Bioaccumulation of heavy metals in tea marketed in Nigeria was investigated. Four major and most consumed brand of tea were selected for the present study. Both aqueous and dry methods were used. Total contents of met...Bioaccumulation of heavy metals in tea marketed in Nigeria was investigated. Four major and most consumed brand of tea were selected for the present study. Both aqueous and dry methods were used. Total contents of metal were determined by digesting 1g of each brand using a mixture (3:1) concentrated nitric acid (NNO3) and hypochlorous acid (HCLO4). The second method involved hot water extract of tea samples. After boiling and filtration, the residue was evaporated to near dryness and digested with concentrated HNO3 and HCLO4 as described above. Results indicate that Zn, Cd, Cu, and Pb were present in lowest concentrations in ascending order for which there were two significant differences between the four sources of samples. The general characteristics of heavy metal concentrations in aqueous extract showed high level of Fe and Mg in a descending order. Going by the correlation study of our result indicates that there is no significant relationship between the two elements of Fe and Mg, though, the numerical values of the two elements varied widely among the samples. These differences may have major impact on human health. However, the beneficial effects of tea are in a fairly narrow concentration range between the essential and the toxic level. In conclusion, the variations in heavy metals content of tea brands may be due to geographical, seasonal changes and the chemical characteristics of the growing regions.展开更多
Exposure of animals to different duration of smoke can result in a wide range of adverse clinical conditions. Toxicological consequences arising from prolonged exposure may not be totally enumerated. The present study...Exposure of animals to different duration of smoke can result in a wide range of adverse clinical conditions. Toxicological consequences arising from prolonged exposure may not be totally enumerated. The present study was to evaluate the oxidative stress-inducing potential of a short and long-time exposure of male rat erythrocytes to environmentally relevant to public health. Male Wistar rats were exposed to open municipal land-fill smoke for 30 and/or 60 days. The oxidative stress in erythrocytes was evaluated by assessing the magnitude of malondialdehyde production and reduced glutathione (GSH) contents and the activities of superoxide dismutase (SOD), catalase (C) and glutathione reductase (GR) after 30 and/or 60 days of exposure. After 30 days there was no change in SOD, catalase and GR activities and no alterations in GSH and lipid peroxidation (LPO). After 60 days, the levels and activities of SOD (23.62%), catalase (5.24%), GR (14.87%) decreased. Overall, the study demonstrates that the chronic exposure of male rats to smoke results in induction of oxidative stress and simultaneous reduction in antioxidative defense system in erythrocytes at 60 days of exposure.展开更多
文摘Bioaccumulation of heavy metals in tea marketed in Nigeria was investigated. Four major and most consumed brand of tea were selected for the present study. Both aqueous and dry methods were used. Total contents of metal were determined by digesting 1g of each brand using a mixture (3:1) concentrated nitric acid (NNO3) and hypochlorous acid (HCLO4). The second method involved hot water extract of tea samples. After boiling and filtration, the residue was evaporated to near dryness and digested with concentrated HNO3 and HCLO4 as described above. Results indicate that Zn, Cd, Cu, and Pb were present in lowest concentrations in ascending order for which there were two significant differences between the four sources of samples. The general characteristics of heavy metal concentrations in aqueous extract showed high level of Fe and Mg in a descending order. Going by the correlation study of our result indicates that there is no significant relationship between the two elements of Fe and Mg, though, the numerical values of the two elements varied widely among the samples. These differences may have major impact on human health. However, the beneficial effects of tea are in a fairly narrow concentration range between the essential and the toxic level. In conclusion, the variations in heavy metals content of tea brands may be due to geographical, seasonal changes and the chemical characteristics of the growing regions.
文摘Exposure of animals to different duration of smoke can result in a wide range of adverse clinical conditions. Toxicological consequences arising from prolonged exposure may not be totally enumerated. The present study was to evaluate the oxidative stress-inducing potential of a short and long-time exposure of male rat erythrocytes to environmentally relevant to public health. Male Wistar rats were exposed to open municipal land-fill smoke for 30 and/or 60 days. The oxidative stress in erythrocytes was evaluated by assessing the magnitude of malondialdehyde production and reduced glutathione (GSH) contents and the activities of superoxide dismutase (SOD), catalase (C) and glutathione reductase (GR) after 30 and/or 60 days of exposure. After 30 days there was no change in SOD, catalase and GR activities and no alterations in GSH and lipid peroxidation (LPO). After 60 days, the levels and activities of SOD (23.62%), catalase (5.24%), GR (14.87%) decreased. Overall, the study demonstrates that the chronic exposure of male rats to smoke results in induction of oxidative stress and simultaneous reduction in antioxidative defense system in erythrocytes at 60 days of exposure.
