Cross contamination in low temperature processing5 February 2020
Following requests from the industry, The Guild of Cleaners and Launderers was asked to investigate hygiene in low temperature processing which led to research into the issue by Northumbria University. Ken Cupitt, FGCL, reports on the project and its interesting and thought-provoking conclusions
Northumbria University was asked to undertake the project as they had previous experience in this field and after consultation with The Guild, the team were confident of the benefits the research in terms of investigating any possible risks to public health throughout the industrial, commercial, retail and domestic sectors of our industry.
The breadth and scope of the project was heavily constrained by the very limited funding available, unfortunately, some promises at the outset for donations and support did not materialise, leaving The Guild and The Worshipful Company of Launderers as the main financial contributors.
The Guild is indebted to those industry suppliers and businesses who gave us their wholehearted practical support without which the project may not have got off the ground.
The project commenced in 2018 and after 44 months of laboratory testing and shop floor trials, The Guild received the report from Northumbria University in November and a summary of its results are as follows.
1. Sample fabrics were contaminated with a range of micro. organisms and stored before testing, Five days later tests proved these microorganisms had survived storage therefore had a long life on textile fibres following contamination.
2. Contaminated test pieces made from wool, cotton and polyester were then test washed under laboratory conditions in a wash process of 12 minutes at 30C and two rinses at ambient temperatures, one of five minutes and one of two minutes, The wool sample was processed in a detergent suitable for wool and the cotton and polyester test pieces were washed with a separate detergent suitable for those types of fibre.
2a). Following the process the fabric swatches were then tested for the survival of the microorganisms and it was found that all had survived.
2b). For a comparison purpose test the Northumbria University did a further wash test on other sample fabric test swatches but this time without a detergent but using the same temperature and times, Here again the microorganisms, not unexpectedly, survived the process.
3. In a third wash test, but just for cotton and polyester fabric swatches, a bactericide was added, The same process time and temperatures were used but this time following the process, the samples were free of bacteria, The wool fabric was not tested with the addition of a bactericide,
4. In a field trial at a drycleaner in the North East of England, using the solvent perchloroethylene, the Northumbria University test team found that no microbial growth was found inside the polythene garment covers. No microbial growth was found inside of the drycleaning machine drum, or in the solvent waste (It is thought that this was probably due to the toxicity of the Tetrachlorethylene solvent (Perc) to microorganisms, All sterile swatches, no matter what material type tested on, remained sterile after being drycleaned, From direct swabbing the front reception desk had the highest count of microorganisms, as expected, due to its increased contact with people and soiled garments.
5. Due to the projects financial constraints, no other drycleaning solvent user’s establishments were involved in any trials or tests.
The report showed that microorganisms, in the absence of a bleach or a bactericide, can not only survive low temperature processing but can remain relatively unaffected. This does of course raise concerns for the industry as a whole, as in the event of an epidemic or pandemic the process of textile cleansing could prove to be a factor in the spread of infection, rather than a service to help with hygiene standards. However, the study did not reveal any evidence of cross infection but this could still be an ongoing risk arising from particular low temperature processing and storage conditions.
While the investigation only looked at the mechanics of cleansing, the majority of textiles do undergo some form of finishing process which at one end of the spectrum – for example, calendaring – may ensure a hygienic product. However not all items are finished and in many cases only a limited process is applied such as automated finishing on garment formers where the timings, temperature and distribution of steam and heat can be extremely variable and therefore overall thermal disinfection cannot be expected.
Of particular concern is the cleansing of Health Service staff uniforms, many of which are now processed within a domestic environment in the UK, high street processing of personal wear and laundry, and on-premise laundries (OPLs) within the care homes sector, which may be uncontrolled and could therefore possibly present an infection/ cross infection risk.
The incorporation of a bactericide or PAP Peroxy bleach in the cleansing process might well ensure good disinfection in low temperature processing but this addition must not as a result affect the fibres and fabrics other than cleansing and hygiene. However, in the absence of legislative controls to ensure their use, either in the manufacture of low temperature detergents or in processing, disinfection hygiene will remain at best uncertain.
RESEARCH PROJECT INTO LOW TEMPERATURE PROCESSING
The Guild of Cleaners and Launderers has now issued the summary of the long awaited report from Northumbria University into low temperature processing.
Northumbria University has issued its report and a summary has been drafted for issue to members and the wording is back with the University research team for them to agree to the points described.
The report will be issued to Guild members when finally approved, which will be in next few weeks.
One important – and unexpected – result has come out of the findings and relates to the use of the solvent perchloroethylene. While perc can sometimes get a bad press, the Guild says that the report proves that when an item is cleaned in this solvent, no microorganisms survive the cleaning process. The report also found no evidence of bacteria surviving within the cleaning machine or in the solvent waste. No other solvent, other than water, was tested due to financial constraints.
WHERE DO WE GO FROM HERE
Roger Cawood comments: In March and May 2018 I wrote a two-part article on wetcleaning (http://www.laundryandcleaningnews.com/features/featurewetcleaningv- drycleaning-part-1-putting-the-record-straight-6097082/ and http://www. laundryandcleaningnews.com/features/featurepart-2-finishing-with-style-6195395/ ) in which I commented on the hygiene aspects of low temperature processing.
The resulting Guild/Northumbria study has now established that a range of pathogens, in the absence of a bactericide, can survive low temperature processes. Of particular interest is the fact that pathogens can survive even longer than 28 days on wool textiles, prior to processing, a major part of the dry/wetcleaners workload. they also survived for at least five days on all textiles, risking further cross contamination.
It is my belief that, bearing in mind that low temperature processing (both washing and wetcleaning) is continuing to rapidly expand, and is likely to continue to do so It is my opinion that a more wide-ranging, and detailed study, including finishing equipment and methodologies, is now needed to firmly establish the true nature of the risk, if any, to public health.
Going forward the industry, in my view, cannot afford to sit on the fence and hope that everything will be OK. We simply cannot afford to be found wanting in the event of the rapid spread of some virulent pathogen such as Ebola, or an influenza pandemic.
While the Northumbria study has provided invaluable data, for low temperature washing, the University was not in a position to investigate drycleaning as fully as water-based processing because it has no similar equipment for drycleaning trials. Tests for the survival of bacteria in drycleaning were carried out on site in a unit shop using perchloroethylene solvent
While the indications for perc look promising the results cannot of course be extrapolated to cover the other drycleaning solvents that are in use today at least one of which is known to support bacterial growth. The Guild is at present looking to see if we can find the funds to support a small additional study, to answer the issues raised.
Roger Cawood, FGCL, chief examiner drycleaning