Chlorinated Tap Water Research Articles

Aquatic photochemistry of chlorinated triclosan derivatives: Potential source of polychlorodibenzo‐P‐dioxins

Triclosan (TCS; 5-chloro-2-(2,4-dichlorophenoxy)phenol), a common antimicrobial agent, may react with residual chlorine in tap water during transport to wastewater treatment plants or during chlorine disinfection of wastewater, generating chlorinated TCS derivatives (CTDs): 4,5-dichloro-2-(2,4-dichlorophenoxy)phenol (4-Cl-TCS), 5,6-dichloro-2-(2,4-dichlorophenoxy)phenol (6-Cl-TCS), and 4,5,6-trichloro-2-(2,4-dichlorophenoxy)phenol (4,6-Cl-TCS). The photochemistry of CTDs was investigated due to the potential formation of polychlorodibenzo-p-dioxin (PCDD) photoproducts. Photolysis rates were highly dependent upon CTD speciation, because the phenolate species degraded 44 to 586 times faster than the phenol forms. Photolysis quantum yield values for TCS, 4-Cl-TCS, 6-Cl-TCS, and 4,6-Cl-TCS of 0.39, 0.07, 0.29, and 0.05, respectively, were determined for the phenolate species. Photolyses performed in Mississippi River and Lake Josephine (USA) waters gave similar quantum yields as buffered, pure water at the same pH, indicating that indirect photolysis processes involving photosensitization of dissolved organic matter are not competitive with direct photolysis. The photochemical conversion of the three CTDs to PCDDs under solar irradiation was confirmed in natural and buffered, pure water at yields of 0.5 to 2.5%. The CTD-derived PCDDs possess higher toxicities than 2,8-dichlorodibenzo-p-dioxin, a previously identified photoproduct of TCS, due to their higher chlorine substitution in the lateral positions. The load of TCS- and CTD-derived PCDDs to United States surface waters is estimated to be between 46 and 92 g toxicity equivalent units per year. Other identified photoproducts of each CTD were 2,4-dichlorophenol and reductive dechlorination products.

Exploring Amino Acid Side Chain Decomposition Using Enzymatic Digestion and HPLC-MS: Combined Lysine Transformations in Chlorinated Waters

Characterizing the transformations of polypeptides is important across a broad range of scientific disciplines. As polypeptides are an important constituent of dissolved organic matter within seawater and freshwater, it is important to understand their (bio)geochemical fate. Oxidants, formed in blood as part of the immunological response or applied to waters for disinfection, react with polypeptides to form transformation products that may exert toxicity. An analytical method was developed to characterize and quantify modifications to the side chains of amino acid residues within polypeptides. Enzymatic digestion of polypeptides using Pronase E, a protease cocktail, proved preferable to common strong acid digestion techniques, because the circumneutral pH conditions employed during enzymatic digestion prevent artifacts arising from extreme pH conditions. Lysine nitrile, one of the predicted transformation products of lysine residues within polypeptides, was destroyed during strong acid digestion but not enzymatic digestion. Due to the potential variability in enzymatic digestion efficiencies, the liberation of a mass-labeled leucine monomer from an octapeptide spiked standard was employed as a measure of complete digestion efficiency for each sample and enabled quantification of modified amino acid residues within polypeptides. A multivariate statistical analysis was conducted to evaluate the influence on digestion efficiency of Pronase E loadings, salinity, natural organic matter concentration, and pH across the range of conditions relevant to blood, seawater, and concentrated freshwaters and disinfected drinking/recreational waters. At Pronase E loadings of 10 mg, the analysis indicated that digestion efficiencies ranged from 25 to 55% over the range of conditions expected for typical drinking waters concentrated from 1 L to 10 mL. The analytical method was applied to triplicate 1 L samples of a chlorinated tap water and a chlorinated indoor pool water. For the tap water, the digestion efficiency was 47.2% (+/-11.1% relative standard deviation), and the lysine nitrile concentration was 104.6 ng/L (+/-6.8 ng/L standard deviation). For the pool water, the digestion efficiency was 23% (+/-15% relative standard deviation); although the occurrence of lysine nitrile was verified, matrix effects must be overcome for quantification.

Analysis of the survival of Venezuelan equine encephalomyelitis virus and possible viral simulants in liquid suspensions

To compare the inactivation rate of Venezuelan equine encephalomyelitis (VEE) virus in liquids to that of Sindbis virus (SV, another alphavirus) and to a bacteriophage (MS2) generally used as a viral simulant in the development of countermeasures in biodefense. Viruses were inoculated into liquids and viral titres were determined at various times postinoculation. The viruses were stable in distilled-deionized (dd) water at 4 degrees C during the 21 days of the study. The inactivation rates of VEE and SV in dd water at 21 and 30 degrees C were very similar (between 0.12 and 0.14 log(10) per day), while MS2 was three-fold slower. In tap water (chlorine content between 4 and 5 ppm) at 21 degrees C, VEE and SV were inactivated at twice the rate measured in dd water. The inactivation rates of VEE and SV were similar to each other and faster than MS2 in all liquids tested. VEE is likely to remain viable for many days after release into water, snow, or even chlorinated tap water. SV can be used to estimate the persistence of VEE in liquids, but using MS2 as a simulant would overestimate of the stability of VEE.

Solid phase microextraction procedure for the determination of alkylphenols in water by on-fiber derivatization with N- tert-butyl-dimethylsilyl- N-methyltrifluoroacetamide

The solid phase microextraction (SPME) technique with on-fiber derivatization was evaluated for the analysis of alkylphenols (APs), including 4- tert-octylphenol (4- t-OP), technical nonylphenol isomers (t-NPs) and 4-nonylphenol (4-NP), in water. The 85 μm polyacrylate (PA) fiber was used and a two-step sample preparation procedure was established. In the first step, water sample of 2 mL was placed in a 4 mL PTFE-capped glass vial. Headspace extraction of APs in water was then performed under 65 °C for 30 min with 800 rpm magnetic stirring and the addition of 5% of sodium chloride. In the second step, the SPME fiber was placed in another 4 mL vial, which contained 100 μL of N- tert-butyl-dimethylsilyl- N-methyltrifluoroacetamide (MTBSTFA) with 1% tert-butyl-dimethylchlorosilane (TBDMCS). Headspace extraction of MTBSTFA and on-fiber derivatization with APs were performed at 45 °C for 10 min. Gas chromatography/mass spectrometry (GC/MS) was used for the analysis of derivatives formed on-fiber. The adsorption-time profiles were also examined. The precision, accuracy and method detection limits (MDLs) for the analysis of all the APs were evaluated with spiked water samples, including detergent water, chlorinated tap water, and lake water. The relative standard deviations were all less than 10% and the accuracies were 100 ± 15%. With 2 mL of water sample, MDLs were in the range of 1.58–3.85 ng L −1. Compared with other techniques, the study described here provided a simple, fast and reliable method for the analysis of APs in water.

Seasonal variations in the household exposures of Korean housewives to volatile tap water disinfection by-products

This study was conducted to compare housewives' winter and summer exposures to volatile disinfection by-products (DBPs) in chlorinated tap water. A total of 60 households were visited for this purpose: 27 in winter and 33 in summer. Each subject was given a questionnaire regarding general tap water use, household ventilation time, and activities related to water use. Tap water, household air, and exhaled breath samples were also collected during the visits. All of the subjects answered that they consumed tap water after either thermal treatment or purification through filtration systems. A longer ventilation time in winter than in summer resulted in a higher inhalation exposure for housewives during that season. Estimated chronic daily intakes calculated for winter and summer showed that in winter, the greatest risk at home is inhalation exposure while resting at home, whereas in summer, it is showering. In both seasons, the ingestion route can be discounted, because tap water is processed before consumption, eliminating the volatile DBPs. From this study, it is evident that the inhalation of household air while resting at home cannot be ignored in risk assessment. Moreover, the fact that water is normally boiled or filtered before use should also be considered.

Determination of iodoacetic acid using liquid chromatography/electrospray tandem mass spectrometry

A rapid analytical method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) using electrospray ionization in negative ion detection mode was developed for the analysis of underivatized iodoacetic acid in water. The method was applied to model reaction mixtures in the study of the formation of iodoacetic acid after chlorinated tap water was boiled in the presence of potassium iodide or iodized table salt. Samples can be directly analyzed by the LC/MS/MS system without extraction or chemical derivatization. Limit of detection was determined to be 0.3 microg/L (or 0.3 ng/mL) and limit of quantitation was about 1 microg/L (1 ng/mL).

Predictors of personal air concentrations of chloroform among US adults in NHANES 1999–2000

Volunteer studies suggest that showering/bathing with chlorinated tap water contributes to daily chloroform inhalation exposure for the majority of US adults. We used data from the 1999-2000 US National Health and Nutrition Examination Survey (NHANES) and weighted multiple linear regression to test the hypothesis that personal exposure microevents such as showering or spending time at a swimming pool would be significantly associated with chloroform levels in 2-3 day personal air samples. The NHANES data show that eight of 10 US adults are exposed to detectable levels of chloroform. Median (1.13 microg/m(3)), upper percentile (95th, 12.05 microg/m(3)), and cancer risk estimates were similar to those from recent US regional studies. Significant predictors of log personal air chloroform in our model (R(2)=0.34) included age, chloroform concentrations in home tap water, having no windows open at home during the sampling period, visiting a swimming pool during the sampling period, living in a mobile home/trailer or apartment versus living in a single family (detached) home, and being Non-Hispanic Black versus Non-Hispanic White, although the race/ethnicity estimates appear influenced by several outlying observations. Reported showering activity was not a significant predictor of personal air chloroform, possibly due to the wording of the NHANES shower question. The NHANES measurements likely underestimate true inhalation exposures since subjects did not wear sampling badges while showering or swimming, and because of potential undersampling by the passive monitors. Research is needed to quantify the potential difference.

The development of point-of-use water filters as sampling devices in bioforensics: extent of microbial sorption and elution

The foundational idea for this project is that household faucet-mounted water filters may be used as bioforensic sampling devices to detect the extent of a potential bioagent release in domestic water supplies. An optimized eluent solution was determined experimentally by quantifying recoveries of microorganisms from point-of-use (POU) drinking water filters. The optimized extraction protocol was then used in mock bioagent release experiments to determine the feasibility of POU filters as bioforensic sampling devices. Bacillus atrophaeus spores, Escherichia coli and PP7 virus were exposed to filters and the number of attached organisms was determined by enumerating the unattached organisms on selective agar media. Subsequently, the filters were eluted and the percent of extracted organisms was determined based on the number of attached organisms. Two popular brands of carbon block filters retained 92%-99% of representative virus, spore and vegetative bacteria. In back-flush elutions of single filters, the most efficient eluent was identified as a combination of 1% peptone and 1% Tween-80, and extraction recovered 25.4% (+/-17.5%) of attached E. coli, 20.4% (+/-3.6%) of B. atrophaeus spores, and 9.4% (+/-5.2%) of PP7 virions (+/- standard deviations). In bioagent release studies in which filters were challenged with 100 agents mL(-1), greater than 99% of the spores were retained by the filters, and the percent of attached spores that were recovered ranged from 10.4% at day 0 to 4.3% five days after the release event (averaged from five separate experiments). In contrast, E. coli, Salmonella typhimurium and PP7 virus were rapidly inactivated in the chlorinated tap water, indicating their improbable survival in chlorinated water supplies. It is therefore concluded that household water filters can be used as microbial sampling devices for bioforensic applications in the event of a bioagent release in domestic drinking water supplies.

Online in situ analysis of selected semi-volatile organic compounds in water by automated microscale solid-phase extraction with large-volume injection/gas chromatography/mass spectrometry

A fully automated analytical method was developed for the online in situ analysis of selected semi-volatile organic compounds in water. The method used a large-volume injection/gas chromatography/mass spectrometry coupled with a fully automated microscale solid-phase extraction technique, which was based on x– y– z robotic techniques. Water samples were extracted by using a 96-well solid-phase extraction plate. For most analytes included in this study, the obtained linear calibrations ranged from 0.05 to 5.0 μg/L with correlation coefficients of 0.996–1.000, the method detection limits were less than 0.1 μg/L, and the relative recoveries were in the range of 70–120% with a relative standard deviation of less than 15% for fortified reagent water samples. The applications to chlorinated tap water, well water, and river water have been validated. The obtained results were similar to those resulting from fortified reagent water samples for all analytes except metribuzin, bromacil, aldrin, and methoxychlor. Matrix effects were observed for these analytes. In general, this fully automated analytical method was rugged, reliable, and easy to operate, and was capable of providing real-time data to water treatment and distribution systems as well as water reservation and protection systems. In addition, the method could reduce the analytical costs associated with sample collection, transportation, storage, and preparation.

Comparison of viability and infectivity of Cryptosporidium parvum oocysts stored in potassium dichromate solution and chlorinated tap water

The present study was undertaken to compare the viability and infectivity of Cryptosporidium parvum oocysts that had been stored for 1, 4, 7, 10, 13, 16, 20, 25 and 30 months at 4 °C in 2.5% potassium dichromate (Cr) or chlorinated tap water, respectively. An excystation protocol was performed in vitro to evaluate viability. One hundred and eighty female BABL/c mice were used to evaluate the infectivity of oocysts by investigating the prepatent period of C. parvum infection, the quantity of oocysts excreted, and the number of parasites that colonized the villi of the ileum. The results showed that C. parvum oocysts preserved in Cr for 1–16 months or in water for 1–13 months were capable of excystation in vitro and infection of mice. The excystation rates of oocysts and the prepatent periods in mice infected by oocysts stored in Cr and water were not significantly different ( p > 0.05), and there was a strong correlation between prepatent period and duration of oocyst storage (Cr: R 2 = 0.92 ; water: R 2 = 0.98). There were no significant differences in oocyst shedding from feces or parasitism of the terminal ilea of mice by Cryptosporidia between the two storage media ( p > 0.05). In conclusion, C. parvum oocysts may be stored at 4 °C in water instead of Cr for the purposes of laboratory research. However, the presence of viable C. parvum oocysts in water is a severe challenge to the drinking water treatment industry.

Liquid Chromatography−Tandem Mass Spectrometry Application, for the Determination of Extracellular Hepatotoxins in Irish Lake and Drinking Waters

A novel method for the determination of hepatotoxins; microcystins (MCs), and nodularin (Nod) in lake water and domestic chlorinated tap water has been developed using liquid chromatography hyphenated with electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS). Optimization of the mass spectrometer parameters and mobile-phase composition was performed to maximize the sensitivity and reproducibility of the method. Detection of the hepatotoxins was carried out using multiple reaction monitoring experiments, thus improving the selectivity of the method. A total ion chromatogram and a precursor ion scan on ion m/z 135 was also applied to all samples to detect unknown microcystins or microcystins for which there are no standards available. A comprehensive validation of the LC-ESI-MS/MS method was completed that took into account matrix effects, specificity, linearity, accuracy, and precision. Good linear calibrations were obtained for MC-LR (1-200 microg/L; R2=0.9994) in spiked lake and tap water samples (1-50 microg/L; R2=0.9974). Acceptable interday repeatability was achieved for MC-LR in lake water with RSD values (n=9) ranging from 9.9 (10 microg/L) to 5.1% (100 microg/L). Excellent limits of detection (LOD) and limits of quantitation (LOQ) were achieved with spiked MCs and Nod samples; LOD=0.27 microg/L and LOQ=0.90 microg/L for MC-LR in the "normal linear range" and LOD=0.08 microg/L and LOQ=0.25 microg/L in the "low linear range" in both lake and chlorinated tap water. Similar results were obtained for a suite of microcystins and nodularin. This sensitive and rapid method does not require any sample preconcentration, including the elimination of solid-phase extraction (SPE) for the effective screening of hepatotoxins in water below the 1 microg/L WHO provisional guideline limit for MC-LR. Furthermore, SPE techniques are time-consuming, nonreproducible at trace levels, and offer poor recoveries with chlorinated water. The application of this LC-ESI-MS/MS method for routine screening of hepatotoxins in lake and chlorinated tap water (average Cl2=0.23 mg/L) is achieved and this study represents the first direct method for the screening of hepatotoxins in chlorinated tap water.

Degradation of Vulcanised Rubber Products – Problems and Solutions (Degradation by Residual Chlorine in Tap Water, Metals and Ozone Due to Deterioration in the Global Environment)

Degradation of Vulcanised Rubber Products – Problems and Solutions (Degradation by Residual Chlorine in Tap Water, Metals and Ozone Due to Deterioration in the Global Environment)

Evaluating the Effect of Baquacil® and Sanosil® on Salmonella spp., in the Aquatic Habitat of the Red-Eared Slider Turtle, Trachemys scripta elegans

ABSTRACT Turtle-associated salmonellosis was first recognized as a public health concern in the 1960's, particularly due to an increase in the incidence of disease among children. In response to the public health threat, the United States Food and Drug Administration (FDA) implemented regulations in 1975 restricting the sale of turtles with a carapace length <10.2 cm. Since that time, the turtle industry has pursued research to eliminate Salmonella spp. Recent work has focused on identifying non-antibiotic products to reduce or eliminate Salmonella and reverse the FDA regulations. Baquacil® and Sanosil® are commercial non-antibiotic, antimicrobial products. Eighty-four red-eared slider turtle hatchlings, Trachemys scripta elegans, were used to evaluate the efficacy of these products as a method to suppress Salmonella spp., in the turtles' habitats. The turtles were maintained individually in plastic containers that contained chlorinated tap water, chlorinated tap water and 10, 50, or 100 ppm Sanosil®, or ...

Formation of iodoacetic acids during cooking: Interaction of iodized table salt with chlorinated drinking water

Iodoacetic and chloroiodoacetic acids were formed when municipal chlorinated tap water was allowed to react with iodized (with potassium iodide) table salt or with potassium iodide itself. Iodoacetic acid was recently shown to be a potent cytotoxic and genotoxic agent. For analysis, samples were extracted with t-amyl methyl ether and converted to the corresponding methyl esters using methanol and sulfuric acid. The concentration of iodoacetic acid was determined by gas chromatography-mass spectrometry (GC-MS) using an authentic standard. The identities of iodoacetic and chloroiodoacetic acids were further confirmed by gas chromatography-high-resolution mass spectrometry (GC-HRMS). Certain influences of sodium hypochlorite and humic acid as well as the concentration of potassium iodide on the yields of these acids were investigated. The concentration of iodoacetic acid in tap water samples boiled with 2 g l−1 of iodized table salt was found to be in the 1.5 µg l−1 range, whilst the concentration of chloroiodoacetic acid was estimated to be three to five times lower.

Formation of halogenated by-products of parabens in chlorinated water

Chemical transformations of four alkyl esters of p-hydroxybenzoic acid, parabens, in chlorinated water samples are investigated. Quantification of the parent species and identification of their reaction by-products were performed using gas chromatography in combination with mass spectrometry. Experiments were accomplished considering free chlorine and paraben concentrations at the mg L −1 and μg L −1 level, respectively. Concentration of water samples, using solid-phase extraction, and silylation of the target species were carried out in order to improve the detectability of parent species and their possible transformation products, achieving quantification limits at the low ng L −1 level. Under employed experimental conditions, the decrease in the concentrations of parabens followed pseudo-first-order kinetics. Half-lives values obtained for model ultrapure water solutions were in good agreement with those observed in tap water samples. For the first type of sample, only two by-products were detected for each paraben. They corresponded to chlorination of the aromatic ring in one or two carbons situated in ortho-positions to the hydroxyl group. Both species were also generated after the addition of parabens to chlorinated tap water. Moreover, three new transformation products were noticed for each parent compound. They were identified as bromo- and bromochloro-parabens, formed due to the existence of traces of bromide in tap water sources. Experiments carried out by mixing paraben-containing personal care products with tap water, containing free chlorine, confirmed the formation of all above described halogenated by-products. In addition, the presence of the di-chlorinated forms of methyl and propyl paraben has been detected for first time in raw sewage water samples.

Aquatic degradation of triclosan and formation of toxic chlorophenols in presence of low concentrations of free chlorine

The degradation of 2-(2,4-dichlorophenoxy)-5-chlorophenol (triclosan) in chlorinated water samples was investigated. Sensitive determination of the parent compound and its transformation products was achieved by gas chromatography with mass spectrometry detection after sample concentration, using a solid-phase extraction sorbent and silylation of the target compounds. Experiments were accomplished using ultrapure water spiked with chlorine and triclosan concentrations in the low mg/l and ng/ml ranges respectively. Chlorination of the phenolic ring and cleavage of the ether bond were identified as the main triclosan degradation pathways. Both processes led to the production of two tetra- and a penta-chlorinated hydroxylated diphenyl ether, as well as 2,4-dichlorophenol. The formation of 2,3,4-trichlorophenol was not detected in any experiment; however, significant amounts of 2,4,6-trichlorophenol were noticed. All of these five compounds were also identified when triclosan was added to tap-water samples with free chlorine concentrations below 1 mg/l. Minor amounts of three di-hydroxylated phenols, containing from one to three atoms of chlorine in their structures, were also identified as unstable triclosan chlorination by-products. The analysis of several raw wastewater samples showed the co-existence of important concentrations of triclosan and its most stable by-products (2,4-dichlorophenol and 2,4,6-trichlorophenol), reinforcing the potential occurrence of the described transformations when products containing triclosan are mixed with chlorinated tap water.

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.

Airborne Exposure to Trihalomethanes from Tap Water in Homes with Refrigeration-Type and Evaporative Cooling Systems

This study evaluates airborne concentrations of common trihalomethane compounds (THM) in selected living spaces of homes supplied with chlorinated tap water containing >85 ppb total THM. Three small homes in an arid urban area were selected, each having three bedrooms, a full bath, and approximately 1000 square feet; two homes had standard (refrigeration-type) central air conditioning and the third had a central evaporative cooling system (“swamp cooler”). A high-end water-use pattern was used at each home in this exposure simulation. THM were concurrently measured on 4 separate test days in tap water and air in the bathroom, living room, the bedroom closest to the bathroom, and outside using Summa canisters. Chloroform (trichloromethane, TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) concentrations were quantified using U.S. EPA Method TO-14. The apparent volatilization fraction consistently followed the order: TCM >BDCM >DBCM. Relatively low airborne THM concentrations (similar to outdoors) were found in the living room and bedroom samples for the home with evaporative cooling, while the refrigeration-cooled homes showed significantly higher THM levels (three- to fourfold). This differential remained after normalizing the air concentrations based on estimated THM throughput or water concentrations. These findings indicate that, despite higher throughput of THM-containing water in homes using evaporative coolers, the higher air exchange rates associated with these systems rapidly clears THM to levels similar to ambient outdoor concentrations.The data collection and preliminary data analysis were funded by defendants in a toxic tort lawsuit who were attempting to validate the accuracy of modeling assumptions and results that were offered in that litigation. The time and costs of writing this article were borne by the authors. The assistance of Tom Flahive, Gwen Corbett, Rick Hamaker, and Steve Hoyt was greatly appreciated.A poster session including the data described in this report was presented at the Society of Toxicology annual meeting and published in the following abstract: Paustenbach, D. J., Richter, R. O., Suder, D., Corbett, G. E., Flahive, T. P., and Kerger, B. D. 1998. Comparison of measured and model-estimated indoor concentrations of airborne chloroform from use of residential tap water. Toxicological Sciences 42(1-S):40–41.

Evaluating the Efficacy of Baquacil® Against Salmonella sp. in the Aquatic Habitat of the Red-Eared Slider, Trachemys scripta elegans

ABSTRACT Turtle-associated salmonellosis (TAS) in humans has been a concern of public health officials since the 1960's. The rising incidence of TAS in young children during the late 1960's and early 1970's eventually led to the implementation of inter- and intrastate regulations on the sale of chelonians less than 10.2-cm in total length in the United States of America. Although attempts to eliminate Salmonella spp. in chelonians using antibiotics have been made, they have not been successful in reducing prevalence to levels that would reverse current regulations. Baquacil® is a commercial algistat and microbicide. Fifty-five red-eared slider turtles, Trachemys scripta elegans, were used to evaluate the efficacy of Baquacil® as a method to suppress Salmonella sp. in the sliders habitat. The sliders were maintained individually in plastic containers that contained either chlorinated tap water, dechlorinated tap water and 25 ppm Baquacil®, or dechlorinated tap water and 50 ppm Baquacil®. Water samples were...

Mutagen X and chlorinated tap water are recombinagenic in yeast

This study determines the effects of a water disinfection by-product, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5 H)-furanone (also known as mutagen X or MX) and chlorinated tap water on genomic instability in the yeast Saccharomyces cerevisiae. Tap water samples collected from Cherepovets (Russia) and Boston (MA, USA), were extracted using XAD absorption and ethyl acetate elution. MX and these water extracts were then tested for their ability to induce intrachromosomal recombination (deletions or DEL events), interchromosomal recombination (ICR) and aneuploidy (ANEU) using the yeast DEL assay. MX strongly induced DEL, ICR and ANEU events with a positive dose response and no threshold. Cherepovets tap water induced DEL and ICR events while evidence of ANEU induction was weak. The DEL induction potencies were stronger at higher concentrations. The estimated contribution of MX to DEL induction varied from over 50% at low concentrations (which is comparable to a typical contribution of MX to Ames mutagenicity of tap water) to between 2 and 10% at highest concentrations. For Boston tap water, there was only weak evidence of DEL induction and no evidence of ICR and ANEU induction. This is consistent with the results of other studies, which reported much higher concentrations of MX and stronger Ames mutagenicity in Cherepovets tap water than in Boston tap water.