Fluoride in drinking water: A survey of expert opinions

In recent years, public debate over the standard setting process related to fluoride in drinking water and the fiuoridation of water supplies has been steeped in much controversy. Discussion of such issues has been con strained by the limited consideration of options relevant to particular problems. To examine the responses to specific issues, we presented an analysis of the problem of excessive fluoride in drinking water to a group of 120 experts. Ninety-seven of the 120 responded to a detailed mail questionnaire distributed as part of a larger exploratory survey. Definite patterns in preferences were noted with certain aspects of the problem, although in some cases significant differences were found due to such factors as the institutional affiliation, residential status, and the length of professional experience of the participants. In general, our experts preferred immediate corrective action over extensive further research into the reduction of scientific uncertainties; were willing to take personal action to obtain fluoride-free water rather than wait for official action; preferred the supplier to fluoridate the supplies, if needed; and favoured a strong local control of such issues with consumers of public water systems and private well owners shouldering much of the financial responsibility. Preliminary results from such exploratory surveys can lead to insightful research hypotheses for further testing. Verification of such hypotheses by consumers, from areas with excessive fluoride in drinking water, is a valuable area for future research.     

Naturally occurring radionuclides in drinking water: An exercise in risk benefit analysis

The scientific background information describing the occurrence, measurement, health effects, treatment technology, risk assessment and economic consequences of the presence of naturally occurring radionuclides in drinking water are described for 60,000 public drinking water supplies. The relevant data for the occurrence of radium, uranium and radon in drinking water supplies are discussed and analysed. Radon is of importance because it is released in the process of taking showers and baths and in washing dishes and clothes. Its progeny is then inhaled, leading to the risk of lung cancer. Radium and uranium can both cause bone cancer. The range of average occurrence of natural radioactivity in drinking water is as follows:²²⁶Ra, 0.3 to 0.8 pCi L^–1;²²⁸Ra, 0.4 to 1.0 pCi L^–1; uranium, 0.3 to 2.0 pCi L^–1 and²²²Rn, 500 to 600 pCi L^–1. The estimated lifetime risks due to the mean groundwater concentrations of naturally occurring radionuclides are:²²⁶Ra and^228Ra, 1.0 10^–5; uranium, 2.0 × 10^–6 and radon, 4.0 × 10^–4. The cost to reduce total radium levels to 5.0 pCi L^–1 is about $9 million. An equivalent expenditure would be required to reduce radon levels to about 4,000 pCi L^–1, or uranium levels to about 100 pCi L^–1. The problem of maximizing the total mortality and the reduction per unit dollar outlay per unit dollar cost for the uranium/radon case is examined.The thoughts and ideas expressed in this paper are those of the authors and are not necessarily those of the US Environmental Protection Agency.This paper is published as a contribution to discussion on this problem and not as a paper providing new research data.     

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running. Effects of lead on exploratory behavior and running speed in the shrew, Blarina brevicauda (Insectivora)

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running speed in the short-tailed shrew, Blarina brevicauda. Shrews from the experimental group received 25 mg/kg/day of lead acetate in their drinking water for a period of 90 days. Control subjects received sodium acetate. Exploratory behavior was determined using a computerized activity chamber where movements of test subjects broke infrared beams projected onto the floor of the apparatus. Time spent (sec) in exploration was recorded over eight 6-min intervals. Running speed (km/hr) was measured in a microprocessor-controlled rectangular racetrack fitted with photocell timers. With respect to time spent in exploration, there were significant differences between lead-exposed (20.5-23.9 sec per 6-min testing session) and control subjects (6.8-8.1 sec) after the sixth testing interval in the activity chamber. With respect to maximal running speed, control subjects ran significantly faster (mean: 14.8 km/hr) than their lead-exposed counterparts (5.83 km/hr). Lead-exposed animals exhibited hyperactivity and increased random locomotor movements. They would frequently bump into the walls and their movements were more random. Controls typically ran along the racetrack in a straight line. These results represent the first data for the effects of lead exposure on exploratory behavior and running speed for shrews.     

Non-carcinogenic effects of inorganic arsenic

This review will focus primarily on ohe effects of the inorganic arsenicals (arsenate and arsenite forms) that are present in drinking water. They are acutely toxic to both humans and animals, an effect that may be related to their bioavailibility. In humans, arsenicals have been reported to cause dermatitis and mucous membrane irritation upon exposure. They have also been reported to cause skin lesions and peripheral neurotoxicity in smelter workers and in patients treated with Fowler's Solution. When humans are exposed to arsenic in drinking water, effects such as hyperkeratosis, electromyographic abnormalities and vascular effects have been reported. In experimental animals, arsenic has been demonstrated to affect the liver and kidneys. In mice, arsenic has also been reported to decrease the animal's resistance to certain viral infections. The arsenite (+3) and arsenate (+5) forms have different modes of action. Arsenite binds to sulphhydryl groups and has been reported to inhibit over 100 different enzymes, while the arsenate can substitute for phosphate in various high energy intermediates, resulting in arsenolysis. In addition, when arsenate is reduced to arsenite in the body, it can also cause toxicity as that species.     

Malaysian households' drinking water practices: A case study

Malaysia has abundant water resources and adequate rainfall and yet the nation has water shortages and water quality problem. Various measures have been taken by the government to address water issues but, in spite of these, quantity and quality of drinking water is still one of the main concerns of Malaysian consumers today. An exploratory study was undertaken to determine the level of awareness of respondents on water issues, assess their perception on drinking water quality, and identify measures undertaken by households to improve drinking water quality and to determine sustainable water practices. A cross-sectional research design, utilizing a survey was conducted among urban residents of Seremban town. Data showed that each household had a mean of five members, with an average household income of RM3788.00 (US$1000). The respondents were Chinese (70%), Indian (23%) and Malay (7%). The majority of respondents rated the quality of water supplied to their house as poor (70%), while 16% rated it very poor. The respondents indicated that colour, odour and taste were the main problems with their tap water. Due to the poor tap water quality perceived by respondents, most took additional measures to improve its quality. Most (85%) purchased domestic water filters, 41% boiled water and 17% bought bottled water. The reasons for purchasing water were: concern for health, perception of poor tap water quality, and increasing water contamination and pollution in the country. Almost a quarter of respondents that had water filters mentioned the convenience because they did not have to boil water. Sustainable use of water by respondents was moderate, with a mean of 2.9 on a scale of 1 (never) to 4 (all the time). Some aspects of conservation, such as the promptness of repairing leaking pipes, planning activities to conserve water, and method of car washing could be improved. Advantages and limitations of different water technologies are discussed. Sustainable water practices are also proposed.     

Development and application of innovative technologies for drinking water quality assurance in China

The continuously deteriorating quality of source water is threatening the safety of drinking water in China. Various efforts have been made to update water treatment processes to decrease the pollution problems of drinking water, such as protection of drinking water sources, enhancement of conventional treatment processes, and development of new or advanced treatment technologies. This paper reviews a variety of protection and remediation methods for drinking water sources, development and application of drinking water treatment technologies, new technologies for special pollutants removal from groundwater, and the latest research progress on water distribution systems in China.     

Seeing,believing, and behaving: Heterogeneous effects of an information intervention on household water treatment

Providing information about environmental health risks only sometimes induces protective action. This raises questions about whether and how risk information is understood and acted upon, and how responses vary across contexts. To characterize such variation, we stratified a randomized experiment related to household water quality across two periurban areas in Cambodia. When we showed specific evidence of water contamination to lower-SES households who were initially more optimistic about water safety, they altered their beliefs about health risk and increased their demand for a treatment product. However, demand for the treatment product among higher and initially more pessimistic SES households did not change significantly. These findings highlight the importance of better understanding heterogeneity in the specific drivers of responses to health risk information.     

What have we known so far about microplastics in drinking water treatment? A timely review

• 23 available research articles on MPs in drinking water treatment are reviewed. • The effects of treatment conditions and MP properties on MP removal are discussed. • DWTPs with more steps generally are more effective in removing MPs. • Smaller MPs (e.g.,<10 μm) are more challenging in drinking water treatment. Microplastics (MPs) have been widely detected in drinking water sources and tap water, raising the concern of the effectiveness of drinking water treatment plants (DWTPs) in protecting the public from exposure to MPs through drinking water. We collected and analyzed the available research articles up to August 2021 on MPs in drinking water treatment (DWT), including laboratory- and full-scale studies. This article summarizes the major MP compositions (materials, sizes, shapes, and concentrations) in drinking water sources, and critically reviews the removal efficiency and impacts of MPs in various drinking water treatment processes. The discussed drinking water treatment processes include coagulation-flocculation (CF), membrane filtration, sand filtration, and granular activated carbon (GAC) filtration. Current DWT processes that are purposed for particle removal are generally effective in reducing MPs in water. Various influential factors to MP removal are discussed, such as coagulant type and dose, MP material, shape and size, and water quality. It is anticipated that better MP removal can be achieved by optimizing the treatment conditions. Moreover, the article framed the major challenges and future research directions on MPs and nanoplastics (NPs) in DWT.     

Aliphatic and aromatic halocarbons as potential mutagens in drinking water

Chlorinated phenols are either products of industrial chemical processes or the result of chlorination of drinking water. Often, the formation of chlorinated phenols is based upon naturally occurring phenol. The following chlorinated phenols have been selected for testing in the Ames‐test for their mutagenic activity: 3‐chlorophenol, 4‐chlorophenol, 2,3,6‐, 2,4,5‐, 2,4,6‐trichlorophenol, 4‐chloro‐2‐methylphenol and 4‐chloro‐3‐methylchlorophenol. The tester strains TA97, TA98, TA100 and TA104 were employed. All tested compounds produced mutagenic activity at least in one tester strain. The highest numbers of revertants were detected for 2,3,6‐ and 2,4,6‐trichlorophenol. But in contrast to the other substances, these two induced only frameshift mutations in presence of a metabolizing system. The evidence of their presence in drinking water and of their mutagenic activity makes them to a potential health hazard.     

Photocatalytic degradation of ciprofloxacin in aqueous media: a short review

The frequent detection of antibiotics such as ciprofloxacin in surface and drinking waters around the world has attracted concern from various researchers. Such presence is an indication that the decontamination of water polluted by antibiotics is beyond the conventional treatment methods. However, among the different treatment methods that have been developed in the area of water purification, heterogeneous photocatalysis using semiconductor as a mediator has been rated as an efficient and a green wastewater treatment method. This is because, the process is effective in degrading and mineralizing organic pollutants, using UV or visible light. The present review paper covers a brief survey over a range of publications in the last decade, involving photocatalytic materials that have been employed in the purification of water contaminated by ciprofloxacin.     

Presence,dissemination and removal of antibiotic resistant bacteria and antibiotic resistance genes in urban drinking water system: A review

Reviewed the change of ARGs and ARB in full-scale urban drinking water systems. Conventional processes are more promising than BAC process in ARGs removal. Mechanisms of ARGs enrichment and spread in BAC filter and DWDSs are discussed. Raise the need of future research on ARGs and ARB change in building plumbing systems. Antibiotic resistance in aquatic environment has become an important pollution problem worldwide. In recent years, much attention was paid to antibiotic resistance in urban drinking water systems due to its close relationship with the biosafety of drinking water. This review was focused on the mechanisms of antibiotic resistance, as well as the presence, dissemination and removal of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the urban drinking water system. First, the presence of ARB and ARGs in the drinking water source was discussed. The variation of concentration of ARGs and ARB during coagulation, sedimentation and filtration process were provided subsequently, in which filtration was proved to be a promising technology to remove ARGs. However, biological activated carbon (BAC) process and drinking water distribution systems (DWDSs) could be incubators which promote the antibiotic resistance, due to the enrichment of ARGs and ARB in the biofilms attached to the active carbon and pipe wall. Besides, as for disinfection process, mechanisms of the inactivation of ARB and the promotion of conjugative transfer of ARGs under chlorine, ozone and UV disinfection were described in detail. Here we provide some theoretical support for future researches which aim at antibiotic resistance controlling in drinking water.     

Radon in soil gas and its relationship with some major faults of SW England

The south-west of England was designated by the National Radiological Protection Board (NRPB) as the first ‘Radon Affected Area’, as over 1% of the housing stock is estimated to have an indoor radon concentration in excess of the 200 Bq m⁻³ Action Level. The situation is even worse for houses situated above uraniferous granite intrusions, where over 30% are thought to be above the Action Level. The aim of this study is to investigate the relationship between the level of radon in soil gas and the local geology. Particularly high radon levels were measured along major fault zones. This could be explained by: increased rate of migration of the radon due to the permeable fault, the presence of radium or radon-bearing ground water within the fault, or secondary uranium mineralisation. Seasonal variations are also considered.     

Chronic kidney disease in two coastal districts of Andhra Pradesh, India: role of drinking water

Chronic kidney disease (CKD) has been reported in a few coastal regions of Srikakulam district and Chimakurthy mandal (~30–40 km away from the coast) in the Prakasham district of Andhra Pradesh, India. Some medical experts and the local population have apprehensions that the drinking water is the sole reason for this disease in these areas. As the source of drinking water for these two regions is only groundwater, major ions and trace elements were measured on waters from different sources to identify the causative element(s), if any. Comparison of hydrochemical data of both the areas indicates that groundwater in Srikakulam coastal region is less mineralized than that of the Prakasham region, which may be due to geological, hydrological and climatic reasons. However, the concentrations of various inorganic chemicals are within the permissible limits of drinking water. Hence, for the inorganic chemicals to cause ill health, including CKD, is unlikely or is ruled out in the study areas.     

饮水除氟剂的应用

本文对国内饮水除氟剂的研究和应用现状进行了综述，对常用絮凝剂和滤料的除氟性能、适宜条件及应用情况进行了简要比较，同时对近期研制和生产的新除氟剂，如ＣＦ－１，ＰＣ８５－３，６２１０，以及新型除氟滤料，如ＧＴ，ＳＢＣ，ＣＦ型微型过滤管、蛇纹石、ＵＲ－３７００螯合树脂等的除氟效果进行了讨论。     

Climate-induced reaction norms for life-history traits in pythons

Climate change modelers predict increasingly frequent "extreme events," so it is critical to quantify whether organismal responses (such as reproductive output) measured over the range of usual climatic conditions can predict responses under more extreme conditions. In a 20-year field study on water pythons (Liasis fuscus), we quantified the effects of climatically driven annual variation in food supply on demographic traits of female pythons (feeding rate, body size, body mass, and reproductive output). Reaction norms linking food supply to feeding rates and residual body mass were broadly linear, whereas norms linking food supply to female body size became curvilinear when a dramatic (flooding-induced) famine reduced the mean body size at sexual maturity. Thus, the reaction norms recorded over 16 years of mal" (albeit highly variable) climatic conditions gave little insight into the population's response to a more extreme nutritional crisis.     

Ecological compensation based on willingness to accept for conservation of drinking water sources

Ecological compensation is a powerful environmental economic tool for environmental protection in areas where drinking water sources are located. We established an ecological compensation accounting system based on respondents’ willingness to accept (WTA). In this system, stakeholder preferences and the factors that influence them can be gauged effectively using logit and tobit models. We applied this accounting system to ecological compensation for the Miyun Reservoir, Beijing, China. The average WTA value for Miyun Reservoir residents was approximately 1186 CNY per family in 2012, which could be set as a suitable compensation standard, since it is slightly higher than the local protection cost. Thus, the annual total ecological compensation could be 58.73 million CNY. Distance from the reservoir, job types, and attitude to environmental protection were variables with significant effects on WTA. In addition, trends for individual preferences were identified via an analysis of key influential factors. The results suggest some useful information for establishing ecological compensation mechanisms for conservation of drinking water sources. Suggestions include popularizing the concept and meaning of ecological compensation among residents, setting different compensation levels based on distance from the reservoir, considering the requirements of farmers, and taking various in-kind and out-of-kind compensation approaches.     

地下水砷污染形成机制研究进展

地下水砷污染是全球饮用水的主要威胁之一,目前全世界有超过一亿人受砷污染地下水问题的困扰.因此,深入研究地下水砷污染的形成机制,对预测地下水中砷的分布及解决地下水砷污染问题具有重要意义.本文在归纳总结前人相关研究的基础上,综述了关于地下水砷污染形成机制的不同解释及最新研究进展,重点阐述了铁氧化物还原溶解释放砷机制,并详细...     

Chronic exposure of arsenic via drinking water and its adverse health impacts on humans

Worldwide chronic arsenic (As) toxicity has become a human health threat. Arsenic exposure to humans mainly occurs from the ingestion of As contaminated water and food. This communication presents a review of current research conducted on the adverse health effects on humans exposed to As-contaminated water. Chronic exposure of As via drinking water causes various types of skin lesions such as melanosis, leucomelanosis, and keratosis. Other manifestations include neurological effects, obstetric problems, high blood pressure, diabetes mellitus, diseases of the respiratory system and of blood vessels including cardiovascular, and cancers typically involving the skin, lung, and bladder. The skin seems to be quite susceptible to the effects of As. Arsenic-induced skin lesions seem to be the most common and initial symptoms of arsenicosis. More systematic studies are needed to determine the link between As exposure and its related cancer and noncancer end points.     

Effects of some trace heavy metals on Poecilia reticulata (Peters)

Three trace heavy metals viz., nickel, copper and zinc were studied for their toxic action against Poecilia retriculata (Peters). Among these, copper was found to be most active followed by zinc and nickel. Accumulations of these metals as well as behavioural studies were carried out after exposing fish to sub-lethal concentration of LC20. It was found that the highest quantity of nickel was accumulated in the fish body followed by zinc and copper. After exposure to sub-lethal concentration of metals some behavioural changes in fish were observed due to stress, such as mucus like secretion over gills, excessive excretion, anoretic condition and increased distance between gills and operculum. In all the cases fin movement was observed. Role and use of such changes as biological indicators or as biological early warning system in water quality assessment has been discussed.     

Geochemical Environment and Health Problems in China

China is a very large developing country covering vast territories and having a complex natural environment. It has an enormous population and numerous endemic diseases. The total population of China is 14 x 10(8) of which 3 x 10(3) live in endemic disease-affected areas and 0.48 x 10(3) suffer from these diseases. The distribution of the endemic diseases has obvious geographical characteristics. Among the most harmful and widely distributed of the endemic diseases are Kaschin-Beck disease, Keshan disease, iodine deficiency, endemic fluorosis and hepatic carcinoma. The geographical environments have a close relationship to endemic diseases and are influenced by climate, geology, landform, soil, food and drinking water. Drinking water is the key issue, since polluted water, or water lacking in or having an excess of certain minerals and elements, as well as water containing certain organic components, has been shown to be harmful to human health. Research has shown that some diseases can be reduced or eliminated by paying attention to the way drinking water is obtained, as well as by improving the nutritional values of the food by eliminating negative components. Fifty years of research has already gone into this subject and there is still much research to be done. This paper puts forth a model of health problems related to geographical environment and the importance of continued research in this field.