The US Army is replacing traditional munitions with insensitive munitions resistant to accidental detonation. Although the parent insensitive munition compound nitroguanidine (NQ) is generally not acutely toxic at concentrations >1000 mg/L in aquatic exposures, products formed by intensive ultraviolet (UV) degradation resulted in multiple-order of magnitude increases in toxicity. A methylated congener of NQ, 1-methyl-3-nitroguanidine (MeNQ), is also being assessed for potential use in insensitive munition explosive formulations; therefore, the present study investigated the hazard of parent versus UV-degraded MeNQ using fathead minnows (Pimephales promelas). Although up to 716 mg/L parent MeNQ caused no significant mortality or effects on growth in larval P. promelas fish in 7-d exposures, a similar concentration of MeNQ subjected to UV treatment resulted in 85% mortality. The UV treatment degraded only 3.3% of the MeNQ (5800 mg/L stock, UV-treated for 6 h), indicating that MeNQ degradation products have potentially high toxicity. The parent MeNQ exposure caused significantly decreased transcriptional expression of genes within the significantly enriched insulin metabolic pathway, suggesting antagonism of bioenergetics pathways, which complements observed, although nonsignificant, decreases in body weight. Significant differential transcriptional expression in the UV-degraded MeNQ treatments resulted in significant enrichment of pathways and functions related to the cell cycle, as well as erythrocyte function involved in O2 /CO2 exchange. These functions represent potential mechanistic sources of increased toxicity observed in the UV-degraded MeNQ exposures, which are distinct from previously observed mechanisms underlying increased toxicity of UV-degraded NQ in fish. Environ Toxicol Chem 2020;39:612-622. © 2019 SETAC.

中文翻译：

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紫外光降解与母体不敏感的弹药化合物1-甲基-3-硝基胍在Fathead Minnow中的比较毒理学评估。

美国陆军正在用不敏感的弹药代替传统的弹药，这种弹药可以抵抗意外爆炸。尽管母体不敏感弹药化合物硝基胍（NQ）在水中暴露浓度> 1000 mg / L时通常没有剧毒，但由于强烈的紫外线（UV）降解而形成的产品导致毒性增加了多个数量级。还正在评估NQ的甲基化同类物1-甲基-3-硝基胍（MeNQ）在不敏感弹药炸药配方中的潜在用途。因此，本研究使用黑头min鱼（Pimephales promelas）研究了母体与紫外线降解的MeNQ的危害。尽管高达716 mg / L的亲本MeNQ在7天的暴露中并未引起幼虫P. promelas鱼的明显死亡率或生长影响，相似浓度的MeNQ经过紫外线处理后，死亡率达到了85％。紫外线处理仅降解了3.3％的MeNQ（5800 mg / L储备液，经过紫外线处理6小时），表明MeNQ降解产物具有潜在的高毒性。亲本MeNQ暴露会导致胰岛素代谢途径显着丰富，从而显着降低基因的转录表达，这表明对生物能途径的拮抗作用，对体重的减轻（尽管不显着）起到了补充作用。在紫外线降解的MeNQ处理中，显着的差异性转录表达导致与细胞周期相关的途径和功能以及与O2 / CO2交换有关的红细胞功能的显着丰富。这些功能代表了在紫外线降解的MeNQ暴露中观察到的增加毒性的潜在机理源，这与以前观察到的在鱼类中紫外线降解的NQ毒性增加的潜在机理不同。Environ Toxicol Chem 2020； 39：612-622。©2019 SETAC。