What about GM crops and antibiotic resistance?
When plant cells are genetically modified in the laboratory, additional pieces of genetic material are combined with the primary genes in order to make the successfully transformed plants more easily detectable. These additional pieces of DNA are called selectable markers and may for example make the plant cells a particular colour or make them capable of growing in the presence of certain molecules which would normally inhibit growth. These genes are used in the early stages of selection, but remain in later generations of plants, where they serve no function. In the early days of crop biotechnology, antibiotic resistance marker genes (ARMs) were often used as the means of selection. Some crops bearing this gene are still grown and no credible concerns have been raised about their potential to cause greater bacterial antibiotic resistance.