Abstract
Exposure to toxic metals (TMs) such as cobalt (Co) can cause lifelong carcinogenic disorders and mutagenic outcomes. TMs enter ground water and rivers from human activity, anthropogenic contamination, and the ecological environment. The present study was conducted to evaluate the influence of sewage water irrigation on cobalt (Co) toxicity and bioaccumulation in a soil-plant environment and to assess the health risk of grazing livestock via forage consumption. Cobalt is a very necessary element for the growth of plants and animals; however, higher concentrations have toxic impacts. Measurement of Co in plant, soil and water samples was conducted via wet digestion method using an atomic absorption spectrophotometer. The Co pollution severity was examined in soil, forage crops (Sorghum bicolor Kuntze, Sesbania bispinosa (Jacq.) W. Wight, Cynodon dactylon (L.) Pers., Suaeda fruticosa (L.) Forssk. and Tribulus terrestris L.) in blood, hair and feces of sheep, cow and buffalo from district Toba-Tek-Singh, Punjab, Pakistan. Three sites were selected for investigation of Co level in soil and forage samples. Highest concentration of Co was 0.65 and 0.35 mg/kg occurring in S. bicolor at site I. The sheep blood, cow hair and sheep feces samples showed highest concentrations of 0.545, 0.549 and 0.548 mg/kg, respectively at site I and site II. Bioconcentration factor, pollution load index, enrichment factor and daily intake were found to be higher (0.667, 0.124, 0.12 and 0.0007 mg/kg) in soil, S. bicolor, S. fruticosa and in buffalo, respectively, at site I. It was concluded that forage species irrigated with wastewater are safe for consumption of livestock. However, though the general values were lower than the permissible maximum limit, it was observed that the bioaccumulation in the forage species was higher. Therefore, soil and food chain components should be avoided from trace metal contamination, and other means of nonconventional water resources should be employed for forages irrigation.