A Risk Assessment Approach for Policy Evaluation: New Jersey Case Studies

Monitoring environmental policy progress often focuses on contaminant concentrations while policy goals address health. To bridge this gap, we developed policy evaluation case studies applying risk assessment methods to explore population health risks of chemical exposures before and after policy implementation. Beginning in the 1970s the New Jersey Department of Environmental Protection provided some of the United States' first data on contaminants including trichloroethylene in drinking water and polychlorinated biphenyls (PCBs) in fish. These data provide a unique opportunity to evaluate environmental policies. The 1979 PCB manufacturing ban succeeded in reducing exposure and risk, but the persistence of these compounds in local fish requires continued state and local consumption advisories. The positive impact of drinking water standards for trichloroethylene was reflected in declining detection in public water supplies from the late 1970s to 2005, although maximum concentrations in a small percentage of supplies remain above standards. Our case studies show success and progress, and the need for multiple policies in combination when conditions warrant. Tracking specific policies and contaminants using risk assessment methods can be a valuable tool for policy evaluation and can foster population-based environmental health research. Pollution prevention policies are warranted for chemicals that persist in the environment.     

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.     

Probabilistic Estimates of Lifetime Daily Doses from Consumption of Drinking Water Containing Trace Levels of N,N-diethyl-meta-toluamide (DEET), Triclosan,or Acetaminophen and the Associated Risk to Human Health

Risk assessments were conducted for N,N-diethyl-meta-toluamide (DEET), triclosan, and acetaminophen to evaluate the risk from exposure to trace levels of these chemicals through drinking water consumption. We estimated exposure to these chemicals through drinking water consumption by generating distributions for key exposure parameters using Monte Carlo analysis. Body weight and water consumption was modeled using data from the U.S. Environmental Protection Agency (USEPA) Exposure Factor Handbook. Water concentrations were derived from reported concentrations in streams. Dose-response was evaluated through extensive literature searches for toxicology data for each chemical. Acceptable daily intakes (ADIs) were then derived from the available toxicology data. The exposure distributions were compared to the ADIs to evaluate the potential risk to the population from drinking water exposure. ADIs of 0.100, 0.153, and 0.05 mg/kg-day were derived for DEET, acetaminophen and triclosan, respectively. The maximum estimated exposures (0.082, 0.834, and 0.193 μ g/kg/day for DEET, acetaminophen, and triclosan, respectively) were at least 100-fold lower than the corresponding ADIs. Based on these assessments, we conclude that there is minimal risk to human health from exposure to these chemicals at the reported concentrations in U.S. streams.     

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.     

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.     

In vitro modeling of dental water line contamination and decontamination

The contamination of dental unit water lines (DUWL) is an emerging concern in dentistry. The aim of this study was to use an in vitro DUWL to model microbial contamination and evaluate the decontamination efficacy of tetraacetylethylenediamine (TAED) solutions. A DUWL biofilm model used to simulate clinical conditions was used to generate a range of biofilms in DUWL. Three distinct biofilms were generated: (1) biofilm from water, (2) biofilm from a mix of water + contaminating human commensal bacteria, (3) biofilm from water with contaminating oral bacteria added after biofilm formed. The contaminating oral species used were Streptococcus oralis, Enterococcus faecalis and Staphylococcus aureus. Decontamination by simple water flushing or flushing with TAED was evaluated (2, 5 and 10 min intervals). The DUWL tubes were split and samples were plated onto a range of media, incubated and bacteria enumerated. Water flushing did not reduce the number of microorganisms detected. Bacteria were not detected from any of the TAED sampling points for any of the biofilm types tested. Interestingly, if contamination was introduced to new DUWL along with the waterborne species a biofilm was formed containing only the waterborne species. If however, an existing biofilm was present before the introduction of "contaminating" bacteria then these could be detected in the biofilm. This implies that if the DUWL are new or satisfactorily cleaned on a regular basis then the associated cross-contamination aspects are reduced. In conclusion, TAED provides effective control for DUWL biofilms.     

Oxidative DNA damage from potassium bromate exposure in Long-Evans rats is not enhanced by a mixture of drinking water disinfection by-products

Public drinking water treated with chemical disinfectants contains a complex mixture of disinfection by-products (DBPs) for which the relative toxicity of the mixtures needs to be characterized to accurately assess risk. Potassium bromate (KBrO(3)) is a by-product from ozonation of high-bromide surface water for production of drinking water and is a rodent carcinogen that produces thyroid, mesothelial, and renal tumors. The proposed mechanism of KBrO(3) renal carcinogenesis involves the formation of 8-oxoguanine (8-oxoG), a promutagenic base lesion in DNA typically removed through base excision repair (BER). In this study, male Long-Evans rats were exposed via drinking water to carcinogenic concentrations of KBrO(3) (0.4 g/L), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (0.07 g/L), chloroform (1.8 g/L), bromodichloromethane (0.7 g/L), or a mixture of all these chemicals at the same concentrations for 3 weeks. Half of one kidney was processed for microscopic examination, and the remaining kidney was frozen for isolation of genomic DNA. Levels of 8-oxoG were measured using HPLC with electrochemical detection in DNA samples incubated with formamidopyrimidine-DNA glycosylase. Aldehydic lesions (e.g. abasic sites) in DNA samples were quantitated using an aldehyde-reactive probe slot-blot assay. Treatment with KBrO(3) produced a measurable increase of 8-oxoG in the kidney, and this effect was greater than that produced by treatment with the DBP mixture. No other single chemical treatment caused measurable increases of 8-oxoG. The mixture effect on the amount of 8-oxoG observed in this study suggests an interaction between chemicals that reduced the generation of oxidative DNA damage. No increases in abasic sites were observed with treatment, but a decrease was apparent in the rats treated with the DBP mixture. These data are consistent with previous studies where chronic exposure to this chemical mixture in drinking water resulted in a less than additive carcinogenic response in Tsc2 mutant Long-Evans rats.     

Evaluation of chronic toxicities from sediments before and after ecological project in Meiliang Bay, Lake Taihu, using cell bioassays

An ecological project for water purification was conducted in Meiliang Bay, Lake Taihu, which supplies one-third of the drinking water for Wuxi City, China. Sediment dredging was employed. The floating-leaf and floating macrophytes were planted, combined with wave-attenuating, algal bloom blocking to improve the water quality. At the same time, large amounts of fish net were placed in the experimental zone, to which massive periphytes adhere. To evaluate the effectiveness of remediation, many studies were based on chemical analysis or acute toxicity test. In this study, chronic toxicities before and after the ecological project in Meiliang Bay, Lake Taihu, China, were evaluated based on a battery of in vitro bioassays, including EROD bioassay, recombined yeast assay, as well as umu test for detection of Ah-receptor (AhR) agonists, estrogenic chemicals and genotoxic chemicals, respectively. Before remediation, AhR effect, estrogenic effect and indirect genotoxicity were all detected in sediments of Meiliang Bay, Taihu Lake. After amelioration, levels of AhR agonists decreased by 42.3–80.7%, estrogenic chemicals decreased by 71.6–93.9% and indirect genotoxic chemicals decreased by 23.2–75.0%. Results showed that the ecological project effectively removed the chronic toxicants from the sediments.     

Characterization of microbial communities and composition in constructed dairy wetland wastewater effluent

Constructed wetlands have been recognized as a removal treatment option for high concentrations of contaminants in agricultural waste before land application. The goal of this study was to characterize microbial composition in two constructed wetlands designed to remove contaminants from dairy washwater. Water samples were collected weekly for 11 months from two wetlands to determine the efficiency of the treatment system in removal of chemical contaminants and total and fecal coliforms. The reduction by the treatment was greatest for biological oxygen demand, suspended solids, chemical oxygen demand, nitrate, and coliforms. There was only moderate removal of total nitrogen and phosphorus. Changes in the total bacterial community and ammonia-oxidizing bacterial composition were examined by using denaturing gradient gel electrophoresis (DGGE) and sequencing of PCR-amplified fragments of the gene carrying the alpha subunit of the ammonia monooxygenase gene (amoA) recovered from soil samples and DGGE bands. DGGE analysis of wetlands and manure samples revealed that the total bacterial community composition was dominated by bacteria from phylogenetic clusters related to Bacillus, Clostridium, Mycoplasma, Eubacterium, and Proteobacteria originally retrieved from the gastrointestinal tracts of mammals. The population of ammonia-oxidizing bacteria showed a higher percentage of Nitrosospira-like sequences from the wetland samples, while a higher percentage of Nitrosomonas-like sequences from manure, feces, raw washwater, and facultative pond was found. These results show that the wetland system is a natural process dependent upon the development of healthy microbial communities for optimal wastewater treatment.     

DGGE分析东江流域农村饮用水源中微生物多样性及其与环境因子相关性

为评价东江流域农村饮用水源中微生物多样性及其与环境因子的相关性, 分别采集了集中式供水井、塘坝型水井、猪场附近水井、普通村落水井、水库水5种水样, 进行基因组总DNA的提取和主要理化指标的测定, 运用DGGE技术分析各水样总DNA的PCR产物。UPGMA聚类分析DGGE指纹图谱结果表明, 相同类型水样的微生物群落结构相似性较高, 聚集到一个分支上; 典型相关性分析(CCA)结果表明, 水体中总磷(TP)和总氮(TN)的浓度与微生物群落结构的关联度最高, 即磷和氮两种生命过程的基本元素对微生物群落影响最大; 序列分析表明农村饮用水源中微生物群落结构丰富, 包含了螺旋体门(Spirochaetes)、蓝藻门(Cyanobacteria)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)5个门的细菌, 且每类水样拥有各自的优势菌。     

Effect of point-of-use, activated carbon filters on the bacteriological quality of rural groundwater supplies.

The water quality of 24 rural, domestic groundwater supplies treated with point-of-use, powdered activated carbon (PAC) filters was monitored to determine how such treatment might impact the bacteriological quality of private, residential drinking water supplies. Heterotrophic-plate-count (HPC) and total coliform analyses were performed on raw, PAC-treated, and overnight or stagnant (first-draw) PAC-treated water samples. Densities of HPC bacteria were elevated by 0.86 and 0.20 orders of magnitude for spring and well water systems, respectively, in PAC-treated effluents following overnight stagnation compared with levels in untreated treated effluents. Densities of HPC bacteria in PAC-treated effluents were significantly reduced (P < 0.01) below influent levels, however, after the point-of-use device was flushed for 2 min. While PAC significantly reduced the number of coliforms in product waters (P < 0.01), these indicator organisms were still detected in some effluents. Seasonal variations were evident in microbial counts from spring but not well water systems. It appears that aside from periods following stagnant-water use, such as overnight, PAC treatment does not compromise the bacteriological quality of drinking water obtained from underground sources.     

Desorption of Nitroaromatic Compounds From Explosive-contaminated Soil by Washing

The soil contaminated by explosive production wastewater was treated by washing using water as solvent. The effect of contact time and temperature, water/soil ratio and washing steps on desorption efficiency was investigated. Six kinetic models—parabolic diffusion model, zero-order equation, pseudo-first-order equation, pseudo-second-order equation, power function equation and Elovich equation—were used to study the desorption kinetics of nitroaromatic compounds from contaminated soil to water. The eluent of contaminated soil before and after washing was characterized by UV–vis analysis. The results showed that the removal rate was fast at the initial stage and then slowed down after 60 min. The desorption of contaminants from soil to water is endothermic. Washing with small quantities of water in high frequency is preferred when water volume is limited. The pseudo-second-order model can be used to describe the desorption process. Soil washing can remove most of the contaminants from the contaminated soil.     

Stressful effects of chemical toxins at low concentrations

Effects of three chemical compounds: ammonia, diethyl ether, and acetic acid, known as common environmental contaminants in technogenic accidents, were investigated in vivo and in vitro in low concentrations. When added in cultivation media, each of the chemicals has affected peritoneal macrophages and spleen lymphocytes isolated from male NMRI mice and led to a rise in the production of several cytokines, particularly the tumor necrosis factor-α and interferon-γ, as well as the expression of the inducible form of heat shock proteins (HSP72 and HSP90-α) and in the activation of signal cascades NF-κB and SAPK/JNK. The increase of the nitric oxide (NO) production in macrophages has been observed only when ammonia was added in cultivation media. Also, low concentrations of all compounds investigated led to the activation of the expression of receptor protein TLR4. When mice were exposed to airborne toxic contaminants in a hermetically sealed experimental chamber, an increase in the concentrations of cytokines, heat shock proteins, and signal proteins in immune cells was also observed in response to low concentrations of all chemicals investigated. Similarly to in vitro experiments, the NO production was augmented only in the presence of the airborne ammonia. The results indicate the environmental hazard of chemical contaminants even in rather low concentrations, which nevertheless lead to the stress response.     

The microbiological quality of drinking water sold on the streets in Kumasi,Ghana

AIM: The aim of this study was to assess the microbiological quality of Ghanaian bottled and plastic-bagged drinking water sold on the streets of Metropolitan Kumasi, Ghana. METHODS AND RESULTS: Eight bottled, 88 factory-filled plastic sachet and 40 hand-filled hand-tied polythene-bagged drinking waters were examined for the presence of heterotrophic bacteria total viable counts (TVCs), indicators of faecal contamination (total coliforms, faecal coliforms and enterococci) and for lead, manganese and iron. Heterotrophic bacteria were found in all three types of water with TVCs per millilitre ranging from 1 to 460 for bottled water, 2-6.33 x 10(5) for factory-bagged sachet water and 2.33 x 10(3)-7.33 x 10(12) for hand-filled hand-tied bagged water. None of the microbial indicators of faecal contamination were detected in bottled water, whereas 4.5% of the factory-bagged sachets contained total coliforms and 2.3% faecal coliforms, and 42.5% of the hand-filled hand-tied bags contained total coliforms, 22.5% faecal coliforms and 5% enterococci. Iron was found in all three types of drinking water but at concentrations well within the WHO recommendations. Lead and manganese were not detected. CONCLUSION: Ghanaian bottled water is of good microbiological quality but some factory-bagged sachet and hand-filled hand-tied polythene-bagged drinking water are of doubtful quality. SIGNIFICANCE AND IMPACT OF THE STUDY: Factory-bagged sachets and hand-filled hand-tied bags of drinking water sold in Ghana should be monitored for microbiological contamination, with the aim of raising standards in the industry and re-assuring the public.     

Changes in the structure and function of microbial communities in drinking water treatment bioreactors upon addition of phosphorus

Phosphorus was added as a nutrient to bench-scale and pilot-scale biologically active carbon (BAC) reactors operated for perchlorate and nitrate removal from contaminated groundwater. The two bioreactors responded similarly to phosphorus addition in terms of microbial community function (i.e., reactor performance), while drastically different responses in microbial community structure were detected. Improvement in reactor performance with respect to perchlorate and nitrate removal started within a few days after phosphorus addition for both reactors. Microbial community structures were evaluated using molecular techniques targeting 16S rRNA genes. Clone library results showed that the relative abundance of perchlorate-reducing bacteria (PRB) Dechloromonas and Azospira in the bench-scale reactor increased from 15.2% and 0.6% to 54.2% and 11.7% after phosphorus addition, respectively. Real-time quantitative PCR (qPCR) experiments revealed that these increases started within a few days after phosphorus addition. In contrast, after phosphorus addition, the relative abundance of Dechloromonas in the pilot-scale reactor decreased from 7.1 to 0.6%, while Zoogloea increased from 17.9 to 52.0%. The results of this study demonstrated that similar operating conditions for bench-scale and pilot-scale reactors resulted in similar contaminant removal performances, despite dramatically different responses from microbial communities. These findings suggest that it is important to evaluate the microbial community compositions inside bioreactors used for drinking water treatment, as they determine the microbial composition in the effluent and impact downstream treatment requirements for drinking water production. This information could be particularly relevant to drinking water safety, if pathogens or disinfectant-resistant bacteria are detected in the bioreactors.     

Microbial load of drinking water reservoir tributaries during extreme rainfall and runoff

Hygienic and microbiological examinations of watercourses are usually not carried out during heavy rainfall and runoff events. After rainfall or snowmelt, there are often massive increases in turbidity in flooding creeks in mountain ranges, which are frequently interpreted as an indication of microbial contamination. The aim of this study was to quantify the microbial loads of watercourses during such runoff events and to compare these loads with loads occurring during regular conditions. In a 14-month monitoring period we investigated the microbial loads of three tributaries of different drinking water reservoirs. A total of 99 water samples were taken under different runoff conditions and analyzed to determine physical, chemical, bacterial, and parasitic parameters. Thirty-two water samples were considered event samples during nine measuring series. The criteria for events, based on duration and intensity of precipitation, water depth gauge measurements, and dynamics, had been fixed before the investigation for each creek individually. Of the physical and chemical parameters examined, only the turbidity, pH, and nitrate values differed clearly from the values obtained for regular samples. Most of the bacteriological parameters investigated (colony, Escherichia coli, coliform, fecal streptococcal, and Clostridium perfringens counts) increased considerably during extreme runoff events. If relevant sources of parasitic contamination occurred in catchment areas, the concentrations of Giardia and Cryptosporidium rose significantly during events. The results show that substantial shares of the total microbial loads in watercourses and in drinking water reservoirs result from rainfall and extreme runoff events. Consequently, regular samples are considered inadequate for representing the microbial contamination of watercourse systems. The procedures for raw water surveillance in the context of multiple-barrier protection and risk assessment ought to include sampling during extreme runoff situations.     

Microbial Load of Drinking Water Reservoir Tributaries during Extreme Rainfall and Runoff

Hygienic and microbiological examinations of watercourses are usually not carried out during heavy rainfall and runoff events. After rainfall or snowmelt, there are often massive increases in turbidity in flooding creeks in mountain ranges, which are frequently interpreted as an indication of microbial contamination. The aim of this study was to quantify the microbial loads of watercourses during such runoff events and to compare these loads with loads occurring during regular conditions. In a 14-month monitoring period we investigated the microbial loads of three tributaries of different drinking water reservoirs. A total of 99 water samples were taken under different runoff conditions and analyzed to determine physical, chemical, bacterial, and parasitic parameters. Thirty-two water samples were considered event samples during nine measuring series. The criteria for events, based on duration and intensity of precipitation, water depth gauge measurements, and dynamics, had been fixed before the investigation for each creek individually. Of the physical and chemical parameters examined, only the turbidity, pH, and nitrate values differed clearly from the values obtained for regular samples. Most of the bacteriological parameters investigated (colony, Escherichia coli, coliform, fecal streptococcal, and Clostridium perfringens counts) increased considerably during extreme runoff events. If relevant sources of parasitic contamination occurred in catchment areas, the concentrations of Giardia and Cryptosporidium rose significantly during events. The results show that substantial shares of the total microbial loads in watercourses and in drinking water reservoirs result from rainfall and extreme runoff events. Consequently, regular samples are considered inadequate for representing the microbial contamination of watercourse systems. The procedures for raw water surveillance in the context of multiple-barrier protection and risk assessment ought to include sampling during extreme runoff situations.     

Chemical-based fecal source tracking methods: current status and guidelines for evaluation

Fecal source tracking is a rapidly evolving field for which there have been a number of method evaluation studies, workshops, review articles and a book that synthesize information about method efficacy. Chemicals that are specific to human wastewater offer several potential advantages over biologically based methods, but have received less scrutiny. More than 35 chemical analytes have been found to consistently occur in human waste streams and here we review these potential human-origin indicators in context of seven evaluation criteria. Some chemical methods offer advantages over microbial methods: they are generally faster to prepare and analyze, more source-specific because they are not confounded by regrowth in the environment, and some may be more geographically and temporally stable. However, they often require specialized equipment and are usually more expensive regarding sample preparation and analysis. Additionally, most chemicals that are specific to human waste-streams occur at concentrations low enough to be diluted below detection limits once the waste-stream enters the ambient environment. These two factors will likely result in chemical measures being used more often as cross-validation supplements or initial screening approaches, rather than replacements for microbial measures. Cross-validation supplements include several chemicals that are highly specific to human sources and can be important contributors when certainties about human sources are critical, such as in drinking water applications. At least one set of chemicals, fecal sterols and stanols, may have potential for identification of other sources in addition to humans. Of all the chemicals examined to date, optical brighteners (OBs) in detergents have shown considerable promise, especially for screening purposes. Optical brighteners are not as sensitive as most microbial assessments, but can be measured with a hand-held fluorometer, providing near real-time and relatively inexpensive tracking of signals in the field, if the human fecal source contains an OB concentration large enough to produce a measurable signal.