How current risk assessment and risk management methods for drinking water in The Netherlands cover the WHO water safety plan approach.

In the Netherlands, safe and sufficient drinking water is provided to the general population by ten drinking water companies. To guarantee safe drinking water the World Health Organization (WHO) developed a Water Safety Plan (WSP), a Risk Assessment and a Risk Management (RA/RM) framework. The objective of the study was to identify legally required RA approaches, to document application of RA/RM activities at Dutch drinking water companies and to determine to what extent these RA/RM activities as a whole cover all the elements of the WHO WSP approach. This study could be of interest to both managers of large water utilities and decision makers. The assessment was performed by means of a policy review and interviews with two to four staff members involved in RA/RM from all ten Dutch drinking water companies combined with a joint workshop. The drinking water companies are well aware of the potential hazards and risks that can influence the drinking water quality. To guarantee the supply of safe and sufficient drinking water, the Dutch drinking water sector uses six different legally required RA/RM approaches. This study shows that by using the six legally required RA/RM approaches, all WSP steps are covered. WSP entails a generic risk assessment for identifying all hazards and hazardous events from source to tap, whereas the six legally required RA/RM each focus on specific risks at an advanced level. Each risk assessment provides information on specific hazards and hazardous events covering a part of the water supply chain. These legal requirements are complemented with additional RA/RM activities at sector and water company level such as codes of practices and standard operating procedures. The outcomes of all RA/RM approaches combined provide information from source to tap. When using multiple RA/RM approaches, it is crucial to share and combine information derived from the different activities.

Demographic projections of future pharmaceutical consumption in the Netherlands.

Over the next few decades, many Western European countries will undergo a large demographic transformation introduced by the retirement of the "baby boomers" and the possibility of striking increases in longevity. The aim of this study was to estimate the effect of a growing and ageing Dutch population on the future consumption of pharmaceuticals, so as to be able to anticipate the potential future emissions of these pharmaceuticals and their residues to surface waters. A total of 354 prescribed pharmaceuticals from 40 therapeutic groups was selected for study. These constitute 1.251 metric tonnes (98%) of the total Dutch consumption of prescribed pharmaceuticals in 2007. Calculations based on a fixed consumption rate (2007) predict that demographic developments can be expected to push consumption up to 1.504 metric tonnes in 2020 (+17%) and 1.851 metric tonnes by 2050 (+37%). Therapeutic groups showing the largest increase are related to illnesses associated with old age. The only groups showing a decrease are the antivirals and drugs for addiction treatments as well as ethinylestradiol, an active compound in contraceptives.

Airflow limitation during respiratory syncytial virus lower respiratory tract infection predicts recurrent wheezing.

BACKGROUND: Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is frequently followed by recurrent wheezing. Thus far no clinical risk factors have been identified to predict which infants will have wheezing episodes subsequent to RSV LRTI. OBJECTIVE: To determine clinical predictors for airway morbidity after RSV LRTI. METHODS: In a 1-year follow-up study we investigated the predictive value of auscultatory findings characteristic of airflow limitation (wheezing) during RSV LRTI for subsequent airway morbidity. Clinical characteristics, including the presence or absence of signs of airflow limitation, of hospitalized infants with RSV LRTI were prospectively recorded during 2 winter epidemics. During a 1-year follow-up period parents of 130 infants recorded daily airway symptoms. OUTCOME MEASURE: Recurrent wheezing defined as > or = 2 episodes of wheezing. RESULTS: Signs of airflow limitation during RSV LRTI were absent in 47 (36%) infants and present in 83 (64%) infants. Recurrent wheezing was recorded in 10 (21%) infants without signs of airflow limitation and in 51 (61%) with signs of airflow limitation during initial RSV LRTI (relative risk, 0.29, P < 0.001). In a multiple logistic regression model, airflow limitation during initial RSV LRTI proved independent from other clinical parameters, including age, parental history of asthma and smoke exposure. CONCLUSIONS: A sign of airflow limitation during RSV LRTI is the first useful clinical predictor for subsequent recurrent wheezing.

Balancing the risks and benefits of drinking water disinfection: disability adjusted life-years on the scale.

To evaluate the applicability of disability adjusted life-years (DALYs) as a measure to compare positive and negative health effects of drinking water disinfection, we conducted a case study involving a hypothetical drinking water supply from surface water. This drinking water supply is typical in The Netherlands. We compared the reduction of the risk of infection with Cryptosporidium parvum by ozonation of water to the concomitant increase in risk of renal cell cancer arising from the production of bromate. We applied clinical, epidemiologic, and toxicologic data on morbidity and mortality to calculate the net health benefit in DALYs. We estimated the median risk of infection with C. parvum as 10(-3)/person-year. Ozonation reduces the median risk in the baseline approximately 7-fold, but bromate is produced in a concentration above current guideline levels. However, the health benefits of preventing gastroenteritis in the general population and premature death in patients with acquired immunodeficiency syndrome outweigh health losses by premature death from renal cell cancer by a factor of > 10. The net benefit is approximately 1 DALY/million person-years. The application of DALYs in principle allows us to more explicitly compare the public health risks and benefits of different management options. In practice, the application of DALYs may be hampered by the substantial degree of uncertainty, as is typical for risk assessment.

The presence of Aeromonas in drinking water supplies in The Netherlands.

The occurrence of Aeromonas in raw, treated and distributed waters of 20 different treatment stations in the Netherlands was studied over a one-and-a-half year period. River water yielded highest numbers (greater than 10,000 cfu/100 ml) of predominantly anaerogenic strains. In open storage reservoirs for river water or dune infiltrate, numbers were usually between 1,000 and 10,000/100 ml with a majority of aerogenic strains, in particular A. sobria. River water after dune infiltration or pure dune water, collected in closed systems, as well as aerobic or anaerobic groundwater, were usually free of Aeromonas in 100 ml. Treated waters showed low counts (usually less than 10 cfu/100 ml), irrespective of raw water source. Regrowth of aeromonads occurred in 16 out of 20 distribution systems examined. Geometric means counts (2nd half of 1986) in these systems varied between 1 and 440 cfu/100 ml and maximum counts between 10 and 3300 cfu/100 ml. Aeromonas-densities were related to temperature and residence time, but not to total organic matter or heterotrophic plate counts. Regrowth occurred particularly in drinking water derived from anaerobic groundwater containing methane. A. hydrophila was the most frequently isolated species from distribution waters, but A. caviae and A. sobria were predominant in a few systems.

Complexing of copper in drinking water samples to enhance recovery of Aeromonas and other bacteria.

The presence of copper in drinking water samples at concentrations as low as 10 micrograms/l resulted in a rapid die-off of aeromonads. Coliform bacteria, heterotrophic plate count bacteria and faecal streptococci were also sensitive to copper but to a lesser degree than aeromonads. The effect was particularly noticeable in soft water (less than 3 meq/l Ca + Mg) and at pH-values below 8.0. The toxic effect of copper concentrations up to 500 micrograms/l could be neutralized for a period of up to 24 h by the addition to samples of 50 mg/l of disodium-ethylene-diamino-tetraacetate (Na2EDTA) and keeping the samples on melting ice.

Ampicillin-dextrin agar medium for the enumeration of Aeromonas species in water by membrane filtration.

Published selective media were evaluated for the isolation of Aeromonas spp. from environmental samples by membrane filtration. Satisfactory recoveries were obtained only with mA agar (Rippey & Cabelli) and dextrin-fuchsin-sulphite agar (Schubert), but neither was sufficiently selective. The positive aspects of these two media were combined in a new medium, ampicillin-dextrin agar. Recovery from pure cultures and environmental samples was optimal at an ampicillin concentration of 10 mg/l and incubation for 24 h at 30 degrees C under aerobic conditions, and specificity was high (i.e. confirmation rate usually greater than 90%, no false negative colonies encountered). The medium can also be used for isolation of Aeromonas spp. from sea water provided that the vibriostatic agent 0/129 is added at 50 mg/l.

Kinetics of the formation and secretion of the aniline metabolite 4-aminophenol and its conjugates by isolated rat hepatocytes.

The rates of secretion of 4-aminophenol and its sulphate and glucuronide conjugate were determined in cultures of rat hepatocytes with aniline and 4-aminophenol as substrates. When 4-aminophenol (300 microM) was used as substrate, 4-aminophenol disappeared from the medium within 30 min. Secretion of conjugates continued for more than 60 min, when 70% of the 4-aminophenol had been secreted as conjugates. At a low concn. of 4-aminophenol, the sulphate ester was the main metabolite, while secretion of the glucuronide showed a more than proportional rise ('lag phase') with increasing substrate concn. At higher concn. (greater than 300 microM) about equal amounts of both conjugates were formed. Without inorganic sulphate, sulphation of 4-aminophenol was greatly diminished and the lag phase in glucuronide secretion was not found. With 1 mM aniline as substrate up to 300 microM of conjugated 4-aminophenol was secreted with a linear time-dependence for at least two hours. With aniline as substrate the sulphate ester was the most important conjugate and lag phases in the secretion of both conjugates were minimal. Phenobarbitone pretreatment in vivo stimulated the secretion of conjugated products after incubation with aniline. No dramatic changes in the profile of the lag phases were seen. The differences in the conjugation profiles of both substrates can be explained by taking into consideration the differences in the expected intracellular concentrations.

Measurement of SCE frequencies in plants: a simple Feulgen-staining procedure for vicia faba.

A relatively straightforward approach is described to obtain differential contrast in sister chromatids for SCE detection in Vicia faba after BrdUrd incorporation. The hydrolysis time of the well-known Feulgen reaction was extended to differentially degrade the DNA, the BrdUrd-substituted strands being more resistant. The procedure may easily be adapted for other plant species with large chromosomes.