A study published in the KeAi journal Environmental Chemistry and Ecotoxicology has found that serving high-temperature liquids or foods in melamine bowls causes melamine – a kidney toxicant – to leach into the bowl’s contents at a rate 3 times higher* than the European Food Safety Authority’s daily intake recommendation for newborn infants.
IMAGE: Melamine bowls on sale in a supermarket. Image copyright - Kurunthachalam Kannan
Melamine is widely approved for use in the manufacturing of a number of items, including some cooking utensils and tableware – its use is particularly common in East Asia. In 2008, it was found in infant formula in China, resulting in 300,000 infants and young children experiencing kidney and urinary tract effects, including kidney stones, with six reported deaths. At that time, traces of melamine were also detected in milk and other food products. However, according to one of the authors of this study, Prof. Kurunthachalam Kannan, there has been little research into the potential of melamine to leach from tableware: “A few earlier studies have focused on whether putting harsh products, such as acid, in a melamine container might release melamine, however, they did not mimic real world conditions. Our experiment recreated an everyday situation.”
For their study, Prof. Kannan and his colleagues at New York University School of Medicine bought four brands of melamine bowls from supermarkets in Japan and the US. They swirled 30 ml of hot water (90-100°C) in each of the bowls for 15 seconds, then analysed the water for signs of melamine. This leaching test was repeated 32 times.
They found that the concentrations of melamine leaching into hot water (adjusted to take into account variations in bowl sizes) were in the range of 0.37 – 70.2 ng/cm2, and were still present at the 32nd attempt (0.09 - 15.7 ng/cm2). They also noted that the greater the surface area the bowl’s contents touched, the more melamine leached. Importantly, they found that while the levels of melamine leached were safe for most age groups, in the case of newborn babies, if melamine bowls were used for the preparation of their infant formula, they could potentially ingest melamine at levels of up to 620 µg/kg bw/day – 3 times* higher than the European Food Safety Authority’s tolerable daily intake recommendation for that age group.
Prof. Kannan admitted: “My colleagues and I were surprised by the results. We had not expected to find melamine being leached after the first few rinses. But we found leaching at the 32nd rinse cycle; the maximum number we used in the study.”
He added: “Based on these results, we would not recommend using melamine bowls for preparing hot foods, acidic foods or children’s dishes.”
* At the time of the study, the amount of melamine absorbed by the bowls’ contents was 1.2 times higher than the EFSA tolerable daily intake limit, which has since been lowered.
Contact the paper’s corresponding author: Kurunthachalam Kannan, Kurunthachalam.firstname.lastname@example.org
Tazazawa, M., Suzuki, S. and Kannan, K. (2020). Leaching of melamine and cyanuric acid from melamine-based tableware at different temperatures and water-based simulants. Environmental Chemistry and Ecotoxicology, 2, 91-96.