All materials contaminated with potentially infectious agents must be decontaminated before disposal. These
include unused portions of patient specimens, patient cultures, stock cultures of microorganisms, and disposable sharp instruments, such as scalpels and syringes with needles. Infectious waste may be decontaminated by use of an autoclave, incinerator, or any one of several alternative waste-treatment methods. Some state or local municipalities permit blood, serum, urine, feces, and other body fluids to be carefully poured into a sanitary sewer. Infectious waste from microbiology laboratories is usually autoclaved on-site or sent for incineration, however.
In 1986, the EPA published a guide to hazardous waste reduction to limit the amount of hazardous waste generated and released into the environment. These regulations call for the following:
Recently, several alternative waste-treatment machines were developed to reduce the amount of waste buried in landfills. These systems combine mechanical shredding or compacting of the waste with either chemical (sodium hypochlorite, chlorine dioxide, peracetic acid), thermal (moist heat, dry heat), or ionizing radiation (microwaves, radio waves) decontamination. Most state regulations for these units require at least a sixfold reduction in vegetative bacteria, fungi, mycobacteria, and lipid-containing viruses and at least a fourfold reduction in bacterial spores.
Infectious waste (agar plates, tubes, reagent bottles) should be placed into two leak-proof, plastic bags for sturdiness (Figure 4-6); this is known as double-bagging in common laboratory jargon. Pipettes, swabs, and other glass objects should be placed into rigid cardboard containers (Figure 4-7) before disposal. Broken glass is placed in thick boxes lined with plastic biohazard bags (Figure 4-8); when full, the box is incinerated or autoclaved. Sharp objects, including scalpels and needles, are placed in Sharps containers (Figure 4-9), which are autoclaved or incinerated when full.
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