Total and bio-accessible toxic metals in low-cost children toys sold in major markets in Ibadan, South West Nigeria

Toxic metals are usually added to children's toys to improve/impact some intrinsic properties such as colour which attracts children. Some of the toxic metals have life-threatening potentials on children when ingested. There is no specific legislation in Nigeria that monitors and regulates limits of such metals in toys. This study assessed total and bio-accessible concentrations of Pb, Cd, Cr, Ni, and Mn in imported low-cost children's plastic toys sold in popular markets in Ibadan, Nigeria. A total of 22 different toys were purchased and subjected to an indicative test for the presence of polyvinyl chloride (PVC) following the Beilstein method as well as analysing for total recoverable metals and migrated fractions into simulated saliva and gastric environments. Toy samples were crushed, ashed, and dissolved with dilute nitric acid for total recoverable metals while migration studies were carried out using simulated saliva and gastric environments to check bio-accessible fractions that could leach into the human system. Metals in all extracts were determined using flame atomic absorption spectrophotometric technique. The indicative PVC test showed 12 samples positive to PVC and 10 tested negative. Total recoverable metal concentrations (mg/kg) ranged as follows: Pb: Below Detection Limit (BDL) - 4838, Cd: BDL - 44.9, Cr: 0.331–79.8, Ni: 0.273–59.1 and Mn: 0.205–31.0 with Pb and Cr having 18 and 14% of samples higher than EU limits of 90 and 60 mg/kg. Bio-accessible concentrations in artificial saliva were: Pb: BDL - 42.4, Cd: BDL-0.450, Ni: BDL-1.40 and Mn: BDL-0.058 with Pb higher in 70% of samples compared to 2.0 mg/kg migrated EU limit while other metals were within the limits. Furthermore, metal concentrations that migrated to gastric environment were: Pb: 8.24–50.3, Cd: BDL-0.057, Ni: 0.103–1.96 and Mn: BDL-1.37 with Pb in 100% of samples higher than 2.0 mg/kg EU migrated limit. Chromium migration in both environments was BDL. The results of this study suggest that toxic metal contents are present in both PVC and non-PVC made toys, but higher in PVC containing toys. Though the calculated hazard index for health risk assessment of heavy metals was < 1 for all metals, Pb concentration in both total recoverable extract and saliva and gastric environments seem to be problematic and constant monitoring and regulation are required

Indoor Environmental Health Assessment in Eco-Building and Its Case Study

It is necessary to consider all aspects of environmental factors when assessing the health impact of an eco-building environment on its occupants. However, the multi-criteria and imprecise nature of the indoor-environment in the eco-buildings has caused difficulties in quantifying the indoor environmental pollution level. This paper describes the optimal classification and priority weight methods, which are particularly useful for assessing the indoor environmental quality (IEQ) of an eco-building to demonstrate its innovative applications. The analytic hierarchy process (AHP) was used to set up the strategic decision-making evaluation system for computing the indoor environment index (IEI) risk ranking of eco-buildings. Combined with this, a Microsoft Delphi-based IEQ intelligent forecasting software simulations package was developed, and the innovative application of indoor environmental comprehensive assessment was verified by a case study in Shanghai. The evaluation result was analyzed by the priority weight methods and the AHP decision-making system noted above. This health assessment method and system provides an innovative way for the indoor environment risk evaluation of eco-buildings and is helpful to standardize the local building market

Fecal sludge management : Insights from selected cities in Sub-Saharan Africa

Recent studies have shown that over half of the world’s population lives in urban areas, with the number of people living in slums growing by over 20 million per year and people living in urban areas lacking access to adequate sanitation. This study presents a review of the challenges facing fecal sludge management (FSM). A globally relevant issue in developing urban centers, especially in selected developing countries in West Africa was discussed. Some key findings of the review are that effective sanitation in developing areas depends on the chain of services and that one of the largest problems in sanitation is FSM. This study presents the initial steps toward understanding the main issues involving FSM in developing cities of West Africa. Results are intended to be used as a support for decisions on policies, strategies for FSM, and investments for improved treatment facilities in the region. The study suggests that governments and private sector organizations should develop adequate measures for handling fecal sludge

Účinná adsorpce reaktivní černé 5 na hybridní chitosanem aktivované uhlíkové korálky impregnované hexadecylaminem

Předmětem této studie je příprava kompozitních pelet složených z aktivovaného uhlíku a chitosanu upraveného hexadecylaminem (HDA) a využití těchto pelet k adsorpci aniontového černého barviva RB5 ve vodném prostředí. Pelety, které byly připraveny u 0,2 g aktivovaného uhlíku 0,04 g HDA, vykázaly nejvyšší účinnost při adsorpci. Pelety byly charakterizovány infračervenou spektroskopií (FTIR) a elektronovým skenovacím mikroskopem (SEM). V sérii experimentů byla vyšetřována nutná dávka adsorbentu, pH, doba kontaktu, což jsou parametry významně ovlivňující účinnost adsorpce. Získané údaje byly v souladu s Freundlichovým modelem (R2=0,994) a modelem pseudo-druhého řádu (R2=0,994). Dále bylo zjištěno, že adsorpce RB5 na peletách závisí na pH a maximální Langmuirovy adsorpční kapacity bylo dosaženo při pH=4. Dále bylo též ověřeno, že syntetizované pelety je možné regenerovat a opakovaně využít pro adsorpci.In this study, hexadecylamine (HDA) impregnated chitosan-powder activated carbon (Ct-PAC) composite beads were successfully prepared and applied to adsorption of the anionic dye reactive black 5 (RB5) in aqueous solution. The Ct-PAC-HDA beads synthesized with 0.2 g powdered activated carbon (PAC) and 0.04 g HDA showed the highest dye removal efficiency. The prepared beads were characterized using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Various adsorption parameters, i.e., adsorbent dosage, pH, and contact time, which affect the adsorption performance, were studied in a series of batch experiments. The obtained adsorption data were found to be better represented by Freundlich (R2 = 0.994) and pseudo-second-order (R2 = 0.994) models. Moreover, it was ascertained that the adsorption of RB5 onto Ct-PAC-HDA beads is pH-dependent, and the maximum Langmuir adsorption capacity (666.97 mg/g) was observed at pH 4. It was also proved that Ct-PAC-HDA beads were regenerable for repeated use in the adsorption process

Impact of Antibiotics Pretreatment on Bioelectrochemical CH₄ Production

Methane (CH₄)-producing bioelectrochemical systems (BES) are an attractive way to store excess renewable electricity and captured CO₂. Studies have suggested that methanogenesis via direct electron uptake from a biocathode is more energetically efficient than hydrogenotrophic methanogenesis. However, mechanisms and key microorganisms involved in direct electron uptake remain unclear, primarily because of H₂ produced by bacteria or extracellular hydrogenases in the system. In an attempt to minimize biological H₂ production and enrich for methanogens that could efficiently convert electrons from the cathode surface to CH₄, cathode chambers were pretreated with antibiotics targeting bacteria. We found that antibiotics pretreatment effectively reduced the proportion of H₂-producing bacteria and H₂-utilizing methanogens associated with the biocathode biofilm, and significantly promoted growth of acetoclastic methanogens from the genera Methanosarcina and Methanosaeta, several of which are known to participate in direct interspecies electron transfer. This shift in microbial community structure corresponded with 14%–36% higher cathode capture efficiencies. These results suggest that suppression of H₂ production by antibiotics pretreatment could be a promising way to enrich for methanogens that can efficiently transform electrons from a biocathode into CH₄

Citrate-Capped AuNP Fabrication, Characterization and Comparison with Commercially Produced Nanoparticles

Gold nanoparticles (AuNPs) were synthesized using citrate reduction, also known as the Turkevich method. The AuNPs were compared with the commercially available product and later subjected to characterization. The AuNPs were 13 nm in diameter with a 2.7 &times; 108 M&minus;1cm&minus;1 extension coefficient. The calculated concentration was 5.1 nM through the Beer&ndash;Lambert law using UV&ndash;vis absorbance spectra. Further detailed characterization was applied, such as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), elemental analysis using electro and DLS instruments, energy-dispersive X-ray spectroscopy (EDS), XRD, and Zeta potential. The synthesized AuNPs had a higher UV-absorbance peak of 0.93 in comparison to commercially available nanoparticles at 5.8 identical conditions. The characterization confirmed successful fabrication of colloidal-citrate-capped AuNPs and their dispersed and aggregated state with induced salt concentration. The shape and morphology were confirmed through XRD, showing a face-centered cubic lattice of {111}, confirmed at 38.1 round shape, and a crystalline lattice. AuNPs tend to be applied in sensing, detection, drug delivery, pharmaceuticals, and other applications in the environment and materials. Other applications include environmental contaminant detection, colorimetric sensors, antimicrobial applications, biosensing and drug delivery, tissue engineering, nanomedicines, optoelectronics, and catalysts

Citrate-Capped AuNP Fabrication, Characterization and Comparison with Commercially Produced Nanoparticles

Gold nanoparticles (AuNPs) were synthesized using citrate reduction, also known as the Turkevich method. The AuNPs were compared with the commercially available product and later subjected to characterization. The AuNPs were 13 nm in diameter with a 2.7 × 108 M−1cm−1 extension coefficient. The calculated concentration was 5.1 nM through the Beer–Lambert law using UV–vis absorbance spectra. Further detailed characterization was applied, such as scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), elemental analysis using electro and DLS instruments, energy-dispersive X-ray spectroscopy (EDS), XRD, and Zeta potential. The synthesized AuNPs had a higher UV-absorbance peak of 0.93 in comparison to commercially available nanoparticles at 5.8 identical conditions. The characterization confirmed successful fabrication of colloidal-citrate-capped AuNPs and their dispersed and aggregated state with induced salt concentration. The shape and morphology were confirmed through XRD, showing a face-centered cubic lattice of {111}, confirmed at 38.1 round shape, and a crystalline lattice. AuNPs tend to be applied in sensing, detection, drug delivery, pharmaceuticals, and other applications in the environment and materials. Other applications include environmental contaminant detection, colorimetric sensors, antimicrobial applications, biosensing and drug delivery, tissue engineering, nanomedicines, optoelectronics, and catalysts