As with every other thing that is produced as part of a product/payment process, genetically modified crops can give a big blow to farmers all around the world in that the product that they already have set to grown and cultivate might be in danger of not being consumed. This will impact the economy of many cities and countries, especially those who depend on the export of certain crops. For example, if potatoes were to be genetically manufactured in California, Idaho would lose its main produce and their economy (and job opportunities) will go down the drain. This is the ethical issue to deal with.
In a moral level, to which point can scientists reproduce what is already naturally available? Many feel that this could result in a basic disrespect of mother nature, not to mention that if the crops lose any of their original nutrient value the entire world could become equally affected.
Finally, health wise, a study in Europe pointed out that some GM crops affected bees in certain ways, which will affect pollination and the natural progression of things in the food chain. Speaking of the food chain, humans may develop new allergies to the genetically modified foods since they will lose or change a lot of their original genetic make up. Not enough tests nor exposure to these foods can correlate to any possible future negative reactions to them, so we need to keep a close look at trends in research in the future.
With crops, most of the concerns raised would fall along the lines of safety or health issues. What are the possible negative health effects of messing with the genetic structure of things that humans then consume? Is it dangerous on any level? Can it impact our own genetic structures, or cause things like cancer or illness? So those are some concerns that might be raised. Another argument might be a religious one, that if God didn't make it, then it isn't natural and shouldn't be done. They might say that people are trying to "play God," and that that is irreverent and dangerous. If devout believers in God believe that He created the earth and everything on it that was necessary for people to thrive, then altering things is unnecessary and taking too much power into our hands.
Other concerns might fall along the lines of the environment; does altering these crops require the use of chemicals or stimulants that are harmful to the atmosphere or environment? How does planting these crops impact the ecosystem of where they are planted. So their produce and by-products harm the earth in any way, or people that consume them? Long-term studies would have to be conducted on all levels of safety in order address these issues.
I hope that those thoughts can help to get you started; good luck!
Genetic modified crops is a scientific reality today. Also the economic benefits of this technology are also well established. The ethical issues related to this field center around two concern. One is the creation and wide use of genetically modified food and other products that may result in unexpected problems for the user as well as other crops. Second is the unethical commercial practices associated with companies that sell seeds and other products for production of genetically modified crops.
It is believed that genetically modified crops are introduce in the market with insufficient understanding of the impact of such crops on other crops and on health of people. For example, it is alleged that some genetically modified crops are too prone to plant infection and these can lead to spread of plant infection to other varieties with disastrous results. Similarly it is alleged that absence of some nutrients and presence of some other harmful ingredients in food item can cause serious health problems.
Also the companies marketing seeds and other products for growing genetically modified crops are purposely engaging in development and marketing of products that is designed to establish and perpetuate their monopolistic control. Indulging in monopolistic practice is illegal in most of the developed and developing countries, but these companies have not come under the ambit of the relevant laws so far. For examples companies sell seeds that produce plants without seeds. I this way companies ensure that they will always maintain the monopoly over production and sale of seeds. Use of monopolistic practices in food products and other bulk agricultural products used by masses can be particularly objectionable as per ethical considerations.