Below are abstracts for published research studies from a variety of sources. Click on the article title to be taken to the complete article or to receive directions on how to purchase it.
Martin, JA, Edberg, SC, Clancy, JL and Hrudey, SE, Critical Reviews in Microbiology, November 25, 2013.
Accounts of drinking water-borne disease outbreaks have always captured the interest of the public, elected and health officials, and the media. During the twentieth century, the drinking water community and public health organizations have endeavored to craft regulations and guidelines on treatment and management practices that reduce risks from drinking water, specifically human pathogens. During this period there also evolved misunderstandings as to potential health risk associated with microorganisms that may be present in drinking waters. These misunderstanding or “myths” have led to confusion among the many stakeholders. The purpose of this article is to provide a scientific- and clinically-based discussion of these “myths” and recommendations for better ensuring the microbial safety of drinking water and valid public health decisions.
Edberg, SC, DWRF, September 2013.
Drinking water regulations are designed to protect the public health. In the United States, the Environmental Protection Agency (EPA) is tasked with developing and maintaining drinking water regulations for the 276,607,387 people served by the country’s 54,293 community water systems. The Food and Drug Administration (FDA) regulates bottled water as a food product. By federal law, the FDA’s regulations for bottled water must be at least as protective of public health as the EPA’s regulations for public water system drinking water. Despite many similarities in EPA and FDA regulations, consumer perception regarding the safety of drinking waters varies widely. This paper examines and compares the microbial health risks of tap water and bottled water, specifically examining differences in quality monitoring, regulatory standards violations, advisories, and distribution system conditions. It also includes comparison data on the number of waterborne illness outbreaks caused by both tap and bottled water. Based on a review of existing research, it is clear that as a consequence of the differences in regulations, distribution systems, operating (manufacturing) practices, and microbial standards of quality, public drinking water supplies present a substantially higher human risk than do bottled waters for illness due to waterborne organisms.
Allevi RP, Krometis LA, Hagedorn C, Benham B, Lawrence AH, Ling EJ, Ziegler PE, Journal of Water and Health, June 2013.
Over one million households rely on private water supplies (e.g. well, spring, cistern) in the Commonwealth of Virginia, USA. The present study tested 538 private wells and springs in 20 Virginia counties for total coliforms (TCs) and Escherichia coli along with a suite of chemical contaminants. A logistic regression analysis was used to investigate potential correlations between TC contamination and chemical parameters (e.g. NO3(-), turbidity), as well as homeowner-provided survey data describing system characteristics and perceived water quality. Of the 538 samples collected, 41% (n = 221) were positive for TCs and 10% (n = 53) for E. coli. Chemical parameters were not statistically predictive of microbial contamination. Well depth, water treatment, and farm location proximate to the water supply were factors in a regression model that predicted presence/absence of TCs with 74% accuracy. Microbial and chemical source tracking techniques (Bacteroides gene Bac32F and HF183 detection via polymerase chain reaction and optical brightener detection via fluorometry) identified four samples as likely contaminated with human wastewater.
Gerke TL, Little BJ, Luxton TP, Scheckel KG, and Maynard JB, Environmental Science and Technology, April 22, 2013.
The United States Environmental Protection Agency (US EPA) will require some U.S. drinking water distribution systems (DWDS) to monitor nonradioactive strontium (Sr2+) in drinking water in 2013. Iron corrosion products from four DWDS were examined to assess the potential for Sr2+ binding and release. Average Sr2+ concentrations in the outermost layer of the corrosion products ranged from 3 to 54 mg kg–1 and the Sr2+ drinking water concentrations were all ≤0.3 mg L–1. Micro-X-ray adsorption near edge structure spectroscopy and linear combination fitting determined that Sr2+ was principally associated with CaCO3. Sr2+ was also detected as a surface complex associated with α-FeOOH. Iron particulates deposited on a filter inside a home had an average Sr2+ concentration of 40.3 mg kg–1 and the associated drinking water at a tap was 210 μg L–1. The data suggest that elevated Sr2+ concentrations may be associated with iron corrosion products that, if disturbed, could increase Sr2+ concentrations above the 0.3 μg L–1 US EPA reporting threshold. Disassociation of very small particulates could result in drinking water Sr2+ concentrations that exceed the US EPA health reference limit (4.20 mg kg–1 body weight).
Triantafyllidou S, Nguyen CK, Zhang Y, Edwards MA, Environmental Monitoring and Assessment, February 2013.
Assessing the health risk from lead (Pb) in potable water requires accurate quantification of the Pb concentration. Under worst-case scenarios of highly contaminated water samples, representative of public health concerns, up to 71-98 % of the total Pb was not quantified if water samples were not mixed thoroughly after standard preservation (i.e., addition of 0.15 % (v/v) HNO(3)). Thorough mixing after standard preservation improved recovery in all samples, but 35-81 % of the total Pb was still un-quantified in some samples. Transfer of samples from one bottle to another also created high errors (40-100 % of the total Pb was un-quantified in transferred samples). Although the United States Environmental Protection Agency's standard protocol avoids most of these errors, certain methods considered EPA-equivalent allow these errors for regulatory compliance sampling. Moreover, routine monitoring for assessment of human Pb exposure in the USA has no standardized protocols for water sample handling and pre-treatment. Overall, while there is no reason to believe that sample handling and pre-treatment dramatically skew regulatory compliance with the US Pb action level, slight variations from one approved protocol to another may cause Pb-in-water health risks to be significantly underestimated, especially for unusual situations of "worst case" individual exposure to highly contaminated water.
Burroughs A, Rin D, FDLI Update, December 2012.
This article examines three recent cases brought under the controversial Park doctrine in search of clues to the doctrine's future. The responsible corporate officer (RCO) doctrine, also known as the Park doctrine, allows for criminal prosecution of individuals, typically high-ranking corporate executives of pharmaceutical companies, for violations of the Food, Drug and Cosmetic Act (FDCA), even absent any proof of the individual defendant's knowledge of or participation in the violation. It is relevant to drinking water because the Park law applies to bottled water, but not to tap water.
Collier SA, Stockman LJ, Hicks LA, Garrison LE, Zhou FJ, and Beach MJ, Epidemiology and Infection, November 2012;140(11):2003-13.
Despite US sanitation advancements, millions of waterborne disease cases occur annually, although the precise burden of disease is not well quantified. Estimating the direct healthcare cost of specific infections would be useful in prioritizing waterborne disease prevention activities. Hospitalization and outpatient visit costs per case and total US hospitalization costs for ten waterborne diseases were calculated using large healthcare claims and hospital discharge databases. The five primarily waterborne diseases in this analysis (giardiasis, cryptosporidiosis, Legionnaires' disease, otitis externa, and non-tuberculous mycobacterial infection) were responsible for over 40 000 hospitalizations at a cost of $970 million per year, including at least $430 million in hospitalization costs for Medicaid and Medicare patients. An additional 50 000 hospitalizations for campylobacteriosis, salmonellosis, shigellosis, haemolytic uraemic syndrome, and toxoplasmosis cost $860 million annually ($390 million in payments for Medicaid and Medicare patients), a portion of which can be assumed to be due to waterborne transmission.
Levine, RL, Journal of Environmental Health, November 2012.
Many public water systems in the U.S. are unsafe because the communities cannot afford to comply with the current 10 parts per billion (ppb) federal arsenic standard for drinking water. Communities unable to afford improvements remain vulnerable to adverse health effects associated with higher levels of arsenic exposure. Scientific and bipartisan political consensus exists that the arsenic standard should not be less stringent than 10 ppb, and new data suggest additional adverse health effects related to arsenic exposure through drinking water. Congress has failed to reauthorize the Drinking Water State Revolving Fund program to provide reliable funding to promote compliance and reduce the risk of adverse health effects. Congress's recent ad hoc appropriations do not allow long-term planning and ongoing monitoring and maintenance. Investing in water infrastructure will lower health care costs and create American jobs. Delaying necessary upgrades will only increase the costs of improvements over time.
Lambertini E, Borchardt M, Kieke BA, Spencer S, and Loge F, Environmental Science and Technology, July 27, 2012.
Acute gastrointestinal illness (AGI) resulting from pathogens directly entering the piping of drinking water distribution systems is insufficiently understood. Here, we estimate AGI incidence from virus intrusions into the distribution systems of 14 nondisinfecting, groundwater-source, community water systems. Water samples for virus quantification were collected monthly at wells and households during four 12-week periods in 2006–2007. Ultraviolet (UV) disinfection was installed on the communities’ wellheads during one study year; UV was absent the other year. UV was intended to eliminate virus contributions from the wells and without residual disinfectant present in these systems, any increase in virus concentration downstream at household taps represented virus contributions from the distribution system (Approach 1). During no-UV periods, distribution system viruses were estimated by the difference between well water and household tap virus concentrations (Approach 2). For both approaches, a Monte Carlo risk assessment framework was used to estimate AGI risk from distribution systems using study-specific exposure–response relationships. Depending on the exposure–response relationship selected, AGI risk from the distribution systems was 0.0180–0.0661 and 0.001–0.1047 episodes/person-year estimated by Approaches 1 and 2, respectively. These values represented 0.1–4.9% of AGI risk from all exposure routes, and 1.6–67.8% of risk related to drinking water exposure. Virus intrusions into nondisinfected drinking water distribution systems can contribute to sporadic AGI.
Sales-Ortells H, Medema G, Environmental Science and Technology, April 3, 2012.
A screening-level risk assessment of Q fever transmission through drinking water produced from groundwater in the vicinity of infected goat barnyards that employed aeration of the water was performed.
Kelly A. Reynolds, MSPH, Ph.D., Water Conditioning & Purification, March 2012.
Microbial threats to water quality continue to emerge; however, technologies for monitoring, treating and controlling emerging waterborne pathogens are also evolving. Understanding the range of factors that lead to the contamination of water are important for developing appropriate tools to manage human health risks.
Yasar Kemal Erdem, Furkan Acar, International Journal of Applied Science and Technology, 2012; Vol. 2 No. 1
Bisphenol-A is a widely used chemical in the structure of epoxy resins, polycarbonate packages, lacquer of metal food packages all over the world. Its weak estrogenic character and possible health effects are well known. For this reason the usage of the Bisphenol-A in food packages is limited and it’s daily intake by human is restrictly under control. The declaration of specific migration limit is 0.6 ppm, the tolerable daily intake is 0.05mg/kg body weight per day by EFSA and other authorities. The EFSA and others prevent the manufacturing and using of Bisphenol-A in baby bottles in 2010. In Turkey, the 70% of the population are living in 5 metropolitan cities and the drinking water consumption is mostly supplied by packaged drinking water industry. The household and bulk usage is covered by natural spring and natural mineral water packaged in 19 liters polycarbonate carboys. That’s why the possible migration of Bisphenol-A in drinking water packaged in polycarbonate carboys was decided to investigate. First of all, a screening test was carried out in the samples supplied by two main cities. And then 5 different trade mark packaged water samples was stored at 4, 25, and 35oC for 60 days and Bisphenol-A content was determined in given intervals. It is found that the BPA migration was detected at least 450 times lower than the specific migration limit of EFSA during 60 days storage at these conditions.
Reynolds KA, Mena KD, Gerba CP, Reviews of Environmental Contamination & Toxicology, 2008;192:117-58
Outbreaks of disease attributable to drinking water are not common in the U.S., but they do still occur and can lead to serious acute, chronic, or sometimes fatal health consequences, particularly in sensitive and immunocompromised populations. From 1971 to 2002, there were 764 documented waterborne outbreaks associated with drinking water, resulting in 575,457 cases of illness and 79 deaths (Blackburn et al. 2004; Calderon 2004); however, the true impact of disease is estimated to be much higher. If properly applied, current protocols in municipal water treatment are effective at eliminating pathogens from water. However, inadequate, interrupted, or intermittent treatment has repeatedly been associated with waterborne disease outbreaks. Contamination is not evenly distributed but rather affected by the number of pathogens in the source water, the age of the distribution system, the quality of the delivered water, and climatic events that can tax treatment plant operations. Private water supplies are not regulated by the USEPA and are generally not treated or monitored, although very few of the municipal systems involved in documented outbreaks exceeded the USEPA's total coliform standard in the preceding 12 mon (Craun et al. 2002). We provide here estimates of waterborne infection and illness risks in the U.S. based on the total number of water systems, source water type, and total populations exposed. Furthermore, we evaluated all possible illnesses associated with the microbial infection and not just gastroenteritis. Our results indicate that 10.7 M infections/yr and 5.4 M illnesses/yr occur in populations served by community groundwater systems; 2.2 M infections/yr and 1.1 M illnesses/yr occur in noncommunity groundwater systems; and 26.0 M infections/yr and 13.0 M illnesses/yr occur in municipal surface water systems. The total estimated number of waterborne illnesses/yr in the U.S. is therefore estimated to be 19.5 M/yr. Others have recently estimated waterborne illness rates of 12M cases/yr (Colford et al. 2006) and 16 M cases/yr (Messner et al. 2006), yet our estimate considers all health outcomes associated with exposure to pathogens in drinking water rather than only gastrointestinal illness. Drinking water outbreaks exemplify known breaches in municipal water treatment and distribution processes and the failure of regulatory requirements to ensure water that is free of human pathogens. Water purification technologies applied at the point-of-use (POU) can be effective for limiting the effects of source water contamination, treatment plant inadequacies, minor intrusions in the distribution system, or deliberate posttreatment acts (i.e., bioterrorism). Epidemiological studies are conflicting on the benefits of POU water treatment. One prospective intervention study found that consumers of reverse-osmosis (POU) filtered water had 20%-35% less gastrointestinal illnesses than those consuming regular tap water, with an excess of 14% of illness due to contaminants introduced in the distribution system (Payment 1991, 1997). Two other studies using randomized, blinded, controlled trials determined that the risks were equal among groups supplied with POU-treated water compared to untreated tap water (Hellard et al. 2001; Colford et al. 2003). For immunocompromised populations, POU water treatment devices are recommended by the CDC and USEPA as one treatment option for reducing risks of Cryptosporidium and other types of infectious agents transmitted by drinking water. Other populations, including those experiencing "normal" life stages such as pregnancy, or those very young or very old, might also benefit from the utilization of additional water treatment options beyond the current multibarrier approach of municipal water treatment.
T. J. Luben,J. R. Nuckols, B. S. Mosley, C. Hobbs,J. S. Reif, Occupational and Environmental Medicine, June 2008
The use of chlorine for water disinfection results in the formation of numerous contaminants called disinfection by-products (DBPs), which may be associated with birth defects, including urinary tract defects. MethodsWe used Arkansas birth records (1998-2002) to conduct a population-based case-control study investigating the relationship between hypospadias and two classes of DBPs, trihalomethanes (THM) and haloacetic acids (HAA). We utilised monitoring data, spline regression and geographical information systems (GIS) to link daily concentrations of these DBPs from 263 water utilities to 320 cases and 614 controls. We calculated ORs for hypospadias and exposure to DBPs between 6 and 16 weeks' gestation, and conducted subset analyses for exposure from ingestion, and metrics incorporating consumption, showering and bathing. Results: We found no increase in risk when women in the highest tertiles of exposure were compared to those in the lowest for any DBP. When ingestion alone was used to assess exposure among a subset of 40 cases and 243 controls, the intermediate tertiles of exposure to total THM and the five most common HAA had ORs of 2.11 (95% CI 0.89 to 5.00) and 2.45 (95% CI 1.06 to 5.67), respectively, compared to women with no exposure. When exposure to total THM from consumption, showering and bathing exposures was evaluated, we found an OR of 1.96 (95% CI 0.65 to 6.42) for the highest tertile of exposure and weak evidence of a dose-response relationship. Conclusions: Our results provide little evidence for a positive relationship between DBP exposure during gestation and an increased risk of hypospadias but emphasize the necessity of including individual-level data when assessing exposure to DBPs.
Yuan-Yuan Zhao, Jessica M. Boyd, Matthew Woodbeck, Robert C. Andrews, Feng Qin, Steve E. Hrudey, Xing-Fang Li, Environmental Science & Technology, May 2008
Formation of nine N-nitrosamines has been investigated when seven different source waters representing various qualities were each treated with eleven bench-scale disinfection processes, without addition of nitrosamine precursors. These disinfection treatments included chlorine (OCl-) chloramine (NH2Cl), chlorine dioxide (ClO2), ozone (O3), ultraviolet (UV), advanced oxidation processes (AOP), and combinations. The total organic carbon (TOC) of the seven source waters ranged from 2 to 24 mg L-1. The disinfected water samples and the untreated source waters were analyzed for nine nitrosamines using a solid phase extraction and liquid chromatography-tandem mass spectrometry method. Prior to any treatment, N-nitrosodimethylamine (NDMA) was detected ranging from 0 to 53 ng L-1 in six of the seven source waters, and its concentrations increased in the disinfected water samples (0 - 118 ng L-1). N-nitrosodiethylamine (NDEA), N-nitrosomorpholine (NMor), and N-nitrosodiphenylamine (NDPhA) were also identified in some of the disinfected water samples. NDPhA (0.2- 0.6 ng L-1) was formed after disinfection with OCl-, NH2Cl, O3, and MPUV/OCl-. NMEA was produced with OCl- and MPUV/OCl-, and NMor formation was associated with O3. In addition, UV treatment alone degraded NDMA; however, UV/OCl- and AOP/OCl- treatments produced higher amounts of NDMA compared to UV and AOP alone, respectively. These results suggest that UV degradation or AOP oxidation treatment may provide a source of NDMA precursors. This study demonstrates that environmental concentrations and mixtures of unknown nitrosamine precursors in source waters can form NDMA and other nitrosamines.
Carsten K. Schmidt, Heinz-J- Brauch, Environmental Science & Technology, April 2008
Application and microbial degradation of the fungicide tolylfluanide gives rise to a new decomposition product named N,N-dimethylsulfamide (DMS). In Germany, DMS was found in groundwaters and surface waters with typical concentrations in the range of 100-1000 ng/L and 50-90 ng/L, respectively. Laboratory-scale and field investigations concerning its fate during drinking water treatment showed that DMS cannot be removed via riverbank filtration, activated carbon filtration, flocculation, and oxidation or disinfection procedures based on hydrogen peroxide, potassium permanganate, chlorine dioxide, or UV irradiation. Even nanofiltration does not provide a sufficient removal efficiency. During ozonation about 30-50% of DMS are converted to the carcinogenic N-nitrosodimethylamine (NDMA). The NDMA being formed is biodegradable and can at least partially be removed by subsequent biologically active drinking water treatment steps including sand or activated carbon filtration. Disinfection with hypochlorous acid converts DMS to so far unknown degradation products but not to NDMA or 1,1-dimethylhydrazine (UDMH).
Kimberley Chisholm, Angus Cook, Carol Bower, Philip Weinstein, Environmental Health Perspective, April 2008
By international standards, water supplies in Perth, Western Australia contain high trihalomethane (THM) levels, particularly the brominated forms. Geographical variability in these levels provided an opportunity to examine cross-city spatial relationships between THM exposure and rates of birth defects. The objective is to examine birth defect rates by exposure to THMs with a highly brominated fraction in metropolitan locations in Perth, Western Australia. Water samples were collected from 47 separate locations. Samples were analyzed for total and individual THM concentrations in ?g/L, including separation into brominated forms.
Maclehose RF, Savitz DA, Herring AH, Hartmann KE, Singer PC, Weinberg HS, Epidemiology, March 2008
Laboratory evidence suggests tap water disinfection by-products (DBPs) could have an effect very early in pregnancy, typically before clinical detectability. Undetected early losses would be expected to increase the reported number of cycles to clinical pregnancy. METHODS:: We investigated the association between specific DBPs (trihalomethanes, haloacetic acids, brominated-trihalomethanes, brominated-haloacetic acids, total organic halides, and bromodichloromethane) and time to pregnancy among women who enrolled in a study of drinking water and reproductive outcomes. We quantified exposure to DBPs through concentrations in tap water, quantity ingested through drinking, quantity inhaled or absorbed while showering or bathing, and total integrated exposure. The effect of DBPs on time to pregnancy was estimated using a discrete time hazard model. RESULTS:: Overall, we found no evidence of an increased time to pregnancy among women who were exposed to higher levels of DBPs. A modestly decreased time to pregnancy (ie, increased fecundability) was seen among those exposed to the highest level of ingested DBPs, but not for tap water concentration, the amount absorbed while showering or bathing, or the integrated exposure. CONCLUSIONS: Our findings extend those of a recently published study suggesting a lack of association between DBPs and pregnancy loss.
Nasrul Hamidin, Qiming Jimmy Yu, Des W. Connell, Water Research, March 2008
The presence of chlorinated disinfection by-products (DBPs) in drinking water is a public health issue, due to their possible adverse health effects on humans. To gauge the risk of chlorinated DBPs on human health, a risk assessment of chloroform (trichloromethane (TCM)), bromodichloromethane (BDCM), dibromochloromethane (DBCM), bromoform (tribromomethane (TBM)), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in drinking water was carried out using probabilistic techniques. Literature data on exposure concentrations from more than 15 different countries and adverse health effects on test animals as well as human epidemiological studies were used. The risk assessment showed no overlap between the highest human exposure dose (EXP(D)) and the lowest human equivalent dose (HED) from animal test data, for TCM, BDCM, DBCM, TBM, DCAA and TCAA. All the HED values were approximately 10(4)-10(5) times higher than the 95th percentiles of EXP(D). However, from the human epidemiology data, there was a positive overlap between the highest EXP(D) and the lifetime average daily doses (LADD(H)) for TCM, BDCM, DCAA and TCAA. This suggests that there are possible adverse health risks such as a small increased incidence of cancers in males and developmental effects on infants. However, the epidemiological data comprised several risk factors and exposure classification levels which may affect the overall results.
Bing-Fang Hwang, Jouni Jaakkola, How-Ran Guo, Environmental Health, 2008
Recent findings suggest that exposure to disinfection by-products may increase the risk of birth defects. Previous studies have focused mainly on birth defects in general or groups of defects. The objective of the present study was to assess the effect of water disinfection by-products on the risk of most common specific birth defects. We conducted a population-based cross-sectional study of 396,049 Taiwanese births in 2001-2003 using information from the Birth Registry and Waterworks Registry. We compared the risk of eleven most common specific defects in four disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs) representing high (TTHMs 20+ ug/L), medium (TTHMs 10-19 ug/L), low exposure (TTHMs 5-9 ug/L), and 0-4 ug/L as the reference category. In addition, we conducted a meta-analysis of the results from the present and previous studies focusing on the same birth defects.
Center for Disease Control, June 2007
In this study, the Center for Disease Control (CDC) considers persons with weakened immune systems and makes a number of recommendations regarding drinking water, including the following. Because you cannot be sure your tap water is safe, you may wish to avoid tap water, including water or ice from a refrigerator ice-maker, which is made from tap water. Always check with the local health department and water utility to see if they have issued any special notices for people with HIV about tap water. You may also wish to boil or filter your water, or to drink bottled water. Processed carbonated (bubbly) drinks in cans or bottles should be safe, but drinks made at a fountain might not be because they are made with tap water. If you choose to boil or filter your water or to drink only bottled water, do this all the time, not just at home.
, Environmental Health Perspectives, June 2007
A groundwater-associated outbreak affected approximately 1,450 residents and visitors of South Bass Island, Ohio, between July and September 2004. To examine the microbiological quality of groundwater wells located on South Bass Island, we sampled 16 wells that provide potable water to public water systems 15–21 September 2004. We tested groundwater wells for fecal indicators, enteric viruses and bacteria, and protozoa (Cryptosporidium and Giardia). The hydrodynamics of Lake Erie were examined to explore the possible surface water–groundwater interactions. All wells were positive for both total coliform and Escherichia coli. Seven wells tested positive for enterococci and Arcobacter (an emerging bacterial pathogen), and F+-specific coliphage was present in four wells. Three wells were positive for all three bacterial indicators, coliphages, and Arcobacter; adenovirus DNA was recovered from two of these wells. We found a cluster of the most contaminated wells at the southeast side of the island. Conclusions: Massive groundwater contamination on the island was likely caused by transport of microbiological contaminants from wastewater treatment facilities and septic tanks to the lake and the subsurface, after extreme precipitation events in May–July 2004. This likely raised the water table, saturated the subsurface, and along with very strong Lake Erie currents on 24 July, forced a surge in water levels and rapid surface water–groundwater interchange throughout the island. Landsat images showed massive influx of organic material and turbidity surrounding the island before the peak of the outbreak. These combinations of factors and information can be used to examine vulnerabilities in other coastal systems. Both wastewater and drinking water issues are now being addressed by the Ohio Environmental Protection Agency and the Ohio Department of Health.
Kelly A. Reynolds, Water Conditioning & Purification, February 2007
There is little published research regarding pathogen occurrence, growth and survival specifically in premise plumbing. Although limited data is available regarding HPC bacteria, these bacteria generally are not a human health risk and offer little information relative to the associative prevalence of harmful microbial populations. Pipe materials appear to be a factor in bacterial colonization and re-growth in the distribution system. Plastic faucets have been shown to harbor higher numbers of specific bacteria (i.e., coliforms) compared to metal; however, iron pipes appear to support a higher diversity of bacteria compared to PVC surfaces.3 We do not know the extent of the public health risks associated with microbes and their ecology in distribution systems or whether or not diversity and selectivity of specific bacterial groups is preferred. In fact, several studies have shown that HPC bacteria are antagonistic to pathogens when they are introduced to the established microflora of premise plumbing.
Information is not currently available regarding the changes that occur in microbial populations in the premise plumbing compared to the distribution system. While it is documented that 51.4 percent (4/7) of the waterborne outbreaks in community water systems in the US from 2001-2002 were related to problems in the distribution system, no information is available regarding exposures to harmful organisms in premise plumbing. This is surprising considering the increased potential for pathogen survival, growth and introduction. If waterborne disease outbreaks occur from problems in premise plumbing, they are unlikely to be detected or reported due to the small population affected (i.e., a single household). Overall, these data gaps mean that very little is known about the quality of water that consumers are actually drinking from the tap. In order to evaluate health risks and mitigation approaches, much more research is needed to determine the types, numbers, growth and disease potentials of the microbial communities at the point of consumption.
David M. DeMarini, Fritz H. Frimmel, Thomas Glauner, Tamara Grummt, Susan D. Richardson, Christian Zweiner, Environmental Science & Technology, January 2007
Disinfection is mandatory for swimming pools: public pools are usually disinfected by gaseous chlorine or sodium hypochlorite and cartridge filters; home pools typically use stabilized chlorine. These methods produce a variety of disinfection byproducts (DBPs), such as trihalomethanes (THMs), which are regulated carcinogenic DBPs in drinking water that have been detected in the blood and breath of swimmers and of nonswimmers at indoor pools. Also produced are halogenated acetic acids (HAAs) and haloketones, which irritate the eyes, skin, and mucous membranes; trichloramine, which is linked with swimming-pool-associated asthma; and halogenated derivatives of UV sun screens, some of which show endocrine effects. DBPs may be reduced by engineering and behavioral means, such as applying new oxidation and filtration methods, reducing bromide and iodide in the source water, increasing air circulation in indoor pools, and assuring the cleanliness of swimmers. The positive health effects gained by swimming can be increased by reducing the potential adverse health risks.
Michael Messner, Susan Shaw, Stig Regli, Ken Rotert, Valerie Blank and Jeff Soller, Journal of Water and Health, 2006;04.suppl2:201-40
In this paper, the US Environmental Protection Agency (EPA) presents an approach and a national estimate of drinking water related endemic acute gastrointestinal illness (AGI) that uses information from epidemiologic studies. There have been a limited number of epidemiologic studies that have measured waterborne disease occurrence in the United States. For this analysis, we assume that certain unknown incidence of AGI in each public drinking water system is due to drinking water and that a statistical distribution of the different incidence rates for the population served by each system can be estimated to inform a mean national estimate of AGI illness due to drinking water. Data from public water systems suggest that the incidence rate of AGI due to drinking water may vary by several orders of magnitude. In addition, data from epidemiologic studies show AGI incidence due to drinking water ranging from essentially none (or less than the study detection level) to a rate of 0.26 cases per person-year. Considering these two perspectives collectively, and associated uncertainties, EPA has developed an analytical approach and model for generating a national estimate of annual AGI illness due to drinking water. EPA developed a national estimate of waterborne disease to address, in part, the 1996 Safe Drinking Water Act Amendments. The national estimate uses best available science, but also recognizes gaps in the data to support some of the model assumptions and uncertainties in the estimate. Based on the model presented, EPA estimates a mean incidence of AGI attributable to drinking water of 0.06 cases per year (with a 95% credible interval of 0.02–0.12). The mean estimate represents approximately 8.5% of cases of AGI illness due to all causes among the population served by community water systems. The estimated incidence translates to 16.4 million cases/year among the same population. The estimate illustrates the potential usefulness and challenges of the approach, and provides a focus for discussions of data needs and future study designs. Areas of major uncertainty that currently limit the usefulness of the approach are discussed in the context of the estimate analysis.
Kelly A. Reynolds, Water Conditioning & Purification, July 2006
As water treatment professionals, maybe you've been alerted to news stories suggesting a connection between tap water consumption and bladder cancer, but are these headlines true or just media hype? Although the most recently reported association of tap water consumption with bladder cancer is indeed based on numerous epidemiological studies with an international scope, all scientific research must be carefully evaluated; not just in terms of the data found, but also for the information possibly missed. The study that has everyone talking again about tap water consumption and its relationship to bladder cancer was published in the International Journal of Cancer (April 2006). Looking at data from six epidemiological studies, conducted in five countries worldwide (Canada, Finland, France, Italy and two in the United States), a significant association was found between tap water consumption and bladder cancer among men. The risk increased with consumption of greater volumes, suggesting that carcinogenic chemicals in tap water were responsible for the increased risk. While the information presented appears to be sound, it is important to understand the limitations of the study approach so that the data can be appropriately analyzed with respect to public health significance.
Despite a gender bias and inconsistent reports in the historical literature, this study seems to have sturdy legs to stand on or to at least justify continued research. As mentioned earlier, epidemiology is not a very sensitive science and is complicated by unknown confounders. In addition, this study provides no evidence as to what specific factors related to tap water are causing an increase in cancer, where other drinking water sources (i.e., bottled water) show no association. Water is clearly a heterogeneous mix of contaminants, with vast geographical and temporal fluctuations. Little is known about the combined effects of multiple contaminants found in drinking water, thus a study of single contaminants and their association with cancer risks would not provide a complete picture of overall exposures.
U.S. Geological Survey, June 2006
When volatile organic compounds (VOCs) are detected in samples from drinking-water supply wells, it is important to understand what these results may mean to human health. As a first step toward understanding VOC occurrence in the context of human health, a screening-level assessment was conducted by comparing VOC concentrations to human-health benchmarks. One sample from each of 3,497 domestic and public wells was analyzed for 55 VOCs; samples were collected prior to treatment or blending. At least one VOC was detected in 623 well samples (about 18 percent of all well samples) at a threshold of 0.2 part per billion. Eight of the 55 VOCs had concentrations greater than human-health benchmarks in 45 well samples (about 1 percent of all well samples); these concentrations may be of potential human-health concern if the water were to be ingested without treatment for many years. VOC concentrations were less than human-health benchmarks in most well samples with VOC detections, indicating that adverse effects are unlikely to occur, even if water with such concentrations were to be ingested over a lifetime. Seventeen VOCs may warrant further investigation because their concentrations were greater than, or approached, human-health benchmarks.
Richard J. Bull and Joseph A. Cotruvo, Toxicology, April 2006
Bromate is produced when ozone is used to treat waters that contain trace amounts of bromide ion. It may also be a contaminant of hypochlorite solutions. Both ozone and hypochlorite are extensively used to disinfect drinking water, a process that is credited with reducing the incidence of waterborne infections diseases around the world. In studies on experimental animals, bromate has been consistently demonstrated to induce cancer, although there is evidence of substantial species differences in sensitivity (rat > mouse > hamster). There are no data to indicate bromate is carcinogenic in humans. An issue that is critical to the continued use of ozone as a disinfectant for drinking water in bromide-containing waters depends heavily on whether current predictions of carcinogenic risk based on carcinogenic responses in male rats treated with bromate are accurate at the much lower exposure levels of humans.
Oscar Quinones, Shane A. Snyder, Joseph A. Cotruvo, Jeffrey W. Fisher, Toxicology, April 2006
Bromate is a regulated disinfection byproduct primarily associated with the ozonation of water containing bromide, but also is a byproduct of hypochlorite used to disinfect water. To study the pharmacokinetics of bromate, it is necessary to develop a robust and sensitive analytical method for the identification and quantitation of bromate in blood.
Jason D. Keith, Gilbert E. Pacey, Joseph A. Cotruvo, Gilbert Gordon, Toxicology, Febuary 2006
This study was designed to identify and quantify the effects of reducing agents on the rate of bromate ion reduction in real and synthetic gastric juice. A comparison of real and synthetic gastric juice containing H+, CL-, cysteine, glutathione, and hydrogen sulfide showed that the component most responsible for the considerable decrease of the concentration of bromate ion in the stomach is hydrogen sulfide.
Michael Messner, Susan Shaw, Stig Regli, Ken Rotert, Valerie Blank, Jeff Soller, Journal of Water and Health, 2006
In this paper, the US Environmental Protection Agency (EPA) presents an approach and a national estimate of drinking water related endemic acute gastrointestinal illness (AGI) that uses information from epidemiologic studies. There have been a limited number of epidemiologic studies that have measured waterborne disease occurrence in the United States. For this analysis, we assume that certain unknown incidence of AGI in each public drinking water system is due to drinking water and that a statistical distribution of the different incidence rates for the population served by each system can be estimated to inform a mean national estimate of AGI illness due to drinking water. Data from public water systems suggest that the incidence rate of AGI due to drinking water may vary by several orders of magnitude. In addition, data from epidemiologic studies show AGI incidence due to drinking water ranging from essentially none (or less than the study detection level) to a rate of 0.26 cases per person-year. Considering these two perspectives collectively, and associated uncertainties, EPA has developed an analytical approach and model for generating a national estimate of annual AGI illness due to drinking water. EPA developed a national estimate of waterborne disease to address, in part, the 1996 Safe Drinking Water Act Amendments. The national estimate uses best available science, but also recognizes gaps in the data to support some of the model assumptions and uncertainties in the estimate. Based on the model presented, EPA estimates a mean incidence of AGI attributable to drinking water of 0.06 cases per year (with a 95% credible interval of 0.02-0.12). The mean estimate represents approximately 8.5% of cases of AGI illness due to all causes among the population served by community water systems. The estimated incidence translates to 16.4 million cases a year among the same population. The estimate illustrates the potential usefulness and challenges of the approach, and provides a focus for discussions of data needs and future study designs. Areas of major uncertainty that currently limit the usefulness of the approach are discussed in the context of the estimate analysis.
Jay A. Switzer, Vishnu V. Rajasekharan, Sansanee Boonsalee, Elizabeth A. Kulp, Eric W. Bohannan, Environmental Science & Technology, 2006
Many water districts have recently shifted from free chlorine (in the form of HOCl/OCl-) to monochloramine (NH2Cl) as a disinfectant for drinking water to lower the concentration of chlorinated hydrocarbon byproducts in the water. There is concern that the use of NH2Cl disinfectant may lead to higher Pb levels in drinking water. In this study, the electrochemical quartz crystal microbalance is used to compare the effects of these two disinfectants on the dissolution of Pb films. A 0.5 µm thick Pb film nearly completely dissolves in a NH2Cl solution, but it is passivated in a HOCl/OCl- solution. X-ray diffraction analysis shows that the NH2Cl oxidizes Pb to Pb(II) species such as Pb3(OH)2(CO3)2, whereas the stronger oxidant, HOCl/OCl-, oxidizes Pb to Pb(IV) as an insoluble PbO2 conversion coating. Although NH2Cl may produce less halogenated organic byproducts than HOCl/OCl- when used as a disinfectant, it may lead to increased Pb levels in drinking water.
Kelly A. Reynolds, Water Conditioning & Purification, September 2005
Not all bottled waters are the same and surveys reporting a variety of contaminants can be randomly found around the globe. Despite criticisms, the safety record of bottled water is exemplary and it is potentially a life-saving product for those who do not have access to adequately treated water supplies, including supplies contaminated during disaster events. Generally, bottled water offers a safe, convenient alternative to tap water and many consumers report that they prefer the taste of bottled water. Consumers are advised to be informed about the source water quality and treatment level of bottled water consumed, especially when traveling abroad. Immuno-compromised individuals who are at increased risk of microbial disease are cautioned against tap water consumption and should also be wary of bottled waters that do not employ U.S. EPA approved methods.
M.J. Allen, S.C. Edberg and D.J. Reasoner, International Journal of Food Microbiology, April 2002
This paper reviews the relevant literature on Heterotrophic Plate Count (HPC) bacteria in drinking water, the lack of clinical evidence that elevated populations or specific genera within the HPC flora pose an increased health risk to any segment of the population, and the appropriate uses of HPC data as a tool to monitor drinking water quality changes following treatment.
S.G. Wadhwa, G.H. Khaled and S.C. Edberg, Critical Reviews in Microbiology, 2002
Drinking water does not support the growth of pathogens. Food possesses a manifold greater risk than drinking water, and government agencies should take this into account when writing regulations. Virtually all food sources contain hundreds of thousands more bacteria than drinking water.
P. Mota, S.C. Edberg, Critical Reviews in Microbiology, 2000
A critical analysis the human health risk associated with waterborne exposure to two relatively newly recognized protozoan agents: Cyclospora and Microsporidia, so that an approach to developing appropriate water testing and purification guidelines can be facilitated. The goal is to identify gaps in our current understanding to assist the development of appropriate and reasonable water quality regulations.
S.C. Edberg, S. Kops, C. Kontnick and M. Escargaza, Journal of Applied Microbiology, 1997
An issue affecting all drinking water, but in particular importance to bottled water, is the possible adverse health effects of naturally occurring microbes, collectively called heterotrophic plate count (HPC). This paper discusses a study conducted in order to isolate HPC from tap water and bottled water products. The HPC were isolated on blood agar and then subjected to a large battery of tests to determine if they possessed characteristics associated with human infection, known as virulence factors.
Naturally occurring HPC bacteria demonstrated low invasiveness and cytotoxicity with more than 95 of isolates showing equivalency to broth supernatant. When showing either invasiveness or cytotoxicity, only a small number of cells from the culture were positive.
S.C. Edberg, J.B. Robertson, Critical Reviews in Microbiology, 1997
One of the multiple barriers that can be claimed for human health protection is source water sequestration. In particular, some groundwaters may be so sequestered and not under the influence of surface water directly so as to preclude microbial intrusion. A practicing hydrogeologist (Mr. John Robertson, Hydro Geologic] and practicing medical microbiologist (Dr. Stephen Edberg, Yale University) collaborated to develop hydrogeological parameters that would ensure the integrity and sequestration of the source water.
S.C. Edberg, C. Hardalo, Critical Reviews in Microbiology, 1997
Pseudomonas aeruginosa is a bacterium that is naturally found in many types of drinking water. It is a violation of European regulations to have Pseudomonas aeruginosa present in a 250 ml sample of bottled water. However, no such regulation exists in the United States. Apparently, the Pseudomonas aeruginosa regulation in Europe originated as a quality control issue and not as a health effects issue.
During the last decade, a number of papers have appeared that have indicated that Pseudomonas aeruginosa from drinking water is a health threat. However, it is not considered a health threat by those in the clinical microbiology or infectious diseases communities. Therefore, an assessment of health risk to humans from Pseudomonas aeruginosa from drinking water was conducted. A practicing infectious disease physician (Dr. Catherine Hardalo, Yale University) and a medical microbiologist (Dr. Stephen Edberg, Yale University) collaborated to perform the health risk analysis of Pseudomonas aeruginosa from drinking water.