Potential negative impacts of biotechnology include risks to humans who eat foods derived from genetically modified plants or animals, and risk of harm to native plants and ecosystems by genetically modified plants. There is also concern that farmers' finances suffer when corporations monopolize modified seeds or other agricultural products.
Genetically modified crops are the main products of agricultural biotechnology. Another concern is hormone use in animals, such as artificial recombinant bovine growth hormone that causes infections and other health problems in cows. Studies are inconclusive about whether cancer and other possible negative health effects in humans are caused by consuming food products from animals treated with artificial hormones.
Genetically modified crops may contaminate natural plants with genetically engineered pollen and genes, create new virus strains or weeds, disrupt natural pest control and contaminate soil with toxins that may harm the food chain. These toxins may harm agricultural workers, their families and others in the community where genetically modified crops are grown.
Limiting farmers' crops to fewer, genetically engineered varieties also limits biodiversity, which is important in weathering droughts and diseases that affect plants. If there are fewer varieties or species in an ecosystem, the population is more vulnerable to a monoculture pest that could wipe out an important staple in the food supply.
Some countries where GMOs are sold lack adequate oversight and control of the organisms to protect people and the environment.