GMOs: dangers to the health and the environment.

First of all, what does GMO mean? Its meaning is Genetically Modified Organism, namely an organism whose genetic material has been altered using genetic engineering techniques. 
There are two main kinds of GMOs: the industrial ones and the alimentary ones. 

Regarding the industrial GMOs, there are pros and cons. Of course the GM textile fibers are more resistant, the GM plants require a lesser amount of water and textile fibers such as cotton can grow already colored, so there is a minor use of industrial dyes, which are toxic to the marine ecosystem; but what are the negative aspects? There is a serious danger of dispersion of GM seeds in nature, there could be allergies to the new GM tissues and the multinationals producing GMOs have created a lobby. 

As of the alimentary GMOs, the objectives of the genetic modification are making animals and plants more productive, making them more resistant to deseases and pests and making them grow faster. 
However, there are some perils such as a quite high risk of human allergies to the new products, dispersion of animals and plants in nature going to occupy ecological niches of "real" animals, replacement of GM plants and animals to the natural ones. 
Furthermore, the GMOs lobbies are making more and more expensive the products, making sterile animals and plants so as to oblige farmers to buy every year their products and seeds.