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Microorganisms populating the water-related indoor biome.
Novak Babič, M, Gostinčar, C, Gunde-Cimerman, N
Applied microbiology and biotechnology. 2020;(15):6443-6462
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Abstract
Modernisation of our households created novel opportunities for microbial growth and thus changed the array of microorganisms we come in contact with. While many studies have investigated microorganisms in the air and dust, tap water, another major input of microbial propagules, has received far less attention. The quality of drinking water in developed world is strictly regulated to prevent immediate danger to human health. However, fungi, algae, protists and bacteria of less immediate concern are usually not screened for. These organisms can thus use water as a vector of transmission into the households, especially if they are resistant to various water treatment procedures. Good tolerance of unfavourable abiotic conditions is also important for survival once microbes enter the household. Limitation of water availability, high or low temperatures, application of antimicrobial chemicals and other measures are taken to prevent indoor microbial overgrowth. These conditions, together with a large number of novel chemicals in our homes, shape the diversity and abundance of indoor microbiota through constant selection of the most resilient species, resulting in a substantial overlap in diversity of indoor and natural extreme environments. At least in fungi, extremotolerance has been linked to human pathogenicity, explaining why many species found in novel indoor habitats (such as dishwasher) are notable opportunistic pathogens. As a result, microorganisms that often enter our households with water and are then enriched in novel indoor habitats might have a hitherto underestimated impact on the well-being of the increasingly indoor-bound human population. KEY POINTS Domestic environment harbours a large diversity of microorganisms. Microbiota of water-related indoor habitats mainly originates from tap water. Bathrooms, kitchens and household appliances select for polyextremotolerant species. Many household-related microorganisms are human opportunistic pathogens.
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Microcystin Incidence in the Drinking Water of Mozambique: Challenges for Public Health Protection.
Tamele, IJ, Vasconcelos, V
Toxins. 2020;(6)
Abstract
Microcystins (MCs) are cyanotoxins produced mainly by freshwater cyanobacteria, which constitute a threat to public health due to their negative effects on humans, such as gastroenteritis and related diseases, including death. In Mozambique, where only 50% of the people have access to safe drinking water, this hepatotoxin is not monitored, and consequently, the population may be exposed to MCs. The few studies done in Maputo and Gaza provinces indicated the occurrence of MC-LR, -YR, and -RR at a concentration ranging from 6.83 to 7.78 µg·L-1, which are very high, around 7 times above than the maximum limit (1 µg·L-1) recommended by WHO. The potential MCs-producing in the studied sites are mainly Microcystis species. These data from Mozambique and from surrounding countries (South Africa, Lesotho, Botswana, Malawi, Zambia, and Tanzania) evidence the need to implement an operational monitoring program of MCs in order to reduce or avoid the possible cases of intoxications since the drinking water quality control tests recommended by the Ministry of Health do not include an MC test. To date, no data of water poisoning episodes recorded were associated with MCs presence in the water. However, this might be underestimated due to a lack of monitoring facilities and/or a lack of public health staff trained for recognizing symptoms of MCs intoxication since the presence of high MCs concentration was reported in Maputo and Gaza provinces.
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Evaluation of different culture media for detection and quantification of H. pylori in environmental and clinical samples.
Hortelano, I, Moreno, Y, Vesga, FJ, Ferrús, MA
International microbiology : the official journal of the Spanish Society for Microbiology. 2020;(4):481-487
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Abstract
The objective of the present study was to establish the most suitable culture medium for the isolation of H. pylori from environmental and clinical samples. Ten different culture media were compared and evaluated. Four of them had been previously described and were modified in this study. The rest of the media were designed de novo. Three different matrices, tap water, wastewater, and feces, were inoculated with serial dilutions of H. pylori NCTC 11637 strain at a final concentration of 104 and 103 CFU/ml and the recovery rates were calculated. From inoculated tap water and wastewater samples, H. pylori colonies were recovered from four out of the analyzed culture media. When fecal samples were analyzed, the isolation of the pathogen under study was only possible from two culture media. Different optimal media were observed for each type of sample, even for wastewater and stool samples. Nevertheless, our results indicated that the combination of Dent Agar with polymyxin B sulfate did not inhibit the growth of H. pylori and was highly selective for its recovery, regardless of the sample origin. Thus, we propose the use of this medium as a diagnostic tool for the isolation of H. pylori from environmental and clinical samples, as well as for epidemiological studies.
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An evaluation of the USEPA Proposed Approaches for applying a biologically based dose-response model in a risk assessment for perchlorate in drinking water.
Clewell, HJ, Gentry, PR, Hack, CE, Greene, T, Clewell, RA
Regulatory toxicology and pharmacology : RTP. 2019;:237-252
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Abstract
The United States Environmental Protection Agency's (USEPA) 2017 report, "Draft Report: Proposed Approaches to Inform the Derivation of a Maximum Contaminant Level Goal for Perchlorate in Drinking Water", proposes novel approaches for deriving a Maximum Contaminant Level Goal (MCLG) for perchlorate using a biologically-based dose-response (BBDR) model. The USEPA (2017) BBDR model extends previously peer-reviewed perchlorate models to describe the relationship between perchlorate exposure and thyroid hormone levels during early pregnancy. Our evaluation focuses on two key elements of the USEPA (2017) report: the plausibility of BBDR model revisions to describe control of thyroid hormone production in early pregnancy and the basis for linking BBDR model results to neurodevelopmental outcomes. While the USEPA (2017) BBDR model represents a valuable research tool, the lack of supporting data for many of the model assumptions and parameters calls into question the fitness of the extended BBDR model to support quantitative analyses for regulatory decisions on perchlorate in drinking water. Until more data can be developed to address uncertainties in the current BBDR model, USEPA should continue to rely on the RfD recommended by the NAS (USEPA, 2005) when considering further regulatory action.
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Avoiding Alzheimer's disease: The important causative role of divalent copper ingestion.
Brewer, GJ
Experimental biology and medicine (Maywood, N.J.). 2019;(2):114-119
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Abstract
The work described in this review is very important to scientists working on Alzheimer's disease (AD) because it reveals a cause for the explosive epidemic of this disease. It is also important to the public because it provides a method to avoid this newly revealed cause, and thereby avoid AD. The field is advanced because this review reveals new information about the mechanism of AD pathogenesis, namely copper, and specifically divalent copper, toxicity is important. New information about divalent copper toxicity in the brain affecting cognition is revealed. The field is impacted strongly because, in view of the frustrations that have occurred in treatment developed, now most AD can be prevented. This means the suffering of the patient, the prolonged and difficult care required by caregivers, and the enormous expenditures for this one disease, can now be avoided.
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Nontuberculous mycobacteria in drinking water systems - the challenges of characterization and risk mitigation.
Dowdell, K, Haig, SJ, Caverly, LJ, Shen, Y, LiPuma, JJ, Raskin, L
Current opinion in biotechnology. 2019;:127-136
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Abstract
Nontuberculous mycobacteria (NTM) pulmonary infections are a growing concern worldwide, with a disproportionate incidence in persons with pre-existing health conditions. NTM have frequently been found in municipally-treated drinking water and building plumbing, leading to the hypothesis that an important source of NTM exposure is drinking water. The identification and quantification of NTM in environmental samples are complicated by genetic variability among NTM species, making it challenging to determine if clinically relevant NTM are present. Additionally, their unique cellular features and lifestyles make NTM and their nucleic acids difficult to recover. This review highlights a recent work focused on quantification and characterization of NTM and on understanding the influence of source water, treatment plants, distribution systems, and building plumbing on the abundance of NTM in drinking water.
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A review of the pathways of human exposure to poly- and perfluoroalkyl substances (PFASs) and present understanding of health effects.
Sunderland, EM, Hu, XC, Dassuncao, C, Tokranov, AK, Wagner, CC, Allen, JG
Journal of exposure science & environmental epidemiology. 2019;(2):131-147
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Abstract
Here, we review present understanding of sources and trends in human exposure to poly- and perfluoroalkyl substances (PFASs) and epidemiologic evidence for impacts on cancer, immune function, metabolic outcomes, and neurodevelopment. More than 4000 PFASs have been manufactured by humans and hundreds have been detected in environmental samples. Direct exposures due to use in products can be quickly phased out by shifts in chemical production but exposures driven by PFAS accumulation in the ocean and marine food chains and contamination of groundwater persist over long timescales. Serum concentrations of legacy PFASs in humans are declining globally but total exposures to newer PFASs and precursor compounds have not been well characterized. Human exposures to legacy PFASs from seafood and drinking water are stable or increasing in many regions, suggesting observed declines reflect phase-outs in legacy PFAS use in consumer products. Many regions globally are continuing to discover PFAS contaminated sites from aqueous film forming foam (AFFF) use, particularly next to airports and military bases. Exposures from food packaging and indoor environments are uncertain due to a rapidly changing chemical landscape where legacy PFASs have been replaced by diverse precursors and custom molecules that are difficult to detect. Multiple studies find significant associations between PFAS exposure and adverse immune outcomes in children. Dyslipidemia is the strongest metabolic outcome associated with PFAS exposure. Evidence for cancer is limited to manufacturing locations with extremely high exposures and insufficient data are available to characterize impacts of PFAS exposures on neurodevelopment. Preliminary evidence suggests significant health effects associated with exposures to emerging PFASs. Lessons learned from legacy PFASs indicate that limited data should not be used as a justification to delay risk mitigation actions for replacement PFASs.
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On the Use of Hair Analysis for Assessing Arsenic Intoxication.
Katz, SA
International journal of environmental research and public health. 2019;(6)
Abstract
Correlations between the concentrations of arsenic in scalp hair and in drinking water as well as in blood and/or urine have been reported. These correlations clearly show exposure⁻absorption⁻excretion relationships. In addition, arsenic metabolites such as monomethylarsonic acid and dimethylarsinic acid have been identified and quantified in these tissues and fluids, leaving little doubt that elevated levels of arsenic in the hair can reflect systemic arsenic intoxication. Consequently, hair analysis has potential merit as a screening procedure for poisoning by arsenic. However, questions regarding the exogenous versus the endogenous deposition of arsenic in the hair, and uncertainties about the normal level of arsenic in the hair remain unresolved. Pending their resolution, the determination of arsenic in hair should remain a screening tool, and clinical signs and symptoms should be employed to complete the diagnosis of arsenic poisoning.
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Protozoan Parasites in Drinking Water: A System Approach for Improved Water, Sanitation and Hygiene in Developing Countries.
Omarova, A, Tussupova, K, Berndtsson, R, Kalishev, M, Sharapatova, K
International journal of environmental research and public health. 2018;(3)
Abstract
Improved water, sanitation and hygiene (WASH) are significant in preventing diarrhea morbidity and mortality caused by protozoa in low- and middle-income countries. Due to the intimate and complex relationships between the different WASH components, it is often necessary to improve not just one but all of these components to have sustainable results. The objective of this paper was to review the current state of WASH-related health problems caused by parasitic protozoa by: giving an overview and classification of protozoa and their effect on people's health, discussing different ways to improve accessibility to safe drinking water, sanitation services and personal hygiene behavior; and suggesting an institutional approach to ensure improved WASH. The findings indicate that Giardia and Cryptosporidium are more often identified during waterborne or water-washed outbreaks and they are less sensitive than most of the bacteria and viruses to conventional drinking water and wastewater treatment methods. There are various institutions of control and prevention of water-related diseases caused by protozoa in developed countries. Unfortunately, the developing regions do not have comparable systems. Consequently, the institutional and systems approach to WASH is necessary in these countries.
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Potable Water Reuse: What Are the Microbiological Risks?
Nappier, SP, Soller, JA, Eftim, SE
Current environmental health reports. 2018;(2):283-292
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Abstract
PURPOSE OF REVIEW With the increasing interest in recycling water for potable reuse purposes, it is important to understand the microbial risks associated with potable reuse. This review focuses on potable reuse systems that use high-level treatment and de facto reuse scenarios that include a quantifiable wastewater effluent component. RECENT FINDINGS In this article, we summarize the published human health studies related to potable reuse, including both epidemiology studies and quantitative microbial risk assessments (QMRA). Overall, there have been relatively few health-based studies evaluating the microbial risks associated with potable reuse. Several microbial risk assessments focused on risks associated with unplanned (or de facto) reuse, while others evaluated planned potable reuse, such as indirect potable reuse (IPR) or direct potable reuse (DPR). The reported QMRA-based risks for planned potable reuse varied substantially, indicating there is a need for risk assessors to use consistent input parameters and transparent assumptions, so that risk results are easily translated across studies. However, the current results overall indicate that predicted risks associated with planned potable reuse scenarios may be lower than those for de facto reuse scenarios. Overall, there is a clear need to carefully consider water treatment train choices when wastewater is a component of the drinking water supply (whether de facto, IPR, or DPR). More data from full-scale water treatment facilities would be helpful to quantify levels of viruses in raw sewage and reductions across unit treatment processes for both culturable and molecular detection methods.