Olivares, C.I., Sierra-Alvarez, R., Abrell, L., Chorover, J., Simonich, M., Tanguay, R.L., Field, J.A. (2016) Zebrafish embryo toxicity of anaerobic biotransformation products from the insensitive munitions compound 2,4-dinitroanisole (DNAN). Environmental toxicology and chemistry. 35(11):2774-2781.
2,4-dinitroanisole (DNAN) is an emerging insensitive munitions compound that readily undergoes anaerobic nitro-group reduction to 2-methoxy-5-nitroaniline (MENA) and 2,4-diaminoanisole (DAAN), followed by subsequent formation of unique azo-dimers. Currently there is scarce knowledge on the ecotoxicity of DNAN (bio)transformation products. In this work, mortality, development, and behavioral effects of DNAN (bio)transformation products were assessed using zebrafish (Danio rerio) embryos. We tested individual products, MENA and DAAN, as well as dimer and trimer surrogates. As pure compounds, 3-nitro-4-methoxyaniline and 2,2'-dimethoxy-4,4'-azodianiline caused statistically significant effects with Lowest Observable Adverse Effect Levels (LOAELs) at 6.4 µM on one or two developmental endpoints, respectively. The latter had six-additional statistically significant developmental endpoints with LOAELs of 64 µM. Based on light/dark swimming behavioral tests, DAAN (640 µM) caused reduction in swimming, suggestive of neurotoxicity. No statistically significant mortality occurred (≤ 64 µM) for any of the individual compounds. However, metabolite mixtures formed during different stages of MENA (bio)transformation in soil were characterized using high-resolution mass spectrometry in parallel with zebrafish embryo toxicity assays, which demonstrated statistically significant mortality during the onset of azo-dimer formation. Overall the results indicate that several DNAN (bio)transformation products cause different types of toxicity to zebrafish embryos. This article is protected by copyright. All rights reserved.