2,6-Dinitrotoluene

Commercial dinitrotoluene (DNT) production for toluene diisocyanate (TDI — the precursor for polyurethane foam) produces primarily 2,4-DNT with 2,6-DNT as a minor isomer [1]. In TNT (2,4,6-trinitrotoluene) production, 2,6-DNT is also formed as a side product. Both isomers contaminate soil and groundwater at military ordnance sites, former munitions factories, and TDI production facilities worldwide [2]. The United States has hundreds of military installations with DNT contamination from historical TNT production. 2,6-DNT was for many years considered less important than the 2,4-isomer, but toxicological studies showed it may have greater genotoxic potency [1].

Private well users near military ordnance facilities and former TNT production plants face groundwater exposure [1]. Occupational exposure occurs in TDI and TNT manufacturing [2]. Soil contact and dust inhalation near contaminated sites represent additional exposure routes [1].

2,6-DNT is metabolically activated by nitroreductase to hydroxylamine intermediates that form DNA adducts at guanine — possibly more efficiently than the 2,4-isomer [1]. Animal studies showed testicular atrophy and liver tumors. EPA classifies DNT mixed isomers (dominated by 2,4- and 2,6-DNT) as a probable carcinogen [2]. Like other nitroaromatics, it causes methemoglobinemia at higher doses [1].

Private well users near military and former ordnance production sites [1]. TDI and explosives manufacturing workers [2].

1. Test your well if near military sites — request DNT isomer analysis [1]. 2. Activated carbon filtration for contaminated water [2]. 3. Workers in TDI synthesis should use biological monitoring programs [1].