Hexamethylenetetramine: a review

The available literature on hexamethylenetetramine (hexamine) was reviewed with emphasis on its toxicology and epidemiology, its thermal decomposition and regulatory concerns related to its uses. Large quantities of hexamine are used in the foundry, tire and rubber, and phenolformaldehyde resins industries and in other diverse applications. Excessive exposure to solid hexamine or its vapor has been reported to cause dermatitis and respiratory allergies. Although hexamine produces a positive Ames test, most animal studies have shown hexamine to be of very low genetic risk even in very high doses. The effectiveness of hexamine as an antibacterial agent has been attributed to its slow hydrolysis to ammonia and formaldehyde. Concerns have developed in industries which use hexamine at high temperatures over emissions of HCN, NH3, CO, CO2, nitrogen oxides, and formaldehyde. The studies reviewed are in general agreement that hexamine thermal decomposition in the temperature range of 300-800 degrees C is characterized by an increase in HCN and a decrease in NH3 emissions with increasing temperature. At temperatures of 200-300 degrees C hexamine decomposition is reported to produce mainly ammonia and formaldehyde.