Endocrine Disruptors and Thyroid Health.

A wide variety of thyroidal endocrine-disrupting chemicals (EDCs) have been identified. Exposure to known thyroidal EDCs is ubiquitous, and many likely remain unidentified. The sources of exposure include contaminated drinking water, air pollution, pesticides and agricultural chemicals, flame retardants, cleaning supplies, personal care products, food additives and packaging materials, coatings and solvents, and medical products and equipment. EDCs can affect thyroid hormone synthesis, transport, metabolism, and action in a myriad of ways. Understanding the health effects of thyroidal EDCs has been challenging because individuals may have multiple concomitant EDC exposures and many potential EDCs are not yet well characterized. Because of the importance of thyroid hormone for brain development in early life, pregnant women and young infants are particularly vulnerable to the effects of environmental thyroid disruption. The thyroidal effects of some EDCs may be exacerbated in iodine-deficient individuals, those with thyroid autoimmunity, and those with mutations in deiodinase genes. Differential exposures to EDCs may exacerbate health disparities in disadvantaged groups. High-throughput in vitro assays and in silico methods and methods that can detect the effects of relevant EDC mixtures are needed. In addition, optimal methods for detecting the effects of thyroidal EDCs on neurodevelopment need to be developed. Common sense precautions can reduce some thyroidal EDC exposures; however, regulation of manufacturing and drinking water content will ultimately be needed to protect populations.

A new 90-day drinking water study of sodium cyanide in rats to further evaluate National Toxicology Program findings and inform risk assessment.

BACKGROUND: The National Toxicology Program (NTP, 1993) reported male reproductive effects in a sodium cyanide (NaCN) drinking water study. The critical effect, decreased cauda epididymis weights, was used by U.S. Environmental Protection Agency for their hazard characterization and risk assessment of hydrogen cyanide and cyanide salts. To further investigate potential male reproductive effects, we conducted a new 90-day drinking water study. METHODS: Our study expanded evaluations of testes and thyroid. Male F344 rats received NaCN in drinking water at 0, 0 (water restricted; paired to top dose), 3, 10, 30, 100, and 300 ppm for 13 weeks, followed by 10-weeks recovery. RESULTS: Plasma thiocyanate increased dose-dependently but returned to baseline during recovery. NaCN caused neither effects on survival, body weight, food consumption, hematology, serum chemistry, urinalysis, thyroid hormones, testes or epididymides weights, sperm motility/viability, sperm morphology, or sperm production; nor clinical, ophthalmic, or histopathologic findings. Increased organ weights in thyroid/parathyroid and liver occurred at 300-ppm but were recoverable. No changes occurred in male reproductive organs. CONCLUSIONS: Absent adverse effects, the NOAEL was 300 ppm (21.66 mg/kg/day; highest dose tested). Based on organ weight increases at 300 ppm, the NOEL was 100 ppm (7.46 mg/kg/day).

Critical endpoints of PFOA and PFOS exposure for regulatory risk assessment in drinking water: Parameter choices impacting estimates of safe exposure levels.

USEPA issued drinking water interim health advisories (iHA) for PFOA and PFOS. The Agency's choice for critical effect, toxic point-of-departure (PoD), benchmark dose (BMD), pharmacokinetic (PK) model extrapolation to ingested dose, and use of uncertainty factors, resulted in the iHA for PFOS and PFOA being lowered from 70 ppt to 0.04-0.2 ppt. This review addresses key steps in the iHA derivation that influence changes in iHA values and suggests analysis and modeling changes for higher confidence in the iHA derivation, and re-evaluation of critical endpoint data for immunotoxicity and associated BMD modeling to derive a serum antibody PoD in the clinically adverse range. Movement from empirical PK modeling of ingested human dose to a platform that captures biological realism will more accurately reflect PFAS elimination, which impacts model-optimized ingested dose. The uncertainty factor (UF) for human variability should be reconsidered, as in utero and neonate exposures used to derive the iHA represent the likely susceptible populations. Although not part of the iHA derivation, cancer was considered in the drinking water maximum contaminant level goal (MCLG) technical evaluation. We discuss weaknesses in the cancer epidemiological data that require re-evaluation as the drinking water regulation process proceeds to a national standard.

Human health risk assessment of antibiotics in binary mixtures for finished drinking water.

The present study developed a new step-wise approach to estimate the potential human health risk of antibiotics in binary mixture for drinking water samples for two different sub-populations. Monte Carlo simulation based uncertainty analysis was performed to reduce uncertainty in risk assessment. Human health risk assessment studies were carried out using the acceptable daily intake (ADIs) for exposures of individual antibiotics considering point of departure (POD) and uncertainty factors (UFs). The estimated ADI values were used to estimate the predicted no effect concentrations (PNECs), at or below which no adverse human health effects are anticipated. Hazard quotient (HQ) in risk assessment was calculated as a ratio of environmental concentrations (ECs) and PNECs (EC/PNEC). The study showed that the average HQs values of individual antibiotics in adult and children were found below the acceptable limit, demonstrating no possible human health risk for both the subgroups. HIinteraction values of antibiotics in binary mixture was calculated using HQ values of antibiotics. The study observed that the estimated HIinteraction values of antibiotics in binary mixture was found to be less than 1 for both the sub populations, indicating no potential adverse effects on human health. Concentration of antibiotics was the primary contributor (>65%) to the overall variance in the uncertainty estimates for HQs of individual antibiotics in drinking water for adult and children. The co-occurrence of antibiotics in binary mixture for drinking water samples doesn't possess any possible risk on human health for the studied population.

Using disability-adjusted life years to estimate the cancer risks of low-level arsenic in drinking water.

Recent studies have shown that long-term exposure to low-level arsenic (<10 µg/L) may cause human health problems. However, the induced cancer risks and differences among multisite cancers have not been well-understood. In this study, the concentrations of low-level arsenic in drinking water in XP city, Northwest China were investigated. A health risk assessment was carried out for different age groups and exposure pathways based on Monte Carlo simulations and disability-adjusted life years (DALYs). The measured arsenic levels were in the range of 7.61-9.25 µg/L with a mean of 8.23 µg/L. For the public, the average total lifetime cancer risk was 3.87 × 10-4, and the total DALYs estimation for all age groups was 20.58 person-year. The average individual DALYs lost was 3.35 × 10-5 per person-year (ppy), which was 33.5 times the reference value (1.00 × 10-6 ppy). The mortality burden had a considerably larger contribution (97.31%) to the total disease burden, and the 60-65-year age group exhibited the largest DALYs lost. Skin cancer exhibited the largest burden of 2.15 × 10-5 ppy, followed by lung cancer (1.20 × 10-5 ppy). This study might be useful for potential strategies of risk control and management in XP drinking water.

Assessment of YAP gene polymorphisms and arsenic interaction in Mexican women with breast cancer.

The identification of gene-environment interactions related to breast cancer reveals the biological and molecular mechanisms underlying the disease and allows the distinction of women at high risk from women at lower risk, which could decrease the morbimortality of this neoplasm. The current study evaluated the association between polymorphisms rs1820453 and rs11225161 of the Yes-associated protein (YAP) gene in women with breast cancer exposed to arsenic (As) through drinking water. In total, 182 women were assessed for the frequency of YAP rs1820453 and rs11225161 polymorphisms and As urinary levels. The results demonstrated a positive and significant association between breast cancer and smoking, type of drinking water, and levels of AsIII , AsV and inorganic As (iAs) but not the YAP gene polymorphisms evaluated. In conclusion, our data showed that the source of drinking water and AsV and iAs urinary levels increased the risk for breast cancer, but no interactions between YAP gene polymorphisms and As urinary levels were found.

Compositional and health risk assessment of drinking water from health facilities of District Vehari, Pakistan.

Arsenic (As) is a potentially toxic and carcinogenic metalloid. It has gained considerable attention owing to its high ecotoxic nature. High As contamination of groundwater in scattered areas is the current status of Pakistan. A number of assessments exist for the As contamination of the drinking water in District Vehari, Pakistan. However, there is scarcity of data about As contents in drinking water of health facilities and healthcare centers in District Vehari. The current study, therefore, was carried out to assess As concentration and associated health risk in the drinking water of three health facilities (district head quarter, rural health center and basic health unit) of District Vehari. In total, 75 drinking water samples were collected and examined for As contents in addition to physicochemical characteristics such as electrical conductivity, pH, total soluble salts, chloride, carbonates, bicarbonates, fluoride, nitrate, nitrite, calcium, magnesium and iron. Results indicated that the groundwater samples are not fully fit for drinking purposes with respect to several parameters, especially the alarming levels of As. It was found that 52% of drinking water samples of Vehari have As concentration greater than WHO permissible limit (10 µg/L) and 17% have As concentration greater than Pak-EPA permissible limit (50 µg/L). The risk assessment parameters (average daily dose, hazard quotient and carcinogenic risk) showed possible carcinogenic and non-carcinogenic risks associated with ingestion of As-contaminated drinking water in the healthcare facilities. Based on the results of the present study, it is anticipated that hospitals and health centers in Vehari are in need of safe drinking water. The implementation of national/international standards for drinking water in healthcare facilities is a necessary measure to improve the services and increase local access to safe drinking water. The same may be applied to other public offices and organizations such as educational institutes and district government offices.

Probabilistic human health risk assessment of arsenic under uncertainty in drinking water sources in Jiangsu Province, China.

Concentrations of arsenic (As) in 65 drinking water sources in Jiangsu Province of China were analyzed from January 2013 to December 2015. The drinking water sources are classified into five water systems of the Yangze River, the Taihu Lake, the Huai River, the Yishusi River, and other lakes or reservoirs, which are termed as WS-A, WS-B, WS-C, WS-D, and WS-E, respectively. Health risk assessments associated with As in terms of total carcinogenic risk and total hazard index were performed for children (0-5 years), teenagers (6-17 years), and adults (≥ 18 years), respectively. Probabilistic risk assessments were obtained by applying Monte Carlo approach with consideration of uncertainty. The results indicated that in drinking water sources of WS-A, WS-C, and WS-D, maximum concentrations of As were 28 µg/L, 40 µg/L, and 17 µg/L, respectively, which were higher than 10 µg/L recommended by the World Health Organization occurred. Based on the samples investigated in this study, the mean health risks are the highest in drinking water source WS-D and lowest in WS-E for both male and female children, teenagers, and adults. For drinking water source WS-A, the health risks of male children, male teenagers, and female adults are higher than female children and female teenagers, and male adults. However, for drinking water sources WS-B, WS-C, WS-D, and WS-E, the health risks of female children, male teenagers, and female adults are higher than male children, female teenagers, and male adults. The highest health risks occurred in female children consuming drinking water from WS-D. The sensitivity analysis indicated that the concentration of As is the primary factor for carcinogenic risk of all the five water systems. The results obtained can provide meaningful information for risk managers in Jiangsu Province.

[Presence of microplastics in water and the potential impact on public health]. / Presencia de microplásticos en aguas y su potencial impacto en la salud pública.

The use of plastics has increased exponentially over recent years. Difficulties in their recycling and their low degradability result in their accumulation in the environment. Despite their great stability, they are subject to physical and chemical erosion resulting in smaller fragments. Although there is no standard definition of microplastics, the maximum limit of 5 mm has been accepted as a criterion. Plastics, in addition to the consequences on the environment, have a direct effect on living beings, either by ingestion or toxicity. They may also act as a vehicle for invasive species and adsorb other contaminants on their surface such as PCBs, PAHs or DDT. This, increases the toxic effect of their own components such as plasticizers, additives, heavy metals, etc. There is disparity in the published results regarding the presence of microplastics in both water supplies and drinking water and bottled water. There are no standard analytical methods, nor a consensus in the definition and description of microplastics that allow an appropriate comparison of results. In the absence of scientific evidence, it is necessary to study in depth the presence of microplastics in water and the potential effects on health, in order to be able to consider microplastics as a monitoring parameter in drinking water.

El uso de plásticos se ha visto incrementado de manera exponencial en los últimos años. Su difícil reciclaje y su baja capacidad de degradación tienen como consecuencia una acumulación de estos en el medio ambiente. Pese a su gran estabilidad, se ven sometidos a erosión física y química, dando lugar a fragmentos más pequeños. Aunque no hay una definición estandarizada del concepto de microplástico, se ha aceptado el límite máximo de 5 mm como criterio. Los plásticos, además de las consecuencias sobre el medio ambiente, tienen un efecto directo sobre los seres vivos, ya sea por ingestión o por toxicidad. También, pueden actuar como vehículos de especies invasoras y adsorber en su superficie otros contaminantes como los BPCs, los HAPs o el DDT, incrementando así el efecto tóxico propio debido a los componentes que poseen tales como plastificantes, aditivos, metales pesados, etc. Existe disparidad en los resultados publicados en cuanto a la presencia de microplásticos tanto en abastecimientos como en agua de consumo y embotellada. No existe una metodología normalizada de métodos analíticos, como tampoco rigor en la definición y descripción de los microplásticos que permitan la comparación de resultados. Ante la falta de evidencia científica, es necesario profundizar en el estudio sobre la presencia de estos y sus efectos potenciales en la salud, para ser considerado como un parámetro a vigilar en las aguas de consumo humano.

Chemical and microbiological risk assessment of urban river water quality in Vietnam.

The contamination and risk by nutrients (NH4+, NO2-, NO3- and PO43-), COD, BOD5, coliform and potentially toxic elements (PTEs) of As, Cd, Ni, Hg, Cu, Pb, Zn and Cr were investigated in urban river (Nhue River), Vietnam during 2010-2017. The extensive results demonstrated that concentrations of these contaminants showed significant spatial and temporal variations. The Nhue River was seriously polluted by NH4+ (0.025-11.28 mg/L), PO43- (0.17-1.72 mg/L), BOD5 (5.8-179.6 mg/L), COD (1.4-239.8 mg/L) and coliform (1540-326,470 CFU/100 mL); moderately polluted by As (0.2-131.15 µg/L) and Hg (0.11-4.1 µg/L); and slightly polluted by NO2- (0.003-0.33 mg/L) and Cd (2.1-18.2 µg/L). The concentrations of NH4+, PO43-, COD, BOD5 and coliform frequently exceeded both drinking water guidelines and irrigation water standards. Regarding PTEs, As, Cd and Hg concentrations were frequently higher than the regulatory limits. Human health risks of PTEs were evaluated by estimating hazard index (HI) and cancer risk through ingestion and dermal contacts for adults and children. The findings indicated that As was the most important pollutant causing both non-carcinogenic and carcinogenic concerns. The non-carcinogenic risks of As were higher than 1.0 at all sites for both adults (HI = 1.83-7.4) and children (HI = 2.6-10.5), while As posed significant carcinogenic risks for adults (1 × 10-4-4.96 × 10-4). A management strategy for controlling wastewater discharge and protecting human health is urgently needed.

A social-ecological analysis of drinking water risks in coastal Bangladesh.

Groundwater resources in deltaic regions are vulnerable to contamination by saline seawater, posing significant crisis for drinking water. Current policy and practice of building water supply infrastructure, without adequate hydrogeological analysis and institutional coordination are failing to provide basic drinking water services for millions of poor people in such difficult hydrogeological contexts. We apply a social-ecological systems approach to examine interdisciplinary data from hydrogeological mapping, a water infrastructure audit, 2103 household surveys, focus group discussions and interviews to evaluate the risks to drinking water security in one of 139 polders in coastal Bangladesh. We find that increasing access through public tubewells is common but insufficient to reduce drinking water risks. In response, there has been a four-fold growth in private investments in shallow tubewells with new technologies and entrepreneurial models to mitigate groundwater salinity. Despite these interventions, poor households in water-stressed environments face significant trade-offs in drinking water quality, accessibility and affordability. We argue that institutional coordination and hydrogeological monitoring at a systems level is necessary to mitigate socio-ecological risks for more equitable and efficient outcomes.

Health risk assessment of trihalomethanes in water treatment plants in Jiangsu Province, China.

Probabilistic lifetime cancer risks and non-cancer risks of trihalomethanes (THMs) through ingestion, dermal contact, and inhalation exposure in 88 drinking water treatment plants (WTPs) with raw waters from five water systems (WSs) in Jiangsu Province were analyzed and compared. Concentrations of THMs in finished water of study WTPs varied, ranging from 18.81 to 38.96 µg/L, which are lower than the maximum of 80 µg/L recommended by USEPA. The results of health risk assessment indicated that cancer risk as well as non-cancer risks of THMs in WTPs sourced from five water systems decreased in the order of WS3 > WS5 > WS2 > WS1 > WS4. The comparison among multiple exposure routes indicated that when non-boiled drinking water is consumed, ingestion has the highest exposure route, with exposure values greater than dermal contact and inhalation for WTPs with raw water from all five water systems. However, when drinking boiled water, dermal contact is the major risk source for WTPs with raw water from WS1 and WS2, instead of dermal contact, inhalation becomes the major risk source for WTPs with raw water from WS3, WS4, and WS5. In WTPs with raw water from water systems WS1, WS3, WS4, and WS5, dibromochloromethane (DBCM) in THMs has the highest contribution to cancer risk, while chloroform in THMs has the highest contribution to non-cancer risk. However, in WTPs with raw water from water system WS2, bromodichloromethane (BDCM) has the highest contribution to both cancer risk and non-cancer risk. The results also indicated that females are prone to cancer risk induced by THMs since Chinese people are accustomed to drinking boiled water. The results supply valuable information for health departments to put forward more specific and efficient policies to control water borne diseases.

Determining the presence of chemicals with suspected endocrine activity in drinking water from the Madrid region (Spain) and assessment of their estrogenic, androgenic and thyroidal activities.

Endocrine disruptors (EDs) are natural or man-made chemicals that can affect the health of organisms by interfering with their normal hormonal functions. Many of these substances can cause their effects at very low doses and, considering the key role played by the endocrine system on development, organisms in early phases of growth (foetal, childhood, puberty) are especially sensitive to the action of EDs. In addition, when combined, they can show additive, antagonistic and synergistic activities. Taking all this into account it is essential to determine the presence of this kind of compounds in drinking water. Thus the main aim of the present study was to monitor the presence of substances with suspected or known endocrine activity in drinking water of the Madrid Region (MR) (Central Spain) and determine possible estrogenic, androgenic, or thyroidal activities. Water samples were collected at different times from a number of supply points that received water from reservoirs or rivers. The sampling point with the highest concentration of the analysed substances (up to 30 compounds) was DW1 (1203 ng L-1). This sampling point receives water from a drinking water treatment plant (DWTP) that serves the population from the south of the MR with treated water from the Tajuña River. DW2 was the second point with the highest concentration of the analysed substances (1021 ng L-1). DW2 receives water from one of the reservoirs in the north of the MR. The highest daily concentrations detected corresponded to the flame retardant Tris (2-chloroethyl)phosphate (TCEP) (266.55 ng L-1) and to the nonylphenol diethoxylate (188.57 ng L-1) at points DW1 and DW4, respectively, both of which are supplied with treated river water. None of the water samples exhibited androgenic, oestrogenic, or thyroidal activities in in vitro assays based on cells stably transfected with the receptors of interest and luciferase as reporter gene. These results demonstrate that water quality in the MR is high and does not present a health risk for the population, although the concentrations of some substances justify the need for local authorities to continually monitor the presence of these contaminants in order to implement any corrective measures if necessary.

Association between salinity and hospital admission for hypertension: an ecological case-control study in the Mekong Delta Region in Vietnam.

Background: Drinking water in the Mekong Delta Region (MDR) is highly vulnerable to salinity intrusion and this problem is expected to increase with the projected climate change and sea level rise. Despite this, research on health effects of saline contaminated water is scarce in this region. This study examines the risk of hospital admission for hypertension in salinity-affected areas of the MDR. Methods: Cases and controls were obtained from national/provincial hospital admission records for 2013. The cases were adult patients whom hypertension (ICD10-code: I10-I15) was primary diagnosis for admission. Of the 13 provinces in the MDR, we identified seven as 'salinity exposed' and the remaining as 'non-exposed' areas. A multi-level logistic regression model was used to examine the association between salinity exposure and hypertension outcome. Results: Of the total 573 650 hospital admissions, 22 382 (~3.9%) were hypertensive cases. The multi-level logistic model combining both individual and ecological factors showed a 9% increase in risk (95% CI: 3-14%) of hypertension admission among individuals in exposed areas compared to those in non-exposed areas. Conclusion: In order to develop and promote appropriate adaptation strategies, further research is recommended to identify the salt exposure pathways and consumption behaviours in the salinity exposed areas.

Changes in water manganese levels and longitudinal assessment of intellectual function in children exposed through drinking water.

BACKGROUND: Manganese is commonly found in water but potential neurotoxic effects from exposure through drinking water are poorly understood. We previously reported a cross-sectional study showing that drinking water Mn concentration was associated with lower IQ in children aged 6 to 13 years. OBJECTIVE: For this follow-up study, we aimed to re-assess the relation between exposure to Mn from drinking water and IQ at adolescence. In addition, we aimed to examine whether changes in drinking water Mn concentration was associated with changes in IQ scores. METHODS: From the 380 children enrolled in the baseline study, 287 participated to this follow-up study conducted in average 4.4 years after. Mn concentration was measured in home tap water and children's hair. The relationships between these Mn exposure indicators and IQ scores (Weschsler Abbreviated Scale of Intelligence) at follow-up were assessed with linear regression analysis, adjusting for potential confounders. Intra-individual differences in IQ scores between the two examinations were compared for children whose Mn concentration in water remained stable between examinations, increased or decreased. RESULTS: The mean age at follow-up was 13.7 years (range, 10.5 to 18.0 years). Geometric mean of Mn concentration in water at follow-up was 14.5µg/L. Higher Mn concentration in water measured at follow-up was associated with lower Performance IQ in girls (ß for a 10-fold increase=-2.8, 95% confidence intervals [CI] -4.8 to -0.8) and higher Performance IQ in boys (ß=3.9, 95% CI 1.4 to 6.4). IQ scores were not significantly associated with Mn concentration in hair, although similar trends as for concentration in water were observed. For children whose Mn concentration in water increased between baseline and follow-up, Performance IQ scores decreased significantly (intra-individual difference, -2.4 points). CONCLUSION: Higher levels of Mn in drinking water were associated with lower Performance IQ in girls, whereas the opposite was observed in boys. These findings suggest long-term exposure to Mn through drinking water is associated differently with cognition in boys and girls.

A study of DNA damage in buccal cells of consumers of well- and/or tap-water using the comet assay: Assessment of occupational exposure to genotoxicants.

Because of concerns that natural aquifers in the region of Todos Santos (Baja California Sur, Mexico) might be contaminated by organochlorine pesticides and heavy metals, a case-control study was conducted among consumers and non-consumers of well- and/or tap-water to determine risks to human health. This study was based on a genotoxic evaluation of buccal cells using the Comet assay technique. Levels of DNA damage in the consumers group were significantly higher than those of the control group. However, occupational exposure to genotoxicants showed to be the critical factor rather than water consumption. Taking into account the professions of well- and/or tap-water consumers, agricultural workers exposed directly (those who fumigated) or indirectly (those not involved in fumigating) to agrochemicals showed greater genetic damage than controls. This difference persisted even when age, and whether the person smoked or consumed alcoholic drinks were considered. These factors were not associated with the level of genetic damage observed. Chemical analyses of organochlorine pesticides and heavy metals were carried out to evaluate the water quality of wells, faucets, and surface water of canals consumed by the population and/or used for irrigation. High concentrations of α and ß endosulfan were detected in water of surface canals. Although our inventory of agrochemicals employed in the region showed the use of products considered carcinogenic and/or mutagenic, they were not detected by the analytical techniques used. Heavy metals (arsenic, mercury, and lead) were detected in water of some wells used for irrigation and human consumption. Environ. Mol. Mutagen. 58:619-627, 2017. © 2017 Wiley Periodicals, Inc.

Management of Risks From Water and Ice From Ice Machines for the Very Immunocompromised Host: A Process Improvement Project Prompted by an Outbreak of Rapidly Growing Mycobacteria on a Pediatric Hematopoietic Stem Cell Transplant (Hsct) Unit.

BACKGROUND In 2011, pediatric hematopoietic stem cell transplant (HSCT) patients were moved from an older hospital to a new children's hospital. To minimize bacterial growth in the new hospital's water during construction, the plumbing system was flushed and disinfected before occupancy. However, 6 months after occupancy, an increased incidence of rapidly growing mycobacteria (RGM) was detected in clinical cultures. Over 10 months, 15 pediatric HSCT patients were infected, while no pediatric HSCT patients had been infected in the preceding 12 months. OBJECTIVE To determine the cause of the outbreak and to interrupt patient acquisition of RGM. METHODS Water samples were collected from water entering the hospital and from drinking water and ice machines (DWIMs) from the old and new hospitals. Total heterotrophic plate counts (HPCs, CFU/mL) of water were undertaken, and select isolates were identified as RGM. RESULTS The cause of the outbreak was increased bacterial levels in the water (including RGM) in the DWIMs in the new (2011) hospital. Tests revealed higher HPCs in drinking water and ice from the DWIMs in the new hospital than in the DWIMs in the old hospital. Ultimately, HPCs were reduced by several different interventions. CONCLUSION In response to an RGM outbreak, HSCT patients were banned from ingesting DWIM ice and water and bottled water was provided. Since this interverntion 4 years ago, no additional RGM isolates have been identified in HSCT patient cultures. Our measures to reduce HPCs to goal levels in drinking water from DWIMs were successful, but the HPCs for ice have not consistently reached the goal of <500 CFU/mL. Infect Control Hosp Epidemiol 2017;38:792-800.

Risk assessment of fluoride exposure in drinking water of Tunisia.

The presence of fluoride in drinking water is known to reduce dental cavities among consumers, but an excessive intake of this anion might leads to dental and skeletal fluorosis. This study reports a complete survey of the fluoridated tap water taken from 100 water consumption points in Tunisia. The fluoride concentrations in tap water were between 0 and 2.4 mg L-1. Risk assessment of Fluoride exposure was assessed depending on the age of consumers using a four-step method: hazard identification, toxicity reference values selection (TRVs), daily exposure assessment, and risk characterization. Our findings suggest that approximately 75% of the Tunisian population is at risk for dental decay, 25% have a potential dental fluorosis risk, and 20% might have a skeletal fluorosis risk according to the limits of fluoride in drinking water recommended by WHO. More investigations are recommended to assess the exposure risk of fluoride in other sources of drinking water such as bottled water.