Alternative Room Disinfection Modalities –Pros and Cons - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 197

and potentially carcinogenic to humans [ 76 ]. Formaldehyde is also extremely
irritating and both a dermal and respiratory sensitizer [ 98 ]. These undesirable
properties have limited its use as a chemical fumigant. Some other chemicals that
have been considered were hydrogen peroxide, hydrogen peroxide and silver dry
mist, ozone, superoxidized water (Sterilox) and chlorine dioxide. Ozone appears to
be limited in its effectiveness as a fumigant, and Sterilox was only evaluated in one
study with modest success [ 56 , 58 ]. A major advantage of hydrogen peroxide is that
it breaks down into oxygen and water, leaving no toxic residues [ 76 ]. One vendor
claims that the addition of silver to hydrogen peroxide provides residual inhibition
of microbial growth; however, no independent confirmation was located.
While fumigants can be successful in killing microorganisms, some chemical
agents have been found to be more effective than others in certain test environments
[ 80 ]. For example, chlorine dioxide achieved a higher kill rate on test samples of
industrial carpeting than did hydrogen peroxide. On the other hand, chlorine
dioxide is more likely to bleach the color from exposed materials and is more
toxic than hydrogen peroxide [ 61 ]. While these fumigants have demonstrated high
kill rates, in occupied hospital rooms, environmental surfaces will be constantly
re-contaminated. CDC does not recommend chemical fogging for general infection
control in routine patient-care areas because of the issue of recontamination and the
lack of evidence that chemical fogging will reduce nosocomial infection rates
[ 22 ]. While the CDC has not taken a position on the newer approaches to chemical
fumigation, these approaches have yet to provide convincing evidence of effec-
tiveness in lowering infection rates or in their ability to be used safely.
Another issue is that, while chemicals such as chlorine dioxide effectively kill
viable microorganisms, they will not affect the toxicity associated with non-viable
microorganisms and their endotoxins or mycotoxins [ 57 , 99 ]. This is an important
limitation because the primary health effect from mold exposure is an allergic
reaction, not an infection [ 100 ]. So unless water infiltration or other sources of the
mold are eliminated, fumigation will have little benefit.
Fumigation is being considered because gases and vapors can permeate areas
that are not easily reachable. However, this characteristic also means ventilation
ducts, plumbing fixtures, doors, windows and any other openings must be sealed
with a material that will resist penetration. The problem associated with blocking
ventilation supply, return and exhaust ducts is that it will disrupt the air balance
in all rooms served by the same blowers. This could change room pressurization in
other locations, including isolation rooms. Also, Rice and others have discovered
problems with room leakage in many healthcare facilities [ 49 , 50 , 52 ]. Blocking
ventilation ducts causing changes in room pressurization or increasing room leak-
age could contribute to infection spread [ 101 ]. The issue of disruption to the
building ventilation systems has not been addressed by fumigation equipment
vendors.
One of the most important measures of disinfectant effectiveness would be
the demonstration of a reduction in HAI rates. As of this writing only one study
demonstrated a significant reduction in HAI rates, and by the authors own admis-
sion, this study had severe design issues that prevented them from linking the rate