Laundry treatments at high and low temperatures

The process of laundering contaminated linen (including clothing) requires treatment that is effectively a wash-based disinfection process, and is required to avoid cross infection from re-used items.

Contaminated linen is generated by hospitals, care homes, nursing homes and similar facilities, as well as in the home care setting; anywhere that care of the sick and infirm is undertaken. The nature of laundry soiling depends on the source, and at the most extreme levels, eg in hospital and nursing home environments, is likely to include blood, wound exudates, sputum, saliva, sweat and urine, as well as vomit and faeces. It is also important to recognise that bloodstained body wastes such as urine may also serve as a potential source of infection. The nature of the soiling will determine how contaminated items are sorted and processed, and current UK categorisation recommends sorting into used linen (soiled and foul), infected linen and heat labile linen categories.

Infected linen is defined as linen derived from known infectious patients, including those with HIV, hepatitis B, C and other infectious agents. Linen can be made safe by washing to remove any contaminating body fluids, but it is often not practical to wash domestic linen at high temperatures because of the heat lability of fabrics. Recommended wash conditions, based on the levels of soiling, are as follows:

Current recommended treatments to ensure cleaning and disinfection of used (soiled and foul) linen

• A 65oC temperature hold for a minimum of 10 minutes within the wash cycle; or
• 71oC for not less than 3 minutes.

• Mixing time must be allowed to ensure heat penetration and assured disinfection. A sluice cycle must be added in to the cycle when dealing with foul linen.
• Recommended treatment to ensure disinfection of infected linen (mainly applicable to the healthcare setting):
• Linen in this category should not be sorted, other than in a red, water-soluble bag - this then placed in an outer polyester or nylon carriage bag. Infected linen may be stored in different bags in other parts of the UK, eg clear with red stripes are used in parts of Scotland. Local policy should be checked and adhered to.
• Inner bag should be removed from the outer bag only at the point of transfer to the washer-extractor, followed by the outer bag.
• Storage of infected linen must be done in a secured area, prior to washing.
• The same wash temperature profile as used for used (soiled and foul) linen is thought sufficient to inactivate HIV, but the evidence is less certain for hepatitis B. The wash temperature, coupled with the dilution factor, should render linen safe to handle on cycle completion.

Current recommended treatment to ensure disinfection of heat labile linen

• These items need to be washed at ~40oC, so the wash temperature is insufficient to disinfect, and chemical alternatives are required;
• Addition of hypochlorite may be possible, but efficacy may be reduced by the presence of soiling, detergents and alkalis in the main wash;
• Disinfection with hypochlorite is only reliable if the linen can tolerate its addition and if sodium hypochlorite is added during the penultimate rinse of the cycle;
• A final concentration of 150 ppm available chlorine must be achieved for a minimum of 5 minutes exposure time.
• Laundering contaminated items in the community setting

Existing guidance states that in the community setting or elsewhere without access to specialist services, contaminated clothing or linen should be treated in one of the following ways:

• *Washed with detergent using the hot wash cycle of a domestic washing machine to a temperature of at least 80oC; or
• Dry cleaned at elevated temperatures, or dry cleaned cold followed by steam pressing; or
• Incinerated if items cannot be effectively washed as described above
• *Dilution is an important part of the washing process and therefore machine overloading should be avoided. If washing by hand is unavoidable, household rubber gloves must be worn.

The reality of domestic laundering may be somewhat different from this ideal for those living with BBV in the home environment. Domestic washing machines rarely have an 80oC setting. If this is the case, if contamination is not excessive, all potentially contaminated linen should be washed at the highest possible temperature recommended for that particular fabric. The combination of temperature (when more than 40oC), detergent action and dilution effect during the wash and rinse steps, will contribute to the process of soil removal and disinfection for the washed item.

Recommendations for work wear laundering are also available from the Department of Health