Associations of lead biomarkers with renal function in Korean lead workers

Abstract

Aims: To compare associations of lead biomarkers with renal function in current and former lead workers. Methods: Cross sectional analysis of first year results from a longitudinal study of 803 lead workers and 135 controls in South Korea. Clinical renal function was assessed by blood urea nitrogen (BUN), serum creatinine, and measured and calculated creatinine clearance. Urinary N-acetyl-β-Dglucosaminidase (NAG) and retinol-binding protein were also measured. Results: Mean (SD) tibia lead, blood lead, and DMSA chelatable lead levels in lead workers were 37.2 (40.4) µg/g bone mineral, 32.0 (15.0) µg/dl, and 767.8 (862.1) µg/g creatinine, respectively. Higher lead measures were associated with worse renal function in 16/42 models. When influential outliers were removed, higher lead measures remained associated with worse renal function in nine models. An additional five associations were in the opposite direction. Effect modification by age was observed. In 3/16 models, associations between higher lead measures and worse clinical renal function in participants in the oldest age tertile were significantly different from associations in those in the youngest age tertile which were in the opposite direction. Mean urinary cadmium (CdU) was 1.1 µg/g creatinine (n = 191). Higher CdU levels were associated with higher NAG. Conclusions: These data suggest that lead has an adverse effect on renal function in the moderate dose range, particularly in older workers. Associations between higher lead measures and lower BUN and serum creatinine and higher creatinine clearances may represent lead induced hyperfiltration. Environmental cadmium may also have an adverse renal impact, at least on NAG.

Associations of Patella Lead and Other Lead Biomarkers With Renal Function in Lead Workers

“…However, associations for the three lead biomarkers obtained in the first evaluation are likely to be the most valid because the number of study participants was greater. A comparison of associations of patella lead with renal outcomes from the third evaluation to associations of blood, tibia, and DMSA-chelatable lead with renal outcomes from the first evaluation (conducted a mean of 2.2 years earlier in the original cohort of 803 lead workers 3 ) reveals consistent findings. Higher blood and tibia lead levels were associated with decreased renal function in those workers whose ages were in the oldest tertile; beta coefficients were in the opposite direction in the youngest age group for the clinical outcomes but not for NAG.…”

“…3,4 In brief, blood lead was measured with an Hitachi 8100 Zeeman backgroundcorrected atomic absorption spectrophotometer (Hitachi Ltd. Instruments, Tokyo, Japan) 5 at the Institute of Industrial Medicine, a certified reference laboratory for lead in South Korea. Patella and tibia lead levels were assessed via a 30-minute measurement of the left medial patella and midtibia diaphysis, respectively, using 109 Cd in a back-scatter geometry to fluoresce the K-shell x-rays of lead.…”

“…As previously described, 3,4 workers were recruited from 26 plants that 1) produced lead batteries, lead oxide, lead crystal, or radiators or 2) were secondary lead smelters. Workers were designated as lead workers based on the potential for exposure to lead in the manufacturing process.…”

“…3,4 Pertinent data and biologic specimens collected included a standardized questionnaire on demographics, medical history, and occupational history; blood pressure, height and weight measurements; a blood specimen (for blood lead, BUN, and serum creatinine), a spot urine sample (for NAG, RBP, and creatinine), and a patella lead measurement. Tibia lead, obtained in the second evaluation, was available for the subset of workers (n ϭ 574) who participated in both the second and third evaluations.…”

“…3 We studied a range of renal outcomes, including clinical (blood urea nitrogen [BUN], serum creatinine, measured and calculated creatinine clearances) and early biological effect (N-acetyl-␤-D-glucosaminidase [NAG] and retinolbinding protein [RBP]) measures. Lead biomarkers included tibia, blood, and dimercaptosuccinic acid (DMSA)-chelatable lead.…”