New guidelines for tolerable daily intake of melamine

International experts have established a tolerable daily intake (TDI) for melamine, the chemical found recently in contaminated milk products. The TDI is the outcome of a meeting organized by WHO held this week in Ottawa, Canada. The TDI is lower than previous TDIs suggested for melamine by some national food safety authorities.

"We expect this could better guide the authorities in protecting the health of their public," said WHO Director for Food Safety, Dr Jørgen Schlundt, at the closing of the WHO expert meeting.

The international experts gathered by WHO have not set a "safe" level of melamine but they have established a "tolerable" level. Melamine is a contaminant that should not be in food. However, sometimes it is unavoidable. TDI represents the tolerable amount of unavoidable contaminant in food that a person can ingest on a daily basis without appreciable health risk. The TDI is meant to help national authorities set safe limits in food for withdrawal purposes should melamine be detected as a result of intentional adulteration.

The TDI for melamine has been established at 0.2 mg/kg body weight. Based on this, it leads a 50 kg person to a tolerable amount of 10 mg melamine per day.

The TDI applies to melamine alone. The TDI for cyanuric acid alone remains at 1.5 mg/kg body weight. Co-occurrence of melamine with cyanuric acid seems to be more toxic. However, adequate data are not available to allow the calculation of a health-based guidance value for this co-exposure.

"At the same time the limits for melamine in infant formula (1 part per million or ppm) and in other foods (2.5 ppm) introduced by many countries provide a sufficient margin of safety as compared to the TDI," added Dr Schlundt.

Twenty-one experts attended the meeting to review toxicological aspects of melamine and cyanuric acid.