Mutagenicity in organic extracts of the dust derived from an aluminum electrolytic plant for Salmonella typhimurium

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Mutagenicity in organic extracts of the dust derived from an aluminum electrolytic plant for Salmonella typhimurium

Objective To study the mutagenic activity of the organic extract and its five fractions of the dust collected from an aluminum electrolytic plant in so as to find out the genetic toxicants with stronger mutagenic activity.Methods The dust derived from aluminum electrolytic plant was collected on a fiberglass filter within the scope of the operator's breathing air. Four samples were equidistantly placed in the electrolytic plant. The sampling time lasted for 2 days. Before and after each sampling period, the filter was conditioned at constant relative humidity (50%±2%) and temperature (22℃±2℃) for 24 h and weighted to obtain the weight of suspended dust. The dust-laden filter was placed in Soxhlet extractor and the organic material was extracted for 8 h with 250 ml of spectrograde benzene. The benzene solution was filtered, concentrated to 10 ml and then lyophilized to have the dust organic extract. The dust organic extract was fractionated with a modified method of Wynder and Hoffmann into three fractions: organic acid, organic alkali and neutral. The neutral part was divided into aliphatic hydrocarbon, polycyclic aromatic hydrocarbon and polar compounds. The dust organic extract and its five fractions were dissolved in DMSO, and stored in the dark at 4℃. The mutagenic activities of these fractions were detected with two Salmonella typhimurium strains (TA98 and TA100). Both of the two strains bring R factor, and very sensitive to mutagenic activity of environmental pollutant. Based on the results of four-step method, they accorded with the experimental standard. A 9000g liver supernatant S9 was prepared from Aroclor 1254-induced male Wistar rats. In the tests of metabolic activation, 50 μl of S9 was used in a plate. Ames test was performed essentially according to the procedure described by Maron and Ames. Dust organic extract and its five fractions were dissolved in DMSO. Three doses of the test were 200 μg/plate, 400 μg/plate and 800 μg/plate, respectively. Meanwhile, blank and positive controls were used, each treatment in triplicate. All of the tests were repeated 3 times.Results Mutagenic activities of the dust organic extract and its five fractions were different from one another although within the concentration range of the test, the dust organic extract and its five fractions all increased in revertants for TA98 and TA100. After addition of S9, revertants increased slightly. Mutagenic activity of the dust organic extract was very strong for TA98 and TA100, and after adding S9, it was higher than that without S9. All polycyclic aromatic hydrocarbon showed a mutagenic activity for TA98 and TA100, with and without S9. All polar compounds, detected for TA98, with and without S9, showed mutagenic activities, but they could result in mutagenic activity for TA100 at the concentrations of 400-800 μg/plate only. Organic acid showed mutagenic activity only at the concentrations of 400-800 μg/plate for TA98 and TA100, with and without S9. In the same conditions, no mutagenic activities were detected in the other two fractions, namely organic alkali and aliphatic hydrocarbon, either for TA98 or TA100, with and without S9.Conclusions The dust organic extract derived from an aluminum electrolytic plant and its three fractions, namely organic acid, polycyclic aromatic hydrocarbon and polar compounds, showed mutagenic activities. According to the results of this study, protective measures should be taken to abate the dust in aluminum plants, control carcinogens and mutagens, and to protect the environment and human health.