Pesticides

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18 Apr 2012
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Genetically Modified Food
In canada, only corn, canola and soya are grown genetically modified
100% of chicken and 93% of beef served in U.S. fast food restaurants had been fed exclusively a corn
based diet
- corn coming form genetic modification
When looking at what to eat:
Must look at benefits and risks, make sure the benefits outweigh the risks.
GM- Genetically Modified
Wheat
- used to be a weed, through the ages, it has turned useful
Triticale- Wheat + Rye
Tangelo- orange + grapefruit
Species closely related- Horizontal Transfer
Non-related species- Vertical Transfer
Gene: sequence of DNA that occupies a specific location on a chromosome and determines a particular
characteristic in an organism.
DNA ---> RNA ---> Protein Synthesis
- order in which DNA bas pairs are arranged, determines code.
- first commercial use of genetic modification is in the making of cheese
- first medical use, making of insulin
- before we could synthesize, it came from animals
Cheese
- rennet tablets
- rennet found in stomach of calves
• to better digest mother's milk
- enzyme present in rennet- Chymosin
- makers of cheese running out of Chymosin
- 1990- found gene present in cows to produce Chymosin
- first commercial use of genetically modification
- Today, Chymosin made from bacteria
Benefits of GM
- output trait: deals with food composition
- use NM to modify composition of food!
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• ex. Tomatoes rich in lycopene, oils enhanced in monounsaturated fats, flax with increased
omega-3, broccoli with increased sulforaphane.
- but, would require labelling, so it's not done for marketing reasons
- input trait: -GM developed to improve production of food, not quality
- food= under attack of insects, fungi, weeds
- In the passed, pesticides were extremely toxic
- Paris Green- used by paintings, poisoned
- Black Leaf- nicotine
2nd Generation Pesticides
- Black Flag- DDT- 1946
- introduced after WWII
- food production increased x3
- pesticide used x10
- extremely effective against mosquitos (+malaria!)
- introduced to eradicate malaria in Sri Lanka
- Paul Müller- Nobel Prize in Medicine, discovered insecticidal property of DDT
- 2nd Generation of pesticides- Short term toxicity, SAFE!
-1943- Allies liberated Naples
- Typhus epidemic
- they sprayed DDT on people and stopped it!
- Long term toxicity
- may act as estrogen mimic
- early puberty
- sperm count?
- testicular cancer?
- vaginal cancer?
- breast cancer? - so prevalent because woman are exposed
- females develop earlier in North America because of estrogen mimics
- Remember: we are far more exposed to natural estrogenic mimics in our food than
synthetic ones!
- environmental impact
- Rachel Carson- wrote Silent Spring, 1962
- first environmentalist, pointed out use of chemicals and impact on environment
- because it was so effective and safe, it was used liberally
- non-biodegradabl!!! & Fat soluble!
- stays in environment, stays in fatty tissues
- finds way into lakes and rivers, picked up by algae, eaten by small fish, eaten by large
fish etc.
- bio-magnified dose of DDT
- birds with large levels of DDT had soft egg shells, would crush them when came to sit on
them!
- major effect on birds
- house flies used to be very sensitive to DDT
- Bees, thrived on DDT in Brazil
- Chemists converted DDT to DDE- not as toxic to insects
- 1969- Banned in Canada- because of environmental impact
- 1972- Banned in USA- same reason
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