World Health Organization Guideline Value Research Articles

Local electrochemical sample acidification for the detection of Pb2+ traces.

Electrochemical detection of pollutants (e.g. heavy metals) in real samples often requires the adjustment of pH to allow optimal sensitivity. Such sample pretreatment can be challenging for on-site applications as it implies the use of valves, pumps and storage of base or acid solutions. We report here the use of an electrochemical approach for the control of water sample pH. It offers the possibility for local pH adjustment while simultaneously detecting Pb2+, whose detection sensitivity is pH dependent. An effective electrochemical method through local electrochemical acidification is performed to detect Pb2+ within a desired pH range without the need to add chemical reagents. Local acidification is based on water electrolysis. An anodic potential is applied to an acidifier to rapidly electrogenerate protons. This allows the sample pH to be tailored to the optimal detection condition. Reduction of the Pt oxide layer formed on the acidifier is key to obtain repeatable results in Pb2+ detection. On-site sample acidification is combined with anodic stripping voltammetry to reach a detection limit of 6 ppb (30 nM), which is lower than the World Health Organization guideline value for Pb2+ level in drinking water.

Comparative investigation of known and unknown disinfection by-product precursor removal and microbial community from biological biochar and activated carbon filters

Biological activated carbon filter (BAC) is one of the most effective technologies for removing disinfection by-product (DBP) precursors from water. Biochar is a lower-cost medium that has the potential to replace granular activated carbon in BAC applications, thus leading to the development of biological biochar filter (BCF). This study compared BCF with BAC for the removal of DBP precursors using column experiments. Both BCF and BAC achieved the removal of DBP precursors, resulting in concentrations of all DBP formation potential below the World Health Organization guideline values for drinking water. Bromodichloromethane and unknown DBP precursor removal by BCF was comparable to that by BAC. However, BAC removed more chloroform and dichloroacetontrile precursors than BCF. For microbial community analysis, cell numbers in a bottom layer (inlet) of BCF and BAC columns were higher than those in the top layer. The abundances of Nordella and a microbial genus from Burkholderiaceae at the bottom layer showed a strong correlation to the number of DBP precursors removed and were comparable in BCF and BAC. This finding likely contributes to the similarities between DBPs species removed and the removal performances of some known and unknown DBP precursors by BCF and BAC. Overall results from this study revealed that biochar can be served as a low-cost and sustainable replacement of activated carbon in water filter for DBP precursor removal.

Removal of Fluoride from Water by using Natural Adsorbent

Abstract: Access to safe drinking water is not only the elementary need of human being but also honored as an mortal right .For overall development of the country , as acceptable nutrition, education, gender equivalency, and particularly the eradication of poverty in developing countries are required , along with that furnishing safe drinkable water is equally important . Fluoride one of the water quality parameters of concern, with redundant( beyond1.5 mg/ l, World Health Organization( WHO) guideline value of what contaminates groundwater coffers in numerous corridors of the world, and renders it not drinkable for mortal consumption, due to affiliated adverse health goods thus, knowledge of its junking, using the stylish fashion with optimum effectiveness demanded . Taking the inflexibility of the problem into consideration, the present paper aims to give a retrospective approach to the use of effective low- cost adsorbents for the junking of fluoride from water . The defluoridation capacity of certain low- cost natural adsorbents like Groundnut shell powder and Soya chunk powder were added in the list and discussed. The effect of pH, adsorbent dose, initial concentration , and contact time also delved . It's set up that the junking of Fluoride ions at optimum parameters like pH, adsorbent dose ,initial concentration and contact time is at 7, 2gm, 5mg/ l, and 100 minutes respectively for groundnut shell powder and 6, 2gm, 5mg/ l, and 100 minutes respectively for Soya chunk powder. For all optimum parameters, the maximum reduction in Fluoride ions observed in the range of 55 to 65% for groundnut shell powder whereas for soya chunk powder it's 40 to 50%

Hydrochemistry and Contamination in Sedimentary and Fractured-Rock Aquifers of The Upper Rio Negro Basin – Amazonas/Brazil

The Amazon region has the largest hydrographic network on the planet. However, cities and communities along rivers obtain water from tube wells without studying the chemical quality and, consequently, the potability of their water. In specific geological contexts, there is a significant probability of natural contamination by arsenic in groundwater in the region, already attested in previous works in the Solimões, Madeira and Amazonas rivers basins, but not yet found in the Negro river basin. As the Negro is the second largest river in the Amazon Basin, it has become necessary to study the chemical quality of its groundwater, relating it to the geology of the region. In this work, water samples were collected from 21 wells and 4 water springs used for human consumption, following the protocols proposed by the US – EPA. In the field, the physicochemical parameters of the in-situ water were measured, and alkalinity tests were carried out on the samples. The cations were analyzed at INPA and the anions at the Geological Survey of Brazil (SGB). From the 25 samples, 16 had analises results within acceptable ionic balance values, and 12 of the 16 had at least one of the following elements in concentration above World Health Organization and Brazilian Guideline Values: Al, As, Fe, Mn and Pb. The presence of values below the GV, but above what is considered natural, of NO3- in 66% of the contaminated points, associated with the shallow depth of most of the wells, installed in areas of recent sedimentary deposits and that do not show any or few signs of care demonstrate that the contamination in these localities is of anthropic origin. Two samples (16% of the contaminated samples) are from deep wells installed in fractured aquifers, which in this case indicate contamination of geogenic origin. Arsenic was found in association with iron and aluminum in a well installed in alluvial sediments, which indicates that more studies are needed for this specific geologic formation to know the quality of this water. For other locations and cities, short, medium and long-term measures are needed to prevent anthropogenic contamination of aquifers.

Assessment of nitrate contamination of domestic wells and remedial treatment by electrocoagulation

Natural water contaminated with nitrates can pose serious problems for human health and aquatic ecosystems. Thus, effective, and low-cost treatment systems that can be implemented on both large and small scales are needed. The main goals of this work were to quantify nitrate pollution of groundwater (i.e., underground well water used for drinking purposes), to identify its causes, to evaluate the performance of the electrocoagulation (EC) process in nitrate removal, optimizing the treatment procedure using synthetic water, and to estimate the process cost. A total of thirty domestic wells, located in Sidi Bel Abbes city in North-West Algeria, used for drinking water were subject to sampling. Results indicated that most of the wells had nitrate contents that exceeded the World Health Organization (WHO) guideline value as well as the Algerian permissible limit of 50 mg.L−1, with a maximum NO3- concentration of 162 mg.L−1. The pollution was presumed to be due to agricultural activity, human and animal waste, and the nature of the soil. The EC treatment tests with aluminum electrodes exhibited a high nitrate removal efficiency of 90% at a current density of 5.12 mA.cm−2, electrolysis time 15 min, pH 8.8, agitation speed 400 rpm and at an initial nitrate concentration of 50 mg.L−1. Under optimum operating conditions, nitrate removal was 88% for an initial [NO3-] of 87 mg.L−1 in groundwater. The operating cost was estimated at 0.27 US $/m3 or 0.12 US $/Kg nitrate removed. The findings from this study showed that EC is an economically viable technique for dealing with nitrate contamination for small-scale water treatment applications.

Evaluation of water quality via determination of trihalomethanes in water distribution networks of Riyadh city in Kingdom of Saudi Arabia

Trihalomethane (THM) has been classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC). This study was conducted to assess the levels of trihalomethane compounds in the Riyadh city water network in two different years (2015 and 2020) and to understand the factors affecting the formation of these compounds. The study covered 15 sites in Riyadh city, distributed between the north, south, east, west and middle of the city. The results of the study indicated that the sum of the ratio of the concentration of each THM compound to its respective World Health Organization(WHO) guideline value not exceed 1 (unitless) where the combined toxicity of all total trihalomethanes THMs concentrations did not exceed the permissible limits, with values ranging between 0.01 and 0.24 at all study sites. These results were less than the recommended guide values form WHO for individual maximum concentrations of each of the THM in water for human consumption. In addition, the average concentration of free chlorine was 0.04 ppm and 0.09 ppm in 2015 and 2020, respectively, indicating that the disinfection had evolved in 2020 compared to 2015. Moreover, there was a weak relationship between trihalomethane formation and the presence of bromide ions and organic carbon, whereas a positive correlation was observed with free chlorine and pH values. The concentration of heavy metals such as cadmium, arsenic, cobalt and chromium were analysed by inductively coupled plasma-optical emission spectroscopy. The results indicated that all heavy metals were within the standard limits: the maximum values were 123 ppb in 2015 and 70.39 ppb in 2020, with lead having the lowest concentration and aluminium having the highest concentration in both years. Furthermore, the ion chromatography results of the cations (sodium Na±, potassium K±, calcium Ca2+and magnesium Mg2+) and the anions (fluoride F-, bromide Br-, chloride Cl-, sulphate SO42- and nitrate NO3–) indicated that the water in this study was suitable for human consumption based on the WHO regulation and the Ministry of Environment, Water and Agriculture (MEWA) standards for drinking water.

Depthwise evaluation of total dissolved solids and arsenic from a drilled borehole near River Ravi, Lahore, Pakistan

Abstract Groundwater pollution is now a significant threat to the ecosystem. The untreated disposal of municipal and industrial wastes through drains into water bodies (rivers, lakes, and canals) is the primary source of contamination. The highly contaminated water harms individual health. In this study, total dissolved solids (TDS) and arsenic (As) mobilization were explored depthwise from a drilled borehole at main Raiwind Road, Thokar Niaz Baig, near River Ravi, Lahore. The concentrations of TDS and As in the aquifer indicate that the top shallow aquifer bearing high salts occurred due to local inputs of waste effluents discharged into the River Ravi. In contrast, at deep shallow aquifers, enrichment of As with elevated pH results from the geochemical oxidative dissolution process. The results showed that natural and anthropogenic activities influence groundwater throughout the depth. The TDS and As concentrations were found above the World Health Organisation (WHO) guideline values at some depth intervals, which are harmful to human health.

Health protection and climate change require ambitious limit values for air pollutants in Europe : Opinion on the revision of the Directive on Air Quality and Clean Air for Europe of the Environmental Public Health commission of the Robert Koch Institute and the Federal Environment Agency

Based on scientific findings, the World Health Organization (WHO) has recommended stricter guideline values for air quality in 2021. Significant reductions in the annual mean values of particulate matter (particle size 2.5 µm or smaller, PM2.5) and long-term exposure to nitrogen dioxide (NO2) and ozone (O3) were put forward. The risk of mortality already increases above the WHO guideline values, as shown in studies investigating low concentrations of air pollutants. In Germany, the 2021 WHO guideline values for PM2.5 and NO2 were clearly exceeded in 2022.In this position paper we give the following recommendations for the European Air Quality Directive: (1)set binding limit values according to WHO 2021, (2)apply the limit values to the whole of Europe, (3)continue and expand the established country-based monitoring networks, (4)expand air quality measurements for ultrafine particles and soot particles, and (5)link air pollution control and climate protection measures.Stricter limits for air pollutants require societal and political changes in areas such as mobility, energy use and generation, and urban and spatial planning. Implementation according to WHO 2021 would lead to anet economic benefit of 38billion euros per year.Ambitious limit values for air pollutants also have an impact on climate change mitigation and its health impacts. The Environmental Public Health commission concludes that more ambitious limit values are crucial to enable effective health protection in Germany and calls for air pollutant limit values in line with the 2021 WHO recommendations to become binding in Europe.

Assessment of fluoride exposure and associated health risks from different sources of drinking water to various age groups in Bathinda City, Punjab, India

The presence of elevated fluoride levels in Bathinda City, Punjab, India, has been a major health concern for residents. Previous studies have primarily focused on groundwater but have neglected other drinking water sources. The primary aims of this investigation are to analyze fluoride levels in various drinking water sources in Bathinda City, establish their relationship with physicochemical parameters, and appraise the non-carcinogenic health hazards associated with fluoride exposure for various age categories. A total of 296 water samples were collected, including groundwater (GW), surface water (SW), public water supply (PWS), bottled water (BW), private reverse osmosis water (PROW), municipal reverse osmosis water (MROW) (pre-and post-monsoon), and rainwater (RW). Fluoride levels were determined using a photometer (model: HI97739; make: Hanna Instruments) employing the SPADNS colorimetric procedure. The mean fluoride levels in different water sources were as follows: GW (3.77 mg L−1), SW (0.76 mg L−1), PWS (1 mg L−1), BW (1.4 mg L−1), PROW (0.94 mg L−1), MROW (pre-monsoon) (1.62 mg L−1), MROW (post-monsoon) (1.29 mg L−1), and RW (0.63 mg L−1). A significant proportion of GW (78.4%), PWS (14.3%), BW (37.5%), PROW (25%), and MROW (72.1% in pre-monsoon and 27.9% in post-monsoon) samples surpassed the World Health Organization guideline value. The study findings highlight the high fluoride levels in GW, BW, PROW, and MROW, making them hazardous for consumption. Hazard quotient analysis suggests that children face the highest risk of non-carcinogenic health effects from fluoride exposure, followed by teenagers, adults, senior citizens, and infants.

Threat of air pollution in the cleanest plateau

Threat of air pollution in the cleanest plateau

Factors affecting indoor environmental air quality of non-smoking residences in Perth, Western Australia

This study investigated associations between a range of indoor air pollutants with household characteristics in 111 non-smoking residences located in Perth, Western Australia. Overall, the mean 24-hour indoor concentrations for PM10 and PM2.5 were below and above the World Health Organisation (WHO) (ambient) guideline values (GV) of 45 µg/m3 and 15 µg/m3, respectively. Concentrations of measured gases were low, other than nitrogen dioxide (NO2) which recorded a mean 24-hour concentration above the WHO GV (0.013ppm). Higher concentrations of total volatile organic compounds (TVOC) and carbon dioxide (CO2) were observed as the number of household occupants increased. The type of heating and/or cooling appliances used was associated with higher concentrations of TVOC, CO2, carbon monoxide (CO), NO2 and all size fractions of particulate matter (PM). Households that were opened daily for fresh air recorded higher concentrations of all PM size fractions and NO2 when compared to those that were infrequently aired. These findings contribute to a better understanding of household characteristics that influence indoor air quality (IAQ) in homes where cigarette smoke, a significant contributor to residential air pollution, has been eliminated. These results are useful for modifying some behavioural choices by home occupants and can also inform meaningful risk mitigation strategies aimed at improving IAQ in residential settings.

Prenatal nitrate exposure from diet and drinking water and timing of puberty in sons and daughters: A nationwide cohort study

BackgroundIn Western countries, age at pubertal development has declined during the last century in girls, and probably also in boys. No studies have investigated whether nitrate, a widespread environmental exposure with teratogenic and hormone disrupting properties, might affect timing of puberty. ObjectivesWe investigated if prenatal exposure to nitrate from drinking water and diet was associated with timing of puberty. MethodsThis cohort study included 15,819 children born from 2000 to 2003 within the Danish National Birth Cohort. Self-reported information on current status of various pubertal milestones was provided every six months by a questionnaire from 11 years of age until 18 years or full maturity, whichever came first. Maternal nitrate intake from diet (mg/day) was derived from a mid-pregnancy food frequency questionnaire and individual level nitrate exposure from drinking water (mg/L) was derived using measurements from Danish public waterworks. Adjusted average differences in months in age at attaining several pubertal milestones as well as the average age difference in age at attaining all the milestones were estimated separately for diet and water using a regression model for interval-censored data. C- and E-vitamin, red meat and processed meat intake were explored as potential effect modifiers in sub-analyses. ResultsNo strong associations were observed between prenatal exposure to nitrate and timing of puberty in children. However, sons born of mothers with a nitrate concentration in drinking water at their residential address of > 25 mg/L (half of the World Health Organisation (WHO) guideline value) compared with ≤ 1 mg/L showed a tendency towards earlier age at pubertal development with an average age difference of −1.2 months (95 % confidence interval,−3.0;0.6) for all the pubertal milestones combined. DiscussionStudies including more highly exposed children are needed before the current WHO drinking water guideline value for nitrate can be considered safe concerning pubertal development.

Health and economic gain attributable to the introduction of the World Health Organization's drinking water standard on arsenic level in Hungary: A nationwide retrospective study on cancer occurrence and ischemic heart disease mortality

The World Health Organization (WHO) estimates that 140 million individuals are at risk from consumption of drinking water containing arsenic at concentrations above the WHO guideline value of 10 μg/l. Arsenic mitigation is considered to be the most effective way to prevent arsenic related diseases. After joining the European Union, Hungary implemented a Drinking Water Quality Improvement Programme (DWQIP) to reduce levels of arsenic in drinking water below the WHO guideline value. But what impact did this have on health? We estimated the change in lifetime excess skin, lung, and bladder cancer risks and mortality from ischaemic heart disease (IHD) associated with chronic arsenic intake among those exposed before (2004–2007) and after (2014–2017) the implementation of DWQIP. A population-based risk assessment approach was used to assess lifetime excess cancer risk applying two scenarios for lung and bladder cancers. The economic benefits of the DWQIP were estimated by the combination of cost of illness and value per statistical life methods. Compared to the period before the DWQIP, its implementation was associated with a significant reduction in arsenic in drinking water [median: 3.0 μg/l interquartile range (IQR): 1.5–12.0 μg/l to median: 2.15 μg/l IQR: 1.0–5.79 μg/l]. The two scenarios were estimated to be associated with 225.2 and 35.9 fewer cancer cases each year. The number of annually prevented IHD deaths was estimated to be 88.9. It was estimated that the benefits of the DWQIP will outweigh its costs. We conclude that reducing arsenic levels in drinking water to 10.0 μg/l resulted in significant health and economic benefits. Our study goes beyond the existing research, offering both new insights into the impact of arsenic mitigation and providing a methodological template for similar studies in the many parts of the world that have yet to reduce arsenic exposure.

Mercury Pollution from Artisanal and Small-Scale Gold Mining in Myanmar and Other Southeast Asian Countries.

Mercury (Hg) is one of the most harmful metals and has been a public health concern according to the World Health Organization (WHO). Artisanal and small-scale gold mining (ASGM) is the world’s fastest-growing source of Hg and can release Hg into the atmosphere, hydrosphere, and geosphere. Hg has been widely used in ASGM industries throughout Southeast Asia countries, including Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, and Thailand. Here, 16 relevant studies were systematically searched by performing the PRISMA flow, combining the keywords of “Hg”, “ASGM”, and relevant study areas. Mercury concentrations exceeding the WHO and United States Environmental Protection Agency guideline values were reported in environmental (i.e., air, water, and soil) and biomonitoring samples (i.e., plants, fish, and human hair). ASGM-related health risks to miners and nonminers, specifically in Indonesia, the Philippines, and Myanmar, were also assessed. The findings indicated severe Hg contamination around the ASGM process, specifically the gold-amalgamation stage, was significantly high. To one point, Hg atmospheric concentrations from all observed studies was shown to be extremely high in the vicinity of gold operating areas. Attentions should be given regarding the public health concern, specifically for the vulnerable groups such as adults, pregnant women, and children who live near the ASGM activity. This review summarizes the effects of Hg in Myanmar and other Southeast Asian countries. In the future, more research and assessment will be required to investigate the current and evolving situation in ASGM communities.

A novel water-soluble flavonol-based fluorescent probe for highly specific and sensitive detection of Al3+ and its application in onion and zebrafish

A novel and simple turn-on fluorescence probe (HD) for Al3+ detection was successfully developed based on flavonol derivatives. This probe exhibited a significantly enhanced fluorescence response toward Al3+ in aqueous solution which could be observed by naked-eye from poor fluorescence to strong light green emission. The probe HD displays highly specific detection for Al3+ over other competitive metal ions, and the detection limit of probe HD for Al3+ was determined to be 2.57 × 10−8 M, which are much lower than the World Health Organization (WHO) guideline value for drinking food/water. The binding stoichiometry of probe HD with Al3+ was determined to be 1:1 according to Job’s plot and ESI-HRMS analysis, and the binding constant was calculated to be 2.01 × 104 M−1. The probe HD exhibited high selectivity, high sensitivity, good anti-interface ability, and wide pH application range as well as the quantitative determination in the detection of Al3+. The coordination mechanism of probe HD with Al3+ was supported by density functional theory (DFT) calculations and HRMS analysis. In addition, the probe HD was found to have good cell permeability and could be applied for live-cell imaging to detect Al3+ in onions and zebrafish.

Assessment of the level of some selected heavy metals and physicochemical in Abzana water samples, Kibet woreda, Ethiopia

This study was conducted to investigate the contamination level of Abzana water in Asano district. Five water samples were collected from different point of Abzana water. Some physicochemical parameters and four heavy metals (Cd, Pb, Cr and Mn) concentration were analyzed using standard procedures, and the results were compared with World Health Organization guideline values. The results of the present study have shown the temperatures of all sampling station range between 18.9 and 19.2 °C. The pH was found to be of range from 6.54 to 7.11, whereas the electrical conductance was 1.745 × 102 to 2.06 × 102 (µS/cm). In addition, the lowest value of total dissolved solids was 1.314 × 102 mg/L and the highest was 1.401 × 102 mg/L. In contrast, four heavy metals were analyzed and compared with standards of drinking water. The results indicate that the mean concentration of Cd (6.64 × 10−3 mg/L) exceeded the standards, but the mean concentration of Mn, Pb and Cr was founds within the standard limit at 7.608 × 10–2, 8.10 × 10–3 and 3.5442 × 10–2 mg/L, respectively. The concentrations of the investigated metal (Cr, Pb and Mn) and all physicochemical result of Abzana water from Asano kebele were found below the guidelines for drinking water. However, the concentration of Cd in Abzana water sample was found above the permissible limit of World Health Organization standards. Therefore, it was not safe for drinking and health effect according metals what we have studied here.

Hydrogeological properties, sources provenance, and health risk exposure of fluoride in the groundwater of Batkhela, Pakistan

This study aimed to determine the fluoride (F − ) concentration, fate distribution, source provenance, geochemistry, and health risk exposure through oral ingestion of groundwater. Therefore, 60 groundwater samples were collected from five areas of sub-district Batkhela viz. Batkhela colony, Pirkhel, Selay Patty, Thana, and, Totai. The range concentrations of F − in the groundwater samples collected from the aforementioned areas were 0.50–2.30, 0.90–2.30, 0.50–2.40, 0.30–1.50, and 1.20–2.40 mg/L, and mean were 1.60, 1.50, 1.60, 0.90, and 1.70 mg/L, respectively. The results of fluoride showed that 28.5% of the groundwater samples exceeded the world health organization (WHO) guideline value of 1.5 mg/L. The chemical facies identified three types of groundwater such as CaHCO 3 (55%), NaHCO 3 (32%), and NaCl (13%). Moreover, alkaline pH high HCO 3 − and Na + concentration, while depleted Ca + + and Mg + + concentration promote F − dissolution in the groundwater aquifer. The principal component analysis and Gibbs plot define that weathering and dissolution of granite rock minerals play a key role in the control of groundwater chemistry. Additionally, the ion exchange process also plays an important role in releasing F − in the groundwater aquifer. Whereas cluster analysis identified three clusters: C1 was less polluted, C2 was moderately polluted, and C3 was a severely polluted cluster and their percentage contribution was 20%, 58%, and 22%, respectively. Health risk assessment of F − for non-cancer risk in males, females, and children shows high health risk exceeded the recommended value of 0.6 for the community. Therefore, the groundwater sources of the study area are unfit for drinking, and domestic purposes. • 28.3% water samples of Batkhela exceeded the WHO guideline values of 1.5 mg/L of F − . • Health risk of F − shows community fluorosis for both adults and children. • Base ion exchange and weathering processes are responsible for F − contamination. • PCA results shows that groundwater contamination was due to known mineral prospects. • CaHCO 3 (55%), NaHCO 3 (32%), and NaCl (13%) were the major water type.

Diurnal variation and potential sources of indoor formaldehyde at elementary school, high school and university in the Centre Val de Loire region of France

Formaldehyde (HCHO) is one of the abundant indoor pollutants and has been classified as a human carcinogen by the International Agency for Research on Cancer (IARC). Indoor HCHO at schools is particularly important due to the high occupancy density and the health effects on children. In this study, high time resolved measurement of formaldehyde concentration was conducted in the classrooms at elementary school, high school and university under normal students' activities in three different locations in the Region Centre Val de Loire-France. Indoor average formaldehyde concentrations at those three educational institutions were observed to be in the range 10.96–17.95 μg/m3, not exceeding the World Health Organization (WHO) guideline value of 100 μg/m3. As expected, ventilation was found playing an important role in the control of indoor formaldehyde concentration. After opening windows for 30 min, formaldehyde level decreased by ~25% and 38% in the classroom at the elementary school and the high school, respectively. In addition to the primary sources, the objective of this study was also to determine potential secondary sources of indoor formaldehyde in these schools by measuring the other volatile organic compounds (VOCs) present in the classrooms by a Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS). The measurements suggest that the release of residue from tobacco smokers is one of the major sources of indoor HCHO at the high school, which increases HCHO by ~55% averagely within 1 h. Moreover, the control experiments conducted in the university suggests that VOCs such as that released from cleaning products like terpenes, can contribute to the increase of indoor formaldehyde levels through chemical reactions with ozone. This study confirms simple recommendations to reduce the indoors HCHO concentration in schools: use ventilation systems, limit the emissions like cigarette smoke or cleaning products. It also points out that the secondary sources of formaldehyde must be also considered in the classroom.

Association of selenium, arsenic, and other trace elements in drinking water and urine in residents of the plateau region in China.

Drinking water is considered to bean important exposure pathway for humans to ingest trace elements; human urine samples are widely accepted as biometric substrates that can reflect human exposure to trace elements. The current study aimed at investigating the concentrations of trace elements including selenium (Se), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in drinking water and human urine in plateau region of China, determining the association among trace elements in drinking water and urine, and analyzing their associations with age and gender. The results showed that the majority of trace element concentrations were in the range of the World Health Organization (WHO 2011) guideline values, in both urine samples of male and female, and the median values were descending in the order: Zn > Cu > As > Se > Cr > Ni > Mn > Pb > Cd > Co. Selenium contributed to the excretion of As, Cr, Cu, Cd, and Zn in human body, group of 31-40years appeared to present the greatest excretion ability in most of the trace elements. Weak positive correlations were observed between age and Mn in female urine samples, and negative correlations were observed between age and Se, As, Co, and Cu in male urine samples and between age and Co in female urine samples, respectively. Significant positive correlation was observed in As between drinking water and the whole human urine. In the same family, female seemed to show higher proportions of urinary As levels than male. This study will provide elementary information regarding trace element levels in drinking water and human urine in residents in plateau region of China and is helpful to provide reference for dietary nutrient trace element intake and effective control for local resident.

Natural and Anthropogenic Controls of Groundwater Quality in Sri Lanka: Implications for Chronic Kidney Disease of Unknown Etiology (CKDu)

Poor groundwater quality in household wells is hypothesized as being a potential contributor to chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. However, the influencing factors of groundwater quality in Sri Lanka are rarely investigated at a national scale. Here, the spatial characteristics of groundwater geochemistry in Sri Lanka were described. The relationships of groundwater quality parameters with environmental factors, including lithology, land use, and climatic conditions, were further examined to identify the natural and anthropogenic controlling factors of groundwater quality in Sri Lanka. The results showed that groundwater geochemistry in Sri Lanka exhibited significant spatial heterogeneity. The high concentrations of NO3− were found in the districts that have a higher percentage of agricultural lands, especially in the regions in the coastal zone. Higher hardness and fluoride in groundwater were mainly observed in the dry zone. The concentrations of trace elements such as Cd, Pb, Cu, and Cr of all the samples were lower than the World Health Organization guideline values, while some the samples had higher As and Al concentrations above the guideline values. Principal component analysis identified four components that explained 73.2% of the total data variance, and the first component with high loadings of NO3−, hardness, As, and Cr suggested the effects of agricultural activities, while other components were primarily attributed to natural sources and processes. Further analyses found that water hardness, fluoride and As concentration had positive correlations with precipitation and negative correlations with air temperature. The concentration of NO3− and water hardness were positively correlated with agricultural lands, while As concentration was positively correlated with unconsolidated sediments. The environmental factors can account for 58% of the spatial variation in the overall groundwater geochemistry indicated by the results of redundancy analysis. The groundwater quality data in this study cannot identify whether groundwater quality is related to the occurrence of CKDu. However, these findings identify the coupled controls of lithology, land use, and climate on groundwater quality in Sri Lanka. Future research should be effectively designed to clarify the synergistic effect of different chemical constituents on CKDu.