[Risk factors in human food chain]

Heavy metals are found in various forms and concentrations in soil. Total content, releasing potential, movement and forms of the risk elements in the soil have been detected in experimental practice. Fytotoxic effects of heavy metals depend mainly on the concentration and the amount of available form of element in soil solution. Numerous studies have described a negative impact of heavy metals on plants and animals. Contemporary knowledge confirms that the risk degree of the heavy metals on plants depends on their "stress effect". Recent research has pointed out the serious impact of heavy metals on microorganisms in soils with negative consequences on cycles of nitrogen, carbon, sulfur and phosphorus. Contamination of vegetable with the toxic elements and consequently the man food is serious problem occurring mainly in industrial areas and agriculture where industrial fertilizers with high content of lead, cadmium, arsenic, chromium and mercury are used. Other metals as zinc, nickel and aluminum maz pass to the foodstuff through the packing materials. During the year 1999 sixty samples and 420 analyses of heavy metals were processed in soil and green feed from area close to metallurgic plant. There were not found any increased levels of the toxic elements if compared with maximum allowed concentrations. If a maximum limit is 100% then relative concentrations of evaluated elements in the study averaged as follow: iron 29%, lead 312%, copper 32.8%, cadmium 38.5%, manganese 65.2%, zinc 73%. No significant differences were found if compared with control area. Values of transition coefficient were under 0.5 in lead, cadmium, nickel and iron, but higher than 1.0 in copper, zinc and manganese. Although a risk evaluation of soil and green food in this area seems to have less risk value, the concentrations of the risk elements in organs of farm animals in the same area were over the maximum limit in 7% of total analyses. The highest concentrations of cadmium, lead, arsenic, zinc, mercury and chromium are detected mainly in older and wild animals. This is due to the ability of toxic elements to accumulate gradually in the animal body. Muscles are generally known to accumulate the lower levels of metals except metylmercury. In animal products heavy metals are mostly detected in liver, kidney, bone and milk. Anthropogenic emissions of the air contaminating substances are the main reason of the present and potential health disorders. Accumulation of silicon, lead, nickel and manganese in liver, kidney, cells of lungs and reproductive organs has been evaluated. Chronic glomerulonephritis with subsequent ultrastructural changes in glomerules and tubules were found in kidney. In liver, focal infiltration with mononuclear, necrotic areas and dilation of central veins is reported. Excessive hyperemia, proliferation and edematization of endometrium and glandular atrophy can be found in uterus. Higher frequency of atretic follicles in ovary is obvious. Infiltration of lymphocytes, occurrence of detritus in bronchi, interstitial pneumonia and emphysema has been found in lung. Basic trend in modern human nutrition lays in interrelation among nutrition, health and diseases. Generally, modern chronic diseases such as obesity, coronary and heart diseases, diabetes, hypertension, cancer and osteoporosis result form excessive intake of energy combined with insufficient intake of essential elements. To solve this problem, futher research is needed for understanding the mechanism of diseases that result from environmental factors such as heavy metals