1. Food Safety Assessment of GM Crops and Pesticides– Similarities & Differences
Robert Hollingworth
Institute for Integrative Toxicology

2. June 27
June 12

3. HT – Herbicide tolerance
Bt – Bacillus thuringiensis

6. Meet Cobzilla and Frankenfood

7. Method of Producing Transgenic Plants
Insertion of a “foreign gene into a plant (40,000 genes)
Selectable marker e.g.
Further plant
breeding and
selection
Final
variety
Modified Ti
Plasmid
stop
Vector transferred to Agrobacterium

8. Common GM Traits Herbicide Tolerance Insect Resistance
Virus Resistance
Stacks
Drought Tolerance
Nutritional/processing improvement
High oleic oils
Low acrylamide production
Anti-browning
B-Carotene levels (Vitamin A)
Iron fortification

9. Human Nutrition Challenges in Uganda
Micronutrient undernutrition
Micronutrient deficiencies are rated by the World Health Organisation as one of the most serious world public health problems
The major micronutrient deficiencies in Uganda are:
Vitamin A deficiency (VAD)
Iron deficiency anaemia (IDA)
Demographic and Health Survey 2006:
15-32% of children < 5 years had VAD
13-31% of women had VAD
50-80% of children < 5 years had IDA
32-64% of women had IDA

10. FDA’s 1992 Policy for Foods Derived from New Plant Varieties
Safety evaluation is based on the objective characteristics or components of the food, rather than its method of development.
Applies to all methods of breeding, including recombinant DNA
New foods are evaluated relative to their traditional counterparts
Standard is “as safe as” conventional food

11. Regulation of biotech.-derived organisms and foods in the US
Philosophy: Biotech. introduces no novel risks, so new regulatory laws are not needed. These organisms, and foods made using them, are therefore handled under existing laws.
Results: Complexity – Depends on the type of organism and modification and its intended use:
Three regulatory agencies are involved (EPA,
FDA, USDA)
Regulation is possible under as many as 10 laws.
For detailed information see:
pewagbiotech.org/resources/issuebriefs/1-regguide.pdf

12. US Biotech Regulation 1986 Coordinated Framework:
- Regulate based on product use
- Use existing laws and regulations
- Agency coordination
Environmental
Protection Agency
US Department of
Agriculture (APHIS)
Food & Drug
Administration
FIFRA; TSCA
PPA
FFDCA
Plant-Incorporated Protectants (PIPS) e.g. Bt protein; treated as pesticides
Biotech. pesticides (microbial)
Herbicide and insecticide resistance management
Import, transport,
planting of transgenic
organisms.
Food & feed safety;
Labeling
Key factor is the intended use of the product:
Food items or drugs are regulated under FFDCA
Industrial agents under TSCA , etc.

13. FDA approach to regulation of biotech foods and feeds
Food components from GM organisms are presumed to be GRAS (Generally Recognized As Safe) unless they “differ significantly in structure, fuction or composition from substances currently existing in foods”.
Manufacturers may, but are not required to, consult with FDA pre-market. However, such pre-market consultation is conducted routinely.

14. FDA’s Consultation Process
Conducted by CFSAN (plants) & CVM (animals)
Biotechnology Evaluation Team (BET) is established
Initial Consultation:
Food developer contacts FDA before market entry.
Discussion of potential issues and data needs.
Final Consultation:
Biotechnology Notification submitted by the manufacturer requesting GRAS status including required data.
Letter posted on FDA’s website. States that FDA has “no questions at this time” regarding the claims of safety in the submission. A memo describing the data and FDA’s analysis are also posted.
As with the other voluntary premanufacturing consultation processes, the FDA makes no direct statement regarding the safety of the food.

16. Core Concept of Molecular Biology
GENE (DNA)
mRNA
Transcription
PROTEIN
Translation
Direct
Effects
(Toxicity,
Allergy) ?
Metabolites
Enzymes,
Cell structure ?

17. Assessing the safety of new expressed proteins: Toxicity
History of safe use.
Protein sequence homology to known vertebrate-toxic proteins.
Toxicity when fed to vertebrates at high doses.
If pesticidal, the product is regulated by EPA as a pesticide.

18. Mechanism of insect toxicity of Bacillus thuringiensis endotoxin

19. Assessing the safety of new expressed proteins: Allergenicity
Case 1: Gene is from a known source of human allergens
Can test the transgenic protein for any reaction with serum antibodies or skin reactions in sensitive people.
Typically using genes from sources of known human allergens is avoided.

20. Assessing the safety of new expressed proteins: Allergenicity
Case 2: Novel proteins – no history of allergenicity
No single predictive test exists for allergenicity/no acceptable animal models.
Current weight-of-evidence approach with mulltiple characteristics:
Amount of protein
Stability
Heat/cooking
Digestion
Molecular characteristics of protein
Sequence homology to know allergens
Possible glycosylation
Labeling of foods (typical approach with known allergens) Regulatory caution – StarLink corn example

21. Regulatory caution – the StarLink corn example
StarLink corn was engineered to contain a Bt toxin (cry9c) that resisted digestion in the insect gut for greater potency.
Unfortunately it also resisted digestion in the human gut and thus failed the “digestibility” test in the weight of evidence.
Consequently it was not approved for human consumption in the USA, even though were no direct indications that it could cause allergies -- regulatory caution.
However, it was approved for feeding to animals – a serious error. Soon afterwards it started to be found in many corn products in human foods in the US e.g. taco shells.
Subsequent studies did not confirm any cases of allergy due to consumption of these products, but the foods were recalled. The total damages cost over $200 million.
Now GM crops are not approved for non-food uses if they are not also safe for human consumption.

22. Expected Changed metabolic pathways
Unintended effects
Expected
Changed metabolic pathways
Unexpected
Increase of endogenous toxins
Increase of endogenous allergens
Decreased nutritional quality
Other????

23. Standard Methods to Assess the Toxicity of Single
Chemicals (e.g. pesticides): Animal Tests
Animals are given very high doses of the single well-defined chemical in question compared to the expected human exposure level in order to identify any possible toxic effects. Unrealistically high doses are used because:
a. It is desirable not to miss any possible toxic effects
b. A small number of animals with low genetic variability are used in the tests
c. Humans could be more sensitive than animals
After a given exposure time (days to years) the animals are examined for a wide range of possible toxic effects.

24. Differences – single chemical vs whole food
The standard methods used for assessing the toxicity of single chemicals in animals using high doses (e.g. ADI approach) have limited utility for assessing toxic effects from whole foods because:
Foods are complex and variable mixtures of many chemicals – control diets are not identical to GM ones
Whole foods can’t be fed at high doses:
It would lead to nutritional imbalances
They often contain natural toxicants
They often are unpalatable to test animals
The results of such studies therefore have limited predictability and can be difficult to interpret in terms of the risk of any individual food component. So: If it is difficult to assess absolute safety, another approach is needed –relative safety assessment using Substantial Equivalence

25. Substantial Equivalence
Principle: If a transgenic food organism can be shown to be substantially equivalent in composition to that of a
conventional organism of the same kind, the modified
organism and its products should be judged to be as safe for consumption as the conventional ones. (OECD 1993)
The assessment of substantial equivalence is not safety testing, but it is a critical process to determine what, if any, safety testing may be necessary. It is the recommended approach of WHO/Codex Alimentarius and is used by the US, EU and other regulatory bodies.

26. Substantial equivalence: Characterization of the transformation
Description of the host plant/organism including known toxicants, allergens, nutrients and antinutrients, and its use as food.
Similar description of the donor organism(s).
Description of the transgenic plant/organism.
Description of the mode of genetic modification(s).
Characterization of the genetic modifications.
e.g. number of copies and location of the transgene, stability of integration, expression.
Assess possible effects of the transgene and plasmid components on the metabolism/metabolites of the organism.

27. Substantial Equivalence: Typical Data
Examining Substantial Equivalence – typical approach:
1. Grow the transgenic plant, non-transgenic (near isogenic), and conventional ones under identical conditions in several locations.
2. Compare their chemical composition including:
Fats, amino acids, fiber, minerals, vitamins
Antinutrients (e.g. protease inhibitors, lectins)
Known and potential toxic metabolites including any allergens
3. Conduct comparative nutritional studies in one or more animal species.
4. May add short term (3 month) dietary exposure toxicology studies in rodents if needed to resolve toxicological questions, but this is not routine (but recently required by the EU).

28. Polar Metabolites – Golden Rice
Non-Transgenic
Transgenic

29. Possible Outcomes from an Analysis of Substantial Equivalence
No significant differences are discovered. The engineered and
conventional crops are substantially equivalent. No further
study is needed to confirm safety.
A few defined differences are found. These would need
further consideration to determine the level of risk and
any further safety testing before the crop is cleared for use.
Many differences are found and/or there obvious serious
health implications in the differences. This situation would
demand extensive (and probably very expensive) further
study. The project would probably be abandoned.

30. Results from Substantial Equivalence Studies
“A recent review of 20 years of literature has shown that for the
148 GM crops approved in the US and the 189 submissions in
Japan, in every case substantial equivalence between GM crops
and their conventional counterparts was judged to have been
established. These studies covered the full range of trait
modifications and several types of crops. A large number of
academic studies also support this equivalency.”
“In addition there is ample evidence that genetic modification
results in much less alteration of crop composition than
traditional breeding methods which are generally regarded as safe.”
Herman R, and Price, D. J. Agr. Food Chem, 2013
-- also true for the European Food Safety Authority’s findings on substantial equivalence

31. “OK, but what if something else unknown has happened that’s bad
“OK, but what if something else unknown has happened that’s bad?” - Absolute and relative safety
To begin to answer this question would require extensive non-targeted analysis of the entire crop composition. And, this can be an unfocussed, open-ended and endless question.
It is impossible to prove that any human activity has zero risk and this is true of GM food products also. There is no absolute safety.
The international standard of GMO safety is “as safe as traditional foods”. USFDA’s general food safety standard is “a reasonable certainty of no harm”. Current GM foods seem to fully meet these relative safety standards.

32. CONCLUSIONS present no discoverable health risks, and we would expect
There are very few risks inherent in producing GM crops and foods that are not also common in conventional plant breeding. So logically each example of a GM crop should be evaluated for safety based on its characteristics and not its method of production.
Current GM crops and the foods produced from them
present no discoverable health risks, and we would expect
none. As far as science is able to tell, they are just as safe as
conventional food.
No well-substantiated examples of adverse health effects
have been reported among millions of consumers (animal or
human) over 20 years.

33. CONCLUSIONS Organisms producing pharmaceuticals or industrial
chemicals need careful control and segregation
from organisms intended for food use. This has been
and is is likely to be challenging. Concurrent
clearance for food use is important.
Future GM organisms may involve more complex
genetic changes and greater risks. Substantial equivalence may not exist e.g. with changes in the nutritional qualities of crops. Toxicological and
regulatory approaches must continue to evolve to
address this. This evolution is typical with most
technologies.