Chemical Speciation and Characterization of Trace Metals in Dry Camellia sinensis and Herbal Tea Marketed in Nigeria.

BACKGROUND: Trace metals from anthropogenic activities have been found to occur in tea brands and pose potential human health risks to consumers. OBJECTIVES: The present study assessed the concentrations of trace metals in green, black and herbal tea brands using a modified Community Bureau of Reference sequential extraction method. METHODS: Fifteen (15) Camellia sinensis and eight (8) herbal tea samples commonly consumed in Nigeria were collected and analyzed for trace metals. The concentrations of cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) in extract fractions were analyzed using microwave plasma atomic emission spectroscopy (MP-AES). RESULTS: Trace metals were detected in all of the samples investigated. The concentrations of trace metals in 4 stages (soluble/exchangeable/carbonates bound fraction, reducible fraction, oxidizable fraction, residual fraction) of sequential and pseudo-total metal extraction procedures are presented. The concentrations of Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn in the exchangeable/carbonate bound fraction for green tea ranged between 0.27-1.47, ND-0.33, ND-0.44, 7.05-33.04, 0.23-0.69, ND-0.51, ND-0.16 and 0.18-1.99 mg/kg, ND-0.73, 0.15-0.36, 0.36-0.59, 1.38-30.07, 0.15-0.54, 0.05-0.76, 0.15-0.34 and 0.27-0.77 mg/kg and 0.54-0.64, 0.25-0.41, 0.35-0.47, 18.72-23.98, 0.30-0.55, 0.15-0.21, 0.15-0.23 and 0.30-0.48 mg/kg for hebal tea, respectively. CONCLUSION: The metal content in the investigated tea indicated low to enhanced concentrations. Locally produced black teas recorded relatively low trace metal contents compared to the green and herbal tea samples. The most bioavailable trace metal was Mn, while Zn was most preferably bound to the residual fraction. Cadmium, Cr, Cu, Ni, Pb, and V were distributed at varied concentrations among other extractable phases. Daily consumption of the investigated tea products may expose consumers to potentially toxic metals as well as essential elements. COMPETING INTERESTS: The authors declare no competing financial interests.

A new method for assessment of sediment-associated contamination risks using multivariate statistical approach.

This paper presents the assimilation of heavy metal concentration data from sequential extraction method (SEM) with metal toxicity factors to develop and propose two new sediment quality indices modified hazard quotient (mHQ) and ecological contamination index (ECI), to predict the potential ecological risks associated with sediment contamination. Chemical speciation data of five heavy metals: cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and lead (Pb) from five coastal aquatic ecosystems of the Equatorial Atlantic Ocean were used in the assessment of the degree of heavy metal contamination. Evaluation based on ECI indicated that sediments of most aquatic ecosystems were considerably to highly contaminated. The results showed that the proposed indices are reliable, precise, and in good agreement with similar existing indices used for evaluating the severity of sediment-associated contamination by heavy metals. The principal component analysis (PCA) and factor analysis indicated that heavy metals in the benthic sediments were mostly from anthropogenic sources. •New indices - modified hazard quotient (mHQ) and ecological contamination index (ECI) - were developed for predicting sediment-associated risk adverse effects.•Newly proposed indices agree closely with the existing pollution indices.•Pollution indices reveal significant anthropogenic contamination by Cd and Pb.

Trace and major elements distribution in coastal sediment cores from Lagos Lagoon, Nigeria.

Heavy metals contamination in aquatic ecosystems has been a major concern, however, no information is available about the concentrations, depth distributions and ecological risks of heavy metals in sediments cores from microtidal lagoonal ecosystem in Lagos, Nigeria. Four sediment cores were collected using a 50 cm × 3.5 cm Wildco® hand corer. Elemental determinations were carried out using the Microwave Plasma Atomic Emission Spectrometry (4200 MP-AES) after extraction. The concentrations of heavy metals in the sediment cores indicated enhanced degree of contamination influenced by anthropogenic discharges especially industrial effluents. Vertical depth distributions indicated varied depositional periods largely controlled by increasing anthropogenic land-based activities. The remarkable metal pollution of core sediments raises the concern potential sources of metals to the lagoonal ecosystem and ecological risks to the biota, humans, and the environment. The results of elemental concentrations should be considered as baseline data for heavy metals in sediments in the region.

Toxic metals in cigarettes and human health risk assessment associated with inhalation exposure.

This study evaluated the concentrations of cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), and zinc (Zn) in 10 branded cigarettes commonly consumed in Nigeria. Chemical sequential extraction method and pseudo-total metal digestion procedure were used for extraction of metals from filler tobacco and filter samples. Samples were analyzed using flame atomic absorption spectrometry (FAAS). The filler tobacco of cigarettes had Cd, Cu, Fe, Mn, Pb, and Zn concentrations in the ranges of 5.90-7.94, 18.26-34.94, 192.61-3494.05, 44.67-297.69, 17.21-74.78, and 47.02-167.31 µg/cigarette, respectively. The minimum and maximum concentrations in the filter samples were 8.67-12.34 µg/g of Cd, 1.77-36.48 µg/g of Cu, 1.83-15.27 µg/g of Fe, 3.82-7.44 µg/g of Mn, 4.09-13.78 µg/g of Pb, and 30.07-46.70 µg/g of Zn. The results of this study showed that the concentrations of heavy metals in the filler tobacco samples were consistently higher than those obtained for the cigarette filters except for Cd. Toxic metals were largely found in the most labile chemical fractions. Moderate to very high risks are found associated with potential exposure to Cd and Pb. The carcinogenic risks posed by Cd and Pb ranged between 1.87E-02 and 2.52E-02, 1.05E-03 and 4.76E-03, respectively, while the non-carcinogenic risk estimates for Cd and Pb were greater than 1.0 (HI > 1). Toxic metals in cigarette may have significant carcinogenic and non-carcinogenic health effects associated with inhalation exposure. Continuous monitoring and regulations of the ingredients of imported and locally produced tobacco products are advocated.

Disinfection Byproducts in Drinking Water and Evaluation of Potential Health Risks of Long-Term Exposure in Nigeria.

Levels of trihalomethanes (THMs) in drinking water from water treatment plants (WTPs) in Nigeria were studied using a gas chromatograph (GC Agilent 7890A with autosampler Agilent 7683B) equipped with electron capture detector (ECD). The mean concentrations of the trihalomethanes ranged from zero in raw water samples to 950 µg/L in treated water samples. Average concentration values of THMs in primary and secondary disinfection samples exceeded the standard maximum contaminant levels. Results for the average THMs concentrations followed the order TCM > BDCM > DBCM > TBM. EPA-developed models were adopted for the estimation of chronic daily intakes (CDI) and excess cancer incidence through ingestion pathway. Higher average intake was observed in adults (4.52 × 10-2 mg/kg-day), while the ingestion in children (3.99 × 10-2 mg/kg-day) showed comparable values. The total lifetime cancer incidence rate was relatively higher in adults than children with median values 244 and 199 times the negligible risk level.

Functionalized Benzimidazole Scaffolds: Privileged Heterocycle for Drug Design in Therapeutic Medicine.

Benzimidazole derivatives are crucial structural scaffolds found in diverse libraries of biologically active compounds which are therapeutically useful agents in drug discovery and medicinal research. They are structural isosteres of naturally occurring nucleotides, which allows them to interact with the biopolymers of living systems. Hence, there is a need to couple the latest information with the earlier documentations to understand the current status of the benzimidazole nucleus in medicinal chemistry research. This present work unveils the benzimidazole core as a multifunctional nucleus that serves as a resourceful tool of information for synthetic modifications of old existing candidates in order to tackle drug resistance bottlenecks in therapeutic medicine. This manuscript deals with the recent advances in the synthesis of benzimidazole derivatives, the widespread biological activities as well as pharmacokinetic reports. These present them as a toolbox for fighting infectious diseases and also make them excellent candidates for future drug design.