Geographical distribution of nitrate pollution and its risk assessment using GIS and Monte Carlo simulation in drinking water in urban areas of Fars province-Iran during 2017-2021.

Pollution of water resources with nitrate is currently one of the major challenges at the global level. In order to make macro-policy decisions in water safety plans, it is necessary to carry out nitrate risk assessment in underground water, which has not been done in Fars province for all urban areas. In the current study, 9494 drinking water samples were collected in four seasons in 32 urban areas of Fars province in Iran, between 2017 and 2021 to investigate the non-carcinogenic health risk assessment. Geographical distribution maps of hazard quotient were drawn using geographical information system software. The results showed that the maximum amount of nitrate in water samples in 4% of the samples in 2021, 2.5% of the samples in 2020 and 3% of the samples in 2019 were more than the standard declared by World Health Organization guidelines (50 mg/L). In these cases, the maximum amount of nitrate was reported between 82 and 123 mg/L. The HQ values for infants did not exceed 1 in any year, but for children (44% ± 10.8), teenagers (10.8% ± 8.4), and adults (3.2% ± 1.7) exceeded 1 in cities, years, and seasons, indicating that three age groups in the studied area are at noticeably significant non-carcinogenic risk. The results of the Monte Carlo simulation showed that the average value of non-carcinogenic risk was less than 1 for all age groups. Moreover, the maximum HQ values (95%) were higher than 1 for both children and teenager, indicating a significant non-carcinogenic risk for the two age groups.

Hazard-mapping and health risk analysis of iron and arsenic contamination in the groundwater of Sylhet district.

This study investigates groundwater contamination by arsenic and iron and its health implications within the Sylhet district in Bangladesh. Utilizing geographic information system (GIS) and inverse distance weighting (IDW) methods, hazard maps have been developed to evaluate contamination risk across various upazilas. The findings show significant arsenic and iron pollution, particularly in the northwestern part of the district. In about 50% of the area, especially in Jaintiapur, Zakiganj, Companiganj, and Kanaighat where arsenic levels surpass 0.05 mg/L which is the standard limit of Bangladesh. Iron levels peak at 13.83 mg/L, severely impacting 45% of the region, especially in Gowainghat, northeastern Jaintiapur, Zakigonj, and Golabganj. The study employs USEPA health risk assessment methods to calculate the hazard quotient (HQ) and hazard index (HI) for both elements via oral and dermal exposure. Results indicate that children face greater noncarcinogenic and carcinogenic risks than adults, with oral HI showing significant risk in Balagonj and Bishwanath. Dermal adsorption pathways exhibit comparatively lower risks. Cancer risk assessments demonstrate high carcinogenic risks from oral arsenic intake in all areas. This comprehensive analysis highlights the urgent need for effective groundwater management and policy interventions in the Sylhet district to mitigate these health risks and ensure safe drinking water.

Innovative DIY drinking water disinfection for underserved communities.

Waterborne pathogens threaten 2.2 billion people lacking access to safely managed drinking water services, causing over a million annual diarrheal deaths. Individuals without access to chlorine reagents or filtration devices often resort to do-it-yourself (DIY) methods, such as boiling or solar disinfection (SODIS). However, these methods are not simple to implement. In this study, we introduced an innovative and easily implemented disinfection approach. We discovered that immersing aluminum foil in various alkaline solutions produces alkali-treated aluminum foil (ATA foil) that effectively adsorbs Escherichia coli (E. coli), Salmonella, and Acinetobacter through the generated surface aluminum hydroxide. For example, a 25 cm2 ATA foil efficiently captures all 104E. coli DH5α strains in 100 mL water within 30 min. Using a saturated suspension of magnesium hydroxide, a type of fertilizer, as the alkaline solution, the properties of the saturated suspension eliminate the need for measuring reagents or changing solutions, making it easy for anyone to create ATA foil. ATA foils can be conveniently produced within mesh bags and placed in household water containers, reducing the risk of recontamination. Replacing the ATA foil with a foil improves the adsorption efficiency, and re-immersing the used foil in the production suspension restores its adsorption capacity. Consequently, ATA foil is an accessible and user-friendly alternative DIY method for underserved communities. Verification experiments covering variations in the water quality and climate are crucial for validating the efficacy of the foil. Fortunately, the ATA foil, with DIY characteristics similar to those of boiling and SODIS, is well-suited for testing under diverse global conditions, offering a promising solution for addressing waterborne pathogens worldwide.

Evaluation of potentially toxic elements and microplastics in the water treatment facility.

The potentially harmful effects of consuming potentially toxic elements (PTEs) and microplastics (MPs) regularly via drinking water are a significant cause for worry. This study investigated PTEs (Cd, Cu, Cr, Ni, Pd, Zn, Co), MPs, turbidity, pH, conductivity, and health risk assessment in the water treatment plant in Kielce, Poland. Zn had the highest concentrations throughout the water treatment facility, whereas Cd, Pb, and Co had lower concentrations (< 0.1 µg/L). The order of the concentrations among the specified PTEs was like Zn˃Cu˃Ni˃Cr˃Cd˃Pb and Co. The minimum turbidity was 0.34, and the maximum was 1.9 NTU. The range of pH in water samples was 6.51-7.47. The conductivity was 1,203-1,445 ms in water samples. These identified MPs were categorized into fiber and fragments. The color of these identified MPs was blue, red, black, green, and transparent. The minimum and maximum size of the MPs was 196 and 4,018 µm, while the average size was 2,751 ± 1,905 µm. The average concentration of MPs per liter of the water treatment plant was 108.88 ± 55.61. The elements listed are C, O, Na, Mg, Al, Si, K, Ca, and Ti. Fe and Zn were the predominant elements seen using EDX. HQ values of the PTEs were less than one for adults and children. The human health risk associated with all detected PTEs revealed that the HQ values exhibit a satisfactory degree of non-carcinogenic adverse health risk. HI values for adults and children age groups were less than one. In most water treatment samples, the carcinogenic value exceeds the threshold value of 10-6. The PTEs and MP concentrations in drinking water should be periodically monitored to minimize consumers' environmental pollution and health risks.

Cytotoxicity of emerging halophenylacetamide disinfection byproducts in drinking water: Mechanism and prediction.

Halophenylacetamides (HPAcAms) have been identified as a new group of nitrogenous aromatic disinfection byproducts (DBPs) in drinking water, but the toxicity mechanisms associated with HPAcAms remain almost completely unknown. In this work, the cytotoxicity of HPAcAms in human hepatoma (HepG2) cells was evaluated, intracellular oxidative stress/damage levels were analyzed, their binding interactions with antioxidative enzyme were explored, and a quantitative structure-activity relationship (QSAR) model was established. Results indicated that the EC50 values of HPAcAms ranged from 2353 µM to 9780 µM, and the isomeric structure as well as the type and number of halogen substitutions could obviously induce the change in the cytotoxicity of HPAcAms. Upon exposure to 2-(3,4-dichlorophenyl)acetamide (3,4-DCPAcAm), various important biomarkers linked to oxidative stress and damage, such as reactive oxygen species, 8­hydroxy-2-deoxyguanosine, and cell apoptosis, exhibited a significant increase in a dose-dependent manner. Moreover, 3,4-DCPAcAm could directly bind with Cu/Zn-superoxide dismutase and induce the alterations in the structure and activity, and the formation of complexes was predominantly influenced by the van der Waals force and hydrogen bonding. The QSAR model supported that the nucleophilic reactivity as well as the molecular compactness might be highly important in their cytotoxicity mechanisms in HepG2 cells, and 2-(2,4-dibromophenyl)acetamide and 2-(3,4-dibromophenyl)acetamide deserved particular attention in future studies due to the relatively higher predicted cytotoxicity. This study provided the first comprehensive investigation on the cytotoxicity mechanisms of HPAcAm DBPs.

Detection and characterisation of microplastics in tap water from Gauteng, South Africa.

This study reports the presence, concentration, and characteristics of microplastics (MPs) in tap water in three suburbs in Gauteng Province in South Africa. Physical characterisation was conducted using stereomicroscopy and scanning electron microscopy following staining of MPs with the Rose Bengal dye. The concentrations of MPs in all samples ranged from 4.7 to 31 particles/L, with a mean of 14 ± 5.6 particles/L. Small-sized (<1 mm) and fibrous-shaped MPs were most abundant in all samples. Fibers accounted for 83.1% of MPs in samples from all the three areas, followed by fragments (12.4%), pellets/beads (3.1%), and films (1.5%), with a minor variation in the distribution of shapes and sizes in samples from each area. Raman microspectroscopy was used for chemical analysis, and five polymers were identified, namely: high-density polyethylene, polyurethane, polyethylene terephthalate, poly(hexamethylene terephtalamide), and poly(acrylamide-co-acrylic acid). C.I Pigment Red 1, C.I. Solvent Yellow 4, Potassium indigotetrasulphonate, and C.I Pigment Black 7 were the colourants detected. These colourants are carcinogenic and mutagenic and are potentially toxic to humans. The prevalence of MPs in tap water implies their inadequate removal during water treatment. For instance, the presence of poly(AM-co-AA) suggests that drinking water treatment plants may be a potential source of MPs in tap water. Other polymers, e.g., high-density polyethylene may be released from pipes during the transportation of drinking water. The estimated daily consumption of MPs from tap water was 1.2, 0.71, and 0.50 particles/kg.day for children, men, and women, respectively. The findings of this study provide evidence of the presence of MPs in drinking water in South Africa, thus giving some insights into the performance of treatment plants in removing these contaminants and a benchmark for the formulation of standard limits for the amount of MPs in drinking water.

Molecular-weight dependent promotion and competition effects of natural organic matter on dissolved black carbon removal by coagulation.

Dissolved black carbon (DBC) is the ubiquitous component of dissolved organic matter pools with the high reactivity for disinfection byproducts formation. However, it is unknown that the influence of molecular weight (MW) of natural organic matter (NOM) on the DBC removal from potable water sources. Therefore, it was studied that the DBC removal by coagulation in the presence of the NOM with various molecular weights. The DBC removal was promoted due to the presence of NOM and the promotion degree decreased with decreasing MW of NOM. Furthermore, the removal ratio of humic-like component increased as the MW of NOM decreased, suggesting that the competition between DBC and NOM increased with decreasing MW. The functional groups after coagulation were the same with that before coagulation as the MW of NOM varied, suggesting that the molecular structure was not the key factor of influencing the DBC removal. This study will give the deep insight into the prediction of the DBC removal ratio by coagulation based on the MW of NOM in water sources.

Effect of an Arsenic Mitigation Program on Arsenic Exposure in American Indian Communities: A Cluster Randomized Controlled Trial of the Community-Led Strong Heart Water Study Program.

BACKGROUND: Chronic arsenic exposure has been associated with an increased risk of cardiovascular disease; diabetes; cancers of the lung, pancreas and prostate; and all-cause mortality in American Indian communities in the Strong Heart Study. OBJECTIVE: The Strong Heart Water Study (SHWS) designed and evaluated a multilevel, community-led arsenic mitigation program to reduce arsenic exposure among private well users in partnership with Northern Great Plains American Indian Nations. METHODS: A cluster randomized controlled trial (cRCT) was conducted to evaluate the effectiveness of the SHWS arsenic mitigation program over a 2-y period on a) urinary arsenic, and b) reported use of arsenic-safe water for drinking and cooking. The cRCT compared the installation of a point-of-use arsenic filter and a mobile Health (mHealth) program (3 phone calls; SHWS mHealth and Filter arm) to a more intensive program, which included this same program plus three home visits (3 phone calls and 3 home visits; SHWS Intensive arm). RESULTS: A 47% reduction in urinary arsenic [geometric mean (GM)=13.2 to 7.0µg/g creatinine] was observed from baseline to the final follow-up when both study arms were combined. By treatment arm, the reduction in urinary arsenic from baseline to the final follow-up visit was 55% in the mHealth and Filter arm (GM=14.6 to 6.55µg/g creatinine) and 30% in the Intensive arm (GM=11.2 to 7.82µg/g creatinine). There was no significant difference in urinary arsenic levels by treatment arm at the final follow-up visit comparing the Intensive vs. mHealth and Filter arms: GM ratio of 1.21 (95% confidence interval: 0.77, 1.90). In both arms combined, exclusive use of arsenic-safe water from baseline to the final follow-up visit significantly increased for water used for cooking (17% to 53%) and drinking (12% to 46%). DISCUSSION: Delivery of the interventions for the community-led SHWS arsenic mitigation program, including the installation of a point-of-use arsenic filter and a mHealth program on the use of arsenic-safe water (calls only, no home visits), resulted in a significant reduction in urinary arsenic and increases in reported use of arsenic-safe water for drinking and cooking during the 2-y study period. These results demonstrate that the installation of an arsenic filter and phone calls from a mHealth program presents a promising approach to reduce water arsenic exposure among private well users. https://doi.org/10.1289/EHP12548.

Determinants of PFOA Serum Half-Life after End of Exposure: A Longitudinal Study on Highly Exposed Subjects in the Veneto Region.

BACKGROUND: Perfluoroalkyl substances (PFAS) are widely used, ubiquitous, and highly persistent man-made chemicals. Groundwater of a vast area of the Veneto Region (northeastern Italy) was found to be contaminated by PFAS from a manufacturing plant active since the late 1960s. As a result, residents were overexposed to PFAS through drinking water until 2013, mainly to perfluorooctanoic acid (PFOA). OBJECTIVES: The aim of the present study was to estimate the rates of decline in serum PFOA and their corresponding serum half-lives, while characterizing their determinants. METHODS: We investigated 5,860 subjects more than 14 years of age who enrolled in the second surveillance round of the regional health surveillance program. Two blood samples were collected between 2017 and 2022 (average time between measurements: 4 years). Serum PFOA excretion rates and half-lives were estimated based on linear mixed effect models, modeling subject-specific serum PFOA concentrations over time and correcting for background concentrations. For modeling determinants of half-life [age, sex, body mass index (BMI), smoking-habit, alcohol consumption, and estimated glomerular filtration rate (eGFR)], we added interaction terms between each covariate and the elapsed time between measurements. Perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonic acid (PFHxS) apparent half-lives were also estimated. A separate analysis was conducted in children (n=480). All analyses were stratified by sex. RESULTS: Median initial serum concentrations of PFOA was 49 ng/mL (range: 0.5-1,090), with a median reduction of 62.45%. The mean estimated PFOA half-life was 2.36 years [95% confidence interval (CI): 2.33, 2.40], shorter in women (2.04; 95% CI: 2.00, 2.08) compared to men (2.83; 95% CI: 2.78, 2.89). Half-lives varied when stratified by some contributing factors, with faster excretion rates in nonsmokers and nonalcohol drinkers (especially in males). CONCLUSIONS: This study, to our knowledge the largest on PFOA half-life, provides precise estimates in young adults whose exposure via drinking water has largely ceased. For other PFAS, longer half-lives than reported in other studies can be explained by some ongoing exposure to PFAS via other routes. https://doi.org/10.1289/EHP13152.

Dichloroacetic acid and trichloroacetic acid as disinfection by-products in drinking water are endocrine-disrupting chemicals.

Dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) are two typical non-volatile disinfection by-products (DBPs) found in drinking water. Increasing evidence has demonstrated that they show reproductive toxicity. However, whether they might have endocrine disrupting properties remains largely unknown. To discover this, we treated male mice or pregnant mice with 0, 1-, 102-, 103-, 104-, or 5 × 104-fold maximal concentration level (MCL) of DCAA or TCAA in drinking water. In male mice, the levels of testosterone in serum and androgen receptor (AR) in testis were declined with ≥ 103-fold MCL of DCAA (26.4 mg/kg/d) or TCAA (52.7 mg/kg/d). In pregnant mice, miscarriage rates were increased with ≥ 104-fold MCL of DCAA (264 mg/kg/d) or ≥ 103-fold MCL of TCAA. The levels of FSH in serum were increased and those of estradiol and progesterone were reduced with ≥ 103-fold MCL of DCAA or TCAA. The protein levels of estrogen receptors (ERα and ERß) in ovary were reduced with ≥ 102-fold MCL of DCAA (2.64 mg/kg/d) or TCAA (5.27 mg/kg/d). Exposure to some certain fold MCL of DCAA or TCAA also altered the protein levels of ERα and ERß in uterus and placenta. Exposure to 5 × 104-fold MCL of both DCAA and TCAA showed the combined effects. Therefore, both DCAA and TCAA could be considered as novel reproductive endocrine disrupting chemicals, which might be helpful for further assessment of the toxicological effects of DCAA and TCAA and the awareness of reproductive endocrine disrupting properties caused by DCAA and TCAA in drinking water.

Effects of disinfectant type and dosage on biofilm's activity, viability, microbiome and antibiotic resistome in bench-scale drinking water distribution systems.

Drinking water distribution systems (DWDSs) are important for supplying high-quality water to consumers and disinfectant is widely used to control microbial regrowth in DWDSs. However, the disinfectant's influences on microbial community and antibiotic resistome in DWDS biofilms and the underlying mechanisms driving their dynamics remain elusive. The study investigated the effects of chlorine and chloramine disinfection on the microbiome and antibiotic resistome of biofilms in bench-scale DWDSs using metagenomics assembly. Additionally, the biofilm activity and viability were monitored based on adenosine triphosphate (ATP) and flow cytometer (FCM) staining. The results showed that both chlorine and chloramine disinfectants decreased biofilm ATP, although chloramine at a lower dosage (1 mg/L) could increase it. Chloramine caused a greater decrease in living cells than chlorine. Furthermore, the disinfectants significantly lowered the microbial community diversity and altered microbial community structure. Certain bacterial taxa were enriched, such as Mycobacterium, Sphingomonas, Sphingopyxis, Azospira, and Dechloromonas. Pseudomonas aeruginosa exhibited high resistance towards disinfectants. The disinfectants also decreased the complexity of microbial community networks. Some functional taxa (e.g., Nitrospira, Nitrobacter, Nitrosomonas) were identified as keystones in chloramine-treated DWDS microbial ecological networks. Stochasticity drove biofilm microbial community assembly, and disinfectants increased the contributions of stochastic processes. Chlorine had greater promotion effects on antibiotic resistance genes (ARGs), mobile genetic elements (MGEs) and ARG hosts than chloramine. The disinfectants also selected pathogens, such as Acinetobacter baumannii and Klebsiella pneumonia, and these pathogens also harbored ARGs and MGEs. Overall, this study provides new insights into the effects of disinfectants on biofilm microbiome and antibiotic resistome, highlighting the importance of monitoring and managing disinfection practices in DWDSs.

Chlorination of Emerging Contaminants for Application in Potable Wastewater Reuse: Disinfection Byproduct Formation, Estrogen Activity, and Cytotoxicity.

With increasing water scarcity, many utilities are considering the potable reuse of wastewater as a source of drinking water. However, not all chemicals are removed in conventional wastewater treatment, and disinfection byproducts (DBPs) can form from these contaminants when disinfectants are applied during or after reuse treatment, especially if applied upstream of advanced treatment processes to control biofouling. We investigated the chlorination of seven priority emerging contaminants (17ß-estradiol, estrone, 17α-ethinylestradiol, bisphenol A (BPA), diclofenac, p-nonylphenol, and triclosan) in ultrapure water, and we also investigated the impact of chlorination on real samples from different treatment stages of an advanced reuse plant to evaluate the role of chlorination on the associated cytotoxicity and estrogenicity. Many DBPs were tentatively identified via liquid chromatography (LC)- and gas chromatography (GC)-high resolution mass spectrometry, including 28 not previously reported. These encompassed chlorinated, brominated, and oxidized analogs of the parent compounds as well as smaller halogenated molecules. Chlorinated BPA was the least cytotoxic of the DBPs formed but was highly estrogenic, whereas chlorinated hormones were highly cytotoxic. Estrogenicity decreased by ∼4-6 orders of magnitude for 17ß-estradiol and estrone following chlorination but increased 2 orders of magnitude for diclofenac. Estrogenicity of chlorinated BPA and p-nonylphenol were ∼50% of the natural/synthetic hormones. Potential seasonal differences in estrogen activity of unreacted vs reacted advanced wastewater treatment field samples were observed.

N-nitrosamines induced gender-dimorphic effects on infant rats at environmental levels.

The safety of drinking water has always been a concern for people all over the world. N-nitrosamines (NAs), a kind of nitrogenous disinfection by-products (N-DBPs), are generally detected as a mixture in drinking water at home and abroad. Studies have shown that individual NAs posed strong carcinogenicity at high concentrations. However, health risks of NAs at environmental levels (concentrations in drinking water) are still unclear. Therefore, the potential health risks of environmentally relevant NAs exposure in drinking water needs to be conducted. In this study, blood biochemical analysis and metabolomics based on nuclear magnetic resonance (NMR) were performed to comprehensively investigate NAs induced metabolic disturbance in infant rats at environmental levels. Results of blood biochemical indices analysis indicated that AST in the serum of male rats in NAs-treated group exhibited a significant gender-specific difference. Multivariate statistics showed that two and eight significantly disturbed metabolic pathways were identified in the serum samples of NAs-treated male and female rats, respectively. In the urine samples of NAs-treated female rats, glycine, serine, and threonine metabolism pathway was significantly disturbed; while three significantly disturbed metabolic pathways were found in the urine of NAs-treated male rats. Finally, results of spearman correlation coefficients suggested that the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota (data derived from our published paper). Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management. ENVIRONMENTAL IMPLICATION: N-nitrosamines (NAs) are a kind of nitrogenous disinfection by-products (N-DBPs) generated during drinking water disinfection processes. Herein, health risks of NAs at environmental levels (concentrations in drinking water) are investigated using blood biochemical analysis and nuclear magnetic resonance (NMR)-based metabolomics. Results confirmed NAs induced gender-specific on the metabolism in rat and the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota. Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management.

Occurrence and Health Risks of Organic Micropollutants in Tap Water in Dalian.

Organic micropollutants (OMPs) in tap water may pose risks to human health. Previous studies on the potential health risks of OMPs in tap water may have underestimated the potential health risks of OMPs due to their limited coverage in target pollutants and incomplete toxicity data. In this study, tap water samples were collected in 37 sampling sites in Dalian, China. More than 1,200 target pollutants were screened by combining screening analysis and target analysis. A total of 93 OMPs were detected, with concentration summation ranging from 157 to 1.7 × 104 ng/L among different sampling sites. A total of 17 OMPs (12 agrochemicals, 3 pharmaceuticals and personal care products, and 2 other compounds) were detected in over 80% of the sampling sites. Especially, imidacloprid, tebuconazole, and atrazine-desethyl were found in all the sampling sites. Computational toxicology models were adopted to predict the missing toxicity threshold values of the identified chemicals. Noncarcinogenic risks were estimated to be negligible among all the sampling sites, while carcinogenic risks at six sites were above 10-6 but below 10-4, indicating non-negligible risks. Griseofulvin contributed the most to the carcinogenic risk. This study offers valuable insights that can guide future initiatives to safeguard tap water safety.

Metabolomic Signatures of Exposure to Nitrate and Trihalomethanes in Drinking Water and Colorectal Cancer Risk in a Spanish Multicentric Study (MCC-Spain).

We investigated the metabolomic profile associated with exposure to trihalomethanes (THMs) and nitrate in drinking water and with colorectal cancer risk in 296 cases and 295 controls from the Multi Case-Control Spain project. Untargeted metabolomic analysis was conducted in blood samples using ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. A variety of univariate and multivariate association analyses were conducted after data quality control, normalization, and imputation. Linear regression and partial least-squares analyses were conducted for chloroform, brominated THMs, total THMs, and nitrate among controls and for case-control status, together with a N-integration model discriminating colorectal cancer cases from controls through interrogation of correlations between the exposure variables and the metabolomic features. Results revealed a total of 568 metabolomic features associated with at least one water contaminant or colorectal cancer. Annotated metabolites and pathway analysis suggest a number of pathways as potentially involved in the link between exposure to these water contaminants and colorectal cancer, including nicotinamide, cytochrome P-450, and tyrosine metabolism. These findings provide insights into the underlying biological mechanisms and potential biomarkers associated with water contaminant exposure and colorectal cancer risk. Further research in this area is needed to better understand the causal relationship and the public health implications.

[Health risk assessment of heavy metals and metalloid in drinking water in a region of Huaihe River Basin from 2015 to 2019].

OBJECTIVE: To evaluate the chronic health risk of heavy metals and metalloid in drinking water through oral ingestion in a typical area. METHODS: Monitoring data of seven heavy metals and metalloid elements(Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd) in drinking water in a typical area of Huaihe River Basin were collected from 2015 to 2019. The health risks of heavy metals and metalloid in drinking water in the area were assessed using the classic four-step health risk assessment model. RESULTS: The average concentrations of Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd in drinking water in the typical area of Huaihe River Basin were(0.13±0.45), (0.49±0.49), (0.34±0.99), (1.10±2.49), (32.29±126.64), (2.13±0.50) and(0.03±0.04) µg/L, respectively. In which, Hg, Mn and Ni exceeded the limit of the Standard for Drinking Water(GB 5749-2006), the exceedance rates were 2.14%, 6.79% and 0.3%, respectively, and the maximum exceedance times were 2.61, 8.90 and 0.34, respectively. The chronic non-carcinogenic risks of Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd were 1.32×10~(-2), 4.99×10~(-2), 2.97×10~(-3), 1.68×10~(-3), 7.04×10~(-3), 2.17×10~(-2) and 1.83×10~(-3), respectively. The carcinogenic risks of As, Pb, Cr~(6+) and Cd were 2.24×10~(-5), 8.82×10~(-8), 3.25×10~(-5) and 5.86×10~(-7), respectively. CONCLUSION: Hg, Mn and Ni in drinking water exceeded the standard in a typical area of Huaihe River Basin from 2015 to 2019. The chronic non-carcinogenic risks of Hg, As and other 7 heavy metals and metalloid are at an acceptable level(HQ≤1), while As and Cr~(6+) have certain carcinogenic risks(10~(-6)≤CR≤10~(-4)).

Assessment of natural radioactivity in Moroccan bottled drinking waters using gamma spectrometry.

Radioactive elements and their impact on the environment and the food chain, including humans, are a matter of major concern, for which appropriate investigations should be performed. The priority is to examine the concentration of radioactive substances in mineral and bottled spring water. This task aims to analyze the quality of 12 conditioned mineral waters by determining their main radionuclides concentrations, such as 238U, 232Th, and 40K. The identification and the quantification of these radionuclides are carried out by their progeny (except the 40K) by using a NaI(Tl) detector coupled with a multichannel analyzer (MCA) and connected to a computer. The activity measured in all samples varied from 0.95 to 3.38 mBq.L-1 with an average of 1.94 mBq.L-1; from 1.55 to 3.56 mBq.L-1 with an average of 2.46 mBq.L-1; and from 200.68 to 269.19 mBq.L-1 with an average of 236.6 mBq.L-1, for 238U, 232Th, and 40K, respectively. To compare the combined radiological effects of radionuclides present in water, a particular factor Ra(eq) is used. This study showed that the maximum value of Ra(eq) is 27.54 mBq.L-1, which is far below the activity limit of 370 mBq.year-1 set by the Organization of Economics and Development (OECD). Concerning the effective annual dose, the following maximums were measured: 1.61 µSv.year-1, 1.133 µSv.year-1, and 0.925 µSv.year-1 for infants, children, and adults, respectively. These values are even smaller than the dose recommended by the WHO which is 100 µSv.year-1. Regarding the excess lifetime cancer risk index, a maximum of 5.63 × 10-6 is found. This index value is still less than that proposed by James, namely 2.5 × 10-3. Thus, the quality of the studied samples respects the radiological international safety and health limits.

Potential and mechanism of disinfection by-products removal in drinking water by bubbling corona discharge.

Disinfection by-products (DBPs) with significant teratogenic and carcinogenic properties have become a growing concern among the public. As an efficient and environmentally friendly technology, non-thermal plasma offers potential for removing emerging micro-pollutants. In this study, the degradation performance of bubbling corona discharge was evaluated on 24 halogenated alicyclic and aliphatic DBPs present in drinking water at concentrations ranging from ng/L to µg/L. The degradation of DBPs followed pseudo-first-order kinetics with rate constants (kobs) in the descending order of halonitromethanes (HNMs), halogenated benzoquinones (HBQs), haloacetonitriles, trihalomethanes (THMs), haloketones, halogenated aldehydes, and haloacetic acids (HAAs). THMs, HNMs, and HBQs were effectively removed within 5 min under a discharge power of 28 W. Degradation rates achieved by plasma treatment surpass those of other conventional treatment technologies. The required energy consumption was in the range of 5-30 kW·h/m3/order. Furthermore, the study investigated the effects of discharge power, initial concentration, and economic analysis on the degradation of four selected DBPs as representatives of mono-, di- and multi-carbon-containing DBPs, namely chloroform (TCM) and bromoform (TBM), tribromoacetic acid (TBAA), and 2,3,5,6-tetrachloro-1,4-benzoquinone (TetraC-BQ). Reactive radicals in the plasma system were investigated using electron paramagnetic resonance, optical emission spectroscopy, fluorimetry, and radical scavengers. Hydrated electrons and hydroxyl radicals played an important role in the removal of DBPs. The intermediates generated during the degradation of TCM, TBM, TBAA, and TetraC-BQ were identified, and the possible degradation pathways for mono- and binary C-DBPs and HBQs were deduced. The breakdown of HBQs did not produce secondary contamination with aliphatic DBPs. The carbon in DBPs was primarily converted to formic acid, acetic acid, and oxalic acid, and the halogens were mainly converted to halogen ions. Additionally, luminescent bacteria toxicity testing confirmed that plasma treatment could reduce the acute toxicity of water samples. These findings demonstrate the potential of plasma treatment as a post-treatment device at the household level.

Exposure to micro(nano)plastics polymers in water stored in single-use plastic bottles.

Human exposure to micro (nano)plastics (MNPLs) has become a significant concern as a potential health threat. Exposure routes include ingestion, inhalation, and dermal contact, being food and drinking water the primary sources of oral exposure. Here we present the quantification of polymers of MNPLs particles from 700 nm to 20 µm in bottled water commercialised in Spain, including an estimation of the potential risk for daily consumers. We evaluated samples from 20 popular brands in 0.5 and 1.5 L plastic bottles. A double-suspect screening approach developed and validated in our research group for drinking water was adapted for bottled water samples. The identification and quantification of MNPLs-polymers in mass units and the tentative identification of plastic additives (PA) until the second level of confidence was carried out based on high-performance liquid chromatography coupled to high-resolution mass spectrometry (HPLC-HRMS). The results showed the presence of polypropylene (PP), polyethylene (PE) and polypropylene terephthalate (PET) in the samples. Among them, PE was the most frequently detected and quantified polymer (55% of samples) followed by PET which was detected in 33% of the samples and showing the highest concentration (4700 ng L-1). The median value of the sum of polymer concentrations was 359 ng L-1. In addition, 28 plastic additives were detected, where at least one of them was present in 100% of the samples. Stabilizers and plasticisers were the most frequently identified. A prioritisation study was performed using a multi-QSAR modelling software, where bis(2-ethylhexyl) adipate and bis(2-ethylhexyl) phthalate were estimated as the most potentially harmful compounds for human health. Overall, findings suggest that bottled water is a non-negligible route to exposure to MNPLs.

Machine learning approach for assessment of arsenic levels using physicochemical properties of water, soil, elevation, and land cover.

Groundwater is an essential resource; around 2.5 billion people depend on it for drinking and irrigation. Groundwater arsenic contamination is due to natural and anthropogenic sources. The World Health Organization (WHO) has proposed a guideline value for arsenic concentration in groundwater samples of 10[Formula: see text]g/L. Continuous consumption of arsenic-contaminated water causes various carcinogenic and non-carcinogenic health risks. In this paper, we introduce a geospatial-based machine learning method for classifying arsenic concentration levels as high (1) or low (0) using physicochemical properties of water, soil type, land use land cover, digital elevation, subsoil sand, silt, clay, and organic content of the region. The groundwater samples were collected from multiple sites along the river Ganga's banks of Varanasi district in Uttar Pradesh, India. The dataset was subjected to descriptive statistics and spatial analysis for all parameters. This study assesses the various contributing parameters responsible for the occurrence of arsenic in the study area based on the Pearson correlation feature selection method. The performance of machine learning models, i.e., Extreme Gradient Boosting (XGBoost), Gradient Boosting Machine (GBM), Decision Tree, Random Forest, Naïve Bayes, and Deep Neural Network (DNN), were compared to validate the parameters responsible for the dissolution of arsenic in groundwater aquifers. Among all the models, the DNN algorithm outclasses other classifiers as it has a high accuracy of 92.30%, a sensitivity of 100%, and a specificity of 75%. Policymakers can utilize the accuracy of the DNN model to approximate individuals prone to arsenic poisoning and formulate mitigation strategies based on spatial maps.