The Relationship Between The Level Of Population Exposure To Cadmium And Kidney Damage In Cadmium Contaminated Area

[Objectives]To find out the cadmium exposure level and renal damage situation of population in environmental cadmium contaminated area, and the changes of urinary cadmium and some health indicators related to renal injury,such as urinary NAG and urinary β2-M, in different cadmium exposure levels.[Methods]Data of dietary and health survey for the subjects in this paper originated from 《The survey report of environmental cadmium pollution and population health situation in Hezhang county, Guizhou Province》,which was completed by environment institute of Chinese Center for Disease Control and Prevention in2010, and the project has got the acceptance of The Ministry of Environmental Protection of China.A three-day dietary survey was made for201families which contained546local people to get the dietary data. Combined the dietary data with the cadmium contents of main crops samples, we could estimate the population dietary cadmium exposure levels. And then carrying out population surveys of health damage in the contaminated area and control area and collecting urine samples of subjects (contaminated area:948copies, control area:403copies), we could evaluate the renal function status of local population by detecting urinary cadmium, urinary NAG, urinary β2-M and the other indicators in urine. At last we explore the change of urine indicators among the different levels of environmental cadmium exposure.Cadmium contents of the crops samples was detected by graphite atomic absorption spectrometry; urinary cadmium was detected by inductively coupled plasma mass spectrometry (ICP-MS); urinary NAG was detected by spectrophotometer assay; urinary β2-M was detected by radioimmunoassay assay; urinary creatinine was detected by alkaline picric acid assay.[Results]1) Dietary intake of cadmium of population in cadmium contaminated area was1735.20mg, which was significantly higher than the control area value456.64mg. The urine cadmium level of population in cadmium contaminated area was significantly higher than that of control area value (P<0.01), while the urinary NAG level of population in the control area was higher than that of the contaminated area (P <0.01), and urinary β2-M between the two areas showed no significant difference (P>0.05).2) Dividing the subjects from contaminated area into five dietary cadmium groups, the statistical analysis results among the five groups showed that:at the same level of dietary cadmium intake, no significant gender difference was found in each urine index; and urine cadmium, urinary β2-M showed no age difference too (P>0.05), but the level of urinary NAG increased with age and the upward trend was significant (P <0.05).3) The statistical analysis results among the five dietary cadmium groups also showed that:urinary cadmium levels of population in contaminated area increased with the amounts of dietary cadmium intake (P<0.05), and this trend couldn’t be affected by gender or age factor; while urinary NAG, β2-M didn’t showed a similar trend. But the statistical analysis results among different urinary cadmium groups showed that:the urinary NAG, β2-M levels of population in contaminated area increased with urine cadmium (P<0.05), and this trend couldn’t be affected by gender or age factor too. 4) Dividing the subjects from contaminated area into different groups by dietary cadmium levels and village (because people from different villages showed different levels of cadmium exposure) respectively, and made the curves regression analysis among different groups. The results showed that:the relationship of urinary cadmium with dietary cadmium in different dietary cadmium groups or village groups was in the shape of letter "S"; but the fitting curves of urinary NAG, β2-M showed no meaningful trend..5) The results of univariate chi-square analysis and multivariate Logistic regression analysis showed that:in cadmium contaminated area, the level of dietary cadmium intake was a statistically significant factor for the abnormal rate of urine cadmium and urinary β2-M (P<0.05), i.e. the abnormal rate of urine cadmium and urinary β2-M increased with the level of dietary cadmium intake.[Conclusions]1) Dietary cadmium intake for a lifetime (75years) of population in contaminated area was that:male,2286.9mg; female,2015.Omg. The values were just above the WHO recommended threshold for health effects caused by cadmium exposure--2000mg. While compared to the other domestic cadmium polluted area, the situation of Hezhang cadmium pollution is not very serious.2) In the current level of environmental exposure to cadmium, urine cadmium, as the indicator of cadmium body load, increased with the amount of dietary cadmium exposure. But the population in the cadmium polluted area did not show significant renal injury.