Insensitive munitions (IMs) provide increased soldier safety via decreasing the likelihood of sympathetic detonations during their manufacture, shipping, storage, and use. IMX-101 is a triple base, melt-cast explosive containing dinitroanisole (DNAN), nitrotriazolone (NTO), and nitroguanidine (NQ). The toxicity of the constituents (LC50 = 25, 1235, 1486, and 63 mg/L for DNAN, NTO, NQ, and the IMX-101 mixture, respectively in Daphnia pulex) are lower than the toxicity of trinitrotoluene (TNT, 4.03 mg/L in Daphnia magna), the compound IMX-101 is to replace. However, upon irradiation by intense laboratory UV light the toxicity of NQ is increased 100 to 1000 fold over the parent material, leading to challenges with wastewater discharge at manufacturing facilities requiring new treatment methods to be integrated. This has spurred research towards identifying which of the many products generated lead to this multiple order of magnitude increase in toxic responses to the tested organisms. Understanding the mechanisms of this degradation process and toxicity have been explored experimentally and computationally, finding inorganic (nitrite, nitrate, ammonia, cyanide) and organic (cyanamide, cyanoguanidine, nitrosoguanidine) chemicals as photo-degradation products, and various modes of oxidative stress leading which can result in organismal death. Interestingly, the onset of the 100-fold increase in toxicity to D. pulex occured when only a modest proportion of the parent NQ has been UV-transformed (~5%). Further, the UV-photolysis products are relatively stable where the increased toxicity in D. pulex was persistent after UV-treated solutions were allowed to age on a laboratory bench for 8 days. Work is currently underway to determine the toxicity of the identified products, with further planned research efforts focusing on the toxicology of NQ solutions degraded under natural sunlight to determine the veracity of the experiments conducted under intense UV irradiation.

Identification of photo-degradation products of nitroguanidine and toxicological implications

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.