Scientific Opinion on the food additive E 239

Hexamethylene tetramine (HMT) is a food additive, currently only permitted in the EU for use in Provolone cheese. The maximum permitted level is 25 mg/kg residual amount, expressed as formaldehyde, the breakdown product of HMT under acidic conditions.

HMT has been previously evaluated by the Joint Expert Committee on Food Additives (JECFA, 1974), which established an ADI of 0.15 mg/kg bw/day based on a reproductive study with a NOEL of 15 mg/kg bw/day. Due to limitations in the database, the Panel could not identify a critical study and therefore could not derive a new ADI.

However, the Panel noted that the exposure to formaldehyde from HMT in high-level consumers of Provolone cheese equaled 18 µg formaldehyde/kg bw/day in adults and could be as high as 87 µg formaldehyde/kg bw/day in children. This estimate was based on a theoretical, conservative assumption that all ripened cheese consumed was Provolone cheese.

Considering the estimated exposure from this very limited permitted use, the toxicological database on HMT, the data from therapeutic use of HMT, the available oral toxicity and toxicokinetic data of formaldehyde, and the magnitude of the potential effect on intracellular formaldehyde levels arising from this use of HMT, the Panel concluded that the use of HMT in Provolone cheese at the MPL of 25 mg/kg residual amount, expressed as formaldehyde, would not be of safety concern.

However, the Panel considered that any increase in the permitted uses of HMT or any increase in the MPL of 25 mg/kg residual amount, expressed as formaldehyde, would require a detailed assessment. This might necessitate new toxicity data as well as updated information on use levels and/or an evaluation of its impact on formaldehyde levels in vivo.