1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsWB9423_BSI_StandardColCov_noK_AW:BSI FRONT COVERS 5/9/08 12:55 Page 1Sampling for Legionella bacteria in water systems Code of practiceBS 7592:2008BS 7592:2008 BritiSh StandardPublis
2、hing and copyright informationthe BSi copyright notice displayed in this document indicates when the document was last issued. BSi 2008iSBn 978 0 580 58282 0iCS 07.100.20the following BSi references relate to the work on this standard: Committee reference Eh/3/4 draft for comment 08/30161147 dCPubli
3、cation historyFirst published november 1992 First revision 30th november 2008Amendments issued since publicationAmd. No. Date Text affected BritiSh Standard BSI 2008 iBS 7592:2008Summary of pagesthis document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 36, an inside bac
4、k cover and a back cover.ContentsForeword iiiintroduction 1Section 1: General 31 Scope 32 normative references 33 terms and definitions 34 risk assessments 65 Safety of sampling personnel 76 Survey and sampling 87 apparatus and materials 10Section 2: Routine sampling 138 Sampling procedures 139 Samp
5、le transport and storage 25Section 3: Sampling for outbreak and other investigations 2710 General 2711 Safety of sampling personnel 2812 apparatus and materials 2813 Sampling procedures 2814 Other sources 32Annexesannex a (informative) Label and sample collection form information 33Bibliography 34BS
6、 7592:2008 BritiSh StandardThis page deliberately left blankBritiSh Standard BSI 2008 iiiBS 7592:2008ForewordPublishing informationthis British Standard is published by BSi and came into effect on 30 november 2008. it was prepared by Subcommittee Eh/3/4, Microbiological methods, under the authority
7、of technical Committee Eh/3, Water quality. a list of organizations represented on this committee can be obtained on request to its secretary.Supersessionthis British Standard supersedes BS 7592:1992, which is withdrawn.Information about this documentthis is a full revision of the standard, and intr
8、oduces the following principal changes:this document makes a clearer distinction between routine and incident sampling.it provides a clearer rationale for routine sampling, including newly-recognised sources, risk assessment, surveying and sample points.it revises acceptable transport times to accou
9、nt for more quantative results and sampling/transport subcontracting. it takes account of new standards documents for water sampling and analysis.Hazard warningsWARNING. this British Standard calls for the use of substances and/or procedures that can be injurious to health if adequate precautions ar
10、e not taken. it refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stageUse of this documentas a code of practice, this British Standard takes the form of guidance and recommendations. it should not be quoted as if it were a
11、 specification and particular care should be taken to ensure that claims of compliance are not misleading.any user claiming compliance with this British Standard is expected to be able to justify any course of action that deviates from its recommendations.it has been assumed in the preparation of th
12、is British Standard that the execution of its provisions will be entrusted to appropriately qualified and experienced people, for whose use it has been produced.Presentational conventionsthe provisions in this standard are presented in roman (i.e. upright) type. its recommendations are expressed in
13、sentences in which the principal auxiliary verb is “should”.BS 7592:2008iv BSI 2008BritiSh StandardCommentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.Contractual and legal considerationsthis publication does not p
14、urport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.in particular attention is drawn to the following statutory regulations:the health and Safety at Work etc.
15、act 1974 1.the Management of health and Safety at Work regulations 1999 2.the Control of Substances hazardous to health regulations 2002 (as amended) 3.BritiSh Standard BSI 2008 1BS 7592:2008IntroductionLegionnaires disease was first recognised in July 1976 and the bacterium later isolated and named
16、 Legionella pneumophila. Since then, over 50 other species of Legionella have been described of which at least 20 have been associated with disease in humans. these organisms are widespread in the natural aquatic environment and in artificial water systems. the organism is an opportunistic human pat
17、hogen and infection is more often associated with artificial water systems. the disease is not known to be transmissible via person-to-person contact. as a result, the way to prevent or control outbreaks of Legionnaires disease is to inhibit or limit the growth of these organisms in water. in the UK
18、, the control of legionellae (bacteria of the genus Legionella) falls within the general requirements of the health and Safety at Work etc. act 1 and the Control of Substances hazardous to health regulations 2002 (as amended) 3.Legionellae are only able to grow in water in the presence of other micr
19、oorganisms. in vitro they have been shown to be capable of growth within a number of protozoa, particularly amoebae and to be supported by some bacteria such as flavobacteria. in addition, legionellae have been shown to be associated with biofilm on surfaces in water systems where they can grow in t
20、he protozoa grazing the biofilm and there is also evidence suggesting they can grow outside protozoa alongside and supported by other organisms within the biofilm. Growth within protozoa, particularly with the potential for incorporation within protozoal cysts, can protect legionellae from biocides,
21、 heat and drying. this enables the legionellae to survive under conditions that would otherwise be fatal to them and to be transported within both protozoa and cysts to more favourable environments where they might subsequently grow. the association with biofilms, as with other aquatic bacteria, off
22、ers legionellae a nutritional advantage and also provides them with some protection against adverse environmental conditions, particularly biocides, that would otherwise kill them if they were simply suspended within the water column. thus control of biofilm formation within water systems is of para
23、mount importance for the control of legionellae. the numbers of reports of Legionnaires disease continues to rise, probably due to an increased recognition of the disease using improved diagnostic methods but possibly also resulting from a greater exposure to potential sources. to demonstrate that m
24、easures to control legionellae are effective there is an increasing need to sample potential sources for the presence of legionellae. Sampling is also required when investigating the sources of infection in cases of Legionnaires disease. it is, therefore, the aim of this document to bring together i
25、nformation on likely sources of Legionnaires disease, the selection of sampling sites and the methods of sampling for the purposes of routine monitoring, investigating a problem, or an outbreak investigation. although it is necessary to cover some aspects of risk assessment in order to facilitate th
26、e selection of sampling sites, it is not the intention to give extensive explanations of how to carry out a risk assessment, as this is covered elsewhere, for example, in the Water Management Society guide 4. to ensure personnel safety, a risk assessment of the system to be sampled should be conduct
27、ed before sampling.in the UK, outbreaks of Legionnaires disease have been commonly associated with evaporative cooling towers and condensers, hot and BS 7592:20082 BSI 2008BritiSh Standardcold water systems in large buildings, such as hospitals and hotels, and spa pools. the use of nebulizers, or ot
28、her medical respiratory equipment, contaminated with legionellae (usually by filling or washing such items with tap water containing the bacteria) has also been reported to cause infection. Other sources that have been implicated in outbreaks globally include cutting fluids (containing oil-in-water
29、emulsions of about 95% water, and used for lubricating machine tools), natural warm spas or hot springs, indoor fountains, potting composts and ultrasonic misting devices used to humidify food display areas in shops and restaurants, pressure washers, air scrubbers and effluent treatment plants. hous
30、ehold plumbing systems have also been implicated as sources of Legionnaires disease. in one UK study 5, legionellae were isolated from approximately 15% of the homes of patients compared with approximately 5% of homes used for control purposes.BritiSh Standard BSI 2008 3BS 7592:2008Section 1: Genera
31、l1 Scopethis British Standard gives recommendations and guidance on the sampling of water and related materials for determination of the presence of organisms of the genus Legionella. it is applicable to sampling artificial water systems and also gives methods for sampling of biofilms and sediments
32、that might be present in water systems. Some of the same sampling principles can be applied to natural water systems.the standard is applicable to both sampling for routine monitoring and in outbreak investigations. For the latter, recommendations and guidance on the selection of sampling points are
33、 given. the rationale for the selection of sampling points for particular situations is also discussed.this British Standard is intended for use by all those involved in water sampling for legionellae including the persons taking samples on site and their employers.2 Normative referencesBS En iSO 19
34、458, Water quality Sampling for microbiological analysis3 Terms and definitionsFor the purposes of this British Standard, the following terms and definitions apply.3.1 aerosolsuspension in a gaseous medium of solid particles, liquid particles or solid and liquid particles having negligible falling v
35、elocity3.2 artificial water systemwater system that has been constructed and does not occur naturally, e.g. a hot water system3.3 biocide substance which kills micro-organisms3.4 biofilm community of bacteria and other micro-organisms, embedded in a protective layer with entrained debris, attached t
36、o a surface3.5 blindendlength of pipe closed at one end through which no water can pass3.6 calorifierapparatus used for the transfer of heat to water in a vessel by indirect means, the source of heat being contained within a pipe or coil immersed in the waterNOTE 1 see also plate heat exchanger (3.2
37、1).NOTE 2 A storage calorifier also stores some of the heated water in the same vessel.BS 7592:20084 BSI 2008BritiSh Standard3.7 cold water systeminstallation of plant, pipes and fittings in which cold water is stored, distributed and subsequently discharged3.8 cooling towerdevice for cooling water
38、that, in turn, is used for cooling in a processNOTE The water is passed over the tower against an air stream. Water evaporates which causes the water to be cooled. The cooler water is then usually pumped to a heat exchanger to be reheated and recycled through the tower.3.9 cisterntank for storage of
39、 waterNOTE This includes all cisterns, not just WC cisterns.3.10 deadleglength of pipe leading (to a fitting) through which water only passes when the fitting is operated3.11 distribution systempipework which distributes water from hot/cold/cooling water plant to one or more fittings/appliances/proc
40、esses3.12 domestic water supply hot and cold water intended for personal hygiene, culinary, drinking water or other domestic purposes NOTE This applies to all such systems and not just those in dwellings.3.13 evaporative condenserdevice similar to a cooling tower, water is passed through the tower a
41、gainst an air stream but, as the water falls, it also passes over a heat exchanger within the body of the tower; the heat exchanger contains a refrigerant gas that is condensed by the cooling effect of the water passing over it3.14 evaporative coolingprocess by which a small portion of circulating w
42、ater is caused to evaporate, thereby taking the required latent heat of vaporization from the remainder of the water and causing it to cool3.15 hot water systeminstallation of plant, pipes and fittings in which water is heated, distributed and subsequently discharged (not including cold water feed c
43、istern or cistern)3.16 legionellosisany illness caused by exposure to legionellae3.17 Legionnaires diseaseform of pneumonia caused by legionellaeBritiSh Standard BSI 2008 5BS 7592:20083.18 pontiac feverupper respiratory illness caused by legionellae, but less severe than Legionnaires disease3.19 non
44、oxidizing biocidebiocide that functions by mechanisms other than oxidation, including interference with cell metabolism and structure3.20 oxidizing biocidesubstance capable of oxidizing organic matter, for example cell material, enzymes or proteins that are associated with microbiological population
45、s resulting in death of the micro-organismsNOTE The most commonly used oxidizing biocides are based on chlorine or bromine (halogens) that liberate hypochlorous or hypobromous acids respectively on hydrolysis in water. The exception is chlorine dioxide, which does not hydrolyse but exists as a solut
46、ion. However, chlorine dioxide functions in the same way as other oxidizing biocides.3.21 plate heat exchanger type of heat exchanger that uses metal plates to indirectly transfer heat between hot and cold waterNOTE Often used in conjunction with a hot water storage vessel.3.22 legionella risk asses
47、smentidentifying and assessing the risk from legionellosis from work activities and water sources on premises, and determining any necessary precautionary measures3.23 sentinel tapshot water services the first and last taps on a re-circulating system; cold water systems (or non-re-circulating hot wa
48、ter system) the nearest and furthest taps from the storage cistern (water heater) NOTE The choice of sentinel taps might include other taps which are considered to represent a particular risk, for example, the coolest part of a hot water system or the warmest part of a cold water system.3.24 spa poo
49、lself-contained body of warm water designed for sitting in (not whole body immersion), intended for a small number of people to use at one time; the water is re-circulated and kept between 30 40C and is usually not drained between use and is continually filtered and cleaned; hydro-jet circulation, with or without an air induction bubble system, is also used to agitate the waterNOTE Spa pools are known under a range of names spa bath, hot spa, hot tub, portable spa, whirlpool spa, swim spa and often JacuzzitM. All systems us
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