Programmed death-1 inhibitor for occupational intrahepatic cholangiocarcinoma caused by chlorinated organic solvents.

Highlight Tanaka and Kubo reported the first case of recurrent occupational cholangiocarcinoma treated with programmed death-1 inhibitor. A programmed death-1 inhibitor was administered every 2 weeks for para-aortic lymph node metastasis after curative hepatectomy. After seven cycles of administration, positron emission tomography demonstrated diminished lymph node size without 18 F-fluorodeoxy glucose uptake.

Genotoxicity of non-alcoholic mouth rinses: A micronucleus and nuclear abnormalities study with fluorescent microscopy.

AIM: The aim of the present study was to evaluate the genotoxicity of non-alcoholic mouth rinses on buccal epithelial cells using a micronucleus test. METHODS: A total of 105 patients were selected and randomly divided into five groups. Four different mouth rinses and normal saline were given for 2 weeks' duration, and cytological smears were collected before and after exposure. These smears were subjected to micronucleus (MN) and other nuclear abnormalities (ONA) tests using acridine orange stain, and their frequencies were obtained in 500 buccal epithelial cells. The statistical analysis included mean, χ2 -test, analysis of variance, and post-hoc analysis by Bonferroni test. RESULTS: Micronucleated cells (P < .00) and MN (P < .00) were higher in individuals exposed to chlorhexidine (CHX), followed by chlorine dioxide (ClO2 ), potassium nitrate (KNO3 ), and sodium fluoride (NaF), amine fluoride (AmF), and normal saline. ONA were greater (P < .00) in individuals exposed to CHX, followed by ClO2 , AmF, KNO3 , and NaF and normal saline. Overall, the results showed that genotoxic damage was greater in the case of CHX, followed by ClO2 , KNO3 , and NaF, AmF, and normal saline. CONCLUSION: Chronic exposure to mouth rinses can cause genotoxic damage to buccal epithelial cells. Long-term injudicious and inadvertent use of mouth rinses should be discouraged.

Protein quality control under oxidative stress conditions.

Accumulation of reactive oxygen and chlorine species (RO/CS) is generally regarded to be a toxic and highly undesirable event, which serves as contributing factor in aging and many age-related diseases. However, it is also put to excellent use during host defense, when high levels of RO/CS are produced to kill invading microorganisms and regulate bacterial colonization. Biochemical and cell biological studies of how bacteria and other microorganisms deal with RO/CS have now provided important new insights into the physiological consequences of oxidative stress, the major targets that need protection, and the cellular strategies employed by organisms to mitigate the damage. This review examines the redox-regulated mechanisms by which cells maintain a functional proteome during oxidative stress. We will discuss the well-characterized redox-regulated chaperone Hsp33, and we will review recent discoveries demonstrating that oxidative stress-specific activation of chaperone function is a much more widespread phenomenon than previously anticipated. New members of this group include the cytosolic ATPase Get3 in yeast, the Escherichia coli protein RidA, and the mammalian protein α2-macroglobulin. We will conclude our review with recent evidence showing that inorganic polyphosphate (polyP), whose accumulation significantly increases bacterial oxidative stress resistance, works by a protein-like chaperone mechanism. Understanding the relationship between oxidative and proteotoxic stresses will improve our understanding of both host-microbe interactions and how mammalian cells combat the damaging side effects of uncontrolled RO/CS production, a hallmark of inflammation.

[Endoscopic diagnosis of local chemical burn of mucous membranes of the stomach, induced with the purpose of simulation of gastric ulcer].

With the purpose of improvement of diagnosis of induced gastric ulcer were examined 11 patients who took aggressive agents for simulation of gastric ulcer and 33 patients who took pseudo-aggressive agents. Observables, conduced diagnosis of local chemical burn of mucous coat of stomach during initial 6 days after taking aggressive agents. Stages of ulcerous process, resulting from local chemical burn of mucous coat of stomach, coressponds to real gactric ulcer. Gelatin capsule using as a container for delivery of aggressive agents, melts in stomach in 5-6 minutes after taking. Independent from body position, mucous coat of greater curvature of the stomach is damaged. It is impossible to simulate duodenal bulb ulcer using the gelatine capsule or ball made of breadcrumb. The last method of delivery of aggressive agent can damage the small intestine because of uncontrollability of the place of breaking the ball.

Health effects associated with long-term occupational exposure of employees of a chlor-alkali plant to mercury.

This study aimed to evaluate possible health effects associated with long-term occupational exposure to low levels of mercury vapors. Forty-six subjects exposed to mercury and 65 healthy unexposed employees were studied. The subjects were administered a questionnaire on experienced symptoms and underwent clinical examinations as well as routine biochemical tests. Atmospheric and urinary concentrations of mercury were measured, too. Environmental concentrations of mercury were estimated to be 3.97 ± 6.28 µg/m(3) and urinary concentrations of mercury in exposed and referent groups were 34.30 ± 26.77 and 10.15 ± 3.82 µg/dm(3), respectively. Additionally, symptoms such as somatic fatigue, anorexia, loss of memory, erethism, blurred vision and teeth problems were significantly more common among exposed individuals. These observations indicate that occupational exposure to mercury vapors, even at low levels, is likely to be associated with neurological and psychological symptoms.

Modulation of cytochrome P450 and induction of DNA damage in Cyprinus carpio exposed in situ to surface water treated with chlorine or alternative disinfectants in different seasons.

Epidemiological studies have shown an association between consumption of disinfected drinking water and adverse health outcomes. The chemicals used to disinfect water react with occurring organic matter and anthropogenic contaminants in the source water, resulting in the formation of disinfection by-products (DBPs). The observations that some DBPs are carcinogenic in animal models have raised public concern over the possible adverse health effects for humans. Here, the modulation of liver cytochrome P450-linked monooxygenases (MFO) and the genotoxic effects in erythrocytes of Cyprinus carpio fish exposed in situ to surface drinking water in the presence of disinfectants, such as sodium hypochlorite (NaClO), chlorine dioxide (ClO(2)) and peracetic acid (PAA), were investigated in winter and summer. A complex induction/suppression pattern of CYP-associated MFOs in winter was observed for all disinfectants. For example, a 3.4- to 15-fold increase was recorded of the CYP2B1/2-linked dealkylation of penthoxyresorufin with NaClO (10 days) and PAA (20 days). In contrast, ClO(2) generated the most notable inactivation, the CYP2E1-supported hydroxylation of p-nitrophenol being decreased up to 71% after 10 days' treatment. In summer, the degree of modulation was modest, with the exception of CYP3A1/2 and CYP1A1 supported MFOs (62% loss after 20 days PAA). The micronucleus (MN) induction in fish circulating erythrocytes was also analysed as an endpoint of genotoxic potential in the same fish population. Significant increases of MN induction were detected at the latest sampling time on fish exposed to surface water treated with chlorinate-disinfectants, both in winter (NaClO) and summer (NaClO and ClO(2)), while no effect was observed in fish exposed to PAA-treated water. These results show that water disinfection may be responsible for harmful outcomes in terms of MFO perturbation and DNA damage; if extrapolated to humans, they ultimately offer a possible rationale for the increased urinary cancer risk recorded in regular drinking water consumers.

Mutational profiling of sporadic versus toxin-associated brain cancer formation: initial findings using loss of heterozygosity profiling.

The role of environmental and occupational toxin exposure as a cause of or contributing factor for cancer development and progression is incompletely understood. A unique signature of specific mutational change to discriminate toxin-exposed from sporadic cancer is generally sought but not often encountered. We report an approach to better understand cancer causality based on the measurement of the cumulative DNA damage (via loss of heterozygosity) over a defined genomic region (chromosome 3) that is applicable to archival, fixative-treated tissue and cytology specimens of cancer. Our method was applied to (1) a cohort of 10 brain tumor subjects (9 gliomas, 1 hemangioblastoma) with potential exposure to chlorinated solvents and (2) a control cohort of sporadic brain cancer controls (7 gliomas, 1 hemangioblastoma). We show that brain tumors arising in potentially toxin-exposed subjects bear a significantly higher level of passenger LOH mutations compared to sporadic cancer controls. The methodology utilized tissue microdissection, PCR amplification and capillary electrophoresis (fragment analysis for LOH determination, DNA sequencing for specific point mutations), and examined a panel of 15 microsatellite markers distributed along both arms of chromosome 3 that aimed at capturing passenger mutational change accrued during stages of clonal expansion of neoplastic cells. This proof-of-principle study using mutational profiling for passenger LOH mutational damage provides support for the utility of this approach and further studies in order to differentiate between genotoxin-associated versus sporadic (unexposed) cancer development.

A protocol for the evaluation of genotoxicity in bile of carp (Cyprinus carpio) exposed to lake water treated with different disinfectants.

A sensitive and rapid method to evaluate toxic and genotoxic properties of drinking water supplied from Lake Trasimeno (Umbria, Central Italy) was worked out analysing bile in Cyprinus carpio exposed for 20 d to lake water treated with 3 different disinfectants, sodium hypochlorite (NaClO), chlorine dioxide (ClO(2)) and peracetic acid (PAA). Fish were sacrificed at 0, 10 and 20 d in order to investigate the time course of these endpoints. An aliquot of bile samples was fractionated by adsorption on C(18) silica cartridges and the genotoxic potential of whole bile and of bile fractions was evaluated by the single-cell microgel-electrophoresis (comet) assay on human colonic adenocarcinoma cells (Caco-2). Bile (both whole and fractionated) from specimens exposed to the three disinfectants always showed a genotoxic activity as compared to the control group. The results of this study provide evidence that all three disinfectants cause an increase in bile genotoxicity of chronically exposed fish.

Blood pressure in relation to concentrations of PCB congeners and chlorinated pesticides.

BACKGROUND: Residents of Anniston, Alabama, live near a Monsanto plant that manufactured polychlorinated biphenyls (PCBs) from 1929 to 1971 and are relatively heavily exposed. OBJECTIVES: The goal of this study was to determine the relationship, if any, between blood pressure and levels of total serum PCBs, several PCB groups with common actions or structure, 35 individual PCB congeners, and nine chlorinated pesticides. METHODS: Linear regression analysis was used to determine the relationships between blood pressure and serum levels of the various contaminants after adjustment for age, body mass index, sex, race, smoking, and exercise in 394 Anniston residents who were not taking antihypertensive medication. RESULTS: Other than age, total serum PCB concentration was the strongest determinant of blood pressure of the covariates studied. We found the strongest associations for those PCB congeners that had multiple ortho chlorines. We found the associations over the full range of blood pressure as well as in those subjects whose blood pressure was in the normal range. The chlorinated pesticides showed no consistent relationship to blood pressure. CONCLUSIONS: In this cross-sectional study, serum concentrations of PCBs, especially those congeners with multiple ortho chlorines, were strongly associated with both systolic and diastolic blood pressure.

Effect of chlorine dioxide gas on Salmonella enterica inoculated on navel orange surfaces and its impact on the quality attributes of treated oranges.

Microorganisms, including pathogens of public health significance, have been shown to contaminate orange juice during the mechanical extraction of juice. The problem gets exacerbated when washed oranges have high initial microbial load, due to an insufficient postharvest treatment. The objective of this study was to investigate the reduction of Salmonella enterica on orange surfaces using ClO2 gas treatments to achieve a 5 log reduction, consistent with the recommendations of the U.S. Department of Agriculture-National Advisory Committee on Microbiological Criteria for Foods. A mixed culture of four Salmonella strains, isolated from previous orange juice outbreaks, was spot inoculated onto orange skin surface areas. The oranges were then treated with 0.1, 0.3, and 0.5 mg/L ClO2 gas for 2-14 minutes at 22°C and 90%-95% relative humidity. Surviving bacteria on treated areas were recovered and enumerated over treatment time on a nonselective medium, tryptic soy agar, followed by culturing onto a selective medium, xylose lysine deoxycholate agar. A >5 log reduction of Salmonella per sample of orange surface was observed with 0.1 and 0.3 mg/L ClO2 gas treatments at 14 minutes and a similar log reduction was observed at 0.5 mg/L ClO2 gas at 10 minutes. This result demonstrates that the treatment of oranges with ClO2 gas is a promising technology that could be successfully employed for the treatment of whole oranges to reduce the risk of Salmonella outbreaks in orange juice.

Short-term changes in respiratory biomarkers after swimming in a chlorinated pool.

BACKGROUND: Swimming in chlorinated pools involves exposure to disinfection by-products (DBPs) and has been associated with impaired respiratory health. OBJECTIVES: We evaluated short-term changes in several respiratory biomarkers to explore mechanisms of potential lung damage related to swimming pool exposure. METHODS: We measured lung function and biomarkers of airway inflammation [fractional exhaled nitric oxide (FeNO), eight cytokines, and vascular endothelial growth factor (VEGF) in exhaled breath condensate], oxidative stress (8-isoprostane in exhaled breath condensate), and lung permeability [surfactant protein D (SP-D) and the Clara cell secretory protein (CC16) in serum] in 48 healthy nonsmoking adults before and after they swam for 40 min in a chlorinated indoor swimming pool. We measured trihalomethanes in exhaled breath as a marker of individual exposure to DBPs. Energy expenditure during swimming, atopy, and CC16 genotype (rs3741240) were also determined. RESULTS: Median serum CC16 levels increased from 6.01 to 6.21 microg/L (average increase, 3.3%; paired Wilcoxon test p = 0.03), regardless of atopic status and CC16 genotype. This increase was explained both by energy expenditure and different markers of DBP exposure in multivariate models. FeNO was unchanged overall but tended to decrease among atopics. We found no significant changes in lung function, SP-D, 8-isoprostane, eight cytokines, or VEGF. CONCLUSIONS: We detected a slight increase in serum CC16, a marker of lung epithelium permeability, in healthy adults after they swam in an indoor chlorinated pool. Exercise and DBP exposure explained this association, without involving inflammatory mechanisms. Further research is needed to confirm the results, establish the clinical relevance of short-term serum CC16 changes, and evaluate the long-term health impacts.

The pool chlorine hypothesis and asthma among boys.

UNLABELLED: Swimming pool sanitation has largely been concerned with the microbiological quality of pool water, which is normally treated using a number of chlorine products. Recent studies have pointed to the potential hazards of chlorine by-products to the respiratory epithelium, particularly in indoor, poorly ventilated, pools. The aim of our study was to elucidate whether chronic exposure to indoor chlorinated swimming pools was associated with an increased likelihood of the development of asthma in boys. METHODS: The subjects were boys aged between 6 and 12 years. Data was collected by means of parental responses to a standardized asthma questionnaire (ISAAC: International Study of Asthma and Allergies in Childhood), supplemented with additional questions regarding frequency of attendance, number of years attendance, whether the child is a swimming team member. The questionnaire return rate was 71/% (n = 121). 23 boys were excluded on the basis that they had asthma before they started swimming (n = 97). There was a significant association between number of years a boy had been swimming and the likelihood of wheezing in the last 12 months (p = 0.009; OR = 1.351; 95% CI = 1.077-1.693) and diagnosed asthma (p = 0.046; OR = 1.299; 95% CI = 1.004-1.506). The greater the number the number of years a boy had been attending an indoor, chlorinated pool, the greater the likelihood of wheezing in the last 12 months or "had asthma". Age, parental smoking habits and being a swimming team member had no association with any of the asthma variables examined. Swimming pool attendance may be a risk factor in asthma in boys.

Intercalating, cytotoxic, antitumour activity of 8-chloro and 4-morpholinopyrimido [4',5':4,5]thieno(2,3-b)quinolines.

Circular dichroism, hydrodynamic methods, absorbance and fluorescence titration's were employed to study the interaction of 8-chloropyrimido[4',5':4,5]thieno(2,3-b)quinolin-4(3H)-one (chloro-PTQ) and 4-morpholinopyrimido[4',5':4,5]thieno(2,3-b)quinoline (morpholino-PTQ) with DNA. The association constant of chloro-PTQ and morpholino-PTQ were of the order of 10(5) and 10(6) M(-1). The fluorescence properties at ionic strength of 10mM are best fit by the neighbor exclusion model, with Ki of 0.3 x 10(4) M(-1) to 3.2 x 10(6) M(-1). CD spectra indicate that stacking of these compounds with DNA induces strong helicity in the usually disordered structure of the double strand. Viscosity experiments with sonicated rod like DNA fragments, produced a calculated length of 2.4A/bound of chloro/morpholino-PTQ molecule. The binding of chloro/morpholino-PTQ to DNA increased the melting temperature by about 1.5-7.0 degrees C. The cytotoxicity of these compounds on K-562, HL-60, Colo-205 and B16F10 melanoma are quite similar and IC(50) was in the range of 1.1-8muM. The anticancer efficacy against B16F10 melanoma has provided evidence of major anticancer activity for morpholino-PTQ. Single or multiple i.p. doses of compounds showed high level of activity against the subcutaneous (s.c.) grafted B16 melanoma with a significant increase in life span (161% and 272%). The aim of this study was to analyze the physicochemical properties of the chloro/morpholino-PTQ in an attempt to understand their superior biological activity. This research offers a new intercalation functional group to DNA targeted drug design.

Atrazine and reproductive function: mode and mechanism of action studies.

Atrazine, a chlorotriazine herbicide, is used to control annual grasses and broadleaf weeds. In this review, we summarize our laboratory's work evaluating the neuroendocrine toxicity of atrazine (and related chlorotriazines) from an historic perspective. We provide the rationale for our work as we have endeavored to determine: 1) the underlying reproductive changes leading to the development of mammary gland tumors in the atrazine-exposed female rat; 2) the cascade of physiological events that are responsible for these changes (i.e., the mode of action for mammary tumors); 3) the potential cellular mechanisms involving adverse effects of atrazine; and 4) the range of reproductive alterations associated with this pesticide.

Chlorinated river and lake water extract caused oxidative damage, DNA migration and cytotoxicity in human cells.

Consumption of chlorinated drinking water is suspected to be associated with adverse health effects, including mutations and cancer. In the present study, the genotoxic potential of water from Donghu lake, Yangtze river and Hanjiang river in Wuhan, an 8-million metropolis in China, was investigated using HepG2 cells and the alkaline version of the comet assay. It could be shown that all water extracts caused dose-dependent DNA migration in concentrations corresponding to dried extracts of 0.167-167 ml chlorinated drinking water per ml medium. To explore whether the intracellular redox status is regulated by chlorinated drinking water, we determined lipid peroxidation (LPO) and depletion of reduced glutathione (GSH). The malondialdehyde (thiobarbituric acid (TBA)-reactive aldehydes) concentration increased after chlorinated drinking water treatment of HepG2 cells in a dose-dependent manner, the GSH content decreased. The activity of lactate dehydrogenase (LDH) increased in chlorinated drinking water treated HepG2 cells indicating cytotoxicity. In accordance with former studies which dealt with in vivo and in vitro micronucleus induction the present study shows that chlorinated drinking water from polluted raw water may entail genetic risks.

Acute and chronic toxicity of chlorine dioxide (ClO2) and chlorite (ClO2-) to rainbow trout (Oncorhynchus mykiss).

GOAL, SCOPE AND BACKGROUND: Chlorite (ClO2-) is a primary decomposition product when chlorine dioxide (ClO2) is added during water treatment; therefore the toxic effects of both compounds on aquatic organisms are possible. Limited data are available concerning their toxicity to fish. The aim of this study was to investigate sensitivity of rainbow trout to acute and chronic toxicity of chlorine dioxide and chlorite, and to estimate the Maximum-Acceptable-Toxicant-Concentration (MATC) of those compounds in fish. METHODS: The acute and chronic toxicity of chlorine dioxide and chlorite to larval and adult rainbow trout was investigated in 96-hour to 20-day laboratory exposures evaluating the wide range spectrum of biological indices under semi-static conditions. RESULTS AND DISCUSSION: Median lethal concentration (96-hour LC50) values derived from the tests were: 2.2 mg/l for larvae; 8.3 mg/l for adult fish and 20-day LC50 for larvae was 1.6 mg/l of chlorine dioxide, respectively. Chlorite was found to be from 48 to 18 times less acutely toxic to larvae and adult fish, correspondingly. Both chemical compounds induced similar toxic effects in rainbow trout larvae during chronic tests (they affected cardio-respiratory and growth parameters), but chlorine dioxide had a higher toxic potency than chlorite. A significant decrease in the heart rate and respiration frequency of larvae was established. However, within an increase in exposure duration recovery of cardio-respiratory responses was seen to have occurred in larvae exposed to chlorite. Meanwhile, in larvae exposed to chlorine dioxide, a significant decrease in cardio-respiratory responses remained during all 20-day chronic bioassays. Chlorine dioxide also more strongly affected growth parameters of rainbow trout larvae at much lower test concentrations. Decreased rate of yolk-sack resorption occurred only in the tests with chlorine dioxide. CONCLUSIONS: Maximum-Acceptable-Toxicant-Concentration (MATC) of 0.21 mg/l for chlorine dioxide and of 3.3 mg/l for chlorite to fish was derived from chronic tests based on the most sensitive parameter of rainbow trout larvae (growth rate). According to substance toxicity classification accepted for Lithuanian inland waters, chlorine dioxide and chlorite can be referred to substances of 'moderate' toxicity to fish. RECOMMENDATIONS AND OUTLOOK: Due to its very reactive nature, chlorine dioxide is rapidly (in a few hours) reduced to chlorite, which is persistent also as a biocide but 16 times less toxic to fish, according to MATC. Therefore, it is much more likely that fish will be exposed to chlorite than to chlorine dioxide in natural waters. Presently accepted, the Maximum-Permitted-Concentration of total residual chlorine (TRC) in waste-water discharging into receiving waters is 0.6 mg/l. If this requirement will not be exceeded, it is unlikely that fish would be exposed to lethal or even to sublethal concentrations of chlorine dioxide or chlorite. Furthermore, chlorine dioxide does not generate toxic nitrogenous (chloramines) or carcinogenic organic residuals (trihalomethanes). All these properties make chlorine dioxide a more promising biocide than chlorine.

Modulating effects of humic acids on genotoxicity induced by water disinfectants in Cyprinus carpio.

The use of chlorinated disinfectants during drinking-water production has been shown to generate halogenated compounds as a result of interactions of humic acids with chlorine. Such chlorinated by-products have been shown to induce genotoxic effects and consumption of chlorinated drinking-water has been correlated with increased risk for cancer induction in human populations. The aim of this work was to test the potential genotoxic effects on circulating erythrocytes of the fish Cyprinus carpio exposed in vivo to well-waters disinfected with sodium hypochlorite (NaClO), chlorine dioxide (ClO2) or peracetic acid (CH3COO2H, PAA), in the absence or presence of standard humic acids (HA). The effects were measured by use of the micronucleus (MN) and the single-cell gel electrophoresis (Comet) assays at different sampling times after a 3-day exposure period. The exposure to chlorine disinfectants without the addition of HA produced a clear toxic effect. Significant cytogenetic damage (i.e. MN induction) was detected in fish populations exposed to both NaClO and ClO2 with humic acids. In the Comet assay, a significant decrease of DNA migration was observed in erythrocytes of specimens after exposure to NaClO-disinfected water without HA. No effects were observed in any other experimental condition.

The incidence of respiratory symptoms and diseases among pulp mill workers with peak exposures to ozone and other irritant gases.

OBJECTIVES: Pulp mills in Sweden started to use ozone as a bleaching agent in the early 1990s. The goal of this study was to investigate whether the incidence of selected respiratory outcomes was associated with peak exposures to ozone or other irritant gases (ie, chlorine dioxide [ClO2] or sulfur dioxide [SO2]) used in these mills. METHODS: Bleachery workers (n = 245) from three pulp mills where ozone was used participated in surveys in the mid- to late-1990s. Comparison workers (n = 80) were from two adjacent paper mills. The person-time at risk was calculated for each participant, covering the period of employment when ozone was used. Data were collected by questionnaire, and a peak exposure was defined as a self-reported exposure to an irritant gas resulting in acute respiratory symptoms. The outcomes analyzed were self-reports of physician-diagnosed asthma, attacks of wheeze, and chronic bronchitis (ie, chronic cough with phlegm). Participants also reported when the peak exposures and outcomes occurred. RESULTS: Based on proportional hazards regression (controlling for gender, age, cigarette smoking, atopy, and peak irritant exposures that occurred before follow-up), workers who reported both ozone and ClO2/SO2 peak exposures had elevated hazard ratios (HRs) for all three outcomes. Those who reported only ozone peak exposures had elevated HRs of 6.5 (95% confidence interval [CI], 1.2 to 36.3) for asthma and 3.3 (95% CI, 1.1 to 10.2) for attacks of wheeze but no increase in risk for chronic bronchitis. Workers with only ClO2/SO2 peak exposures had elevated HRs for attacks of wheeze (HR, 7.5; 95% CI, 1.9 to 29.3) and chronic bronchitis (HR, 22.9; 95% CI, 4.5 to 118.2) but not for asthma. CONCLUSIONS: These findings suggest the need for additional efforts to prevent peak exposures in pulp-bleaching operations.

Use of the Comet test and micronucleus assay on human white blood cells for in vitro assessment of genotoxicity induced by different drinking water disinfection protocols.

Surface water disinfection can lead to the formation of mutagenic/carcinogenic by-products derived from reactions with naturally occurring inorganic compounds. We investigated the feasibility and potential usefulness of an integrated approach to genotoxicity analysis of drinking water. The approach employed the Comet and micronucleus (MN) assays to evaluate the DNA and chromosomal damage produced by water extracts in human blood cells. Surface water samples from Lago Trasimeno (Italy) were collected in different seasons (July 2000, October 2000, February 2001, and June 2001), and samples were disinfected with sodium hypochloride (NaClO), chlorine dioxide (ClO(2)), or peracetic acid (PAA). Extracts of untreated and treated water were incubated with primary human leukocytes. The Comet assay revealed both strong seasonal variations and differences between samples processed by the three disinfection protocols. The three disinfectants increased the genotoxicity of the water collected in July 2000 and October 2000, with PAA producing the greatest amount of DNA damage. Extracts of raw water collected in February 2001 produced so much DNA damage that the relative genotoxic potentials of the three disinfectants could not be evaluated. No increase in MN frequency was detected in any of the samples. The multi-endpoint MN assay indicated, however, that our study samples (especially the sample collected in the February 2001) were cytotoxic. We conclude that this integrated approach to genotoxicity assessment may be useful both for the quality control of raw drinking water and to help compare the potential health risks associated with alternative disinfection processes.