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

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