select search filters
briefings
roundups & rapid reactions
Fiona fox's blog
A study comparing soup consumption in melamine bowls and total melamine excretion in urine found that a continuous low-dose of melamine exposure may be associated with urinary system stones in children and adults, according to JAMA Internal Medicine.
Prof Sir Colin Berry, Emeritus Professor of Pathology, Queen Mary University of London, said:
“This study has a good experimental design and shows very small amounts of melamine excreted, as expected. As the authors point out, no comments can be made about effects but at low levels of melamine you would not expect toxicity. The ‘follow-up’ paper would be to see if those who used melamine always have more stones than those who don’t. But you would need huge numbers to carry this out so I am not sure it could be done. The findings of the current study are, in my view, noise of no clinical significance.”
Professor Alan Boobis, Professor of Biochemical Pharmacology at Imperial College London, said, said:
“Melamine is a well studied compound. Its primary toxic effect is to the kidney. The effect is highly dependent on the dose, as it is a consequence of crystallisation of melamine. At doses below those which produce sufficient amounts in the urine to crystallise there is no adverse effect. Hence, exposure to small amounts of melamine will not cause any harm. According to EFSA and the WHO, regular exposure to melamine in amounts of up to 0.2 mg per kg body weight in the diet on a daily basis (the tolerable daily intake) would not be expected to cause any harm. Indeed, it has been known for some time that consumers can be exposed to small amounts of melamine through the use of melamine cookware and this does not result in excedence of the tolerable daily intake.
“EFSA evaluated a number of use scenarios of melamine cookware and concluded that none resulted in levels that would exceed the tolerable daily intake. This is confirmed in the study by Wu et al. Total excretion of melamine (almost all of which when ingested will be excreted in the urine) was maximally around 0.02 mg. Given that the tolerable daily intake is 0.2 mg/kg bw, equivalent to 14 mg per 70 kg adult or 2.4 mg per 12 kg toddler (1-3 years of age), one would have to consume very many portions (>200 by a toddler) of food cooked as in the Wu et all study in a single day before the tolerable daily intake was exceeded.”
Professor Tony Dayan, Emeritus Professor of Toxicology, University of London, said:
“1. Melamine is a monomer that is polymerised in the manufacture of resins used to make bowls and other containers for domestic use. Similar resins occur in other food containers and in adhesives used to seal and label various food packs. It may also occur in foodstuffs as a metabolite of a pesticide.
“Its biological and toxicological properties have been extensively studied, even before the contaminated milk and animal food scandal a few years ago.
“2. Major regulatory agencies, such as WHO [see WHO below], the US FDA and the European EFSA have published formal reviews of its toxicity from which various estimates have been derived of the ‘Tolerable Daily Intake’ (TDI) in man considered not to represent any risk to consumers.
“The estimates have ranged from 0.63 to 0.2mg/kg/d for adults. The potential toxicity of the association in foodstuffs of melamine and the related substance cyanuric acid is included in these estimates.
“The principal risk, as shown in the recent contaminated milk scandal is the formation of kidney and bladder stones if sufficient melamine is ingested regularly for months on end.
“3. The new report from Taiwan continues work started there some time ago showing that melamine may be leached from containers holding hot, acid liquids, such as certain types of soup.
“4. The new report suggests that the intake of melamine from 500mL hot soup in melamine resin bowls may result in the urinary excretion of melamine up to 8.35μg/day. When the subjects ate the soup from ceramic bowls they excreted melamine 1.31μg/day. Urinary excretion of melamine is a reasonable indicator of the total amount ingested by the person.
“5. The new research was done because of concern about the high incidence of such stones in Taiwan and their possible relationship to melamine in the diet.
“6. Conclusion: Much has still to be done to quantify the frequency and the concentration of melamine monomer in the diet in every country and its relationship to the quantity excreted in the urine but the amounts now demonstrated seem small in relation to what is generally accepted as a tolerable daily dose.
“The new information does not suggest a major new risk factor in the causation of kidney and bladder stones particularly when the very varied nature of the foodstuffs likely to be stored and served in melamine resin bowls are considered many of which will probably not leach any of the monomer from the resin or adhesive.”
‘A crossover study of noodle soup consumption in melamine bowls and total melamine excretion in urine’ by Chia-Fang Wu et al., published in JAMA Internal Medicine on Monday 21st January.