Why are the recombinant DNA technology and the nucleus transplantation technology still dangerous?

The recombinant DNA technology and the nucleus transplantation technology (cloning) are extremely dangerous as they are able to change, in a very short time, the ecological balance that evolution has taken millions of years to make on the planet. During the evolutionary process, under the slow and gradual action of mutations, genetic recombinations and of natural selection species emerged and were changed and genetic patrimonies were formed. With genetic engineering however humans can mix and modify genes, making alters of unpredictable long term consequences, risking creating new plant or animal diseases, new types of cancers and new disease outbreaks. It is a field as potentially dangerous as the manipulation of nuclear energy.