Low Levels Of Metals Research Articles

Immediate one-step lime precipitation process for the valorization of winery wastewater to agricultural purposes.

The winery wastewater (WW) of the Village of Vidigueira, in south of Portugal, presented an acid pH (4.26 ± 0.029), a high content of chemical oxygen demand (COD = 3236 ± 30.43 mg L-1), turbidity (160.0 ± 7.68 NTU), total P (155.5 ± 6.36 mg L-1) K (100.5 mg L-1), and low level of metals: Pb, Cd, Cu, Ni, Mn, Fe, Zn. The K and the total P content could make them attractive from an agricultural point of view. However, the high turbidity biochemical oxygen demand (BOD5 = 1266.7 ± 208.7 mg O2 L-1)fecal coliforms (45 ± 29.8 ufc/100 mL) and toxicological total phenols 13.239 ± 3.007 mg galic acid L-1 is the main limiting parameters. By using 5 g L-1 oflime solution, the best reactional conditions are achieved: pH = 12 with a minimum volume of the produced sludge's, 33.5 ± 4.92 mL L-1. These reactional conditions allow reaching high removal levels of BOD5, turbidity, total P, and total phenols: 77.9, 98.7%, 87.1%, and 99.9%, respectively. Simultaneously, the fecal coliforms and Enterococcus are 100% eliminated. The precipitate obtained is rich in calcium (2.7891 ± 0.4350 mg Ca kg-1) organic matter (10.05 ± 0.11%), P (895.0 ± 35.4 mg P2O5 kg-1), and K (990.0 ± 84.9 mg K2O kg-1). During carbonatation reactions, the pH (7.46) and electrical conductivity (EC) (1.805 dS m-1) decreased spontaneously while the Ca2+, K+, and F- kept high: 426.53 mg L-1, 240.53 mg L-1, 176.03 mg L-1, respectively.

GINGER AND TEMULAWAK BASED HERBAL TEA AS POTENTIAL FUNCTIONAL DRINK PRODUCTS IN THE ERA OF COVID-19

To optimize the benefits of herbal processed products, especially in the era of the COVID-19 pandemic, an evaluation of the antioxidant and antimicrobial functional properties of herbal teas has been carried out. The ginger and temulawak herbal tea products in this study showed the quality that met the qualifications of the Indonesian National Standard (SNI) 3836:2013, with low levels of metal and microbial contamination and high antioxidant and antimicrobial activity against Escherichia coli and Salmonella Typhimurium. In general, the ginger and temulawak teas produced have a distinctive taste, aroma, color, and texture, with a water content of 7.26-7.61%, ash 6.12-6.71%, water-soluble ash 95.48-97.01%, acid insoluble ash 0.160-0.275%, crude fiber 4.63-14%, phenolic 66.15– 95.58%, flavonoids 36.53–67.10%. © 2021, Rasayan Journal of Chemistry, c/o Dr. Pratima Sharma. All rights reserved.

Heavy metal levels in water, brown algae (Cystoseira barbata), and eelgrass (Zostera marina) from the Southern Black Sea coast of Bulgaria

The heavy metals concentration in algae and marine water can be used as a bioindicator of an ecosystem pollution. In the present study, we determined the levels of the elements As, Pb, Cd, Hg, Mn, Zn, and Al in brown algae of the species Cystoseira barbata (Agardh, 1820), eelgrass Zostera marina (Linnaeus, 1753) and also in cooled seawater. The samples were collected during the summer period of 2020 from the region of the Southern Bulgarian Black Sea coast. Our results showed low levels of heavy metals in seawater and much higherin the studied plant species, especially of aluminum in brown algae.

Quality and safety of meat from wild boar hunted in Molise region

A study was carried out to evaluate meat quality traits and heavy metals content of longissimus thoracis muscle from wild boar of different estimated live weight (50, 70, 100 kg; n = 25, 24, 18, respectively), sex and hunting area of Molise region. Meat quality data were analysed by GLM, live weight and sex were the main factors, for heavy metals the hunting area was also included. Neither live weight nor sex affected pH, colour, vitamin E and total lipid. Cholesterol was tendentially affected by live weight and sex. Collagen content was affected only by sex. Lighter boars showed a higher content (p<.05) of polyunsaturated fatty acid (PUFA), n − 6 and n − 3 PUFA, and PUFA/SFA ratio (p<.05) compared to other weight classes. Lighter boars had a better atherogenic index compared to boars of intermediate weight. Compared to females, males (M) had higher n − 3 PUFA and a lower n − 6/n − 3 ratio (p<.05). Weight, sex and hunting area did not affect cadmium (0.001 mg/kg), lead (0.011–0.026 mg/kg), copper (0.696–1.151 mg/kg) and manganese (0.083–0.130 mg/kg) levels. Chromium was affected by sex (M: 0.072 mg/kg; p=.012). Nickel (Ni) was higher (p<.01) in the heaviest boars (0.035 mg/kg) than the other weight classes (0.017 mg/kg). Significant differences between the two areas were found for Ni content, interactions (p<.01) were detected among all factors. In conclusion, lighter boars showed a better meat nutritional quality. The low content of heavy metals in the meat indicates a low level of anthropogenic pollution of the areas under study. Highlights Meat from younger boars showed a better meat nutritional quality. Low levels of heavy metals in meat indicates a low level of anthropogenic pollution of the studied areas.

Assessment of Pollutants in Soils and Groundwater from the Coastal Plain of Paraíba do Sul River Delta, RJ, Brazil

In developing countries, the quality of the available freshwater is deteriorating mainly due to pollution. Underground water bodies are important resources, taking into account that they are usually more isolated and also protected from anthropogenic influence. Within this context, the present study aimed to assess trace metals, nitrate and organic contaminants in groundwater and soils from 10 bore wells located at the coastal plain of the Paraíba do Sul river delta. Groundwater of the study area revealed elevated concentrations of arsenic, iron, manganese and barium, surpassing the limits established by Brazilian legislation as well as the limits established by other regulatory agencies. As, Fe and Ba reached concentrations as high as 242.70, 31 919 and 4.041 µg.l-1 in groundwater. Despite the elevated values, results suggested a reducing environment and the contaminants appear to have a natural geogenic origin, which is corroborated by past studies in the same area. Soils of the aquifer presented low levels of trace metals, corroborating the hypothesis of geogenic contamination in groundwater. No significant differences among the bore wells were observed regarding trace metals in soils, and concentrations found in the present study were much lower than the ones found in impacted aquifers around the world. No PCB's were detected in groundwater or soils. Nitrate concentrations in groundwater were within the limits recommended by Brazilian legislation.

False profile view is independently associated with serum metal levels in patients with metal-on-metal hip arthroplasty.

Elevated levels of serum metal ions can be found in some patients with metal-on-metal (MoM) hip replacements. This study seeks to identify whether there is a significant association between the contact patch to rim distance (CPRD) and the anterior center edge angle (ACEA), respectively, and serum cobalt (Co) and chromium (Cr) levels in patients treated with unilateral MoM hip replacements by using standing anteroposterior and false profile view radiographs. This is a retrospective analysis on 53 patients with either unilateral ReCap or M2a-Magnum MoM hip replacements operated in 2006 or 2007. Univariate linear regression and multivariable linear regression (MLR) analyses were performed using the CPRD and ACEA along with risk factors for elevated serum levels of Co and Cr previously suggested in the literature as explanatory variables. Serum Co and Cr were measured using inductively coupled plasma mass spectrometry. The MLR model showed that the same three variables (gender, CPRD and ACEA) were significantly associated with serum levels of both Co and Cr explaining approximately half of the variation. A univariate analysis showed a polynomial association between both anteversion angle and the ACEA with serum levels of Co and Cr. The vertex of the polynomial function was located at approximately 20° and 40°, respectively. Gender, CPRD and ACEA are independently associated with serum levels of Co and Cr. Both ACEA and anteversion angles have optimae associated with low serum metal levels which may be useful for post-surgery evaluation of cup positioning.

Assessment of heavy metals in Hibiscus sabdariffa calyces and Moringa oleifera leaves collected from different areas in Tanzania

Medicinal plants are known in prevention and curing of diseases. Contamination of medicinal plants by heavy metals is one of the factors affecting quality of medicinal products from medicinal plants. Heavy metals may enter the edible and medicinal plants through contaminated environment such as water bodies, air or soil. Hibiscus sabdariffa calyces and Moringa oleifera leaves are used in Tanzania as nutritional and disease-remedial herbal drinks. This study assessed heavy metal contamination of Hibiscus sabdariffa calyces and Moringa oleifera leaves collected from Dodoma region (Vikonje, Msanga, Nzuguni A and Nzuguni B village), Pwani region (Kongowe and Chalinze village) and Shinyanga region (Mwime village). Lead, arsenic, chromium, cadmium and mercury were analyzed by Atomic Absorption Spectrometry. Microsoft excel 2010 software were used to analyze the means of heavy metal concentrations. Levels of chromium in the calyces and leaves of H. sabdariffa and M. oleifera ranged between 0.029-0.221 ppm and 0.019-0.088 ppm respectively while Arsenic was 0.096-0.204 ppm and 0.096-0.219 ppm, respectively. Mercury and Lead were found only in leaves of M. oleifera, mercury was between 0.017 ppm and 0.042 ppm and lead was 0.056 ppm. Cadmium was not detected in all plant materials. The concentrations of heavy metals in the selected samples were statistically significant at (P˂0.05). M. oleifera leaves and H. sabdariffa calyces, collected from different regions, had the low levels of heavy metals than recommended limits provided by the Tanzania Medicine and Medical Devices Authority (TMDA) and WHO.

Insights into the effects of Zn exposure on the fate of tylosin resistance genes and dynamics of microbial community during co-composting with tylosin fermentation dregs and swine manure.

Though heavy metals are widely reported to induce antibiotic resistance propagation, how antibiotic resistance changes in response to heavy metal abundances remains unclearly. In this study, the tylosin fermentation dregs (TFDs) and swine manure co-composting process amended with two exposure levels of heavy metal Zn were performed. Results showed that the bioavailable Zn contents decreased 2.6-fold averagely, and the removal percentage of total tylosin resistance genes was around 23.5% after the co-composting completed. Furthermore, the tylosin resistance genes and some generic bacteria may exhibited a hormetic-like dose-response with the high-dosage inhibition and low dosage stimulation induced by bioavailable Zn contents during the co-composting process, which represented a beneficial aspect of adaptive responses to harmful environmental stimuli. This study provided a comprehensive understanding and predicted risk assessment for the Zn-contaminate solid wastes deposal and suggested that low levels of Zn or other heavy metals should receive more attention for their potential to the induction of resistance bacteria and propagation of antibiotic resistance genes.

An eco-friendly approach to textile and tannery wastewater treatment using maghemite nanoparticles (γ-Fe2O3-NPs) fabricated by Penicillium expansum strain (K-w)

Wastewater treatment is one of the vital solutions to the global water shortage and many related environmental problems. The present study aimed at biosynthesizing maghemite nanoparticles (γ-Fe2O3-NPs) using Penicillium expansum (K-w) for the purpose of wastewater treatment. The γ-Fe2O3-NPs resultant was characterized using fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), dynamic light scattering (DLS), and X-ray photoelectron spectroscopy (XPS). The maghemite nanoparticles capacity to mediate decolorization and degradation of textile and tanning wastewater effluents was investigated. Results verified that the successful synthesis of spherical shaped Fe2O3-NPs of 15.0–66.0 nm size, with XRD peaks that match the cubic structure of the γ-Fe2O3. XPS analysis confirmed the presence of iron as Fe2O3. Decolorization and degradation analyses indicated that γ-Fe2O3-NPs are effective biocatalysts for dye degradation under dose- and time-dependent manner. The highest decolorization gain (89 %–90 %) occurred after 6.0–8.0 h of incubation at 1.0 mg mL-1 of γ-Fe2O3-NPs. Quality of the treated textile wastewater was improved, as indicated by the reduction in chemical oxygen demand (COD), total dissolved solids (TDS), and total suspended solids (TSS) by 86.8, 71.8, and 89.3 %, respectively. GC–MS results showed the complete disappearance or reduction of peaks, or peak areas in treated textile wastewater in comparison with the untreated samples. In addition, treatment of tanning wastewater with γ-Fe2O3-NPs has also resulted in decolorization, as well as reduction in COD, TDS, and TSS levels by 93.1, 40.5, and 95.9 %, respectively. The treated tanning wastewater showed low heavy metal levels, with removal percentages ranging from 66 %–98 % for Co, Cr, Pb, Ni, and Cd, indicating the high efficiency of γ-Fe2O3-NPs in improving treated wastewater quality.

Changes of platelet indices patients with adenomyosis during menstrual cycle

Essential trace metals play a critical role in brain development throughout fetal and postnatal life. The consequences of deficiencies for the developing brain of infants and young children can be devastating and enduring. For example, low levels of trace metals can affect behavioral and cognitive development and educability. This chapter provides an up-to-date insight into the role of the essential trace metals in brain development and function with particular focus on iron, copper, and zinc. To that end, in vitro and in vivo studies will be discussed, which illustrate the various processes that trace metals participate in on cellular, circuit, and macroscopic level within the central nervous system.

Potential use of phosphogypsum in paving blocks

The present work aims to contribute to finding more recycling routes for phosphogypsum (PG) and its potential uptake in the material construction industry as paving blocks. Laboratory testing was conducted to formulate mixes using PG as fine sand replacement. An optimal 20% substitution rate was proved. Industrially processed paving blocks were made for high-quality experimental investigation. The most interesting testing results of PG paving blocks are the low water absorption coefficient of 5.7% and excellent mechanical properties, including high compressive and flexural strengths at early age (20.7 and 4.65 MPa at 7 days, respectively). Compressive strength evolves with respect to the curing period: 26% increase at 28 days and 36% increase at 90 days; flexural strength evolves from 6% at 28 days to 10% at 90 days. The leaching test showed low levels of heavy metals released, and their concentrations were lower in the mix than in the raw PG. For all the aforementioned results, PG waste from a phosphate plant in Gabès, Tunisia was proved to have high potential for reuse in the manufacturing of paving blocks with low health risks and excellent properties. Reusing PG waste in paving blocks would thus contribute to solving an environmental issue and reduce the use of sand, which is prone to depletion as a non-renewable resource.

Recovery of ammonium and phosphate as struvite via integrated hydrolysis and incineration of sewage sludge

A sustainable struvite production pathway was proposed for the recovery of NH4+-N and PO43−-P from sewage sludge by two different pretreatments. Hydrolysis and incineration of sewage sludge yields NH4+-N rich solution (NH4+-N/PO43−-P of 2.66 in the supernatant) and phosphorus rich sewage sludge ash (SSA), respectively. From the sludge hydrolysate and the leachate of SSA, 88.0 % of NH4+-N and 94.1 % of PO43−-P were successfully recovered as struvite. Spectroscopic and chemical analyses showed that the recovered product had a composition of PO43−-P (12.5 %), NH4+-N (5.3 %), Mg2+ (9.3 %). It also had high struvite content (92.6 %), high P bioavailability (91.2 %), and a very low level of heavy metals to be used as an effective and environmentally friendly fertilizer.

Innovative substrates for sugarcane seedling production: Sewage sludges and rice husk ash in a waste-to-product strategy

Recent advances in the sucroenergy production chain include a new way of planting sugarcane based on a method of seedling propagation which requires a significant amount of substrate. Since the sucroenergy sector has been noted as having cleaner energy production, it is imperative that sustainable substrates suitable for the production of sugarcane seedlings be developed. Therefore, the main objective of this study was to develop innovative substrates with solar-dried sewage sludges and rice husk ash to compose substrates for sugarcane seedling production. Batches of sewage sludges were collected in open drying beds from three different municipal wastewater treatment plants from the Rio Grande do Sul State, Brazil: from Passo Fundo city (treated by anaerobic digestion), from Rio Grande city (aerobic digestion) and from Santa Maria city (aerobic digestion). Rice husk ash was obtained from a rice processing industry in the Pelotas industrial region in southern Brazil. The content of trace elements and the pathogenicity of pure sewage sludge (SS) were analyzed. The nutrient content of SS and rice husk ash (RHA) was determined. Twelve substrates with differing ratios of SS, RHA, and vermiculite were formulated to evaluate the subsequent development of sugarcane seedlings. Chemical and physical attributes were determined in all substrates and compared to a commercial substrate. The experiment was conducted in a greenhouse using mini-setts of sugarcane of the RB867515 genotype. Fifteen days after planting the seedlings were evaluated for stalk diameter, shoot height, shoot dry weight and root, and the Dickson quality index was determined. Sewage sludge showed low levels of heavy metals and pathogenic organisms and high contents of nutrients, especially nitrogen, phosphorus and micronutrients such as Zn and Cu, showing promising suitability as a substrate component for seedling production. In general, substrates of all tested proportions of SS and RHA promoted greater shoot and root dry weight and a superior Dickson Quality Index than the commercial substrate used as reference, except for the formulation containing 87.5 % SS. The viability of combining sludges from municipal wastewater treatment plants and rice husk ash into one product was confirmed using a set of biometric attributes and nutrient tissue contents obtained from the production of sugarcane seedlings.

Trace Metal Composition of Bulk Precipitation in Selected Locations of Kandy District, Sri Lanka

Atmospheric precipitation in Sri Lanka occurs mainly through rain whose terrestrial composition significantly varies based on the location as the regional geography and anthropogenic factors can largely affect environmental pollutants that are added to the atmosphere. It is therefore very important to have baseline data on the chemical composition of the atmosphere to take regulatory measures to control atmospheric pollution although very limited data available in Sri Lanka. The main objective of this study was thus to quantitatively determine selected trace metals (Al, Cr, Cu, Fe, Mn, Pb, and Zn) in bulk precipitation samples collected weekly in three sampling locations, namely the University of Peradeniya (UoP), Polgolla, and Kandy City Central (KCC), for a period of 1 year from March 2018 to March 2019. Trace metals determined using atomic emission spectrophotometry indicated that the KCC site showed the highest contamination following the sequence (with respective volume-weighted mean (VWM) concentration values) of Al (79.7 μg L−1) > Fe (42.8 μg L−1) > Zn (39.3 μg L−1) > Mn (13.9 μg L−1) > Cu (9.8 μg L−1) > Cr (2.4 μg L−1). The corresponding values of the Polgolla site showed the sequence Zn (64.3 μg L−1) > Al (52.1 μg L−1) > Fe (17.9 μg L−1) > Mn (11.1 μg L−1) > Cu (5.4 μg L−1) > Cr (1.8 μg L−1). Due to less industrialization and less traffic congestion, the UoP site showed low trace metal levels in the order Zn (29.8 μg L−1) > Al (21.3 μg L−1) > Fe (14.2 μg L−1) > Cu (7.4 μg L−1) > Mn (4.3 μg L−1) > Cr (0.9 μg L−1). Principal component analysis indicated that Cu, Mn, and Zn originated mainly from anthropogenic activities, such as combustion of fossil fuel and burning of municipal waste, while Al and Fe mainly originated from natural sources.

Potential of Accumulation and Application of Dominant Plants in Lanping Lead-zinc Mine, Yunnan Province

A field investigation in the abandoned lead-zinc mines in Yunan Province was conducted to assess the accumulation potential of dominant plant species and six heavy metals in mine soils. Eighteen types of plants were selected for the analysis. Local plants and soil were sampled and analyzed for cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and Zn (zinc) concentrations. Bioconcentration and translocation factors were calculated. Cluster analysis was performed to calculate the accumulation potential. The results showed that all dominant plants (18 species and 13 families) were herbaceous plants. The content of heavy metals in these plants was higher than their normal content in plants. The above-ground Cd content of Corydalis yanhusuo, Carum bretschneideri, and Picris hieracioides reached 62.29, 76.49, and 85.09 mg ·kg-1. The bioconcentration factors of Cd in these three plants were 0.57, 0.58, and 0.66, and the translocation factors were 0.89, 0.45, and 1.48, respectively. These plants have a strong ability to absorb and transfer Cd in soil; hence, they have the potential to remediate the Cd-contaminated soil. The above-ground Cd content of Euphorbia fischeriana and Cynoglossum amabile were 0.46 mg ·kg-1and 0.23 mg ·kg-1, respectively, and the bioconcentration factors were less than 0.01. These two plants accumulate low levels of heavy metals and thus, are suitable for growth in high altitude areas of Southwest China. They are considered economic plants for safe use in Cd-contaminated farmlands and have high application value. To protect the ecological environment of the mining areas, the other 13 plants having good tolerance to heavy metal pollution can be used as vegetation restoration plants in mining areas.

Low levels of salivary metals, oral microbiome composition and dental decay

Salivary microbiome composition can change following exposure to environmental toxicants, e.g., heavy metals. We hypothesized that levels of salivary nutrients and metals would correlate with salivary microbiome composition and be associated with dental decay. Here we assess the salivary concentrations of 5 essential minerals (cobalt, copper, manganese, molybdenum, and zinc), 4 metals with some evidence of normal physiological function (chromium, nickel, tungsten, and vanadium), and 12 with known toxicity (antimony, arsenic, barium, beryllium, cadmium, cesium, lead, mercury, platinum, thallium, tin, and uranium), and their associations with salivary microbiome composition and dental decay in 61 children and adults. 16 metals were detected in 54% of participants; 8 were found in all. Marked differences in salivary bacterial taxa were associated with levels of antimony, arsenic, and mercury, after adjusting for multiple testing. Further, antimony levels were associated with the presence of decayed teeth. Thus, salivary metal levels, even at low concentrations, may impact oral health.

Wastewater nutrient recovery using twin-layer microalgae technology for biofertilizer production.

This study evaluates the feasibility of advanced biofilm microalgae cultivation in a twin layer (TL) system for nutrient removal (N and P) as the tertiary treatment in small wastewater treatment plants (WWTPs) located in sensitive areas. Furthermore, the potential valorisation of microalgae biomass as a component of bio-based fertilizers is assessed. Scenedesmus sp. was chosen among 33 microalgae strains for inoculation of TL due to its high growth rate and its nutrient uptake capacity. The tests carried out in the prototype were markedly efficient for total soluble and ammoniacal nitrogen removal (up to 66 and 94%, respectively). In terms of potential valorisation of microalgae, the nutrient content was 5.5% N (over 40% protein), 8.8% P2O5 and 1.5% K2O, high enzymatic activity, very low levels of heavy metals and no detectable pathogen presence. However, in the formulation of solid-state bio-based fertilizers, the microalgae proportions in blends of over 2% of microalgae led to negative effects on ryegrass (Lolium perenne L. ssp.) and barley (Hordeum vulgare ssp.). The obtained results demonstrate that TL represents a promising technology, which allows efficient tertiary treatment of urban wastewater and the production of high-quality bio-based fertilizer.

Preparation of green biosorbent using rice hull to preconcentrate, remove and recover heavy metal and other metal elements from water

Sodium hydroxide treated rice hulls were investigated to preconcentrate, remove, and recover metal ions including Be2+, Al3+, Cr3+, Co2+, Ni2+, Cu2+, Zn2+, Sr2+, Ag+, Cd2+, Ba2+, and Pb2+ in both batch mode and column mode. Sodium hydroxide treatment significantly improved the removal efficiency for all metal ions of interest compared to the untreated rice hull. The removal kinetics were extremely fast for Co, Ni, Cu, Zn, Sr, Cd, and Ba, which made the treated rice hull a promising economic green adsorbent to preconcentrate, remove, and recover low-level metal ions in column mode at relatively high throughput. The principal removal mechanism is believed to be the electrostatic attraction between the negatively charged rice hulls and the positively charged metal ions. pH had a drastic impact on the removal for different metal ions and a pH of 5 worked best for most of the metal ions of interest. Processed rice hulls provide an economic alternative to costly resins that are currently commercially available products designed for metal ion preconcentration for trace metal analysis, and more importantly, for toxic heavy metal removal and recovery from the environment.

Characterization of residues from non-woody pulping process and its function as fertilizer

Pulping and paper industries using non-woody feedstocks face the challenge of its notorious waste disposal problem. To resolve this problem, in this study, we evaluated a variety of properties of solid residues reclaimed from the effluents of both wheat straw ammonium sulfate and Kraft pulping processes as organic fertilizers. The results show that both residues from the ammonium sulfate (RAS) and Kraft pulping (RKP) processes possess desirable C/N ratios, appropriate nutritional compositions, and low levels of harmful heavy metals. The high solubilities (>35 g/L) of both residues allow their use for fertigation or foliar applications. The salt index (30–50) is within the range of commercial chemical fertilizers such as potassium sulfate (42.6) and magnum sulfate (44). The E3/E5 ratios of residues suggest that the residues have small molecular sizes, which are similar to fulvic acids. Overall, wheat straw pulping residues demonstrate the potential as the sustainable organic fertilizers and the beneficial soil amendments. This work has the potential to resolve the severer effluent disposal problem faced by the non-woody pulping and papermaking industries, open a door to effectively utilize residues as value-added byproducts, and lead to both environmental sustainability and economic benefits.

Toenail metal concentrations and age at menopause: A prospective study.

Menopause timing is related to cancer, cardiovascular disease, and mortality. Lead has been associated with an earlier age at menopause, but no study has considered exposure to other metals or multiple metals simultaneously. At baseline, we measured toenail concentrations of 16 metals for 903 premenopausal women in the Sister Study (2003-2009). Age at menopause was ascertained through follow-up questionnaires. Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between individual metals and age at menopause. We used quantile-g-computation to examine the association between age at menopause and the joint effect of a simultaneous increase in (1) all metals and for subgroups of metals categorized as (2) essential or (3) non-essential. For individual metals, we observed negligible associations except for an interquartile range increase in lead which was modestly associated with an earlier age at menopause (HR = 1.03, 95% CI = 1.01, 1.05). In the mixture analyses, a quartile increase in all metals was associated with a later age at menopause (HR = 0.81, 95% CI = 0.64, 1.02). The metals with the largest negative contributions (i.e., associated with a later age at menopause) were chromium and nickel. The joint effect for the essential metals remained inverse (HR = 0.83, 95% CI = 0.64, 1.07), but was attenuated for nonessential metals (HR = 0.98, 95% CI = 0.76, 1.24). Although no individual metal was strongly associated with age at menopause, our joint effect analysis suggests that having low levels of essential metals could be associated with an earlier age at menopause.