Cover Story HTO surfaces that do act as potential sources of contamination include: Childrenʼs playground equipment; shopping cart han-dles; faucets; chair armrests; telephones; and — of great importance in modern schools — computer keyboard keys. A recent study of microbial contamination levels in elementary school classrooms showed that water fountain toggles, pencil sharpener handles, computer keyboards and faucet handles were the most contam-inated with bacteria, while desktops, faucet handles and paper towel dispensers were most contaminated with viruses. In fact, Influenza A virus and norovirus were detected on 50 percent and 20 per-cent of surfaces, respectively. Most importantly, this study showed that contamination levels had a strong positive correlation with student absenteeism due to illness. We have seen that the microbial contam-ination can persist on HTOs such as just described, but this would not be a health threat if the contamination couldnʼt be eas-ily removed by hand-to-surface contact. Studies have been performed on the effi-ciency of pickup of bacterial contamination from surfaces. The overall conclusion from these stud-ies is that pickup efficiencies are very high at 30 to 40 percent from hard, non-porous, surfaces, such as faucets, but very low at less than 0.01 percent from porous objects, such as towels. The efficiencies of transfer of microbials to mouths from hands that have become contaminated by touching contaminated surfaces have been found to be about the same as the transfer efficiencies from hard surfaces to hands — 30 to 40 percent. The general picture developed so far is that: Microbial contamination of HTOs present in schools is high The contamination can persist a long time in a viable state Transfer of microbial contamination to hands from some common HTOs is very efficient Transfer from contaminated hands to mouths is very efficient. Thus, in the case of schools, HTOs can be efficient intermediaries for spreading person-to-person and person-to-home microbial contamination. The microbials can come from a wide variety of human sources and consist of a wide variety of pathogens, including antibi-otic-resistant species known as “super-bugs” that, at the present time, are no longer confined to hospitals and have become “community associated.” What can be done to minimize the spread of pathogens in schools and from school to home? To answer that question, some aspects of cleaning and disinfection need to be addressed. General Aspects Of Cleaning And Disinfection Considering only microbial contamination, cleaning and disinfection are basically two separate processes and thorough cleaning must be done prior to disinfectant use. Circle Product Information no. 207 on page 32 12 CM/Cleaning & Maintenance Management ® • September 2009
CMM – Archives Sept 2009: 12
