Farming

• One incentive for farmers to plant genetically modified seed is its resistance to herbicide. One consequence of planting GMO crops is that farmers can use herbicide less discriminately, resulting in more herbicide soaking into the earth. A more recent consequence is the emergence of herbicide-resistant weeds. Instead of rotating crops and allowing the soil to recover, farmers use more chemical fertilizers designed to work with the modified seed to artificially provide the nutrients plants need. Another consequence is that organic farmers' fields are contaminated by GMO plants as birds or insects from a neighboring GMO field naturally pollinate their crops.
  
  

Health

• Health consequences of consuming genetically modified foods are unknown. A 2007 study by scientists at the University of Central Florida showed that lettuce that was genetically modified to produce insulin could have the potential to cure Type-1 diabetes. On the other hand, consumers report severe allergic reactions including hives and other immune system disorders after eating foods containing genetically modified organisms. In "The World According to Monsanto," Marie-Monique Robin explains that manufacturer's testing of glyphosate --- a key ingredient in herbicides --- show that it is not harmful to mammals because it cannot penetrate cell walls. However, in proprietary blends of herbicides, glyphosate is mixed with dispersants and detergents that enable it to penetrate cell walls. A 1997 study published in the "American Journal of Epidemiology" links herbicide use in Ontario, Canada with increased incidence of late spontaneous abortion. Additional research by Professor Eric-Giles Seralini of Caen University in France link herbicide use with increased incidence of lymphoma and multiple myeloma.
  
  

Food Supply

• As large commercial suppliers of genetically modified seed seek to sell more of their patented product, the choice of seed varieties available to farmers and other consumers decreases. Cary Fowler and Pat Mooney report in "Shattering: Food, Politics, and the Loss of Biodiversity" that the National Seed Storage Laboratory (NSSL) --- the largest seed bank in the United States -- housed 497 varieties of commercially-available lettuce in 1903. By 1980, the NSSL only had 36 varieties of lettuce. Fewer varieties can have disastrous consequences to the world food supply in the event of a disease that decimates the remaining varieties.
  
  

Legal Consequences

• Monsanto is one of the biggest producers of GMO seeds. Monsanto patents the seed it sells after adding to or modifying the plant's genes. Writer Michael Pollan says that farmers must sign a contract with Monsanto that gives the company the right to inspect plants in the field to prove they are Monsanto's intellectual property. Farmers must also agree not to save seed from their crops to plant in subsequent years. Monsanto sued Canadian farmer Percy Schmeiser of Saskatchewan when his fields were contaminated with Monsanto products by natural pollination.