The Association Between Low Concentration Of Cadmium Exposure And Kidney Function In The Chinese General Population

Part Ⅰ Establishment of the quantitative method for heavy metal cadmium in human urineObjective:Based on the method of Inductively Coupled Plasma Mass Spectrometry(ICP-MS),a rapid,sensitive and accurate method was developed for the determination of heavy metal cadmium in human urine samples.Method:In this study,Agilent 7900 inductively coupled plasma mass spectrometer was used to quantitatively detect cadmium and other heavy metals in human urine samples.The experiment was optimized and verified by referring to the national human biological testing project laboratory comparison plan.Results:The human biological samples in this experiment were tested by ICP-MS after strict pre-sample processing process.The results and raw data report forms are completed in a standard format.Pre-processing time for a single sample is about 2 min.The results of this experiment showed that the method quantitative limit(LLOQ)of cadmium was 0.3μg/L.Methods the detection limit was 0.08μg/L.The standard curve ranges from 0.10-5.00μg/L.The calibration curves showed good linearity(R~2>0.995).RSD is stable at 5-10%.Conclusion:In this experiment,ICP-MS detection method was used.This method has the advantages of simple and rapid sample pretreatment,high sensitivity,low quantitative limit,good stability,simultaneous analysis of polymetallic elements and wide linear range.It can meet the needs of large sample detection and provide a good basis for further epidemiological research.Part Ⅱ The association between low cadmium exposure and kidney function in the chinese general populationObjective:The aim of this part is to explore the association between low cadmium exposure and renal dysfunction.Method:This part of the study uses a cross-sectional study design.The study participants were residents who performed physical examination and screening at two social health centers in Shenzhen(Nanshan Social Health and Licheng Social Health)in 2018 and 2019.During the physical examination,the basic information and related information of the population were collected by using questionnaires and physical examinations,and urine samples and blood samples of the study population were collected at the same time.Inductively coupled plasma spectrometer(ICP-MS)was used to detect the heavy metal cadmium in urine samples.An automatic biochemical analyzer was used to measure renal function damage indicators such as MALB,NAG and AMG,and urinary creatinine level in urine samples.The glucose and lipid metabolism,lipid metabolism and other common indexes were measured by corresponding clinical methods.The basic characteristics of the study population were analyzed by chi-square test and variance analysis,and the correlation between urinary cadmium exposure and renal injury was analyzed by linear regression.The statistical method of the generalized additive model was used to make a graph,which intuitively showed the trend of the association between low urinary cadmium exposure and renal damage biomarkers after correcting confounding factors.Logistic regression method was used to calculate the OR value of glomerular damage in groups with different urinary cadmium concentrations.The trend study method was used to test whether there is a linear trend between the changes in urinary cadmium concentration and changes in renal injury-related indicators.Results:A total of 3 064 participants were included in this study.The average age(standard deviation)was 50(12.9),including 1152(38%)males and 1912(62%)females.The median(quartile interval)of the mean urinary cadmium exposure level in the population was<0.383μg/g Cr;0.383 to 0.639μg/g Cr;0.639 to 1.109μg/g Cr;>1.109μg/g Cr.Multivariate linear regression results show that after adjusting the confounding factors such as sex,age,BMI,smoking status,alcohol consumption,exercise habits and diseases history,the level of urinary cadmium was positively correlated with the level of renal injury marker.The regression coefficients were 0.153,0.104,and 0.187,and the differences were statistically significant(P<0.001).After grouping people with different levels of glomerular filtration rate,The risk of minor glomerular injury was higher in the group with high urinary cadmium levels than in the group with low urinary cadmium levels.The trend persisted after adjusting for multiple confounding factors.In addition,there was a significant correlation between urine cadmium concentration levels and glucose and lipid metabolism indicators(insulin,glycated hemoglobin,total cholesterol,high density lipoprotein cholesterol,and low density lipoprotein cholesterol)(P<0.05).Conclusion:The results of this study for the general community residents show that in low-dose cadmium exposed populations,human urine cadmium levels are significantly positively correlated with kidney function related indicators.The degree of renal damage may increase with the increase of urinary cadmium levels,suggesting that low levels of cadmium exposure may also cause kidney damage in the body.