Elevated Levels Of Zinc Research Articles

The oral disposition of zinc following the use of an anticalculus toothpaste containing 0.5% zinc citrate.

Zinc is retained in the mouth after use of a toothpaste containing 0.5% zinc citrate. More than one third of the dose was found to be retained after normal brushing. Elevated zinc levels were also found in plaque. Saliva zinc levels were significantly above background for at least 2 h after brushing. In-vitro experiments demonstrated that zinc can bind to the pellicle-coated tooth surface and can subsequently adsorb into saliva. Plaque can calcify to form calculus containing appreciable levels of hydroxyapatite. Zinc adsorbs to hydroxyapatite inhibiting crystal growth. Levels of zinc in plaque were found to be considerably higher than those taken up by hydroxyapatite in an in-vitro test of crystal growth inhibition indicating the potential of zinc to inhibit calculus formation.

Evaluation of Serum Zinc Level Under Malignant Condition and its Possible Implication on Improving Cell-Mediated Immunity During Cancer Progression.

BackgroundZinc is an essential trace element required for different biological functions in a living body. Evaluating its concentration and effect during malignancy is important not only to assess the disease activity but also to evaluate its role in some important biological activities like immunity.MethodsThe experiments were carried out in transplanted, chemically induced and spontaneous tumors in mice. The serum zinc concentration (SZC) was determined under malignant condition and following treatment of solid tumor with anti-cancer agents. The importance of evaluating Cu/Zn ratio (CZR) was also determined. To evaluate its role in immune response during malignancy, studies were carried out on induced tumor bearing animals.ResultsThe results showed that SZC had an inverse correlation with the progression of the disease. It was significantly reduced in all forms of malignancy, more so in spontaneous and induced forms of the disease. Extensive studies done with the solid form of induced tumor, established the importance of estimating the concentration of Zn, in addition to that of copper, in assessing the disease activity following treatment with anti-cancer agents. With regression of the tumor mass, there was a significant elevation in the SZC and depression in the serum copper concentration (SCC) compared to their levels prior to treatment. This was also reflected on the value of copper zinc ratio (CZR); with the onset of tumor regression, a significant reduction in CZR was noted in the tumor bearing animals compared to their untreated levels. As the state of ‘regression’ in the tumor mass was maintained for a considerable period of time following treatment with anti-cancer agents along with elevated zinc levels, we considered the role of zinc in controlling the tumor growth, indirectly. We observed that zinc is able to stimulate lymphocyte proliferation that may directly impact on the immune response of tumor bearing host.ConclusionsZinc appears to play a role in tumor progression and regression and in stimulating lymphocyte proliferation. It is hypothesized that supplementing zinc to malignant subjects prior to and following therapeutic intervention with anti-cancer agents could help improve immune response of the host against existing tumor.

Assessing the nature of the combined effects of copper and zinc on estuarine infaunal communities

Elevated levels of copper and zinc in sediment have been shown to adversely affect estuarine infauna. We investigated the additivity of the combined effects of copper and zinc on infaunal recolonisation through a manipulative field experiment in Orewa estuary, New Zealand, using defaunated sediment discs treated with these metals. The nature of their combined effects varied among infaunal taxa and the particular variables being examined. Additive effects were detected for species richness, for the mean log abundances of the polychaetes Prionospio sp. and Scoloplos cylindrifer and for the multivariate response of the community as a whole. Antagonistic effects were detected for the mean log abundances of total infauna and the polychaete Heteromastus sp. Characterising the potentially interactive nature of the combined effects of multiple heavy metals is essential in order to build predictive models of future environmental impacts of metal accumulation in estuarine sediments.

Increased metallothionein gene expression, zinc, and zinc-dependent resistance to apoptosis in circulating monocytes during HIV viremia

Circulating monocytes exhibit an apoptotic resistance phenotype during HIV viremia in association with increased MT expression. MTs are known to play an important role in zinc metabolism and immune function. We now show, in a cross-sectional study using peripheral monocytes, that expression of MT1 isoforms E, G, H, and X is increased significantly in circulating monocyte cells from HIV+ subjects during chronic viremic episodes as compared with uninfected subjects. This increase in expression is also observed during acute viremia following interruption of suppressive ART. Circulating monocytes from HIV+ donors were also found to have elevated zinc importer gene Zip8 expression in conjunction with elevated intracellular zinc levels in contrast to CD4(+)T-lymphocytes. In vitro HIV-1 infection studies with elutriated MDM confirm a direct relation between HIV-1 infection and increased MDM MT1 (isoform G) gene expression and increased intracellular zinc levels. A direct link between elevated zinc levels and apoptosis resistance was established using a cell-permeable zinc chelator TPEN, which reversed apoptosis resistance effectively in monocytes from HIV-infected to levels comparable with uninfected controls. Taken together, increases in MT gene expression and intracellular zinc levels may contribute directly to maintenance of an immune-activated monocyte by mediating an increased resistance to apoptosis during active HIV-1 viremia.

Evaluation of Pathogen Removal in a Solar Sludge Drying Facility Using Microbial Indicators

South East Queensland is one of the fastest growing regions in Australia with a correspondingly rapid increase in sewage production. In response, local councils are investing in more effective and sustainable options for the treatment and reuse of domestic and industrial effluents. A novel, evaporative solar dryer system has been installed on the Sunshine Coast to convert sewage sludge into a drier, usable form of biosolids through solar radiation exposure resulting in decreased moisture concentration and pathogen reduction. Solar-dried biosolids were analyzed for selected pathogenic microbial, metal and organic contaminants at the end of different drying cycles in a collaborative study conducted with the Regional Council. Although fecal coliforms were found to be present, enteroviruses, parasites, E. coli, and Salmonella sp. were not detected in the final product. However, elevated levels of zinc and copper were still present which restricted public use of the biosolids. Dilution of the dried biosolids with green waste as well as composting of the biosolids is likely to lead to the production of an environmentally safe, Class A end-product.

Synchrotron radiation analysis of possible correlations between metal status in human cementum and periodontal disease

Periodontitis is a serious disease that affects up to 50% of an adult population. It is a chronic condition involving inflammation of the periodontal ligament and associated tissues leading to eventual tooth loss. Some evidence suggests that trace metals, especially zinc and copper, may be involved in the onset and severity of periodontitis. Thus we have used synchrotron X-ray fluorescence imaging on cross sections of diseased and healthy teeth using a microbeam to explore the distribution of trace metals in cementum and adhering plaque. The comparison between diseased and healthy teeth indicates that there are elevated levels of zinc, copper and nickel in diseased teeth as opposed to healthy teeth. This preliminary correlation between elevated levels of trace metals in the cementum and plaque of diseased teeth suggests that metals may play a role in the progress of periodontitis.

Sensitivity of three unionid glochidia to elevated levels of copper, zinc and lead

In this study glochidia as most sensitive life-stage of bivalves were used to evaluate the toxicity of copper, zinc and lead. Sensitivity of three species, Anodonta anatina, Pseudanodonta complanata and Unio tumiduswere compared to copper and zinc, based on 24 and 48 h LC50s. The copper 24 h LC50 showed the lowest value (26.8 μg·L-1) for Unio tumidus glochidia. After 48 h exposure, close LC50 values, 18.9 and 19.0 μg·L-1, were recorded for A. anatina and U. tumidus glochidia, respectively. U. tumidus glochidia exhibited the highest sensitivity to zinc (48 h LC50 = 134.2 μg·L-1) followed by P. complanata (48 h LC50 = 201.6 μg·L-1) and A. anatina (48 h LC50 = 233.5 μg·L-1). Toxicity of lead to P. complanata glochidia was estimated, 24 and 48 h LC50s of lead to 374.6 and 260.8 μg·L-1, respectively. No observed effect concentrations (NOECs) for the tested metals exhibited species differences. All NOECs exceeded environmental quality standards (EQS), therefore these species are at risk only in such European freshwaters which have extreme concentration of these metals. Synergistic effect was reported for the combinations of Cu + Zn and Cu + Pb, additive effect was reported for Zn + Pb.

Heavy metal removal within pilot-scale constructed wetlands receiving river water contaminated by confined swine operations

Three parallel pilot-scale surface flow constructed wetlands were employed to investigate heavy metal removal receiving river water contaminated by swine confined-housing operations in Taiwan. Wastewater from swine operation contained elevated levels of copper and zinc due to their abundance in feed. Two macrophytes, namely cattail ( Typha latifolia ) and reed ( Phragmites australis ), were planted to observe their heavy metal removal efficiency. Significant total recoverable copper and zinc reduction for three tested wetlands were 80 and 91% for unplanted control, 83 and 92% for cattail, and 83 and 92% for reed wetland systems. Acid-soluble forms were 56 and 86% of total recoverable influent metals for copper and zinc, respectively. More bioavailable zinc was subjected to releasing back to aqueous environment. Heavy metals entering the studied systems as insoluble forms were settling from water column. Concentrations of metals were higher in the vegetated sediments than in the non-vegetated sediments. The sequential extraction results of sediments indicated that most retained metals were in less mobile fractions. Most of metal uptake by vegetation remained in root portions. Translocations of both copper and zinc for tested macrophytes were not prominent. The metal species in incoming water and metal fractionations in sediment were demonstrated as the major factors to influence plant metal levels. The performance of the studied wetland systems can comply with local water criteria rendering for further water reuse.

Carotenoids and pH of the culture medium play an important role in displaying metal stress in batch and semi-continuous cultures ofAnabaena doliolum

We analysed the responses of Anabaena doliolum to elevated levels of copper and zinc in batch and semi-continuous cultures. Approximately 10, 4 and 8 and 5-times greater inhibition in final yield of A. doliolum occurred at 1, 2 μM Cu and 2.5 and 5 μM of Zn, respectively, in semi-continuous culture in comparison to batch culture. Protein, chlorophyl a and carotenoid contents of A. doliolum showed significantly (P < 0.05) higher inhibition by test metals in semi-continuous culture than in batch culture. The greater sensitivity of different parameters of the test organism was related to the high metal content of the cells grown in semi-continuous system. Moreover, enhancement of pH of the culture suspension in batch culture showed a negative relationship with metal accumulation, and therefore with toxicity. This was due to decrease in free ionic concentrations of test metals. Carotenoids acted as a metal detoxifying agent by minimizing metal-induced inhibition in batch culture as was evident from its negative relationship with metal toxicity.

Environmental tritium contamination from a gaseous tritium light device maintenance facility

An investigation was undertaken in relation to the contamination of a facility used for the servicing and refurbishment of gaseous tritium light devices. While it is generally accepted that there is minimal exposure hazard from a broken gaseous tritium light source after the tritium gas has dispersed, environmental tritium contamination displaying 'particulate' like characteristics was observed during the radiological assessment of the facility in 2003. The contamination is considered to be associated with zinc sulphide phosphor residues from damaged tritium light sources. A subsequent environmental tritium survey was conducted in 2007, in the vicinity of the affected building to determine the extent of contamination and impact on current and future occupancy and land use application. The survey was conducted by measuring both soil non-aqueous tritium and soil pore water tritium concentration. Zinc concentration, from the zinc sulphide phosphor, was also measured for the same samples to assess correlation between tritium contamination activity and the identified source material. Greater than 97% of the soil non-aqueous tritium results were observed to be less than the derived tritium residential screening level of 8.5 Bq ⋅ kg-1 , and that soil pore water tritium concentrations had decreased from 8 MBq ⋅ L-1 to less than 2 kBq ⋅ L-1 over a period of 5 years. Elevated elemental zinc levels in the upper surface soils correlated with increased non-aqueous tritium concentration. Ground water tritium concentrations ranged from 3 Bq ⋅ L-1 to 20 Bq ⋅ L-1 , indicating leakage of tritium contaminated water to local aquifer systems. Natural attenuation and dilution processes have reduced environmental tritium contamination levels over a period of 5 years since the introduction of new contamination control policies and operational changes at the facility.

Selective Inhibition of Mitogen-Activated Protein Kinase Phosphatases by Zinc Accounts for Extracellular Signal-Regulated Kinase 1/2-Dependent Oxidative Neuronal Cell Death

Oxidative stress induced by glutathione depletion in the mouse HT22 neuroblastoma cell line and embryonic rat immature cortical neurons causes a delayed, sustained activation of extracellular signal-regulated kinase (ERK) 1/2, which is required for cell death. This sustained activation of ERK1/2 is mediated primarily by a selective inhibition of distinct ERK1/2-directed phosphatases either by enhanced degradation (i.e., for mitogen-activated protein kinase phosphatase-1) or as shown here by reductions in enzymatic activity (i.e., for protein phosphatase type 2A). The inhibition of ERK1/2 phosphatases in HT22 cells and immature neurons subjected to glutathione depletion results from oxidative stress because phosphatase activity is restored in cells treated with the antioxidant butylated hydroxyanisole. This leads to reduced ERK1/2 activation and neuroprotection. Furthermore, an increase in free intracellular zinc that accompanies glutathione-induced oxidative stress in HT22 cells and immature neurons contributes to selective inhibition of ERK1/2 phosphatase activity and cell death. Finally, ERK1/2 also functions to maintain elevated levels of zinc. Thus, the elevation of intracellular zinc within neurons subjected to oxidative stress can trigger a robust positive feedback loop operating through activated ERK1/2 that rapidly sets into motion a zinc-dependent pathway of cell death.

English

Granular mine waste are generated from the extraction and beneficiation of lead/zinc minerals. The fine gravel waste, commonly known as chat, contains elevated levels of lead, zinc and cadmium which can result in potentially serious human health and ecological concerns. With the use of chat in a variety of applications such as road construction, there is an increased environmental concern due to the potential leachability of lead (Pb), cadmium (Cd) and zinc (Zn) at high concentrations. In this study, we examine the release of these three metals from raw chat and its reuse products, mainly cold-mix asphalt (CMA) and hot-mix asphalt (HMA), to determine the environmental stability of the materials under different environmental conditions. The leachability of metals was evaluated using extraction tests including the toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP) and deionized water extraction procedure (DWEP). In addition, the relative bioaccessability of the metals was determined by the relative bioaccessability leaching procedure (RBLP) tests. Based on the conducted leaching tests, it was observed that all the three samples failed the TCLP test. The Cd and Pb concentrations in the TCLP extracts were higher than the mandated TCLP limits for leaching from wastes. The TCLP extracts of CMA and HMA samples were found to be less than the limit for Cd, but higher for Pb. The experimental data also showed that the concentrations of Cd and Pb in the SPLP extracts were less than the National Drinking Water Primary Standards of 0.005 mg/L and 0.015 mg/L, respectively. This indicated the suitability of the mine tailing and its reuse products for beneficial applications. The percent bioaccessible metal followed the order: raw chat < HMA < CMA, probably due to its smaller particle size (< 250 µm), compared to the particle sizes of CMA and HMA tested (< 2 mm). The data indicated that while the use of chat in asphalt is environmentally safe, care should be taken as metals could leach in significant concentrations when placed in moist environments for longer duration.

Sublethal haematological effects of zinc on the freshwater fish, Heteroclarias sp. (Osteichthyes: Clariidae)

-1 ) of zinc in water for a period of fifteen (15) days. Three groups of ten fish were subjected to serial dilutions of the stock solution of zinc of 0 (control), 5.0 and 10.0 mg L -1 in three large plastic bowls of 60 litres capacity by the semistatic (renewal) method. At the end of the 15 days exposure period, blood samples were taken from the control and experimental fish. Blood was assayed for selected haematological parameters (haematocrit, haemoglobin, red blood cell counts, white blood cell counts, differential white blood cell counts, erythrocyte sedimentation rate, total plasma protein and plasma glucose concentration). The derived haematological indices of mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were calculated. Sublethal concentrations (5.0 and 10.0 mg L -1 ) of zinc caused a dose dependent decrease in haemoglobin values, coupled with a decrease in haematocrit values and red blood cell counts are obvious indication of anemia of the norm chronic type. The total white blood cell counts and the differential white blood cell counts were decreased except for the lymphocytes in which there was a slight increase. Plasma level of protein and glucose were also lower in the exposed fish when compared to the control. The haematological indices MCHC, MCH and MCV were also lowered. In conclusion, the changes observed indicate that haematological parameters can be used as an indicator of zinc related stress in fish on exposed to elevated zinc levels.

English

&nbsp; Laboratory study was undertaken to evaluate some haematological changes resulting from the exposure of a freshwater fish,&nbsp;Heteroclarias&nbsp;sp. to sublethal concentrations (5.0 and 10.0 mg L-1) of zinc in water for a period of fifteen (15) days. Three groups of ten fish were subjected to serial dilutions of the stock solution of zinc of 0 (control), 5.0 and 10.0 mg L-1&nbsp;in three large plastic bowls of 60 litres capacity by the semistatic (renewal) method. At the end of the 15 days exposure period, blood samples were taken from the control and experimental fish. Blood was assayed for selected haematological parameters (haematocrit, haemoglobin, red blood cell counts, white blood cell counts, differential white blood cell counts, erythrocyte sedimentation rate, total plasma protein and plasma glucose concentration). The derived haematological indices of mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were calculated. Sublethal concentrations (5.0 and 10.0 mg L-1) of zinc caused a dose dependent decrease in haemoglobin values, coupled with a decrease in haematocrit values and red blood cell counts are obvious indication of anemia of the norm chronic type. The total white blood cell counts and the differential white blood cell counts were decreased except for the lymphocytes in which there was a slight increase. Plasma level of protein and glucose were also lower in the exposed fish when compared to the control.&nbsp; The haematological indices MCHC, MCH and MCV were also lowered. In conclusion, the changes observed indicate that haematological parameters can be used as an indicator of zinc related stress in fish on exposed to elevated zinc levels. &nbsp; Key words:&nbsp;Zinc, haematology, anaemia, glucose, protein,&nbsp;Heteroclarias,Nigeria.

Accumulation of Zinc in Human Atherosclerotic Lesions Correlates With Calcium Levels But Does Not Protect Against Protein Oxidation

Oxidized lipids and proteins, as well as decreased antioxidant levels, have been detected in human atherosclerotic lesions, with oxidation catalyzed by iron and copper postulated to contribute to lesion development. Zinc has been postulated to displace iron from critical sites and thereby protect against damage. In this study, metal ion and protein oxidation levels were quantified in human carotid and abdominal artery specimens containing early-to-advanced lesions, to determine whether zinc concentrations correlate inversely with iron levels and protein oxidation. Metal ions were quantified by EPR and inductively coupled plasma mass spectroscopy. Native and oxidized protein side-chains were quantified by high-performance liquid chromatography. Elevated levels of zinc ( approximately 6-fold) were detected in advanced lesions compared to healthy tissue or early lesions. Zinc did not correlate negatively with iron or copper levels suggesting that zinc does not displace these metal ions. Highly significant positive correlations (P<0.005) were detected between zinc and calcium levels. Zinc did not correlate with low iron levels and reduced protein oxidation. These data indicate that zinc does not prevent protein oxidation in advanced lesions. The reported protective effect of zinc accumulation is proposed to be associated with lesion calcification.

Clean Chip Residual: A Substrate Component for Growing Annuals

A study was conducted at Auburn University in Auburn, AL, and the U.S. Department of Agriculture–Agricultural Research Service, Southern Horticultural Laboratory in Poplarville, MS, to evaluate clean chip residual (CCR) as an alternative substrate component for annual bedding plant production. Clean chip residual used in this study was processed through a horizontal grinder with 4-inch screens at the site and was then processed again through a swinging hammer mill to pass a 3/4- or 1/2-inch screen. Two CCR particle sizes were used alone or blended with 10% (9:1) or 20% (4:1) peatmoss (PM) (by volume) and were compared with control treatments, pine bark (PB), and PB blends (10% and 20% PM). Three annual species, ‘Blue Hawaii’ ageratum (Ageratum houstonianum), ‘Vista Purple’ salvia (Salvia ×superba), and ‘Coral’ or ‘White’ impatiens (Impatiens walleriana), were transplanted from 36-cell (12.0-inch3) flats into 1-gal containers, placed on elevated benches in a greenhouse, and hand watered as needed. Ageratum plants grown at Auburn had leaf chlorophyll content similar or greater than that of plants grown in PB. There were no differences in salvia; however, impatiens plants grown in PB substrates at Auburn had less leaf chlorophyll content than those grown in CCR. There were no differences in ageratum, salvia, or impatiens leaf chlorophyll content at Poplarville. There were no differences in growth indices (GI) or shoot dry weight (SDW) of ageratum, while the largest salvia was in PB:PM and the largest impatiens were in PB-based substrates at Auburn. The GI of ageratum at Poplarville was similar among treatments, but plants grown in 4:1 1/2-inch CCR:PM were the largest. Salvia was largest in 4:1 CCR:PM and PB:PM, and although there were no differences in GI for impatiens at Poplarville, the greatest SDW occurred with PB:PM. Foliar nutrient content analysis indicated elevated levels of manganese and zinc in treatments containing CCR at Auburn and PB at Poplarville. At the study termination, two of three annual species tested at both locations had very similar growth when compared with standard PB substrates. This study demonstrates that CCR is a viable alternative substrate in greenhouse production of ageratum, salvia, and impatiens in large containers.

Increased Uptake of Zinc in Malignant Cells is Associated with Enhanced Activation of MAPK Signalling and P53-Dependent Cell Injury

Excess intracellular zinc has been demonstrated to be responsible for cell injury and cell death in various experimental as well as clinical models. While the cells possess a system of mechanisms regulating intracellular zinc homeostasis, their saturation by acutely increased zinc levels or by a sustained exposure to elevated zinc levels results in liberation of free zinc stores within the cells and ultimate cell damage and cell death. Here we report that in Hep-2 malignant cells enhanced uptake of zinc causes activation of mitogen-activated protein kinase (MAPK) signaling with resulting p53-dependent cell injury which can be significantly prevented by specific p53 inhibition and by prevention of oxidative stress. Our observations are consistent with the view that subacutely increased intracellular free zinc levels stimulate via oxidative stress p53-dependent pathways which are responsible for the final cell damage in tumor cells.

The effect of superoxide dismutase deficiency on zinc toxicity in Schizosaccharomyces pombe

Zinc is a metal which is a cofactor in many enzymes and a structural element in zinc finger motifs those are important in relation between DNA and regulator proteins. Little is known about uptake, distribution, toxicity and detoxification of zinc ions in cells. In this study, zinc toxicity and detoxification levels have been compared in wild type and Cu/Zn superoxide dismutase mutant (sod1Delta) cells of the fission yeast Schizosaccharomyces pombe. We evaluated the toxic levels of zinc, total zinc content, lipid peroxidation levels and catalase activities for both strains which were grown in medium containing different concentrations of zinc. sod1Delta mutant showed important growth retardation and has higher lipid peroxidation and catalase activities than wild type. Cu/Zn superoxide dismutase (SOD1) activity of wild type cells was markedly increased when they were treated with elevated levels of zinc. SOD1 mRNA level also significantly increased when the cells treated with higher concentrations of zinc. These results indicate that the mutant cells were more sensitive to zinc stress and seemed to have more oxidative intracellular environment than wild type cells. Our results support the idea that superoxide dismutase is an important factor for zinc detoxification in eukaryotes.

Histidine ligands in bacterial metallothionein enhance cluster stability

The cyanobacterial metallothionein (MT) SmtA is the prototype for bacterial MTs and protects against elevated levels of zinc. In contrast to mammalian MTs, bacterial MTs coordinate to metal ions not only via cysteine sulfurs, but unusually for MTs, also via histidine nitrogens. To investigate whether histidine coordination in these metal-sulfur clusters provides advantages over S-coordination only, we mutated the two metal-binding histidine residues in the cyanobacterial MT SmtA from Synechococcus PCC7942 to cysteines. We show that the mutant proteins are still capable of binding up to four zinc ions as is the wild-type protein. However, the mutations perturb protein folding and metal-binding dynamics. Interestingly, several homologues of SmtA also show variations in these two residues. We conclude that histidine residues in Synechococcus PCC7942 SmtA have a stabilising effect due to electrostatic interactions that impact on protein folding and metal cluster charge, and are involved in fine-tuning the reactivity of the bound metal ions.

Iron hydroxide-coated sand filter for household drinking water from roof-harvested rainwater

This paper reports the performance of iron hydroxide-coated sand medium in removing bacteria and heavy metals from roof-harvested rainwater. In long-duration column tests (15 cm × 2.5 cm ID columns; empty bed contact time 15 min) employing roof-harvested rainwater, total coliform and faecal coliform removal ranged from 97% to >99%, and effluent turbidity remained below 2.0 NTU up to 500 bed volumes (BV). In comparison, bacterial removal by uncoated sand medium was always below 21%. Further column tests duplicating the use pattern of household water purification devices (daily input of 10 BV) indicated that intermittent use of the medium did not affect its performance, with bacterial removal remaining in the same range of 97–99% for 500 BV (50 d). Long-duration column tests conducted using a roof runoff (galvanised iron roof) with elevated levels of heavy metals, lead and zinc, showed that the medium is capable of effectively removing bacteria and heavy metals simultaneously for 600 BV, with effluent lead and zinc levels below the WHO guideline values for drinking water. Influent pH did not affect the bacterial removal in the pH range studied (pH 6.0–9.0). No leaching of iron from the sand was noticed for this pH range. The study showed the potential of iron hydroxide-coated sand as a sorptive filter medium for use in simple home water purification devices for treatment of roof-harvested rainwater which is generally contaminated by microorganisms and heavy metals.