A potential hazard in current experiments derives from the need to use a bacterium like [Escherichia coli] to clone the recombinant DNA molecules and to amplify their number. Strains of [E coli] commonly reside in the human intestinal tract, and they are capable of exchanging genetic information with other types of bacteria, some of which are pathogenic to man. Thus, new DNA elements introduced into [E coli] might possibly become widely disseminated among human, bacterial, plant, or animal populations with unpredictable effects.
In Bulgaria, extensive field trials of bacteria- and virus-resistant tobacco have been grown since 1991, with no regulations and local public awareness. Other transgenic plants are being grown in field trials in Hungary and Russia.
Early experiments to breed larger-than-normal animal species by the use of the insersion of human genes have proved successful, with mice growing to twice their normal size at twice their normal rate. In Poland, genetically engineered carp with human growth hormone genes have been swimming in ponds for several years, separated from the wider environment only by a filter.
In 2000, scientists transferred a foreign gene into a rhesus monkey.