Assessing Children's Exposures and Risks to Drinking Water Contaminants: A Manganese Case Study

Background: Compared to adults, children maybe more highly exposed to toxic substances in drinking water because they consume more water per unit of body weight. The U.S. Environmental Protection Agency (USEPA) has developed new guidance for selecting age groups and age-specific exposure factors for assessing children's exposures and risks to environmental contaminants. Research Aim: To demonstrate the application and importance of applying age-specific drinking water intake rates, health reference values, and exposure scenarios when assessing drinking water exposures because these approaches illustrate the potential for greater potential for adverse health effects among children. Methods: manganese, an essential nutrient and neurotoxicant, was selected as a case study and chemical of potential concern for children's health. A screening-level risk assessment was performed using age-specific drinking water intake rates and manganese concentrations from U.S. public drinking water systems. Results: When age-specific drinking water intake rates are used to calculate dose, formula-fed infants receive the highest dose of manganese from drinking water compared to all other age groups. Estimated hazard quotients suggest adverse health effects are possible. Use of USEPA's standardized childhood age groups and childhood exposure factors significantly improves the understanding of childhood exposure and risks.     

Risk assessment of adenoviruses detected in treated drinking water and recreational water

AIMS: Human adenoviruses (HAds) have previously been detected in sewage and polluted river and dam water, as well as treated drinking water. The 51 serotypes of HAds cause a wide range of infections with clinical manifestations associated with the gastrointestinal, respiratory and urinary tracts, and the eyes. Water may play a meaningful role in the transmission of many of these HAd serotypes, specifically the enteric HAds which are transmitted via the faecal-oral route. The presence of these viruses in water used for drinking and recreational purposes is considered to constitute a potential health risk. In this study, the risk of infection by the group of HAds previously detected over a period of 1 year in selected drinking water supplies, as well as river and dam water used for recreational purposes, was assessed. METHODS AND RESULTS: Adenoviruses were previously detected in nine of 204 (4.41%) samples of two drinking water supplies (A and B) treated and disinfected according to international specifications, in four of 51 (7.8%) samples of river water and nine of 51 (17.7%) samples of dam water. Application of these previously published results in an exponential risk assessment model indicated an annual risk of infection of 1.01 x 10(-1) and 1.7 x 10(-1) for drinking water supplies A and B, respectively, assuming a daily consumption of 2 l day(-1). The daily risk of infection constituted by HAds in the river water was calculated as 1.71 x 10(-4), and in the dam water as 3.12 x 10(-5), assuming a consumption of 30 ml of water per day. CONCLUSIONS: The risk of infection exceeded the tolerable risk of one infection per 10 000 consumers per year proposed for drinking water. However, the results for river and dam water used for recreational purposes were within the tolerable risk of one infection per 1000 bathers per day proposed for environmental waters used for recreational purposes. SIGNIFICANCE AND IMPACT OF THE STUDY: The study showed that the risk of HAd infection calculated for the drinking water supplies and the recreational water may overestimate the actual risk of infection, as conservative values were assumed for some of the variables. For a more accurate assessment of the potential risk of infection research should at least include a thorough investigation of the water consumption of individuals in South Africa, and the efficiency of recovery of the glass wool adsorption-elution method.     

A Human Health Risk Assessment of Pharmaceuticals in the Aquatic Environment

Analyses were conducted on four pharmaceutical compounds, representing different therapeutic classes, to evaluate the presence and potential adverse human health effects of trace levels of these substances in aqueous environmental media. Acetylsalicylic acid, clofibrate, cyclophosphamide, and indomethacin have been detected in aqueous environmental media including sewage treatment plant effluent, surface water, drinking water, and groundwater. An extensive literature search and chemical-specific risk assessments were performed to assess the potential human health significance of each compound's individual presence in environmental media. Safe water quality limits were estimated for each pharmaceutical by following the USEPA Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health and were compared to the concentrations found in the environment. The calculation of the provisional ambient water quality criteria involved estimation of human exposure to contaminated water, including intake via bioaccumulation in fish, and calculation of cancer risk and non-cancer hazard indices. Parameters detailing the toxicological and pharmacological nature, exposure assessment, and environmental fate and transport of each pharmaceutical were also considered. The overall conclusion was that based on available data, no appreciable risk to humans exists, as the detected concentrations of each of these pharmaceutical compounds found in aqueous media were far below the derived safe limits     

Oral Bioaccessibility and Leaching: Tests for Soil Risk Assessment

A set of test methods for estimating the risk for human health (oral bioaccessibility tests) and groundwater (leaching tests) was applied to contaminated soils from three sites with different sources of contamination. The bioaccessible soil concentrations of the contaminants cadmium, lead, nickel, benzo(a)pyrene and dibenz(a,h)anthracene were considerably lower than the total concentrations. The leached concentrations of the polycyclic aromatic hydrocarbons, cadmium and nickel were below the EU drinking water and Danish groundwater criteria, whereas the leached lead concentrations were below the drinking water criteria but above the groundwater criteria. Based upon the test results, a risk assessment of the soils with respect to human health (oral exposure) and groundwater was established that reflected a reduced availability and mobility of PAH and heavy metals in the soils.     

The use of environmental media evaluation guides for screening environmental contamination

In conducting health assessments at hazardous‐waste sites, ATSDR staff must identify environmental chemical contaminants that pose a potential public health hazard. To assist health assessors in this effort, ATSDR has developed environmental media evaluation guides (EMEGs). EMEGs have been developed for water, soil, and air. The EMEG values are expressed as a range to account for the range in exposures in different segments of the population. The use of EMEGs provides health assessors with a consistent strategy for selecting environmental contaminants to be further evaluated in the health assessment process.     

Arsenic and heavy metals health risk assessment through drinking water consumption in the Peshawar District,Pakistan

This study aimed to assess the drinking water quality and human potential health risk in Peshawar, which is the most populous district of Khyber Pakhtunkhwa Province, Pakistan. Water was randomly collected throughout Peshawar District (urban = 45 samples and rural = 29 samples). These samples were analyzed for heavy metal (As, Cd, Co, Cu, Cr, Hg, Ni, Pb, and Zn) concentrations using the atomic absorption spectrometer (Perkin Elmer, AAS-PEA-700). Heavy metal concentrations in drinking water revealed the highest pollution index (PI) values—17.80, 11.92, 7.50, and 5.70 for the Pb, Cr, Cd, and Ni, respectively. The contaminations of Cd and Pb were significantly higher (p < .05) than their maximum allowable limits set by the World Health Organization. Heavy metal contaminations in drinking water were evaluated for health risk assessment: the chronic risk or hazard quotient (HQ) and cancer risk. Results revealed that HQ values were >1 for the Cd and Pb, suggesting that the exposed human beings could be at chronic risk. Therefore, serious measures such as drinking water treatments and contamination controlling policies are needed to avoid the hazardous effects of toxic heavy metals.     

Potential for biofilm development in drinking water distribution systems

Regrowth of micro-organisms in drinking water distribution systems is caused by the utilisation of biodegradable compounds which are either present in treated water or originate from materials in contact with drinking water. In the Netherlands most drinking water is distributed without disinfectant residual and regrowth is limited by achieving biostable drinking water. A combination of methods is used to assess the biostability of drinking water. These methods are: (1) determination of the concentration of easily assimilable organic carbon (AOC); and (2) assessment of the biofilm formation rate (BFR). Assimilated organic carbon concentrations in drinking water in the Netherlands range from a few μg C/l in slow sand filtrates and in ground water supplies to values of ～ 50 μg C/l in supplies using ozonation in water treatment. Biofilm formation rate values were found to range from < 1 pg ATP/cm(2)/d in supplies using anaerobic ground water as the source. Increase of heterotrophic plate counts is limited at AOC values below 10 μg C/l. At BFR values below 10 pg ATP/cm(2)/d the risk of exceeding the guideline value for aeromonads (90 percentile < 200 c.f.u./100 ml) is less than 20%. Calculations based on the decrease of the AOC concentration observed in distributions systems confirm that very low concentrations of AOC can cause considerable biofilm formation on the pipe wall. The methods for assessing the biostability of drinking water combine with the assessment of the Biofilm Formation Potential of materials in contact with drinking water, thus providing a framework, the Unified Biofilm Approach, for evaluating the biostability of drinking water and materials.     

Environmental Risks at Finnish Shooting Ranges—A Case Study

We studied three Finnish shooting ranges in order to define the extent of the risks associated with elevated environmental concentrations of metals and PAHs. A scoring system revealed that lead, arsenic, and antimony were the most critical contaminants. On Site 3, the concentration of lead in groundwater exceeded the drinking water standard indicating evident health risks. For the remaining two sites we calculated Acceptable Daily Doses (ADD) based on the Reasonable Maximum Exposure (RME) approach and compared them with safe exposure levels. We also used a pharmacokinetic model to determine blood lead levels (PbBs). Risks to biota were assessed using ecological benchmarks and exposure and accumulation models. Prediction of leaching was based on laboratory tests and a distribution model. The health risk assessment for lead resulted in the maximum hazard quotient (HQ) of 1.2 whereas the HQs of As and Sb remained less than 1. Some exposure scenarios produced PbB estimates exceeding 10 μ g dl^?1 but based on the uncertainty analysis we expect the health risks to remain insignificant. However, leaching of contaminants presents a risk to groundwater quality. At site 1 the ecotoxicity-based HQs demonstrate high risks to soil biota, small mammals, terrestrial plants and aquatic organisms.     

Irrigated agriculture and freshwater wetlands: A struggle for coexistence in the western United States

This paper is a review of the major environmental problems associated with irrigated agriculture in the western United States. Freshwater wetlands are being contaminated by subsurface agricultural irrigation drainage in many locations. Historic freshwater inflows have been diverted for agricultural use, and remaining freshwater supplies are not sufficient to maintain these important natural areas once they are degraded by irrigation drainage. Migratory birds have been poisoned by drainwater contaminants on at least six national wildlife refuges; waterfowl populations are threatened in the Pacific and Central flyways. Revised water allocation policies and regulatory actions are probably necessary to correct existing damage and prevent future problems. The benefits of maintaining healthy wetlands should be used as a rationale for negotiating increases in freshwater supplies. Cost analyses that show the importance of wetlands in dollar values are critical to the success of these negotiations. The next few years will provide unique opportunities for wetland managers to use cost analyses to make changes in water allocation policies. Federally subsidized water has supported and expanded agriculture at the expense of native wetlands for over 100 years in the western United States. This trend must be reversed if these wetlands and their fish and wildlife populations are to survive.     

Using Ecological Risk Assessment Principles in a Source Water Protection Assessment

It has become increasingly common to apply ecological risk assessment (ERA) principles to watershed and regional scale environmental management. This article describes the application of watershed ERA principles to the development of a source water protection assessment and a strategic watershed management plan. The primary focus was on the protection of drinking water quality, a concern typically addressed by human health risk assessors. The approach emphasizes adaptations to the problem formulation phase of ERA (defining assessment endpoints, developing conceptual models and an analysis plan) suitable for watershed management planning in a multi-objective, multi-stressor context. Physical, chemical, and biological attributes were selected for primary drinking water quality assessment endpoints, and coupled with additional assessment endpoints relevant to other environmental and social management objectives. Conceptual models helped the planning team to better understand and communicate the multiple natural and human stressors in the watershed and the causal pathways by which they affected drinking water. The article provides an example of the types of adaptations that can make ERA principles suitable for watershed management related to human health goals, and illustrates the efficiency of integrating health and ecological assessments.     

An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

The practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems. This was accomplished by coupling the system dynamics-based decision support system CARO-PLUS to the aquatic ecosystem model AQUATOX using an analytical volatilization model for the stream. The model was applied to a case study where a trichloroethylene (TCE)-contaminated groundwater plume is discharging to a stream. The TCE source will not be depleted for many decades; however, measured and predicted TCE concentrations in surface water were found to be below human health risk management targets. Volatilization rapidly attenuates TCE concentrations in surface water. Thus, only a 30-m stream reach fails to meet surface water quality criteria. An ecological risk assessment found that the TCE contamination did not impact the stream ecosystem. Uncertainty assessment revealed hydraulic conductivity to be the most important site-specific parameter. These results indicate that contaminant plumes with μg L^?1 concentrations of TCE entering surface water systems may not pose a significant risk.     

Contaminant Trends in Freshwater Fish from the Laurentian Great Lakes: A 20-Year Analysis

Although dietary concerns of Laurentian Great Lakes (GL) fish focus on the risk from persistent bioaccumulative toxicant (PBT) contaminants, fish are also an important source of nutrients beneficial to human health such as polyunsaturated fatty acids (e.g., eicosapentanoic acid and docosahexanoic acid). This study presents PBT trend data from the GL tribal fisheries over the past 20 years. PBT contaminants (282 analytes) from fillet portions of lake trout and whitefish were analyzed for trending patterns from 1992 to 2011 and are reported on five of the ATSDR/USEPA Great Lakes biomonitoring legacy contaminants (Hg, ΣDDE, ΣDDT, HCB, mirex, and ΣPCBs), two of the optional biomonitoring PBTs (toxaphene and Σdioxins/furans) and PCB 153 as a specific congener marker. Similar to other recent reports our data indicate that most PBT contaminant concentrations in the GL biota have decreased, which may indicate progress in reducing environmental emissions. Our research confirms that all contaminants demonstrate significant declines except Hg and toxaphene. Both of those remained constant after correcting for known independent factors of age, lipid, and size. These results are potentially encouraging and may provide useful data for the long distance and perhaps global influences of PBTs on the safety of fish consumption.     

Annual cancer risks from chemicals in North Carolina community water systems

Motivated partly by concerns about cancer, the U.S. Congress in 1986 amended the Safe Drinking Water Act (SDWA) by requiring that community water systems monitor 81 chemicals and remove those detected at concentrations above health-based standards. No prior research has used the resulting 30 years of monitoring data to analyze cancer risks from chemicals in US drinking water. To fill this gap, this paper uses chemical monitoring data from North Carolina's (NC's) 2,120 community water systems along with a risk assessment approach commonly applied in global burden of disease studies to quantify cancer risks of regulated chemicals in drinking water. The results indicate that 0.30% of NC cancer deaths are attributable to regulated drinking water contaminants and that the average annual individual risk is 7.2 × 10^?6. More than 99% of this risk arises from disinfection by-products, with the remaining risk mostly attributable to arsenic and alpha particle radiation. In no water system does the combined risk from chemicals other than disinfection by-products, arsenic, or alpha particles exceed 10^?4. The results suggest that regulated chemicals pose very low cancer risks and that risks from chemicals other than disinfection by-products, arsenic, and alpha particles are negligible in NC community water systems.     

Hydrogeochemical evolution and risk assessment of human health in a riverbank filtration site,northeastern China

Intensive agriculture and industrial activities have resulted in contamination in rivers and groundwater quality, which threatens human health. In this study, we used comprehensive physiochemical indicators to assess the quality of groundwater used for drinking and irrigation in addition to the potential risks to local residents in a riverbank filtration site. Human health risks through drinking water intake and dermal contact were also estimated. Moreover, we analyzed the spatial distribution regularities of health risk values in a riverbank filtration site. The assessment results revealed that NH₄–N, NO₂–N, F^?, Mn, and As are main contaminants affecting groundwater quality and that 62% of the total samples is suitable for a variety of purposes. All groundwater in the study area is suitable for irrigation based on the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), Na percentage (%Na), and U.S. Salinity Laboratory (USSL) and Wilcox diagrams. The health risk assessment suggests that residents in the study area are at high health risk, and women and children face higher risk than men in both non-carcinogenic and carcinogenic risks. The spatial distribution regularities of health risk values suggest that the human health risk value of each groundwater sample is different in the study area and has certain regularity. Therefore, effective measurements must be taken to address the groundwater contamination and to reduce the human health risks.     

A Probabilistic Assessment of Household Exposures to MTBE from Drinking Water

The oxygenate methyl tertiary butyl ether (MTBE) has been added to reformulated gasoline in the U.S. to meet national ambient air quality standards. Although MTBE has provided significant health benefits in terms of reduced criteria and toxic air pollutants, detections of MTBE in some groundwater and drinking water sources have raised concerns about potential environmental contamination and human exposures. In this paper, we examine the frequency and concentration of MTBE detections in drinking water sources in California from 1995 to 1999, and provide a preliminary analysis of the distribution of household exposures to MTBE from water-related activities. Using published data on the toxicity and possible cancer hazard posed by MTBE, we estimate the likely cancer and non-cancer risks for the general population in California from past and potential future MTBE exposures. More highly exposed subgroups were also addressed. Our findings indicate that less than 2% of all sampled drinking water sources in California had detectable levels of MTBE in 1999, with average MTBE drinking water concentrations ranging from 0.09 to 4.9?ppb for this year. Both the detection rate for MTBE and average MTBE concentrations have remained relatively stable since 1995, despite increased sampling of drinking water sources in California. The probabilistic exposure analysis suggests that drinking water exposures to MTBE are unlikely to pose a significant health risk for the general population or more highly exposed individuals in California.     

Non-Carcinogenic Risk Assessment of Heavy Metals and Fluoride in Some Water Wells in the Al-Baha Region,Saudi Arabia

On a global scale, pathogenic contamination of drinking water poses the most significant health risk to humans. However, significant risks to human health may also result from exposure to nonpathogenic, toxic contaminants that are often ubiquitous in waters. The purpose of this study is to determine the levels of heavy metal and fluoride contaminants in water wells used in the Al-Baha region, Saudi Arabia, to evaluate if the levels of metals will have non-carcinogenic effects. Samples were collected from private wells in the area and were analyzed for chemical contamination using approved methods of collection and analysis. Chromium, manganese, zinc, iron, and fluoride were detected in all samples, and were selected for toxicological evaluation. Exposure through ingestion and dermal contact were the scenarios proposed in this study. Chronic daily intakes (CDIs) were estimated for both routes and then compared with health guideline values. The non-cancer risk estimations show that manganese, chromium, and zinc individually have oral Hazard Quotient (HQ) values less than a value of one. Iron and fluoride were found to have oral HQ values greater than 1 in some samples. Also, on considering the additive effect of the contaminants we found that some samples have Hazard Index (HI) values greater than 1, which indicates that there is a concern for chronic non-cancer adverse health effects in case of oral and dermal routes of exposure to water from these wells.     

Risk Assessment Applications Beyond Baseline Risks and Clean-Up Goals

Historically, the phrase “Risk Assessment” brought to mind a thick Superfund-type baseline risk assessment or clean-up goal derivation document filled with pages of tables with endless seemingly unrelated algorithms and numbers. Over the last decade, the principles of risk and exposure assessment have gained wide-reaching acceptance and are increasingly utilized to help solve other environmental impact, occupational health, or risk mitigation design problems. The typical objective of the classic risk assessment is the evaluation of current or future risks from exposure to contaminated media within the framework of a regulatory waste management or remediation program. Risk-based techniques are increasingly being used on a voluntary basis (i.e., outside of the standard regulatory arena) to demonstrate the presence, absence, or extent of environmental or health-related concerns in specific exposure circumstances. Likewise, a risk or exposure evaluation may be useful in determining the need for, or the legitimacy of, a public health advisory, alone or in conjunction with remedial or mitigative actions. Finally, risk-based techniques often find their way into the courtroom. Three case studies are presented in which riskbased solutions were employed to assist in resolving environmental or health-related issues: (1) a reversal of a fish consumption advisory; (2) an evaluation of arsenic in soil on and adjacent to a school facility; and (3) a challenge to a case of alleged methyl bromide exposure in a litigation context. In each case, the use of risk assessment principles was employed beyond the classic baseline risk assessment to address an applied problem of toxicological significance.     

Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s–1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure.     

黑龙江省农村饮用水水质健康风险评价

本文以黑龙江省农村饮用水为研究对象,调研分析了该地区农村饮用水水质状况和水质问题,筛查出三种可能造成人体健康风险的典型污染物:砷,氟化物,硝酸盐。在此基础上,选用了USEPA推荐的水质风险健康评价模型对三种污染进行了健康风险评价,评价结果表明砷的健康风险值大于最大可接受限值10-(6a-1),存在较大人体健康风险,氟化物和亚硝酸盐人体健康风险较小。此外,根据水质健康风险评价结果,对保障黑龙江省农村饮用水实质安全提出了初步解决措施。