| Cadmium (Cd) is a toxic transition metal element which has many common industrial uses. Long-term exposure to Cd through consumption of food and water, the skin contact and the breath can cause renal dysfunction and osteoporosis. In recent years, the environmental problem of Cd pollution from some industries such as smelting and mining becomes increasingly severe with the society economic development. Cd pollution in soil, water and air as well as different foods has been frequently reported in China over the recent years, which produce increasing health risks for residents in polluted areas of China. When considering that many kinds of foods in markets of non-polluted areas may be produced in the polluted areas, potential health risks may exist in a number of areas without any known industrial Cd pollution. The current study about Cd health effects mainly focuses on the Cd exposed workers, which don’t have a large number of sample quantity and can’t reflect the practical situation of Cd pollution. To protect people from the adverse effects of Cd exposure, it becomes quite important to evaluate the reference level, that is, the concentration of urinary Cd (UCd) below which the probability of Cd-induced adverse health is low.In the present study, a survey involving599plant and animal samples, and1281participants in a survey area which is surrounded by a mining area in the southwest of China were carried out to investigate reference level of Cd for plant and animal samples, and UCd for renal dysfunction with urinary β2-microglobulin (UP2-MG) and Urinary N-Acety-β-D-Glucosaminidase(UNAG) as its effect indicators. Then the content and excessive ratio of Cd in plant and animal samples was evaluated. The UCd, UNAG and Uβ2-MG content of urine samples were analyzed to make a comprehensive assessment of influence on general population’s health across age and gender. The BMD value of UCd for renal dysfunction in the population was evaluated to study the effect of gender and study population on the BMD calculation. Based on the above, we use the BMDS software to estimate the benchmark dose of UCd.1. Cd concentration in environment:The concentrations of Cd in soil, water and air were below the national standard. The geometric means (GM) of Cd content in plant and animal were below the national standard, too. But the excessive ratio for tree samples was up to34.3%, for rice, tea and pig kidney samples were between20%～30%.2. UCd and its health effect indicators:The UCd concentration of more than40age group was up to6.47μg/g cr, the Uβ2-MG concentration of more than60age group was up to1043.71μg/g cr, both of them were above the national standard. The GMs of UCd、Uβ2-MG and UNAG content in man were lower than those in woman. And for those samples, the risk of excessive increased with the age of population.3. BMD/BMDL of UCd:The correlations between UCd and two health effect indicators (UNAG/Uβ2-MG) were significant (P=0.000). The UCd BMD was slightly lower in females, thereby indicating that females may be relatively more sensitive to Cd exposure than males. The UCd BMDL for Uβ2-MG was lower than that for UNAG, knowing that Uβ2-MG was more sensitive to Cd exposure than UNAG. With a benchmark response (BMR) of10%, the UCd BMDL for Uβ2-MG were2.37μg/g cr in males and1.04μg/g cr in females. The UCd BMDL were1.91μg/g cr for Uβ2-MG and2.86μg/g cr for UNAG in general population. So, Above all, the BMDL of UCd were blew the national standard (5μg/g cr). The estimated BMDL were lower than the reference level of5μg/g cr for renal effects suggested by the World Health Organization. The present results provide scientific support for a lower biological limit value for Cd exposure. |
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