityandmethodsforpostmarketingmonitoringofGMfood
products,forthecontinuedsurveillanceofthesafetyofGMfoodproducts,arediscussedbelow.
Although traditionally U.S. regulatory agencies have been strong in the protection of human
healthandtheenvironment,GMfoodshaveenteredthemarketalmostunregulated.In1992,the
U.S. FDA determined that GM foods were usually “the same as or substantially similar to sub-
stancescommonlyfoundinfood”andarethereforenotrequiredtoundergospeciicsafetytesting
beforeenteringthemarket.Then,in1998,therewasdisclosureofapotatoexperimentbyA.Pusztai
inScotland,whopubliclyannouncedthattheresultsofhisresearchshowedthatfeedingGMpota-
toes to rats had negative effects on their stomach lining and immune system (Ewen and Pusztai
1999).Theresultingcontroversybecameknownasthe“Pusztaiaffair”andraisedquestionsboth
intheU.K.andtheU.S.aboutthesafetyofthesecrops.In2000,itwasdiscoveredthatcornbeing
usedforhumanfoodhadbeencontaminatedwithGMStarLink™Corn,whichhadtheapprovalof
theU.S.EnvironmentalProtectionAgencyonlyasanimalfeed.U.S.regulatoryauthoritiespermit-
tedthecommercialsaleofStarLinkseedwiththestipulationthatcropsproducedmustnotbeused
forhumanconsumption.Thisrestrictionwasbasedonthepossibilitythatasmallnumberofpeople
mightdevelopanallergicreactiontotheBtproteinusedinStarLink,whichislessrapidlydigested
than the version used in other Bt varieties. The StarLink corn controversy resulted in some 300
productsrecalled,masslitigationwithintheagriculturecommunity,anddropsinexportstoforeign
markets, including Japan. In the years since, farmers have had to worry about liability, markets,
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