UNIVERSIDADE DE SÃO PAULO CENTRO DE ENERGIA NUCLEAR NA AGRICULTURA

GUERRA, F. Cadmium in food chain: derived from vegetables and evaluation of its availability in soil with the aid of Cd. 2011. 94 p. Dissertação (Mestrado) – Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, 2011. The environmental contamination is increasing world wide, with large areas affected by heavy metals at concentrations which may pose environment al hazard. Due to industrial activity and highly technical agriculture, it is important to mo nitor heavy metals levels in soils, since vegetables behave as transfer mechanism of contamin ants from soils to higher levels of the food chain. Ingestion of vegetables containing high concentrations of heavy metals is one of the main ways in which these elements enter the hum an body. Once in human body, heavy metals are deposited in the bone and fat tissues, o v rlapping noble minerals. Slowly released into the body, heavy metals may cause an array of d iseases. The project was divided into three stages, each one with a specific objective: 1 ) to determine the concentrations of cadmium, nickel, lead, cobalt and chromium in the most frequ ently consumed foodstuff in the São Paulo State, Brazil and to compare the heavy metal conten ts with the permissible limits established by the Brazilian legislation; to calculate intake o f heavy metals in human diets for estimating the risk to human health; and to identify crops wit h the greatest potential for translocation of cadmium into food chain 2 ) to evaluate the cadmium content in leafy vegetabl s and soils at crop fields 3) evaluate the phytoavailability of cadmium for lea fy vegetables with aid of chemical extractants and radioactive tracer techniq ue (Cd). The vegetable samples were collected at São Paulo General Warehousing and Cent ers Company, and heavy metal content was determined by atomic absorption spectrophotomet ry. All vegetables sampled presented average concentrations of Cd and Ni lower than the permissible limits established by the Brazilian legislation. Exception for Pb and Cr in t hat 44% of the samples exceeded the maximum permitted limits. The Brazilian legislation has not established a permissible limit for Co contents. Regarding the consumption habit of the population in the São Paulo State, the daily ingestion of heavy metals is below the or al dose of reference, therefore, the consumption of these vegetables can be considered s af and without risk to human health. Leafy vegetables were those most accumulated Cd. So me regions of São Paulo State showed total contents of Cd in soil higher than interventi o value established by CETESB. However, the vegetables grown in these areas showed Cd conce ntrations lower than Brazilian limit established by ANVISA. It is important, when studyi ng environmental contamination by heavy metals, to observe, beside their total conten t, other parameters, like soil availability. In the greenhouse experiment, the correlation between soil available Cd and plants accumulated Cd were significant only for rocket. The most effic ient chemical extractant in determining Cd phytoavailability, analyzed by L Value and L Ratio, were Organic Acids.