Exposure to complex mixtures like textile effluent poses risks to animal and human health such as mutations, genotoxicity, pathological lesions and oxidative damage. The aim of the present study was to quantify metals and identify organic pollutants in untreated textile dyeing industry wastewater, to determine the bacterial load of wastewater, isolate and identify heavy metals tolerant bacteria and to determine its mutagenic, genotoxic and cytotoxic potential, influence on normal physiology and effects on oxidative stress biomarkers in effluent exposed rats.
Metal analysis through AAS revealed presence of high amounts of zinc, copper, chromium, iron, arsenic and mercury in industrial effluent. Various organic pollutants such as chlorpyrifos, cucurbitacin-b and phthalates were identified by screening through GC-MS.
Microbiological evaluation of textile dyeing industry wastewater revealed a high bacterial load. Different bacteria isolated from wastewater such as Staphylococcus aureus, Pseudomonas aeruginosa, Corynebacterium xerosis, Bacillus megaterium, Staphyoloccus epidermidis and Micrococcus varians exhibited resistance to Cr and Cu salts and antibiotics to varying degree.
Ames test with/without enzyme activation and MTT assay showed strong association of industrial effluent with mutagenicity and cytotoxicity respectively. Bacterial reverse mutation assay revealed that the mutagenicity of textile dyeing industry wastewater decreased with increase in dilution of wastewater.
In-vitro comet assay revealed the evidence of high oxidative DNA damage induced by textile wastewater. Wastewater exhibited concentration dependent genotoxicity in sheep
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peripheral lymphocytes. When Wistar rats were exposed to industrial effluent in different dilutions for 60 days, then activities of total superoxide dismutase and catalase and hydrogen peroxide concentration were found to be significantly lower in kidney, liver and blood/ plasma of effluent exposed rats than control. Vitamin C at a dose of 50mg/Kg/day significantly reduced oxidative effects of effluent in rats. Industrial effluents may decrease activities of T-SOD and CAT and concentration of H2O2 in liver, kidney and blood/plasma of Wistar rats. Vitamin C may have a possible ameliorating effect on industrial effluent induced oxidative stress in Wistar rats.
Wastewater exposed rats exhibited necrosis of epithelial cells of nephron, pulmonary emphysema, and inflammation of the lungs, degradation and infiltration of cardiac myocytes, fibrosis of the liver, damage to the intestinal mucosa and sloughing off epithelial cells from the intestinal lumen.
This study concludes that untreated textile dyeing wastewater being a complex mixture of inorganic and organic pollutants may be highly eco-toxic and may contaminate of the environment via continuous release of various organic and inorganic pollutants.