Generally in agriculture farmers use pesticides to increase their yield by reducing crop losses by pests. Some chemical compounds used pesticides are mutagens. Present study evaluated the cytotoxic effect of synthetic pesticide "Attack" which is used instead of "Furadan"on root meristems of Allium cepa L. as a test system. The root meristems of A. cepa L. were treated with five concentrations (1%, 2%, 3%, 4% and 5%) of the chemical pesticide "Attack" for 6 h duration. Exposure to different concentrations of pesticide showed an inhibitory effect on cell division in root tip cells of A. cepa and caused a general decline in Mitotic Index values. Additionally, a wide range of abnormal mitotic stages, were detected in treated cells when compared to control. The total percentage of aberrations generally increased in a dose dependant manner. Among these, frequently observed chromosomal abnormalities were despiralized prophase, disoriented prophase, vagrant prophase, diagonal metaphase, C-metaphase, vagrant metaphase, clumped metaphase, star anaphase, diagonal anaphase, anaphase with two bridges and with multiple bridges, aticky anaphase, telophase stickiness, hyperchromasia, bi-nucleate and 4 nucleate cells and micronucleus. The results of the present study clearly proved the sensitivity of Allium test and hence substantiate its use as a cytogenetic assay to assess the cytogenetic effect of chemical widely used as pesticides. The cytotoxic pesticides have potential to cause adverse environmental and health effects by inducing chromosomal abnormalities leading to mutations.

Screening for mutagens in complex environmental mixtures, such as surface water or industrial wastewater, is gradually being accepted as a routine method in environmental monitoring programs. In the present work, the simplified Allium cepa root assay was utilized to evaluate the possible cytotoxic effect of sewage effluent on root tip cells of A. cepa L. Sewage effluents were collected from Kunnamkulam market. Treatements were done in five different time durations such as 3, 6, 12, 24, and 48 hours. Allium cepa exposed to sewage effluents resulted to cells with chromosomal aberration. The Mitotic index was decreased when the time durations were increased. The mitotic index of the control was 49.65±3.35. The mitotic index of the sewage effluent in 3 hr was 42.28±3.37. From this a gradual decrease in the mitotic index when the duration of time increased. The mitotic index 42.15±3.17, 32.27±3.04, 31.65±3.19 and 28.19±2.87 are 6 h, 12 hr, 24 h and 48 h respectively chromosomal abnormalities such as bridges, fragments, vagrant chromosomes, sticky chromosomes, C-mitosis, spindle abnormalities and disoriented chromosomes were observed. The impacts of using sewage effluent as fertilizer on the environment are difficult to predict. So they may be treated to remove its toxic particles prior to its release into the environment. Toxicity or genotoxicity bioassays should be an integral tool in the evaluation of waste water toxicity.