--二氧化氯专项风险评价评价
二氧化氯气体风险评估报告
CHLORINE DIOXIDE (GAS)This report contains the collective views of an international group of experts and does not necessarily represent the decisions or the stated policy of the United Nations Environment Programme, the International Labour Organization, or the World Health Organization.Concise International Chemical Assessment Document 37First draft prepared by Dr Stuart Dobson, Institute of Terrestrial Ecology, Huntingdon, United Kingdom, and Mr Richard Cary, Health and Safety Executive, Liverpool, United KingdomPublished under the joint sponsorship of the United Nations Environment Programme, the International Labour Organization, and the World Health Organization, and produced within the framework of the Inter-Organization Programme for the Sound Management of Chemicals.World Health OrganizationGeneva, 2002The International Programme on Chemical Safety (IPCS), established in 1980, is a joint venture of the United Nations Environment Programme (UNEP), the International Labour Organization (ILO), and the World Health Organization (WHO). The overall objectives of the IPCS are to establish the scientific basis for assessment of the risk to human health and the environment from exposure to chemicals, through international peer review processes, as a prerequisite for the promotion of chemical safety, and to provide technical assistance in strengthening national capacities for the sound management of chemicals.The Inter-Organization Programme for the Sound Management of Chemicals (IOMC) was established in 1995 by UNEP, ILO, the Food and Agriculture Organization of the United Nations, WHO, the United Nations Industrial Development Organization, the United Nations Institute for Training and Research, and the Organisation for Economic Co-operation and Development (Participating Organizations), following recommendations made by the 1992 UN Conference on Environment and Development to strengthen cooperation and increase coordination in the field of chemical safety. The purpose of the IOMC is to promote coordination of the policies and activities pursued by the Participating Organizations, jointly or separately, to achieve the sound management of chemicals in relation to human health and the environment.WHO Library Cataloguing-in-Publication DataChlorine dioxide (gas).(Concise international chemical assessment document ; 37)1.Chlorine compounds - toxicity2.Oxides - toxicity3.Risk assessment4.Occupational exposure I.International Programme on Chemical SafetyII.SeriesISBN 92 4 153037 5 (NLM Classification: QD 181.C5)ISSN 1020-6167The World Health Organization welcomes requests for permission to reproduce or translate its publications, in part or in full. Applications and enquiries should be addressed to the Office of Publications, World Health Organization, Geneva, Switzerland, which will be glad to provide the latest information on any changes made to the text, plans for new editions, and reprints and translations already available.©World Health Organization 2002Publications of the World Health Organization enjoy copyright protection in accordance with the provisions of Protocol 2 of the Universal Copyright Convention. All rights reserved.The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city, or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Germany, provided financial support for the printing of this publication.Printed by Wissenschaftliche Verlagsgesellschaft mbH, D-70009 Stuttgart 10TABLE OF CONTENTSFOREWORD1. EXECUTIVE SUMMARY2. IDENTITY AND PHYSICAL/CHEMICAL PROPERTIES3. ANAL YTICAL METHODS3.1 Workplace air monitoring3.2 Biological monitoring in humans4. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE5. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION6. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE6.1 Environmental levels6.2 Occupational exposure7. COMPARATIVE KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS8. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS8.1 Single exposure8.2 Irritation and sensitization8.3 Short-term exposure8.3.1 Inhalation8.3.2 Oral8.4 Medium-term exposure8.5 Long-term exposure and carcinogenicity8.6 Genotoxicity and related end-points8.6.1 Studies in bacteria8.6.2 In vitro studies in mammalian systems8.6.3 In vivo studies in mammalian systems8.6.4 Studies in germ cells8.6.5 Other studies8.7 Reproductive toxicity8.7.1 Effects on fertility8.7.2 Developmental toxicity8.8 Immunological and neurological effects9. EFFECTS ON HUMANS9.1 Drinking-water studies10. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND FIELD11. EFFECTS EV ALUATION11.1 Evaluation of health effects11.1.1 Hazard identification and dose–response assessment11.1.2 Criteria for setting tolerable intakes/concentrations or guidance values for chlorine dioxide gas11.1.3 Sample risk characterization11.2 Evaluation of environmental effects12. PREVIOUS EV ALUA TIONS BY INTERNATIONAL BODIESREFERENCESAPPENDIX 1 — SOURCE DOCUMENTAPPENDIX 2 — CICAD PEER REVIEWAPPENDIX 3 — CICAD FINAL REVIEW BOARDINTERNATIONAL CHEMICAL SAFETY CARDRÉSUMÉ D’ORIENTATIONRESUMEN DE ORIENTACIÓNFOREWORDConcise International Chemical Assessment Documents (CICADs) are the latest in a family of publications from the International Programme on Chemical Safety (IPCS) —a cooperative programme of the World Health Organization (WHO), the International Labour Organization (ILO), and the United Nations Environment Programme (UNEP). CICADs join the Environmental Health Criteria documents (EHCs) as authoritative documents on the risk assessment of chemicals.International Chemical Safety Cards on the relevant chemical(s) are attached at the end of the CICAD, to provide the reader with concise information on the protection of human health and on emergency action. They are produced in a separate peer-reviewed procedure at IPCS. They may be complemented by information from IPCS Poison Information Monographs (PIM), similarly produced separately from the CICAD process.CICADs are concise documents that provide summaries of the relevant scientific information concerning the potential effects of chemicals upon human health and/or the environment. They are based on selected national or regional evaluation documents or on existing EHCs. Before acceptance for publication as CICADs by IPCS, these documents undergo extensive peer review by internationally selected experts to ensure their completeness, accuracy in the way in which the original data are represented, and the validity of the conclusions drawn.The primary objective of CICADs is characterization of hazard and dose–response from exposure to a chemical. CICADs are not a summary of all available data on a particular chemical; rather, they include only that information considered critical for characterization of the risk posed by the chemical. The critical studies are, however, presented in sufficient detail to support the conclusions drawn. For additional information, the reader should consult the identified source documents upon which the CICAD has been based.Risks to human health and the environment will vary considerably depending upon the type and extent of exposure. Responsible authorities are strongly encouraged to characterize risk on the basis of locally measured or predicted exposure scenarios. To assist the reader, examples of exposure estimation and risk characterization are provided in CICADs, whenever possible. These examples cannot be considered as representing all possible exposure situations, but are provided as guidance only. The reader is referred to EHC 1701 for advice on the derivation of health-based guidance values.While every effort is made to ensure that CICADs represent the current status of knowledge, new information is being developed constantly. Unless otherwise stated, CICADs are based on a search of the scientific literature to the date shown in the executive summary. In the event that a reader becomes aware of new information that would change the conclusions drawn in a CICAD, thereader is requested to contact IPCS to inform it of the new information.ProceduresThe flow chart shows the procedures followed to produce a CICAD. These procedures are designed to take advantage of the expertise that exists around the world —expertise that is required to produce the high-quality evaluations of toxicological, exposure, and other data that are necessary for assessing risks to human health and/or the environment. The IPCS Risk Assessment Steering Group advises the Co-ordinator, IPCS, on the selection of chemicals for an IPCS risk assessment, the appropriate form of the document (i.e., EHC or CICAD), and which institution bears the responsibility of the document production, as well as on the type and extent of the international peer review.The first draft is based on an existing national, regional, or international review. Authors of the first draft are usually, but not necessarily, from the institution that developed the original review. A standard outline has been developed to encourage consistency in form. The first draft undergoes primary review by IPCS and one or more experienced authors of criteria documents to ensure that it meets the specified criteria for CICADs.The draft is then sent to an international peer review by scientists known for their particular expertise and by scientists selected from an international roster compiled by IPCS through recommendations from IPCS national Contact Points and from IPCS Participating Institutions. Adequate time is allowed for the selected experts to undertake a thorough review. Authors are required to take reviewers’ comments into account and revise their draft,if necessary. The resulting second draft is submitted to a Final Review Board together with the reviewers’ comments.A consultative group may be necessary to advise on specific issues in the risk assessment document.The CICAD Final Review Board has several important functions:to ensure that each CICAD has been subjected to an appropriate and thorough peer review;to verify that the peer reviewers’ comments have been addressed appropriately;to provide guidance to those responsible for the preparation of CICADs on how to resolve any remaining issues if, in the opinion of the Board, the author has not adequately addressed all comments of the reviewers; andto approve CICADs as international assessments.Board members serve in their personal capacity, not as representatives of any organization, government, or industry. They are selected because of their expertise in human and environmental toxicology or because of their experience in the regulation of chemicals. Boards are chosen according to the range of expertise required for a meeting and the need for balanced geographicrepresentation.Board members, authors, reviewers, consultants, and advisers who participate in the preparation of a CICAD are required to declare any real or potential conflict of interest in relation to the subjects under discussion at any stage of the process. Representatives of nongovernmental organizations may be invited to observe the proceedings of the Final Review Board. Observers may participate in Board discussions only at the invitation of the Chairperson, and they may not participate in the final decision-making process.1. EXECUTIVE SUMMARYThis CICAD on chlorine dioxide gas was based on a review of human health concerns (primarily occupational) prepared by the United Kingdom’s Health and Safety Executive (Health and Safety Executive, 2000). This document focuses on exposures via routes relevant to occupational settings, principally related to the production of chlorine dioxide, but also contains environmental information. The health effects and environmental fate and effects of chlorine dioxide used in the treatment of drinking-water, together with those of halogenated organics produced by the interaction between the disinfectant and other materials present in the water, are covered in a recent Environmental Health Criteria document (IPCS, 2000) and are not dealt with in detail here. Data identified as of September 1998 were covered in the Health and Safety Executive review. A further literature search was performed up to January 1999 to identify any additional information published since this review was completed. Since no source document was available for environmental fate and effects, the primary literature was searched for relevant information. Information on the nature of the peer review and availability of the source document is presented in Appendix 1. Information on the peer review of this CICAD is presented in Appendix 2. This CICAD was approved as an international assessment at a meeting of the Final Review Board, held in Stockholm, Sweden, on 25–28 May 1999. Participants at the Final Review Board meeting are presented in Appendix 3. The International Chemical Safety Card for chlorine dioxide (ICSC 0127), prepared by the International Programme on Chemical Safety (IPCS, 1993), has also been reproduced in this document.Chlorine dioxide (ClO2, CAS No. 10049-04-4) exists as a greenish yellow to orange gas at room temperature. Chlorine dioxide gas is explosive when its concentration in air exceeds 10% v/v. It is water soluble, and solutions are quite stable if kept cool and in the dark. It is marketed and transported as a stabilized aqueous solution, generally less than 1% w/v (more concentrated forms are explosive).Occupational exposure to chlorine dioxide gas may occur during its manufacture, in the paper and pulp bleaching industries, during charging of the aqueous solution into drums, and during its use as a sterilizing agent in hospitals, as a biocide in water treatment, and as an improving agent in flour. During manufacture and subsequent captive use of the gas, good process plant control is essential because of the explosive nature of the gas. Furthermore, once the gas is absorbed in water, it has a low volatility. For these reasons, inhalation exposure is anticipated to be minimal.Limited occupational exposure data are available in relation to the manufacture and uses of chlorine dioxide; the measured or estimated concentrations indicated that all personal airborne exposures (in the United Kingdom) were below 0.1 ppm (0.28 mg/m3) 8-h time-weighted average (TWA) and 0.3 ppm (0.84 mg/m3) 15-min reference period.The most common dermal exposure may arise from contact with aqueous solutions of up to 1% of the substance during preparation and use. It is predicted that dermal exposure from contact with the aqueous solution in occupational settings will range from 0.1 to 5 mg/cm2 per day.Toxicokinetic data are limited, although it would seem unlikely that there would be any significant systemic absorption and distribution of intact chlorine dioxide by dermal or inhalation routes. It is possible that other derivatives, such as chlorate, chlorite, and chloride ions, could be absorbed and widely distributed. One study shows that "chlorine" (chemical form not characterized) derived from aqueous chlorine dioxide is absorbed by the oral route, with a wide distribution and rapid and extensive elimination. No clear information is available on the identity of metabolites, although breakdown products are likely to include, at least initially, chlorites, chlorates, and chloride ions.Given the reactive nature of chlorine dioxide, it seems likely that health effects would be restricted to local responses. There are no quantitative human data, but chlorine dioxide is very toxic by single inhalation exposure in rats. There were no mortalities following exposure to 16 ppm (45 mg/m3) for 4 h, although pulmonary oedema and emphysema were seen in all animals exposed to 16–46 ppm (45–129 mg/m3) chlorine dioxide, the incidence increasing in a dose-related manner. The calculated mean LC50 was 32 ppm (90 mg/m3). In another study, ocular discharge, nosebleeds, pulmonary oedema, and death occurred at 260 ppm (728 mg/m3) for 2 h. Chlorine dioxide is toxic when administered in solution by a single oral dose to rats; at 40 and 80 mg/kg body weight, there were signs of corrosive activity in the stomach and gastrointestinal tract. The calculated oral LD50 was 94 mg/kg body weight.Data on the eye and respiratory tract irritancy of chlorine dioxide gas are limited in extent. However, there is evidence for eye and respiratory tract irritation in humans associated with unknown airborne levels of chlorine dioxide gas. Severe eye and respiratory tract irritancy has been observed in rats exposed to 260 ppm (728 mg/m3) for 2 h.There are no reports of skin sensitization or occupational asthma associated with chlorine dioxide.The quality of the available repeated inhalation exposure data in animals is generally poor, such that the information on dose–response must be viewed with some caution. In addition, there is concern that the nasal tissues were not examined, although rhinorrhoea was reported in one study in rats at 15 ppm (42 mg/m3), indicating that the nasal passages may be a target tissue for inhaled chlorine dioxide. Other rat studies indicated that no adverse effects were reported at 0.1 ppm (0.28 mg/m3) for 5 h/day for 10 weeks or at 1 ppm (2.8 mg/m3) for 2–7 h/day for 2 months. Lung damage, manifested by bronchitis, bronchiolitis, or small areas of haemorrhagic alveolitis, appearsto develop at 2.5 ppm (7.0 mg/m3) or more following repeated exposure for 7 h/day for 1 month and at 10 ppm (28 mg/m3) or more for 15 min twice per day for 4 weeks, with dose-dependent severity. Mortalities occurred following exposure at 15 ppm (42 mg/m3) for 15 min, 2 or 4 times per day, for 1 month. In the same exposure regime, there were no adverse effects reported (among the limited observations performed) at 5 ppm (14 mg/m3).The results of repeated oral exposure studies in rats and primates are generally of limited design and/or quality but show no evidence of systemic toxicity associated with chlorine dioxide administered in the drinking-water or by gavage. There are no data in relation to chronic exposure to or carcinogenicity of chlorine dioxide gas.Studies in mammalian cells using aqueous solutions of chlorine dioxide indicate that chlorine dioxide is an in vitro mutagen. This activity was not expressed in well conducted studies in vivo in somatic or germ cells. However, given the generally reactive nature of this substance and the fact that positive results have been produced in vitro, there is cause for concern for local "site-of-contact" mutagenicity, although no studies have been conducted for this end-point.Oral exposure to chlorine dioxide at parentally toxic levels in rats does not impair fertility or development. This is consistent with the view that as chlorine dioxide is a reactive gas, it would be unlikely to reach the reproductive organs in significant amounts.The available measured occupational exposure data (in the United Kingdom) and the exposure levels predicted using the Estimation and Assessment of Substance Exposure model indicate a maximum likely exposure of 0.1 ppm (0.28 mg/m3), 8-h TWA. Comparison of this exposure level with the no-observed-adverse-effect level (NOAEL), which is derived from very limited data, suggests that there is no cause for concern in relation to the development of irritation of the respiratory tract or of the eyes in workers occupationally exposed to chlorine dioxide.Insufficient data are available with which to conduct an environmental risk assessment. Chlorine dioxide would be degraded rapidly in the environment to yield chlorite and chlorate. The few ecotoxicity data available show that chlorine dioxide can be highly toxic to aquatic organisms; the lowest reported LC50 for fish was 0.02 mg/litre. Chlorate, released in pulp mill wastewaters following use of chlorine dioxide, has been shown to cause major ecological effects on brackish water communities. Brown macroalgae (seaweeds) are particularly sensitive to chlorate following prolonged exposure. The threshold for effects is between 10 and 20 µg/litre.2. IDENTITY AND PHYSICAL/CHEMICAL PROPERTIESChlorine dioxide (ClO2, Chemical Abstracts Service [CAS] No. 10049-04-4), a free radical, exists as a greenish yellow to orange gas at room temperature with a characteristic pungent chlorine-like odour. Chlorine dioxide gas is strongly oxidizing; it is explosive in concentrations in excess of 10% v/v at atmospheric pressure and will easily be detonated by sunlight or heat (Budavari et al., 1996). Its melting point is -59 °C, its boiling point is 11 °C (at 101.3 kPa), and its vapour densityis 2.34 (air = 1).Owing to the difficulties in transportation associated with the explosive nature of aqueous solutions of chlorine dioxide, marketed products are usually stabilized by the addition of substances such as sodium hydrogen carbonate, which leads to the formation of an aqueous sodium chlorite solution rather than chlorine dioxide. However, chlorine dioxide is then generated at the site of intended use by a displacement reaction (such as by the addition of an acid). Its solubility in water is 3 g/litre at 20 °C, and its specific gravity is 1.642 (Budavari et al., 1996).Some of the more commonly used synonyms for chlorine dioxide include chlorine oxide, chlorine peroxide, chloroperoxyl, chlorine(IV) oxide, and chlorine dioxide hydrate.The chemical structure of chlorine dioxide is shown below:·O=Cl=O·The conversion factor for chlorine dioxide in air at 20 °C and 101.3 kPa is 1 ppm = 2.8 mg/m3.Additional physical/chemical properties are presented on the International Chemical Safety Card (ICSC 0127) reproduced in this document.At room temperature and pressure, the natural form of chlorine dioxide is a gas that is unstable, highly reactive (an oxidizing agent), and explosive. Consequently, very few toxicological studies are available that relate to the gaseous form. Some studies have been conducted via the oral route using aqueous solutions of chlorine dioxide. Several of these studies were conducted using "stabilized aqueous chlorine dioxide," sometimes by maintaining a constant pH using sodium carbonate and sodium hydrogen carbonate. However, it is recognized that this would effectively lead to the formation of aqueous sodium chlorite (which can subsequently generate chlorine dioxide by acid displacement). These studies are felt to be less relevant than those using stabilized aqueous chlorine dioxide and are not summarized in this review. The reasons for this are that chlorine dioxide dissolves discretely in water (i.e., it does not dissociate into ions), forming a solution of around pH 5 or less, whereas an aqueous solution of sodium chlorite has a different, ionized composition and a pH of approximately 8. The explosive nature of this substance has limited the concentration of chlorine dioxide in aqueous solutions to a maximum of about 1% w/v.3. ANAL YTICAL METHODS3.1 Workplace air monitoringThe US Occupational Safety and Health Administration (OSHA) has published Method ID 202, "Determination of chlorine dioxide in workplace atmospheres" (Björkholm et al., 1990; OSHA, 1991; Hekmat et al., 1994). This describes a method for making personal exposure measurements of chlorine dioxide. Samples are collected by drawing air through a midget fritted glass bubbler, or impinger, containing 0.02% potassium iodide in a sodium carbonate/sodium bicarbonate buffersolution, at a flow rate of 0.5 litres/min. Chlorine dioxide is trapped and converted to chlorite (ClO2–), which is subsequently measured by suppressed ion chromatography using a conductivity detector. The method has a reported detection limit of 0.004 ppm (0.011 mg/m3) for a 4-h sampling time and 0.06 ppm (0.17 mg/m3) for a 15-min sampling time. However, it is recommended that a sampling time of less than 1 h be used in order to avoid possible negative interference from chlorine and acid gases.3.2 Biological monitoring in humansBecause of the rapid formation of chloride ions following absorption of chlorine dioxide and the high normal, physiological levels of chloride in biological fluids, biological monitoring cannot detect occupational exposure to chlorine dioxide. Hence, there are no published biological monitoring methods available for chlorine dioxide.4. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSUREThe most significant uses of chlorine dioxide worldwide appear to be in bleaching paper pulp and cellulose. However, owing to the nature of the source document of this CICAD (Health and Safety Executive, 2000), this section focuses mainly on the production of chlorine dioxide.Potential occupational exposure to chlorine dioxide gas may occur during its manufacture, during charging of the aqueous solution into drums, and during its use as a sterilizing agent in hospitals, as a biocide in water treatment, and as an improving agent in flour (Health and Safety Executive, 2000). There will also be potential exposure to aerosol if aqueous solutions of chlorine dioxide are agitated or splashed, such as may occur during the charging of drums. During manufacture and subsequent captive use of the gas, good process plant control is essential because of the explosive nature of the gas. Furthermore, once the gas is absorbed in water, it has a low volatility. For these reasons, inhalation exposure is anticipated to be minimal.Additional uses are reported in bleaching flour, leather, fats and oils, textiles, and beeswax; water purification and taste and odour control of water; cleaning and detanning leather; and manufacture of chlorate salts, oxidizing agents, bactericides, antiseptics, and deodorizers (Budavari et al., 1996). However, no exposure data are available for these uses.It is estimated that up to 1400 tonnes of aqueous chlorine dioxide are used per year in the United Kingdom (Health and Safety Executive, 2000). In North America (USA and Canada), the estimated production in 1980 was 243 000 tonnes per year, and in 1990, it was around 509 000 tonnes per year (Clayton & Clayton, 1994). In Sweden, approximately 75 000 tonnes per year were manufactured (principally in pulp mills) in 1992 (Landner et al., 1995).Release to the environment is almost exclusively to the air. The US Toxic Release Inventory reports total releases of chlorine dioxide in 1996 at approximately 550 tonnes to the atmosphere, of which more than 98% was via stacks and the remainder fugitive air releases. The majority of reported releases were from use of chlorine dioxide in pulp bleaching, with the remainder in foodprocessing.5. ENVIRONMENTAL TRANSPORT, DISTRIBUTION,AND TRANSFORMATIONChlorine dioxide is readily volatilized from aqueous solution at between 10 °C and 15 °C (Budavari et al., 1996). It is quite stable in solution if kept cool, in the dark, and in a closed vessel. Chlorides in solution catalyse decomposition, even in the dark. V olatilized chlorine dioxide decomposes to chlorine and oxygen with noise, heat, flame, and a minor pressure wave at low concentrations; it decomposes explosively at >40 kPa partial pressure.At pHs between 4.8 and 9.8, up to 50% of chlorine dioxide is hydrolysed to chlorite. A chlorite concentration of 0.72 mg/litre was obtained following treatment with chlorine dioxide at 1.5 mg/litre (Moore & Calabrese, 1980).Use of chlorine dioxide in pulp mills leads to the formation of chlorate. This is reduced to chloride in treatment plants, where present (Landner et al., 1995).6. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE6.1 Environmental levelsNo data are available on levels of chlorine dioxide in the environment. Chlorine dioxide would be degraded in the environment to yield chlorite and chlorate in water, so no water concentrations of chlorine dioxide are expected. However, almost all release is to the atmosphere, with decomposition to chlorine and oxygen.6.2 Occupational exposureThe main source of occupational exposure worldwide would appear to be from the paper and pulp industry. Limited data are available, although one review (Jappinen, 1987) quotes ranges in pulp bleaching of 0–2 ppm (0–5.6 mg/m3) (from Ferris et al., 1967; measured data were from around 1958, although it was not clear if these were from personal monitoring or static samples) and more recent (1965–1972) measurements by the Finnish Institute of Occupational Health of <0.1–2.5 ppm (<0.28–7.0 mg/m3).Limited occupational exposure data were received from one manufacturer of the gas. The data indicated that all personal exposures during drum charging were below 0.1 ppm (0.28 mg/m3) 8-h TWA and 0.3 ppm (0.84 mg/m3) 15-min reference period (Health and Safety Executive, 2000).Limited occupational exposure data were also received from companies using the substance as a biocide in hot and cold water systems and as a sterilizing agent in hospitals. No data were received from firms using it for reducing foul smells and odours in water treatment. During its use as a sterilizing agent in hospitals, all occupational exposures were found to be well below 0.1 ppm。
《医院污水处理二氧化氯消毒风险评价》
第五章风险分析建设项目涉及风险事件有突发传染病流行事件、污水站有毒有害物质泄露事件。
国家及XX省卫生部门针对各类突发传染病均制定相应的应急预案并且XX市城区设有专门的传染病医院——XX市第五医院、XX（区）结核病防治所，急性传染病（SARS、人禽流感、猪流感）均送XX市第五医院治疗，结核病人送XX市（区）结核病防治所其他医院不设置治疗科室。
建设项目可按照相应方案执行。
本报告给出污水站事故应急预案。
5.1 物质危险性分析建设项目涉及的危险物质包括盐酸、二氧化氯、麻醉药品和精神药品等。
建设项目均利用现有盐酸储罐、二氧化氯发生器和麻醉药品、精神药品的储运设施，只在使用量有所增加，周转频次增加。
盐酸和二氧化氯的具体性质见表1-14、表1-15。
5.2 风险识别5.2.1 风险等级确定根据1.6节可知风险评价等级为一级。
5.2.2 环境影响区域敏感目标识别对以项目为中心半径5km区域内的敏感点进行调查，该范围包括XX市城区主要建筑区，将主要建筑及敏感点列于表5-1及图1-5。
表5-1 建设项目风险评价敏感点一览表5.3 生产过程中的潜在危险性麻醉药品、精神药品为治疗用药，并且医院有完善的处方、购买、进出库管理制度。
二氧化氯水溶液的浓度在8~10克/升，将产生引起爆炸危险的高压蒸汽；本项目污水站消毒使用二氧化氯量38-57克/立方米污水，远低于8~10克/升；二氧化氯发生器中二氧化氯产生量为2.85kg/h。
二氧化氯发生器运行压力为常压；二氧化氯全部泄露，污水站内二氧化氯的浓度约为3.8%（V/V），小于爆炸浓度10%（V/V）。
综上所述本项目生产过程中的潜在危险事故为盐酸储罐泄露和二氧化氯全部泄露对周围环境空气的影响及危害，根据建设污水站生产特点，分析其生产过程潜在的风险事故因素，详见表5-2。
表5-2 盐酸储罐潜在环境风险因素一览表根据《建设项目环境风险评价技术导则》（HJ/T169－2004）和《重大危险源辨识》（GB18218-2009）判定其不构成重大危险源。
如何全面评价二氧化氯片的质量(二)
根据亚氯酸钠按照实际 生成的二氧化氯占理论值的百分比计算：
五步碘量法和紫外分光光度法测 得的真正的二氧化氯高，不代表二氧 化氯的转化率高。五步碘量法和紫外 分光光度法测得的真正的二氧化氯含 量近似，不代表二氧化氯的转化率也 近似。
通过五步碘量法，测出反应体系中ClO2、Cl2、ClO2-、ClO3-各自的质量-体积 浓度值（单位：mg/L），然后通过生成的二氧化氯的质量-体积浓度值和未反应 的亚氯酸钠质量-体积浓度值来计算：
二氧化氯泡腾片是指在组方中加入泡腾崩解剂，片入水后，迅速崩解，即 刻发生泡腾反应，大大促进了组方中各成分在水中的溶解和扩散。泡腾时产生 的大量气泡，可以将反应生成的二氧化氯送入中上层水域，可以起到立体消毒 的效果。 在亚氯酸钠（或氯酸钠）和活化剂的添加量相同的情况下，泡腾片剂型有着 起效快，在水体不同水层中扩散均匀的特点，适合疾病爆发或水体突然恶化时的 紧急急救。 缓释片的特点和用途 二氧化氯缓释片，是指在组方中加入钝化剂、隔离剂或使用包被技术，控制
对于一元二氧化氯片来说，并不 是含量越高质量越好。一元二氧化氯 片的含量是由组方中亚氯酸盐或氯酸 盐、酸的量和转化率决定的，亚氯酸 盐或氯酸盐和酸的量越高，相应产品
2017年第7期
81
健康 养殖
表3 不同配方的二氧化氯片二氧化氯含量和转化率的检测结果 检测方法 含量（间接碘量法），% 含量（五步碘量法），% 含量（紫外分光光度法），% 转化率，% 样品1 8.56 7.99 8.13 96.50 样品2 8.38 6.35 6.59 89.22 样品3 8.96 3.49 3.52 56.25 样品4 6.05 5.88 5.92 99.13
图2.泡腾片的特点和用途
部崩解溶散所需时间的限度。 （ 1 ）崩解时限并不等同于反应 生成二氧化氯需要的时间。 （ 2 ）崩解速度快也并不等同于 亚氯酸盐（氯酸盐）转化成二氧化氯 的反应速度快。 （ 3 ）二氧化氯片在水中崩解完 全时并不能说明反应体系中生成的二 氧化氯浓度达到峰值。 二氧化氯标准溶液制备时（直接 光度法测定高浓度二氧化氯消毒液 .
含氯消毒液浓度不合格整改后效果评价
含氯消毒液浓度不合格整改后效果评价含氯消毒液是一种常见的消毒杀菌剂，广泛应用于各种场所和行业，如医疗机构、食品加工厂、公共场所等。
然而，由于制作和使用过程中的各种原因，含氯消毒液的浓度可能会不合格。
本文将深入探讨含氯消毒液浓度不合格后的整改效果评价，并分享我的观点和理解。
1. 整改前的问题：浓度不合格的危害在消毒过程中，消毒液的浓度与其杀菌效果密切相关。
如果含氯消毒液的浓度不合格，可能导致以下问题：- 杀菌效果下降：低浓度的消毒液可能无法有效杀灭病毒、细菌和其他病原微生物，从而无法达到预期的消毒效果。
- 食品安全风险：在食品加工过程中，使用浓度不合格的消毒液可能无法彻底去除有害菌群，使得食品受到污染，引发食源性疾病。
- 医疗安全隐患：在医疗机构中，低浓度的消毒液可能无法有效消灭手术器械和环境表面上的病原菌，增加手术感染和交叉感染的风险。
2. 整改措施：提高浓度的方法针对含氯消毒液浓度不合格的问题，可以采取以下整改措施：- 检查消毒剂供应商：确保消毒剂供应商符合相关的生产和质量管理标准，提供稳定和合格的产品。
- 建立严格的质量控制程序：制定严格的消毒液配制标准和操作规程，确保每批次消毒液符合要求的浓度。
- 提高员工培训水平：培训员工正确使用消毒液、掌握配制和稀释方法，并加强对浓度检测工具的正确使用和维护培训。
- 加强监管和检测：加强对消毒液浓度的监管和检测，建立有效的监测体系，定期对消毒液进行抽样检测。
3. 整改后效果评价：总结和回顾进行了浓度不合格的含氯消毒液整改后，我们需要对整改效果进行评价。
评价过程应包括以下几个方面：- 浓度合格率：通过抽样检测，测定整改后的含氯消毒液浓度是否符合相关标准。
合格率的提高可以反映出整改效果的好坏。
- 杀菌效果：对整改后的含氯消毒液进行杀菌效果测试，比较其与浓度不合格时的差异。
通过实验方法，可以评估整改后消毒液的杀菌效果是否满足需求。
- 安全风险：观察整改后的食品加工厂或医疗机构是否出现食源性疾病或交叉感染等问题，评估整改措施对安全风险的控制效果。
水厂二氧化氯风险评估
环境风险评价1.风险识别1.1风险物质识别根据《危险化学品名录》中的规定，本项目净水工艺过程中涉及到的危险品为液氯。
其可能对人体造成的伤害分析如下：理化性质：黄绿色有刺激性气味的气体。
熔点-101℃，沸点-34.5℃，相对密度( 水=1)1.47 ，相对密度( 空气=1)2.48 。
易溶于水、碱液。
健康危害：对眼、呼吸道粘膜有刺激作用。
急性中毒：轻度者有流泪、咳嗽、咳少量痰、胸闷，出现气管炎的表现；中度中毒发生支气管肺炎或间质性肺水肿，病人除有上述症状的加重外，出现呼吸困难、轻度紫绀等；重者发生肺水肿、昏迷和休克，可出现气胸、纵隔气肿等并发症。
吸入极高浓度的氯气，可引起迷走神经反射性心跳骤停或喉头痉挛而发生“电击样”死亡。
皮肤接触液氯或高浓度氯，在暴露部位可有灼伤或急性皮炎。
慢性影响：长期低浓度接触，可引起慢性支气管炎、支气管哮喘等；可引起职业性痤疮及牙齿酸蚀症。
侵入途径：吸入。
危险标记：6（有毒气体）1.2风险单元的识别在整个加氯过程中大多数设备都是在部分真空下工作的，一般情况不易产生氯气的泄漏。
根据类比调查，氯气泄漏的原因主要是换瓶时操作不当，管道使用时间过长而破损，阀门连接部件垫圈受损及阀门质量不高等引起，其中较为常见的是在换瓶时，由于操作失误引起紫铜管中留有的少量液氯的泄漏。
一般的加氯消毒工艺如图3。
液氯钢瓶液氯管路蒸发器流量计流量计控制阀溶氯器清水池图3加氯消毒工艺流程图3 2.环境风险防范措施2.1操作过程中的安全防范措施为使环境风险减小到最低限度， 必须加强劳动安全卫生管理， 制定完备的安全防范措施，尽可能降低项目环境风险事故发生的概率。
生产操作过程中，必须加强安全管理，提高事故防范措施。
加氯设备必须配备相应的报警系统，配备自动喷水系统等应急预防设施，一旦发生事故性泄漏， 报警系统即会自动报警 (报警浓度为1ppm(0.3158mg/Nm))，并可开启机械通风设备，抽取含氯空气，再经喷淋设备处理后排空。
（水厂）ClO2消毒水质效果影响因素分析及运行风险控制
（水厂）ClO2消毒水质效果影响因素分析及运行风险控制发布时间：2022-04-11T09:33:50.474Z 来源：《中国科技信息》2022年1月上作者：王东包均纲[导读] 为防止通过饮用水传播疾病，在常规水处理中，消毒是必不可少的关键环节。
消毒并非消灭水中全部微生物，只是消除水中致病微生物的致病作用。
水的消毒方法很多，对于传统和普遍的氯消毒方式，由于运行年限较久，系统多项安全指标不能满足新标准要求，运行系统、辅助建构筑物设施、维护管理等多方面出现严重的安全隐患。
为提高生活水水质，以及职工、居民的生活质量，保证人们身体健康，新工艺采用了消毒效果更强，应用较为成熟的ClO2消毒工艺。
中核兰州铀浓缩有限公司王东包均纲甘肃兰州 730065【摘要】：为防止通过饮用水传播疾病，在常规水处理中，消毒是必不可少的关键环节。
消毒并非消灭水中全部微生物，只是消除水中致病微生物的致病作用。
水的消毒方法很多，对于传统和普遍的氯消毒方式，由于运行年限较久，系统多项安全指标不能满足新标准要求，运行系统、辅助建构筑物设施、维护管理等多方面出现严重的安全隐患。
为提高生活水水质，以及职工、居民的生活质量，保证人们身体健康，新工艺采用了消毒效果更强，应用较为成熟的ClO2消毒工艺。
在生产中，用ClO2进行饮用水消毒时，水质会受到多方面因素的影响，消毒效果呈现一定的差异。
经研究，在其他条件（混凝、沉淀、过滤）一定的情况下，水质效果与消毒剂的使用密切相关，其中消毒效果与水中ClO2含量呈正相关关系，在一定范围内，水中ClO2含量的多少直接代表着消毒效果的好坏。
尽管ClO2消毒工艺比之其他消毒工艺有着诸多的优势，但其生产、运行过程存在着一定的安全风险，使用过程中需格外注意。
本文对饮用水ClO2消毒效果影响因素及系统运行风险进行分析，以期为提高饮用水供水水质及管理水平提供参考。
【关键字】：ClO2；消毒效果；影响因素；风险；控制 1.选题的背景和意义二氧化氯作为消毒剂，对细菌的细胞壁有较强的吸附和穿透能力，故ClO2对细菌、病毒等有很强的灭活能力。
二氧化氯消毒剂发生器安全性评估指南
二氧化氯消毒剂发生器安全性评估指南
1. 简介
本文档旨在提供二氧化氯消毒剂发生器的安全性评估指南，以
确保其在使用过程中的安全性和有效性。
2. 背景
二氧化氯消毒剂发生器是一种常用于消毒和杀菌的设备。
然而，在使用过程中，如果不正确操作或维护，可能会带来安全风险。
因此，对于这种设备的安全性评估至关重要。
3. 安全性评估步骤
3.1 设备检查
在开始使用二氧化氯消毒剂发生器之前，应进行全面的设备检查，包括但不限于以下方面：
- 设备外观是否完好；
- 电气部件是否正常运作；
- 过滤器是否清洁。
3.2 操作指南
在操作二氧化氯消毒剂发生器时，应遵循以下指南：
- 完整阅读并理解设备操作手册；
- 正确设置和使用设备的控制参数；
- 避免设备超载或过热；
- 配戴适当的个人防护装备。
3.3 维护与保养
为确保设备的持久安全性和性能，应注意以下事项：
- 定期清洁和消毒设备；
- 定期检查设备的电气和机械部件；
- 更换耗材和零部件时，应选择合适的原厂配件。
4. 应急处理
在发生设备故障或意外情况时，应采取以下紧急处理措施：- 立即停止设备运行；
- 断开电源或关闭相关阀门；
- 疏散周围人员，并保持安全距离；
- 如有需要，立即通知相关维修人员。
5. 结论
本文档提供了二氧化氯消毒剂发生器安全性评估的指南，包括设备检查、操作指南、维护与保养以及应急处理措施。
通过遵循这些指南，可以确保设备的安全性和可靠性，提高工作场所的卫生水平。
氧化剂使用风险评估报告
氧化剂使用风险评估报告1. 引言本报告旨在对氧化剂在使用过程中的风险进行评估和分析，以便于制定相应的风险管理措施，确保人员和环境的安全。
本评估报告将主要涵盖氧化剂的性质、常见的使用方式、潜在的危险性以及风险管理建议。
2. 氧化剂的性质氧化剂是一类具有氧化能力的物质，常常用于促进或加速其他物质的氧化反应。
其特性包括高氧化能力、较高的燃烧性、易与燃料反应等。
常见的氧化剂有过氧化氢、高锰酸钾、硝酸等。
3. 氧化剂的常见使用方式氧化剂在工业、实验室和其他相关行业中有广泛的使用。
常见的使用方式包括但不限于：- 作为催化剂促进化学反应；- 用于清洁、漂白和消毒；- 用于发动机燃料或推进剂；- 作为氧气剂使用于医学行业；- 用于制备爆炸物等特定应用。
4. 氧化剂的潜在危险性氧化剂使用过程中存在一定的潜在危险性，需要引起关注。
主要的风险包括但不限于：- 燃烧和爆炸风险：氧化剂具有较高的燃烧性，与易燃物质接触可能引发火灾或爆炸；- 毒性风险：某些氧化剂可导致中毒，对人体健康产生危害；- 腐蚀性风险：部分氧化剂具有强腐蚀性，可能对皮肤、眼睛等造成损害；- 不稳定性：某些氧化剂可能在特定条件下发生不稳定反应，进一步放大危险。
5. 风险管理建议为了降低氧化剂使用过程中的风险，以下措施和建议值得注意：- 确保安全储存：氧化剂应储存在专用的、密闭的储存区域内，远离易燃和可燃物质，避免直接日晒和高温；- 正确使用和操作：使用氧化剂时应遵循正确的操作程序和安全指南，佩戴适当的防护设备，保护眼睛、皮肤等易受损部位；- 防火防爆措施：与易燃物质同时使用时需采取防火和防爆措施，保持通风良好，避免火源；- 废弃物处理：废弃物应按照相关法规和规定进行分类、储存和处置，避免污染环境；- 应急处置预案：建立应急处置预案，包括泄露、火灾、爆炸等突发情况的处理方法和紧急联系方式。
6. 结论氧化剂的使用潜在危险性需要得到足够的重视和管理。
通过正确的储存、操作和处置，可以最大限度地减少与氧化剂相关的事故和损害。
二氧化氯区域安全隐患分析与改进
二氧化氯区域安全隐患分析与改进发表时间：2019-07-25T10:49:02.877Z 来源：《科技新时代》2019年5期作者：刘奕强[导读] 提高现场防护设施、对二氧化氯发生器进行更新、对计量罐进行更换等，较好的解决了现场存在的隐患，保障了二氧化氯系统的稳定运行。
（扬子石化分公司水厂江苏南京 210048）摘要：介绍了二氧化氯区域存在问题，阐述并分析二氧化氯区域存在隐患及产生问题的原因，提出进一步加强对岗位人员现场培训，规范原料进出，及时更新二氧化氯发生器，对计量罐进行更换，解决了现场存在隐患，确保了二氧化氯系统的安全稳定运行。
关键词：二氧化氯盐酸亚氯酸钠隐患对策1、概述水厂供水装置于2006年投用二氧化氯装置，主要目的是对生活水进行消毒，提高生活水水质。
二氧化氯制备技术采用25％的亚氯酸钠水溶液和31％的盐酸进行反应，属于高效生产二氧化氯方法，该方法有二氧化氯纯度高，副产物少等优点，反应原理图见“式1”。
5NaClO2+4HCl 5NaCl+4ClO2+2H2O式1 反应方程式由于该二氧化氯区域盐酸、亚氯酸钠均为危险化学品、生成的二氧化氯也具有强腐蚀性，当水溶液中二氧化氯含量大于30%，会发生爆炸［1］，因此该区域隐患多，问题多对二氧化氯系统的长期稳定运行造成了影响。
2、问题提出2.1 人的不安全因素2.1.1 原料及产品对操作人员的影响由于该反应中采用两种原料，一种为盐酸；另一种为亚氯酸钠，其中盐酸为无色或稍呈黄绿色的透明水溶液，在空气中发烟，具有刺激性气味且有腐蚀性。
亚氯酸钠呈碱性，遇酸易分解放出二氧化氯气体。
亚氯酸钠水溶液仅对许多有机化合物起局部、缓慢的氧化作用。
2.1.2、操作不当对操作人员的影响二氧化氯产品具有强刺激性和一定浓度下爆炸的特性，因此操作人员在操作过程中要严格按照操作规程进行操作，由于盐酸与亚氯酸钠接触后会发生剧烈放热反应，因此首先要避免进错料；其次还要注意盐酸具有较强腐蚀性、挥发性，要避免由于操作不当人员受到伤害、设备设施出现泄漏或爆炸。
2024年二氧化氯的安全操作及危害（2篇）
2024年二氧化氯的安全操作及危害黄绿色或黄红色气体。
有类似氯气和硝酸的特殊刺激臭味。
液体为红褐色，固体为橙红色。
熔点-59℃。
沸点11℃。
气体密度3.09g/L。
易溶于水，溶于碱溶液、硫酸。
具有强氧化性，其有效氯是氯的2.6倍，与很多物质都能发生剧烈反应。
腐蚀性很强。
二、危险性⒈遇热水则分解成次氯酸、氯气、氧气，受光也分解，其溶液在冷暗处十分稳定。
受热或受光照或遇有机物等能促进氧化作用的物质时，能促进分解并易引起爆炸。
若用空气、二氧化碳、氮气等惰性气体稀释时，爆炸性降低。
⒉具有强烈刺激性。
接触后主要引起眼和呼吸道刺激,引起咳嗽、喷嚏、气急、胸闷以及流涕、流泪等眼、鼻、咽喉部刺激症状及体征。
吸入高浓度可发生肺水肿。
国外曾报告过2例急性中毒，其中死亡1例，空气中本品的浓度低于51mg/m3。
长期接触可导致慢性支气管炎。
皮肤接触高浓度溶液，可引起强烈刺激和腐蚀。
三、主要用途常用的二氧化氯溶液的浓度为8～10g/L，主要用于纸浆和纸、纤维、小麦面粉、淀粉的漂白，油脂、蜂蜡等的精致和漂白，引用水的消毒杀菌处理。
四、安全操作指南⒈包装可用聚氯乙烯桶包装，每桶净重20L或100L。
也可用钢瓶包装。
包装容器的桶身上应加贴化学品安全标签，标签的编写应符合国家标准《化学品安全标签编写规定》（GB15259-xx）。
包装上应明显注明怕热标志。
⒉运输铁路运输时应严格按照铁道部《危险货物运输规则》中的危险货物配装表进行配装。
采用刚瓶运输时必须戴好钢瓶上的安全帽。
钢瓶一般平放，并应将瓶口朝同一方向，不可交叉；高度不得超过车辆的防护栏板，并用三角木垫卡牢，防止滚动。
严禁与易燃物或可燃物、还原剂、食用化学品等混装混运。
夏季应早晚运输，防止日光曝晒。
公路运输时要按规定路线行驶，禁止在居民区和人口稠密区停留。
铁路运输时要禁止溜放。
应使用危险品运输车辆运输。
运输时运输车辆手续证件齐全，符合国家标准或法律法规对安全的要求；运输和押送人员应进行相应的专业技术、安全知识和应急救援的培训，要了解所运载危险品的性质、危害性和发生意外时的应急措施。
化学物风险评价
作业场所化学因素风险评价风险指导致某种结果的事件发生的可能性大小。
不同的化学品具有不同的特性和毒性。
暴露于有毒化学品可引起不同危害，取决暴露途径和水平。
有毒或有害化学品的风险评价用以确定有毒或有害化学物对使用者所造成的风险水平，同时可判定是否需要对化学品采取相应防护措施或个人防护用品以保护接触者的健康。
建设单位或业主应采取有效措施确保化学品的安全使用。
因此，为识别、评价和控制生产作业中由于接触化学品所产生的健康危害，作业场所使用的化学品都应进行风险评价。
一、评价目的对有害化学品进行风险评价有以下几个目的：1.识别每一种使用或处理的化学品可能产生的危害；2.评价暴露有毒或有害化学品的程度；3.判定因暴露化学品所产生不良影响的可能性的大小。
评价的最终结果是为了对可能产生暴露危害的不同作业进行风险分级，以便根据不同危害级别采取相应措施以达到减少风险的目的。
二、风险评价的适用范围风险评价方法的适用范围如下：1仅涉及工作场所使用的化学品对作业人员健康的风险；2适用于工厂中使用的有毒或有害化学品，包括原材料、产品、组分及副产品；3决定参与评价工作的人员组成和何种作业需要评价；4.制定风险评价的工作程序图；5.明确评价后所应采取的相应措施及对记录评价、重新实施评价的要求；6.适用于健康、安全管理者及其他可能从事风险评价的人员；7.本方法不适用因生产设备和控制系统发生故障所引起的事故；8.不适用于对周围人群、公众或环境的风险评价；9.没有考虑高危人群；10.没有考虑经皮吸收（另有公式可估计经皮吸收水平）及经口摄入等暴露途径。
三、半定量风险评价方法风险评价常采用半定量的评价方法，包括：系统地对化学品危害进行识别、评价暴露或暴露的可能性，判定风险水平及基于风险大小所应优先采取的控制措施等。
风险评价的半定量方法常包括以下11个步骤（程序见图1）：1组建评价小组；2分解作业过程；3识别涉及的化学品；4确定化学品的危害级别；5.进行职业卫生现场调查；6.获得暴露频率和每次暴露时间的有关资料；7.判定暴露级别；&评价风险大小；9.采取适当措施；10.记录评价；口重新实施评价。
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－专项评价2－环境风险评估环境风险评估的目的就是通过分析污水处理厂运营期内可能发生的事故类型及其影响程度和范围，以确定开发建设及生产项目什么样的风险是社会可以承受的，从而为工程设计提供参考依据。
污水处理厂具有一定的事故风险性，需要进行必要的环境事故风险分析，提出进一步降低事故风险措施，使得污水处理厂在生产正常运转的基础上，确保污水处理厂内外的环境质量，确保职工及周边影响区内人群生物的健康和生命安全。
1环境风险识别及分析1.1物质危险性识别（1）本项目存在的主要危险、有害的物质本项目存在的主要的危险、有害原料及中间产品的理化性质及毒理性质见表1。
表1 主要危险、有害原料及物质的理化性质及毒理性质（2）危险特性识别本项目存在的风险主要为：①氯酸钠与有机物发生氧化反应放热，引发火灾；强氧化剂氯酸钠遇酸反应产生大量氯，氯酸在40℃以下就会发生爆炸。
②盐酸泄露对周围的物体造成腐蚀或对人员的灼伤。
1.2生产、辅助设备风险性识别结合本项目生产工艺的特点，本项目可能存在风险主要有：①锅炉除尘、脱硫设备发生故障时，对大气造成污染。
②污水核心处理设备发生故障时，对地表水造成的污染。
2环境风险评价等级、评价范围及风险保护目标2.1评价等级结合以上环境风险识别分析，项目所在地位于通辽市边缘，周围居民、企业稀少，所以为非环境敏感区；本项目主要原辅材料基本无毒，储存量没有超过导则规定的贮存场所临界量，因此本项目风险源为非重大风险源。
按照《建设项目环境风险评价技术导则》中的要求，本环境风险评价为二级，见表2。
根据导则要求二级评价可进行风险识别、源项分析和对事故影响进行简要分析，提出防范、减缓和应急措施。
2.2评价范围本项目风险评价等级定为二级评价，根据《环境风险评价技术导则》大气环境风险评价范围为距点源4×6Km2范围内。
地表水风险评价范围为排污口下游30km内，选择CODcr 为预测因子。
和BOD52.3环境风险保护目标根据建设项目所在区域的生态环境（包括：水体、陆域生态特征、社会经济状况、城镇及人口分布、工农业分布。
见工程分析专项）确定风险评价的重点保护目标，见表3。
表3 风险保护目标表3源项、源强分析3.1最大可信事故概率分析根据工程分析，确定本项目风险源为生产装置区以及原材料和产品储存区。
主要表现在以下几个方面：➢锅炉除尘设备发生故障，导致粉尘直接排入大气；➢锅炉脱硫设备发生故障，导致烟气直接排入大气；➢污水核心处理设备发生故障，导致污水未经处理而外排；➢氯酸钠、盐酸贮存库发生火灾事故；➢由于火灾而产生的消防废水。
3.2一般事故统计资料查阅近几年国内污水处理厂运营期间发生的事故，其发生概率很低，2004年3月19日深圳龙岗布吉污水厂，由于一根污水管脱落，使污水厂周围被污水淹没。
所以全国污水处理厂按600家计，则近5年污水厂发生事故的概率为0.03%。
其它污水厂事故包括2005年12月16日正在建设中的石家庄桥东污水厂发生坍塌，以及2006年6月1日河北唐山污水处理厂发生的落水事故，则不属运营期发生的范畴。
通过对国内类似化工行业事故发生原因的调查统计，化工行业以设备、管道、贮罐破损泄漏等引起的事故出现比例最高，而造成设备破损泄漏的直接原因多为管理不善、未能定时检修造成。
以违反操作规程、操作失误以及不懂技术操作等人为因素引起的事故出现的比例较高。
表4给出我国化工企业一般事故原因统计。
表4 我国化工企业一般事故原因分类结合本项目生产工艺的特点，估计本项目环境风险事故发生的概率如表5：表5 本项目一般事故原因统计从表5中可以看出，本项目事故发生的主要原因为设备发生故障和废气处理设施发生故障，其发生概率分别为60%和4%。
3.3事故风险源项源强污染物事故排放源强详见表6。
4事故风险预测4.1废水处理事故排放影响分析（1）预测模式采用河流完全混合模式如下：式中：C o—河水完全混合后河流中污染物浓度，mg/L；Cp—污水排放浓度，mg/L；Qp—污水排放量，m3/s；Ch—河流对照断面污染物浓度，mg/L；Qh—河流上游流量，m3/s。
非持久性污染物充分混合段预测模式如下：式中：C x—河流下游X处污染物预测浓度，mg/L；K—污染物自净系数，1/d；X—充分混合点至预测点河段距离，m；u—河流流速，m/s；C o—充分混合点河流中污染物浓度，mg/L。
计算公式同上。
（2）污水事故排放影响分析污水处理厂废水事故排放可认为是由于设备事故或能源事故，使污水未经处理直接排放，以CODcr 和BOD5作为预测因子进行预测，则出水水质为CODcr：880mg/L，BOD5：530mg/L，以角干为预测断面，预测结果见表7。
表7 废水事故排放影响预测单位：mg/L到地表水水质标准。
因此，若污水处理厂废水处理设备发生故障，应排入污水事故储池，经处理后再排放。
4.2大气污染事故影响预测（1）预测模式采用非正常排放模式进行预测，预测模式为：式中：t为扩散时间；T为非正常排放时间。
（2）燃煤烟气事故排放影响分析主要预测事故状况下的影响和超标范围,详见表8。
根据以上计算结果表明，废气处理设备发生故障导致事故排放时，各污染物对周围环境的影响较正常排放时影响严重很多，建设项目周围居民点在超标范围内，会受到一定的影响，但事故排放持续时间在20min左右，事故排放发生30min后，环境质量可恢复达标水平，事故影响在可以接受的范围之内。
但建设单位须加强防止事故发生的措施。
4.3火灾爆炸事故影响分析（1）火灾爆炸分析本项目火灾事故主要为氯酸钠发生火灾事故。
火灾事故的燃烧半径D和持续时间T可由下面公式计算：D(m)=2.66M0.327T(S)=1.098M0.327式中：M为燃烧物质的质量（Kg）。
该项目污水设计加氯量为8mg/l，再生水加氯量为14mg/l，当生产1g有效率要消耗氯酸钠0.65g，则日处理11万t污水和3万t 中水，每日共需氯酸钠941.6kg。
该项目原料的储存周期小于10天，则氯酸钠的储量最大为10t。
目前，对于辨识化学危险源的化学物质阈限量国内还没有统一的标准。
1982年6月欧共体颁布了《工业活动中重大事故危险法令》，该法令列出180种物质及其临界量标准。
如果工厂内某一设施或互相关联的一群设施中聚集了超过临界量的危险物质，则将这一设施或这一群设施定义为一个重大危险源。
OECD该法令对于氯酸钠的限量为250t。
所以本项目氯酸钠的储量远小于该临界量，不属于重大危险源。
经计算，其燃烧半径分别为54.06m，燃烧时间分别为22.3秒。
爆炸是突发性的能量释放，造成大气中破坏性的冲击波、爆炸碎片等形成抛射物，造成危害。
发生火灾时，火场的温度很高，辐射热强烈。
且火灾蔓延速度较快，如果不及时抢救，极易造成大面积火灾。
火灾、爆炸事故对环境的危害是热辐射、冲击波和抛射物造成的后果。
此外，火灾燃烧过程产生的烟雾和有害气体可造成较大范围的环境污染。
根据上述计算，火灾燃烧的最大范围为54.06m，因此，发生火灾时，如果不引发周围的物品燃烧，则仅限于库房范围内，所以在氯酸钠库房范围内，不要堆放易燃、易爆的物品。
（2）水体污染后果评述当发生火灾时，为迅速控制火势，消防设施用水进行灭火，将产生消防废水。
根据消防用水量按15l/s计算,发生火灾时消防用水量约为335m3，根据类比调查分析，消防废水产生量约为用水量的90%，因此本项目消防废水产生量为300t。
即使不经过收集与处理，也基本上可将消防废水滞留在厂区内，待火灾过后，经自然蒸发即可消除，所以消防废水不会对外环境产生影响。
4.4事故影响评价（1）大气事故影响评价由以上分析结果可见，本项目发生的废气处理事故虽较正常排放情况下影响严重，但在短时间内可以得到有效的控制，但也应采取有效的预防和应急措施，最大程度减少事故发生的概率。
（2）污水处理厂事故影响分析污水处理厂出现事故，按最不利因素计算，废水直接排入水渠。
本项目废水主要特征污染为CODcr ，废水中CODcr浓度为880mg/l, 严重超过排放标准，会引起地表水环境的恶化，所以应加强防范，尽可能杜绝事故的发生。
（3）火灾爆炸事故影响分析该项目的氯酸钠储量较小，一旦发生火灾，其影响面积可控制在厂区范围之内。
由于该化学品本身不能自燃，所以应严格杜绝该物品与有机物、金属粉末、浓硫酸、盐酸、及其它还原性物质等共同贮存。
5事故的预防措施及应急计划我国在安全生产上一贯坚持“安全第一、预防为主”的方针，工作重点应放在预防上。
在事故救援上实行“企业自救为主、社会救援为辅”的原则。
事故的应急计划是根据工程风险源风险分析，制定的防止事故发生和减少事故发生的损失的计划。
因此制定本项目的事故应急计划是十分必要的。
5.1对化学药品的风险事故管理（1）对化学物品的管理与使用●根据国家《建筑设计防火规范》GBJ16-87，按生产的火灾危险性分类，氯酸钠属甲类产品，该规范规定氯酸钠在厂房或实验内的最大允许量为50kg，每平方米房间体积最大允许量为0.015kg/m3。
所以在生产过程中，应按此规范进行操作，在二氧化氯发生间内的氯酸钠存放量要始终小于该规范规定的允许量。
●应严格执行国家《危险化学品安全管理条例》（第344号令）的规定。
根据国家有关规定，化学性质相互抵触的化学危险品不能存放在同一房间内。
所以强氧化剂氯酸钠不得用有机物包装，不得与有机物以及盐酸储存在同一库房内，以防造成事故隐患。
●凡有毒及腐蚀性的化学物品，必须建立严格的发放贮存制度，要有专人管理，贮存量有一定限度。
●在使用氯酸钠、盐酸等腐蚀性物质时，为防止灼伤人体，操作时必须穿戴好防护用品，并严格按操作规程操作。
（2）成立应急救援组织机构并有明确的职责划分●应急救援组织机构应由公司主要负责人担任总指挥，并由责任心强、熟悉化学药品特性的人员为组织机构成员。
●制定应急预案，定期组织公司管理人员、药品管理员、运送人员进行预案演练，发生事故时，应立即利用自身力量进行现场抢救，并向本企业领导报告。
●根据灾情向有关部门报警（消防119、救护120、交通事故122、治安110），并向上级主管部门报告。
发生易燃、易爆物品事故要在周边50m危险距离内进行及时疏散及清理，对负伤人员及时送就近医院抢救或等待120救护车到来。
●报警、通讯联络方式采取手机（电话）报警联络方式，公司并保持值班电话24小时通讯联络的畅通。
（3）预案的启动运送、使用、管理危险物品过程中应当严格遵守企业安全生产操作规程，相关人员必须切实掌握所运物品的特性和应急措施，一旦发生事故时，立即启动应急预案。
（4）事故发生后应采取的紧急处理措施●发生事故后，相关人员应根据化学药品的性质，采取相应的急救措施，防止事故损失扩大，并立即进入临战状态。