Descripción: In recent years, there has been growing concern regarding the occurrence of bromate (BrO3-) into the environment. Bromate is classified by the International Agency for Research on Cancer (IARC) as a compound with carcinogenic potential (Group 2B) which has resulted in strict international regulations in drinking water (10 ug L-1). Contamination by bromate (non-natural) is commonly associated with disinfection by-product (DBP) formation during the treatment by ozonation of drinking water containing background bromide concentrations. Bromate cannot be easily eliminated using conventional treatment technologies due to its high solubility and stability in water and its weak sorion characteristics to common soils allowing it to be a mobile and persistent pollutant in the environment. Previous results obtained from our project (FONDECYT ) shown that bromate is found naturally in soils, drinking water, fruits, and vegetables mainly in northern Chile. Interestingly, relatively high concentrations of bromate (two and three time higher than perchlorate) were found in fertilizers (nitrogenous, non-nitrogenous and phosphoric) produced and marketed in Chile. In this context, in fertilized soils, bromate levels in soil and vegetables are higher than in unfertilized soils, indicating a probable effect of fertilizers. Fertilizers are known to increase the productivity of crop systems, however, their entry into soils is massive and little control, not knowing its effect on the dynamics of bromate in agricultural soils. In this scenario, levels of bromate in fertilizers, irrigation water and soils can be uake by plants (leafy vegetables 90% water Fresh weight) reaching the edible parts of food crop and finally enter the food chain. In Chile, vegetable production is mainly concentrated between the IV, V, VI and Metropolitan (MR) regions, specifically for lettuce (consumed by almost all age groups), spinach, and chard (consumed preferentially by pregnant women, babies, and infants), mainly in baby foods or prepared at home). The World Health Organization (WHO) established that the main routes of exposure to bromate is through consumion of food contaminated by chemical agents (fertilizers) and drinking water, thus generating an increase in the incidence of chronic and severe diseases in the world. Faced with the current global scenario of water scarcity, reduction of arable land and greater dependence on fertilizer use, no methodical approach has been carried out in Chile to determine the impact of such contamination in the agricultural system (soil-plant). In this project, it is proposed to generate experimental data to understand the dynamics of bromate in the soil-plant system under different scenarios field, substrate (greenhouse) and hydroponic conditions using spinach, chard and lettuce under two types of fertilizers (nitrogenous KNO3 and Urea). The data in this proposal consists of 4 critical experiments 1) Field research under manual fertilization and fertigation, aimed at evaluating the differences in the uake and accumulation of bromate in 3 leafy plant species (spinach, chard and lettuce) in three regions (V, RM and VI regions) with the application of 2 types of nitrogenous fertilizers (KNO3 and Urea). 2) Greenhouse (substrate) Under fertigation conditions using KNO3 and Urea, we propose to elucidate the final destiny of bromate in the system (water-substrate-plant) and to estimate differences in accumulation rates in lettuce, chard and spinach. 3) Hydroponic research in order to estimate whether the rate of bromate uake in absence of soils (considering a low soil affinity) can be used to predict its final content using lettuce, chard and spinach using KNO3 and urea. 4) Explore the transport of bromate in agricultural soil the research will be carried out evaluating the risk to leach from the agricultural soil to the underlying aquifer. All samples will be analyzed by liquid chromatography with a mass detector (LC-MS/MS). The results generated in the 4 critical experiments will be used to understand the fate of bromate in soil-plant system, generate predictions in time and to estimate the daily intake doses for each scenario according to age group. Our project is the first research worldwide to evaluate the mobility and final fate of bromate in the water-soil-plant system.
