Hexamethylenetetramine is a preservative approved for use in the EU.
In the presence of protein or an acidic environment, hexamethylenetetramine decomposes to produce ammonia and formaldehyde. Formaldehyde rapidly decomposes to formic acid. Hexamethylenetetramine has mutagenic activity in insects and injection of this substance into rats has produced tumor growth. On this basis it was rejected as a food additive by the WHO and Food and Agriculture Organization of the UN in the 1960s. See: Formic acid.
Hexylmethylenetetramine is not approved for use in the USA, Russia, Australia, or New Zealand. In the EU it is only approved for use in protein-rich provolone cheese, thus being broken down to form formaldehyde then formic acid.
Methenamine, hexamine, E239