Risk assessment: Bt corn MON810 Risk assessment: identifying and evaluating possible dangers...

Risk assessment: Bt corn MON810

Risk assessment: identifying and evaluating possible dangers predicting the chances the danger will occurassessing the extent of damage should the danger occur

Risk or safety assessment: AO 8science-basedtransparentcase by caseby transformation event

Absence of scientific evidence is not construed to imply safety

nor dangerRisk assessment is revisited if

new evidence is found

Concept of substantial equivalence underlies risk assessment

Substantial equivalence – identifying and evaluating danger by comparing Bt corn MON810 with a suitable comparatorComparator – isogenic line, average of trait among various varieties

Sources of risks:1.The host plant2.The donor organisms3.The transformation system4.The inserted DNA5.The genetic stability of the

introduced trait6. The inserted gene product ( expressed material)7. Potential for toxicity of the expressed material

Sources of risks:8. The potential for allergenicity of the expressed material9. The nutritional profile10. Host plant – environmental assessment11. Gene transfer to related plants12. Gene transfer to unrelated organisms ( horizontal gene transfer)13. Weediness potential14. Secondary and non-target adverse effects

1.Host plant – cornsafety of corn as food, as feed

Is there a history of safe use?Does corn contain any anti- nutrient?Does it contain a native toxin or a native allergen?How is corn used? Does processing change its nutritional profile?

2. The donor organismsWhat are the donor organisms and

their donated genes?

Toxicity – Is/are the donor organisms toxic? Do they produce toxic substances? Are the donated gene products toxic?Could these new gene products interact to become toxic?

2. The donor organismsAllergenicity– Is/are the donor organisms allergens? Do they produce allergens? Are the donated gene products allergens?Could these new gene products interact with other usual substances to become allergenic?

The transformation system

Particle bombardment vs. Agrobacterium transformation

Indirect effects due to the system: action of extraneous genes linked to the target trait,genomic modifications and rearrangements, pleiotropic effectsParticle bombardment - riskier

The inserted DNAHow much is inserted? Only the target gene? How many copies?Target genes and selective markers e.g. antibiotic resistance genes?Where is the gene inserted? CanInsertion affect increased production of native allergens? native toxins?

Genetic stability of introduced traitEmphasis on trait not DNA

Is the trait expressed from generation to generation?Is the expression of the trait through generations the same?

The expressed material/effects

Characteristics of the expressed material: size of the protein, physicochemical characteristics, sequence, etc.Level & location of the protein – levels in target/edible tissue,Bt protein level in leaves – efficacyBt protein level in grain – food safety

Toxicological assessmentBt DNA insert – not issueBt protein – expression in edible tissue, processing effects on Bt protein, history of protein, structure compared with known toxins, physicochemical properties – tolerance to heat, digestibilityBt corn – feeding studies

Allergenicity

Bt protein – source organism expression in edible tissue, immunoreactivity, sequencecompared with known allergens, physicochemical properties – Heat/processing stability, digestibility, effect of pH

Nutritional dataComparative analysis of Bt corn MON810 and isogenic lines and other commercial varieties

The host plant – environmental Assessment

Familiarity with corn – reproductivebiology, occurrence of natural hybrids with wild relatives, interaction with other organisms,origin, presence of feral types, common pests and diseasesAgricultural practices

Horizontal gene transfer – examine data on presence of antibiotic resistance genes in Bt corn MON810

Effect on non-target organisms-Use of indicator species, field trials data – effects on population of beneficial arthropods

Weediness potential

Assess whether Bt gene affected the following:Dissemination of seedsDormancy of seedsCompetitivenessAgronomic characteristics e.g. time to maturity, disease and pest resistance

Unintended effectDevelopment of insect resistance to Bt proteinPossibility of resistance development – 100%Mitigating measure – protect Bt technologyInsect Resistance management – IRM

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