Biological and physical laboratory safety

Standard precautions

The CDC continuously monitors infection and disease in the United States. The CDC has also recommended preventive practices called standard precautions. These precautions apply to all patient care, regardless of the suspected or confirmed infection status of the patient. The precautions also apply to any setting where healthcare is delivered. The precautions are designed both to protect the healthcare provider and prevent the healthcare provider from spreading infections among patients.

Standard precautions include the following five elements:

• Hand hygiene
• Use of PPE (e.g., gloves, gowns, masks, eye protection)
• Safe needle practices
• Safe handling of potentially contaminated equipment or surfaces in the patient environment
• Respiratory hygiene/cough etiquette

Hand hygiene

According to the CDC, hand washing is the single most effective means of preventing and spreading infection. Proper hand sanitation protects you, your patient, and your co-workers because it removes or kills potentially pathogenic organisms from the skin surface. In the laboratory, it is essential to wash your hands with soap and water or use hand sanitizer in the following situations:

• When entering the laboratory or before leaving the laboratory
• Before putting on gloves and after removing gloves
• After contact with body fluid
• Before and after eating
• Before and after using the restroom

Bloodborne pathogens standard

In 1991 OSHA published the bloodborne pathogens standard, which addressed ways to minimize or eliminate the risk of bloodborne pathogen exposures. The bloodborne pathogens standard was created in response to the significant health risk associated with workplace exposure to blood and other potentially infectious materials (OPIMs) that may contain bloodborne pathogens. The bloodborne pathogens standard covers all employees who could “reasonably anticipate contact with blood and other potentially infectious materials as the result of performing their job duties.” Hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) are constant hazards to clinical laboratory personnel.

Bloodborne pathogens are transmitted through exposure to blood and body fluids, which are the primary substances handled in the laboratory. Urine is not classified as OPIM under the standard unless it is visibly contaminated with blood; because contamination can be hard to rule out, urine specimens should still be handled with standard precautions as a possible source of exposure.

The bloodborne pathogens standard requires that the laboratory employer have a written exposure control plan that proves steps have been taken so that the following information is available to protect employees:

• Written job categories of employees at risk of exposure to blood (laboratory workers are considered “high risk”)
• HBV vaccination guidelines and records for each employee at risk
• Record of initial and annual bloodborne pathogens and safety training for each employee (including proper use of safety needles)
• Definition and listing of safe work practices: personal protective equipment (PPE) for all lab personnel (fluid-impermeable lab coats that do not leave the laboratory area, gloves, and face protection), and labeling of biohazard sharps and waste containers along with their proper disposal
• Sharps injury log of all work-related needlesticks and exposures to blood, with medical intervention after exposure incidents
• Written plan to maintain privacy of the individual exposed to blood
• Documentation of employee input on new safety devices

Proper handling and disposal procedures for blood and other potentially infectious materials

The following guidelines are required for handling blood and OPIMs:

• Use the appropriate PPE.
• Handle and process all specimens as if they contain infectious material.
• Wipe the outside of specimen containers with a germicide.
• Clean up spills using a disinfectant.
• Immediately dispose of any chipped or broken glassware into a sharps container using appropriate safety methods to prevent accidental punctures.

Dispose of all biohazardous waste according to state and federal guidelines. Disposal methods include treatment by heat, incineration, steam sterilization, chemical treatment, or other equivalent methods that will render the waste inactive before it is placed in a landfill. Disposal guidelines include the following:

• Infectious agents may be inactivated (such as using the autoclave) before disposal.
• Blood and potentially infectious materials mixed with chemicals are considered mixed waste. If possible, the infectious material should be inactivated, and the disposal should follow the chemical disposal guidelines.
• Biohazardous waste must be collected in impermeable, red polyethylene or polypropylene biohazard-labeled bags or containers and sealed.
• Used, disposable sharp items must go sharp-end first into a labeled, leakproof, puncture-resistant sharps container kept close to the work area. Never reach inside a sharps container; replace it once it’s about 75% full, and close the lid securely before removing it.
• Workers who handle biomedical waste should observe standard precautions.

First aid measures after an exposure

If a blood or OPIM exposure occurs, a medical assistant must know the immediate steps to take. If you have an exposure to blood or OPIM, do the following:

• With a needlestick or an exposure to a cut or a body surface, wash the area with soap and warm, running water for 10 to 15 minutes as soon as possible after the exposure. Chlorine-based antiseptics and 10% iodine solution can also be used to clean the area.
• Flush splashes to the nose or mouth with water.
• Irrigate the eyes. Continuously flush them with water as soon as possible for a minimum of 15 minutes using an eyewash station.
• Report the incident to the supervisor and immediately seek medical treatment.

Physical hazards

Physical hazards in the laboratory can be classified as electrical, fire, and mechanical hazards.

Electrical hazards

Electric shock is a threat when any electrical equipment is in use. It is imperative to keep all electrical equipment in proper repair and always follow manufacturers’ instructions.

To prevent electrical hazards, do the following:

• Use surge protectors.
• Inspect all cords and plugs frequently. Do not use damaged cords or plugs.
• Never use extension cords.
• Do not overload circuits.

Unplug the electrical device before servicing, and never operate electrical instruments with wet hands. If a sink is nearby, make sure electrical cords do not come in contact with the water supply. Workplace safeguards, such as signs and labels, should be placed on specific electrical hazards.

Fire hazards

Open flames are rarely used in a laboratory anymore, but the potential for fire still exists. Fires may be ignited by smoking, heating elements, and sparks from electrical connections. Flammable materials should not be stored near any source of ignition. All laboratory personnel should be familiar with the locations of fire extinguishers and fire safety blankets. Fire extinguishers used in the laboratory are typically the dry chemical, carbon dioxide (CO2), or halon type. Dry chemical extinguishers are usually the multipurpose ABC type, effective on Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical) fires. CO2 and halon extinguishers, by contrast, are effective on Class B and C fires only. Extinguishers should be inspected regularly by a licensed inspector and replaced or recharged if used. The medical assistant may be responsible for maintaining records on the care and maintenance of fire extinguishers.

Fire safety blankets can be used to smother flames on burning clothing. However, a victim should not be wrapped in a fire blanket because it may intensify burns. Instead, the flames should be patted out or the victim directed to stop, drop, and roll on the blanket.

Emergency phone numbers should be posted on the wall near the telephone, and all personnel should know the locations of fire alarms, the fire escape routes, and procedures to follow if exits are blocked. Periodic fire drills should be conducted, and hallways and exits should be kept free of clutter.

Mechanical hazards

Mechanical hazards arise from the use of laboratory equipment. Care should be exercised when using equipment with moving parts, such as a centrifuge, which separates liquids from solids by spinning samples at high speed, forcing heavier constituents to the bottom of the tube. Centrifuges present a hazard not only from moving parts but also from glassware that might break during centrifugation and from aerosols created if tubes are not capped tightly.

Care should also be exercised when using equipment that relies on pressure, such as autoclaves. Autoclaves are used to sterilize metal instruments, microbiologic media, and some microbiologic waste. Autoclaves present a danger if opened prematurely before the pressure has come down to a safe level.

Although centrifuges and autoclaves often have built-in safeguards, such as locks that prevent entry until the environment is safe, improper care of the equipment can cause safety measures to fail.