This study evaluates the toxicity of 25 nitroaromatic compounds, including nitroanilines and nitrotoluenes, based on their effects on Pseudokirchneriella subcapitata. A closed-system algal toxicity test was applied because these chemicals are semi-volatile/volatile substances. The dissolved oxygen production (DO) was used as the test endpoint which reflects the degree of inhibition of toxicants on algal photosynthesis reactions. EC50 and NOEC values of various nitroaromatic compounds were determined. Two toxicants (2,6-Dinitroaniline and 3,5-Dinitroaniline) tested in the present study are classified as highly toxic (0.1 mg/L - 1.0 mg/L, R50). There are nine other nitroaromatic compounds are considered as moderately toxic (> 1.0 mg/L - 10 mg/L, R51 class). Pseudokirchneriella subcapitata appears to be the most vulnerable species among all aquatic organisms.Principal component analyses (PCA) and Hierarchical clustering analysis (HCA) were conducted based on the toxicity of chemicals and two physical/chemical parameters (Log P and Elumo). The above analyses, in Fig. 1, agree well with Russom's classification of the mechanisms of chemicals, except for 3-Nitroaniline (ID 2), 3-Nitro-1,4-Benzenediamine (ID 7), and 3-Nitro-1,2-Benzenediamine (ID 10),  and 4-methyl-3-nitroaniline (ID12). Furthermore, these compounds also reveal significantly high excess toxicity as compared to the baseline toxicity relationship. The above analysis indicate that compounds with nitro- substituent on the meta-site to an amine group on the benzene ring are polar narcotic or reactive in nature.

Toxicity and mechanisms of nitroaromatic compounds on algal photosynthesis reaction

246th National Meeting (2013)

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