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Risk assessment: Bt corn MON810
Risk assessment:
identifying and evaluating possible
dangers
predicting the chances the danger
will occur
assessing the extent of damage
should the danger occur
Risk or safety assessment: AO 8
science-based
transparent
case by case
by transformation event
Absence of scientific evidence
is not construed to imply safety
nor danger
Risk 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 comparator
Comparator – isogenic line,
average of trait among various
varieties
Sources of risks:
1.The host plant
2.The donor organisms
3.The transformation system
4.The inserted DNA
5.The genetic stability of the
introduced trait
6. 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 material
9. The nutritional profile
10. Host plant – environmental
assessment
11. Gene transfer to related plants
12. Gene transfer to unrelated
organisms ( horizontal gene transfer)
13. Weediness potential
14. Secondary and non-target
adverse effects
1.Host plant – corn
safety of corn as food, as feed
Is there a history of safe use?
Does corn contain any antinutrient?
Does it contain a native toxin or a
native allergen?
How is corn used? Does processing
change its nutritional profile?
2. The donor organisms
What 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 organisms
Allergenicity– 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
effects
Particle bombardment - riskier
The inserted DNA
How 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? Can
Insertion affect increased
production of native allergens?
native toxins?
Genetic stability of introduced
trait
Emphasis 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 – efficacy
Bt protein level in grain – food
safety
Toxicological assessment
Bt DNA insert – not issue
Bt protein – expression in edible
tissue, processing effects on
Bt protein, history of protein,
structure compared with known
toxins, physicochemical
properties – tolerance to heat,
digestibility
Bt corn – feeding studies
Allergenicity
Bt protein – source organism
expression in edible tissue,
immunoreactivity, sequence
compared with known allergens,
physicochemical properties –
Heat/processing stability,
digestibility, effect of pH
Nutritional data
Comparative analysis of Bt corn
MON810 and isogenic lines and
other commercial varieties
The host plant – environmental
Assessment
Familiarity with corn – reproductive
biology, occurrence of natural
hybrids with wild relatives,
interaction with other organisms,
origin, presence of feral types,
common pests and diseases
Agricultural 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 seeds
Dormancy of seeds
Competitiveness
Agronomic characteristics e.g.
time to maturity, disease and
pest resistance
Unintended effect
Development of insect resistance
to Bt protein
Possibility of resistance
development – 100%
Mitigating measure – protect Bt
technology
Insect Resistance management –
IRM
Thank you
for your kind
attention