Concern relates to personal philosophy, perception of risks and familiarity with biology. Areas of concern include:

• Change in one area will impact the entire ecosystem. No one really knows what will happen. People can not anticipate and control all potential risks of gene transfer.
• Humans do not have the right to modify plants or animals. Only those changes which occur "naturally" without human intervention should be permitted.
• All products should be tested for human and environmental safety. This should include long term animal feedings and clinical human tests and extensive crop field testing.
• The social and economic consequences of changes in biotechnology are inadequately evaluated.
• The development of pesticide-resistant plants may cause farmers to use pesticides more frequently if the pesticides do not harm the agricultural crop. Alternatively, weeds could become resistant to pesticides.
• The scientific techniques of making changes in DNA are subject to patent laws. Critics of this technology believe this enables companies to "patent life."

For more information on concerns over biotechnology, see the Union of Concerned Scientists