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Issues Associated with the Decontamination of Laundry and Clinical Waste

Peter HoffmanLaboratory of Healthcare-associated Infection, Health Protection Agency, London, UK

19.4

Introduction

This chapter deals with two areas with contrasting legislative cov-erage in the UK. The first section, healthcare laundry, has no specific legislative basis and is covered by more general legislation, primarily the Health and Safety at Work etc. Act (HSAWA) and the Control of Substances Hazardous to Health Regulations (COSHH). The second, the clinical waste component of health-care waste, has a specific, substantial and varied legislative basis within the component nations of the UK covering the classifica-tion, transport and disposal of trades waste and hazardous sub-stances, with healthcare waste being only one of many waste categories covered, as well as the HSAWA and COSHH. The UK approach is based on interpretations of regulations that apply throughout the European Union. This contrasts with the USA, where there are generally no federal regulations on medical waste generation, transport and disposal, and individual state regula-tions apply but there is a federal requirement for “cradle-to-grave” tracking of medical waste.

Healthcare laundry

The washing of fabrics is probably the largest, by weight, decon-tamination task in the healthcare sector, yet it remains the one with the least clinical input or appreciation of its components. As

with many other preventative interventions, it is not possible to gauge precisely the value of effective healthcare laundry decon-tamination, but bacteria causing infections in patients have been found on their bedsheets [1]. Contact between patients and their bedding is close and prolonged, and should bedding not be decontaminated between successive uses, there is a clear and sig-nificant potential for such fabrics to act as a vector of infection. In the UK, healthcare linens tend to be supplied by laundries that serve several hospitals rather than being owned by an individual hospital. This increases the potential for interhospital transmis-sion of microbial strains causing healthcare-associated infections should laundry decontamination fail. Such transmission is most significant if it is with microbes that are already adapted to spreading and causing problematic infections in healthcare, such as those involving bacteria resistant to multiple antibiotics.

Routine healthcare laundryThe laundering of fabrics can combine two factors that reduce microbial contamination: there is always dilution (inherent in the washing process) and there can also be additional disinfec-tion (thermal and/or chemical). Ironically, commercial laundries use as little water, and thus dilution, as possible. It represents a major cost in buying it and disposing of it to a public sewer (both charged by volume); the more water is used, the more it costs to heat it to the right temperature and the more it costs in process chemicals (detergents, etc.) to attain the correct concen-trations. So large-scale commercial laundries favor automated

Russell, Hugo & Ayliffe’s: Principles and Practice of Disinfection, Preservation and Sterilization, Fifth Edition. Edited by Adam P. Fraise, Jean-Yves Maillard,

and Syed A. Sattar.

© 2013 Blackwell Publishing Ltd. Published 2013 by Blackwell Publishing Ltd.

Introduction, 471Healthcare laundry, 471Clinical waste, 474

Conclusions, 476References, 476Further reading, 477

Special Problems in Hospital Environments19

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Figure 19.4.3 Linen processed by a tunnel washer.

to each other. Heat and wash chemicals can be added to indi-vidual compartments.

After clean linen is ejected from the last compartment (Figure 19.4.3), in the majority of laundries it proceeds automatically via a conveyer belt to a tumble drier set at a temperature and time appropriate to a particular linen type, for example sheets requir-ing less drying than towels. This dividing of linens into separate drying types for each load, essential for the economics of the process, requires laundry to be sorted before it is loaded into the CTWM. Such sorting is by hand, and the industrial conditions and high linen volumes mean that personal protective equipment used by staff is unlikely to be as effective as it would be when used by healthcare staff in clinical situations. Thus, safety requirements normally necessitate that linens contaminated with highly infec-tious microbes should not be processed by CTWMs.

Washer extractorsThese are similar to large domestic or launderette washing machines where successive volumes of water and wash chemicals are added to linen in the wash compartment (Figure 19.4.4). These use high volumes of water and take about 40–50 min to process a single load (as opposed to a CTWM producing a load of clean linen every 2 min), making them highly uneconomic for processing anything but a very small proportion of laundry. They do have the advantage that a load of linen can be added with minimal staff contact, making them a much safer option for loads contaminated with highly infectious microbes.

Categorization of healthcare laundryFor the safety of laundry workers, linens contaminated with highly infectious microbes need to be clearly identifiable so that they can be loaded with minimal handling into washer extractors, rather than be hand-sorted for processing via a CTWM. The concept of “universal precautions” (treating all linens as infec-tious and processing them with minimal handling via washer extractors) has no place in healthcare laundries as there is too little washer-extractor capacity and it would be vastly uneco-nomic to process all linens this way. Microbiological safety in

washing processes that have a high throughput and use low water volumes; this is exemplified in continuous tunnel washing machines.

Continuous tunnel washing machinesContinuous tunnel washing machines (CTWMs), also known as batch continuous washing machines or, more usually, tunnel washers, process the vast majority of healthcare laundry (Figure 19.4.1). A CTWM comprises a large metal cylinder (Figure 19.4.2), about 2 m in diameter and 15 m in length with an inter-nal Archimedean screw that effectively divides it into a number of compartments, each of which contains one load of linen. This cylinder is on rollers, and rocks back and forth, agitating the linen in each compartment then, about every 2 min, the cylinder rotates 360°, moving each load of linen on to the next compart-ment. At the same time, another load of soiled laundry is added to the first compartment and a load of clean linen is ejected from the last compartment. Clean water is added to the last compart-ment and flows, either by gravity through small holes in the Archimedean screw or via pumps, backwards through the cylin-der so, in essence, clean water and dirty linen flow countercurrent

Figure 19.4.1 Example of a tunnel washer.

Figure 19.4.2 Detail of metal cylinder in a tunnel washer.

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Chapter 19.4 Issues Associated with the Decontamination of Laundry and Clinical Waste

laundry from acute healthcare and is predominantly patients’ own clothing in long-stay facilities.

Decontamination of laundryBoth “used” and “infectious” linen should be heat disinfected using a minimum of either 65°C for 10 min or 71°C for 3 min [2]. These holding times apply only from when the linen has equili-brated to the disinfection temperature. There is no difference in the decontamination parameters between these two categories, only in the handling before decontamination. Used linen is usually sorted into different drying types and is processed in a CTWM; infectious linen is usually loaded directly into a washer extractor with minimal handling.

Thermolabile linen is processed in a washer extractor at sub-disinfection temperatures and chemically disinfected with sodium hypochlorite at 150 ppm available chlorine and a contact time of at least 5 min in the penultimate rinse. This disinfection must be in a rinse phase as any organic matter present before washing could inactivate the low hypochlorite concentration needed to keep bleaching to a minimum. It is in the penultimate rinse, so that the last rinse can remove the odor of chlorine from the fabric. Some other chemical disinfection processes, such as the dosing of wash and rinsewater with ozone, may also be suitable for use in washer extractors if continuously monitored.

Chemical disinfection of used and infectious laundryThis remains largely unexplored on an industrial scale but the energy savings that could be made by using chemical disinfec-tion at more modestly elevated temperatures are attractive. If this is to be used, disinfectants need to be shown to have suffi-cient activity at the concentration, exposure time and tempera-ture that are achieved in practice. Laboratory data showing activity outside these parameters offers no indication of prac-tical efficacy. Following laboratory tests, there would need to be verification that, with specified cycle parameters, effective disinfection can occur in the actual wash process used. That these parameters are being achieved in every wash should also be part of the quality assurance of the routine process and these parameters should be observable in real time rather than in retrospect.

Staff uniformsThe laundering of healthcare staff uniforms is a controversial and sometimes emotive area. This was examined in a review of available evidence and informed opinion [3], and guidance based on this was issued by the English Department of Health [4] which suggests that there is little hygienic difference between domestic and commercial washing of uniforms, even at lower wash temperatures. The uniforms of clinical staff can be washed in their own domestic washing machines as part of a mixed load at temperatures appropriate for that fabric type. If uniforms are heavily soiled, they should be washed domestically separately from other items or can be sent for commercial healthcare laundering.

laundries is achieved by standard precautions (such as personal protective equipment, handwashing before eating or drinking, etc.) by those sorting linen for CTWM processing and additional precautions (minimal contact) by those loading linen contami-nated with highly infectious microbes into washer extractors. This requires categorization of laundry into the two main types (“used” and “infectious” – see below) at the point of production by those aware of an individual patient’s status.• Used linen. This is the vast majority of healthcare linens. It can be soiled or contaminated with blood, feces or other body fluids (“fouled”). It can be from patients with infections that are not readily transmitted to laundry workers (e.g. the presence of methicillin-resistant Staphylococcus aureus (MRSA) or Clostrid-ium difficile is acceptable on used linen).• Infectious linen. This is linen contaminated with microbes that are an infectious hazard to those who may come into contact with it. These should be defined locally but could include microbes readily transmitted by the fecal–oral route (Salmonella, Shigella, norovirus, etc.) and linens bloodstained from known or suspected bloodborne virus carriers. This type of linen is some-times misleadingly referred to as “infected”, a term that encour-ages clinical staff to use this classification for linen from a patient with any infection, the vast majority of which pose a minimal hazard to those coming into contact with it.• Thermolabile linen. This is linen that would be damaged by heat disinfection. It should form a very small proportion of

Figure 19.4.4 Washer extractor.

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Clinical waste

The classification, transport and disposal of clinical waste are governed by a stronger legislative base than most other areas of healthcare that involve decontamination and infection preven-tion. Essentially, waste from healthcare is classified as a category of industrial waste, different components of which may contain a wide variety of hazards, for example harmful, toxic, mutagenic, flammable and infectious. Wastes may also contain more than one hazard. Although this section will only cover those wastes classified under the Hazardous Waste Regulations as category H9 “infectious”, healthcare establishments have an overall duty to meet legislative requirements for all types of waste that they produce, both for safety and environmental reasons. For example, the Health and Social Care Act 2008 Code of Practice on the prevention and control of infections and related guidance [7] requires that “The risks from waste disposal should be properly controlled” and “Systems should be in place to ensure that the risks to service users from exposure to infections caused by waste present in the environment are properly managed, and that duties under environmental law are discharged”. Guidance on how to achieve this is given in the Department of Health’s document Safe Management of Healthcare Waste [8]. The Code of Practice covers “registered providers of all healthcare and adult social care in England” – that is not just hospitals, but general medical practi-tioners, dentists, podiatrists, opticians, pharmacies, private and independent healthcare organizations, ambulance trusts, comple-mentary and alternative treatments, residential homes and similar establishments.

Healthcare waste is defined as being waste specifically associ-ated with the activity of healthcare. Wastes incidental to the activity of healthcare (examples would be waste oil from an ambulance or food waste from a hospital kitchen) are not healthcare waste.

Segregation of clinical wasteIt is a legal requirement that items of healthcare waste be classified according to the risk or risks they possess such they can be trans-ported and disposed of appropriately. With regard to infectious waste, it can be either category A or B:• Category A infectious waste is: “an infectious substance which is transported in a form that, when exposure to it occurs, is capable of causing permanent disability, life-threatening or fatal disease to humans or animals”.• Category B infectious waste is: “an infectious substance which does not meet the criteria for inclusion in Category A”.The interpretation of category A waste is that from patients with viral hemorrhagic fevers, monkeypox virus and variola, and cul-tures of containment level 3 microorganisms. This means that all routine infectious clinical waste is category B.

In addition to the attribute “infectious”, other hazards must be considered in the classification of infectious waste for transport and disposal. The main additional hazard classifications are:

Dry cleaningThere should be minimal need for dry cleaning of healthcare fabrics but it may occasionally be needed for patients’ personal clothing or particularly treasured soft toys. While there is a little evidence that the process gives some reduction in enveloped viruses and some bacteria [5], for those microbes not killed by the solvent used there can be poor reduction produced by the dilution of the wash process alone. Where steam pressing can be used to finish garments, this will add a heat disinfection element. Dry cleaning should not be an infection control measure of first choice.

Washing machines in acute clinical areasThese should be generally discouraged, but there may be a few areas where their use is difficult to avoid. For example, some neonatal units may have small woolen items such as babies’ socks that are unsuitable for industrial washing. If such units are for-bidden washing machines, these items may only be rinsed out and dried on radiators between uses. If this is the case, the instal-lation of washing machines and driers on a planned preventative maintenance schedule and agreements about what they can pro-cess, may represent acceptable risk control. There should also be an understanding that, in case of infection outbreaks, special measures in agreement with the local infection control team, such as treating delicate clothing items as single use, may be necessary.

Laundry quality assurance systemsThe most common quality assurance system for laundries is based on the standard EN14065 Textiles. Laundry Processed Tex-tiles. Biocontamination Control System [6]. This is similar to other hazard analysis critical control point (HACCP) systems but in this context is known as a risk analysis biocontamination control (RABC) system. In this system, representatives of the laundry and invited advisors decide what local parameters are important to the production of microbiologically acceptable textiles, how to measure them, what values are acceptable, the tolerances on those values and corrective actions when those values are exceeded. In practice, this system is reliable only if the team devising and implementing it are knowledgeable about what the critical parameters really are. It is possible to have RABC systems where irrelevant surfaces are sampled (the hoppers that contain fabrics pre-decontamination, for example) and pointless corrective actions taken. If appraising an RABC system, the most important steps are the decontamination parameters (usually monitoring of the temperature of disinfection and the duration it is maintained) and prevention of recontamination with healthcare-associated contamination (i.e. directly or indirectly from undecontaminated linen), both at the laundry and during transport (the same vehicle is usually used for collection of dirty linen and the delivery of clean linen).

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Offensive wasteThis is healthcare waste that does not have the hazardous proper-ties of clinical waste but may cause offense. Examples being incontinence pads, nappies and sanitary waste from healthcare. Offensive waste should be collected in yellow bags with promi-nent black stripes (“tiger stripe” bags). This waste can go to land-fill sites licensed for this type of waste or be incinerated at municipal (i.e. not clinical waste) incinerators such as energy-from-waste facilities; such final disposal is significantly less ex -pensive than either clinical waste incineration or alternative treatments. This is a substantially underused healthcare waste category and if a higher proportion of offensive waste were clas-sified as such, it would represent a substantial cost and energy saving in healthcare waste disposal.

The risk assessment for waste being offensive rather than infec-tious can be done on a generic basis, for example incontinence pads from units where these are in routine use and are not associ-ated with infectious conditions could generically be considered as offensive waste. This would change if there were clinical suspicion of the presence of infection, for example if there were a norovirus outbreak.

Storage of clinical wasteBulk waste should be stored before collection in an enclosed, secure, cleanable area that can be locked when access in not required. There should be segregation of different waste types within this area. It should have washing facilities for staff.

Transfer documentationBulk wastes must have documentation that accurately describes the waste and its origins. This documentation (a “waste transfer note”) must follow the waste from its origin to the point of final disposal. Small amounts of waste, for example that carried in an individual ambulance or produced by a GP practice, do not require such documentation, but when that waste is collected into a bulk quantity, documentation is required.

Accidents and incidentsWithin any waste management policy should be actions to be taken in case of spillage. Staff should be trained in how to deal with spills of infectious waste, including sharps. Suitable spill kits and disinfectants should be provided.

Final disposal methodFinal disposal by incineration was traditionally the fate of all infectious clinical waste. A variety of constraints, principally stringent pollution controls, make this an expensive option and likely to become more so. It is accepted that a variety of alternative treatments to incineration can render certain categories of infec-tious waste safe, and can be less expensive and less damaging to the environment. These are generically known as “alternative treatments” and may involve heating by microwaves, steam under pressure or other technologies.

sharp, cytotoxic or cytostatic, medicinal but not cytotoxic/cytostatic, radioactive, mercury amalgam and anatomical (this last category is not of itself a hazard but does carry additional legislative requirements). Infectious waste could have one or more of these additional attributes. Each attribute or group of attributes will require segregation from others.

Color coding of clinical waste containersThe color coding of clinical waste containers is vital in the early stages of the journey of clinical waste and communicates the pathway which that particular container should follow to final disposal.

Yellow is indicative of bagged waste that must be incinerated as its final disposal. Category A infectious waste and medicinal (not cytotoxic/cytostatic) will be put into yellow containers. Other colors may be used in addition to a predominantly yellow container to indicate additional hazards: red indicates anatomical waste; purple indicates cytotoxic/cytostatic-containing waste. These must all be incinerated.

If bagged clinical waste can be rendered safe by alternative treatments to incineration, essentially category B infectious waste with no additional hazards, it is placed in orange containers.

Sharps containers have a yellow body with different color lids denoting more specific risks and appropriate disposal methods: with orange lids for category B infectious sharps, with purple lids for sharps with cytotoxic/cytostatic contamination, with yellow lids for sharps with medicinal (not cytotoxic/cytostatic) contami-nation. The volume of medicinal waste retained in a discharged syringe is judged sufficiently small that it can be disposed of as non-medicinal waste. Syringes with more medicinal remnants than this must not be discharged just so they can be disposed of as non-medicinal waste. Syringes contaminated with even resid-ual volumes of cytotoxic/cytostatic fluids must be disposed of as contaminated with these.

Infectious wasteThe definition of infectious waste is waste that “may cause infec-tion to any person (or animal) coming into contact with it”. This is not particularly helpful to clinicians who will appreciate the highly subjective nature of such a definition. It is a legal defini-tion that waste from an individual who has an infection is categorized as infectious when the waste is connected with that infection. For example, the urine of a patient with an ear infec-tion is not considered infectious; the urine of a patient with a urinary tract infection is considered infectious. That the micro-organisms infecting a highly susceptible patient in hospital may be of low pathogenicity and very unlikely to give rise to infec-tions in those who come into contact with the waste is not to be considered in this legal definition. Some body fluids may also be generically classified as infectious, blood for example would normally be classified as infectious unless it had specifically been screened; empty blood transfusion bags could, for example, be considered as offensive waste (see below) rather than infectious.

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effective chemical disinfection could achieve acceptable results at lower temperatures, this would save considerable energy but needs to be within a reliably high-quality assurance process. Suit-able processes and means of monitoring them on a real-time basis are needed. Another issue is that of the laundering requirements of a variety of establishments outside the acute healthcare sector. To what extent do the laundering requirements of, for example, a care home need to be the same as those for providers of linen for high-dependency healthcare? If different requirements are applicable to less acute healthcare, what should these be and how should they be graded across the spectrum this sector offers? As the non-acute care sectors generate a high proportion of laundry that cannot be thermally disinfected, mostly personal clothing, do they need to be chemically disinfected or is the dilution in a washing process sufficient, as has been judged adequate for staff uniforms?

For clinical waste, a significant future issue is the develop-ment of more alternatives to incineration. The vast majority of infectious clinical waste can be made safe by comparatively simple treatments before it progresses to a less environmentally damaging final disposal, which is also considerably less costly than the more traditional incineration. The category of “offen-sive waste” is currently very underused, probably caused by dif-ficulties in practical classification of waste into this category. Use of this classification would allow less rigorous transport and dis-posal at significantly reduced cost. A survey by the UK Royal College of Nursing (RCN) [9] estimated a national saving of over £5 million if 20% of what is currently infectious waste were to be reclassified as offensive waste. A similar logic applies to the overall reduction in the generation of infectious waste. Repeated surveys show that hospital staff are poor at distinguishing in practice between what should go in the domestic (black bag) waste stream and the infectious (orange bag) waste stream. The same RCN survey estimated that if 20% of infectious waste were reclassified as domestic waste, the savings would be nearly £9 million [9].

References

1 Sanderson, P.J. and Alshafi, K.M. (1995) Environmental contamination by

organisms causing urinary tract infection. Journal of Hospital Infection, 29,

301–303.

2 Department of Health (2012) Choice Framework for local Policy and Procedures 01-04 – Decontamination of linen for health and social care: Engineering, equip-ment and validation manual. Department of Health, London.

3 Wilson, J.A. et al. (2007) Uniform: an evidence review of the microbiological

significance of uniforms and uniform policy in the prevention and control of

healthcare-associated infections. Journal of Hospital Infection, 66, 301–307.

4 Department of Health (2010) Uniforms and Workwear: Guidance on Uniform and

Workwear Policies for NHS Employers, Department of Health, London.

5 Bates, C.J. et al. (1993) The efficacy of hospital dry cleaning in disinfecting mate-

rial contaminated with bacteria and viruses. Journal of Hospital Infection, 23,

255–262.

6 British Standards Institution (2002) BS EN 14065. Textiles. Laundry Processed

Textiles. Biocontamination Control System, BSI, London.

All infectious waste must be rendered safe as part of its dis-posal. The accepted definition of rendering clinical waste safe (excluding laboratory cultures) is a process that has been demon-strated to achieve at least a million-fold (6-log10) reduction in vegetative bacteria and a 10,000-fold (4-log10) reduction in bacte-rial spores. In addition to any microbicidal action, for patient confidentiality any patient identifiable data (such as names on specimen containers) should be rendered unrecognizable.

Types of disposalIncinerationClinical waste incinerators are becoming increasingly sophisti-cated and costly, not to ensure adequate microbial kill (any burning method would produce sufficient reductions), but to reduce the output of pollutant combustion products. Incinerators have two chambers; the first where the load is broken down into gaseous molecules at 800–1000°C and which feeds in to a second chamber with a temperature of at least 1100°C and a dwell time of at least 2 s, where large gaseous molecules are broken down even further. Gas scrubbing before emission will remove the majority of toxic pollutants such as sulfur dioxide and hydrogen chloride.

Variations on incineration are pyrolysis and gasification, where waste is heated in the absence (pyrolysis) or minimal amounts (gasification) of air in a primary chamber, and the resultant gases fed into a secondary chamber at 1100°C.

Alternative technologiesAlternatives to incineration tend to be less costly and, as they require less extensive plant, can be on or close to the site of waste production.

Microwave-based treatments generally shred the waste, add water (usually as steam) to the load and then use microwaves to produce atmospheric pressure steam in the waste to thermally disinfect it. This can be done on a continuous basis with an auger moving shredded waste past the microwave sources. Similar systems inject steam directly into the auger and use the energy from that to disinfect without extra energy from microwaves.

Clinical waste autoclaves use steam under pressure to treat batches of clinical waste. There also exist chemical disinfection systems where the disinfectant is added to shredded waste. If these are used, it should be ensured that one hazard in the waste (microbial) is not replaced with another hazard (chemical) and, while the disinfectant is effective, that it does not leave toxic sub-stances in the treated waste.

Conclusions

Healthcare laundry currently faces a number of issues that need to be resolved. For large-scale laundries, a crucial issue is that of energy efficiency, with the requirement for thermal disinfection being one of the more substantial uses of energy. If safe and

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Further reading

1 Department of Health (2006) Standards for Better Health, http://www.dh.gov.uk/

en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/

DH_4086665 (accessed June 12, 2012).

7 Department of Health (2010) The Health and Social Care Act 2008 Code of Prac-

tice on the Prevention and Control of Infections and Related Guidance, Department

of Health, London.

8 Department of Health (2012) Safe Management of Healthcare Waste, version 2.0,

Department of Health, London.

9 Royal College of Nursing (2011) Freedom of Information Report on Waste Manage-

ment, RCN Publication Code 004 108, Royal College of Nursing, London.