Assessing the water quality in a World Heritage Site using biomarkers in top fish predators

The use of biomarkers in fish for biomonitoring is a valuable approach to reveal effects of human impacts on biota health. Top predator fish are effective models for monitoring human activities' impacts on aquatic ecosystems. The Guaraguaçu River is the largest river-system on coastal region of South Brazil and a World Heritage site. The river receives contaminants from disorderly urban growth, including discharges of domestic sewage and small fishery boats, particularly during the tourist season. Our study aimed to assess impact of anthropogenic activities on water quality in the Guaraguaçu River by analyzing environmental contamination biomarkers in the top fish predator Hoplias malabaricus. Fish were collected using a fyke net trap across sectors representing a gradient of anthropic impact: sector 1 - pristine; sector 2 - impacted; and sector 3 - less impacted. Water samples were collected to analyze the presence of trace elements and pesticide. Biomarkers of the antioxidant system, histopathology, genotoxicity, neurotoxicity, and concentration of trace elements were analyzed in fish tissues. In water samples Al, Fe and Mn were detected, but no pesticides were found. In fish muscle, zinc and iron were detected. Brain acetylcholinesterase activity decreased in impacted sectors, indicating neurotoxic effects. The antioxidant system increased activity in gills and liver, and damage from lipoperoxidation was observed, particularly in sector 2 when compared to sector 1, suggesting oxidative stress. Histopathological biomarkers revealed lesions in the liver and gills of fish in impacted sectors. Micronuclei, a genotoxicity biomarker, were observed in organisms from all sectors. Our results demonstrate detrimental effects of poor water quality on biota health, even when contaminants are not detected in water.

US drinking water quality: exposure risk profiles for seven legacy and emerging contaminants

BACKGROUND

Advances in drinking water infrastructure and treatment throughout the 20th and early 21st century dramatically improved water reliability and quality in the United States (US) and other parts of the world. However, numerous chemical contaminants from a range of anthropogenic and natural sources continue to pose chronic health concerns, even in countries with established drinking water regulations, such as the US.

OBJECTIVE/METHODS

In this review, we summarize exposure risk profiles and health effects for seven legacy and emerging drinking water contaminants or contaminant groups: arsenic, disinfection by-products, fracking-related substances, lead, nitrate, per- and polyfluorinated alkyl substances (PFAS) and uranium. We begin with an overview of US public water systems, and US and global drinking water regulation. We end with a summary of cross-cutting challenges that burden US drinking water systems: aging and deteriorated water infrastructure, vulnerabilities for children in school and childcare facilities, climate change, disparities in access to safe and reliable drinking water, uneven enforcement of drinking water standards, inadequate health assessments, large numbers of chemicals within a class, a preponderance of small water systems, and issues facing US Indigenous communities.

RESULTS

Research and data on US drinking water contamination show that exposure profiles, health risks, and water quality reliability issues vary widely across populations, geographically and by contaminant. Factors include water source, local and regional features, aging water infrastructure, industrial or commercial activities, and social determinants. Understanding the risk profiles of different drinking water contaminants is necessary for anticipating local and general problems, ascertaining the state of drinking water resources, and developing mitigation strategies.

IMPACT STATEMENT

Drinking water contamination is widespread, even in the US. Exposure risk profiles vary by contaminant. Understanding the risk profiles of different drinking water contaminants is necessary for anticipating local and general public health problems, ascertaining the state of drinking water resources, and developing mitigation strategies.

Lifetime exposure to brominated trihalomethanes in drinking water and swimming pool attendance are associated with chronic lymphocytic leukemia: a Multicase-Control Study in Spain (MCC-Spain)

BACKGROUND

Chronic lymphocytic leukemia (CLL) etiology is poorly understood, and carcinogenic chemicals in drinking and recreational water are candidates.

OBJECTIVE

To evaluate the association between drinking-water exposure to trihalomethanes (THMs) and nitrate as well as lifetime swimming pool attendance and CLL.

METHODS

During 2010-2013, hospital-based CLL cases and population-based controls were recruited in Spain, providing information on residential histories, type of water consumed and swimming pool attendance. Average THMs and nitrate levels in drinking water were linked to lifetime water consumption. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models.

RESULTS

Final samples for residential tap water analyses and swimming pool attendance analyses were 144 cases/1230 controls and 157 cases/1240 controls, respectively. Mean (SD) values for average lifetime residential brominated THMs and chloroform in tap water (μg/L), and ingested nitrate (mg/day) were 48.1 (35.6), 18.5 (6.7) and 13.7 (9.6) respectively in controls; and 72.9 (40.7), 17.9 (5.4), and 14.1 (8.8) in CLL cases. For each 10 μg/L increase of brominated THMs and chloroform lifetime-average levels, the ORs (95% CI) were 1.22 (1.14, 1.31) and 0.54 (0.34, 0.87), respectively. For each 5 mg/day increase of ingested nitrate, the OR of CLL was 0.91 (0.80, 1.04). The OR of lifetime pool users (vs. non-users) was 2.38 (1.61, 3.52). Upon performing annual frequency of attending pools analysis through categorization, the second and third categories showed an ORs of 2.36 (1.49, 3.72) and 2.40 (1.51, 3.83), respectively, and P-trend of 0.001.

IMPACT STATEMENT

This study identifies an association of long-term exposure to THMs in drinking water, at concentrations below the regulatory thresholds and WHO guidelines, and swimming pool attendance, with chronic lymphocytic leukemia (CLL). These unprecedented findings are highly relevant since CLL is an incurable cancer with still unknown etiology and because the widespread exposure to chlorination by-products that remain in drinking and recreational water worldwide. Despite the demonstrated carcinogenicity in animals of several chlorination by-products, little is known about their potential risks on human health. This study makes a significant contribution to the search for environmental factors involved in the etiology of CLL and to the evidence of the health impact of these high prevalent water contaminants.

Various species of Basidiomycota fungi reveal different abilities to degrade pharmaceuticals and also different pathways of degradation

The presence of pharmaceuticals (PhACs) in the aquatic environment is an emerging problem worldwide. PhACs reach surface water via the effluents of wastewater treatment plants (WWTPs). WWTPs, although able to remove organic pollutants, do not always remove PhACs. Currently, in the treatment of sewage with the activated sludge method, numerous microorganisms are used, mostly bacteria. Nevertheless, these microorganisms are not resistant to many drug contaminants, and some may also pose a risk to human health. White-rot fungi (WRF), which degrade a wide spectrum of environmental pollutants, may be used as an alternative to microorganisms. However, little data exists comparing the removal of various PhACs by different WRF. In this study, we aimed to determine the ability of three WRF Basidiomycota species, Armillaria mellea, Phanerochaete chrysosporium, and Pleurotus ostreatus, to remove PhACs from various therapeutic groups over the course of 1 h-4 days. Additionally, we identified the fungal metabolites of PhACs, proposed the degradation pathways, and assessed the toxicity of the post-culture media. All selected WRF removed PhACs, but the degree of removal depended on WRF species and PhACs type. Antidepressants and immunosuppressants were removed most efficiently by P. ostreatus, cardiovascular drugs and sulfamethoxazole by A. mellea, and erythromycin by P. chrysosporium. The vast differences observed highlight the need for more intensive testing of different WRF species to select the best species for removing pharmaceuticals of interest. The structure of metabolites generated during degradation strongly depended on WRF species, but the most frequent xenobiotic transformations were oxidation and dealkylation. The obtained results gave insight into the substrate specificity of selected WRF while also providing a broad extension of the knowledge of pharmaceutical degradation by A. mellea.

Effects of ball milling on biochar adsorption of contaminants in water: A meta-analysis

Reckless release of contaminants into the environment causes pollution in various aquatic systems on a global scale. Biochar is potentially an inexpensive and environmentally friendly adsorbent for removing contaminants from water. Ball milling has been used to enhance biochar's functionality; however, global analysis of the effect of ball milling on biochar's capacity to adsorb contaminants in aqueous solutions has not yet been done. Here, we conducted a meta-analysis to investigate the effects of ball milling on the adsorption/removal capacity of biochar for contaminants in aqueous solutions, and to investigate whether ball milling effects are related to biochar production, ball milling, and other experimental variables. Overall, ball milling significantly increased biochar adsorption capacity towards both inorganic and organic contaminants, by 69.9% and 561.9%, respectively. This could be attributed to ball milling increasing biochar surface area by 2.05-fold, pore volume by 2.39-fold, and decreasing biochar pH by 0.83-fold. The positive adsorption effects induced by ball milling varied widely, with the most effective being ball milling for 12 to 24 h at 300 to 400 rpm with a biochar:ball mass ratio of 1:100 on biochars produced at 400-550 °C from wood residues. Based on this meta-analysis, we conclude that ball milling could effectively enhance biochar's ability to remove organic and inorganic contaminants from aquatic systems.

A hypothetical model of multi-layered cost-effective wastewater treatment plant integrating microbial fuel cell and nanofiltration technology: A comprehensive review on wastewater treatment and sustainable remediation

Wastewater management has emerged as an uprising concern that demands immediate attention from environmentalists worldwide. Indiscriminate and irrational release of industrial and poultry wastes, sewage, pharmaceuticals, mining, pesticides, fertilizers, dyes and radioactive wastes, contribute immensely to water pollution. This has led to the aggravation of critical health concerns as evident from the uprising trends of antimicrobial resistance, and the presence of xenobiotics and pollutant traces in humans and animals due to the process of biomagnification. Therefore, the development of reliable, affordable and sustainable technologies for the supply of fresh water is the need of the hour. Conventional wastewater treatment often involves physical, chemical, and biological processes to remove solids from the effluent, including colloids, organic matter, nutrients, and soluble pollutants (metals, organics). Synthetic biology has been explored in recent years, incorporating both biological and engineering concepts to refine existing wastewater treatment technologies. In addition to outlining the benefits and drawbacks of the current technologies, this review addresses novel wastewater treatment techniques, especially those using dedicated rational design and engineering of organisms and their constituent parts. Furthermore, the review hypothesizes designing a multi-bedded wastewater treatment plant that is highly cost-efficient, sustainable and requires easy installation and handling. The novel setup envisages removing all the major wastewater pollutants, providing water fit for household, irrigation and storage purposes.

Pesticides monitoring in biological fluids: Mapping the gaps in analytical strategies

Pesticides play a key-role in the development of the agrifood sector allowing controlling pest growth and, thus, improving the production rates. Pesticides chemical stability is responsible of their persistency in environmental matrices leading to bioaccumulation in animal tissues and hazardous several effects on living organisms. The studies regarding long-term effects of pesticides exposure and their toxicity are still limited to few studies focusing on over-exposed populations, but no extensive dataset is currently available. Pesticides biomonitoring relies mainly on chromatographic techniques coupled with mass spectrometry, whose large-scale application is often limited by feasibility constraints (costs, time, etc.). On the contrary, chemical sensors allow rapid, in-situ screening. Several sensors were designed for the detection of pesticides in environmental matrices, but their application in biological fluids needs to be further explored. Aiming at contributing to the implementation of pesticides biomonitoring methods, we mapped the main gaps between screening and chromatographic methods. Our overview focuses on the recent advances (2016-2021) in analytical methods for the determination of commercial pesticides in human biological fluids and provides guidelines for their application.

A non-target screening study of high-density polyethylene pipes revealed rubber compounds as main contaminant in a drinking water distribution system

Polyethylene (PE) pipes are often the material of choice for water supply systems, thanks to their favorable properties, such as high strength-density ratio and corrosion resistance. However, previous studies have shown that organic compounds can migrate from PE pipes to the water. This study aimed to identify potential organic compounds migrating from high-density PE (HDPE) pipes used to distribute drinking water in Denmark, based on laboratory experiments and sampling in the distribution system using a two-tiered study design. In the first tier, migration of volatile and semi-volatile organic compounds (VOCs and semi-VOCs) from HDPE pipes were investigated over one, three, and nine days in laboratory experiments, performed according to modified standards for migration testing (EN 12,873-1). The analytical workflow consisted of solid-phase extraction (SPE) for 10,000 times enrichment and gas chromatography - mass spectrometry (GC-MS) analysis from the water phase after migration. A total of 133 compounds originating from the PE pipes were detected. Thirty-one compounds were detected by suspect screening (SS), while the remaining 102 compounds were detected by non-target screening (NTS) analysis. Among the detected compounds were also hindered amine stabilizers (HALS), flame retardant, and plasticizer tris(2-chloroethyl) phosphate. In the second tier, drinking water from a water distribution system in Copenhagen, Denmark, with a newly installed HDPE pipe was sampled and analyzed with GC-MS and liquid chromatography high-resolution mass spectrometry (LCHRMS). A total of 51 compounds were detected in the water, 12 of which were assigned to migration from HDPE. Surprisingly, HDPE antioxidants and their degradation products contributed only a relatively small percentage of the total measured compound intensities in the drinking water distribution system. Instead, a larger proportion of the compounds detected were assigned to rubber seals, used upstream in the water system from the abstraction site to delivery at the consumer tap. Seals are considered trifle in the larger picture of materials in contact with drinking water, however these results may cause a reconsideration of this position.

Facile nanoplastics formation from macro and microplastics in aqueous media

The immense production of plastic polymers combined with their discordancy with nature has led to vast plastic waste contamination across the geosphere, from the oceans to freshwater reservoirs, wetlands, remote snowpacks, sediments, air and multiple other environments. These environmental pollutants include microplastics (MP), typically defined as small and fragmented plastics less than 5 mm in size, and nanoplastics (NP), particles smaller than a micrometer. The formation of micro and nanoplastics in aqueous media to date has been largely attributed to fragmentation of plastics by natural (i.e., abrasion, photolysis, biotic) or industrial processes. We present a novel method to create small microplastics (≲ 5 μm) and nanoplastics in water from a wide variety of plastic materials using a small volume of a solubilizer liquid, such as n-dodecane, in combination with vigorous mixing. When the suspensions or solutions are subjected to ultrasonic mixing, the particle sizes decrease. Small micro- and nanoparticles were made from commercial, real world and waste (aged) polyethylene, polystyrene, polycarbonate and polyethylene terephthalate, in addition to other plastic materials and were analyzed using dark field microscopy, Raman spectroscopy and particle size measurements. The presented method provides a new and simple way to create specific size distributions of micro- and nanoparticles, which will enable expanded research on these plastic particles in water, especially those made from real world and aged plastics. The ease of NP and small MP formation upon initial mixing simulates real world environments, thereby providing further insight into the behavior of plastics in natural settings.

Oxidative stress, glutathione, and CYP2E1 in 1,4-dioxane liver cytotoxicity and genotoxicity: insights from animal models

1,4-Dioxane (DX) is an emerging drinking water contaminant worldwide, which poses a threat to public health due to its demonstrated liver carcinogenicity and potential for human exposure. The lack of drinking water standards for DX is attributed to undetermined mechanisms of DX carcinogenicity. This mini-review provides a brief discussion of a series of mechanistic studies, wherein unique mouse models were exposed to DX in drinking water to elucidate redox changes associated with DX cytotoxicity and genotoxicity. The overall conclusions from these studies support a direct genotoxic effect by high dose DX and imply that oxidative stress involving CYP2E1 activation may play a causal role in DX liver genotoxicity and potentially carcinogenicity. The mechanistic data derived from these studies can serve as important references to refine the assessment of carcinogenic pathways that may be triggered at environmentally relevant low doses of DX in future animal and human studies.

Model development for evidence-based prioritisation of policy action on emerging chemical and microbial drinking water risks

While the burden of disease from well-studied drinking water contaminants is declining, risks from emerging chemical and microbial contaminants arise because of social, technological, demographic and climatological developments. At present, emerging chemical and microbial drinking water contaminants are not assessed in a systematic way, but reactively and incidence based. Furthermore, they are assessed separately despite similar pollution sources. As a result, risks might be addressed ineffectively. Integrated risk assessment approaches are thus needed that elucidate the uncertainties in the risk evaluation of emerging drinking water contaminants, while considering risk assessors' values. This study therefore aimed to (1) construct an assessment hierarchy for the integrated evaluation of the potential risks from emerging chemical and microbial contaminants in drinking water and (2) develop a decision support tool, based on the agreed assessment hierarchy, to quantify (uncertain) risk scores. A multi-actor approach was used to construct the assessment hierarchy, involving chemical and microbial risk assessors, drinking water experts and members of responsible authorities. The concept of value-focused thinking was applied to guide the problem-structuring and model-building process. The development of the decision support tool was done using Decisi-o-rama, an open-source Python library. With the developed decision support tool (uncertain) risk scores can be calculated for emerging chemical and microbial drinking water contaminants, which can be used for the evidence-based prioritisation of actions on emerging chemical and microbial drinking water risks. The decision support tool improves existing prioritisation approaches as it combines uncertain indicator levels with a multi-stakeholder approach and integrated the risk assessment of chemical and microbial contaminants. By applying the concept of value-focused thinking, this study addressed difficulties in evidence-based decision-making related to emerging drinking water contaminants. Suggestions to improve the model were made to guide future research in assisting policy makers to effectively protect public health from emerging drinking water risks.

Spectroscopic analysis of microplastic contaminants in an urban wastewater treatment plant from Seoul, South Korea

In this study, a systematic multi-spectroscopic analysis of microplastics (MPs) sampled from a metropolitan area of Seoul was undertaken to elevate understanding of the role of wastewater treatment plants (WWTPs) in eliminating suspended contaminants including MPs before releasing the effluent water into the environment. We analyzed pollutants in influent and effluent samples from a WWTP in Seoul, South Korea. Spectroscopic and microscopic methods were used to analyze MPs. Fourier-transform infrared (FT-IR) spectroscopy in the wavenumber region between 4000 and 715 cm^-1 was employed to estimate the abundance of MPs in wastewater. Stereomicroscope images and Nile red staining were used to facilely identify MPs in both influents and effluents to compare the results with those of FT-IR data. Hyperspectral imaging could identify MPs in the influent sample with the reflection method at 400-900 nm. Our preliminary results indicate that the most observed MPs after the wastewater were filtered by a 45 μm stainless steel mesh filter were polyethylene (PE) and polypropylene (PP). The total number of the prevalent MPs in influent samples decreased significantly. Nanostructure particles could be found by field-emission scanning electron microscopy (FE-SEM). Our combined multi-spectroscopic study should be helpful to provide a guideline for the rapid spectroscopic analysis of freshwater in the Han River, Seoul, South Korea.

A critical review on recent developments in MOF adsorbents for the elimination of toxic heavy metals from aqueous solutions

Effective and substantial remediation of contaminants especially heavy metals from water is still a big challenge in terms of both environmental and biological perspectives because of their adverse effects on the human health. Many techniques including adsorption, ion exchange, co-precipitation, chemical reduction, ultrafiltration, etc. are reported for eliminating heavy metal ions from the water. However, adsorption has preferred because of its simple and easy handlings. Several types of adsorbents are observed and documented well for the purpose. Recently, highly porous metal-organic frameworks (MOFs) were developed by incorporating metals and organic ligands together and claimed as potent adsorbents for the remediation of highly toxic heavy metals from the aqueous solutions due to their unique features like greater surface area, high chemical stability, green and reuse material, etc. In this review, the authors discussed systematically some recent developments about secure MOFs to eliminate the toxic metals such as arsenic (both arsenite and arsenate), chromium(VI), cadmium (Cd), mercury (Hg) and lead (Pb). MOFs are observed as the most efficient adsorbents with greater selectivity as well as high adsorption capacity for metallic contamination. Graphical abstract.

Comprehensive evaluation of substrate materials for contaminants removal in constructed wetlands

Considerable number of studies have been carried out to develop and apply various substrate materials for constructed wetlands (CWs), however, there is a lack of method and model for comprehensive evaluation of different types of CWs substrates. To this end, this article summarized nearly all the substrate materials of CWs available in the literatures, including natural materials, agricultural/industrial wastes and artificial materials. The sources and physicochemical properties of various substrate materials, as well as their removal capacities for main water contaminants including nutrients, heavy metals, surfactants, pesticides/herbicides, emerging contaminants and fecal indicator bacteria (FIB) were comprehensively described. Further, a scoring model for the substrate evaluation was constructed based on likely cost, availability, permeability, reuse and contaminant removal capacities, which can be used to select the most suitable substrate material for different considerations. The provided information and constructed model contribute to better understanding of CWs substrate for readers, and help solve practical problems on substrates selection and CWs construction.

Cumulative risk analysis of carcinogenic contaminants in United States drinking water

Cumulative risk analysis of contaminant occurrence in United States drinking water for the period of 2010-2017 indicates that over 100,000 lifetime cancer cases could be due to carcinogenic chemicals in tap water. The majority of this risk is due to the presence of arsenic, disinfection byproducts and radioactive contaminants. For different states within the U.S., cumulative cancer risk for drinking water contaminants ranges between 1 × 10^-4 and 1 × 10^-3, similar to the range of cumulative cancer risks reported for air pollutants. Overall, national attributable risk due to tap water contaminants is approximately 4 × 10^-4, which is two orders of magnitude higher than the de minimus cancer risk of one-in-a-million. Thus, decreasing the levels of chemical contaminants in drinking water represents an important opportunity for protecting public health.

Extraction and quantitative analysis of water by GC/MS for trace-level dimethylsilanediol (DMSD)

Dimethylsilanediol (DMSD) is related to the most important bifunctional building block for silicone oligomers and polymers, although DMSD itself is not used in any commercial applications. The environmental release of DMSD is linked to the hydrolytic degradation of other silicone materials in soil and water as DMSD is usually one of the major products. Most common extraction and quantification methods are not suitable for the analysis of trace- and ultratrace-levels of DMSD in water. This is because DMSD is highly water soluble and can readily undergo self-condensation when concentrated. In addition, DMSD may also coexist with DMSD precusors such methylsiloxanes in water. In the present study, solid-phase extraction (SPE) in combination with gas chromatography-mass spectrometry (GC/MS) without pre-column derivatization was tested for analyzing water samples for DMSD. It was found that direct analysis by GC/MS can be used for a wide range of concentrations if DMSD was extracted into a dry organic solvent. Isolute^® ENV + may be used for such extraction at higher DMSD concentrations, while Supelclean™ ENVI-Carb™ Plus was found to be better for trace and ultratrace analysis. Increased salt content in water can increase its DMSD extraction efficiency, while polarity of the eluting solvents is a determining factor for eluting efficiency. Moisture in the final extract is a detrimental factor for direct GC/MS analysis. With a proper moisture removal procedure and a suitable internal standard, coupling of SPE and direct GC/MS analysis reduces the method detection limits for DMSD to lower ppb levels. Based on field sample analysis, solvent and instrumental background, not instrumental sensitivity, was found to be the limiting factor in lowering the detection limits for this analysis.

Duckweed biomarkers for identifying toxic water contaminants?

Surface or ground waters can be contaminated with numerous toxic substances. The duckweeds Lemna minor and Lemna gibba are widely used for assaying waterborne toxicity to higher plants in terms of growth inhibition and photosynthetic pigment reduction. These tests cannot, however, in themselves determine the nature of the agents responsible for toxicity. Morphological, developmental, physiological, biochemical, and genetic responses of duckweeds to exposure to toxic water contaminants constitute biomarkers of toxic effect. In principle, the very detection of these biomarkers should enable the contaminants having elicited them (and being responsible for the toxicity) to be identified. However, in practice, this is severely compromised by insufficient specificity of biomarkers for their corresponding toxicants and by the lack of documentation of biomarker/toxin relationships. The present contribution illustrates the difficulties of using known water contaminant-related duckweed biomarkers to identify toxins, and discusses possibilities for achieving this goal.

Braid solid-phase microextraction of polycyclic aromatic hydrocarbons by using fibers coated with silver-based nanomaterials in combination with HPLC with fluorometric detection

Authors propose a novel braid support configuration for use in solid-phase microextraction (SPME) fibers. Two different braided supports (double and triple) were prepared and compared with the conventional single support configuration. Three kinds of silver-based nanomaterials that serve as coatings on these supports are described. They included silver dendrites, silver nanoparticles (AgNPs), and silver dendrites decorated with AgNPs (Ag-dendrites@AgNPs). They were prepared by electrodeposition, a layer-by-layer (LBL) method, and a hybrid strategy, respectively. Fibers were used in the direct-immersion (DI) mode of SPME. Five polycyclic aromatic hydrocarbons (PAHs) were studied as model analytes by DI-SPME when analyzing (spiked) underground waters. PAHs were further determined with high-performance liquid chromatography (HPLC) and fluorescence detection. The analytical performance of the fibers was compared to that of the commercial polydimethylsiloxane (PDMS) fiber of 100 μm thickness. AgNPs obtained by LBL was the best coating and the double braid was the best support configuration. The configuration of the SPME support always played an important role independently on the coating material, being always beneficial the use of double-braids. Despite the low coatings volumes of the silver-based fibers compared to that of PDMS, the analytical features of the method were adequate. Figures of merit include: (a) limits of detection down to 20 ng·L^-1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) of <13%, <12%, and < 13%, respectively; and (c) adequate operational lifetime (>60 extractions). Graphical abstract Schematic presentation of braided solid-phase microextraction support configurations together with different silver-based nanomaterials as coatings.

Metal-organic frameworks/carbon-based materials for environmental remediation: A state-of-the-art mini-review

In recent years, many research groups started to study the combination of metal-organic frameworks (MOFs) with nanocarbon materials, which showed the excellent improved performances than MOFs alone. The addition of carbon materials such as graphene oxides (GOs) and carbon nanotubes (CNTs) into MOFs can improve the physico-chemical properties of parent MOFs with excellent chemical robustness, high mechanical and distinguished electronic thermal robustness. These advantages facilitate the wider applications of MOFs/carbon materials (MOFs-C) in more research fields. This paper is devoted to reviewing the recent studies about the preparation and applications of MOFs-C in environmental remediation. This paper discusses the efficient adsorptive removal of a wide range of pollutants by MOFs-C, including organic contaminants and heavy metals from water as well as VOCs and some other toxic gases from atmospheric environment. Additionally, the catalytic performance of these nanocomposites for photocatalysis and Fenton-like oxidation of water pollutants is discussed in details. Meanwhile, the significant roles of nanocarbons and in-depth mechanisms for improved adsorption or catalysis are summarized. Finally, future perspectives on the development and application of MOFs-C composites for pollution remediation are presented at the end of this paper.

A community-based evaluation of proximity to unconventional oil and gas wells, drinking water contaminants, and health symptoms in Ohio

Over 4 million Americans live within 1.6 km of an unconventional oil and gas (UO&G) well, potentially placing them in the path of toxic releases. We evaluated relationships between residential proximity to UO&G wells and (1) water contamination and (2) health symptoms in an exploratory study. We analyzed drinking water samples from 66 Ohio households for 13 UO&G-related volatile organic compounds (VOCs) (e.g., benzene, disinfection byproducts [DBPs]), gasoline-range organics (GRO), and diesel-range organics. We interviewed participants about health symptoms and calculated metrics capturing proximity to UO&G wells. Based on multivariable logistic regression, odds of detection of bromoform and dibromochloromethane in surface water decreased significantly as distance to nearest UO&G well increased (odds ratios [OR]: 0.28-0.29 per km). Similarly, distance to nearest well was significantly negatively correlated with concentrations of GRO and toluene in ground water (r_Spearman: -0.40 to -0.44) and with concentrations of bromoform and dibromochloromethane in surface water (r_Spearman: -0.48 to -0.50). In our study population, those with higher inverse-distance-squared-weighted UO&G well counts within 5 km around the home were more likely to report experiencing general health symptoms (e.g. stress, fatigue) (OR: 1.52, 95%CI: 1.02-2.26). This exploratory study, though limited by small sample size and self-reported health symptoms, suggests that those in closer proximity to multiple UO&G wells may be more likely to experience environmental health impacts. Further, presence of brominated DBPs (linked to UO&G wastewater) raises the question of whether UO&G activities are impacting drinking water sources in the region. The findings from this study support expanded studies to advance knowledge of the potential for water quality and human health impacts; such studies could include a greater number of sampling sites, more detailed chemical analyses to examine source attribution, and objective health assessments.

Gonadal intersex in smallmouth bass Micropterus dolomieu from northern Indiana with correlations to molecular biomarkers and anthropogenic chemicals

Over the past decade, studies have shown that exposure to endocrine disrupting chemicals (EDCs) can cause gonadal intersex in fish. Smallmouth bass (Micropterus dolomieu) males appear to be highly susceptible to developing testicular oocytes (TO), the most prevalent form of gonadal intersex, as observed in various areas across the U.S. In this study, prevalence and severity of TO was quantified for smallmouth bass sampled from the St. Joseph River in northern Indiana, intersex biomarkers were developed, and association between TO prevalence and organic contaminants were explored. At some sites, TO prevalence reached maximum levels before decreasing significantly after the spawning season. We examined the relationship between TO presence and expression of gonadal and liver genes involved in sex differentiation and reproductive functions (esr1, esr2, foxl2, fshr, star, lhr and vtg). We found that vitellogenin (vtg) transcript levels were significantly higher in the liver of males with TO, but only when sampled during the spawning season. Further, we identified a positive correlation between plasma VTG levels and vtg transcript levels, suggesting its use as a non-destructive biomarker of TO in this species. Finally, we evaluated 43 contaminants in surface water at representative sites using passive sampling to look for contaminants with possible links to the observed TO prevalence. No quantifiable levels of estrogens or other commonly agreed upon EDCs such as the bisphenols were observed in our contaminant assessment; however, we did find high levels of herbicides as well as consistent quantifiable levels of PFOS, PFOA, and triclosan in the watershed where high TO prevalence was exhibited. Our findings suggest that the observed TO prevalence may be the result of exposures to mixtures of nonsteroidal EDCs.

Development of a macroporous ceramic passive sampler for the monitoring of cytostatic drugs in water

The aim of this study was to develop and calibrate a macroporous ceramic passive sampler (MCPS) for the monitoring of anticancer drugs in wastewater. This system was designed by the Spanish Research Council (CSIC) and consists in a porous ceramic tube to allow a high diffusion of contaminants. The MCPS has been calibrated for 16 cytostatic drugs over time periods up to 9 d in spiked water under controlled laboratory conditions. Optimal uptake was accomplished for 7 compounds, namely ifosfamide, cyclophosphamide, capecitabine, prednisone, megestrol, cyproterone and mycophenolic acid, whereas cytarabine was not adsorbed in the receiving phase and the rest were hydrolyzed over the deployment period. The sampling rate for these 7 compounds was between 0.825 and 3.350 mL day^-1 and the diffusion coefficients varied from 1.01E-07 to 4.12E-07 cm² s^-1. To prove the applicability of the MCPSs, samplers (n = 3) were deployed in influent and effluent waters of a WWTP for a period of 6 d and results were compared to grab sampling and extraction with Solid Phase Extraction (SPE). In influent waters, MCPS were clogged due to the high amount of suspended solids in these waters. In effluents, MCPS detected cyclophosphamide and mycophenolic acid at concentrations of 19 ± 3 and 136 ± 28 ng L^-1 with a good agreement with the levels obtained by grab sampling. The study discusses the use and performance of the MCPS for the monitoring of stable cytostatic compounds in a complex matrix such as wastewater.

QSPR prediction of the hydroxyl radical rate constant of water contaminants

In advanced oxidation processes (AOPs), the aqueous hydroxyl radical (HO) acts as a strong oxidant to react with organic contaminants. The hydroxyl radical rate constant (kHO) is important for evaluating and modelling of the AOPs. In this study, quantitative structure-property relationship (QSPR) method is applied to model the hydroxyl radical rate constant for a diverse dataset of 457 water contaminants from 27 various chemical classes. The constricted binary particle swarm optimization and multiple-linear regression (BPSO-MLR) are used to obtain the best model with eight theoretical descriptors. An optimized feed forward neural network (FFNN) is developed to investigate the complex performance of the selected molecular parameters with kHO. Although the FFNN prediction results are more accurate than those obtained using BPSO-MLR, the application of the latter is much more convenient. Various internal and external validation techniques indicate that the obtained models could predict the logarithmic hydroxyl radical rate constants of a large number of water contaminants with less than 4% absolute relative error. Finally, the above-mentioned proposed models are compared to those reported earlier and the structural factors contributing to the AOP degradation efficiency are discussed.

Nitrate in drinking water and bladder cancer risk in Spain

BACKGROUND

Nitrate is a widespread contaminant in drinking water and ingested nitrate under conditions resulting in endogenous nitrosation is suspected to be carcinogenic. However, the suggested association between nitrate in drinking water and bladder cancer remains inconsistent. We evaluated the long-term exposure to drinking water nitrate as a risk factor for bladder cancer, considering endogenous nitrosation modifiers and other covariables.

METHODS

We conducted a hospital-based case-control study of bladder cancer in Spain (1998-2001). Residential histories and water consumption information were ascertained through personal interviews. Historical nitrate levels (1940-2000) were estimated in study municipalities based on monitoring records and water source. Residential histories of study subjects were linked with nitrate estimates by year and municipality to calculate individual exposure from age 18 to recruitment. We calculated odds ratios (OR) and 95% confidence intervals (CI) for bladder cancer among 531 cases and 556 controls with reliable interviews and nitrate exposure information covering at least 70% of years from age 18 to interview.

RESULTS

Average residential levels ranged from 2.1mg/L to 12.0mg/L among regions. Adjusted OR (95%CI) for average residential levels relative to ≤ 5 mg/L were 1.2 (0.7-2.0) for >5-10mg/L and 1.1 (0.6-1.9) for >10mg/L. The OR for subjects with longest exposure duration (>20 years) to highest levels (>9.5mg/L) was 1.4 (0.9-2.3). Stratification by intake of vitamin C, vitamin E, meat, and gastric ulcer diagnosis did not modify these results. A non-significant negative association was found with waterborne ingested nitrate with an OR of 0.7 (0.4-1.0) for >8 vs. ≤ 4 mg/day. Adjustment for several covariables showed similar results to crude analyses.

CONCLUSION

Bladder cancer risk was inconsistently associated with chronic exposure to drinking water nitrate at levels below the current regulatory limit. Elevated risk is suggested only among subjects with longest exposure duration to the highest levels. No evidence of interaction with endogenous nitrosation modifiers was observed.