Estimation of non-dietary cadmium exposure and risk associated with it in farm community living in Mae Sot, Tak province

Abstract

The non-dietary exposure of cadmium (Cd) among farm community in Mae Sot district, Tak Province and its risk associated was estimated by using an in–vitro oral bioaccessibility method comparing with the control site. Total Cd concentrations in soil were ranged from ND-162 mg/kg. For residential and agricultural areas, the Cd concentrations in soil were ranged from ND-156 mg/kg and 1.32-162 mg/kg, respectively. Bioaccessibility of Cd was ranged from 8.6-96.0%. Average daily intake of soil cadmium via incidental soil ingestion among farmers, normal adults (non-farming), children aged 6-8 years and younger children aged 1-5 years were 3.47, 0.95, 1.9 and 3.8 µg/day, respectively. When the intake estimations were adjusted with body weight, the intake among men and women farmer were 0.35 and 0.42 µg/week/kg BW, respectively. The intake among normal adults men and women (non-farming), children aged 6-8 years and young children aged 1-5 years were 0.10, 0.12, 0.70 and 2.0 µg/week/kg BW, respectively, which contribute to a considerable amount of tolerable intakes (TI-s) set by US.EPA. The results indicated that Cd intake via incidental soil ingestion pathway alone in children aged 1-5 years may contribute to high percentage of TI-s and sometimes exceed the TI-s. Therefore, Cd intake among young children is needed to be surveillance. The Cd concentrations in soil and Cd intake via incidental soil ingestion in the contaminated site are significantly higher than those in the control site. Since bioaccessibility is site-specific, the nature of bioaccessible Cd was determined. The bioaccessible Cd in soil in the contaminated site behaved similar to Ca, Mg and Zn at p < 0.01, significantly. Ni might compete in dissolution with Cd in the gastric environment (negative correlation at p < 0.01, significantly). A significant positive correlation of bioaccessible Cd with bioacessible Ni (p < 0.01) confirmed the possibility of competing Ni with Cd Bioaccessible Cd showed a weak correlation with organic matters at p > 0.1 indicating that organo-Cd complexes in the site might be somewhat bioaccessible.