Levels of Mercury (Hg), Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni) & Thallium (Tl) were established in wastewater & soil samples obtained from 8 sites in open drainage channels at Nairobi industrial area, Kenya. Ultra-trace inductively coupled plasma mass spectroscopy (ICP-MS) was used for metal analysis. Temperature, pH & turbidity of wastewater ranged from 16.75 to 26.05 °C; 7.28 to 8.78; 160.33 to 544.69 ppm respectively and within World Health Organization (WHO) allowable limits. Wastewater conductivities in 4 sites ranged from 770 to 1074 µS/cm and above WHO limits at 25 °C. The mean concentrations of the metals in wastewater ranged from 0.0001 to 0.015 ppm in an ascending order of Tl <Cd <Hg <Ni <Cr <Pb. Levels of Cd, Cr & Ni in wastewater were within WHO, World Bank (WB), United States Environmental Protection Agency (US EPA), China, Kenya and India’s Central Pollution Control Board (CPCB) limits while Hg & Tl were above US EPA limits. The mean Pb levels in wastewater (5 sites) were above WHO, US EPA and Kenya allowable limits. Mean levels of the metals in soil samples ranged from 0.085 to 199.99 ppm, with those of Hg, Pb, Cr, Cd & Ni being above WHO limits for agricultural soils. Positive correlations (P < 0.05) for Cd & Hg in soils; and Tl (wastewater) & Cd (soil) were noted. In conclusion, wastewater in open waste channels at Nairobi industrial area had elevated levels of Pb and Hg, while the soil from the same channels had high levels of Hg, Pb, Ni, Cr, and Cd. Good management of Nairobi industrial area effluents is inevitable since it borders densely populated informal settlements which are likely to suffer exposure to toxic wastes. Effective wastewater treatment and reuse is highly recommended.
Plant extracts from Warburgia ugandensis Sprague (Family: Canellaceae), Psiadia punctulata Vatke (Family: Compositae) and Chasmanthera dependens Hoschst (Family: Menispermaceae) were tested for activity on Leishmania major promastigotes (Strain IDU/KE/83 = NLB-144) and infected macrophages in vitro. Plants were collected from Baringo district, dried, extracted, weighed and tested for antileishmanial activity. Serial dilutions of the crude extracts were assayed for their activity against Leishmania major in cell free cultures and in infected macrophages in vitro. Inhibitory concentrations and levels of cytotoxicity were determined. Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens had an IC(50) of 1.114 mg/ml, 2.216 mg/ml and 4.648 mg/ml, respectively. The cytotoxicity of the drugs on BALB/c peritoneal macrophage cells was insignificant as compared to the highly toxic drug of choice Pentostam(®). The supernatants from control and Leishmania infected macrophages were analyzed for their nitrite contents by Griess reaction and nitrite absorbance measured at 540 nm. Warburgia ugandensis (stem bark water extract), Chasmanthera dependens (stem bark water extract) and Psiadia punctulata (stem bark methanol extract) produced 112.3%, 94% and 88.5% more nitric oxide than the untreated infected macrophages respectively. Plant crude extracts had significant (p<0.05) anti-leishmanial and immunomodulative effects but insignificant cytotoxic effects at 1mg/ml concentration. All experiments were performed in triplicate. Statistical analysis of the differences between mean values obtained from the experimental group compared to the controls was done by students't test. ANOVA was used to determine the differences between the various treatment groups. The analysis program Probit was used to determine IC(50)s.
The Article contains a typographical error in Table 2 where the WHO recommended limit for Hg in Soils (for agriculture) was incorrectly given as "-0.08" ppm. The correct recommended limit should read as "0.05-0.08" ppm.
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