Chemical composition and mutagenic assessment of petrochemical effluents on onion (Allium cepa) root tip mitosis

The continous production and release of chemicals into the environment have led to the need to assess their chemical composition and genotoxic effects on cell reproduction. Two petrochemicals, air liquid and polyester resin effluents were assessed. The common onion of the purple variety was used as the test organism. The results of the chemical analysis of the wastewaters showed high concentration of some potentially mutagenic heavy metals. The effects of the wastewaters and their dilutions on root tip mitosis were mitodepressive. The mitotic index (MI%) were 14.0, 5.3 and 4.1 in control, air liquid and polyester resin effluents, respectively. The MI (%) values estimated across concentrations ranged from 15.1 in control to 5.5 in undiluted effluent. Percent abnormal dividing cells increased with increase in wastewater concentration. Abnormal dividing cells observed ranged from C-mitotic effects to precocious chromosomes and anaphase bridges. These findings indicate the cytotoxic and genotoxic effects of these wastewaters on Allium cepa chromosomes. Positive results on Allium chromosomes could serve as indicator of the deleterious effects of these wastewaters on other organisms at the point of discharge – either on land or water bodies. The need for sound sewerage system that would protect flora and fauna in the ecosystem is advocated.Key words: Chromosome, ecosystem, heavy metal, mitosis, mutation