Potential toxicological effects of amines used for carbon capture and storage and their degradation products

With the increasing use of amine solvents for carbon capture, there is a critical need to characterize the potential health effects of these materials and their degradation products formed within the capture system or downwind of release. This study evaluated the acute inhalation health risk of exposure to degraded mixtures of monoethanolamine (MEA), methyldiethanolamine (MDEA), and piperazine (PIP). Degradation was achieved in a heated (150C) and pressurized (approximately 15 psi) stainless steel vessel by adding NO2 and purified air over approximately 75 days. Laboratory mice were exposed to the degraded mixture (as well as the neat amines in separate experiments) 6hrs/day for 7 consecutive days in a whole-body inhalation chamber. Bronchoalveolar lavage (BAL) was carried out 18 to 24hours post-exposure and inflammatory cells were counted in lavage fluid. Cytokine expression and oxidative stress were measured in lung tissue. We found that exposure to degraded MEA resulted in significant increases in total cells, neutrophils, and lymphocytes, and the strongest cytokine response compared to control mice and compared to MEA-exposed mice. Neither MDEA nor PIP, or their degradant mixtures, caused increased inflammatory cells in BAL fluid. The degraded MEA atmosphere also caused a statistically significant decrease in oxidative stress in mouse lung. The degraded MDEA atmosphere caused the strongest cytokine response of the amines tested, producing statistically significant increases in cytokine growth-related oncogene (GRO-KC), monocyte chemotactic protein -1 (MCP-1), and granulocyte-macrophage colony stimulating factor (GMCSF) expression compared to the control and to MDEA alone. The degraded PIP atmosphere showed a statistically significant increase in GMCSF expression. This investigation represents a hazard evaluation and not a dose-response assessment; however, the results suggest that our approach can be used successfully to screen potential solvents for carbon capture for acute human health impacts.