Genetically Modified Foods

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Genetically Modified Foods

• Are they safe?
• Food Safety Today and Tomorrow 78.100
• Thursday 19 Jan 2006

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• GM the public debate
• Is GM an alien unnatural technology?
• Will GM genes escape into the environment?
• Will GM crops poison the food chain?
• Will GM crops poison us?
• Will Agbiotech companies exploit the developing
  world by globalisation with GM foods?

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What is a genetically modified food?

• Food is not genetically modified
• It is made from genetically modified plants or
  animals (GMOs)
• Most agricultural crops are genetically different
  from their original ancestors
• How is the genetic variation derived?
• What is natural?

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From DNA to Action

• What we are is controlled by our genes
• A gene is a piece of DNA that provides a code
  that makes one of more proteins or a part of a
  protein
• Proteins form structural components of the body
  and/or perform biological functions
• Genes are packed into chromosomes
• Genes mutate all the time and can be switched on
  or off

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Genes mutate?

• DNA is made up of two complementary long strings
  of nucleic acid bases twisted into a double
  helix
• There are four bases, Adenine, Cytosine, Guanine,
  and Thymine
• Each group of three bases specifies one of twenty
  amino acids
• One gene may be 2000 to 15000 bases long
• The order of the amino acids in a protein control
  its shape and function

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• A mutation can occur when just one base is
  changed
• When a cell divides it reproduces its DNA
• A bacterial cell may reproduce 100 million times
  before there is a 5050 chance of a mutation
  occurring
• Not all DNA specifies protein, some stretches
  control the process. Some DNA appears to be
  redundant

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• Sexual reproduction leads to variation because
  the parental genes are mixed and some are
  expressed and some are not
• Plant breeding is based on trial and error of
  mixing genes from parent plants and observing the
  results
• Genetic modification deliberately targets adding
  or deleting specific genes to an organism

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• Conventional breeding of short stemmed rice
  increase yields from 1.5 to 4.0 tonnes/Ha between
  1967 and 1985
• Yeast contains 30 m bases in its DNA and 6000
  genes
• People have 3000 m bases and 200000 genes
• Wheat has 32000 m/100000, Maize 3000 m/100000,
  rice 450m/75000

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• Make or select DNA for new gene
• Deliver by biological, chemical or physical
  method into a single cell
• Multiply the cell
• Identify cells containing gene
• Grow up to whole plant
• Check stability and expression
• Develop breeding line

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Their shoes were clean and neat.
Darwin understood the power of artificial
selection upon crops and domesticated animals
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Divergent EVOLUTION
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Hey Oysters, yeah, Come and rollerblade with
ourselves, yeah" The Walrus invited robustly. A
wicked walk, a brilliant talk, yeah, Right along
the salty beach, yeah Four of yourselves will be
cool, yeah That way myself and the Carpenter can
give each a hand yeah, Sorted, yeah"
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Agricultural Revolution 10,000 years ago From
Neolithic Hunter-Gatherer to Domesticator-Cultivat
or performing genetic modification by artificial
selection Artificial Evolution
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• Conventional plant breeding involves randomly
  mixing genes from one plant variety with another
  by cross-pollination
• GM uses copy and paste to move target genes
  from one plant to another
• GM can be within species - like non-sexual
  conventional breeding
• OR GM can be between sexually incompatible
  species
• GM is highly regulated

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Crop Domestication Opposition to Tomatoes
In the nineteenth century, the tomato was known
as the wolf's peach, and Europeans and Americans
believed it was deadly poisonous. In 1820, New
York forbade its consumption and only relented
when Colonel Robert Johnston announced that he
would eat an entire bag of them outside the
courthouse in Salem, New Jersey. Two thousand
people turned up to watch him die, while a band
played a funeral march. But Johnston ate the lot
and announced 'This luscious, scarlet apple will
form the foundation of a great garden industry.'
The Observer, Sunday, January 23, 2000
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Why modify plants?

• Increase disease resistance
• Increase yields
• Improved nutritional properties
• Improved shelf-life
• Decreased dependence on chemicals
• Increase growth range

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Cost of crop disease

• World crop loss due to all disease 25
• Control of insect and fungal pests - 8.7bn
• In US alone
• Lepidopteran pests cost 400 m
• Colorado beetle and Corn rootworm cost 1bn
• Insect loss of cotton cost 645 m
• Hence the economic pressure to develop insect
  resistant crop plants (Bt gene)

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What GM foods are there?

• Fast maltose fermenting yeast (1990 - never used)
  
• Chymosin (calf gene expressed in yeast)
• Tomatoes (delayed ripening) and paste
• Soya (herbicide tolerant - 65 of US production -
  approved 1996)
• Maize (insect resistant)
• Oil seed rape (herbicide tolerance)

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Tomatoes

• Ripening in tomatoes is complex
• Switching off the gene for polygalacturonase
  delays softening but not ripening
• GM tomato lower viscosity, lower water use and
  chopped tomato retains juice better (thicker
  paste)
• Approved USA 1995, UK 1995, Canada 1996, Mexico
  1996.

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Safety in GM Food

• the use of the principle of substantial
  equivalence in the safety assessment of GM foods
• possible effects of GM foods on human nutrition
• possible effects of GM foods on allergic
  responses
• potential effects on human health resulting
  from the
• use of viral DNA in plants
• the fate of GM plant DNA in the digestive
  system.
• http//www.royalsoc.ac.uk/document.asp?tip0id14
  04

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So are GM Foods Safe?

• Threat to human health
• Pusztai and potatoes and lectins
• Gasson and Burke
• Allergens
• Pollen
• Infant formula
• Golden rice
• Threat to environmental health
• Super weeds
• butterflies

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Substantial equivalence

• Equivalent to what
• How much equivalence
• Conventional breeding
• Psoralens in insect resistant celery
• Solanine in Magnum bonum potato in cool weather
• A starting point
• Vulnerable groups

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Allergens

• 1 - 2 adults, 6 -8 children
• Anaphylactic shock 3 in 100000 per year
• Food allergens tend to be proteins

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Viruses

• Viruses are used to insert genes
• We eat plants infected with viruses every day
• In humans, approximately 1 of total DNA is
  composed of integrated viruses, but only one of
  these viruses, HERV-K, may be active (Turner et
  al., 2001).

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DNA

• 600 kg cow is estimated to ingest about 600 mg of
  DNA a day
• Given the very long history of DNA consumption
  from a wide variety of sources, it is likely that
  such consumption poses no significant risk to
  human health, and that additional ingestion of GM
  DNA has no effect. Consequently, it is unlikely
  that the ingestion of well-characterised
  transgenes in normal food and their possible
  transfer to mammalian cells would have any
  significant deleterious biological effects.

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Royal Society Recommendations

• Safety assessments should continue to consider
• potential effects of the transformation process.
  The
• phenotypic characteristics to be compared between
• foods derived from GM plants and their
  conventional
• counterparts should be defined. It may not be
• necessary or feasible to subject all GM foods to
  the full range of evaluations but those
  conditions that have to be satisfied should be
  defined.

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Research should be undertaken to develop modern
profiling techniques and to define the normal
compositions of conventional plants. The working
group welcomes the funding initiatives already
put in place by the European Union Framework V
programme and the UKs Food Standards
Agency (FSA).
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• The biotechnology industry should collaborate
  with academia and regulators to develop and share
  suitable reference data sets. This will help
  ensure that the new technologies are wisely
  applied and that agreement is reached on the
  appropriate interpretation of the data that they
  will generate.

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• The UK Government should review the enforcement
  of the regulations on infant foods and GM foods
  to ensure these regulations are complementary.

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• The current decision trees used to assess allergy
  should
• be expanded to encompass inhalant as well as food
• allergies.
• In the longer term, should GM foods be
  re-introduced
• into the market in the UK, we suggest that the
  Food
• Standards Agency considers whether post-marketing
• surveillance should be part of the overall safety
• strategy for allergies, especially of high-risk
  groups
• such as infants and individuals in atopic
  families.

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Friends of the Earth

• The Royal Society of Canada report (2001)
  discusses this in depth and conclude that
  substantial equivalence is not supported by
  scientific rationale.
• there are differences in lignin, carbohydrate,
  fat and phyto-oestrogens between Roundup Ready
  soya and its non-GM counterpart.
• T25 maize the level of two fatty acids falls
  outside the range seen in traditional crops

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Greenpeace

• the potential for complex effects from the
  alteration of a single gene is much greater than
  previously thought and must be considered.
• unpredictability is a major concern.
• the potential to transfer genes from diverse
  species means there is an increased likelihood of
  surprises
• testing every new GM crop on animals would not be
  useful.
• basic message is its risky and we dont know how
  to measure it.

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So is GM food safe

• ?