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Prudent Practices in the Laboratory: Handling and Disposal of Chemicals
(e.g., gloves, pipettes, and tips). In many cases, the small quantities of infectious waste on such labware can be disinfected safely with bleach or other chemical disinfectant (e.g., by soaking overnight). The disinfected waste can then be treated as a chemical waste. The worker must check with the state or regional EPA office to determine if a treatment permit is required for chemical disinfection of chemical-biological waste.
Autoclaves can be used to steam-sterilize infectious waste but should be tested routinely for efficacy. Autoclaving does not require an EPA permit. Care must be taken because autoclaving of chemical-biological waste at 120 to 130 °C may result in the volatilization or release of the chemical constituent. Additional waste containment may be needed to minimize chemical releases, but it can interfere with steam penetration into the waste load and sterilization. Before autoclaving untested waste streams containing volatile chemicals, a small load should be processed while monitoring the air emissions.
Autoclaving waste containing flammable liquids may result in a fire or explosion. (It should also be noted that steam sterilization of waste that contains bleach may harm an autoclave.) To autoclave voluminous chemical-biological waste streams, it may be appropriate to dedicate an autoclave room with ample ventilation and to restrict access.
The autoclaved chemical-biological waste can be managed as a chemical waste. After autoclaving, the biohazard markings on the container should be defaced or the material overpacked in a second container to indicate that the waste has been sterilized.
Similar precautions should be observed when using microwaves for decontamination. Although still under development, ultraviolet peroxidation may have the capacity to both sterilize and destroy certain chemicals in the waste. Chemical treatment permits may be required.
7.C.2.4 Disposal of Chemically Contaminated Medical Waste and Sharps
Laboratories that work with human blood must adhere to OSHA's Standard for Occupational Exposure to Blood borne Pathogens (29 CFR 1910.1030), which requires waste containment, marking, and labeling. The OSHA standard also regulates waste disposal from laboratories that manipulate human immunodeficiency virus (HIV) or hepatitis B virus (HBV). In general, such waste that is chemically contaminated can be incinerated with other medical waste or can be autoclaved and managed as a chemical waste.
Waste hypodermic needles and other "sharps" (e.g, scalpels and razor blades) need to be contained in a puncture-resistant waste collection container. Sharps should be destroyed by incineration or by grinding as part of the disinfection treatment. Incineration of chemical or drug-contaminated needles in a medical waste incinerator is appropriate if the waste is not an EPA-regulated chemical waste and if the chemical's toxicity or contamination is low. Needles and other sharps that are contaminated with toxic chemicals and infectious agents or blood can be autoclaved or disinfected on site (see the precautions above), and then managed as a chemical waste. The waste container's biohazard symbol and markings should be defaced after autoclaving or disinfection to indicate that the waste has been sterilized. Noninfectious needles and sharps with high chemical toxicity or contamination are accepted by chemical incinerators.
Some biomedical research generates materials contaminated with blood and antineoplastic drugs. Incineration of these materials as medical waste is appropriate if the level of chemical contamination is low, which is typical. In some cases, chemical disinfection and treatment can be combined to destroy both infectious agents and the antineoplastic drug. It should be noted that unemptied source containers of some antineoplastic drugs are EPA-listed hazardous waste and must be managed as a regulated chemical waste.
7.C.2.5 Minimization Methods for Chemical-Biological Waste
Waste minimization methods used for chemical waste can be used to reduce or eliminate the chemical hazard of chemical-biological waste. Some laboratories that generate biohazardous waste have replaced disposable items with reusable supplies, which are disinfected between uses.
For biological waste, waste minimization can be accomplished best through careful source separation of biological waste from other waste streams. When state guidelines for defining infectious waste do not exist, it is important for laboratories to define carefully those biological wastes that can be disposed of safely as noninfectious within the framework of the CDC/ NIH guidelines (U.S. DHHS, 1993). Training workers to identify and separate biological waste will prevent its inadvertent mixing with other waste streams and normal trash.
The management of radioactive-biological laboratory waste (shown in Figure 7.2c) can be difficult because of limited on- and off-site disposal options.