Quantitative risk assessment of noroviruses in drinking water based on qualitative data in Japan

Noroviruses are one of the major causes of viral gastroenteritis in Japan. A quantitative risk assessment was conducted to evaluate the health risk caused by this virus in drinking water. A Monte Carlo analysis was used to calculate both the probability of infection and the disease burden using disability-adjusted life years (DALYs). The concentration of noroviruses in tap water was estimated based on qualitative data and a most probable number (MPN) method with an assumed Poisson lognormal distribution. This numerical method was evaluated using two sets of available count data of Cryptosporidium: that collected from a river and that found in tap water in Japan. The dose-response relationships for noroviruses were estimated using assumed ID50 (10 or 100). The annual risk was higher than the US-EPA acceptable level (10(-4) [infection/ person-year]) but around the WHO level (10(-6) [DALYs/ person-year]). As suggested by others, since microbial concentrations are generally lognormally distributed, the arithmetic mean was directly related to the annual risk, suggesting that the arithmetic mean is more useful in representing the degree of microbial contamination than the geometric mean.     

Intake and risk assessment of nitrate and nitrite from New Zealand foods and drinking water

Exposure to excess nitrite is a potential health risk for humans. One hundred meat and processed foods and 100 vegetable samples purchased from New Zealand retail outlets were prepared as for consumption and analysed for nitrite and nitrate concentration using a standard, validated methodology. Nitrate concentrations ranged from less than the limit of detection (LOD = 5 mg kg^-1) in cheddar cheese and cream cheese-based dips to 3420 mg kg^-1 in lettuce. Nitrite was detected in half the processed foods and meats analysed (levels up to 119 mg kg^-1), but detected in only one vegetable sample above the LOD (broccoli at 27 mg kg^-1 nitrite). Concentration data were combined with 24 h dietary recall information to generate 4398 individual adult daily exposure scenarios for exogenous nitrite and nitrate including a contribution from water assessed from 1021 drinking water samples. The mean adult daily intake of exogenous nitrate and nitrite from food and water combined was 16 and 13% of the Acceptable Daily Intake (ADI), respectively, and therefore should not pose a health risk for the average consumer. A maximally exposed New Zealand adult is estimated to have an intake of up to seven times the ADI for nitrate. When the endogenous conversion of nitrate to nitrite is taken into account, approximately 10% of people with an average rate of conversion and half of all people with a high rate of conversion are estimated to exceed the ADI. Either the ADI is inappropriate and needs to be re-evaluated, or those individuals who have a high rate of conversion of nitrate to nitrite are at risk to adverse effects of nitrite exposure.     

Rapid detection and toxicity assessment of citreoviridin using luminescent Vibrio qinghaiensis sp.‐Q67 in drinking water

Citreoviridin (CIT), one of the mycotoxins produced by Penicillium citreoviridin (PCV), is a common contaminant in a wide range of agricultural products and is detrimental to human and animal health. There is potential threat that terrorists can extract CIT from mouldy cereals, such as rice which forms the major source of starch intake in Asia–Pacific diets and corns which are readily available. The objective of this study was to develop a rapid method for detection of citreoviridin and evaluate its performance on luminescent bacterium Vibrio qinghaiensis sp.‐Q67 (Q67). A good correlation (R² > 0.98) between concentrations of CIT and the relative luminosity unit of Q67 was obtained with a linear range from 0.0005 to 0.01 mg L^?1. The precision expressed as relative standard deviation (RSD) was 3.2% for eleven replicate determinations of 0.005 mg L^?1 CIT, and the recoveries of spiked samples were 88%–93%. The luminescence inhibition ratio of CIT increased from 0.0005 to 0.5 mg L^?1, and the luminescence inhibition ratio remained stable at approximately 85% in the range of 0.5–10 mg L^?1. The system detected low traces (≤0.0005 mg L^?1) of CIT, and it has potential to be used as rapid detection method for mycotoxins. The effect of pure CIT on Q67 was time dependent and, it was the strongest (EC₅₀ = 0.0066) at 20 min which indicated the high effect of CIT on Q67. Results obtained in this study suggest that Q67 is a promising method for rapid evaluation of the toxicity of CIT. Therefore, the luminescent bacteria assay can potentially be used as a system in monitoring sudden pollution in drinking water.     

Linking quantitative microbial risk assessment and epidemiological data: informing safe drinking water trials in developing countries

Intervention trials are used extensively to assess household water treatment (HWT) device efficacy against diarrheal disease in developing countries. Using these data for policy, however, requires addressing issues of generalizability (relevance of one trial in other contexts) and systematic bias associated with design and conduct of a study. To illustrate how quantitative microbial risk assessment (QMRA) can address water safety and health issues, we analyzed a published randomized controlled trial (RCT) of the LifeStraw Family Filter in the Congo. The model accounted for bias due to (1) incomplete compliance with filtration, (2) unexpected antimicrobial activity by the placebo device, and (3) incomplete recall of diarrheal disease. Effectiveness was measured using the longitudinal prevalence ratio (LPR) of reported diarrhea. The Congo RCT observed an LPR of 0.84 (95% CI: 0.61, 1.14). Our model predicted LPRs, assuming a perfect placebo, ranging from 0.50 (2.5-97.5 percentile: 0.33, 0.77) to 0.86 (2.5-97.5 percentile: 0.68, 1.09) for high (but not perfect) and low (but not zero) compliance, respectively. The calibration step provided estimates of the concentrations of three pathogen types (modeled as diarrheagenic E. coli, Giardia, and rotavirus) in drinking water, consistent with the longitudinal prevalence of reported diarrhea measured in the trial, and constrained by epidemiological data from the trial. Use of a QMRA model demonstrated the importance of compliance in HWT efficacy, the need for pathogen data from source waters, the effect of quantifying biases associated with epidemiological data, and the usefulness of generalizing the effectiveness of HWT trials to other contexts.     

饮用天然矿泉水中锶的测定

建立了用电感耦合等离子体光度发射光谱（ICP-OES）法测定饮用天然矿泉水中锶的新方法.优选了试剂介质和仪器条件.方法简单、快速、灵敏度高.锶的检出限为0.0002mg/L,相对标准偏差小于2%（RSD,n=10）,用于饮用天然矿泉水中锶的测定取得了满意的结果.     

Misinterpretation of drinking water quality monitoring data with implications for risk management

A survey of two groups of environmental professionals was conducted to explore the degree of understanding in the interpretation of monitoring results for informing decision-making and responding to data appropriately to manage environmental health risks. Specifically, the understanding of the predictive value of a monitoring result and the appreciation that false positive results will inevitably predominate when monitoring for rare or infrequent hazards was explored. Results indicate evidence of misinterpretation and overconfidence in the meaning of monitoring results, and the ability of laboratory methods to detect reliably an infrequent hazard in environmental samples. A hypothetical monitoring scenario was presented with characteristics sufficient to estimate what level of confidence was warranted in a positive result. The majority of respondents in both groups (most of whom had more than 10 years experience in their field) reported between very likely to almost certain confidence (80-100% likelihood) in a hypothetical monitoring result which was, in fact, less than 5% likely to be correct. Additionally, there was little influence of the beliefs expressed about the validity of the monitoring result on the actions proposed to be taken in response to finding that monitoring result. The independence of respondents' follow-up action to what they believe of a monitoring result implies a level of detachment between the understanding of the monitoring data and the resulting risk management response.     

瓶(桶)装饮用纯净水微生物检测方法

通过瓶（桶）装饮用纯净水微生物检测过程,指出对样品的取样、培养基的制备及其整个操作过程应注意事项,提高了微生物检测的准确度。     

快速检测饮用水中铬(VI)的光电型传感器的建立

利用二苯碳酰二肼与铬络合显色的原理,将二苯碳酰二肼固定化制成试纸条,插入自制的便携式单色光反射计中,组装出检测饮用水中铬的光电型传感器。实验结果表明:当铬的浓度范围处于0.0019～0.58mmol/L时,光反射率与铬浓度呈现良好的线性关系。经过检测条件优化后,该技术的检出限为0.00019mmol/L,检测时间为3min。此种方法检测饮用水中的铬灵敏度高、检测时间短、操作简便,能够实现铬的现场检测。     

Bacteriological quality of drinking water from dispensers (coolers) and possible control measures

Three water dispensers (coolers) were bacteriologically monitored over a period of 3 months to evaluate their hygienic status. For this purpose, 174 samples of chilled and unchilled water were analyzed for levels of mesophilic aerobic bacteria and the presence of Escherichia coli and enterococci in 100-ml samples, and the presence of Pseudomonas aeruginosa in 10- and 100-ml samples. Additionally, 12 samples from 20-liter plastic bottles of spring water used to supply the coolers and 36 samples of 12 different brands of noncarbonated bottled mineral water were similarly analyzed. Water from the coolers yielded aerobic plate counts of 3 to 5 log CFU/ml with a geometric mean of 3.86 log CFU/ml, whereas water from the 20-liter bottles had a mean aerobic plate count of 3.3 log CFU/ml. Aerobic plate counts for noncarbonated mineral waters were generally lower (13 samples, < 10 CFU/ml; 6 samples, 10 to 10(2) CFU/ml; 13 samples, 10(2) to 10(3) CFU/ml; 3 samples, 10(3) to 10(4) CFU/ ml; 1 sample, 2 x 10(4) CFU/ml). Although occasional professional cleaning of the coolers did not affect the aerobic plate count, P. aeruginosa was successfully eliminated 2 weeks after cleaning, with only one cooler becoming recolonized. Neither E. coli nor enterococci was found in any of the water samples tested. However, P. aeruginosa was identified in three (25%) of twelve 100-ml samples from 20-liter bottles of spring water; a similar frequency of 24.1% was seen for water samples from coolers. Overall, 35 (21.6%) of 162 water samples (10 ml) from coolers also yielded P. aeruginosa, suggesting potential growth of P. aeruginosa in the dispensers. Pulsed-field gel electrophoresis typing and antibiotic susceptibility testing found 19 P. aeruginosa isolates from the coolers and bottles to be identical, indicating that a single strain originated from the bottled water rather than the surroundings of the coolers. Because P. aeruginosa can cause serious nosocomial infections, its spread should be strictly controlled in institutions caring for vulnerable people such as hospitals and nursing homes. Consequently, in keeping with legal requirement for bottled spring and mineral water in Switzerland, it is also advisable that P. aeruginosa be absent in 100-ml samples of cooler water.     

Bioanalytical assessment of the formation of disinfection byproducts in a drinking water treatment plant

Disinfection of drinking water is the most successful measure to reduce water-borne diseases and protect health. However, disinfection byproducts (DBPs) formed from the reaction of disinfectants such as chlorine and monochloramine with organic matter may cause bladder cancer and other adverse health effects. In this study the formation of DBPs through a full-scale water treatment plant serving a metropolitan area in Australia was assessed using in vitro bioanalytical tools, as well as through quantification of halogen-specific adsorbable organic halogens (AOXs), characterization of organic matter, and analytical quantification of selected regulated and emerging DBPs. The water treatment train consisted of coagulation, sand filtration, chlorination, addition of lime and fluoride, storage, and chloramination. Nonspecific toxicity peaked midway through the treatment train after the chlorination and storage steps. The dissolved organic matter concentration decreased after the coagulation step and then essentially remained constant during the treatment train. Concentrations of AOXs increased upon initial chlorination and continued to increase through the plant, probably due to increased chlorine contact time. Most of the quantified DBPs followed a trend similar to that of AOXs, with maximum concentrations observed in the final treated water after chloramination. The mostly chlorinated and brominated DBPs formed during treatment also caused reactive toxicity to increase after chlorination. Both genotoxicity with and without metabolic activation and the induction of the oxidative stress response pathway showed the same pattern as the nonspecific toxicity, with a maximum activity midway through the treatment train. Although measured effects cannot be directly translated to adverse health outcomes, this study demonstrates the applicability of bioanalytical tools to investigate DBP formation in a drinking water treatment plant, despite bioassays and sample preparation not yet being optimized for volatile DBPs. As such, the bioassays are useful as monitoring tools as they provide sensitive responses even at low DBP levels.     

Determination of perfluoroalkylated substances (PFASs) in drinking water from the Netherlands and Greece

In the present study 11 perfluoroalkylated substances (PFASs) were analysed in drinking tap water samples from the Netherlands (n = 37) and from Greece (n = 43) by applying LC-MS/MS and isotope dilution. PFASs concentrations above the limit of quantification, LOQ (0.6 ng/l) were detected in 20.9% of the samples from Greece. Total PFAS concentrations ranged between <LOQ and 5.9 ng/l, with the highest concentrations noted for the three Aegean islands Mykonos, Kalymnos and Syros and for the town Tripoli in the Peloponnese. In the Dutch situation, total PFASs concentrations above the LOQ were detected in 48.6% of the samples, varying from <LOQ to 54 ng/l. The highest concentrations were detected around Amsterdam (including Schiphol airport) and more generally, PFASs were detected in the drinking water from the western part of the Netherlands. This seems attributable to the source, which is purified surface water in this area. Short-chain PFASs and especially perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorobutane sulfonate (PFBS), and perfluorohexane sulfonate (PFHxS) were detected most frequently, whereas long-chain PFASs (C > 8) were only rarely detected. In the drinking water samples from the eastern part of the Netherlands, where drinking water is sourced from groundwater reservoirs, no PFASs were detected. This demonstrates that exposure to PFASs through drinking water in the Netherlands is dependent on the source. Additionally, five samples of bottled water from each country were analysed in the current study, with all of them originating from ground wells. In these samples, all PFASs were below the LOQ.     

Enteric virus infection risk from intrusion of sewage into a drinking water distribution network

Contaminants from the soil surrounding drinking water distribution systems are thought to not enter the drinking water when sufficient internal pressure is maintained. Pressure transients may cause short intervals of negative pressure, and the soil near drinking water pipes often contains fecal material due to the proximity of sewage lines, so that a pressure event may cause intrusion of pathogens. This paper presents a risk model for predicting intrusion and dilution of viruses and their transport to consumers. Random entry and dilution of virus was simulated by embedding the hydraulic model into a Monte Carlo simulation. Special attention was given to adjusting for the coincidence of virus presence and use of tap water, as independently occurring short-term events within the longer interval that the virus is predicted to travel in any branch of the distribution system. The probability that a consumer drinks water contaminated with virus is small, but when this happens the virus concentration tends to be high and the risk of infection may be considerable. The spatial distribution of infection risk is highly heterogeneous. The presence of a chlorine residual reduces the infection risk.     

Residues of doxycycline and oxytetracycline in eggs after medication via drinking water to laying hens

Doxycycline (DOTC) and oxytetracycline (OTC) were dissolved in drinking water (0.5 g/l) and supplied to laying hens for 7 consecutive days. Eggs laid were collected daily during and after medication, and the antibiotic concentrations in the yolk and albumin were determined by the cup-plate method with Bacillus cereus var. mycoides ATCC 11778. The concentrations of both antibiotics were increased in yolk day by day with the advance in medication, reached peaks 2 days after withdrawal and then declined gradually. Mean peak concentrations in the yolk were 6.70 micrograms/g for DOTC and 1.42 micrograms/g for OTC. Peak concentrations in the albumin occurred in the middle stage of medication, where the mean values were 12.24 micrograms/g for DOTC and 1.03 micrograms/g for OTC. DOTC was detected in albumin until 24 days after withdrawal and for 2 days more in yolk than in albumin. OTC was detected in yolk until 9 days after withdrawal. The depletion period of OTC was shorter for the albumin, where the residue disappeared in all eggs 6 days after withdrawal. In spite of similarities between DOTC and OTC in structure, DOTC was deposited in higher concentrations and lasted for a longer period in eggs. This characteristic was considered due to its greater lipophilicity, closely correlated with oral absorption and tissue penetration.     

电感耦合等离子发射光谱法测定矿泉水和饮用水中微量钒

研究使用电感耦合等离子发射光谱法（ICP-AES）快速测定矿泉水和饮用水中微量钒,确定了最佳仪器工作条件。方法检出限为0.002mg/L,相对标准偏差（RSD）为0.42%～0.77%,回收率在98.5%～101.7%之间。该方法简便、快速、准确,结果令人满意。     

饮用天然矿泉水中偏硅酸(H2SiO3)的测定

建立了全谱直读等离子体光学发射光谱（ICP—OES）法测定饮用天然矿泉水中偏硅酸（H2SiO3）的新方法，优选了试液介质和仪器条件。方法简单、快速、灵敏度高．偏硅酸（H2SiO3）的栓出限为0．09mg／L。相时标准偏差小于1％，用于饮用天然旷泉水中偏硅酸的测定，取得了满意的结果．     

Virulence and risk from drinking water of heterotrophic plate count bacteria in human population groups

Bacteria are natural inhabitants of all aqueous environments. The heterotrophic plate count is a means of assessing the concentration of these bacteria in foods, water, and water filtration systems. Methods vary, but are designed to enumerate bacteria that have evolved an environmental lifestyle. Most commonly, low nutrient, low ionic strength culture media are employed. The group of environmental bacteria enumerated depends on the media formulation and incubation conditions but are commonly known as heterotrophic plate count (HPC) bacteria; in Europe, this group is also referred to as autochthonous flora. While HPC inhabit an environmental niche, there has been concern that at some concentration they may be a human health risk. A review of the literature, including animal and human feeding studies, analysis of virulence factors, and outbreaks demonstrates that HPC bacteria as enumerated on HPC culture media have not been established as a human health threat at any concentration in drinking water or foods.     

Bead-based competitive fluorescence immunoassay for sensitive and rapid diagnosis of cyanotoxin risk in drinking water

Due to the increased occurrence of cyanobacterial blooms and their toxins in drinking water sources, effective management based on a sensitive and rapid analytical method is in high demand for security of safe water sources and environmental human health. Here, a competitive fluorescence immunoassay of microcystin-LR (MCYST-LR) is developed in an attempt to improve the sensitivity, analysis time, and ease-of-manipulation of analysis. To serve this aim, a bead-based suspension assay was introduced based on two major sensing elements: an antibody-conjugated quantum dot (QD) detection probe and an antigen-immobilized magnetic bead (MB) competitor. The assay was composed of three steps: the competitive immunological reaction of QD detection probes against analytes and MB competitors, magnetic separation and washing, and the optical signal generation of QDs. The fluorescence intensity was found to be inversely proportional to the MCYST-LR concentration. Under optimized conditions, the proposed assay performed well for the identification and quantitative analysis of MCYST-LR (within 30 min in the range of 0.42-25 μg/L, with a limit of detection of 0.03 μg/L). It is thus expected that this enhanced assay can contribute both to the sensitive and rapid diagnosis of cyanotoxin risk in drinking water and effective management procedures.     

Health risk assessment of Chinese consumers to nickel via dietary intake of foodstuffs

A quantitative risk assessment was carried out to characterise the health risk from nickel (Ni) via dietary exposure for Chinese consumers. Ni contamination in foods was investigated by conducting a survey and a literature review. The daily diet of the public was categorised into nine food groups and the consumption data for each group were obtained from a nationwide survey. Deterministic and probabilistic methods were applied to calculate the target hazard quotients (THQs) by comparing the estimated dietary Ni intake with respect to the tolerable daily intake (TDI). The average estimated daily Ni intake (μg kg^–1 bw day^–1) for men, women, 2–3-year-old children and 4–17-year-old children were 7.2, 7.3, 17.1 and 10.0, respectively. The consumption of cereals, beans, vegetables and marine products contributed significantly to the total daily intake of Ni. The mean THQ values (95% confidence interval) and the probability of dietary Ni exposure higher than the TDI were 0.60 (0.58–0.62) and 8.2% for men, 0.61 (0.59–0.63) and 8.4% for women, 1.35 (1.32–1.39) and 72.0% for 2–3-year-old children, and 0.87 (0.82–0.91) and 28.5% for 4–17-year-old children, respectively. This study showed a potential health risk from Ni via dietary exposure for Chinese consumers, especially among children.     

The risk of transmission of variant Creutzfeldt-Jakob disease via contact lenses and ophthalmic devices.

This review collated the available information regarding the risk of transmission of variant Creutzfeldt-Jakob disease (vCJD) via contact lenses and other ophthalmic devices. The topics examined include: the emerging background science of the unconventional infective agent, the prion, particularly those factors affecting transmission; the estimates of the number of undiagnosed infective individuals; and evidence of infectivity in the external eye. Despite many uncertainties in the literature, we conclude that cross-infection is theoretically possible. An assessment of the extensive search for a complete inactivation procedure resulted in the recommendation of the use of sodium hypochlorite (NaOCl), which does not appear to distort rigid lenses. Further tests are required for other devices.