Genotoxicity of SPL (spent pot lining) as measured by Tradescantia bioassays.

Spent Pot Liner (SPL) is a solid waste product generated in the process of aluminum production. Tradescantia micronuclei (Trad-MN) and stamen hair mutation (Trad-SHM) bioassays are very useful tests to assess genotoxicity of environmental pollutants. In the present study, we intended to investigate the genotoxicity of this waste with Tradescantia bioassays using leachates of SPL simulating the natural leachability of SPL in soil. The formation of micronuclei (MN) was found to be concentration dependent. MN frequency enhanced significantly with SPL treatment. In addition, SPL also appeared to increase the percentage of dyads and triads. Trad-SHM assay showed that SPL increases pink mutation events as SPL concentration increases. These results demonstrated that SPL is a cytogenotoxic agent that affects different genetic end-points (induction of micronuclei and point mutations) even at low concentration (2% and 3%).

Spent Pot Liner (SPL) induced DNA damage and nuclear alterations in root tip cells of Allium cepa as a consequence of programmed cell death.

There are various toxic effects of environmental pollutants, including apoptosis and carcinogenesis. Spent Pot Liner (SPL) is solid waste from the aluminum industry. It has a highly variable composition, including cyanide, fluoride, organics and metals. Preliminary characterizations of the effect of SPL on Allium cepa show the presence of condensed nuclei. Thus, the aim of this study was to analyze the toxic effect of SPL in A. cepa root meristem in the context of programmed cell death (PCD). A lot of specific features of this process such as DNA fragmentation, condensed chromatin, spherical nuclei and the formation of apoptotic-like bodies were observed in root meristem after SPL treatment. Root meristem treated with SPL 25% solution exhibited an alteration in antioxidant enzyme activities; a reduction in NCR as a consequence of high percentage of condensed nuclei; DNA fragmentation, detected by electrophoresis and TUNEL assay; cytoplasm vacuolization and also a disturbance in root morphology. These features are associated with programmed cell death (PCD) under abiotic stress. Therefore, these data show that SPL induces apoptosis-like PCD in root meristem cells of A. cepa.