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 theworksite over 1 workweek (Monday-Friday). In the sameweek, pre- and post-shift one-spot urine samples were collected eachworkday and one first-spot urine sample was collected on each weekendmorning and the followingMondaymorning. For each control, a one-spot urine sample was collected on Fridaymorning. 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 onMonday, remained significantly elevated throughout the workweek, and decreased over the weekend; changes in urinary melamine concentrations were substantially lower for other melamine workers. Manufacturerswere exposed to the highest concentrations of ambientmelamine and had significantly higher urinary and serum melamine concentrations than did the controls (P<0.001). Urinary melamine levels were positively associated with urinaryN-acetyl b-D-glucosaminidase (NAG) levels but notmicroalbumin levels, and the detectable b2-microglobulin rate increased in themanufacturers group. In conclusion, ambient melamine exposure may increase the levels of urinary biomarkers of renal tubular injury in this occupational setting.