Chlorinated Surface Water Research Articles

Stormwater discharge: An overlooked source of disinfection byproduct precursors

Discharge from the stormwater system is as an important pathway for contaminant transport, impacting the quantity and characteristics of dissolved organic matter (DOM) in surface water, and thus the formation of disinfection byproducts (DBPs) during downstream drinking water disinfection. In this study, DOM in stormwater pipes was characterized by size-exclusion chromatography, and the formation of 27 DBPs and halogen-specific total organic halogen (TOX) following chlorination was investigated. Overall, DOM in stormwater pipes was characterized by low molecular weight compounds and microbial-derived organics. Total DBP concentrations in chlorinated stormwaters were ∼1–15 times higher than in chlorinated surface waters. DBPs formed in stormwaters were dominated by trihalomethanes and haloacetic acids. Moreover, the DBP-associated toxicity of chlorinated stormwaters was ∼1–38 times higher than in chlorinated surface waters, and mainly due to the presence of large amount of haloacetaldehydes and haloacetonitriles. Sampling during a rainfall event suggested that stormwater discharge significantly increased DBP precursors in the surface water. The high formation and estimated toxicity of DBPs in stormwater discharge indicates this is an overlooked source of DBP precursors, posing a threat to the aquatic environment and potentially drinking water quality.

Prevalence and Trends of Drinking Water Disinfection Byproducts-Related Cancers in Addis Ababa, Ethiopia

Background:Disinfection byproducts (DBPs) from chlorinated drinking water have been linked to an increased risk of cancer in the bladder, stomach, colon, and rectum. No studies showed the independent trends and prevalence of these cancers in Ethiopia. Therefore, this study aimed to determine the prevalence and trends of disinfection byproducts-related cancers in Addis Ababa, Ethiopia.Methods:Data were collected from the Addis Ababa Cancer Registry. Spatial data sets were produced and classified into households receiving chlorinated surface water and less chlorinated groundwater. The Cochran-Armitage trend test was used to evaluate whether there was a disinfection byproducts-related cancers (DBRCs) trend among communities receiving chlorinated water. Negative binomial regression was used to analyze the incidence rate.Results:A total of 11, 438 cancer cases were registered between 2012 and 2016, and DBRCs accounted for approximately 17%. The majority of the total cancer cases were female; 7,706 (67%). The prevalence of DBRCs was found to be higher in communities supplied with chlorinated water. From 2012 to 2016, the trend of colon cancer increased (β = 10.3, P value = .034); however, esophageal cancer decreased (β = −6.5, P value = .018). Approximately 56% of colorectal cancer patients and 53% of stomach cancer patients are known to be using chlorinated surface water for drinking regularly. In addition, approximately 57.1% and 54% of kidney and bladder cancer patients, respectively, used chlorinated surface water.Conclusion:The prevalence of DBRCs in this study was found to be high. The colon cancer trend increased substantially from 2012 to 2016. The prevalence of DBRCs was higher in communities supplied with chlorinated surface water. Similarly, the prevalence of DBRCs was higher among males than females. Further study is required to validate the association between DBRCs and water chlorination.

Drinking Water Source, Chlorinated Water, and Colorectal Cancer: A Matched Case-Control Study in Ethiopia.

Background:There is no study conducted on the association between disinfection byproducts (DBPs) in chlorinated drinking water and colorectal cancer (CRC) in Ethiopia. Therefore, this study aimed to determine the relation between chlorine based DBPs in drinking water and CRC in Addis Ababa, Ethiopia.Methods:A facility based matched case control study was conducted involving 224 cases and 448 population controls from June 2020 to May 2021. Cases were defined as histologically confirmed CRC cases. Cases were matched with controls by residence, age, and sex using frequency and individual matching. Geocoding of cases, health facility, and georeferencing of controls were carried out. Data was collected using a pretested structured questionnaire. Pearson Chi square and Fisher’s exact tests were employed to assess associations. Stratified analysis was used to detect confounding factors and effect modification. A multivariable conditional logistic regression was used to identify risk factors of CRC.Results:Of 214 CRC cases, 148 (69.2%) used chlorinated water whereas out of 428 controls 161 (37.6%) used chlorinated water. In the final regression model, drinking chlorinated surface water (adjusted matched odds ratio [adjusted mOR] = 2.6; 95% CI 1.7-4.0), history of swimming (adjusted mOR = 2.4; 95% CI 1.4-4.1), years at the place of current residence (adjusted mOR = 1.5; 95% CI 1.1-2.2), hot tap water use for showering (adjusted mOR; 3.8 = 95% CI 2.5-5.9) were significantly associated with CRC. The stratified analysis confirmed that smoking and meat ingestion were not effect modifiers and confounders.Conclusion:Drinking chlorinated water for extended years is a significant risk factor for CRC in Addis Ababa, Ethiopia. In addition, hot tap water use for showering, and swimming history are risk factors for CRC. This information is essential to design integrated interventions that consider chlorination by-products and exposure routes toward the prevention and control of CRC in Ethiopia. Initiating alternative methods to chlorine disinfection of drinking water is also essential.

Lifetime exposure to disinfection by-products and risk of cancer at six anatomic sites in Iowa, USA

Background: Disinfection by-products (DBPs) are suspected risk factors for multiple cancers. In our population-based case-control study in Iowa, we previously found moderate risks of bladder, brain, and rectal (but not colon, kidney, or pancreatic) cancers with duration of use of chlorinated surface water, known to have elevated DBP levels. We reanalyzed these data using quantitative estimates of lifetime DBP exposure. Methods: We identified 1,225 bladder, 586 colon, 566 rectal, 311 brain, 334 kidney, and 302 pancreatic cancer cases and 2,106 controls (1986-1989). We developed historical annual estimates of total trihalomethanes (TTHM) and the sum of five haloacetic acids (HAA5) levels for Iowa public water supplies. Using residential water source histories for each participant, we computed lifetime average exposure (µg/L) and exposure years above the U.S. maximum contaminant levels (MCL) for TTHM (>80 µg/L) and HAA5 (>60 µg/L); private well users were assumed to have no DBP exposure. We estimated odds ratios (ORs) and 95% confidence intervals (CI) for exposure quantiles from logistic regression models adjusted for potential confounders.Results: Rectal cancer risk was associated with lifetime average TTHM exposure above the 93.5th percentile (≥51.7 µg/L; OR=1.56, 95%CI=1.0-2.6; p-trend=0.02) and with 25+ years of exposure to levels above the MCL (OR=1.65, 95%CI=1.0-2.7; p-trend=0.05) but not with shorter duration; results were similar for men and women. Lifetime average TTHM exposure was not significantly associated with other cancers. 25+ years of exposure ≥80 µg/L TTHM was associated with increased odds of colon (OR=1.96, 95%CI=1.1-3.5), bladder (OR=1.38, 95% CI=1.0-2.0), and brain (OR=2.59, 95%CI=1.0-6.4) cancer among men, but not women or for shorter duration of exposure at this level. We observed sporadic positive associations with HAA5 exposures across cancer sites.Conclusions: Our findings contribute new quantitative evidence of associations between high levels of TTHM and rectal, colon, bladder, and brain cancers.

Unraveling the chemodiversity of halogenated disinfection by-products formed during drinking water treatment using target and non-target screening tools

To date, there is no analytical approach available that allows the full identification and characterization of highly complex disinfection by-product (DBP) mixtures. This study aimed at investigating the chemodiversity of drinking water halogenated DBPs using diverse analytical tools: measurement of adsorbable organic halogen (AOX) and mass spectrometry (MS)-based target and non-target analytical workflows. Water was sampled before and after chemical disinfection (chlorine or chloramine) at four drinking water treatment plants in Sweden. The target analysis had the highest sensitivity, although it could only partially explain the AOX formed in the disinfected waters. Non-target Fourier transform ion cyclotron resonance (FT-ICR) MS analysis indicated that only up to 19 Cl and/or Br-CHO formulae were common to all disinfected waters. Unexpectedly, a high diversity of halogenated DBPs (presumed halogenated polyphenolic and highly unsaturated compounds) was found in chloraminated surface water, comparable to that found in chlorinated surface water. Overall, up to 86 DBPs (including isobaric species) were tentatively identified using liquid chromatography (LC)-Orbitrap MS. Although further work is needed to confirm their identity and assess their relevance in terms of toxicity, they can be used to design suspect lists to improve the characterization of disinfected water halogenated mixtures.

Low toxicological impact of wastewaters on drinking water sources

Surface waters may contain varying levels of wastewater effluent associated with de facto reuse, which may influence their toxicological properties both prior to and following treatment. This study examined the genotoxic response of three surface waters containing a range of wastewater effluent (5%, 10%, and 25% by volume). The SOS Chromotest™ was used to assay the genotoxicity of both chlorinated and unchlorinated mixtures. Chlorinated mixtures were also analyzed for trihalomethanes (THMs), haloacetonitriles (HANs), and halonitromethanes (HNMs); their concentrations were used to calculate a relative toxicity index for each sample, based on published potencies in the comet assay and subsequently referred to as predicted genotoxicity. Wastewater effluents were observed to be reactive in the genotoxicity assay, whereas raw and chlorinated surface waters were not. Upon chlorination, surface waters containing 5% or 10% wastewater did not elicit a response and only modest effects were observed for higher wastewater ratios (25%). The measured SOS responses correlated well with predicted genotoxicity (R = 0.92) and THM concentrations (R = 0.92). This is important since THMs themselves are non-reactive in either the SOS or comet genotoxic assays, but their formation may serve as surrogates for non-regulated DBPs which drive toxic effects.

CH3NCl2 Formation from Chlorination of Carbamate Insecticides.

Carbamate insecticides, which are common micropollutants in surface waters, were found to generate dichloromethlyamine (DCMA) during chlorination. DCMA formation from other precursors has been reported previously; it is part of the emerging class of nitrogen-based disinfection byproducts (N-DBPs) of health concern in chlorinated water. However, there is a limited understanding about its formation, stability, and toxicity. Four carbamate insecticides (methomyl, carbofuran, carbaryl, and thiodicarb) were examined as DCMA precursors over a range of reaction conditions, based on variables of chlorine/precursor (Cl/P) molar ratio, pH, time, and temperature. DCMA was found to be the dominant volatile DBP to result from chlorination of all four carbamate insecticides, with molar yields ranging from 12% to 150% at a Cl/P molar ratio of 20. Further experiments indicated CH3NCl2 to be relatively stable, with a half-life of up to 35 h in water. The toxicity of CH3NCl2 was investigated using a bacterial bioluminescence inhibition test and survival of human lung tumor cells. The results of these toxicity assays indicated that CH3NCl2 is about 3 orders of magnitude more toxic than CHCl3. CH3NCl2 concentrations in the ppb range were observed to result from chlorination of surface water or tap water samples collected from several different locations in China. The results suggest that precursors to CH3NCl2 formation are ubiquitous and that CH3NCl2 poses a hazard to public health and the environment and should be considered in disinfection chemistry and water treatment.

Chlorination by-product levels in hot tap water: Significance and variability

People are exposed to chlorinated by-products (CBPs) through the consumption of cold tap water (CTW) (ingestion, inhalation, dermal contact) but also through the use of hot tap water (HTW) in such activities as showering and bathing (inhalation, dermal contact). This study focuses on the impact of residential water heating on CBP levels in tap water. Trihalomethane (THM) and haloacetic acid (HAA) levels were measured in the CTW and HTW of 50 residences located in two distribution systems supplied by chlorinated surface water during summer and winter. Results show important differences between CBP levels measured in cold and hot tap water. However, the magnitude of changes differs according to the specific species of THMs and HAAs, the season, the distribution system and the location within the same distribution system. Residential water heating led to an increase in average THM levels for the two distribution systems studied, which tended to be greater in winter. Residential water heating affected the two main HAA species found in the area studied (dichloroacetic (DCAA) and trichloroacetic (TCAA) acids) differently. In fact, the average DCAA levels increased due to water residential heating while a small change in average levels was observed for TCAA. However, the water heating impact on HAAs (in terms of importance and sometimes of tendency (increase vs. decrease)) may also differed between residences. The influence of seasons on the change in the average DCAA and TCAA levels (in μg/L) from residential water heating was not statistically significant except for TCAA levels in one distribution system. Results show the importance of considering site-specific characteristics of CTW (CBP level, temperature, residual chlorine, etc.) to estimate the levels of CBPs in HTW in CBP exposure assessment studies (and not to generalize for an entire population). The reported data can thus be useful in assessing for exposure to DBPs in epidemiological studies.

Identifying the underlying causes of biological instability in a full-scale drinking water supply system

Changes in bacterial concentration and composition in drinking water during distribution are often attributed to biological (in)stability. Here we assessed temporal biological stability in a full-scale distribution network (DN) supplied with different types of source water: treated and chlorinated surface water and chlorinated groundwater produced at three water treatment plants (WTP). Monitoring was performed weekly during 12 months in two locations in the DN. Flow cytometric total and intact cell concentration (ICC) measurements showed considerable seasonal fluctuations, which were different for two locations. ICC varied between 0.1–3.75 × 105 cells mL−1 and 0.69–4.37 × 105 cells mL−1 at two locations respectively, with ICC increases attributed to temperature-dependent bacterial growth during distribution. Chlorinated water from the different WTP was further analysed with a modified growth potential method, identifying primary and secondary growth limiting compounds. It was observed that bacterial growth in the surface water sample after chlorination was primarily inhibited by phosphorus limitation and secondly by organic carbon limitation, while carbon was limiting in the chlorinated groundwater samples. However, the ratio of available nutrients changed during distribution, and together with disinfection residual decay, this resulted in higher bacterial growth potential detected in the DN than at the WTP. In this study, bacterial growth was found to be higher (i) at higher water temperatures, (ii) in samples with lower chlorine residuals and (iii) in samples with less nutrient (carbon, phosphorus, nitrogen, iron) limitation, while this was significantly different between the samples of different origin. Thus drinking water microbiological quality and biological stability could change during different seasons, and the extent of these changes depends on water temperature, the water source and treatment. Furthermore, differences in primary growth limiting nutrients in different water sources could contribute to biological instability in the network, where mixing occurs.

Nitrogenous disinfection byproducts in English drinking water supply systems: Occurrence, bromine substitution and correlation analysis

Despite the recent focus on nitrogenous disinfection byproducts in drinking water, there is limited occurrence data available for many species. This paper analyses the occurrence of seven haloacetonitriles, three haloacetamides, eight halonitromethanes and cyanogen chloride in 20 English drinking water supply systems. It is the first survey of its type to compare bromine substitution factors (BSFs) between the haloacetamides and haloacetonitriles. Concentrations of the dihalogenated haloacetonitriles and haloacetamides were well correlated. Although median concentrations of these two groups were lower in chloraminated than chlorinated surface waters, median BSFs for both in chloraminated samples were approximately double those in chlorinated samples, which is significant because of the higher reported toxicity of the brominated species. Furthermore, median BSFs were moderately higher for the dihalogenated haloacetamides than for the haloacetonitriles. This indicates that, while the dihalogenated haloacetamides were primarily generated from hydrolysis of the corresponding haloacetonitriles, secondary formation pathways also contributed. Median halonitromethane concentrations were remarkably unchanging for the different types of disinfectants and source waters: 0.1 μg·mgTOC−1 in all cases. Cyanogen chloride only occurred in a limited number of samples, yet when present its concentrations were higher than the other N-DBPs. Concentrations of cyanogen chloride and the sum of the halonitromethanes were not correlated with any other DBPs.

Birth Defects and Disinfection By-Product Exposures and Source Water

Previous epidemiological studies suggest that women exposed to disinfection byproducts have an increased risk of delivering babies with neural tube, genitourinary system, and ventricular septal defects. The risk of birth defects (n=3,500) among all live births from 275 towns in Massachusetts was examined relative to different water sources, disinfection types, and disinfection byproduct concentrations using 2000 to 2004 data. Preliminary unadjusted and adjusted results for combined birth defects were largely null among the water source and disinfection exposure metrics. Adjusted odds ratios (aORs) ranged from 1.17 to 1.37 for obstructive urinary defects among births linked to drinking water treated with chlorine, chloramines, and other alternative disinfectants compared to untreated ground water systems. Compared to untreated ground water, increased aORs for cardiac defects were noted for chlorinated surface water (1.14; 95%CI=0.92, 1.41) and chloraminated water (1.08; 95%CI=0.88, 1.33). Increased aORs for hypospadias and epispadias were found for chlorinated surface water (1.19; 95%CI=0.80, 1.78) and chloraminated water (1.17; 95%CI=0.79, 1.72) compared to untreated ground water. Preliminary analyses showed no increased risk of combined birth defects for total trihalomethane or total haloacetic acid exposures compared to the lowest quintiles. Small increased aORs for ventricular septal defects were detected for the upper two brominated trihalomethane quintiles (aOR range=1.15-1.24), while increased risks for obstructive genitourinary defects were detected for the upper three bromodichloromethane (aOR range=1.10-1.51) and brominated trihalomethane (aOR range=1.61-1.91) quintiles. These preliminary data indicate larger risks for birth defects for brominated disinfection byproducts, but further analyses are needed to confirm these results. The views expressed herein are those of the authors only and do not necessarily reflect the views or policies of the USEPA.

Effect of water disinfection type on adverse fetal outcomes

The authors found small increased risks of preterm delivery (PTD) for chlorinated surface water, chlorinated groundwater, chloraminated water, and all other types of disinfected drinking water (range = 1.09–1.20) compared with untreated groundwater. Similar odds ratios (range = 1.08–1.16) were detected for small‐for‐gestational‐age (SGA) measurements and exposure to chlorinated surface water, chloraminated water, and other water disinfectants. A reduction in mean birth weight for these three exposure groups (range = 29–V39 g) was also found. Small differences in mean birth weight (≤ 16 g) were detected among chlorinated surface water users (versus chloraminated surface water), but odds ratios for SGA and PTD were comparable. Although associations were detected for disinfected drinking water exposure categories relative to untreated groundwater, the data suggest that risk of adverse birth outcomes among consumers of different types of disinfected drinking water were comparable in this study population.

THE EFFECT OF WATER SOURCE AND TYPE OF DISINFECTION IN BIRTH DEFECTS IN MASSACHUSETTS

Background and Aims: Previous research suggests that exposure to different water source, disinfection type (e.g., chlorinated surface water), and disinfection by-products may be associated with bir...

THE EFFECT OF DISINFECTION BY-PRODUCTS, WATER SOURCE, AND TYPE OF DISINFECTION IN PREGNANCY LOSS IN MASSACHUSETTS

Background and Aims: Previous research suggests that exposure to different water sources, disinfection type (e.g., chlorinated surface water), and disinfection by-products (DBPs) may be associated with pregnancy loss. We assessed the potential risk of water source, disinfection type, and DBPs on pregnancy loss in Massachusetts. Methods: We used birth and death certificate data on 510,264 pregnancies to examine this risk using 1998•2004 data from 275 Massachusetts towns. Fetal loss was defined as losses after the 20th week of gestation, and was examined using logistic regression. Results: Based on 2,488 pregnancy losses, preliminary unadjusted results indicate that mothers using public surface water systems had an increased risk of fetal loss (Odd Ratios (ORs) =1.37; 95% CI: 1.24,1.51) compared to mothers using ground water sources. Following adjustment for confounding by maternal risk factors (i.e., age, race, education, tobacco use), and disinfection type, this risk was attenuated (OR= 0.98; 95%CI: 0.85, 1.13). Compared to untreated water systems, mothers using chlorinated and chloraminated public water systems had an increased risk of fetal loss with ORs of1.15 (95%CI: 1.01, 1.33) and 1.36 (95% CI: 1.17, 1.58), respectively. ORs of 1.01 (95% CI: 0.85, 1.21) and 0.97 (95% CI: 0.79, 1.19) were found following adjustment for confounding by maternal risk factors and source water. No increased risk was found for the relationship between trihalomethanes (sum of chloroform, bromodichloromethane, dibromchloromethane, and bromoform) and fetal loss in any exposure category compared to the lowest (0 µg/L) category. Similarly, no increased risk was found for the relationship between haloacetic acids (sum of monochloroacetic acid, dichloroacetic acid, tricholoroacetic acid, bromoacetic acid, and dibromoacetic acid) and fetal loss in any exposure category compared to the lowest (0 µg/L) category. Conclusions: Further analyses will include fetal loss data from 1996-1997 and will utilize other statistical approaches such as Poisson regression.

AN ANALYSIS OF SPATIAL VARIABILITY IN DISINFECTION BY-PRODUCT CONCENTRATIONS FOR EXPOSURE ASSESSMENT APPLICATIONS

Background and Aims: Many epidemiological studies of disinfection by-products (DBPs) in public water systems (PWSs) rely on system average trihalomethane (i.e., THM4; sum of chloroform, dibromochloromethane, bromodichloromethane, and bromoform) and haloacetic acid (i.e., HAA5; sum of monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid) concentrations as surrogates for chemical-specific personal exposures. The study objective is to assess intrasystem variation and evaluate the utility of various methods for determining spatial variability of DBPs. Methods: To determine the utility of system-averages in estimating DBP levels, we assessed spatial variability in THM4 and HAA5 monitoring data for 144 and 132 PWSs in Massachusetts from 1995-2004. High spatial variability was defined using three methods. Methods 1 and 2 consider a PWS to have high spatial variability if the absolute difference between at least two sampling locations is •20 and •30 •g/L, respectively. Method 3 categorizes concentrations based on cut-points of regulatory significance (<40 µg/L, 40-80 µg/L, >80 µg/L), and a PWS is defined as having high spatial variation if same-day sample concentrations fall into multiple categories. Results: For THM4, 108 PWSs (75%) had high spatial variability according to Method 1, compared to 95 PWSs (66%) using Method 2. Results for HAA5 were lower with 79 PWSs (59%) and 60 PWSs (45%) based on Methods 1 and 2, respectively. Over half of these PWSs had high THM4 and HAA5 spatial variability for at least 25% of their sampling dates. Using only chlorinated surface water PWSs from 1996 (17 PWSs), we found comparable results from Methods 1 and 3, with 76% of PWSs having high spatial variation. Conclusions: The spatial variability noted within PWSs could result in misclassification bias if system averages are used to estimate individual-level DBP exposures. Therefore, exposure assessment approaches should target systems with minimal spatial variability for epidemiological application.

English

The shortage of potable water for irrigation of food crops in semi-arid developing countries led to the use of alternative sources of water. Wastewater is gaining importance for productive use in agriculture throughout the world. A widely used and efficient method to reduce the occurrence of waterborne diseases in numerous wastewater plants is water chlorination. In early 1970s, some volatile halogenated organic compounds such as chloroform were identified in chlorinated surface waters containing high levels of natural organic material. Generally, the trihalomethanes (THMs), including chloroform, bromodicholoromethane, dibromochloromethane and bromoform were the most prevalent in chlorinated surface water. Predominant research studies focused on the carcinogenic and mutagenic properties of these compounds in treated wastewater. But little attention was paid to how these compounds in treated wastewater could affect crop performance in agriculture, physiological changes amongst crop varieties and the build-up of these organic compounds in edible plant tissues with persistent use of treated waste-water. A probable reason for this was the absence of the practice of wastewater irrigation in food crop agriculture in the past. Current knowledge on the trihalomethanes and possible plant interactions with this group of volatile organic compounds are assessed in this review.   Key words: Antioxidants, biomagnification, chlorophyll, metabolites, oxidative-stress, photosynthesis, phytotoxicity, seed germination, trihalomethanes.

Development of a U.S. EPA Drinking Water Method for the Analysis of Selected Perfluoroalkyl Acids by Solid-Phase Extraction and LC-MS-MS

A drinking water method for perfluoroalkyl acids (PFAAs) is presented that addresses the occurrence monitoring needs of the U.S. Environmental Protection Agency (EPA) for a future unregulated contaminant monitoring regulation (UCMR). This paper describes the challenges associated with developing an analytical method for 14 PFAAs that will be used for drinking water occurrence monitoring. The method employs solid-phase extraction with analysis by liquid chromatography-tandem mass spectrometry (LC-MS-MS). The final method preservation scheme requires that samples be stored in polypropylene bottles and that they be buffered and free chlorine removed with Trizma buffer. Mean recoveries of chlorinated surface water samples fortified with the PFAAs at 40-100 ng/L (except for the perfluorooctane-sulfonamido-acetic acids at 200 ng/L) are 85-112% with < 5% relative standard deviation. Single laboratory minimum reporting limits of 2.9-14 ng/L are demonstrated with this methodology. The final method meets all of the EPA UCMR survey requirements for sample collection and storage, precision, accuracy, and sensitivity and is expected to be proposed for use under a future UCMR.

Serological responses toCryptosporidium-specific antigens in Czech populations with different water sources

Serological responses to Cryptosporidium-specific antigens (15/17 and 27 kDa) were compared among populations in four areas of the Czech Republic that use drinking water from clearly defined sources: (1) wells in a fractured sandstone aquifer, (2) riverbank infiltration, or (3) two different filtered and chlorinated surface waters. Among persons surveyed in the area with riverbank-infiltration water, 33% had a strong serological response to the 15/17-kDa antigen group whereas, in the other three areas, over 72% of persons had a strong response. These response differences suggest that Cryptosporidium exposures and infection were lower in the area with bank infiltration. The large percentage of the study population with a strong serological response to both antigens suggests high levels of previous infections that may have resulted in protective immunity for cryptosporidiosis. This may be one reason why no waterborne cryptosporidiosis outbreaks and few cases of cryptosporidiosis have been reported in the Czech Republic.

A Large Outbreak of Hepatitis E among a Displaced Population in Darfur, Sudan, 2004: The Role of Water Treatment Methods

The conflict in Darfur, Sudan, was responsible for the displacement of 1.8 million civilians. We investigated a large outbreak of hepatitis E virus (HEV) infection in Mornay camp (78,800 inhabitants) in western Darfur. To describe the outbreak, we used clinical and demographic information from cases recorded at the camp between 26 July and 31 December 2004. We conducted a case-cohort study and a retrospective cohort study to identify risk factors for clinical and asymptomatic hepatitis E, respectively. We collected stool and serum samples from animals and performed a bacteriological analysis of water samples. Human samples were tested for immunoglobulin G and immunoglobulin M antibody to HEV (for serum samples) and for amplification of the HEV genome (for serum and stool samples). In 6 months, 2621 hepatitis E cases were recorded (attack rate, 3.3%), with a case-fatality rate of 1.7% (45 deaths, 19 of which involved were pregnant women). Risk factors for clinical HEV infection included age of 15-45 years (odds ratio, 2.13; 95% confidence interval, 1.02-4.46) and drinking chlorinated surface water (odds ratio, 2.49; 95% confidence interval, 1.22-5.08). Both factors were also suggestive of increased risk for asymptomatic HEV infection, although this was not found to be statistically significant. HEV RNA was positively identified in serum samples obtained from 2 donkeys. No bacteria were identified from any sample of chlorinated water tested. Current recommendations to ensure a safe water supply may have been insufficient to inactivate HEV and control this epidemic. This research highlights the need to evaluate current water treatment methods and to identify alternative solutions adapted to complex emergencies.

Volatile organohalogen compounds in human urine: The effect of environmental exposure

The paper presents the results of determination of volatile organohalogen compounds (VOX) in urine samples from subjects exposed to these compounds in their workplaces and through consumption of chlorinated tap water. The analytes were isolated and preconcentrated from the complex urine samples using the thin layer headspace (TLHS) technique with autogenous generation of the liquid sorbent. Final gas chromatographic determination was carried out by direct aqueous injection with electron capture detection (DAI-ECD). The results indicate that only a small fraction (<4%) of the VOX input is excreted with urine in the non-metabolized form. A positive correlation was found between the occupational levels of VOX in the workplace and their levels in urine. VOX levels in the urine of subjects not exposed to them in the workplace were significantly lower. Their presence in the organisms was most probably related to consumption of tap water produced by chlorination of surface waters.