Cadmium and lead bioaccumulation in broilers fed on rations containing high concentrations of Cd and Pb was studied. The degree of bioaccumulation was assessed by using klark of concentration (Kc). It was established that the 100 and 200 fold increase of lead and cadmium in the ration resulted in their increase in the muscles, the bones and the liver, but the degree of bioaccumulation was considerably lower than the increase of both of the heavy elements in the ration indicated by the lower Kc. A conclusion was drawn that the organism possesses adaptation mechanisms for limitation of cadmium and lead bioaccumulation through these mechanisms are not efficient enough for high ration doses of both elements. High ration doses resulted in bioaccumulation exceeding the safe for humans concentrations of lead in the bones and of cadmium in the muscles (for doses 200 fold higher than the highest Bulgarian State standard 13426-77 permissible concentrations /HPC/) and in the liver for doses 100 fold higher than HPC.

Studies on the degree of microbial atmospheric pollution caused by industrial broiler breeding were carried out. The experiments were performed with broiler chickens bred on litter that was not changed, at a density of 20 chickens m−2 in uniform buildings each possessing a total area of 960 m2. A gradual increase of the microbial numbers in the indoor air was observed as the birds aged (1.25×103 to 1.68×105 m−3 air). The ageing of the birds was also accompanied by a more massive emission of microorganisms into the environment (2.86×109 to 3.05×1013 emitted in the air over 24 h per building). These studies, concerning the problems of microbial pollution caused by the industrial breeding of farm animals, indicate that the microorganisms could be dispersed by air flow for up to 3000 m from the production buildings.

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