Efficiency of water rinsing for the decontamination of used pesticide containers

The efficiency of water rinsings for the decontamination of emptied pesticide containers was investigated in the period 1979–1981; nineteen formulations representing seven insecticides and two fungicides were studied. Following normal emptying procedures, the amount of retained pesticides ranged from a low of 0.06% to a high of 7.48%. By successively rinsing with volumes of water equal to one-tenth of the volume of the containers, as many as five rinses were required to remove 99% of the retained formulation. When containers were held in an inverted position and allowed to drain one minute prior to rinsing, three successive rinsings were sufficient for most formulations to remove 99% of the retained pesticide. Decontamination by rinsing was achieved most readily with water-soluble concentrates and wettable powders while flowable suspensions appeared to be the most difficult to remove.     

Control of Aedes aegypti larvae in household water containers by Chinese cat fish

In 1980-81 an outbreak of dengue fever occurred in Guangdong province and in Guangxi-Zhuang autonomous region in the central-southern part of China. Subsequently, a nationwide survey indicated that the vector of the disease, Aedes aegypti, was confined to the coastal strip of Guangdong and Guangxi-Zhuang. Since the first case in the outbreak occurred in Guangxi-Zhuang, a community-based programme to control A. aegypti was set up in eight fishing villages of this region where the mosquito was breeding in household water containers. The principal method of control was use of the indigenous edible fish Clarias fuscus (Chinese cat fish), which is highly larvivorous and tolerant of harsh environmental conditions. Each container was stocked with a young fish, which could survive there for periods of up to a year. A team of primary medical personnel (barefoot doctors) made sure that the programme was correctly implemented. The programme was monitored from 1981 to 1985 in three of the villages, and the results indicated that the Breteau index remained at a low level throughout this period.     

The effectiveness of large household water storage tanks for protecting the quality of drinking water

Many communities along the US-México border remain without infrastructure for water and sewage. Residents in these communities often collect and store their water in open 55-gallon drums. This study evaluated changes in drinking water quality resulting from an intervention that provided large closed water storage tanks (2,500-gallons) to individual homes lacking a piped water supply. After the intervention, many of the households did not change the source of their drinking water to the large storage tanks. Therefore, water quality results were first compared based on the source of the household's drinking water: store or vending machine, large tank, or collected from a public supply and transported by the household. Of the households that used the large storage tank as their drinking water supply, drinking water quality was generally of poorer quality. Fifty-four percent of samples collected prior to intervention had detectable levels of total coliforms, while 82% of samples were positive nine months after the intervention (p < 0.05). Exploratory analyses were also carried out to measure water quality at different points between collection by water delivery trucks and delivery to the household's large storage tank. Thirty percent of the samples taken immediately after water was delivered to the home had high total coliforms (>10 CFU/100 ml). Mean free chlorine levels dropped from 0.43 mg/l, where the trucks filled their tanks, to 0.20 mg/l inside the household's tank immediately after delivery. Results of this study have implications for interventions that focus on safe water treatment and storage in the home, and for guidelines regarding the level of free chlorine required in water delivered by water delivery trucks.     

The effectiveness of large household water storage tanks for protecting the quality of drinking water

Many communities along the US-Mexico border remain without infrastructure for water and sewage. Residents in these communities often collect and store their water in open 55-gallon drums. This study evaluated changes in drinking water quality resulting from an intervention that provided large closed water storage tanks (2,500-gallons) to individual homes lacking a piped water supply. After the intervention, many of the households did not change the source of their drinking water to the large storage tanks. Therefore, water quality results were first compared based on the source of the household's drinking water: store or vending machine, large tank, or collected from a public supply and transported by the household. Of the households that used the large storage tank as their drinking water supply, drinking water quality was generally of poorer quality. Fifty-four percent of samples collected prior to intervention had detectable levels of total coliforms, while 82% of samples were positive nine months after the intervention (p < 0.05). Exploratory analyses were also carried out to measure water quality at different points between collection by water delivery trucks and delivery to the household's large storage tank. Thirty percent of the samples taken immediately after water was delivered to the home had high total coliforms (> 10 CFU/100 ml). Mean free chlorine levels dropped from 0.43 mg/l, where the trucks filled their tanks, to 0.20 mg/l inside the household's tank immediately after delivery. Results of this study have implications for interventions that focus on safe water treatment and storage in the home, and for guidelines regarding the level of free chlorine required in water delivered by water delivery trucks.     

Effect of production variables on microbiological removal in locally-produced ceramic filters for household water treatment

Diarrhoeal diseases cause an estimated 1.87 million child deaths per year. Point-of-use filtration using locally made ceramic filters improves microbiological quality of stored drinking water and prevents diarrhoeal disease. Scaling-up ceramic filtration is inhibited by lack of universal quality control standards. We investigated filter production variables to determine their affect on microbiological removal during 5–6 weeks of simulated normal use. Decreases in the clay:sawdust ratio and changes in the burnable decreased effectiveness of the filter. Method of silver application and shape of filter did not impact filter effectiveness. A maximum flow rate of 1.7 l^?hr was established as a potential quality control measure for one particular filter to ensure 99% (2- log₁₀) removal of total coliforms. Further research is indicated to determine additional production variables associated with filter effectiveness and develop standardized filter production procedures prior to scaling-up.     

The microbiological quality of seven large commercial private water supplies in the United Kingdom

Some 1% of the UK population derives their potable water from 140,000 private water supplies (PWSs) regulated by Local Authorities. The overwhelming majority of these are very small domestic supplies serving a single property or a small number of properties. Treatment for such supplies is rudimentary or non-existent and their microbiological quality has been shown to be poor in every published study to date. Private water supplies serving commercial enterprises such as hotels, restaurants, food production premises and factories are more frequently treated and subject to closer regulation in the United Kingdom. As a result, it has been assumed that these larger commercial supplies are less likely to experience elevated faecal indicator and pathogen concentrations at the consumer tap which have been observed at small domestic supplies.     

The microbiological quality of seven large commercial private water supplies in the United Kingdom

Some 1% of the UK population derives their potable water from 140,000 private water supplies (PWSs) regulated by Local Authorities. The overwhelming majority of these are very small domestic supplies serving a single property or a small number of properties. Treatment for such supplies is rudimentary or non-existent and their microbiological quality has been shown to be poor in every published study to date. Private water supplies serving commercial enterprises such as hotels, restaurants, food production premises and factories are more frequently treated and subject to closer regulation in the United Kingdom. As a result, it has been assumed that these larger commercial supplies are less likely to experience elevated faecal indicator and pathogen concentrations at the consumer tap which have been observed at small domestic supplies.This paper reports on intensive monitoring at seven commercial private water supplies (six of which were treated) spread throughout the UK serving hotels, holiday parks and food production enterprises. Daily sampling of 'potable' water, both at the consumer tap and using large volume filtration for Giardia and Cryptosporidium spp. was conducted over two six week periods in the spring and autumn of 2000. This allowed the effects of short term episodic peaks in faecal indicator and pathogen concentration to be quantified. All the supplies experienced intermittent pathogen presence and only one, a chlorinated deep borehole supply, fully complied with UK water quality regulations during both periods of sampling.Poor microbiological water quality typically followed periods of heavy rainfall. This suggests that the design and installation of such systems should be undertaken only after the likely range of raw water quality has been characterised, which requires a thorough understanding of the effects of flow and seasonality on raw water quality. There is no reason to suspect that the monitored sites are uncharacteristic of other commercial supplies and the results reinforce public health concerns related to domestic supplies. Furthermore, the pattern of contamination is highly episodic, commonly lasting only a few days. Thus, the relatively infrequent regulatory monitoring of such supplies would be unlikely to identify the poor water quality episodes and does not provide the data necessary for public health protection. Although some statistical relationship was found between faecal indicator organisms and the presence of pathogens, the use of FIOs in assessments of regulatory compliance may not always provide a reliable measure of public health risk, i.e. indicator absence does not preclude pathogen presence. The results of this study suggest that a risk assessment system similar to the WHO 'Water Safety Planning' approach might offer a more appropriate regulatory paradigm for private water supplies.     

A survey of the microbiological quality of private water supplies in England

Results from statutory testing of private water supplies in nine Public Health Laboratories in England were compiled, and the effects of supply class, source, treatment and location on water quality were examined. A total of 6551 samples from 2911 supplies was examined, over a 2-year period, of which 1342 (21%) samples, and 949 (33%) supplies on at least one occasion, failed current regulations for Escherichia coli. Total coliforms, including E. coli, were detected in 1751 (27%) samples from 1215 (42%) supplies. The percentage of samples positive for E. coli was highest in summer and autumn, and lowest in winter. Samples taken from larger supplies and from boreholes were less frequently contaminated than those from other sources. Chlorination, filtration or UV light treatment improved the bacteriological quality of supplies, but still resulted in a low level of compliance with the regulations. The public health implications of the study are discussed.     

Community and household determinants of water quality in coastal Ghana

Associations between water sources, socio-demographic characteristics and household drinking water quality are described in a representative sample of six coastal districts of Ghana's Central Region. Thirty-six enumeration areas (EAs) were randomly chosen from a representative survey of 90 EAs in rural, semi-urban and urban residence strata. In each EA, 24 households were randomly chosen for water quality sampling and socio-demographic interview. Escherichia coli per 100 ml H₂O was quantified using the IDEXX Colilert^® system and multi-stage regression models estimated cross-sectional associations between water sources, sanitation and socio-demographic factors. Almost three quarters, 74%, of the households have >2 E. coli /100 ml H₂O. Tap water has significantly lower E. coli levels compared with surface or rainwater and well water had the highest levels. Households with a water closet toilet have significantly lower E. coli compared with those using pit latrines or no toilets. Household size is positively associated, and a possessions index is negatively associated, with E. coli. Variations in community and household socio-demographic and behavioural factors are key determinants of drinking water quality. These factors should be included in planning health education associated with investments in water systems.     

An assessment of microbiological water quality of six water source categories in north-east Uganda

Target 7C of the Millennium Development Goals is to “halve, by 2015, the proportion of people without sustainable access to safe drinking water and basic sanitation”. However, the corresponding indicator measures the “proportion of population using an improved drinking water source”. This raises the question of whether “safe” and “improved” can be used interchangeably. This paper tests this hypothesis by comparing microbiological water quality in 346 different water sources across the District of Amuria in Uganda to each other and to defined standards, including the WHO drinking water standard of zero TTC per 100 ml, and the Ugandan national standard of 50 TTC per 100 ml. The water sources were grouped into six different categories: boreholes, protected springs, covered hand dug wells, open hand dug wells, open water and roofwater harvesting. The paper concludes that the ranking from the highest to the lowest microbiological quality water was: boreholes, protected springs and roofwater harvesting, open and covered hand dug wells, open water. It also concludes that sanitary surveys cannot be used to predict water quality precisely; however they are an essential component of the monitoring of safe water supplies.     

Risks associated with the microbiological quality of bodies of fresh and marine water used for recreational purposes: summary estimates based on published epidemiological studies

The current European standards for microbiological quality of bathing water (i.e., all running or still fresh waters or parts thereof and/or sea water [with the exception of water intended for therapeutic purposes and water used in swimming pools]) were issued in 1976 and are currently undergoing revision. In this article, the authors propose parameters for select microorganism indicators to assist in the establishment of public-health-based objectives for fresh and marine water quality. A type-II meta-analysis of the results of 18 published epidemiological studies was implemented in an attempt to characterize the relationship(s) between concentrations of bacterial indicators and rates of acute gastrointestinal diseases among bathers who had used fresh or marine water for recreational purposes. The authors fit multiple linear-regression models, which allowed for random effects across studies, to derive dose-response curves. Several confounders and effect modifiers were controlled for in the analyses. Risks were then estimated for a hypothetical individual who would bathe 20 times/yr in water that contained a given concentration of microorganisms. For fresh-water-associated highly credible gastrointestinal illnesses, a level of 10 fecal coliforms/100 ml water yielded an attributable risk of 0.2 cases/1,000 person-years; a risk of 2 cases/1,000 person-years was found for fecal streptococci. The corresponding yearly attributable risks were 1 and 13 cases/1,000 person-years, respectively, for 100 bacteria/100 ml fresh water. Risks associated with fecal coliforms were found to be lower in marine water than in fresh water. Irrespective of the type of water examined, total coliforms were related only weakly with acute digestive morbidity. Developers of future bathing-water standards should state the level of risk deemed acceptable for public health. The authors of this study maintain that levels of fecal coliforms and fecal streptococci should be used as criteria for infectious risk management associated with bodies of marine and fresh water used for recreational purposes.     

The effect of microbiological containment systems on dexterity

Microbiology laboratories use containment equipment such as safety cabinets and isolators or respiratory protective equipment to protect workers against aerosol infection hazards. There is a perception among microbiologists that the use of containment equipment reduces dexterity to a point where the risks associated with using sharps are increased. Thus, in a situation where it is essential to use sharps, the use of respiratory protection is frequently the favored method of operator protection. Using three methods of manual dexterity testing, the effect of latex gloves, a positive pressure respirator, and three forms of containment equipment, (a Class II safety cabinet, a half suit, and a flexible film isolator) were tested against performance in these tests using bare hands in 10 subjects. The study was extended to additionally assess Class III cabinets using 20 subjects. With the exception of latex gloves, the personal protective equipment and containment equipment all had a statistically significant detrimental effect on manual dexterity compared with working solely with bare hands. The use of containment systems, especially barrier containment systems such as Class III cabinets and isolators, significantly reduces dexterity and may increase the chance of accidents. The use of positive pressure respirators with double gloves also affects dexterity but to a lesser extent. The use of sharps should be minimized within containment equipment. Risk assessment may be required to address the comparative risk of aerosol and needlestick infection with different agents to choose the most appropriate containment systems.     

2010年家用净水器零部件卫生状况调查

目的了解家用净水器零部件的卫生质量,为家用净水器的卫生监督管理提供依据。方法按照《卫生部涉及饮用水卫生安全产品检验规定》(2001),对2010年送检的家用净水器零部件进行卫生安全性检测。结果家用净水器水处理材料中活性炭滤芯(16.39%,20/122)和离子交换树脂(25.00%,10/40)的不合格率相对较高;输配水设备中端帽(20.83%,5/24)和密封圈垫(33.30%,4/12)不合格率相对较高。超标的项目主要包括TDS,氟化物,三氯甲烷,耗氧量、挥发酚、铅、砷、汞、镍、锌。结论活性炭滤芯、离子交换树脂、端帽和密封圈垫的卫生质量是制约家用净水器卫生质量的主要因素,应对其加强卫生监督管理。     

Water quality deterioration: a study of household drinking water quality in rural Honduras

There is growing awareness that drinking-water can become contaminated following its collection from communal sources such as wells and tap-stands, as well as during its storage in the home. This study evaluated the post-supply drinking-water quality in three rural Honduran communities using either a protected hand-dug well or borehole supply. Water management practices were documented as a basis for further research to improve household drinking-water quality. Membrane filtration was used to compare thermotolerant coliform levels in samples taken from community wells and household drinking-water storage containers. Over a 2-year period, water quality was examined in 43 households and detailed observation made of typical collection, storage and usage practice. Substantial water quality deterioration occurred between the points of supply and consumption. Deterioration occurred regularly and frequently, and was experienced by the majority of study households. Only source water quality appeared to be a significant factor in determining household water quality. None of the storage factors examined, i.e. covering the container, type of container, the material from which the container was made, and hours stored, made any significant difference to the stored water quality. Observation of household water management shows that there are multiple points during the collection to use sequence where pollution could occur. The commonality of water management practice would be an asset in introducing appropriate intervention measures.     

The microbiological quality of soft ice-cream from fixed premises and mobile vendors

A microbiological study of soft ice-creams and the mixes used to prepare them examined the effect of the microbiological quality of the mixes on the final product. Among 1246 soft ice-creams from fixed premises and mobile vendors one (< 1%) was of unacceptable quality and a further 327 (26%) were of unsatisfactory quality. The unacceptable sample contained Staphylococcus aureus in excess of 104 cfu g-1. The samples with unsatisfactory results had high aerobic plate (APC) and Enterobacteriaceae counts. Of the 597 mix samples examined, liquid mixes were of poorer microbiological quality than powders due to the presence of high APC (> 105 cfu ml-1) and Enterobacteriaceae (> 104 cfu ml-1) counts. The microbiological quality of soft ice-cream was dependent on the type of mix and dispensing machine used and the frequency of cleaning. Samples from fixed premises were of higher quality than those from mobile vendors. Although most soft ice-creams (74%) were of an acceptable microbiological quality, evidence from this study indicates that the microbiological quality of soft ice-cream sold from certain outlets in the UK remains a cause of concern.     

The health-related microbiological quality of bottled drinking water sold in Dar es Salaam, Tanzania

The consumption of bottled and plastic-bagged drinking water in Tanzania has increased largely because of the deteriorating quality of tap water. It is uncertain whether these water products are safe for drinking. In this study, the microbiological quality of bottled and plastic-bagged drinking water sold in Dar es Salaam, Tanzania, was investigated. One hundred and thirty samples representing 13 brands of bottled water collected from shops, supermarkets and street vendors were analysed for total coliform and faecal coliform organisms as well as heterotrophic bacteria. These were compared with 61 samples of tap water. Heterotrophic bacteria were detected in 92% of the bottled water samples analysed. Total and faecal coliform bacteria were present in 4.6% and 3.6%, respectively, of samples analysed with a tendency for higher contamination rates in plastic-bagged drinking water. Microbiological quality of tap water was found to be worse compared with bottled water, with 49.2% and 26.2% of sampling points showing the presence of total coliform and faecal coliform organisms, respectively. The results suggest caution and vigilance to avert outbreaks of waterborne diseases from these types of drinking water.