an investigation of domestic laundry in europe - habits ... - SIFO

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100An investigation into the domestic laundry habits in Europeindustry and others, some considerations have to be made. Further research isrequired to fine tune the test method itself as well as the sampling method andthe choice of samples in particular.SamplingThe paper shredder is able to cut the samples into small pieces but it is not apractical apparatus. The sharp side has many small parts - which are difficultto disinfect. The risk of contaminating the samples while cutting them is real.When the research objective is to get an indication of the presence of microorganisms,this contamination risk may be acceptable (within limits). Whenthe object is to determine the amount of micro-organisms, the paper shredderis not the best option. The shredder cannot be used to cut items like a sockbecause of the shape. The pieces would not have the same length. That is whythis sample was cut into pieces by hand.The selection of samplesFour different laundry items were chosen for this experiment: a diaper, a dishcloth,a handkerchief and a sock. The diaper and the dishcloth proved to begood samples. They are flat and rectangular pieces of laundry which are easyto cut. The expected bacteria were present in abundant amounts. The handkerchiefis also flat but slightly fragile. Cutting is difficult because the material isa thin layer. The Staphylococcus aureus that were expected were actuallyfound. The micro-organisms that were expected, the yeasts and fungi, werenot found in the socks that were used in these tests. Various micro-organismswere present and some of them disturbed the enumeration of Staphylococcusaureus. This item could be left out of further experiments because it proved tobe an ineffective sample.Is natural contamination a good way to see a hygiene effect?The main problem with natural contamination is that the nature and degree ofcontamination is difficult to control. During this study the amount of microorganismsthat were found prior to conducting the tests was more or less thesame. This means higher levels in the diaper and dishcloth samples and fewermicro-organisms in the sock and handkerchief samples 19 .19 Health regulations state that a reduction of at least log 5 or log 6 is neededfor good disinfection. To find reductions of this magnitude, the unwashedsamples should have a colony count of at least log 6. Only the diaper anddishcloth samples in this study (using naturally soiled laundry) meet thesecriteria for evaluating the Total Plate Count and the Enterobacteriaceae. In allother cases the colony count is so low that an artificial contamination wouldbe needed to investigate the level of disinfection.
Hygiene effects of laundry processes in Europe 101The selection of micro-organismsEnterobacteriaceae are easily removed from the laundry items, but there arestill some bacteria left after washing. They are spread throughout the washingmachine and the laundry items. Washing at 60°C reduces the amount of Enterobacteriaceaealmost to zero.In general, washing reduces the amounts ofBacilli considerably. There is nevertheless one exception. In one sample Bacilluscereus was found. Bacillus cereus proved to be a bacteria which survivesthe washing process at 40°C and even at 60°C. It is to be expected that itwould also survive at lower temperatures. Only washing at 60°C with bleachwill remove Staphylococcus aureus from the laundry items. This is exactlywhat Walter et al.[6] discovered. Fewer Staphylococcus aureus are removedwhen washing at 15°C than when washing at 30°C or 40°C.The Total PlateCount showed that even after washing with bleach at 60°C, bacteria are left inthe laundry. The Total Plate Count gives a good impression of the overall hygienequality. Throughout the tests, no high numbers of yeasts and fungi werefound. With the small numbers in these tests it seems that even a 60°C washwith bleach does not remove all yeasts. Fungi are removed more easily. Fungiwere found only after a wash at 15°C. It appears that bleach has some extraeffect.
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Page 119 and 120: Appendix ASurvey of domestic laundr
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Page 129 and 130: Appendix CSettings of the 15°C Was
Page 131 and 132: Appendix DSettings of the 30°C Was
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