The paper shows the selected factors that are produced by men and that influence health quality of animal feeding stuffs, food safety and environment protection. It also presents hazards that arise as a result of faulty or incorrect use of legal acts or therapeutic premixes; a lack of knowledge about the interaction between therapeutic products and feed, the problem of the influence of genetically modified organisms on animals or antibiotics themselves on the environment. The effects of the described substances, that enter animal organism at very low doses that evoke subclinical picture of diseases and / or that cumulate in them, were underlined. Aberration of homeostasis in three principal systems in the organism (hormonal, immunological and nervous systems) may be the subsequent consequence. This condition can lead to the prevalence of a particular disease evoked by the mentioned factor or it can provoke the virulence of the pathogen that is present in the organism as saprophyte or as a result of the contact with exogenous pathogen. The summary suggests executing the binding law regarding particular feed additives (e.g. antibiotics) more effectively and considering the results of scientific research. The materials admitted to use and feed additives in feeding of farm animals should be evaluated more perspectively and multidirectionally. This estimation ought to be carried out regarding also all the consequences of the influence of these substances on health of animals and consumers of food of animal origin and the influence of wastes of animal or feed origin on the environment.