Effect of Cumulative Blood Lead and Cumulative Blood ZPP as Lead Body Burden on Renal Lead Biomarkers

Yoon, Gang Ho; Kim, Nam Soo; Kim, Jin Ho; Kim, Hwa Sung; Lee, Byung Kook

Abstract

OBJECTIVE
To evaluate the possibility of cumulative blood lead and blood ZPP as surrogates of lead body burden and to investigate their association with renal function as an index of lead body burden.
METHODS
The study subjects comprised 678 lead workers with past blood lead and blood ZPP data from their employment. Cumulative blood and ZPP were calculated by accumulating the every year mean value of both indices from the new employment since 1983. To assess the cumulative data of lead workers who started their lead work before 1983, the years before 1983 were simulated with the first available data from 1983. Study variables for lead body burden were tibia bone lead and DMSA chelatable lead, whereas those for current lead biomarkers were blood lead and blood ZPP. BUN and serum creatinine were selected as clinical renal biomarkers, while NAG (N-acetyl-D-glucosamine) and RBP (Retinol binding protein) were selected as early renal biomarkers.
RESULTS
The association between cumulative blood lead and blood ZPP with tibia bone lead was statistically significant with determinant coefficients (r(2)) of 0.72 and 0.567, respectively, and their relationships were better explained by the curvilinear regression model. In multiple regression analysis of current lead biomarkers on the renal biomarkers after controlling for possible confounders (age, sex, job duration, smoking and drinking status), blood lead was associated only with log-transformed NAG, whereas blood ZPP was associated with 3 other renal biomarkers. On the other hand, in multiple regression analysis of biomarkers of lead body burden on renal biomarkers after controlling for possible confounders (age, sex, job duration, smoking and drinking status), cumulative blood ZPP and tibia bone lead were associated with all 4 renal function biomarkers, whereas cumulative blood lead and DMSA chelatable lead were associated with 3 renal biomarkers except BUN.
CONCLUSION
Cumulative blood and ZPP were demonstrated to be good surrogates of lead burden. Furthermore, the cumulative blood ZPP was confirmed to have a better association than the cumulative blood lead.