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.

Indirect vs direct assessment of gastric emptying: A randomized crossover trial comparing C-isotope breath analysis and MRI.

BACKGROUND: Indirect methods to assess gastric emptying (GE), such as 13 C breath tests (BT), are commonly used. However, BT usually use a sampling time of 4+ hours. The current study aims to assess the validity of BT for four liquid meals differing in physicochemical properties. To this aim, we compared them to MRI GE-measurements. METHODS: Fifteen healthy males (age 22.6 ± 2.4 years, BMI 22.6 ± 1.8 kg/m2 ) participated in a randomized 2 × 2 crossover experiment. Test foods were liquid meals, which were either thin/thick and 100/500 kcal, labeled with 100 mg of 13 C-octanoate. GE was measured with MRI and assessed by 13 C recovery from breath. Participants were scanned every 10 minutes and at six time points breath samples were collected up to t = 90 minutes. Two curves were fitted to the data to estimate emptying halftime (t50 Ghoos and t50 Bluck ). T50 times were ranked per participant and compared between methods. KEY RESULTS: On average, MRI and BT showed similar t50 rankings for the four liquid meals. In comparison to MRI, t50 Ghoos overestimated, while t50 Bluck underestimated GE time. Moreover, more viscous foods were overestimated. In most participants individual t50 time rankings differed significantly between methods. CONCLUSIONS & INFERENCES: BT can assess relative emptying differences on group level and collecting breath data for 90 minutes constitutes a lower burden for participants and the research facility. However, BT has severe shortcomings compared to MRI for individual GE assessment. Notably, food matrix effects should be considered when interpreting the results of BT.

γ-H2AX foci as in vivo effect biomarker in children emphasize the importance to minimize x-ray doses in paediatric CT imaging.

OBJECTIVES: Investigation of DNA damage induced by CT x-rays in paediatric patients versus patient dose in a multicentre setting. METHODS: From 51 paediatric patients (median age, 3.8 years) who underwent an abdomen or chest CT examination in one of the five participating radiology departments, blood samples were taken before and shortly after the examination. DNA damage was estimated by scoring γ-H2AX foci in peripheral blood T lymphocytes. Patient-specific organ and tissue doses were calculated with a validated Monte Carlo program. Individual lifetime attributable risks (LAR) for cancer incidence and mortality were estimated according to the BEIR VII risk models. RESULTS: Despite the low CT doses, a median increase of 0.13 γ-H2AX foci/cell was observed. Plotting the induced γ-H2AX foci versus blood dose indicated a low-dose hypersensitivity, supported also by an in vitro dose-response study. Differences in dose levels between radiology centres were reflected in differences in DNA damage. LAR of cancer mortality for the paediatric chest CT and abdomen CT cohort was 0.08 and 0.13 ‰ respectively. CONCLUSION: CT x-rays induce DNA damage in paediatric patients even at low doses and the level of DNA damage is reduced by application of more effective CT dose reduction techniques and paediatric protocols. .

Standardized added metabolic activity (SAM) IN ¹8F-FDG PET assessment of treatment response in colorectal liver metastases.

PURPOSE: Standardized added metabolic activity (SAM) is a PET parameter for assessing the total metabolic load of malignant processes, avoiding partial volume effects and lesion segmentation. The potential role of this parameter in the assessment of response to chemotherapy and bevacizumab was tested in patients with metastatic colorectal cancer with potentially resectable liver metastases (mCRC). METHODS: (18)F-FDG PET/CT was performed in 18 mCRC patients with liver metastases before treatment and after five cycles of FOLFOX/FOLFIRI and bevacizumab. Of the 18 patients, 16 subsequently underwent resection of liver metastases. Baseline and follow-up SUVmax, and SAM as well as reduction in SUVmax (∆SUVmax) and SAM (∆SAM) of all liver metastases were correlated with morphological response, and progression-free and overall survival (PFS and OS). RESULTS: A significant reduction in metabolic activity of the liver metastases was seen after chemotherapy with a median ∆SUVmax of 25.3% and ∆SAM of 94.5% (p = 0.033 and 0.003). Median baseline SUVmax and SAM values were significantly different between morphological responders and nonresponders (3.8 vs. 7.2, p = 0.021; and 34 vs. 211, p = 0.002, respectively), but neither baseline PET parameters nor morphological response was correlated with PFS or OS. Follow-up SUVmax and SAM as well as ∆SAM were found to be prognostic factors. The median PFS and OS in the patient group with a high follow-up SUVmax were 10.4 months and 32 months, compared to a median PFS of 14.7 months and a median OS which had not been reached in the group with a low follow-up SUVmax (p = 0.01 and 0.003, respectively). The patient group with a high follow-up SAM and a low ∆SAM had a median PFS and OS of 9.4 months and 32 months, whereas the other group had a median PFS of 14.7 months and a median OS which had not been reached (p = 0.002 for both PFS and OS). CONCLUSION: (18)F-FDG PET imaging is a useful tool to assess treatment response and predict clinical outcome in patients with mCRC who undergo chemotherapy before liver metastasectomy. Follow-up SUVmax, follow-up SAM and ∆SAM were found to be significant prognostic factors for PFS and OS.

Practical applications of quantitative microbial risk assessment (QMRA) for water safety plans.

The absence of indicator organisms in drinking water does not provide sufficient guarantee for microbial safety. Therefore the water utilities are implementing water safety plans (WSP) to safeguard drinking water quality. Quantitative microbial risk assessment (QMRA) can be used to provide objective quantitative input for the WSP. This study presents several applications of treatment modelling in QMRA to answer the risk managers questions raised in the WSP. QMRA can estimate how safe the water is, how much the safety varies and how certain the estimate of safety is. This can be used in the WSP system assessment to determine whether treatment is meeting health-based targets with the required level of certainty. Quantitative data analysis showed that short events of only 8 hours per year can dominate the yearly average health risk for the consumer. QMRA also helps the design of physical and microbial monitoring. The study showed that the required monitoring frequency increases with increasing treatment efficacy. Daily monitoring can be sufficient to verify a treatment process achieving 2 log reduction of pathogens, but a process achieving 4 log reduction needs to be monitored every 15 minutes. Similarly, QMRA helps to prepare adequate corrective actions by determining the acceptable 'down time' of a process. For example, for a process achieving 2.5 log reduction a down time of maximum 6 hours per year is acceptable. These applications illustrate how QMRA can contribute to efficient and effective management of microbial drinking water safety.

Improved methods for modelling drinking water treatment in quantitative microbial risk assessment; a case study of Campylobacter reduction by filtration and ozonation.

Quantitative microbial risk assessment (QMRA) is increasingly applied to estimate drinking water safety. In QMRA the risk of infection is calculated from pathogen concentrations in drinking water, water consumption and dose response relations. Pathogen concentrations in drinking water are generally low and monitoring provides little information for QMRA. Therefore pathogen concentrations are monitored in the raw water and reduction of pathogens by treatment is modelled stochastically with Monte Carlo simulations. The method was tested in a case study with Campylobacter monitoring data of rapid sand filtration and ozonation processes. This study showed that the currently applied method did not predict the monitoring data used for validation. Consequently the risk of infection was over estimated by one order of magnitude. An improved method for model validation was developed. It combines non-parametric bootstrapping with statistical extrapolation to rare events. Evaluation of the treatment model was improved by presenting monitoring data and modelling results in CCDF graphs, which focus on the occurrence of rare events. Apart from calculating the yearly average risk of infection, the model results were presented in FN curves. This allowed for evaluation of both the distribution of risk and the uncertainty associated with the assessment.

How can the UK statutory Cryptosporidium monitoring be used for Quantitative Risk Assessment of Cryptosporidium in drinking water?

Quantitative Microbiological Risk Assessment (QMRA) is increasingly being used to complement traditional verification of drinking water safety through the absence of indicator bacteria. However, the full benefit of QMRA is often not achieved because of a lack of appropriate data on the fate and behaviour of pathogens. In the UK, statutory monitoring for Cryptosporidium has provided a unique dataset of pathogens directly measured in large volumes of treated drinking water. Using this data a QMRA was performed to determine the benefits and limitations of such state-of-the-art monitoring for risk assessment. Estimates of the risk of infection at the 216 assessed treatment sites ranged from 10(-6.5) to 10(-2.5) person(-1) d(-1). In addition, Cryptosporidium monitoring data in source water was collected at eight treatment sites to determine how Cryptosporidium removal could be quantified for QMRA purposes. Cryptosporidium removal varied from 1.8 to 5.2 log units and appeared to be related to source water Cryptosporidium concentration. Application of general removal credits can either over- or underestimate Cryptosporidium removal by full-scale sedimentation and filtration. State-of-the-art pathogen monitoring can identify poorly performing systems, although it is ineffective to verify drinking water safety to the level of 10(-4) infections person(-1) yr(-1).

A classical conditioning procedure for the hearing assessment of multiply handicapped persons.

The present study evaluated the viability of a classical conditioning procedure with an air puff as unconditioned stimulus for the hearing assessment of multiply handicapped children and adolescents. All subjects were also exposed to operant conditioning, which consisted of a modified visual reinforcement audiometry (VRA) procedure or involved edible reinforcement contingent on a reaching response (for blind subjects). The findings indicate that the classical conditioning procedure was successful with 21 of the 23 subjects, whereas operant conditioning succeeded with 15 of the subjects. Thresholds obtained with classical conditioning were mostly equal to or within 10 dB of those obtained with operant conditioning and also matched previously available hearing estimates. These findings seem to suggest that the classical procedure can be a useful behavioral alternative for audiological assessment.

Traumatic lumbosacral nerve root meningoceles. The value of myelography, CT and MRI in the assessment of nerve root continuity.

A case of traumatic lumbar meningoceles at four levels in combination with total and partial nerve root avulsion and with preservation of a nerve root is reported. Several diagnostic imaging techniques (myelography, CT, myelo-CT and MRI) are compared and their value in demonstrating the continuity of the nerve roots is discussed. MRI could assess the continuity of a nerve root in a traumatic meningocele, not demonstrable by myelography or myelo-CT. The combination of myelography, myelo-CT and MRI is likely to provide a complete diagnostic evaluation of nerve root lesions.

Hearing assessment in developmentally impaired infants: classical conditioning as a supplement to brainstem-evoked response audiometry (BERA).

The brainstem-evoked response audiometry (BERA) is probably the most common approach to hearing assessment in high-risk and developmentally handicapped infants. It is usually suggested, however, that BERA should not be the sole assessment method. In an attempt to determine an effective supplement to BERA, the present study evaluated a classical conditioning procedure with developmentally impaired babies. Within this procedure, different tones served as conditioned stimuli while an air-puff was used as the unconditioned stimulus. Results indicate that this procedure could be successfully applied with almost all of the babies.