The MI value of AWW showed a decline from 44.7 to 37.8 to the extent of 15.4% whereas the presence of mannitol in the treatment tubes brought it upto 41.2 exhibiting a recovery of 8.25%. Chromosomal aberration based on its index showed its value for AWW treated A.cepa to be 11.2% compared to 2.6%

for the aquaguard water. The aberration index showed 52% reduction in the presence of mannitol. Interestingly, lead nitrate also exhibited the MI value, the chromosomal aberrations and aberration index very close to those of AWW. Water pollution has attracted a lot of interest in recent years due to its multidimensional hazardous effects. Disposal of the treated as well as untreated disposal of industrial waste material leads to serious problems for human health and survival. Oil refineries as well BMN 673 purchase as other industries generate huge amount of sludge containing both organic and inorganic toxicants which pollute the nearby sites. Many of the constituents in the wastes are carcinogenic and potent immunotoxicants [15]. To monitor the harmful effects of pollutants, a number of toxicity bioassays have been developed. Allium cepa test introduced by Levan [16] has been used frequently and validated by several workers for testing chemical pollutants posing hazardous

environmental effects ( [13], CHIR-99021 order [17], [18] and [19]). Root growth inhibition of Allium cepa was used as an indicator of toxicity of the refinery waste water and Aligarh waste water. The IC50 value in A. cepa system was recorded to be 0.14 X for RWW and 0.10 X for Aligarh waste water in the year 2008. Since water bodies represent a highly dynamic system, the degree of toxicity induced by industrial effluents can surely change over a period of time. Recent study in mafosfamide our lab [20] on the phytotoxic potential

of RWW suggested the IC50 value to be 0.75X. Thus, it can be concluded that from the year 2008 to 2011, there was a definite hike in the IC50 value from 0.14 X to 0.75X. This increase in the IC50 value from 2008 to 2012 signifies a reduced toxic potential of RWW, which might be the outcome of the installation of treatment plants in the refinery. These treatment plants must have detoxified or blocked the release of certain toxicants into water bodies. Toxicity of several other industrial waste samples have been determined in terms of IC50 values employing A. cepa system [21]. In addition to significant phytotoxicity of the RWW, present study also establishes its genotoxic potential in terms of significantly decreased survival of the DNA repair defective mutants of the E. coli K12 ( Figure 2, 3). The efficacy of the E. coli 12 repair defective mutants of E.coli K12 in assaying the genotoxicity of waste water has been well established (IGGE 1990; [22] and [23]).