Ambient Melamine Exposure and Urinary Biomarkers of Early Renal Injury

Abstract

Information about environmental exposure to melamine and renal injury in adults is lacking. We investigated this relationship in 44 workers at two melamine tableware manufacturing factories in Taiwan (16 manufacturers, eight grinders, ten packers, and ten administrators) and 105 nonexposed workers (controls) at one shipbuilding company who were enrolled in August-December of 2012. For melamine workers, personal and area air samples were obtained at the worksite over 1 workweek (Monday-Friday). In the same week, pre-and post-shift one-spot urine samples were collected each workday and one first-spot urine sample was collected on each weekend morning and the following Monday morning. For each control, a one-spot urine sample was collected on Friday morning. A blood sample was also obtained from each participant at this time. Melamine levels were measured in air, urine, and serum, and early renal injury biomarkers were measured in urine. Urinary melamine concentrations in manufacturers increased sharply between pre-and post-shift measurements on Monday, remained significantly elevated throughout the workweek, and decreased over the weekend; changes in urinary melamine concentrations were substantially lower for other melamine workers. Manufacturers were exposed to the highest concentrations of ambient melamine and had significantly higher urinary and serum melamine concentrations than did the controls (P,0.001). Urinary melamine levels were positively associated with urinary N-acetyl b-D-glucosaminidase (NAG) levels but not microalbumin levels, and the detectable b2-microglobulin rate increased in the manufacturers group. In conclusion, ambient melamine exposure may increase the levels of urinary biomarkers of renal tubular injury in this occupational setting.

Development of analytical method of melamine in placenta from pregnant women by isotope‐dilution liquid chromatography/tandem mass spectrometry

“…Multiple reaction monitoring (MRM) mode was used. The characteristic fragmentation transitions m/z 127 > 85 for melamine and m/z 133 > 89 for the IS were used for quantification and m/z 127 > 68 for melamine was used for quantitative confirmation analysis with the dwell time set at 100 ms, and unit resolution (Figure ). Figures A and B show signals of ion chromatograms for placenta unfortified with the melamine standard and fortified with 100 ng/mL of melamine standard, respectively.…”

“…Previously, we established an analytical method for measuring melamine in urine and serum samples . In the first stage of the current study, we modified our previous procedure for measuring serum melamine to measure melamine in maternal serum in the third trimester and umbilical cord serum on date of delivery to determine whether maternal melamine exposure correlated with melamine levels in their infants. In the second stage, we established an analytical method for measuring melamine in the placenta.…”

“…Maternal serum and umbilical cord serum were measured and modified using solid‐phase extraction (SPE) and isotope‐dilution liquid chromatography/tandem mass spectrometry (LC/MS/MS) as described previously . Briefly, 300 μL of serum sample was added to 13 C 3 15 N 3 ‐melamine‐labeled solution as an internal standard (IS) and mixed with 900 μL 2% phosphoric acid; which was centrifuged in a glass tube at 3500 rpm for 10 min to remove proteins from the serum.…”

“…Briefly, 300 μL of serum sample was added to 13 C 3 15 N 3 ‐melamine‐labeled solution as an internal standard (IS) and mixed with 900 μL 2% phosphoric acid; which was centrifuged in a glass tube at 3500 rpm for 10 min to remove proteins from the serum. This was followed by SPE …”

“…Several research groups studying long‐term low‐dose melamine exposure have suggested that melamine‐induced oxidative stress and inflammation play pathological roles in renal injury . Epidemiological studies have also associated melamine exposure and early renal injury markers in children and occupational workers …”