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

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74An investigation into the domestic laundry habits in EuropeTable 4-3 ContinuedSpainThe NetherlandsCode E-3 E-4 NL-3 NL-4Temperature (°C) 15 40 40 60Programme delicate cotton cotton cottonDetergent Ariël Alpine Ariël Alpine Ariël Color AriëlType of detergenttraditionalpowdertraditionalpowdercompactpowdercompact powderBleaching agents 1 yes yes no yesDosage (g) 120 120 65 65Load (kg) 3 3 3.3 kg 3.3 kgWater hardness (°dH) 9 9 9 9All cycles are run in a Miele W362 household washing machine.4.3 Selection of Microorganisms and laundry items4.3.1 LiteratureThere are only a handful of experts on this subject, and their scope is oftenconsiderably broader than the objective of this research. In most studies a relationshipbetween kitchen hygiene and food poisoning is established. Literatureon the hygiene effects of domestic laundry processes has not been found.In a bacteriological survey of the domestic environment, Finch [1] sampledvarious surfaces in the kitchen, bathroom, living room and hall of 21 homes.In more than half of the dishcloth, towel and teacloth samples, coagulasenegative Micrococcaceae and Bacillus spp. were present. Various bacteriawere found on the dishcloth, and Staphylococcus aureus was present on halfof the towel and teacloth samples. Later Speirs [2] did a similar study in 46homes. Speirs found different Enterobacteria, Pseudomonas, Bacillus andStaphylococcus aureus. More than 90% of the sampled tea and hand towelsand more than 94% of the sampled dishcloths had counts of >450 CFUs perarea (approximately 25cm 2 ). This represents a contamination hazard.Scott [3] showed that Escherichia coli, Salmonella spp., Klebsiella aerogenesand Staphylococcus aureus survive on clean and soiled cloth and that they areeasily transferred via cloths, hands and utensils. The survival rate on cleancloth was less than on soiled cloth, but in both cases regrowth was shown.Drying the cloth increased the number of bacteria. In a laboratory wash test
Hygiene effects of laundry processes in Europe 75using different kinds of disinfectants, Scott [4] also showed that the initialcounts of a three-day-old used dishcloth varied from 1.7*10 2 to 2.5*10 6CFU/cm 2 . The Total Plate Count increased after washing or disinfecting thesamples. Regrowth after storage was observed.Block [5] demonstrated that detergents containing a TAED-activated bleachwill not disinfect clothes when they are washed at 20°C or 30°C. This mightbe due to the pH differences in the suds, as Betz [7] discovered while investigatingthe anti-microbicidal effects of different bleaching agents at low washingtemperatures. Betz added different bleaching agents to a buffered bacteriaculture at 30°C and 40°C. Reductions of Enterococcus feacium of log 2 to log7 were found, depending on the bleaching agents that were used.The washing temperature seems to be even more important. Walter [6] conducteda study with used hospital and student bed linens. These linens wereinoculated with Staphylococcus aureus and Klebsiella pneumoniae andwashed at different temperatures. Klebsiella pneumoniae was easily washedout, but only after washing for 13 minutes at 60°C was Staphylococcus aureusno longer detectable. A wash heat exposure time of 8 minutes or a temperatureof 54°C was not sufficient to remove all the Staphylococcus aureus.4.3.2 Selection of Micro-organismsSeveral micro-organisms were selected for the test (based on the literaturestudy) consisting of a mixture of different groups of micro-organisms and onespecific one. The selected micro-organisms are known to be found on laundry.They are pathogenic or members in their group are pathogenic. Last but notleast, the detection of these micro-organisms must be practical and feasible.EnterobacteriaceaeEnterobacteriaceae are a very common family of bacteria with a few harmfulmembers such as the Salmonella group. Salmonella is reported as one of themost common causes of food poisoning. Enterobacteriaceae are found everywhereand are easy to culture. They are often used as an indicator of hygieneconditions. Finch [1] and Speirs [2] found Enterobacteriaceae on soiled dishcloth,tea towels and hand towels. Scott [3] and Block [5] also did researchwith cultures of this group of micro- organisms.
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Appendix CSettings of the 15°C Was
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