| Cadmium(Cd)is one of the most toxic non-essential heavy metal element.Cadmium can accumulate in organs such as kidneys and liver for a long time when enter human body.Long-term exposure to low doses of cadmium can cause damage to organs and tissues such as the kidneys,liver,and bones.Rice has a strong bio-concentration effect on cadmium.China is a huge producer and consumer of rice.With the increase of cadmium pollution in recent years,rice have become a major source of dietary cadmium exposure for Chinese population.Dietary cadmium exposure is the most important source of environmental cadmium exposure for non-professional population.Long-term consumption of rice which concentration of cadmium exceeded can cause health damage for people.At present,the research on monitoring indicators and standards for environmental cadmium pollution is lagging behind in domestic,which is disadvantage to the government’s monitoring of cadmium pollution and health status of residents.Therefore,in order to reduce cadmium exposure level and protect the health of the population,it becames quite important to investigate and research the status of cadmium pollution and its impact on people’s health.We collected the morning urine of the sample population and the rice they eat,and the association between urinary cadmium(UCd)concentration and indicators of renal dysfunction,including urinary N-acetyl-β-Dglucosaminidase(UNAG)and urinary P2-Microglobulin(Uβ2MG)were investigated in 290 inhabitants≥50 years of age(132 males and 158 females)in three typical cadmium-contaminated rural areas in china(include Shaoguan,Guangdong province;Hezhang,Guizhou province;Gejiu,Yunnan province).The association between the UCd,urinary NAG and urinary β2MG were explored by regression analysis and chi-square test to make comprehensive assement the influence of cadmium on general population’s health.In the present study,the threshold levels of urinary cadmium were estimated as the benchmark dose(BMD)and its lower limit(BMDL)using the benchmark dose approach.The cadmium concentration in rice was examined.The EMI and THQ of cadmium in rice were investigated to assess the risk of dietary cadmium exposure.The main findings of this project are as follows:1.The urinary cadmium and its health effects indicators research.The cadmium exposure levels in Hezhang and Gejiu districts are higher than Shaoguan.Populations are exposed to a high degree of cadmium exposure risk,and have already suffered a certain degree of renal function damage.Urinary cadmium has a greater impact on urinary NAG and urinary β2MG.Urinary Cd have a significant positive relationship with urinary NAG andβ2MG levels,and urine β2MG was more significant than urinary NAG.2.Benchmark dose and benchmark dose low of urinary cadmium.Set additional risk value at 10%.When using urinary NAG as index,BMD/BMDL of UCd were 6.19/5.32μg/g cr for male,and were 4.40/3.3 μg/g cr for female.When using urinary β2MG as an index,the BMD/BMDL of UCd were 1.97/1.18 μg/g cr for male,and were 1.73/1.28 μg/g cr for female.The BMD/BMDL were 5.45/4.81 μg/g cr for urinary NAG and were 2.20/1.72 μg/g cr for urinary P2MG.Under the same reaction conditions,BMD/BMDL of UCd for P2MG was lower than BMD/BMDL for NAG.This shows that urinary P2MG as an effect indicator of environmental cadmium pollution for kidney dysfunction is more sensitive than urinaryNAG.The BMDL for urinary β2MG is generally lower than the exposure limit of cadmium in domestic for occupational.Therefore,in order to protect health of population,we recommend that appropriately reduce the standard of cadmium exposure and establishe the standard for general population.3.Cadmium concentration in rice and health effects.The geometric mean of cadmium concentration in rice was 0.139 mg/kg,and the over-standard rate of cadmium content in rice was all over 20%in different regions.The geometric mean of EMI in rice was 26.99μg/(month·kg bw),and the geometric mean of THQ was 1.08.There was a difference in EMI and THQ and have different over-standard phenomenon.This indicates that the cadmium exposure in the survey area is relatively high,and the cadmium intake of residents through the consumption of local rice is relatively high.Cadmium exposure of rice have a greater health risk to the human body.Cadmium concentration in rice have a significant correlation with urinary NAG and urinary P2MG,and urine NAG and urinaryβ2MG levels increased significantly with the increase of cadmium concentration in rice. |
