Frontiers in Genetics (May 2015)
In vivo genotoxicity of nitramines, transformation products of amine-based carbon capture technology
Abstract
In times where we need to reduce our CO2 emissions to the atmosphere, it is important to get a clearer picture of the environmental impacts associated with potential mitigation technologies. Chemical absorption with amines is emerging as the most advanced mitigation technology for post-combustion capture of CO2 from fossil fuel power stations. Although the amine solvent used in this technology is recycled during the capture process, degradation products are formed and released into the environment. Among these degradation products, the aliphatic nitramine compounds dimethylnitramine and ethanolnitramine have been identified, whose environmental impact was unknown. In addition to conducting survival, growth and reproduction tests in a range of marine species, we looked into the in vivo genotoxic potential of these two compounds to experimentally exposed fish (Coutris et al. 2015). DNA damage was analyzed in blood samples collected from the caudal vein of juvenile turbot Scophthalmus maximus after 28 day exposure to nitramines, using the 12 mini-gels version of the comet assay, with and without digestion with formamidopyrimidine DNA glycosylase. Although whole organism bioassays indicated that nitramine toxicity through necrosis was low, the genotoxicity assessment revealed contrasting results, with ethanolnitramine found to be more genotoxic than dimethylnitramine by three orders of magnitude. At the lowest ethanolnitramine concentration (1 mg/L), 84 % DNA damage was observed, whereas 100 mg/L dimethylnitramine was required to cause 37 % DNA damage. The mechanisms of genotoxicity were also shown to differ between the two compounds, with oxidation of the DNA bases responsible for over 90 % of the genotoxicity of dimethylnitramine, whereas DNA strand breaks and alkali-labile sites were responsible for over 90 % of the genotoxicity of ethanolnitramine. Fish exposed to > 3 mg/L ethanolnitramine had virtually no DNA left in their red blood cells. The large difference in genotoxicity observed between the two nitramine compounds highlights the danger of inferring toxicity from structurally similar compounds for environmental risk assessment, and conversely shows the importance of compound specific assessments.
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