Realistic Worst-case Scenario Research Articles

Migration of Melamine and Its Derivatives from Melamine/Bamboo/Wheat Straw-Made Tableware Purchased from Internet Markets or Retail Shops in China.

The ecofriendly and sustainable concept of bamboo- and wheat straw-made tableware has gained attention in recent years. However, it is necessary to note that these kinds of tableware are composed of melamine (MEL)-formaldehyde resin with the addition of bamboo fibers or wheat straw. This study aims to explore the potential migration of MEL and its derivatives from the tableware and conduct a risk assessment. The study involved 46 bowls or cups purchased from Internet markets or retail shops in China, whose raw materials included MEL, bamboo, and wheat straw. There were four pieces of glass- or ceramic-made tableware used as the control group. Migration testing was performed according to the test conditions selected from the European Union Reference Laboratory for Food Contact Materials. Considering the realistic worst-case scenario, we measured the concentrations of MEL and its derivatives in food simulants using ultra-performance liquid chromatography-tandem mass spectrometry and estimated the exposure risks for adults and 1-year-old infants. MEL and its derivatives could migrate from MEL-, bamboo-, and wheat straw-made tableware with varying concentrations. The total migration was ranked as follows: bamboo-made tableware > MEL-made tableware > wheat straw-made tableware > glass- or ceramic-made tableware (p < 0.001). The primary contributor to the total concentration for MEL- and bamboo-made tableware was MEL, whereas cyanuric acid (CYA) was the main contributor for wheat straw-made tableware. Based on the total concentration of MEL and its derivatives and the strictest TDI value, the proportions of the calculated hazard quotient ≥1 for MEL-, bamboo-, and wheat straw-made tableware in adults were 53.50%, 92.30%, and 1.90%; and the proportions in 1-year-old infants increased to 86.00%, 100.00%, and 7.40%. The utilization of MEL-, bamboo-, and wheat straw-made tableware could be regarded as a significant source of human exposure to MEL and its derivatives. It is advisable for both adults and infants to refrain from using tableware manufactured with MEL and bamboo fiber, as it may increase the susceptibility to MEL-related diseases.

Small biochar particles hardly disintegrate under cryo-stress

Physical disintegration of biochar has been postulated to determine the persistence and mobility in soil of this recalcitrant carbon pool. Therein, freeze–thaw cycling can induce substantial physical stress to biochars. We here investigated the physical disintegration and subsequent mobilisation of five different biochars under “realistic worst-case scenarios” in a laboratory soil column setup as well as in shaking and sonication batch experiments. The mobilization of carbon from biochar particles (0.25–1 mm) was investigated in the absence of clay at a pH of 6.3 with and without 80 freeze–thaw cycles. The small biochar particles used in this study did not strongly disintegrate after freeze–thaw cycling, possibly because of freezing point depression in biochar micropores. Our results in comparison with findings in literature suggest that freeze–thaw-induced physical disintegration of biochar is a process more pronounced for large biochar particles containing substantial meso- and macropores. Biochars with larger ash fractions disintegrated more, presumably because of the ash-associated formation of unstable cavities within the biochar. Physical stability of biochars produced from the same feedstock at different pyrolysis temperatures decreased with increasing aromaticity, which may be linked to a higher rigidity of more aromatic structures. Moisture content in the soil increased carbon mobilization from biochar more than physical stress such as freeze–thaw cycling. The physical disintegration of biochar and subsequent mobilization of micro-and nanosized carbon should thus be considered of minor relevance and is often not a driving factor for biochar stability in soil.

Statistically based soil-climate exposure scenarios for aquatic pesticide fate modeling and exposure assessment in the Pampa Region of Argentina.

Although pesticides are used intensively in Argentina's Pampa region, the possibility of performing an environmental risk assessment (ERA) remains limited due to the absence of readily available databases to run pesticide fate models and the lack of standardized realistic worst-case scenarios. The aim of the present study was to further advance capacities for performing probabilistic ERAs in the Pampa region by dividing and parameterizing the region into functional soil-climate mapping units (SCU) and defining statistically based, worst-case soil-climate exposure scenarios. Results obtained demonstrate that the SCU selected for a specific modeling exercise should depend on the dissociation constant (Kd ) of the pesticide evaluated and whether short- or long-term pesticide fate modeling and risk assessment are needed. Four regionally representative SCUs were specifically identified for modeling the fate of pesticides with low, high, and intermediate values of Kd . Fate modeling of pesticides with an intermediate Kd requires the use of a different SCU for short- versus long-term pesticide modeling, whereas this distinction is not necessary for pesticides with both low and high Kd . The current definition of realistic, worst-case, soil-climate scenarios represents a crucial step toward better pesticide fate modeling and exposure assessment in Argentina's Pampa region. Integr Environ Assess Manag 2023;19:626-637. © 2022 SETAC.

Selection of scenarios for landscape-level risk assessment of chemicals: case studies for mammals

BackgroundFor landscape-level risk assessments of pesticides, the choice of the scenario is a key question, since it determines the outcome of a risk assessment. Typically, the aim is to select a realistic worst-case scenario. In the present study, landscapes from an area with a high proportion of cereal fields in France were analysed and simulations with population models for wood mouse, common vole, brown hare and European rabbit were conducted to understand if the worst-case character regarding pesticide exposure and population survival can be determined based on landscape features alone. Furthermore, it was analysed which landscape features relate with population survival and the magnitude of effects due to pesticide application. Answers to these question may help to decide whether landscape scenarios can be selected based on expert decision and whether the same scenarios may be used for different species or not.ResultsThere were species-specific landscape features relating to long-term population survival. A landscape that is worst-case for one species, was not necessarily worst-case for another. Furthermore, landscapes that were worst-case regarding population survival were often not worst-case regarding the magnitude of effects resulting from pesticide application. We also found that small landscapes were sometimes, but not always worst-case compared to larger landscapes. When small landscapes were worst-case, this was typical because of the artificial borders of the digitised landscape.ConclusionsLandscape analyses can help to obtain an approximate impression of the worst-case character of a landscape scenario. However, since it was difficult to consistently and reliably do this for single landscapes, it may be advisable to use a set of different landscapes for each risk assessment, which covers the natural variability. Depending on whether population survival shall be ensured or the magnitude of effects due to pesticides, different landscape structure and composition needs to be considered to establish a worst-case landscape scenario.

Migration of formaldehyde from ‘biobased’ bamboo/melamine cups: A Dutch retail survey

Bamboo/melamine cups had become popular, due to their ecofriendly and sustainable image. Some cups are marketed as biobased and biodegradable. These cups are made from melamine-formaldehyde resin to which bamboo fibers or powder are added. They may release formaldehyde and melamine into the beverage. In 2019 the Netherlands Food and Consumer Product Safety Authority conducted a market study. 46 cups were sampled in duplicate and tested for formaldehyde migration. 88% of the cups complied with the migration limit of 15 mg/kg. Some cups showed very high migration values, over 200 mg/kg. There is a high exposure of formaldehyde from other sources (food, environment). When applying a realistic worst-case scenario of a daily intake of 0.4 L of beverage from the cups, the health based guidance value is exceeded at a migration of 19 mg/kg and higher. For some of the cups that had a high migration of formaldehyde, health risks may occur. For food-utensils for babies and young children, the exposure is higher due to their lower body weight. The SML does not provide sufficient protection for babies and young children. Bamboo is not authorized in the EU as additive for plastic food contact materials. Therefore the Netherlands, Belgium, Luxembourg and other EU member states have actively banned these products from the market. Finally, bamboo/melamine tableware would suggest having a ‘green’ image and would contribute to the goals of the circular economy to use biobased raw materials, but by using it in combination with melamine-formaldehyde resin may affect food safety.

Endoscopies, blood‐borne viruses and blood donors: time to move on from precaution

Based on the Council of Europe directive which dictates regulatory requirements in Australia, blood donors are currently deferred from donating for 4months after an endoscopic procedure if either polyps were removed or a biopsy sample was taken. We aimed to assess the incidence of blood-borne viruses (BBVs) (HIV, hepatitis B and C) in blood donors who donated after an endoscopic procedure and evaluate the risk to blood safety through risk modelling. Donors from 1/1/2013 to 31/12/2017 with an endoscopy deferral on their blood donor file with pre- and post-BBV testing were analysed to determine an incidence of BBVs using standard methods. The standard blood donor cohort was used as a comparator group. Using the incidence of endoscopies and BBV risk, the total residual risk estimate of allowing donors to return postendoscopy without restriction was calculated. The incidence of a BBV postendoscopy in this large cohort of 16,283 where testing has been confirmed postendoscopy was zero (95% CI 0-0·000105). The upper confidence interval of the zero events is 10·5 per 100000 donations. Total positive donations from 2017 repeat donors were 1·87 per 100000 (95% CI 0·0000117-0·0000277). Sensitivity analysis demonstrated that the residual risk remained negligible under realistic worst-case scenarios. A BBV endoscopy deferral is not required for blood safety in Australia. The presented data has enabled us to submit a request for an exemption to our regulator, which has been approved and the policy change subsequently implemented by Lifeblood on 4/4/2020.

Ecotoxicity screening of novel phosphorus adsorbents used for lake restoration

Short-term standardized laboratory tests were carried out for evaluating acute and chronic toxicological effects of novel phosphorus (P) adsorbents on Raphidocelis subcapitata (algal growth rate inhibition) and on Daphnia magna (immobilization, with direct and indirect exposure to adsorbents, and uptake-depuration tests). Four P adsorbents were tested: two magnetic (HQ and Fe3O4) and two non magnetic (CFH-12® and Phoslock®). For the case of the algal growth inhibition test, the EC50 was 1.5 and 0.42 g L−1 for HQ and CFH-12®, respectively, and no inhibition patterns were observed neither for Fe3O4 nor for Phoslock®. When organisms were exposed to a direct contact, in the D. magna immobilization test, no statistically significant differences were found in the EC50 values among the four studied adsorbents. The huge difference between direct and indirect contact experiments suggests that toxicity is mainly physically mediated. The uptake-depuration test evidenced a much faster uptake and depuration rates for Phoslock®, which was precisely the adsorbent with the highest particle size. In a realistic worst-case scenario using data from Honda lake (Almería, Spain), where lake restoration is carried out by a adding a single large dose to bind surplus P in the lake, the predicted environmental concentrations for all adsorbents were lower than EC50 for all adsorbents and they were found to exceed a provisional limit value for ecotoxicity after a short-term exposure. All in all, since neither accumulation nor longer term effects of P adsorbents in the pelagic phase is expected, this risk may however, on a case-to-case basis, be acceptable.

Indoor Exposure to Toluene from Printed Matter Matters: Complementary Views from Life Cycle Assessment and Risk Assessment

A pronounced presence of toluene from rotogravure printed matter has been frequently observed indoors. However, its consequences to human health in the life cycle of magazines are poorly known. Therefore, we quantified human-health risks in indoor environments with Risk Assessment (RA) and impacts relative to the total impact of toxic releases occurring in the life cycle of a magazine with Life Cycle Assessment (LCA). We used a one-box indoor model to estimate toluene concentrations in printing facilities, newsstands, and residences in a best, average, and worst-case scenario. The modeled concentrations are in the range of the values measured in on-site campaigns. Toluene concentrations can be close or even surpass the occupational legal thresholds in printing facilities in realistic worst-case scenarios. The concentrations in homes can surpass the US EPA reference dose (69 μg/kg/day) in worst-case scenarios, but are still at least 1 order of magnitude lower than in press rooms or newsstands. However, toluene inhaled at home becomes the dominant contribution to the total potential human toxicity impacts of toluene from printed matter when assessed with LCA, using the USEtox method complemented with indoor characterization factors for toluene. The significant contribution (44%) of toluene exposure in production, retail, and use in households, to the total life cycle impact of a magazine in the category of human toxicity, demonstrates that the indoor compartment requires particular attention in LCA. While RA works with threshold levels, LCA assumes that every toxic emission causes an incremental change to the total impact. Here, the combination of the two paradigms provides valuable information on the life cycle stages of printed matter.

Tier-1 and Tier-2A Scenario Parameterisation and Example Calculations - In Support of the Revision of the Guidance Document on Persistence in Soil under Council Directive 91/414/EEC and Parliament and Council Regulation (EC) 1107/2009 (SANCO/9188/VI/97 re

European scenarios for exposure of soil organisms to Plant Protection Products are currently not available (EFSA Panel on Plant Protection Products and their Residues (PPR), 2010). In this document, the parameterisation of realistic worst-case scenarios for Tier-1 and Tier-2A simulations is described which are part of a tiered approach. The aim of this scheme is to assess such Predicted Environmental Concentrations (PEC), chosen to be the 90th spatial percentile, resulting from the use of the plant protection product. In order to account for the uncertainty in substance and soil properties, the Tier-2A scenarios are combinations of soil and climatic properties within a zone, for which the predicted concentration is equal to the 95th percentile of all concentrations within the area of annual crops. The selected soil profiles are based on digitised information from topsoil (organic matter and texture) combined with calculated average soil profiles available in the SPADE-1 database. The daily weather information for the scenarios is taken from the MARS database using the period 1990-2009. In order to have a sufficient overview on the differences between simulations performed with the analytical Tier-1 model and the numerical Tier-2A models, PEARL and PELMO test runs are performed covering all relevant substance properties and all evaluation depths. For each of the totalsoil scenarios, both models simulate nearly the same concentration. Small differences between PEARL and PELMO can be found for the pore-water scenarios due to differences in the calculation of soil moisture contents. The comparison with the analytical model shows that Tier-1 concentrations are usually above the respective Tier-2A concentrations in accordance with the philosophy of the tiered assessment scheme. However, due to the different handling of soil moisture, Tier-1 simulations may occasionally give concentrations below those of Tier 2A, which occurrence necessitates additional calibration using special model-adjustment factors

Do European Standard Disinfectant tests truly simulate in-use microbial and organic soiling conditions on food preparation surfaces?

The results from European standard disinfectant tests are used as one basis to approve the use of disinfectants in Europe. The design of these laboratory-based tests should thus simulate as closely as possible the practical conditions and challenges that the disinfectants would encounter in use. No evidence is available that the organic and microbial loading in these tests simulates actual levels in the food service sector. Total organic carbon (TOC) and total viable count (TVC) were determined on 17 visibly clean and 45 visibly dirty surfaces in two restaurants and the food preparation surfaces of a large retail store. These values were compared to reference values recovered from surfaces soiled with the organic and microbial loading, following the standard conditions of the European Surface Test for bactericidal efficacy, EN 13697. The TOC reference values for clean and dirty conditions were higher than the data from practice, but cannot be regarded as statistical outliers. This was considered as a conservative assessment; however, as additional nine TOC samples from visibly dirty surfaces were discarded from the analysis, as their loading made them impossible to process. Similarly, the recovery of test organisms from surfaces contaminated according to EN 13697 was higher than the TVC from visibly dirty surfaces in practice; though they could not be regarded as statistical outliers of the whole data field. No correlation was found between TVC and TOC in the sampled data, which re-emphasizes the potential presence of micro-organisms on visibly clean surfaces and thus the need for the same degree of disinfection as visibly dirty surfaces. The organic soil and the microbial burden used in EN disinfectant standards represent a realistic worst-case scenario for disinfectants used in the food service and food-processing areas.

Modelling groundwater contamination above the Asse 2 medium-level nuclear waste repository, Germany

The medium-level radioactive waste deposited in the Asse 2 salt mine, Germany, has a total activity of 1.2 × 1015 Bq (1 January 2002). The waste lies in a former mining chamber on the −511 m mining level close to the contact between the Mesozoic country rock and the Zechstein salt dome. The Mesozoic country rock is strongly faulted but the geometry of the fault pattern is incompletely known. Two tectonic cases are considered: a pessimistic case, which assumes that the radioactive source is linked to the surface by a single fault, and an optimistic case, which assumes that the radioactive source is not connected to any fault at all. The potential groundwater contamination by radioactive fluids expelled from the cavity is simulated with the TOUGH2 code for periods of up to 6,000 years, when the potential contamination reaches its greatest vertical extent. Two types of driving forces are considered: convergence of the rock salt surrounding the cavity and generation of H2 gas by the corrosion of iron, steel and other metallic components of the waste at low O2 fugacities. Rock-salt creep has the greatest potential impact, as it leads to a radioactive plume whose 1 Bq/L activity contour rises up to 240 m below the surface in the pessimistic tectonic case. The value of the model for the assessment of the environmental risk is limited. The knowledge of the hydrogeological situation is incomplete and the pessimistic tectonic case may not be pessimistic enough for a realistic worst-case scenario.

Dynamic assessment of the ecological risk of the discharge of produced water from oil and gas producing platforms

Since 1991 the North Sea countries (UK, Netherlands, Norway and Denmark) have put a lot of effort in the development of a decision support system for the legislation of the use and discharge of offshore exploration, drilling and production chemicals. The heart of this so-called `harmonised mandatory control system' is the `chemical hazard assessment and risk management' (CHARM) model. This model enables the ranking of chemicals on the basis of their intrinsic properties, using a realistic worst-case scenario. To meet the prerequisites of the model (simple and transparent calculation rules), the CHARM model uses a fixed dilution factor, assuming equal and constant dispersion of chemicals around the platform. In reality, however, the chemical follows a three-dimensional dispersion pattern which will change over time. To be able to use the principles of the CHARM model in such a dynamic situation for risk management, a new model has been developed by TNO in cooperation with Dutch Oil (NAM). This model gives a probabilistic estimation of the ecological risk of produced water, based upon a realistic calculation of the fate of components of produced water after discharge from the platform. Spatial and temporal variation in the concentration of chemicals is summarised in frequency distributions. The ecological risk is calculated for aquatic life, benthic life and the food chain. The model aims to support the selection of cost-effective mitigating measures for risk reduction.

Outcome of raising blood pressure in patients with penetrating trunk wounds

In many countries, the management of patients with traumatic wounds follows the guidelines from the American College of Surgeons Advanced Trauma Life Support Program for Physicians (ATLS) 1 American College of Surgeons. Shock. In: American College of Surgeons, ed. American College of Surgeons, Committee on Trauma. Advanced trauma life support program for physicians: instructor manual, 1997. Google Scholar but the protocol relating to penetrating wounds has recently come under scrutiny. Investigators have suggested that under ideal conditions delaying fluid resuscitation until operative intervention may improve survival. 2 Bickell WH Wall Jr, MJ Pepe PE et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries.. N Engl J Med. 1994; 331: 1105-1109 Crossref PubMed Scopus (1692) Google Scholar Raising the blood pressure in these patients may lead to increased haemorrhage caused by dislodgement of thrombus. 3 Shafton GW Clive CJ Dennis C Harris B Fundamentals of physiologic control of arterial hemorrhage.. Surgery. 1965; 58: 851-856 PubMed Google Scholar Intravenous fluids may also dilute coagulation factors 4 Bickell WH Bruttig SP Millnamow GA OBenar J Wake CE The detrimental effects of intravenous crystalloid after aortotomy in swine.. Surgery. 1991; 110: 529-536 PubMed Google Scholar and lower blood viscosity, decreasing resistance to flow around an incomplete thrombus. 5 Bickell WH Bruttig SP Millnamow GA OBenar J Wake CE Use of hypertonic saline/dextran versus lactated Ringer's solution as a resuscitation fluid after uncontrolled aortic hemorrhage in anesthetized swine.. Ann Emerg Med. 1992; 21: 1077-1085 Summary Full Text PDF PubMed Scopus (149) Google Scholar We tested the hypothesis that raising blood pressure between admission and operation in patients with penetrating wounds to the trunk had a deleterious effect on outcome, under a more realistic worst-case scenario.

An investigation of the desensitizing effects by high power HF broadcast transmitters on HF airborne receivers

The actual increase in power and number of high-frequency (HF) broadcasting transmitters (Tx) may strongly interfere with collocated (and even remote) radio receivers (Rx) over broad frequency ranges. The most vulnerable to harmful desensitization interference effects are airborne HF Rx flying in the proximity to the HF broadcasting Tx. In these cases extensive analysis and computational developments are essential to assess the feasibility of reliable operation of HF radio communication links. A general semi-empirical computational method is developed for quantifying the dominant mutual interference desensitization effects on a victim Rx followed by the investigation of a specific modern HF Rx used for communication with aircraft. Realistic worst-case scenarios of the airborne HF victim Rx are developed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>