Understanding the mechanisms linking holistic housing renovations to health and well-being of adults in disadvantaged neighbourhoods: A realist review.

Holistic housing renovations combine physical housing improvements with social and socioeconomic interventions (e.g. referral to social services, debt counselling, involvement in decision-making, promoting social cohesion). This realist review aimed at understanding underlying mechanisms linking holistic housing renovations to health and well-being of adults in disadvantaged neighbourhoods. Following systematic and iterative searching, and relevance and quality appraisals, 18 scientific articles and reports were analysed. We identified three pathways via which physical housing improvements affect health, four pathways via which social and socioeconomic interventions affect health, and two pathways via which both reinforce each other in their health effects. Our findings are theoretically novel, relevant for those conducting holistic housing renovations, and point towards gaps in the literature.

Knowledge of diagnosis and management of selected oral mucosal lesions among dentists in The Netherlands.

BACKGROUND: Knowledge of oral mucosal lesions (OMLs) among dentists is relevant in diagnosing potentially malignant diseases and oral cancer at an early stage. The aim of this survey was to explore dentists' knowledge about OMLs. MATERIAL AND METHODS: Respondents to a web-based questionnaire, containing 11 clinical vignettes representing patients with various OMLs, provided a (differential) diagnosis and management for each. Information about demographics and clinical experience of the participants was acquired as well. Descriptive statistics were performed and T-tests were used to test for significant (p<0.05) differences in mean scores for correct diagnosis and management between subgroups based on demographic variables. RESULTS: Forty-four of 500 invited dentists completed the questionnaire. For (potentially) malignant OMLs, the number of correct diagnoses ranged from 14 to 93%, whilst the number of correct management decisions ranged from 43 to 86%. For benign OMLs, the number of correct diagnoses and management decisions ranged from 32 to 100% and 9 to 48%, respectively. For 11 clinical vignettes, mean scores for correct diagnosis, correct management and correct diagnosis and management were respectively 7.2 (±1.8), 5.7 (±1.5), and 3.8 (±1.7). CONCLUSIONS: The results show that dentists in the Netherlands do not have sufficient knowledge to accurately diagnose some OMLs and to select a correct management. This may result in over-referral of benign OMLs and under-referral for (potentially) malignant OMLs. Clinical guidelines, that include standardized criteria for referral, and continuing education, may improve dentists' ability to correctly diagnose and accurately manage OMLs.

[Human papillomavirus vaccination available for boys also; information for oral healthcare providers]. / Humaan papillomavirus-vaccinatie nu ook beschikbaar voor jongens: informatie voor mondzorgverleners.

Recently, the Dutch National Immunization Programme has started to offer the human papillomavirus (HPV) vaccination to boys as well as girls from the age of 10. The vaccine protects against long-term HPV infection, which can lead to cervical, anogenital and oropharyngeal cancer. Besides malignant disorders, a HPV infection can also lead to certain disorders of the skin and oral cavity. Since the national HPV vaccination campaign has probably resulted in more awareness among patients about the relation between HPV and oropharyngeal cancer, patients may consult oral healthcare professionals with questions about HPV infection. Oral healthcare professionals are thus able to play a role in preventing HPV related disorders by counseling their patients on HPV. They can also contribute to early diagnosis of HPV related oral and oropharyngeal disorder, although the possibility of detecting oropharyngeal cancer during routine dental examination  is limited.

[Knowledge of Dutch dentists regarding HPV associated cancer of the oropharynx]. / Kennis van Nederlandse tandartsen over orofarynxkanker veroorzaakt door het humaan papillomavirus.

Worldwide and also in the Netherlands there is an increasing human papillomavirus (HPV)-attributable oropharyngeal cancer incidence. This type of cancer is more common at a younger age than the classical oropharyngeal cancer, which is usually caused by smoking and excessive drinking. Most often, the tumor occurs in the tonsils and at the base of the tongue. This study explored the level of knowledge of dentists about oropharyngeal cancer, its association with the human papillomavirus and their willingness to play a role in prevention. 7.364 digital questionnaires were sent to oral health-care providers and data from 607 dentists was analyzed. 48% of knowledge questions were answered correctly by more than half of the respondents. Significantly more female caregivers were aware of the relationship between HPV and oropharyngeal cancer and the availability of an HPV vaccine. Respondents considered it important that the relationship between HPV and oropharyngeal cancer is discussed with patients and that a protocol is developed that is useful in screening for mouth and throat cancer.

Patient-reported outcomes after incisional hernia repair.

PURPOSE: Patient-reported outcomes (PROs) are pivotal to evaluate the efficacy of surgical management. Debate persists on the optimal surgical technique to repair incisional hernias. Assessment of PROs can guide the selection of the best management of patients with incisional hernias. The objective of this cohort study was to present the PROs after incisional hernia repair at long term follow-up. METHODS: Patients with a history of incisional hernia repair were seen at the out-patient clinic to collect PROs. Patients were asked about the preoperative indication for repair and postoperative symptoms, such as pain, feelings of discomfort, and bulging of the abdominal wall. Additionally, degree of satisfaction was asked and Carolina Comfort Scales were completed. RESULTS: Two hundred and ten patients after incisional hernia repair were included with a median follow-up of 3.2 years. The main indication for incisional hernia repair was the presence of a bulge (60%). Other main reasons for repair were pain (19%) or discomfort (5%). One hundred and thirty-two patients (63%) reported that the overall status of their abdominal wall had improved after the operation. Postoperative symptoms were reported by 133 patients (63%), such as feelings of discomfort, pain and bulging. Twenty percent of patients reported that the overall status of their abdominal wall was the same, and 17% reported a worse status, compared to before the operation. Ten percent of the patients would not opt for operation in hindsight. CONCLUSION: This study showed that a majority of the patients after incisional hernia repair still report pain or symptoms such as feelings of discomfort, pain, and bulging of the abdominal wall 3 years after surgery. Embedding patients' expectations and PROs in the preoperative counseling discussion is needed to improve decision-making in incisional hernia surgery.

Tranexamic acid therapy for postoperative bleeding after bariatric surgery.

BACKGROUND: Tranexamic acid reduces blood loss associated with various surgical procedures. Postoperative bleeding caused by dissection or bleeding of the enteric staple lines is a well-known complication following bariatric surgery. Reoperation in order to restore hemostasis is frequently necessary (up to 2.5% in literature). The effect of conservative therapy using tranexamic acid for postoperative hemorrhage after bariatric surgery is still very much a novel technique. The aim is to present our results (reoperation rate and thrombo-embolic complication rate) of tranexamic acid therapy for postoperative bleeding after bariatric surgery in comparison to those in existing literature. METHODS: We retrospectively reviewed 1388 patients who underwent bariatric surgery (laparoscopic gastric bypass or laparoscopic gastric sleeve). Use of tranexamic acid, reoperation rate, transfusion rate and rate of thrombo-embolic complications were reviewed. RESULTS: Forty-five of 1388 (3.2%) total patients experienced significant hemorrhage after bariatric surgery. Tranexamic acid was administered in 44 of these patients. A failure of the treatment with tranexamic acid was observed in four patients. The incidence of reoperation was 0.4% for the entire population. No thrombo-embolic complications were registered for patients receiving tranexamic acid. CONCLUSION: These findings suggest that the administration of tranexamic acid appears to be safe in reducing the reoperation rate for bleeding after bariatric surgery.

Development of the 'Canteen Scan': an online tool to monitor implementation of healthy canteen guidelines.

BACKGROUND: To improve the availability and accessibility of healthier food and drinks in schools, sports and worksites canteens, national Guidelines for Healthier Canteens were developed by the Netherlands Nutrition Centre. Until now, no tool was available to monitor implementation of these guidelines. This study developed and assessed the content validity and usability of an online tool (the 'Canteen Scan') that provides insight into and directions for improvement of healthier food products in canteens. METHODS: The Canteen Scan was developed using a three-step iterative process. First, preliminary measures and items to evaluate adherence to the guidelines were developed based on literature, and on discussions and pre-tests with end-users and experts from science, policy and practice. Second, content validity of a paper version of the Canteen Scan was assessed among five end-users. Third, the online Canteen Scan was pilot tested among end-users representing school canteens. Usability was measured by comprehensibility, user-friendliness, feasibility, time investment, and satisfaction. RESULTS: The content validity of the Canteen Scan was ensured by reaching agreement between stakeholders representing science, policy and practice. The scan consists of five elements: 1) basic conditions (e.g. encouragement to drink water and availability of policy regarding the guidelines), 2) product availability offered on displays (counter, shelf) and 3) in vending machines, 4) product accessibility (e.g. promotion and placement of products), and 5) an overall score based on the former elements and tailored feedback for creating a healthier canteen. The scan automatically classifies products into healthier or less healthy products. Pilot tests indicated good usability of the tool, with mean scores of 4.0-4.6 (5-point Likert scale) on the concepts comprehensibility, user-friendliness and feasibility. CONCLUSION: The Canteen Scan provides insight into the extent to which canteens meet the Dutch Guidelines for Healthier Canteens. It also provides tailored feedback to support adjustments towards a healthier canteen and with the scan changes over time can be monitored. Pilot tests show this tool to be usable in practice.

Controversies in laparoscopic ventral hernia repair.

The introduction of laparoscopy as a surgical technique provided a method which allows for preventing major abdominal wall incisions and improving recovery of the patient after surgery. In abdominal wall surgery, laparoscopic ventral hernia repair has proven to be at least as safe as open repair. However, the technique of laparoscopic ventral hernia repair has not been standardized. Despite all the research that has been conducted and all the articles that have been published, there still seems to be a lack of consensus about the best method to repair a ventral hernia. The aim of this paper is to review knowledge on incisional hernias and discuss several controversies regarding the laparoscopic management of ventral hernias. A review of the literature was undertaken, and a search identified twenty records: six RCTs on incisional hernias, five RCTs on ventral hernias, and nine reviews or meta-analyses. Interpretation of the scientific data was difficult because the outcomes in literature were often based on pooled data of primary ventral hernias and incisional ventral hernias. Controversy remains regarding the optimal laparoscopic management of ventral hernias in terms of selection of patients for laparoscopic repair, optimal technique, outcomes and cost-efficacy. Lack of evidence allows persisting controversies in laparoscopic ventral hernia repair. RCTs and registries are necessary to document efficacy, morbidity, quality of life and costs during a sufficient period of time to provide clinicians with the evidence required to make the right choice for the best surgical technique.

Controversies in laparoscopic ventral hernia repair.

BACKGROUND: The introduction of laparoscopy as a surgical technique provided a method preventing major abdominal wall incisions and improving recovery of the patient after surgery. In abdominal wall surgery laparoscopic ventral hernia repair has proven to be at least as save as open repair. However, the technique of laparoscopic ventral hernia repair has not been standardized. Despite all the research that has been conducted and all the articles that were published, there still seems to be absence of consensus about the best method to repair a ventral hernia. AIM: To review knowledge on incisional hernias and discuss several controversies regarding the laparoscopic management of ventral hernias. METHODS: A review of the literature was undertaken. RESULTS: A search identified twenty records: six RCTs on incisional hernias, five RCTs on ventral hernias and nine reviews or meta-analyses. Interpretation of the scientific data is difficult because the outcomes in literature are often based on pooled data of primary ventral hernias and incisional ventral hernias. Controversy remains regarding the optimal laparoscopic management of ventral hernias in terms of selection of patients for laparoscopic repair, optimal technique, outcomes and cost-efficacy. CONCLUSION: Lack of evidence allows persisting controversies in laparoscopic ventral hernia repair. RCTs and registries are necessary to document efficacy, morbidity, quality of life and costs during a sufficient period of time to provide clinicians with the evidence required to make the right choice for the best surgical technique.

Extensive cervicomediastinal hematoma due to spontaneous hemorrhage of a parathyroid adenoma: a case report.

Spontaneous extracapsular hemorrhage is a rare but potentially life-threatening manifestation of parathyroid gland adenomas. We present a case demonstrating that even in a patient with increased bleeding tendency due to anticoagulants, combined with compression of trachea and esophagus, conservative treatment can be successful.

Economic values of growth and feed efficiency for fish farming in recirculating aquaculture system with density and nitrogen output limitations: a case study with African catfish (Clarias gariepinus).

In fish farming, economic values (EV) of breeding goal traits are lacking, even though they are key parameters when defining selection objectives. The aim of this study was to develop a bioeconomic model to estimate EV of 2 traits representing production performances in fish farming: the thermal growth coefficient (TGC) and the feed conversion ratio (FCR). This approach was applied to a farm producing African catfish (Clarias gariepinus) in a recirculating aquaculture system (RAS). In the RAS, 2 factors could limit production level: the nitrogen treatment capacity of the biofilter or the fish density in rearing tanks at harvest. Profit calculation includes revenue from fish sales, cost of juveniles, cost of feed, cost of waste water treatment, and fixed costs. In the reference scenario, profit was modeled to zero. EV were calculated as the difference in profit per kilogram of fish between the current population mean for both traits (µt) and the next generation of selective breeding (µt+Δt) for either TGC or FCR. EV of TGC and FCR were calculated for three generations of hypothetical selection on either TGC or FCR (respectively 6.8% and 7.6% improvement per generation). The results show that changes in TGC and FCR can affect both the number of fish that can be stocked (number of batches per year and number of fish per batch) and the factor limiting production. The EV of TGC and FCR vary and depend on the limiting factors. When dissolved NH3-N is the limiting factor for both µt and µt+Δt, increasing TGC decreases the number of fish that can be stocked but increases the number of batches that can be grown. As a result, profit remains constant and EVTGC is zero. Increasing FCR, however, increases the number of fish stocked and the ratio of fish produced per kilogram of feed consumed ("economic efficiency"). The EVFCR is 0.14 €/kg of fish, and profit per kilogram of fish increases by about 10%. When density is the limiting factor for both µt and µt+Δt, the number of fish stocked per batch is fixed; therefore, extra profit is obtained by increasing either TGC, which increases the annual number of batches, or by decreasing FCR, which decreases annual feed consumption. EVTGC is 0.03 €/kg of fish and EVFCR is 0.05-0.06 €/kg of fish. These results emphasize the importance of calculating economic values in the right context to develop efficient future breeding programs in aquaculture.

Small, medium, large or supersize? The development and evaluation of interventions targeted at portion size.

In the past decades, portion sizes of high-caloric foods and drinks have increased and can be considered an important environmental obesogenic factor. This paper describes a research project in which the feasibility and effectiveness of environmental interventions targeted at portion size was evaluated. The studies that we conducted revealed that portion size labeling, offering a larger variety of portion sizes, and proportional pricing (that is, a comparable price per unit regardless of the size) were considered feasible to implement according to both consumers and point-of-purchase representatives. Studies into the effectiveness of these interventions demonstrated that the impact of portion size labeling on the (intended) consumption of soft drinks was, at most, modest. Furthermore, the introduction of smaller portion sizes of hot meals in worksite cafeterias in addition to the existing size stimulated a moderate number of consumers to replace their large meals by a small meal. Elaborating on these findings, we advocate further research into communication and marketing strategies related to portion size interventions; the development of environmental portion size interventions as well as educational interventions that improve people's ability to deal with a 'super-sized' environment; the implementation of regulation with respect to portion size labeling, and the use of nudges to stimulate consumers to select healthier portion sizes.

Comparison of the Dutch and English versions of the Carolinas Comfort Scale: a specific quality-of-life questionnaire for abdominal hernia repairs with mesh.

PURPOSE: Repair of abdominal wall hernias with mesh is one of the most common procedures in general surgery. The introduction of hernia repair with mesh has lowered recurrence rates and shifted the focus to quality of life after surgery, raising the need for a specific tool measuring quality of life. The Carolinas Comfort Scale (CCS) is a questionnaire designed specifically for patients having hernia repair with mesh. The aim of this study is to validate the Dutch CCS and to compare it to the generic short form-36 (SF-36). METHODS: The CCS questionnaire was translated into Dutch. Patients undergoing mesh hernia repair between April 2010 and December 2011 completed the CCS, the SF-36 and four questions comparing these two questionnaires in the first week after surgery. After 3 weeks, the CCS was repeated. Correlations between the two surveys were calculated using the Spearman's rank correlation test with a 95 % confidence interval to determine validity. RESULTS: The response rate was 60.3 % (100/168). The CCS showed excellent reliability with a Cronbach's α of 0.948. Significant correlation existed between the CCS and the domains physical functioning, bodily pain, role-physical, vitality and social functioning of the SF-36. Seventy-nine percent of the patients preferred the CCS to the SF-36, and 83 % considered the CCS a better reflection of their quality of life after hernia repair with mesh. CONCLUSION: The Dutch CCS appears a valid and clinically relevant tool for assessing quality of life after repair of abdominal wall hernia with mesh.

Fish welfare assurance system: initial steps to set up an effective tool to safeguard and monitor farmed fish welfare at a company level.

The objective was to take a first step in the development of a process-oriented quality assurance (QA) system for monitoring and safeguarding of fish welfare at a company level. A process-oriented approach is focused on preventing hazards and involves establishment of critical steps in a process that requires careful control. The seven principles of the Hazard Analysis Critical Control Points (HACCP) concept were used as a framework to establish the QA system. HACCP is an internationally agreed approach for management of food safety, which was adapted for the purpose of safeguarding and monitoring the welfare of farmed fish. As the main focus of this QA system is farmed fish welfare assurance at a company level, it was named Fish Welfare Assurance System (FWAS). In this paper we present the initial steps of setting up FWAS for on growing of sea bass (Dicentrarchus labrax), carp (Cyprinus carpio) and European eel (Anguilla anguilla). Four major hazards were selected, which were fish species dependent. Critical Control Points (CCPs) that need to be controlled to minimize or avoid the four hazards are presented. For FWAS, monitoring of CCPs at a farm level is essential. For monitoring purposes, Operational Welfare Indicators (OWIs) are needed to establish whether critical biotic, abiotic, managerial and environmental factors are controlled. For the OWIs we present critical limits/target values. A critical limit is the maximum or minimum value to which a factor must be controlled at a critical control point to prevent, eliminate or reduce a hazard to an acceptable level. For managerial factors target levels are more appropriate than critical limits. Regarding the international trade of farmed fish products, we propose that FWAS needs to be standardized in aquaculture chains. For this standardization a consensus on the concept of fish welfare, methods to assess welfare objectively and knowledge on the needs of farmed fish are required.

Monitoring phytoplankton and marine biotoxins in production waters of the Netherlands: results after one decade.

Shellfish products may be contaminated with marine biotoxins which, after consumption, may lead to human illness. The Netherlands has a regular monitoring programme for marine biotoxins and the possible toxic phytoplankton in shellfish production waters. The aim of the current study was to evaluate the presence of potential toxic phytoplankton species and marine biotoxins in Dutch production waters over the last decade, and to analyse the relationship between toxin levels and abundance of possible causative phytoplankton species. The results of the monitoring programme of the period 1999-2009 were used. The presence of Alexandrium spp. were negligible, but Pseudo-nitzschia spp. and phytoplankton causing diarrhetic shellfish poisoning (DSP toxin-producing phytoplankton) were present in nearly all three main production areas and years. The main DSP toxin-producing species was Dinophysis acuminata followed by D. rotundata and Prorocentrum lima. Toxins causing paralytic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP) were present in only a few individual shellfish samples, all at low levels. At the end of 2002, an episode of DSP toxicity was recorded, based on the rat bioassay results. Of the samples that were chemically analysed for DSP toxins in 2007 and 2008, about half of the samples in 2007 contained these toxins, although levels were low and no positive results were obtained using the rat bioassay. There was a slight positive correlation between concentrations of DSP toxin-producing phytoplankton and levels of DSP toxins in 2007. Increased DSP toxin levels were found up to 5 weeks after the peak in DSP toxin-producing phytoplankton. This positive, but weak, relationship needs to be confirmed in future research using more samples and chemical methods to quantify the presence of DSP toxins. If this relationship is further substantiated and quantified, it could be used within the current monitoring programme in the Netherlands to predict the risk areas regarding DSP toxicity in shellfish.

Modified onlay technique for the repair of the more complicated incisional hernias: single-centre evaluation of a large cohort.

BACKGROUND: The repair of incisional hernias remains a challenge for the general surgeon. Indications for surgery are severe bowel obstruction, as well as aesthetic problems. There are various surgical methods to correct these hernias, with varying results. However, the gold standard has not yet been found. Both laparoscopic repair and the component separation technique (CTS) have proven to be acceptable techniques; however, they are not always suitable for resolving the more complicated abdominal wall defects, i.e. after open-abdomen treatment or fascial necrosis. In our hospital, we developed a new onlay technique which we have evaluated in the following research. PATIENTS AND METHODS: During a period of 10 years (1996-2007), 101 patients with an incisional hernia were corrected with the new onlay technique. A Marlex mesh of dimensions at least 10 x 20 cm was used, overlapping the fascia by at least 5 cm on each side. This mesh was stapled onto the fascia with skin staples. Of the 101 patients, there were 45 men and 56 women, with a mean age of 55 years. Nine patients died and 13 were lost during follow-up. Of the remaining 79 patients, eight refused to participate. The mean follow-up time was 64 months (normal distribution, standard deviation [SD] 34 months). This cohort of 101 patients was studied retrospectively. RESULTS: Seventy-one of the 101 patients were evaluated at our out-patient clinic. For 24 patients (25%), the operation was for a recurrence after an incisional hernia correction in the past. Twenty-one patients (20%) had an open-abdomen treatment in their medical history. The surgical procedure was technically possible in all patients and the mean operation time was 63 min. The median admission time was 4.5 days (quartiles 3-6.25). The mean follow-up time was 64 months (SD 35 months). A seroma was reported in 27 of 101 patients (27%) and a wound infection in 22 patients (21%), of which seven patients had to be re-operated. Only if a patient was evaluated at our out-patient clinic could reherniation have been scored; this occurred in 11 of 71 patients (16%). CONCLUSION: This technique is an effective and simple procedure to correct incisional hernias with acceptable complication rates and is feasible even in the more complicated hernias.

Health-related quality of life in patients treated for incisional hernia with an onlay technique.

BACKGROUND: An incisional hernia is a frequent complication of abdominal surgery. The repair of incisional hernias comes with a high risk of reherniation and serious complications. With the introduction of mesh repair, recurrence rates have decreased and subsequent clinical outcomes have improved. Whereas further research needs to be done to improve complication rates and recurrence, the focus has now been placed on quality-of-life outcomes in patients undergoing these repairs. The aim of this study was to investigate the long-term health-related quality of life (HRQL) of patients who were treated for incisional hernias using an onlay technique. PATIENTS AND METHODS: Over a period of 10 years (1997-2007), 101 patients with an incisional hernia were treated with an onlay marlex mesh, fixed on the fascia with skin staples. Of the 101 patients, there were 45 males and 56 females, and their mean age was 55 years. Nine patients died and 13 were lost during follow-up. Of the remaining 79 patients, eight refused to participate. The mean follow-up time was 64 months (normal distribution, standard deviation [SD] 35 months). The Short Form 36 (SF-36) and the Karnofsky Performance Status Scale (KPS) and a semi-structured interview were used to measure HRQL. RESULTS: Seventy-one of the 101 patients were evaluated at our out-patient clinic. Twenty-one patients (20%) had an open-abdomen treatment in their medical history. The median admission time was 4.5 days (quartiles 3-6.25). The mean follow-up time was 64 months (SD 35 months). A seroma was reported in 27 of the 101 patients (27%) and a wound infection in 22 patients (21%), of which five patients had to be re-operated. Only if a patient was evaluated at our out-patient clinic could reherniation be scored; this occurred in 11 of 71 patients (16%). The evaluation of HRQL showed equal SF-36 scores for patients treated for an incisional hernia compared to their matched controls. Patients with a history of an open-abdominal treatment did not score significantly lower compared to patients without such a treatment. The median KPS score was 75, indicating that activities could be performed with effort and patients had some signs of disease. CONCLUSION: HRQL is the same in patients treated for an incisional hernia compared to the matched controls. Therefore, the onlay technique seems to be an acceptable method to repair large incisional hernias.

Timely awareness and prevention of emerging chemical and biochemical risks in foods: proposal for a strategy based on experience with recent cases.

A number of recent food safety incidents have involved chemical substances, while various activities aim at the early identification of emerging chemical risks. This review considers recent cases of chemical and biochemical risks, as a basis for recommendations for awareness and prevention of similar risks at an early stage. These cases include examples of unapproved genetically modified food crops, intoxications with botanical products containing unintentionally admixed toxic herbs, residues of unapproved antibiotics and contaminants in farmed aquaculture species such as shrimp and salmon; and adverse effects of chemical and biological pesticides of natural origin. Besides case-specific recommendations for mitigation of future incidents of the same nature, general inferences and recommendations are made. It is recommended, for example, to establish databases for contaminants potentially present within products. Pro-active reconnaissance can facilitate the identification of products potentially contaminated with hazardous substances. In international trade, prevention and early identification of hazards are aided by management systems for product quality and safety, rigorous legislation, and inspections of consignments destined for export. Cooperation with the private sector and foreign authorities may be required to achieve these goals. While food and feed safety are viewed from the European perspective, the outcomes also apply to other regions.

Proficiency studies on the determination of paralytic shellfish poisoning toxins in shellfish.

Paralytic shellfish poisoning toxins are produced by dinoflagellates. Shellfish filtering these unicellular algae will accumulate the toxins and pose a health risk when consumed by man. In the European Union, paralytic shellfish poisoning toxins in bivalve molluscs are regulated at a maximum content of 80 microg/100 g (91/492/EEC). The current reference method in the European Union is the mouse bioassay, but alternative methods including the liquid chromatography methodology are preferred for ethical reasons. Analyses of suspected shellfish batches revealed, however, unacceptable differences in results reported by a small group of Dutch laboratories all using liquid chromatography methods with precolumn derivatization, followed by fluorescence detection. Therefore, a series of proficiency studies were undertaken among these laboratories. In the first three studies, participants were more or less allowed their own choice of method execution details. This approach yielded unsatisfactory results. A fourth study was then initiated in which a standardized method was mandatory. Two types of test material were used in the fourth study: lyophilized Cardium tuberculatum material containing saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX), and lyophilized mussel material containing dc-STX. The latter material was investigated in an interlaboratory study involving 15 participants and was considered as the reference material. Among the four laboratories, coefficients of variation (ANOVA) for C. tuberculatum material were 10% (n = 11) and 9% (n = 12) for STX and dc-STX, respectively, and for the reference material was 8% (n = 12) for dc-STX. The joint efforts showed that variability in analysis results between laboratories that all apply more or less the same method can be drastically improved if the methodology is rigorously standardized.