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Legionella risk assessor Jacqui Goss explains why all dental practices need their water systems checked regularly

First let me clear up any misunderstandings – Legionella Risk Assessments (LRAs) were not invented

for dental practices by the CQC and dentists are not being singled out. It is the Health and Safety at Work etc Act 1974 (HSWA) and the Control of Substances Hazardous to Health Regulations 1999 (COSHH) which are concerned with the risk from exposure to legionella bacteria. Guidance on how to comply with the legislation comes in the form of a document published by the Health and Safety Executive entitled Legionnaires’ disease, The control of legionella bacteria in water systems Approved Code of Practice and guidance.

To comply with their legal duties, employers and those with responsibilities for the control of premises should:(a) identify and assess sources of risk;(b) prepare a scheme for preventing or controlling the risk;(c) implement, manage and monitor precautions;(d) keep records of the precautions; and(e) appoint a person to be managerially responsible.

(I’ve abbreviated what it says in the HSE leaflet).

In addition, DH Health Technical Memorandum 04-01: The control of

Legionella, hygiene, ‘safe’ hot water, cold water and drinking systems applies to dental practices and for CQC compliance you must meet relevant health and safety legislation.

Under the legislation, dental practices must carry out, or engage someone to carry out on their behalf, an LRA at least every two years. An LRA should also be carried out if there have been, for example, changes to the water system or changes to the use of the building. The person undertaking the LRA must be competent to do so – which effectively means successfully completing a course and examination on the subject.

What is or are Legionella?Legionella bacteria can cause a range of diseases called Legionellosis. The best

known is Legionnaires’ disease because it is a potentially fatal form of pneumonia. Certain groups of people are more susceptible to catching the disease. They are:• The very young• People over 45• Immuno-comprised people• Smokers• Alcoholics• Men more than women.

Legionella bacteria are present in most natural sources of water and survive at temperatures between 6°C and 60°C. They are dormant below 20°C but multiply at temperatures between 20°C and 45°C. Crucially, the optimum temperature range for the proliferation of Legionella bacteria is 36°C to 37°C. However, to multiply

practicemanagement

What is a Legionella Risk Assessment all about?

With a degree in chemistry and as a qualified and highly experienced Legionella risk assessor, Jacqui Goss was recently head hunted by City Water Limited based on her

easy-to-understand but comprehensive LRA reports.

Figure 1: Jacqui in action conducting an LRA. ‘As I clamber into yet another dark, dusty loft or dank basement in search of a water tank, I often wonder what new forms of life I’ll discover!’

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Legionella bacteria need nutrients – such as algae, amoebae, sediment, sludge, scale, corrosion by-products, biofilms and other bacteria.

The sort of systems most at risk of harbouring harmful Legionella bacteria are:• Water systems involving a cooling tower or evaporative condenser• Air-conditioning systems, especially those incorporating humidifiers or air-washers• Hot and cold water systems• Spa baths, whirlpool bathtubs and other pools in which water is agitated and re-circulated• Other systems where water is stored between the temperatures of 20-45°C • Any system that produces an aerosol or spray during operation or when being maintained.

Note that anywhere where water is stored or used between the temperatures of 20°C and 45°C, in the presence of nutrients, is a potential breeding ground for Legionella bacteria. Also, where infected water is formed into a spray or mist, the risk of inhalation and infection is significant.

What is an LRA?Essentially, a Legionella Risk Assessment is a thorough examination of the hot and cold water systems in a business premises by a qualified assessor. She or he inspects and tests the water systems to assess the potential risk of an outbreak of Legionnaires’ disease or other diseases caused by Legionella bacteria.

So, for example, potential hazards could include:• Cold water storage rising above 20°C• Hot water storage temperatures below 60°C• Hot water circulation temperatures below 50°C• So-called ‘dead-legs’ in pipework (a water pipe that is blocked off and so may well contain stagnant water which can then back contaminate into the rest of the system)• Partially blocked shower heads resulting in increased microbiological activity• Systems or parts of system unused for seven days or more• Poor maintenance or lack of regular servicing.

How is an LRA conducted?Depending on the size of the premises and the complexity of the water system, an LRA can take a few hours or (in the case of

some multi-surgery general practices I have visited) over nine hours. The assessor must examine the entire water system and take temperature readings at water outlets. As I clamber into yet another dark, dusty loft or descend into a dank basement in search of a water tank, I often wonder what new forms of life I’ll discover!

In addition to the potential hazards mentioned above, I will be looking to see if appropriate Legionella bacteria control measures are in place. These could include:• Controlling the release of water spray• The use of water treatments in dental unit waterlines (DUWLs)• Hot water hot enough and cold water cold enough to prevent or minimise Legionella bacteria growth• Recirculating hot water systems (unless the system is very small)• Water tanks covered with a close-fitting lid• Insulated pipes.

What happens next?At the end of a LRA, the person responsible for the premises and/or the person nominated with managerial responsibility is sent a comprehensive report. And I do mean comprehensive. It will include a Water Schematic Drawing (a diagrammatic representation of the whole water system), a compliant Written Scheme and Water Log Sheets. This report could run to 60 pages or more and is both important and highly useful to the dental practice. As well as providing background information on Legionella, it details the management responsibilities and sources of guidance. Safe and correct operating standards are covered for all water system components and there is considerable detail on control measures, including a temperature monitoring schedule and a maintenance inspection schedule of checks. Areas of risk are listed, together with information about record keeping. The document explains what to do in the event of an outbreak of Legionellosis and some may provide a very handy glossary of terms.

Is it all worth it?Sceptics argue that no dental patient has ever died of Legionnaires’ disease but this is not so. In February last year, The Lancet reported on the case of an Italian woman who died of Legionnaires’ disease – the cause being traced to L. penumophila bacteria in tap and dental unit waterlines.

LRAs by professional assessors need not

Figure 2: An example of water tank contamination in a dental practice

be expensive and ongoing monitoring, if too time consuming, can be done with outside help. To quote the trademark of a well-known sports shoes manufacturer, Just Do It.Care to comment? @AesDenToday

Figure 3: Limescale and biofilm provide nutrients for the proliferation of Legionella bacteria

Figures 4-5: So-called ‘dead legs’ are a potential source of stagnant water and can back contaminate into the rest of the water system