| Objective: As one of the major excretory and toxic target organs of lead,a study showed that,there were pathological and functional changes on kidney with blood lead ?100?g/L and lead exposure ?1 year.Thus,to study the early renal damages in chronic lead exposure at low dose,and screen the early renal damage markers,may be important to early detection,early diagnosis,and early treatment.Methods:1 All the staffs of storage battery factory were selected,and the subjects occupational exposure to lead were assigned to the lead exposure group,and others were assigned to the control group.2 The informations of general characteristics,history of occupational lead exposure,personal habits,diseases history were surveyed by the self-designed questionnaire.3 Blood and urine samples were collected in the morning before work and breakfast,and the urine samples should be centrifuged.Otherwise,the samples should be storaged at-20 ? in time.All the process must be subjected to the consent.4 The lead concentrations in blood and urine samples were detected by graphite furnace atomic absorption spectrometry.Blood uric acid?BUA?was detected by uric acid enzymatic.Blood urea nitrogen?BUN?was detected by urea enzyme-glutamate dehydrogenase enzymes.Serum creatinine?Scr?was detected by enzymatic method.Urine creatinine?Ucr?was detected by picric acid method.Urinary beta 2-microglobulin?U?2-MG?was detected by latex enhanced immune turbidimetric method.And urinary n-acetyl-beta-D-amino glycosidase enzymes?UNAG?was detected by ELISA.5 All data were used Epidata 3.1 software to establish the database,andanalyzed by SPSS 21.0 software.The benchmark dose?BMD?and the lower confidence limit of benchmark dose?BMDL?were calculated by the benchmark dose software.Results:1 In this survey,486 subjects were included,370 cases were lead exposure group and 166 cases were control group?male: 309 cases,female:177 cases?.The age ranged from 18 to 53 years old,and the duration of occupational exposure to lead was between 1 month and 34.5 years.The percents of blood lead?400?g/L and urinary lead?70?g/L accounted for16.05% and 3.29%,respecttively.2 The levels of BUA,BUN,blood lead and urinary lead in lead exposure group were higher than those in control group?P<0.05?.But there were no differences between the lead exposure group and control group in the levels of Scr,Ucr,U?2-MG and UNAG?P >0.05?.3 There were three groups according to working years occupationally exposed to lead: the control group, 5 years group and > 5 years group.The concentrations of blood lead,urinary lead,Scr,U?2-MG and UNAG had deferences in the three groups?P?0.05?.Compared to the control group,the levels of blood lead,urinary lead,BUN and UNAG were different in 5 years group?P<0.05?,the levels of blood lead,urinary lead,BUA,BUN,Scr and UNAG were different in > 5 years group?P<0.05?.The levels of blood lead,urinary lead,Ucr,U?2-MG and UNAG were different between 5 years group and > 5 years group?P<0.05?.4 There were four groups according to the level of blood lead: 100.65,215.56,342.30 and >342.30 group.Among the four groups,the levels of Scr and U?2-MG showed no differences?P>0.05?,the levels of BUA,BUN,Ucr and UNAG had differences?P?0.05?.The level of UNAG changed when blood lead >100.65 ?g/L?P<0.05?,the levels of BUA and Scr changed when blood lead >215.56 ?g/L?P<0.05?,the levels of BUN and Ucr changed when blood lead >342.30 ?g/L?P<0.05?.5 There were four groups according to the level of urinary lead:6.63,14.05,30.33 and >30.33 group.Results showed that among the four groups,the levels of BUA and Ucr had no differences?P>0.05?,the levels of BUN,Scr,U?2-MG and UNAG were different?P<0.05?.When urinary lead>6.63?g/L,only the level of Scr changed?P<0.05?,when urinary lead>14.05 ?g/L,the level of BUA changed?P<0.05?,when urinary lead>30.33 ?g/L,the levels of BUN,Ucr,U?2-MG and UNAG changed?P<0.05?.6 The levels of BUA,BUN,Scr and UNAG showed positive correlations with blood lead level?P<0.05?,and the levels of BUN,U?2-MG and UNAG were positively correlated with urinary lead level?P<0.05?.There was no correlation between the levels of Ucr and blood lead or urinary lead level?P>0.05?.7 The gender,age,smoking,drinking and dyehair may affect the lead levels in the body.Multiple linear regression analysis showed that there had no factors entered the regression analysis of U?2-MG and UNAG.8 The analysis of trend chi-square showed that the abnormalities of BUA,BUN,U?2-MG and UNAG were increased with the increasing of blood lead level?P<0.05?,and there was no trend between the abnormalities of Scr and Ucr and blood lead level?P>0.05?.U?2-MG and UNAG abnormalities increased along with the increase of urinary lead level?P<0.05?,while there was no trend between the abnormalities of BUA,BUN,Scr and Ucr and blood lead level?P>0.05?.9 According to the markers of the renal function,blood lead and urinary lead,the values of BMD/BMDL were calculated by different models.Only the BUA,BUN,U?2-MG and UNAG entered the program.The model was the optimal as AIC value was the smaller and P>0.05.BMD/BMDL was calculated by LogProbit model and Logistics model.According to the order of BUA,BUN,U?2-MG and UNAG,the BMD/BMDL of blood lead were676.66/443.95?g/L,512.34/414.10?g/L,130.40/100.98?g/L,602.78/431.84?g/L,the BMD/BMDL of urinary lead were 199.28/66.30?g/L,54.10/43.68?g/L,77.02/47.80?g/L,20.29/ 18.05?g/L,which showed the BMD andBMDL on UNAG were the lowest.Conclusions:1 Occupational lead exposure may cause kidney damage which was increased gradually when the lead levels in the body was increased.2 Multiple linear regression analysis showed that U?2-MG and UNAG were not affected by such factors: age,gender and so on,and the result was stable and representative.3 UNAG can be used as a sensitive indicator for renal damage of occupational lead exposure. |
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