Risk Assessment and Safety Evaluation Using Probabilistic Fault Tree Analysis

Risk assessment is an essential prelude to the development of accident prevention strategies in any chemical or petrochemical industry. Many techniques and methodologies such as HAZOP, failure mode effect analysis, fault tree analysis, preliminary hazard analysis, quantitative risk assessment and probabilistic safety analysis are available to conduct qualitative, quantitative, and probabilistic risk assessment. However, these methodologies are limited by: extensive data requirements, the length of study, results are not directly interpretable for decision making, simulation is often difficult, and they are applicable only at the operation or late design stage. Khan et al. (2001a) recently proposed a detailed methodology for risk assessment and safety evaluation. This methodology is simple, yet it is effective in safety and design-related decision making, and it has been applied successfully to many case studies. It is named SCAP, where S stands for safety, C and A stand for credible accident respectively, and P stands for probabilistic fault tree analysis. This paper recapitulates the SCAP methodology and demonstrates its application to a petrochemical plant.     

From Assessment to Policy: Lessons Learned from the U.S. National Assessment

The process of translating scientific information into timely and useful insights that inform policy and resource management decisions, despite the existence of uncertainties, is a difficult and challenging task. Policy-focused assessment is one approach to achieving this end. It is an ongoing process that engages both researchers and end-users to analyze, evaluate and interpret information from multiple disciplines to draw conclusions that are timely and useful for decision makers. This paper discusses key characteristics of a policy-focused assessment process, including (1) ongoing collaboration between the research, assessment, and stakeholder communities; (2) a focus on stakeholder information needs; (3) multidisciplinary approaches; (4) use of scenarios to deal with uncertainties; and (5) evaluation of risk management options. We illustrate the particular challenge to assessors of providing the specific types of insights stakeholders need to effectively influence policy decisions. And we discuss the role that assessment can play in formulating an agenda for future research. Examples from the U.S. National Assessment of “The Potential Consequences of Climate Variability and Change for the United States” are used to illustrate a policy-focused assessment process. For many of the participants, the first U.S. National Assessment was an extraordinary learning experience about how to develop better ways of conducting assessments.     

基于故障树方法的非计划再次手术风险评估

目的 探索一种适合于在过程复杂、环境多变、风险多样的手术治疗系统中,对术前准备、术中操作、术后医疗护理及管理等贯穿围手术期全过程进行风险评估的方法。方法 通过危险事件的风险影响因子识别、定性分析与定量分析、基本事件综合风险等级评价,绘制具有实践操作意义的风险矩阵图,全面识别手术治疗系统风险、科学分析危险事件与风险影响因子,有效评价风险等级与可容忍度。结果 构建包括7个中间事件、29个基本事件、9个逻辑或门和1个逻辑与门的非计划再次手术故障树模型,故障树由8个一阶割集和104个二阶割集组成。当所有最小割集均存在时,被调查医院非计划再次手术的发生概率为0.950 10,同时确定25个基本事件在该医院的综合风险重要性等级,并根据绘制的风险图谱进一步确定风险应对的优先顺序。结论 基于故障树的手术治疗系统风险评估方法,可以全面识别手术治疗系统风险,科学分析风险影响因子,有效评价风险等级。     

Estimation of Multimedia Inorganic Arsenic Intake in the U.S. Population

Arsenic is widely distributed in the environment by natural and human means. The potential for adverse health effects from inorganic arsenic depends on the level and route of exposure. To estimate potential health risks of inorganic arsenic, the apportionment of exposure among sources of inorganic arsenic is critical. In this study, daily inorganic arsenic intake of U.S. adults from food, water, and soil ingestion and from airborne particle inhalation was estimated. To account for variations in exposure across the U.S., a Monte Carlo approach was taken using simulations for 100,000 individuals representing the age, gender, and county of residence of the U.S. population based on census data. Our analysis found that food is the greatest source of inorganic arsenic intake and that drinking water is the next highest contributor. Inhalation of airborne arsenic-containing particles and ingestion of arsenic-containing soils were negligible contributors. The exposure is best represented by the ranges of inorganic arsenic intake (at the 10^th and 90^th percentiles), which were 1.8 to 11.4 µg/day for males and 1.3 to 9.4 µg/day for females. Regional differences in inorganic arsenic exposure were due mostly to consumption of drinking water containing differing inorganic arsenic content rather than to food preferences.     

美国州立公园体系的发展、特征与评估

美国州立公园与国家公园相比,更强调满足州内居民就近户外休闲游憩需求的功能,这使得其在美国整体公共户外休闲空间体系中占据特殊的位置。在中国第一次全面地研究了美国州立公园体系的发展、特征及与国家公园体系的关系,特别是以部分州为例研究了美国州立公园的分类、质量评估、可达性与空间分布评估等关键问题。研究认为,州立公园的意义在于既缓解了美国国家公园面临的巨大旅游游憩压力,也满足了大众户外休闲游憩的需求。这值得中国在目前构建国家公园与自然保护地体系的同时予以借鉴。最后基于中国的实际需求与挑战,探讨了在省域/区域层次加强构建地方公园、保护地和游憩地体系建设的必要性与途径。     

Colonial to modern skeletal change in the U.S.A.

Eighty-two people dating from 1675 to 1879 compared with 182 modern middle-class White and Black skeletons test the myths of radical changes produced by improved diet, less disease, and nineteenth century immigration. Longevity increases and health and growth improvement is clearest in reduced juvenile deaths (census data) and deepening of true pelvis. Stature increase is minimal (though seventeenth century Londoners and modern West Africans are shorter than Colonial to Modern Americans); teeth deteriorate and for cultural reasons fractures increase. Clavicles and forearms elongate. From Old to New World Colonial samples there is a noticeable skull change (and a greater Old World to Modern contrast) but White Colonial to Modern shows strong continuity surprisingly, the key changes being increasing head height, and retraction of face with increasing nose projection, and longer mastoids, resulting from selection and mixture. Blacks change more, possibly from Indian and White mixture. Variabilities are above average. Change is much less than expected, and apparently involves heterosis and selection as well as the obvious health advance and mixtures.     

Distribution of benthic diatoms in U.S. rivers in relation to conductivity and ionic composition

• 1 We quantified the relationships between diatom relative abundance and water conductivity and ionic composition, using a dataset of 3239 benthic diatom samples collected from 1109 river sites throughout the U.S.A. [U.S. Geological Survey National Water‐Quality Assessment (NAWQA) Program dataset]. This dataset provided a unique opportunity to explore the autecology of freshwater diatoms over a broad range of environmental conditions.
• 2 Conductivity ranged from 10 to 14 500 μS cm^?1, but most of the rivers had moderate conductivity (interquartile range 180–618 μS cm^?1). Calcium and bicarbonate were the dominant ions. Ionic composition, however, varied greatly because of the influence of natural and anthropogenic factors.
• 3 Canonical correspondence analysis (CCA) and Monte Carlo permutation tests showed that conductivity and abundances of major ions (HCO + CO, Cl^?, SO, Ca²⁺, Mg²⁺, Na⁺, K⁺) all explained a statistically significant amount of the variation in assemblage composition of benthic diatoms. Concentrations of HCO + CO and Ca²⁺ were the most significant sources of environmental variance.
• 4 The CCA showed that the gradient of ionic composition explaining most variation in diatom assemblage structure ranged from waters dominated by Ca²⁺ and HCO + CO to waters with higher proportions of Na⁺, K⁺, and Cl^?. The CCA also revealed that the distributions of some diatoms correlated strongly with proportions of individual cations and anions, and with the ratio of monovalent to divalent cations.
• 5 We present species indicator values (optima) for conductivity, major ions and proportions of those ions. We also identify diatom taxa characteristic of specific major‐ion chemistries. These species optima may be useful in future interpretations of diatom ecology and as indicator values in water‐quality assessment.

     

Genomics: Applications,Challenges, and Opportunities for the U.S. Environmental Protection Agency

Genomics information has great potential to enhance assessment of risks to human health and the environment. Although understanding genomic responses with respect to adverse ecological and human health outcomes is not, as yet, established, it is important to consider the likely future impacts of genomics technologies on risk assessment and decision-making. Four areas are identified as those likely to be influenced by the generation of genomics information within, and the submission of such information to, the U.S. Environmental Protection Agency (USEPA): risk assessment, prioritization of contaminants and contaminated sites, monitoring, and reporting provisions. For each of these risk assessment and regulatory applications, representative activities are presented to illustrate the application. Three major challenges for the USEPA associated with genomics are also identified in the areas of research, technical development, and capacity. The USEPA's initial activities to address these challenges are discussed. The Agency recognizes it must be prepared to use genomics information, and that many scientific, policy, ethical, and legal concerns will need to be addressed. The USEPA also recognizes it is essential to continue to collaborate with other federal agencies, academia, the regulated community, and other stakeholders in order to benefit from ongoing advances in genomics in the wider scientific and regulatory communities.     

基于论文和专利的中美脑科学领域对比研究

脑科学是生命科学领域的研究前沿和热点,美国是该领域的科技强国。本文基于科技论文和专利数据,利用文献计量学的定量分析方法,比较中国和美国在脑科学领域的理论研究和应用研究的差距。结果表明,基于论文分析的理论研究对比,发现中国较美国起步晚,目前论文数量上的差距正在缩小,但学术影响力的差距较大;基于专利分析的应用研究对比,发现中国在专利申请数量上已略超过美国,但在代表专利技术价值和市场价值的国际专利数量、技术布局、龙头企业及企业参与研发比重等方面,差距还非常之大。     

Problems of epidemiology and prophylaxis of alveococcosis (multilocular echinococcosis): a general review--with particular reference to the U.S.S.R

Lukashenko N. P., 1971. Problems of epidemiology and prophylaxis of alveococcosis (multilocular echinococcosis): a general review—with particular reference to the U.S.S.R. International Journal for Parasitology, 1: 125–134. Alveococcus multilocularis is an extremely dangerous, often fatal, parasite of man. The main endemic areas are southern G.F.R., Austria, Switzerland, northern U.S.A., Canada and Japan. The circulation of Alveococcus depends on complex biocenotic relationships between certain carnivores and numerous microtine rodents. Their roles vary widely according to terrain, reproduction, season, epizootics, animals of prey and interspecific rivalry. The infection rate of definitive hosts each year depends on the prevailing numbers of intermediate hosts in the corresponding biotope, and vice versa. The significance of the fox, polar fox, dog fox, wolf and spotted cat as definitive hosts is considered. Twenty-nine species of rodents have been recorded as intermediate hosts but the roles of insectivores appear insignificant, while those of birds and wild ungulates have yet to be studied. Domestic ungulates probably do not take part in the life-cycle of A. multilocularis. Domestic cats and dogs may be involved accidentally. The role of synanthropic rodents has not yet been fully elucidated but house mice show a high degree of infectivity. Human infection is influenced by ecological factors, living conditions, occupation and level of hygiene practised: dangerous sources of infection are team dogs, unboiled drinking water from melted ice, the skins of fur animals and possibly insects. Secondary sources are other contaminated waters, dust, wild berries and possibly vegetables. Data on the incidence of alveococcosis according to sex is contradictory; the differences between the infection rates of men and women in different regions almost certainly depend on their several modes of life and occupations. The majority of diseased persons are between 19 and 40 years old; infection probably takes place during childhood and is fatal before old age. Prophylactic measures differ markedly from those for (unilocular) echinococcosis, and must be directed towards eliminating the possibility of infecting definitive hosts and towards increased hygiene education.     

Hosts of Lutzomyia shannoni (Diptera: Psychodidae) in relation to vesicular stomatitis virus on Ossabaw Island, Georgia, U.S.A.

Abstract. Hosts of Lutzomyia shannoni Dyar, a suspected biological vector of the New Jersey serotype of vesicular stomatitis (VSNJ) virus, were determined using an indirect enzyme-linked immunosorbent assay (ELISA) of 333 blood-fed female sandflies collected from their diurnal resting shelters on Ossabaw Island, Georgia, U.S.A. Sandflies had fed primarily on white-tailed deer ( Odocoileus virginianus ) (81%) and to a lesser extent on feral swine ( Sus scrofa ) (16%), two species of host infected annually with VSNJ. Other hosts were raccoons ( Procyon lotor ) and horses ( Equus caballus ) or donkeys ( E. asinus ), with only two (<1%) mixed bloodmeals from deer/raccoon and deer/swine. A larger proportion of feedings on feral swine was detected in maritime live oak forests than in mixed hardwood forests. These findings are consistent with the hypothesis that L. shannoni is a primary vector of VSNJ virus on Ossabaw Island.     

Closing the Loop on Cadmium - An Assessment of the Material Cycle of Cadmium in the U.S. (11 pp)

Goal, Scope and Background In this study, the major flows of cadmium in the U.S. economy are quantified and the primary sinks are identified to gauge the need for additional policy to minimize the potential human health and ecosystem risks associated with these flows. Because of the concurrent occurrence of cadmium and zinc in ore, we also consider the relevant portions of the material cycle of zinc. Methods We estimated the flows of cadmium through U.S. manufacturing using a mass balance approach with data provided by the U.S. Geological Survey's Minerals Yearbook. Cadmium emissions factors were created using facility specific information found in the U.S. Toxics Release Inventory and were used to model future losses. Data gaps were filled through review of relevant literature. We modeled the import and sales of nickel-cadmium batteries with rechargeable battery usage trends and estimates of market share by battery chemistry. Results and Conclusion Primary cadmium in the U.S. is almost exclusively produced as a co-product of zinc. Almost all zinc and cadmium mined in the U.S. is exported to foreign smelters as ore concentrate. We estimate that the bulk of cadmium consumed in the U.S. economy (~90%) is imported in the form of nickel-cadmium rechargeable batteries. These batteries can be divided into the larger wet-cells and portable rechargeable batteries (PRB). The collection rate for the recycling of large wet cells was found to be high (80%) while the collection rate for PRBs is low (5-20%). The Rechargeable Battery Recycling Corporation (RBRC) is responsible for the collection of these batteries which are recycled exclusively by the International Materials Reclamation Company (INMETCO). The remaining PRBs are generally disposed of in municipal solid waste (MSW) landfills. This study provides a detailed substance flow analysis of U.S. stocks and flows of cadmium in products, however additional research is needed to better quantify the associated exposures and risks. Recommendation and Perspective Based on our analysis, we make four recommendations. First we suggest that if cadmium is to be used, it should be used in long-lived products that can be easily collected and recycled with minimal losses. Second, continued cadmium use should be coupled with renewed efforts on the part of policy-makers to encourage the collection and recycling of cadmium-bearing products. At present, consumers do not see the environmental cost associated with the proper disposal of the cadmium content of NiCd batteries. Policy options for improving recycling rates include collecting deposits and providing rewards for the return of spent batteries, taxing or otherwise discouraging discarding PRBs in municipal solid waste, and providing incentives for extended producer responsibility. Third, we highlight the importance of the connection between zinc mining and the supply of cadmium in designing an effective policy to manage the risks associated with cadmium. Fourth, we recommend that policy measures be taken to provide the necessary data required to improve our understanding of the flow of cadmium into the U.S. in the form of product imports and the amount of cadmium lost or disposed of by recycling processes.     

Human Exposure to Malathion during a Possible Vector-Control Intervention against West Nile Virus. II: Evaluation of the Toxicological Risks Using a Probabilistic Approach

In order to prevent the propagation of West Nile Virus (WNV), insecticide sprayings have been carried out in several locations in North America since 1999 with the objective of controlling the mosquito populations that transmit this pathogen. An attempt to quantitatively compare the risk of developing a health response to WNV infection with the toxicological risk of insecticides is presented here. First, the acute and subchronic environmental concentrations resulting from repeated spraying events were modeled according to a reasonable worst-case spraying sequence established in an intervention program proposed by the Government of Quebec (Canada). Second, probability density functions (PDF) were established for some exposure parameters according to the data for the concerned population, when feasible. Monte Carlo analyses were performed by incorporating these PDF into the equations used to calculate the daily absorbed doses resulting from the exposure scenarios presented in the companion article (this issue). The results showed that for a significant proportion of the population, aerial and, to a lesser extent, ground sprayings of malathion can generate acute and subchronic exposure that may exceed some levels of toxicological concern based on the USEPA's reference values. Indeed, in the case of acute exposure following aerial spraying for infants, toddlers, and children, these proportions were respectively 37.1%, 59.5%, and 32.8% of the individuals, and 27.3%, 41.3%, and 24.9% following subchronic exposure. For ground spraying, these values were 12.5%, 24.2%, 8.8%; and 9.8%, 16.5%, and 7.4%. These results allowed the comparison of the probability of exceeding a level of toxicological concern for malathion exposure with the probability of developing WNV symptoms. This comparison shows that in some circumstances, the toxicological risk of malathion may exceed the infectious risk of WNV.     

Plan for an Integrated Human and Environmental Risk Assessment in the S. Domingos Mine Area (Portugal)

The need for the integration of the assessment of human and ecological risks in contaminated areas, such as derelict mines, widely increases. The risk assessment process is becoming a powerful tool to provide sound scientific bases for decision-making processes. In Portugal, the risk assessment process is in its early years and the lack of multidisciplinary teams of experts is frequently mentioned as the main obstacle to its implementation. Therefore, the majority of the reclamation actions are based on impact assessment studies that usually are characterized by few biological and toxicological considerations. In order to account for some of these constraints, the ecological risk assessment framework proposed by the U.S. Environmental Protection Agency was used to plan the assessment of human and ecological risks posed by the high concentrations of metals scattered in the vicinity of S. Domingos mine, a cuprous pyrite mine located in the Southeast Alentejo (Portugal). This study presents the problem formulation phase of the assessment. It includes all the scientific information available for the area, a conceptual model, and an analysis plan for the risk assessment process. Following a tiered approach, several tasks were planned in order to acquire chemical, toxicological, and ecological information, in order to compensate for the lack of toxicity data for site-specific species.     

Cadaveric Tissue Supply to the Commercial Sector For Research: Collaboration between NHS Pathology and NBS Tissue Services in the U.K., Extending the Options for Donors

The Peterborough Hospital Human Tissue Bank (PHHTB) and National Blood Service Tissue Services (London and South East Zone) (NBSTS) operate within the U.K. National Health Service (NHS) and have a system in place to retrieve cadaveric tissues for commercial sector research. The collaboration meets the aims of PHHTB and NBSTS and is legal, ethical and safe. This paper presents the results of the first 20 successful retrievals referred from NBSTS to PHHTB. Cadaveric retrieval of tissue for research extends the options for donors and their relatives. The research option is particularly welcomed in cases where clinical retrieval for tissue transplantation is contraindicated. We believe the system is applicable to other centres.     

割手密2C型蛋白磷酸酶ScPP2C基因的克隆与表达分析

割手密由于具有抗病、抗虫、抗逆等潜在的有利基因,历来被用于甘蔗的抗性遗传改良。在割手密中克隆编码2C型蛋白磷酸酶(protein phosphatase 2C, PP2C)的基因,并分析其在干旱胁迫下的差异表达。本研究利用RT-PCR方法从割手密叶片中克隆得到PP2C基因的CDS全长序列,利用生物信息学在线软件对PP2C蛋白的理化性质、蛋白结构进行预测分析,并采用实时荧光定量的方法分析该基因在不同干旱处理下的差异表达。结果显示从割手密中克隆到一个全长951 bp编码316个氨基酸的2C型蛋白磷酸酶基因,命名为ScPP2C,GenBank登录号为MG322120。荧光定量分析表明,随着干旱胁迫时间的延长,其表达量呈先上调后下调的表达模式,说明该基因是干旱胁迫诱导型基因。本研究通过挖掘甘蔗野生种割手密中的抗旱新基因ScPP2C,为甘蔗野生种质资源开发利用、转基因抗旱甘蔗新品种的选育提供了参考依据。