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« Last post by cschwab on February 07, 2013, 06:26:59 PM »
Environmental impact of dialyzer reuse and single-use practices
Reuse of dialyzers raises a number of important environmental concerns. Spillage of heated contaminated water used for dialyzer rinsing into the sewer system; increased plastic waste from packaging materials used for reuse chemicals; and additional waste generated from disposable items such as masks, gloves, test strips, plastic aprons, and labels, are all important potential pollutants associated with reuse. We predict that approximately 6.4 million gallons of peracetic acid and 1 million gallons of aldehydes are released into the environment every year because of reuse in the United States, assuming that only 40% of patients are reusing dialyzers based on informal estimates from 2005 (4) and that the prevalence use rate of peracetic acid and aldehydes is 72 and 24%, respectively, based on national surveillance data from 2002 (3). Figure 1 provides a hypothetical illustration of how yearly generation of liquid waste from germicides that are used for dialyzer reprocessing in the United States would vary with increasing proportion of patients who reuse dialyzers. Similarly, Figure 2 provides a hypothetical illustration of how yearly generation of cardboard and plastic related to packaging of two types of peracetic acid concentrates (45) for dialyzer reprocessing in the United States would vary with increasing proportion of dialysis facilities that practice reuse. These estimates are provided, because peracetic acid is the most widely used germicide for dialyzer reprocessing.
Hypothetically predicted yearly generation of liquid waste from germicides used for dialyzer reprocessing in the United States. For these calculations, the following assumptions were made: (1) Projections were made for 309,269 patients who received hemodialysis in the United States, which is based on point prevalent estimates (as of December 31, 2004) obtained from the US Renal Data System (USRDS) 2006 annual report (48); this translates into approximately 48.2 million yearly dialyses performed on an average of three weekly sessions; (2) the proportion of centers that use peracetic acid (72%) and aldehydes (formaldehyde and glutaraldehyde [24%]) was derived from the 2002 national surveillance of dialysis-associated diseases in the United States (3); (3) the volume of working-strength peracetic acid (at 3%) used to clean and disinfect a high-flux dialyzer was estimated at 1.743 L, using the specifications and instructions for use of the Renalin Cold Sterilant Concentrate for use with the Renatron Dialyzer Reprocessing Systems (49); (4) the volume of bleach (0.1 to 1% sodium hypochlorite) used to clean a high-flux dialyzer (Optiflux F160NR, Fresenius Medical Care) was estimated at 1.5 L, and the projections were restricted to reuse practices that disinfect dialyzers with aldehydes; and (5) the volume of working-strength aldehydes (at 1 to 4%) used to disinfect a high-flux dialyzer (Optiflux F160NR) was estimated at 0.756 L, assuming that it is necessary to run three dialyzer volumes of the working solution of aldehydes through the dialyzer (blood and dialysate compartment volume of 0.252 L) to achieve the desired final germicide concentration (50) and that the reprocessing procedure is automated and not manual. The dots correspond to the 60% prevalence rate of dialysis facilities that practice reuse in the United States, obtained from the 2002 national surveillance estimates (3).
Hypothetically predicted yearly generation of cardboard and plastic waste related to peracetic acid dialyzer reprocessing in the United States. For these calculations, the following assumptions were made: (1) Projections were made for 4732 dialysis facilities that care for patients in the United States, which is based on point prevalent estimates (as of December 31, 2004) obtained from the USRDS 2006 annual report (48); and (2) the yearly cardboard and plastic weight (85 to 354 kg) was generated from a study that compared packaging waste from standard (Renalin Cold Sterilant) versus concentrated (Renalin 100) peracetic acid in a dialysis facility that cares for a monthly average of 78 patients (45). The dots correspond to the more recent hypothesized prevalence rate of dialysis facilities that use peracetic acid in the United States (3).
Single use of dialyzers also poses a challenge to the dialysis community of formulating plans for effective solid waste management with minimal adverse impact on the environment. In a report published by Minntech Corp., a company that is involved in dialyzer reprocessing, it was estimated that, in 1997, hypothetically solely single-use practices in the United States would have resulted in 17 to 18 million pounds of waste generated from dialyzer components that year alone (46). We examined the magnitude of dialyzer waste generated hypothetically from single-use dialyzer practices. For these calculations, the various components of a polysulfone dialyzer (Optiflux F160NR; Fresenius Medical Care, Lexington, MA) were weighed, including the dialyzer housing, the blood and dialysate caps, and the outer package, totaling 0.22 kg. Figure 3 provides a hypothetical illustration of how yearly generation of dialyzer-related polymer waste in the United States would vary with increasing percentage of patients shifting toward single-use practices.
Hypothetically predicted yearly generation of solid waste from dialyzers in the United States. For these calculations, the following assumptions were made: (1) Projections were made for 309,269 patients who received hemodialysis in the United States, which is based on point prevalent estimates (as of December 31, 2004) obtained from the USRDS 2006 annual report (48); this translates into approximately 48.2 million yearly dialyses performed on an average of three weekly sessions; and (2) the solid waste generated from dialyzers was calculated by weighing the various components of a polysulfone dialyzer (Optiflux F160NR, Fresenius Medical Care), including the dialyzer housing, the blood and dialysate caps, and the outer package, totaling 0.22 kg. Polymers originating from the dialyzer include polycarbonate (dialyzer housing and blood and dialysate caps), polysulfone (hollow fibers), polyurethane (potting compound), and polyvinyl chloride (outer packaging material). The dots correspond to the 40% prevalence rate of dialysis facilities that practice single use in the United States, obtained from the 2002 national surveillance estimates (3).
Figure 4 introduces the concept of a
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