SELENIUM IN THE ENVIRONMENT

Selenium is an element that is of interest to many researchers. As a trace element, it occurs in all compartments of the natural environment. It can be found both in an organic and inorganic form in water, rocks and air. For a long time, this element had been identified as a hazardous substance due to its toxicity. It was only in recent years that the physiological need to use it as a micronutrient fundamental to the health of humans and animals was noticed. However, it is not necessary for the growth of plants. In appropriate doses, selenium significantly affects the health of humans and animals because it is a component of many enzymes and it has antioxidative and anticancerogenic activity, but in excessive amounts it exhibits a toxic effect and causes a disease called selenosis. Its deficiency, however, is a much greater problem. It may occur in people living in most areas of the world. Selenium is an exogenous element, which is supplied to the human organism with food. Because plants are the main source of this element, it is important to increase its plant level. This can be achieved in different ways. One of the most promising approaches in addressing the problem of a low level of Se transfer from soil to the food chain is the agronomic biofortification of Se. Other interesting solutions are genetic engineering and the use of naturally selenium-rich materials. A new approach to fertilization of plants with Se is the use of nanomaterials. However, an excess of this element can induce toxic effects, such as the growth inhibition, wilting and drying of leaves, reduced protein synthesis and death of immature plants.