EVALUATION THE POTENTIAL OF EXPOSURE PATHWAYS OF ARISTOLOCHIC ACIDS INDUCED BALKAN ENDEMIC NEPHROPATHY

Aristolochic acids (AAs) were proposed as chemicals that induced Balkan endemic nephropathy (BEN) which is a kidney disease that occurs in certain rural villages in Balkan countries. Scientists suggested the consumption of bread contaminated with AAs during the harvest may be the exposure pathway. Aristolochic acids is known as a nephrotoxic and carcinogen in human and confirmed as a cause of Chinese herb nephropathy (CHN) which is renal failure disease in patients taking Chinese herb medicine. The recent toxicological studies clearly showed the link between BEN and Aristolochic acids but the exposure pathway is still not understand. In this study, fate and transport of Aristolochic acids in soil will be explored. The sources of AAs in the area are hypothesized to be released from the plant as root exudates or their decomposed bodies to soil and we hypothesized that uptake and accumulation of AAs by crop plants may response as contaminated food. To evaluate this hypothesis, octanol-water (K_ow) and soil-water (K_d) partition coefficient was measured. The K_ow was directly measured by the shake flask method and indirectly by HPLC method. The soil sorption/desorption kinetic and isotherm was assessed by batch experiment method using soils with greatly difference of organic matter and clay contents. The plant uptake was investigated by growing the food plants in AAs nutrient solution. The results show that AA I and II were slightly hydrophilic ( log K_ow<2) under neutral condition but that they were hydrophobic in acid solution (log K_ow>4). Behavior is affected by ionization of AAs which is controlled by pH. Thus, AA can be mobile in the environment condition. The sorption isotherm was fitted well with Freundlich equation. The sorption capacity factors (K_f) had positive correlation with organic matter content but not with the clay. The linearized, organic-carbon normalized partition coefficient (log K_oc) was found to be over than 3. This means the main sorption mechanism is hydrophobic interaction between AA and functional groups of organic phase in the soil. AA was also found to sorb to dissolved organic carbon (DOC) which could enhance transport As in environment. From the K_ow and K_oc, we expect that AA will adsorb and accumulate in the plants. However, additional study is required to fully understand the plant uptake processes.