Search

Melamine and phthalate, mainly di-(2-ethylhexyl) phthalate (DEHP), are ubiquitously present in the general environment. We investigated whether urine melamine levels can modify the relationship between DEHP exposure and markers of early renal damage in children. A nationwide health survey for Children aged ≤12 years possibly exposed to phthalates were enrolled between August 2012 and January 2013. They were administered questionnaires to collect details regarding past DEHP exposure to phthalate-tainted foodstuffs. Urine samples were measured melamine levels, phthalate metabolites and biomarkers of renal damage, including urine microalbumin/creatinine ratio (ACR), N-acetyl-beta-d-glucosaminidase (NAG), and β2-microglobulin. The study included 224 children who had a median urine melamine level (μg/mmol creatinine) of 1.61 ranging 0.18-47.42. Positive correlations were found between urine melamine levels and urine ACR as well as urine NAG levels (both Spearman correlation coefficients r = 0.24, n = 224, p < .001). The higher the past DEHP exposure or urine melamine levels, the higher the prevalence of microalbuminuria. An interaction effect was also found between urine melamine levels and past DEHP exposure on urine ACR. Melamine levels may further modify the effect of past DEHP exposure on urine ACR in children., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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 β-d-glucosaminidase (NAG) levels but not microalbumin levels, and the detectable β2-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., (Copyright © 2015 by the American Society of Nephrology.)

This study aims to examine whether behavior intervention can decrease total urinary melamine excretion. A total of 16 healthy subjects were recruited from two university buildings (eight subjects each). By using a stepped-wedge cluster randomized and controlled trial design, we randomly assigned eight subjects from the same building to the serial steps of either control-intervention-intervention or control-control-intervention. Each step lasted for 3 days. Subjects in the intervention step carried one bag containing stainless steel tableware as meal boxes and used them for each meal during the trial, whereas those in the control step carried one empty bag. The 24 h urine samples for 9 consecutive days were collected. In the control-intervention-intervention group, after excluding two subjects with missing data, the median absolute difference of the total 3 day melamine excretion between the seventh to the ninth day and from the first to the third day was -19.9 μg (a range from -160.6 to -7.2 μg, p = 0.028, n = 6). The median protection percent of the total 3 day melamine exposure (the amount from the seventh to the ninth day minus the amount from the first to the third day, divided by the amount from the first to the third day) was 68.4%, ranging from 41.8% to 91.8%. Regular use of stainless steel-made meals boxes can mitigate melamine exposure from melamine tableware.

Background: We investigated whether melamine concentrations in 1-spot overnight urine sample can represent the previous 8- and 24-h total urinary melamine excretions in school children. The relationship between urinary melamine levels and several clinical biomarkers of early renal injury such as microalbumin and N-acetyl-beta-D-glucosaminidase (NAG) in urine was also examined., Methods: School children, aged 6-10 y, and their parents who were healthy and lived closely to Kaohsiung Medical University-affiliated hospitals were recruited. All study children had the first 1-spot overnight urine sample collected on the Sunday morning (the first day) immediately when they woke up, and then all the subsequent urine samples continued to be collected until the first 1-spot overnight urine sample on the morning of the next day (Monday, the second day). Two first 1-spot overnight urine samples from their parents on the same Sunday and Monday mornings were also collected. This protocol was completed in the July and August of 2011. All urine samples were measured for melamine, biomarkers of early renal injury, and creatinine., Results: There were 7 girls and 16 boys in this study. Except for one missing urine sample from 1-spot overnight urine sample on the morning of the second day, melamine levels in the rest of urine samples among the study children were all detectable. The median melamine levels of 1-spot overnight urine samples on the first and second day mornings were 0.93 and 1.73 μg/mmol of creatinine respectively. We found that melamine concentrations of 1-spot overnight urine samples on the second day morning were highly correlated with the previous 8- and 24-h total melamine excretions in urine (r=0.936, p<0.001, n=21 and r=0.616, p<0.001, n=21 respectively). Good correlation of 1-spot overnight urine sample on the first and second day mornings was also found (r=0.619, p=0.003, n=21). In contrast, there were no significant correlations of 24-h total urinary melamine and 24-h total urinary microalbumin and NAG excretions (r=-0.221, p=0.319, n=22 and r=0.084, p=0.710, n=22)., Conclusion: Melamine levels in 1-spot overnight urine sample can predict the previous 8- and 24-h total melamine excretions in urine. Since melamine exposure levels in these school children were relatively low, its association with clinical biomarkers of early renal injury was not found. A future study is necessary to increase the sample size and to find the more sensitive preclinical biomarkers of renal injury to link with low melamine exposure in children in the community., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: The link between melamine-contaminated daily foodstuffs and urolithiasis formation has drawn an international concern. However, detection of melamine levels in urine may not completely represent external melamine exposure. Thus, finding an additional analytical method for the study of environmental melamine exposure and its adverse effect in humans is crucial., Methods: Eleven adult patients diagnosed with uric acid urolithiasis were retrospectively analyzed. Melamine levels in their overnight one-spot urine samples were measured by a triple quadrupole liquid chromatography tandem mass spectrometry (LC-MS/MS). The compositions of stone samples were analyzed by the Fourier transform infrared (FTIR) spectrophotometer and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)., Results: Seven (63.6%) out of 11 patients had detectable melamine levels in their urine specimens (method of detection limit: 0.8 ng/ml). Three patients (27.3%) were highly suspected of having melamine-containing urolithiasis in FTIR spectra. In one of those three cases who still had available stored stone specimens, MALDI-TOF MS further confirmed melamine components in this male patient's stone specimens. In contrast, his urinary melamine level was below the detection limit by LC-MS/MS., Conclusions: Direct analysis of melamine in the composition of urolithiasis by MALDI-TOF MS can be an additional analytical method to evaluate for external melamine exposure., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Melamine, a widely used chemical found in many products in daily use, became a public health concern due to melamine-associated urinary stone formation in children. In adults, it is still unknown whether low-dose melamine exposure may also cause urolithiasis. To address this question, we studied 211 Taiwanese patients diagnosed with calcium urolithiasis and 211 age- and gender-matched controls. All patients completed a detailed questionnaire and provided blood and urine samples for biochemical analysis. Urinary melamine concentrations were measured by triple-quadrupole liquid chromatography tandem mass spectrometry. Compared with those whose urinary melamine levels were below the detection limit of the method, patients with urinary melamine levels of up to 3.11  ng/ml and those with levels of ≥3.12  ng/ml had 3.01- and 7.64-fold increased risk, respectively, of calcium urolithiasis after adjusting for educational level, fluid intake, cigarette smoking, betel quid chewing, alcohol drinking, urinary uric acid, calcium, creatinine, and estimated creatinine clearance rate. The population attributable risk of calcium urolithiasis averaged 50% when melamine was detected in the urine, after considering other covariates. MALDI-TOF mass spectrometry detected melamine in the stones of nine representative patients who had measurable urinary melamine levels. Thus, low-dose melamine exposure can play an important role in calcium urolithiasis in Taiwanese adults.

Melamine is commonly used to manufacture tableware, and this could be one of the important exposure sources in humans. The study aims to measure melamine migrated from different material-made tableware by the most sensitive technique of liquid chromatography-tandem mass spectrometry (LC-MS/MS). The test samples were filled with pre-warmed designated-temperature (from room temperature (∼20 °C), 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, to 90 °C) simulant (either distilled water or 3% acetic acid) up to 20 ml and immersed in a water bath at that designated temperature for 15 or 30 minutes (min). High melamine migration levels, ranging from 6.97 to 19.03 μg/ml, can be measured from all melamine-made samples containing 20 ml 3% acetic acid in water bath of 90 °C for 30 min, whereas melamine cannot be detectable in all other material-made samples in the same condition. In addition, the cheaper the melamine-made tableware samples, the higher the melamine migration levels. The migration of melamine amount is dependent on different temperatures, contact times, simulant, and prices of tableware. Since tableware is used in daily life, it is prudent to cautiously select materials that contain foodstuffs., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)

Background: This study aims to investigate the association between urinary melamine concentration and the risk of urolithiasis in adult., Methods: From 2003 to 2007, 11 and 22 patients diagnosed with upper urinary tract uric acid urolithiasis and calcium urolithiasis, respectively, were recruited from Kaohsiung Medical University Hospital. For comparison, we randomly collected 22 sex- and age-matched subjects who come to the same hospital for regular health check-up at the same period of time. Urinary melamine concentration was measured by the method of triple-quadrupole liquid chromatography tandem mass spectrometry (LC-MS/MS). Wilcoxon rank sum test was used to compare the urinary melamine concentrations in uric acid urolithiasis patients with controls as well as in calcium urolithiasis patients with controls. FDR (false discovery rate) was used to correct the p-values for two comparisons., Results: Subjects with uric acid urolithiasis (median: 0.50 vs 0.06microg/mmol creatinine, Wilcoxon test: FDR&#95;p=0.024) and with calcium urolithiasis (median: 0.14 vs 0.06, FDR&#95;p=0.024) had significantly higher urinary melamine concentration than controls. Based on the ROC curves, subjects whose melamine levels were over 0.262 and 0.037microg/mmol creatinine, respectively, might have significant risks to have uric acid and calcium urolithiasis., Conclusion: This preliminary study suggests that exposure to even low-dose melamine-related products still have the potential to develop both uric acid and calcium urolithiasis in adults., (Copyright 2009 Elsevier B.V. All rights reserved.)