2,4-Dinitrotoluene (DNT)

DNT is produced by nitrating toluene — a process first developed in Germany in the 1860s as part of the early synthetic dye chemistry that would evolve into the explosives industry [1]. DNT is an intermediate in manufacturing trinitrotoluene (TNT) and also the primary starting material for toluene diisocyanate (TDI), which is used to make flexible polyurethane foam for mattresses, furniture, and car seats [2]. Military ordnance facilities around the world processed millions of tons of DNT through the twentieth century, contaminating soils and groundwater at many sites — DNT and its metabolites are found in groundwater at dozens of U.S. Army installations [1]. Polyurethane foam manufacturing represents the continuing large-scale use pathway; EPA and IARC classify DNT as a probable/possible carcinogen based on Leydig cell testicular tumors and liver tumors in rats [2].

Contaminated groundwater and soil at former military manufacturing and testing sites is the primary environmental pathway for general population exposure [1]. People living near Superfund sites with ordnance or explosives contamination may have DNT in their drinking water or experience skin contact from contaminated soil [2]. Occupational exposure in polyurethane foam manufacturing — during the synthesis and handling of TDI which uses DNT as a feedstock — involves potential inhalation and dermal contact [1]. Munitions workers at facilities that still manufacture military ordnance are the highest-exposure group [2]. Some residual dietary exposure may occur from contaminated agricultural products grown on former military land [1].

DNT is metabolically activated by liver enzymes to reactive hydroxylamine intermediates that bind DNA, accounting for its hepatotoxic and genotoxic properties [1]. In chronic rat feeding studies, DNT induced Leydig cell tumors in the testes (affecting testosterone production) and hepatocellular tumors — forming the basis for EPA's Group B2 (probable human carcinogen) classification [2]. Occupational exposures have been associated with anemia (methemoglobin formation), liver damage (elevated enzymes, hepatomegaly), and peripheral neuropathy in heavily exposed workers [1]. Like many nitroaromatic compounds, DNT causes methemoglobinemia — oxidizing hemoglobin to a form that cannot carry oxygen — at high acute doses [2].

Residents near former munitions plants, military ordnance facilities, and Army Superfund sites are most exposed through groundwater and soil contamination [1]. Munitions factory workers and military ordnance handlers have the highest occupational exposures [2]. Polyurethane foam and chemical workers who handle DNT as a TDI feedstock are also occupationally exposed. Men may be especially vulnerable given the testicular Leydig cell tumor findings in animal studies, raising concern about testosterone and fertility effects [1]. People with glucose-6-phosphate dehydrogenase (G6PD) deficiency are more susceptible to DNT-induced methemoglobinemia [2].

1. If you live near a former military base or explosives manufacturing site, check EPA's Superfund site database and your state's environmental agency for groundwater monitoring data on DNT [1]. 2. Test your private well if you are in a potentially affected area; activated carbon filtration reduces organic contaminant levels in drinking water [2]. 3. If you work in polyurethane foam or isocyanate chemistry, request your workplace's air monitoring data for DNT and TDI; participate in biological monitoring programs if offered [1]. 4. Wear appropriate PPE including impervious gloves and chemical splash goggles when handling DNT-containing materials; it is readily absorbed through skin [2]. 5. Inquire about soil testing before purchasing property near former industrial or military sites in regions with explosives manufacturing history [1].