A health risk assessment for exposure to trace metals via drinking water ingestion pathway

Spatial analysis and health risk assessment of heavy metals concentration in drinking water resources

The heavy metals available in drinking water can be considered as a threat to human health. Oncogenic risk of such metals is proven in several studies. Present study aimed to investigate concentration of the heavy metals including As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn in 39 water supply wells and 5 water reservoirs within the cities Ardakan, Meibod, Abarkouh, Bafgh, and Bahabad. The spatial distribution of the concentration was carried out by the software ArcGIS. Such simulations as non-carcinogenic hazard and lifetime cancer risk were conducted for lead and nickel using Monte Carlo technique. The sensitivity analysis was carried out to find the most important and effective parameters on risk assessment. The results indicated that concentration of all metals in 39 wells (except iron in 3 cases) reached the levels mentioned in EPA, World Health Organization, and Pollution Control Department standards. Based on the spatial distribution results at all studied regions, the highest concentrations of metals were derived, respectively, for iron and zinc. Calculated HQ values for non-carcinogenic hazard indicated a reasonable risk. Average lifetime cancer risks for the lead in Ardakan and nickel in Meibod and Bahabad were shown to be 1.09 × 10^-3, 1.67 × 10^-1, and 2 × 10^-1, respectively, demonstrating high carcinogenic risk compared to similar standards and studies. The sensitivity analysis suggests high impact of concentration and BW in carcinogenic risk.

Multi-Elements in Source Water (Drinking and Surface Water) within Five Cities from the Semi-Arid and Arid Region, NW China: Occurrence, Spatial Distribution and Risk Assessment

The purpose of this study was to identify the concentration of multi-elements (MEs) in source water (surface and drinking water) and assess their quality for sustainability. A total of 161 water samples including 88 tap drinking waters (DW) and 73 surface waters (SW) were collected from five cities in Xi’an, Yan’an, Xining, Lanzhou, and Urumqi in northwestern China. Eighteen parameters including pH, electrical conductivity (EC), total organic carbon (TOC) total nitrogen (TN), chemical compositions of anions (F⁻, Cl⁻, NO₃⁻, HCO₃⁻, SO₄²⁻), cations (NH₄⁺, K⁺, Na⁺, Ca²⁺, Mg²⁺), and metals (lead (Pb), chromium (Cr), cadmium (Cd), copper (Cu)) were analyzed in the first time at the five cities . The results showed that pH values and concentrations of Cl⁻, SO₄²⁻, Na⁺, K⁺, Ca²⁺, Mg²⁺ and Cd, Cr, Cu in DW were within the permissible limits of the Chinese Drinking Water Quality Criteria, whereas the concentrations of other ions (F⁻, NO₃⁻, NH₄⁺ and Pb) exceeded their permissible values. In terms of the SW, the concentrations of F⁻, Cl⁻, NO₃⁻, SO₄²⁻ were over the third range threshold i.e., water suitable for fishing and swimming of the Surface Water Quality Standards in China. The spatial distributions of most MEs in source water are similar, and there was no clear variation for all ions and metals. The metals in DW may be caused by water pipes, faucets and their fittings. The noncarcinogenic risk of metals in DW for local children are in decreasing order Cr > Cd > Pb > Cu. The carcinogenic risk from Cr exposure was at the acceptable level according to threshold of USEPA. Although the comprehensive index of potential ecological assessment of Cr, Cd, Pb and Cu in SW ranked at low risk level and was in the order of Huang River in Xining > Peaceful Canal in Urumqi > Yan River in Yan’an > Yellow River in Lanzhou, their adverse effects to ecology and human health at a low concentration in local semi-arid and arid areas should not be ignored in the long run.

Trace element concentrations in the groundwater of the Tamiraparani river basin, South India: Insights from human health risk and multivariate statistical techniques

This study investigates the concentration of trace elements in the groundwater of Tamiraparani river basin, South India. 124 groundwater samples were collected representing diverse landuse condition over the study area. The results reveal that the mean concentrations of Fe, Mn, Cu, Cr, Pb, Zn and Ni were 0.269, 0.02, 0.007, 0.007, 0.003, 0.066, and 0.004 ppm respectively. The decreasing trend of trace element content shows the following order: Fe > Zn > Mn > Cu > Cr > Ni > Pb. Significant positive correlation (p < 0.05) is found between most of the variables such as water level and Fe, Pb; EC and Ni; Fe and Pb; Mn and Pb; Cu and Zn, Ni; Cr and Pb; Zn and Ni. The studied trace elements are found below the international drinking water guidelines except Fe, Mn, and Pb. The Empirical Bayesian Kriging (EBK) model is used to interpolate the studied metal concentrations in the groundwater of the study area. A health risk assessment was carried out using exposure dose index (CDI) and hazard quotient (HQ). The CDI values of trace elements for oral and dermal pathways shows the following order of Fe > Zn > Mn > Cu > Cr > Ni > Pb and Fe > Zn > Mn > Cr > Cu > Ni > Pb respectively. The Hazard quotients suggest that the risk of contamination through oral and dermal pathways is feeble as all the elements show values less than one. The multivariate statistical analysis reveals that the source of trace elements in the groundwater is through natural origin except copper, chromium and lead as these contaminants are derived from anthropogenic activities.

Health risk assessment of heavy metal variability in sachet water sold in Ado-Odo Ota, South-Western Nigeria

The sales of sachet water (SW), also known as "pure water" (PW), in Nigeria is a lucrative business. It serves many people, especially low-income earners, by providing a more affordable access to safe drinking water when compared with table water. However, some of the producers of SW do not effectively treat raw water before packaging them for sale. This study investigates the presence and concentrations of heavy metals, such as chromium (Cr), iron (Fe), manganese (Mn), copper (Cu), aluminum (Al), and zinc (Zn) in some samples of SW sold within Ota, Ogun State, Nigeria. Samples of SW from nine different producers were purchased for four consecutive weeks and analyzed to determine the concentrations of these heavy metals in them. Furthermore, health risk indicators, such as chronic daily intake (CDI) and health risk indices (HRI) for children and adults, were calculated separately. The metal concentrations were compared with allowable limits set by the World Health Organization (WHO), Nigerian Industrial Standard (NIS), and the United States Environmental Protection Agency (US EPA). High concentrations of Cr, Fe, and Al were found in all the nine samples and exceeded the maximum allowable limits (MAL) of all the standards considered. However, the concentrations of Zn, Mn, and Cu were within permissible limits. The HRIs of heavy metals were in the order of Cu > Fe > Zn > Mn > Al > Cr, but since the standard limits set for some metals were exceeded, proper and effective treatment is required to safeguard the health of consumers.

Quality of tube well water intended for irrigation and human consumption with special emphasis on arsenic contamination at the area of Punjab, Pakistan

In the present study, the tube well water quality and the associated health risks, emphasizing on arsenic contamination, were investigated in rural and urban samples from Tehsil Mailsi located in Punjab, Pakistan. Arsenic concentrations (μg/L) were ranged from 12 to 448.5 and which exceeded the WHO recommended limit (10 μg/L) in all cases. The calculated average daily dose (3.3 × 10^-0.4 to 1.2 × 10^-0.2 mg/kg day) and hazard quotient (1.1-40) reflected the potential health risk to local population due to tube well water consumption as drinking purpose. Sodium percent (Na%), sodium absorption ratio, residual sodium carbonate, Kelly's index and magnesium absorption ratio were also determined to assess the suitability of tube well water for irrigation purpose. The resulting piper plot revealed the Na-Ca-HCO₃ type water chemistry of the area and generally alkaline environment. The spatial distribution of arsenic in the tube well waters pinpoints the significant contribution of anthropogenic activities to arsenic pollution. Nevertheless, different statistical tools, including principal component analysis, hierarchical cluster analysis and correlation matrices, revealed the contribution of both natural and anthropogenic activities and alkaline type of aquifers toward the high level of arsenic contamination.

Human Health Risk Assessment Applied to Rural Populations Dependent on Unregulated Drinking Water Sources: A Scoping Review

Safe drinking water is a global challenge for rural populations dependent on unregulated water. A scoping review of research on human health risk assessments (HHRA) applied to this vulnerable population may be used to improve assessments applied by government and researchers. This review aims to summarize and describe the characteristics of HHRA methods, publications, and current literature gaps of HHRA studies on rural populations dependent on unregulated or unspecified drinking water. Peer-reviewed literature was systematically searched (January 2000 to May 2014) and identified at least one drinking water source as unregulated (21%) or unspecified (79%) in 100 studies. Only 7% of reviewed studies identified a rural community dependent on unregulated drinking water. Source water and hazards most frequently cited included groundwater (67%) and chemical water hazards (82%). Most HHRAs (86%) applied deterministic methods with 14% reporting probabilistic and stochastic methods. Publications increased over time with 57% set in Asia, and 47% of studies identified at least one literature gap in the areas of research, risk management, and community exposure. HHRAs applied to rural populations dependent on unregulated water are poorly represented in the literature even though almost half of the global population is rural.

Factors Shaping the Human Exposome in the Built Environment: Opportunities for Engineering Control

The "exposome" is a term describing the summation of one's lifetime exposure to microbes and chemicals. Such exposures are now recognized as major drivers of human health and disease. Because humans spend ∼90% of their time indoors, the built environment exposome merits particular attention. Herein we utilize an engineering perspective to advance understanding of the factors that shape the built environment exposome and its influence on human wellness and disease, while simultaneously informing development of a framework for intentionally controlling the exposome to protect public health. Historically, engineers have been focused on controlling chemical and physical contaminants and on eradicating microbes; however, there is a growing awareness of the role of "beneficial" microbes. Here we consider the potential to selectively control the materials and chemistry of the built environment to positively influence the microbial and chemical components of the indoor exposome. Finally, we discuss research gaps that must be addressed to enable intentional engineering design, including the need to define a "healthy" built environment exposome and how to control it.

Groundwater quality in Ghaziabad district, Uttar Pradesh, India: Multivariate and health risk assessment

This study aimed to assess the quality of groundwater and potential health risk due to ingestion of heavy metals in the peri-urban and urban-industrial clusters of Ghaziabad district, Uttar Pradesh, India. Furthermore, the study aimed to evaluate heavy metals sources and their pollution level using multivariate analysis and fuzzy comprehensive assessment (FCA), respectively. Multivariate analysis using principle component analysis (PCA) showed mixed origin for Pb, Cd, Zn, Fe, and Ni, natural source for Cu and Mn and anthropogenic source for Cr. Among all the metals, Pb, Cd, Fe and Ni were above the safe limits of Bureau of Indian Standards (BIS) and World Health Organization (WHO) except Ni. Health risk in terms of hazard quotient (HQ) showed that the HQ values for children were higher than the safe level (HQ = 1) for Pb (2.4) and Cd (2.1) in pre-monsoon while in post-monsoon the value exceeded only for Pb (HQ = 1.23). The health risks of heavy metals for the adults were well within safe limits. The finding of this study indicates potential health risks to the children due to chronic exposure to contaminated groundwater in the region. Based on FCA, groundwater pollution could be categorized as quite high in the peri-urban region, and absolutely high in the urban region of Ghaziabad district. This study showed that different approaches are required for the integrated assessment of the groundwater pollution, and provides a scientific basis for the strategic future planning and comprehensive management.

Statistical analysis of arsenic contamination in drinking water in a city of Iran and its modeling using GIS

In this research, probable arsenic contamination in drinking water in the city of Ardabil was studied in 163 samples during four seasons. In each season, sampling was carried out randomly in the study area. Results were analyzed statistically applying SPSS 19 software, and the data was also modeled by Arc GIS 10.1 software. The maximum permissible arsenic concentration in drinking water defined by the World Health Organization and Iranian national standard is 10 μg/L. Statistical analysis showed 75, 88, 47, and 69% of samples in autumn, winter, spring, and summer, respectively, had concentrations higher than the national standard. The mean concentrations of arsenic in autumn, winter, spring, and summer were 19.89, 15.9, 10.87, and 14.6 μg/L, respectively, and the overall average in all samples through the year was 15.32 μg/L. Although GIS outputs indicated that the concentration distribution profiles changed in four consecutive seasons, variance analysis of the results showed that statistically there is no significant difference in arsenic levels in four seasons.

Assessment risk to children's health due to consumption of cow's milk in polluted areas in Puebla and Tlaxcala, Mexico

This study aimed to determine the heavy metal content in cow's milk produced in areas irrigated with waste water and to evaluate the health risk with daily consumption of milk for children. The sample consisted of four zones in which small farmers were selected and the milk of 160 cows in two seasons of the year. On average, the metals in the milk in decreasing order were 0.36; 0.046; 0.035; 0.029; 0.015; 0.012, and 0.002 mg kg^-1 for Zn, Pb, As, Cu, Cr, Ni, and Cd, respectively. The Pb exceeded the limits allowed by Codex. The values shown in the hazard quotient for the As of more than 1 and HI were higher. On the other hand, the individual risk of cancer showed a descending order As> Cd> Cr> Pb, while the total risk indicated that the combined effect of metals put girls and boys at serious risk.

Medical geology in the framework of the sustainable development goals

Exposure to geogenic contaminants (GCs) such as metal(loid)s, radioactive metals and isotopes as well as transuraniums occurring naturally in geogenic sources (rocks, minerals) can negatively impact on environmental and human health. The GCs are released into the environment by natural biogeochemical processes within the near-surface environments and/or by anthropogenic activities such as mining and hydrocarbon exploitation as well as exploitation of geothermal resources. They can contaminate soil, water, air and biota and subsequently enter the food chain with often serious health impacts which are mostly underestimated and poorly recognized. Global population explosion and economic growth and the associated increase in demand for water, energy, food, and mineral resources result in accelerated release of GCs globally. The emerging science of "medical geology" assesses the complex relationships between geo-environmental factors and their impacts on humans and environments and is related to the majority of the 17 Sustainable Development Goals in the 2030 Agenda of the United Nations for Sustainable Development. In this paper, we identify multiple lines of evidence for the role of GCs in the incidence of diseases with as yet unknown etiology (causation). Integrated medical geology promises a more holistic understanding of the occurrence, mobility, bioavailability, bio-accessibility, exposure and transfer mechanisms of GCs to the food-chain and humans, and the related ecotoxicological impacts and health effects. Scientific evidence based on this approach will support adaptive solutions for prevention, preparedness and response regarding human and environmental health impacts originating from exposure to GCs.

Assessment of groundwater quality and health risk in drinking water basin using GIS

Eğirdir Lake basin was selected as the study area because the lake is the second largest freshwater lake in Turkey and groundwater in the basin is used as drinking water. In the present study, 29 groundwater samples were collected and analyzed for physico-chemical parameters to determine the hydrochemical characteristics, groundwater quality, and human health risk in the study area. The dominant ions are Ca²⁺, Mg²⁺, HCO₃^2-, and SO₄². According to Gibbs plot, the predominant samples fall in the rock-water interaction field. A groundwater quality index (WQI) reveals that the majority of the samples falls under good to excellent category of water, suggesting that the groundwater is suitable for drinking and other domestic uses. The Ca-Mg-HCO₃, Ca-HCO₃, Ca-SO₄-HCO₃, and Ca-Mg-HCO₃-SO₄ water types are the dominant water types depending on the water-rock interaction in the investigation area. Risk of metals to human health was then evaluated using hazard quotients (HQ) by ingestion and dermal pathways for adults and children. It was indicated that As with HQ ingestion >1 was the most important pollutant leading to non-carcinogenic concerns. It can be concluded that the highest contributors to chronic risks were As and Cr for both adults and children.

Distribution and health risk assessment of dissolved heavy metals in the Three Gorges Reservoir, China (section in the main urban area of Chongqing)

The Three Gorges Project (TGP) is the largest hydropower station ever built in the world. A better understanding of the concentrations of heavy metals in the aquatic environment of the Three Gorges Reservoir (TGR) is crucial for national drinking water security and sustainable ecosystem development. To thoroughly investigate the impact of heavy metals on water quality after the impoundment to the maximum level of 175 m in the TGR, the concentrations of the dissolved heavy metals (Cr, Cu, Zn, Cd, Pb, As) were measured in April and August 2015, by inductively coupled plasma mass spectrometry (ICP-MS). (1) Except Zn and Pb, most of the heavy metal concentrations in the water of the TGR reached the level of the National Surface Water Environmental Quality Standards (GB3838-2002) I of China, revealing that the water quality of the TGR was good overall. (2) There were significant positive correlations among the concentrations of Cu, As, and Cd, revealing that they may exhibit similar geochemical behaviors. (3) The spatial distribution of the heavy metal concentrations was diverse and complex. The Zn concentration obviously increased in the rainy season from upstream to downstream in the Yangtze River, while the other heavy metals exhibited no significant changes in their concentrations. The distribution characteristics of the heavy metal concentrations on both sides and the middle of the river were different at different sites. (4) The health risk of the six elements was assessed through a human health risk assessment (HHRA), and the assessment results were lower than the maximum acceptable risk level designed by the US EPA and International Commission on Radiological Protection (ICRP). The HHRA model in the aquatic environment revealed that the risk of non-carcinogenic heavy metals (Cu, Zn, and Pb) was at a negligible risk level of 10^-11∼10^-9 a^-1. At all the study sites, the risk of carcinogenic heavy metals (Cr, Cd, and As) was higher than the risk of non-carcinogenic heavy metals. As was the most important risk factor, followed by Cr. The results of this study hold great significance for a timely understanding of the changing water quality for affected departments to ensure the health of the residents in the TGR area.

Elevated Arsenic and Uranium Concentrations in Unregulated Water Sources on the Navajo Nation, USA

Regional water pollution and use of unregulated water sources can be an important mixed metals exposure pathway for rural populations located in areas with limited water infrastructure and an extensive mining history. Using censored data analysis and mapping techniques we analyzed the joint geospatial distribution of arsenic and uranium in unregulated water sources throughout the Navajo Nation, where over 500 abandoned uranium mine sites are located in the rural southwestern United States. Results indicated that arsenic and uranium concentrations exceeded national drinking water standards in 15.1 % (arsenic) and 12.8 % (uranium) of tested water sources. Unregulated sources in close proximity (i.e., within 6 km) to abandoned uranium mines yielded significantly higher concentrations of arsenic or uranium than more distant sources. The demonstrated regional trends for potential co-exposure to these chemicals have implications for public policy and future research. Specifically, to generate solutions that reduce human exposure to water pollution from unregulated sources in rural areas, the potential for co-exposure to arsenic and uranium requires expanded documentation and examination. Recommendations for prioritizing policy and research decisions related to the documentation of existing health exposures and risk reduction strategies are also provided.

Industrial metal pollution in water and probabilistic assessment of human health risk

Concentration of eight heavy metals in surface and groundwater around Dhaka Export Processing Zone (DEPZ) industrial area were investigated, and the health risk posed to local children and adult residents via ingestion and dermal contact was evaluated using deterministic and probabilistic approaches. Metal concentrations (except Cu, Mn, Ni, and Zn) in Bangshi River water were above the drinking water quality guidelines, while in groundwater were less than the recommended limits. Concentration of metals in surface water decreased as a function of distance. Estimations of non-carcinogenic health risk for surface water revealed that mean hazard index (HI) values of As, Cr, Cu, and Pb for combined pathways (i.e., ingestion and dermal contact) were >1.0 for both age groups. The estimated risk mainly came from the ingestion pathway. However, the HI values for all the examined metals in groundwater were <1.0, indicating no possible human health hazard. Deterministically estimated total cancer risk (TCR) via Bangshi River water exceeded the acceptable limit of 1 × 10^-4 for adult and children. Although, probabilistically estimated 95th percentile values of TCR exceeded the benchmark, mean TCR values were less than 1 × 10^-4. Simulated results showed that 20.13% and 5.43% values of TCR for surface water were >1 × 10^-4 for adult and children, respectively. Deterministic and probabilistic estimations of cancer risk through exposure to groundwater were well below the safety limit. Overall, the population exposed to Bangshi River water remained at carcinogenic and non-carcinogenic health threat and the risk was higher for adults. Sensitivity analysis identified exposure duration (ED) and ingestion rate (IR) of water as the most relevant variables affecting the probabilistic risk estimation model outcome.

Spatial characterization, risk assessment, and statistical source identification of the dissolved trace elements in the Ganjiang River-feeding tributary of the Poyang Lake, China

Surface water samples were collected from 20 sampling sites throughout the Ganjiang River during pre-monsoon, monsoon, and post-monsoon seasons, and the concentrations of dissolved trace elements were determined by inductively coupled plasma-mass spectrometry (ICP-MS) for the spatial and seasonal variations, risk assessment, source identification, and categorization for risk area. The result demonstrated that concentrations of the elements exhibited significant seasonality. The high total element concentrations were detected at sites close to the intensive mining and urban activities. The concentrations of the elements were under the permissible limits as prescribed by related standards with a few exceptions. The most of heavy metal pollution index (HPI) values were lower than the critical index limit, indicating the basically clean water used as habitat for aquatic life. As was identified as the priority pollutant of non-carcinogenic and carcinogenic concerns, and the inhabitants ingesting the surface water at particular site might be subjected to the integrated health risks for exposure to the mixed trace elements. Multivariate statistical analyses confirmed that Zn, As, Cd, and Tl were derived from mining and urban activities; V, Cd, and Pb exhibited mixed origin; and Co, Ni, and Cu mainly resulted from natural processes. Three categorized risk areas corresponded to high, moderate, and low risks, respectively. As a whole, the upstream of the Ganjiang River was identified as the high-risk area relatively.

Arsenic accumulation in rice: Consequences of rice genotypes and management practices to reduce human health risk

Rice is an essential staple food and feeds over half of the world's population. Consumption of rice has increased from limited intake in Western countries some 50years ago to major dietary intake now. Rice consumption represents a major route for inorganic arsenic (As) exposure in many countries, especially for people with a large proportion of rice in their daily diet as much as 60%. Rice plants are more efficient in assimilating As into its grains than other cereal crops and the accumulation may also adversely affect the quality of rice and their nutrition. Rice is generally grown as a lowland crop in flooded soils under reducing conditions. Under these conditions the bioavailability of As is greatly enhanced leading to excessive As bioaccumulation compared to that under oxidizing upland conditions. Inorganic As species are carcinogenic to humans and even at low levels in the diet pose a considerable risk to humans. There is a substantial genetic variation among the rice genotypes in grain-As accumulation as well as speciation. Identifying the extent of genetic variation in grain-As concentration and speciation of As compounds are crucial to determining the rice varieties which accumulate low inorganic As. Varietal selection, irrigation water management, use of fertilizer and soil amendments, cooking practices etc. play a vital role in reducing As exposure from rice grains. In the meantime assessing the bioavailability of As from rice is crucial to understanding human health exposure and reducing the risk.

Evaluation of groundwater and surface water quality and human risk assessment for trace metals in human settlements around the Bosomtwe Crater Lake in Ghana

Geogenic and anthropogenic activities introduce certain metals into the environment which tend to deteriorate the quality of both surface and groundwater in the Bosomtwe Crater Lake and its surroundings. In this study spatio-temporal variations in concentrations and risk assessment of selected trace metals (As, Fe, Pb, Zn, Cr, Cd and Ni) were investigated during the wet and dry seasons for surface and groundwater in selected human settlements around the lake. The levels of As, Cd and Ni were generally small and were below the detection limit of the instrument. The results showed no significant seasonal variations in the mean levels of Pb, Fe, Zn and Cr in water from the Bosomtwe Crater Lake. The hazard quotients and health hazard indices through ingestion and dermal contact of lake and groundwater in towns around the lake for both adults and children gave values which were below the acceptable limit of less than unity (< 1), indicating the absence of non-carcinogenic health risk to the communities. The study however reveals that ingestion of both lake and groundwater from the lake and its surroundings poses carcinogenic risk with regard to the level of Pb and Cr. Hence appropriate control measures and interventions should be put in place to protect the health of the human population in the study area.

A quantitative risk assessment for metals in surface water following the application of biosolids to grassland

During episodic rainfall events, land application of treated municipal sludge ('biosolids') may give rise to surface runoff of metals, which may be potentially harmful to human health if not fully treated in a water treatment plant (WTP). This study used surface runoff water quality data generated from a field-scale study in which three types of biosolids (anaerobically digested (AD), lime stabilised (LS), and thermally dried (TD)) were spread on micro-plots of land and subjected to three rainfall events at time intervals of 24, 48 and 360h following application. Making the assumption that this water directly entered abstraction waters for a WTP without any grassed buffer zone being present, accounting for stream dilution, and modelling various performance scenarios within the WTP, the aim of this research was to conduct a human health risk assessment of metals (Cu, Ni, Pb, Zn, Cd and Cr), which may still be present in drinking water after the WTP. Different dose-response relationships were characterised for the different metals with reference to the lifetime average daily dose (LADD) and the Hazard Quotient (HQ). The results for the LADD show that child exposure concentrations were highest for Cu when the measured surface runoff concentrations from the LS biosolids treatment were used as input into the model. The results for the HQ showed that of all the scenarios considered, Cu had the highest HQ for children. However, values were below the threshold value of risk (HQ<0.01 - no existing risk). Under the conditions monitored, metal concentrations in the biosolids applied to grassland were not considered to result in a risk to human health in surface water systems.

Evaluation of potential human health risk and investigation of drinking water quality in Isparta city center (Turkey)

Isparta city center is selected as a work area in this study because the public believes that the tap water is dirty and harmful. In this study, the city's drinking water in the distribution system and other spring waters which are used as drinking water in this region were investigated from the point of water quality and health risk assessment. Water samples were collected from major drinking water springs, tap waters, treatment plants and dam pond in the Isparta province center. Ca-Mg-HCO3, Mg-Ca-HCO3, Ca-Na-HCO3, Ca-HCO3, Ca-HCO3-SO4 and Ca-Mg-HCO3-SO4 are dominant water types. When compared to drinking water guidelines established by World Health Organization and Turkey, much greater attention should be paid to As, Br, Fe, F, NH4, PO4 through varied chemicals above the critical values. The increases of As, Fe, F, NH4 and PO4 are related to water-rock interaction. In tap waters, the increases of As and Fe are due to corrosion of pipes in drinking water distribution systems. The major toxic and carcinogenic chemicals within drinking water are As and Br for both tap water and spring water. Also, F is the non-carcinogenic chemical for only spring waters in the study area.

Occurrence and health risk assessment of selected metals in drinking water from two typical remote areas in China

The potential contaminations of 16 trace elements (Cr, Mn, Ni, Cu, Zn, As, Cd, Sb, Ba, Pb, Co, Be, V, Ti, Tl, Al) in drinking water collected in two remote areas in China were analyzed. The average levels of the trace elements were lower than the allowable concentrations set by national agencies, except for several elements (As, Sb, Mn, and Be) in individual samples. A health risk assessment model was conducted and carcinogenic and non-carcinogenic risks were evaluated separately. The results indicated that the total carcinogenic risks were higher than the maximum allowed risk level set by most organizations (1 × 10(-6)). Residents in both study areas were at risk of carcinogenic effects from exposure to Cr, which accounted for 80-90 % of the total carcinogenic risks. The non-carcinogenic risks (Cu, Zn, Ni) were lower than the maximum allowance levels. Among the four population groups, infants incurred the highest health risks and required special attention. Correlation analysis revealed significant positive associations among most trace elements, indicating the likelihood of a common source. The results of probabilistic health risk assessment of Cr based on Monte-Carlo simulation revealed that the uncertainty of system parameters does not affect the decision making of pollution prevention and control. Sensitivity analysis revealed that ingestion rate of water and concentration of Cr showed relatively high sensitivity to the health risks.

The influence of chemically enhanced backwash by-products (CEBBPs) on water quality in the coagulation-ultrafiltration process

This study was conducted to investigate the typical types of chemically enhanced backwash by-products (CEBBPs) produced in the chemically enhanced backwash (CEB) process and the influence of CEB parameters on typical CEBBPs in the coagulation-ultrafiltration process. Health risk assessment was applied to assess the potential adverse health effect from exposure to effluent after the optimal CEB. The results indicated that backwash reagent of sodium hypochlorite reacted with organic matter to produce CEBBPs, including 12 species of volatile halogenated organic compounds (VHOCs) and 9 species of haloacetic acids (HAAs) during CEB process. The amount of HAAs was higher than that of VHOCs indicating that the content of primary HAA precursor (hydrophilic organic matter) was high in raw surface water and the coagulation process could not lower the hydrophilic organic matter concentration. After comprehensive consideration of the influence of single factors on the CEBBP formation and membrane cleaning effect, the optimal CEB parameters was 4 min of backwash duration, 120 min of backwash interval, 20 L/(m(2)·h) of backwash flux, and 25 mg/L of reagent concentration. Under the optimum CEB cleaning parameters, the effluent did not pose non-carcinogenic risk to local residents but could pose potential carcinogenic risk.

Drinking and recreational water-related diseases: a bibliometric analysis (1980-2015)

BACKGROUND

Water - related diseases are worldwide health concern. Microbial contamination and contaminant products in water are a source of disease outbreaks and development of cumulative toxic effects. Ensuring safe water is one of the goals to be achieved at the global level. The aim of this study was to assess publications on drinking and recreational water from a health point of view to understand current problems and future research trends in this field.

METHODS

Scopus, the largest scientific electronic database, was used to retrieve related articles and present the results as bibliometric tables and maps. Search query was modified manually using related terms to maximize accuracy.

RESULTS

A total of 2267 publications were retrieved with an average of 16.82 citations per article. The h-index of retrieved articles was 88. Visual mapping showed that E. coli, diarrhea, cryptosporidiosis, fluoride, arsenic, cancer, chlorine, trihalomethane, and H. pylori were most frequently encountered terms in title and abstract of retrieved articles. The number of articles on water microbiology was a significant (P < 0.01) predictor of worldwide productivity of water - related disease publications. Journal of Water and Health ranked first in number of publications with 136 (6.00 %) articles. The United States of America ranked first in productivity with a total of 623 (27.48 %) articles. Germany (15.44 %), India (16.00 %) and China (20.66 %) had the least international collaboration in water-related disease research. Environmental Protection Agency and Centers for Disease Prevention and Control were among top ten productive institutions. In the top ten cited articles, there were three articles about arsenic, one about aluminum, one about trihalomethane, one about nitrate, one about toxoplasmosis, one about gastroenteritis, and the remaining two articles were general ones.

CONCLUSIONS

There was a linear increase in the number of publications on water - related diseases in the last decade. Arsenic, in drinking water is a serious concern. Cryptosporidiosis and other infectious gastroenteritis remain a major health risk of exposure to contaminated water. Increased number of publications from Asian countries was not associated with a high percentage of international collaboration.

Different Choices of Drinking Water Source and Different Health Risks in a Rural Population Living Near a Lead/Zinc Mine in Chenzhou City, Southern China

This study aimed to describe the households' choices of drinking water sources, and evaluate the risk of human exposure to heavy metals via different drinking water sources in Chenzhou City of Hunan Province, Southern China. A cross-sectional face-to-face survey of 192 householders in MaTian and ZhuDui village was conducted. The concentrations of heavy metals in their drinking water sources were analyzed. Carcinogenic and non-carcinogenic risk assessment was performed according to the method recommended by the United States Environmental Protection Agency. In total, 52.60% of the households used hand-pressed well water, and 34.89% used barreled water for drinking. In total, 6.67% of the water samples exceeded the Chinese drinking water standards. The total health risk of five metals is 5.20 × 10(-9)~3.62 × 10(-5). The total health risk of five metals was at acceptable levels for drinking water sources. However, the total risk of using hand-pressed well water's highest value is 6961 times higher than the risk of using tap water. Household income level was significantly associated with drinking water choices. Arsenic (As) and lead (Pb) are priority controlled pollutants in this region. Using safe drinking water (tap water, barreled water and so on) can remarkably reduce the risk of ingesting heavy metals.

Unraveling Health Risk and Speciation of Arsenic from Groundwater in Rural Areas of Punjab, Pakistan

This study determined the total and speciated arsenic (As) concentrations and other health-related water quality parameters for unraveling the health risk of As from drinking water to humans. Groundwater samples (n = 62) were collected from three previously unexplored rural areas (Chichawatni, Vehari, Rahim Yar Khan) of Punjab in Pakistan. The mean and median As concentrations in groundwater were 37.9 and 12.7 µg·L⁻¹ (range = 1.5–201 µg·L⁻¹). Fifty three percent groundwater samples showed higher As value than WHO safe limit of 10 µg·L⁻¹. Speciation of As in groundwater samples (n = 13) showed the presence of inorganic As only; arsenite (As(III)) constituted 13%–67% of total As and arsenate (As(V)) ranged from 33% to 100%. For As health risk assessment, the hazard quotient and cancer risk values were 11–18 and 46–600 times higher than the recommended values of US-EPA (i.e., 1.00 and 10⁻⁶, respectively). In addition to As, various water quality parameters (e.g., electrical conductivity, Na, Ca, Cl⁻, NO₃⁻, SO₄²⁻, Fe, Mn, Pb) also enhanced the health risk. The results show that consumption of As-contaminated groundwater poses an emerging health threat to the communities in the study area, and hence needs urgent remedial and management measures.

Drinking water studies: a review on heavy metal, application of biomarker and health risk assessment (a special focus in Malaysia)

Malaysia has abundant sources of drinking water from river and groundwater. However, rapid developments have deteriorated quality of drinking water sources in Malaysia. Heavy metal studies in terms of drinking water, applications of health risk assessment and bio-monitoring in Malaysia were reviewed from 2003 to 2013. Studies on heavy metal in drinking water showed the levels are under the permissible limits as suggested by World Health Organization and Malaysian Ministry of Health. Future studies on the applications of health risk assessment are crucial in order to understand the risk of heavy metal exposure through drinking water to Malaysian population. Among the biomarkers that have been reviewed, toenail is the most useful tool to evaluate body burden of heavy metal. Toenails are easy to collect, store, transport and analysed. This review will give a clear guidance for future studies of Malaysian drinking water. In this way, it will help risk managers to minimize the exposure at optimum level as well as the government to formulate policies in safe guarding the population.

Human health risk assessment via drinking water pathway due to metal contamination in the groundwater of Subarnarekha River Basin, India

Groundwater samples were collected from 30 sampling sites throughout the Subarnarekha River Basin for source apportionment and risk assessment studies. The concentrations of As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Se, Sr, V and Zn were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The results demonstrated that concentrations of the metals showed significant spatial variation with some of the metals like As, Mn, Fe, Cu and Se exceeding the drinking water standards at some locations. Principal component analysis (PCA) outcome of four factors that together explained 84.99 % of the variance with >1 initial eigenvalue indicated that both innate and anthropogenic activities are contributing factors as source of metal in groundwater of Subarnarekha River Basin. Risk of metals on human health was then evaluated using hazard quotients (HQ) and cancer risk by ingestion for adult and child, and it was indicated that Mn was the most important pollutant leading to non-carcinogenic concerns. The carcinogenic risk of As for adult and child was within the acceptable cancer risk value of 1 × 10(-4). The largest contributors to chronic risks were Mn, Co and As. Considering the geometric mean concentration of metals, the hazard index (HI) for adult was above unity. Considering all the locations, the HI varied from 0.18 to 11.34 and 0.15 to 9.71 for adult and child, respectively, suggesting that the metals posed hazard by oral intake considering the drinking water pathway.

Hand-to-mouth contacts result in greater ingestion of feces than dietary water consumption in Tanzania: a quantitative fecal exposure assessment model

Diarrheal diseases kill 1800 children under the age of five die each day, and nearly half of these deaths occur in sub-Saharan Africa. Contaminated drinking water and hands are two important environmental transmission routes of diarrhea-causing pathogens to young children in low-income countries. The objective of this research is to evaluate the relative contribution of these two major exposure pathways in a low-income country setting. A Monte Carlo simulation was used to model the amount of human feces ingested by children under five years old from exposure via hand-to-mouth contacts and stored drinking water ingestion in Bagamoyo, Tanzania. Child specific exposure data were obtained from the USEPA 2011 Exposure Factors Handbook, and fecal contamination was estimated using hand rinse and stored water fecal indicator bacteria concentrations from over 1200 Tanzanian households. The model outcome is a distribution of a child's daily dose of feces via each exposure route. The model results show that Tanzanian children ingest a significantly greater amount of feces each day from hand-to-mouth contacts than from drinking water, which may help elucidate why interventions focused on water without also addressing hygiene often see little to no effect on reported incidence of diarrhea.

Assessment of carcinogenic and non-carcinogenic risk lead in bottled water in different age groups in Bandar Abbas Ciry, Iran

The presence of heavy metals such as lead in drinking water resources can be dangerous for human because of toxicity and biological accumulation. The consumption of water or food which contains lead in high concentration can lead to prevent from Hemoglobin Synthesis (Anemia) and Kidney diseases. In this present study, the researcher collected 432 samples of bottled water in the popular marks in summer and winter from the surface of Bandar Abbas. The lead concentration was measured by atomic absorption Spectrophotometer in model DR2800 through the Dithizone method. CDI, R and HQ which are caused by lead for adult men, women and children, have been calculated and evaluated through the equations of EPA and WHO. The mean concentration of lead, which is 3.46± 0.47 µg/l, and its range, which is 1.9-17.6 µg/l, are lower than the guideline of WHO (10 µg/l) and MPC of EPA is (15 µg/l). But the 40 samples of the bottled water (9.2%) have the concentration higher than guideline WHO and 8 samples (1.85%) has the concentration higher than the permissible limits of the EPA. CDI in different age groups is as following manner: Children>adult men>adult women. CDI in children is more than twice as much as in the adult men and women. The R of lead for children (24E-7), adult men (11E-7) and for adult women (10E-7) are more than the acceptable level of R in EPA (1E-6) but less than the acceptable level of R in WHO (1E-4). Since HQ of adult men (34E-5), adult women (31E-5) and children (84E-5), is lower than 1, it can be said that the population of Bandar Abbas is in a safe area regarding the HQ of the bottled water's lead.

Analysis of Physiochemical Parameters to Evaluate the Drinking Water Quality in the State of Perak, Malaysia

The drinking water quality was investigated in suspected parts of Perak state, Malaysia, to ensure the continuous supply of clean and safe drinking water for the public health protection. In this regard, a detailed physical and chemical analysis of drinking water samples was carried out in different residential and commercial areas of the state. A number of parameters such as pH, turbidity, conductivity, total suspended solids (TSS), total dissolved solids (TDS), and heavy metals such as Cu, Zn, Mg, Fe, Cd, Pb, Cr, As, Hg, and Sn were analysed for each water sample collected during winter and summer periods. The obtained values of each parameter were compared with the standard values set by the World Health Organization (WHO) and local standards such as National Drinking Water Quality Standard (NDWQS). The values of each parameter were found to be within the safe limits set by the WHO and NDWQS. Overall, the water from all the locations was found to be safe as drinking water. However, it is also important to investigate other potential water contaminations such as chemicals and microbial and radiological materials for a longer period of time, including human body fluids, in order to assess the overall water quality of Perak state.

Evaluation of toxicological risk of foodstuffs contaminated with heavy metals in Swat, Pakistan

This study aimed to assess the concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) in the available foodstuffs (crops, milk and water), their bioaccumulation in human body and potential human health risks in Swat valley, northern Pakistan. Heavy metal concentrations in foodstuffs and human blood (adults (18-above) and children (1-12 years)) were analyzed using atomic absorption spectrometer. The results revealed high level of Mn in foodstuffs followed by Cr>Cu>Zn>Ni>Cd>Pb, which significantly increased the levels of heavy metals in the adult׳s blood as compared to that of children in the order of Cr>Zn>Mn>Ni>Pb>Cu>Cd. Principal component analysis showed that selected foodstuffs were the possible sources of metal contamination in human blood, while correlation analysis revealed that the concentrations of Cr, Cu, Mn, Ni, Pb and Zn in foodstuffs significantly correlated with that in human blood. Moreover, risk assessments for individual metals via foodstuffs were found within safe limits, except for Cd (HQ>1); Whereas, for aggregate multiple metals the risk was calculated as 3.97E+00 (HI>1), in which water and milk were perceived as the greater contributors (81 percent) to HI; while fruits, grains and vegetables contributed 5 percent each, and pulses 4 percent.

Effects of storage temperature and duration on release of antimony and bisphenol A from polyethylene terephthalate drinking water bottles of China

We investigated effects of storage temperature and duration on release of antimony (Sb) and bisphenol A (BPA) from 16 brands of polyethylene terephthalate (PET) drinking water bottles in China. After 1-week storage, Sb release increased from 1.88-8.32 ng/L at 4 °C, to 2.10-18.4 ng/L at 25 °C and to 20.3-2604 ng/L at 70 °C. The corresponding releases for BPA were less at 0.26-18.7, 0.62-22.6, and 2.89-38.9 ng/L. Both Sb and BPA release increased with storage duration up to 4-week, but their releasing rates decreased with storage time, indicating that Sb and BPA release from PET bottles may become stable under long term storage. Human health risk was evaluated based on the worst case, i.e., storage at 70 °C for 4-week. Chronic daily intake (CDI) caused by BPA release was below USEPA regulation, Sb release in one brand exceeded USEPA regulated CDI (400 ng/kg bw/d) with values of 409 and 1430 ng/kg bw/d for adult and children.

Metal concentrations in surface water and sediments from Pardo River, Brazil: human health risks

Pardo River (Brazil) is suffering from an important anthropogenic impact due to the pressure of highly populated areas and the influence of sugarcane cultivation. The objective of the present study was to determine the levels of 13 trace elements (As, Be, Cd, Cr, Cu, Pb, Mn, Hg, Ni, Tl, Sn, V and Zn) in samples of surface water and sediments from the Pardo River. Furthermore, the human health risks associated with exposure to those metals through oral intake and dermal absorption were also evaluated. Spatial and seasonal trends of the data were closely analyzed from a probabilistic approach. Manganese showed the highest mean concentrations in both water and sediments, remarking the incidence of the agricultural activity and the geological characteristics within the basin. Thallium and arsenic were identified as two priority pollutants, being the most important contributors to the Hazard Index (HI). Since non-carcinogenic risks due to thallium exposure slightly exceeded international guidelines (HI>1), a special effort should be made on this trace element. However, the current concentrations of arsenic, a carcinogenic element, were in accordance to acceptable lifetime risks. Nowadays, there is a clear increasing growth in human population and economic activities in the Pardo River, whose waters have become a serious strategic alternative for the potential supply of drinking water. Therefore, environmental monitoring studies are required not only to assure that the current state of pollution of Pardo River does not mean a risk for the riverside population, but also to assess the potential trends in the environmental levels of those elements.

Potential health impact and genotoxicity analysis of drinking source water from Liuxihe Reservoir (P.R. China)

Water from the Liuxihe Reservoir (a source of drinking water for Guangzhou City, P. R. China) was analyzed for semi-volatile organic compounds (SVOCs) and the results were used for a potential health impact assessment and genotoxicity test with the microalgae Euglena gracilis. The SVOCs were tested using USEPA Method 525.2, and the health risk assessment was conducted at a screening level using the hazard quotient (HQ) approach. Alkaline single-cell gel electrophoresis (comet assay) was used to evaluate DNA damage and determine the genotoxicity of the source water. The concentrations of the SVOCs in Liuxihe Reservoir were very low and phthalic acid esters were the main SVOCs present. The mean HQ values of pollutants were all less than one, indicating no risk. However, the lifetime carcinogenic risks (LCRs) were found to be close to the threshold of 1.00E-5. The results show that the water in the Liuxihe Reservoir might pose a potential carcinogenic risk to local residents. The highly concentrated extracts of the water samples could induce DNA damage in the microalgal cells and a dose-effect relationship was identified. These results showed that Liuxihe Reservoir water, as a source of drinking water, could pose a potential LCR to local consumers.

Health risk assessment of heavy metals in the water environment of Zhalong Wetland, China

Concentrations of the Cu, Cd, Cr, As, Zn and Ni in water samples from 272 sampling stations in the water environment of Zhalong Wetland, China were studied. Health risk assessment associated with six heavy metals and metalloid was conducted using health risk assessment model from United States Environmental Protection Agency. It can be concluded that the mean concentrations of Cu, Ni, Zn, As, Cd and Cu were 0.19, 0.45, 0.52, 4.9, 0.12 and 0.24 μg L(-1), respectively. The carcinogenic risk of Cr, As and Cd in the discharged area, experimental area, buffer area and core area were lower than the maximum allowance risk level recommended by International Commission on Radiological Protection (ICRP 5.0 × 10(-5) a(-1)). The non-carcinogenic risks (Cu, Zn, Ni) was also lower than the maximum allowance levels recommended by ICRP. Though it was lower than the level, it was very approaching to maximum acceptable risk level, need to draw attention to the relevant departments.

Arsenic concentration variability, health risk assessment, and source identification using multivariate analysis in selected villages of public water system, Lahore, Pakistan

This paper reports high levels and variability in arsenic (As) levels at locations identified as one of the highest As-contaminated locations in Pakistan. Groundwater pollution related to arsenic has been reported since many years in the areas lying in outskirts of District Lahore, Pakistan. A comparative study is done to determine temporal variations of As from three villages, i.e., Kalalanwala (KLW), Manga Mandi (MM), and Shamki Bhattian (SKB). Seventy-three percent of the 30 investigated samples ranging in depth from 20 to 200 m, show an increasing trend in variations of As concentration over a time span of 4 years and 87% of samples exceeded the WHO standard of 10 μg/L for As while 77% of samples have As concentration >50 μg/L (national standard). Further results indicate that high levels of As is accompanied with increase pH (r = 0.8) favoring desorption of As from minerals at higher pH under oxidizing conditions. For health risk assessment of arsenic, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The residents of the studied areas had toxic risk index in the order of SKB>KLW>MM, with 87% of samples exceeding the typical toxic risk index 1.00 (ranging from 2.3-48.6) which was 83% (ranging from 0.3-41) 4 years before. The results of the present study therefore indicate that arsenic concentrations are increasing in the area, which needs an immediate attention to provide alternate sources of water to save people at risk.

Human health risk assessment of dissolved metals in groundwater and surface waters in the Melen watershed, Turkey

Determination of metal risk levels in potable water and their effects on human health are vital in assessment of water resources. Risk assessment of metals to human health in a watershed, which has not been studied before, is the main objective of the present study. Surface and groundwater sampling was carried out between September 2010 and August 2011 in the Melen Watershed, Turkey, an important drinking water resource for millions of people. Metals were analyzed in the laboratory using inductively coupled plasma. Of the 26 different metals monitored, Al, B, Ba, Cr, Cu, Fe, Mn, Mo and V were found in surface water and As, B, Ba, Cr, Cu, Mn, Mo, V and Zn in groundwater. In groundwater, unitless hazard quotient (HQ) values were 6 for As, 2.7 for Mn and 1 for Zn, while in surface water all metals were below the risk level (HQ < 1). The ingestion risk was found to be higher than the dermal uptake risk. Arsenic mean concentration was observed to be 0.044 mg/L in groundwater. The As carcinogenic risk (CR) value was higher than the internationally accepted risk level (10(-4)) and with maximum ingestion of groundwater the carcinogenic risk was found to be higher in adults than children. These results show that even unpolluted watersheds can pose a risk to human health and that potential carcinogenic impacts should receive more attention.

Public health risk assessment associated with heavy metal and arsenic exposure near an abandoned mine (Kirki, Greece)

The 'Agios Philippos' lead-zinc mine in the Kirki region (NE Greece) is now closed, but its legacy of heavy metal contamination remains at the site. At present, management of the contaminated land is of major concern. The area is in a reclamation process and requires immediate remediation action, whereas human risks need to be carefully evaluated. In order to assess these risks, samples from around the mine were collected and analyzed and a scenario involving the oral, dermal, and inhaled doses of arsenic and heavy metals was formulated. A Monte Carlo approach was undertaken, in order to model the average daily dose and quantify the corresponding hazard index and cancer risk. A toxicological risk was associated with samples collected in the vicinity of the mine (floatation, mine tailings) and a pronounced carcinogenic risk for arsenic was evident at the broader occupational/environmental setting. These findings urge for immediate rehabilitation actions that will mitigate population exposures and promote long-term environmental safety in the area.

Assessing mixed trace elements in groundwater and their health risk of residents living in the Mekong River basin of Cambodia

We investigated the potential contamination of trace elements in shallow Cambodian groundwater. Groundwater and hair samples were collected from three provinces in the Mekong River basin of Cambodia and analyzed by ICP-MS. Groundwater from Kandal (n = 46) and Kraite (n = 12) were enriched in As, Mn, Ba and Fe whereas none of tube wells in Kampong Cham (n = 18) had trace elements higher than Cambodian permissible limits. Risk computations indicated that 98.7% and 12.4% of residents in the study areas of Kandal (n = 297) and Kratie (n = 89) were at risk of non-carcinogenic effects from exposure to multiple elements, yet none were at risk in Kampong Cham (n = 184). Arsenic contributed 99.5%, 60.3% and 84.2% of the aggregate risk in Kandal, Kratie and Kampong Cham, respectively. Sustainable and appropriate treatment technologies must therefore be implemented in order for Cambodian groundwater to be used as potable water.

Probabilistic ecological risk assessment of polycyclic aromatic hydrocarbons in southwestern catchments of the Bohai Sea, China

A probability risk assessment was undertaken to study the individual and combined ecological risks induced by six polycyclic aromatic hydrocarbons (PAHs) both in surface water and sediment from southwestern catchments of the Bohai Sea, China. The actual measured PAH concentrations in water and sediment were compared with toxicity effect data (the 10th percentile of predicted no effect concentration) to calculate the risk quotients (RQs) for an individual PAH. The equilibrium partitioning method was applied to estimate toxicity data in sediment. A method based on the equivalent concentration concept was proposed and applied to assess the combined ecological risk of multiple PAHs. Monte Carlo simulation and bootstrap technique were utilized to calculate the distribution of RQs and associated uncertainties. The ecological safety level was defined by RQ ≤ 1. Results indicated that both in water and sediment, fluoranthene and pyrene posed the highest risks, whereas acenaphthene and fluorene posed negligible risks. Naphthalene and phenanthrene did not pose risks to the ecological community in surface water but had relatively higher risks in sediment. The median RQs of combined risk in surface water and sediment were 0.934 and 2.42, and the probabilities of RQ > 1 were up to 0.473 and 0.599, respectively, which were much higher than the individual compound acting alone. The risk level in sediment was quite higher than in surface water probably owing to the non-equilibrium distribution between two phases, which suggested that local authorities should focus more on sediment quality management.

Evaluating nanoparticle breakthrough during drinking water treatment

BACKGROUND

Use of engineered nanoparticles (NPs) in consumer products is resulting in NPs in drinking water sources. Subsequent NP breakthrough into treated drinking water is a potential exposure route and human health threat.

OBJECTIVES

In this study we investigated the breakthrough of common NPs--silver (Ag), titanium dioxide (TiO2), and zinc oxide (ZnO)--into finished drinking water following conventional and advanced treatment.

METHODS

NPs were spiked into five experimental waters: groundwater, surface water, synthetic freshwater, synthetic freshwater containing natural organic matter, and tertiary wastewater effluent. Bench-scale coagulation/flocculation/sedimentation simulated conventional treatment, and microfiltration (MF) and ultrafiltration (UF) simulated advanced treatment. We monitored breakthrough of NPs into treated water by turbidity removal and inductively coupled plasma-mass spectrometry (ICP-MS).

RESULTS

Conventional treatment resulted in 2-20%, 3-8%, and 48-99% of Ag, TiO2, and ZnO NPs, respectively, or their dissolved ions remaining in finished water. Breakthrough following MF was 1-45% for Ag, 0-44% for TiO2, and 36-83% for ZnO. With UF, NP breakthrough was 0-2%, 0-4%, and 2-96% for Ag, TiO2, and ZnO, respectively. Variability was dependent on NP stability, with less breakthrough of aggregated NPs compared with stable NPs and dissolved NP ions.

CONCLUSIONS

Although a majority of aggregated or stable NPs were removed by simulated conventional and advanced treatment, NP metals were detectable in finished water. As environmental NP concentrations increase, we need to consider NPs as emerging drinking water contaminants and determine appropriate drinking water treatment processes to fully remove NPs in order to reduce their potential harmful health outcomes.

Health risks associated with heavy metals in the drinking water of Swat, northern Pakistan

The concentrations of heavy metals such as Cd, Cr, Cu, Mn, Ni, Pb and Zn were investigated in drinking water sources (surface and groundwater) collected from Swat valley, Khyber Pakhtunkhwa, Pakistan. The potential health risks of heavy metals to the local population and their possible source apportionment were also studied. Heavy metal concentrations were analysed using atomic absorption spectrometer and compared with permissible limits set by Pakistan Environmental Protection Agency and World Health Organization. The concentrations of Cd, Cr, Ni and Pb were higher than their respective permissible limits, while Cu, Mn and Zn concentrations were observed within their respective limits. Health risk indicators such as chronic daily intake (CDI) and health risk index (HRI) were calculated for adults and children separately. CDIs and HRIs of heavy metals were found in the order of Cr > Mn > Ni > Zn > Cd > Cu > Pb and Cd > Ni > Mn > Cr > Cu > Pb > Zn, respectively. HRIs of selected heavy metals in the drinking water were less than 1, indicating no health risk to the local people. Multivariate and univariate statistical analyses showed that geologic and anthropogenic activities were the possible sources of water contamination with heavy metals in the study area.

Signal transduction disturbance related to hepatocarcinogenesis in mouse by prolonged exposure to Nanjing drinking water

Toxicogenomic approaches were used to investigate the potential hepatocarcinogenic effects on mice by oral exposure to Nanjing drinking water (NJDW). Changes in the hepatic transcriptome of 3 weeks male mice (Mus musculus) were monitored and dissected after oral exposure to NJDW for 90 days. No preneoplastic and neoplastic lesions were observed in the hepatic tissue by the end of NJDW exposure. However, total of 746 genes were changed transcriptionally. Thirty-one percent of differentially expressed genes (DEGs) were associated with the functional categories of cell cycle regulation, adhesion, growth, apoptosis, and signal transduction, which are closely implicated in tumorigenesis and progression. Interrogation of Kyoto Encyclopedia of Genes and Genomes revealed that 43 DEGs were mapped to several crucial signaling pathways implicated in the pathogenesis of hepatocellular carcinoma (HCC). In signal transduction network constructed via Genes2Networks software, Egfr, Akt1, Atf2, Ctnnb1, Hras, Mapk1, Smad2, and Ccnd1 were hubs. Direct gene-disease relationships obtained from Comparative Toxicogenomics Database and scientific literatures revealed that the hubs have direct mechanism or biomarker relationships with hepatocellular preneoplastic lesions or hepatocarcinogenesis. Therefore, prolonged intake of NJDW without employing any indoor water treatment strategy might predispose mouse to HCC. Furthermore, Egfr, Akt1, Ctnnb1, Hras, Mapk1, Smad2, and Ccnd1 were identified as promising biomarkers of the potential combined hepatocarcinogenicity.

Spatial distribution and source apportionment of water pollution in different administrative zones of Wen-Rui-Tang (WRT) river watershed, China

Water quality degradation in river systems has caused great concerns all over the world. Identifying the spatial distribution and sources of water pollutants is the very first step for efficient water quality management. A set of water samples collected bimonthly at 12 monitoring sites in 2009 and 2010 were analyzed to determine the spatial distribution of critical parameters and to apportion the sources of pollutants in Wen-Rui-Tang (WRT) river watershed, near the East China Sea. The 12 monitoring sites were divided into three administrative zones of urban, suburban, and rural zones considering differences in land use and population density. Multivariate statistical methods [one-way analysis of variance, principal component analysis (PCA), and absolute principal component score-multiple linear regression (APCS-MLR) methods] were used to investigate the spatial distribution of water quality and to apportion the pollution sources. Results showed that most water quality parameters had no significant difference between the urban and suburban zones, whereas these two zones showed worse water quality than the rural zone. Based on PCA and APCS-MLR analysis, urban domestic sewage and commercial/service pollution, suburban domestic sewage along with fluorine point source pollution, and agricultural nonpoint source pollution with rural domestic sewage pollution were identified to the main pollution sources in urban, suburban, and rural zones, respectively. Understanding the water pollution characteristics of different administrative zones could put insights into effective water management policy-making especially in the area across various administrative zones.

Evaluating the spatial distribution of quantitative risk and hazard level of arsenic exposure in groundwater, case study of Qorveh County, Kurdistan Iran

Regional distribution of quantitative risk and hazard levels due to arsenic poisoning in some parts of Iran’s Kurdistan province is considered. To investigate the potential risk and hazard level regarding arsenic-contaminated drinking water and further carcinogenic and non-carcinogenic effects on villagers, thirteen wells in rural areas of Qorveh County were considered for evaluation of arsenic concentration in water. Sampling campaign was performed in August 2010 and arsenic concentration was measured via the Silver Diethyldithiocarbamate method. The highest and lowest arsenic concentration are reported in Guilaklu and Qezeljakand villages with 420 and 67 μg/L, respectively. None of thirteen water samples met the maximum contaminant level issued by USEPA and Institute of Standards and Industrial Research of Iran (10 ppb). The highest arsenic concentration and consequently risk and hazard levels belong to villages situated alongside the eastern frontiers of the county. Existence of volcanic activities within the upper Miocene and Pleistocene in this part of the study area may be addressed as the main geopogenic source of arsenic pollution. Quantitative risk values are varying from 1.49E-03 in Qezeljakand to 8.92E-03 in Guilaklu and may be interpreted as very high when compared by similar studies in Iran. Regarding non-carcinogenic effects, all thirteen water samples are considered hazardous while all calculated chronic daily intakes are greater than arsenic reference dose. Such drinking water source has the potential to impose adverse carcinogenic and non-carcinogenic effects on villagers. Accordingly, an urgent decision must be made to substitute the current drinking water source with a safer one.