In a small dietary intervention study published in the peer-reviewed Journal of the American Medical Association JAMA Internal Medicine, researchers from Taiwan found the consumption of hot soup from plastic melamine-formaldehyde-resin bowls to increase urinary melamine levels of test persons (Wu et al. 2013).
The researchers hypothesized that melamine would migrate from melamine table ware and be ingested by the test persons, leading to a higher body burden of melamine. They separated a total of 12 people (6 men/6 women) into 2 groups and gave them hot soup to eat, either from a plastic melamine bowl or from a ceramic bowl. Urine samples were taken before and during 12 hours after the meal. Three weeks later the experiment was repeated, but this time the group previously eating soup from melamine plastic bowls now ate their soup from ceramic and vice versa.
Urinary melamine levels were statistically significantly increased in participants eating from melamine plastic table ware up to 12 hours later (total average melamine excretion: 8.35 µg) compared to the other group (total average melamine excretion: 1.31 µg; detection limit 0.8 µg/L). These findings suggest that melamine migrated from the table ware to the hot food. Interestingly, 2/3 of the control group also excreted detectable levels of melamine.
Melamine is used in food contact plastics as monomer and as stabilizing additive. Melamine is not only used in plastic table ware, but also in other food contact applications like coatings, adhesives, and in paper/paperboard products. Current regulations in the EU and USA allow migration of melamine from food contact materials at 2.5 mg/kg food.
The illegal practice of deliberate melamine addition at high levels to diluted milk led to mass poisoning of Chinese infants in 2008, with several children dying and many suffering from kidney stones or renal failure. It has been hypothesized that chronic exposure to low levels of melamine may lead to the formation of kidney stones in adults, but further research is needed (Liu et al. 2011).
Wu, C., et al. (2013). “A crossover study of noodle soup consumption in melamine bowls and total melamine excretion in urine.” JAMA Internal Medicine: 1-2.
Liu, C.-C., et al. (2011). “Low exposure to melamine increases the risk of urolithiasis in adults.” Kidney International 80(7): 746-752.
EFSA Scientific Opinion on Melamine in Food and Feed, European Food Safety Authority, EFSA Journal 2010, 13 April 2010
FDA Melamine in Tableware: Questions and Answers, US Food and Drug Administration FDA, 27 January 2011
Plastic plates and kidney stones claim “overcooked”. Behind The Headlines, NHS 23 January 2013
Could Chemical in Dishware Raise Your Risk for Kidney Stones? Health Day News, 21 January 2013