Chapter 1: Risk Management and Safety in the Laboratory

Risk management

pertains to the process of ensuring and maintaining personal as well as environmental health and safety in the laboratory.

Standard operating procedures

must be detailed to include control of hazardous substances, risk assessments, and other health and safety information relevant to handling of specimens

cutting of one's finger or hand on microtome knives

One of the most common accidents in the laboratory involves

• chemical

• physical

• biological

Most hazards encountered fall into three main categories:

Chemical Hazards

Cleaning agents and disinfectants, drugs, anesthetic gases, solvents, paints, and compressed gases

Irritants

are chemicals that cause reversible inflammatory effects at the site of contact with living tissue, especially the skin, eyes and respiratory passages.

Corrosive chemicals

cause destruction or irreversible alterations when exposed to living tissue, or destroy certain inanimate surfaces (generally metal).

Sensitizers

• cause allergic reactions in some exposed workers, not just in hypersensitive individuals.

• may occur at work because of the high exposure level.

Carcinogens

are substances that induce tumors, not only in experimental animals but also in humans.

Toxic materials

are capable of causing death by ingestion, skin contact or inhalation at certain specified concentrations. These include methanol, chromic acid, osmium tetroxide and uranyl nitrate.

Flammable liquids

• should be stored in cabinets and safety containers that are approved by the Occupational Safety and Health Administration (OSHA).

True

True or False: Never mix different chlorine solutions or store them with cleaning products containing ammonia, ammonium chloride, or phosphoric acid. Combining these chemicals could result in release of chlorine gas, which can cause nausea, eye irritation, tearing, headache, and shortness of breath. These symptoms may last for several hours.

Cryogens

are used to produce substances with temperatures below -153°C (-243°F), such as liquid nitrogen and a boiling point of -196oC (-321°F), that are commonly used in laboratories.

Physical Hazards

• The most obvious are slips and falls from working in wet locations and the ergonomic hazards of lifting, pushing, pulling, and repetitive tasks.

• Other hazards often unnoticed are electrical, mechanical, acoustic, or thermal in nature. Ignoring these can have potentially serious consequences.

Electrical Hazards

are potentially life threatening but can be easily avoided.

True

True or False: If you see a person being electrocuted, DO NOT TOUCH THEM!

Biological Hazards

• refer to anything that can cause disease in humans, regardless of their source.

• include infectious agents and their toxins as well as contaminated solutions, specimens or objects.

Allergens

are one of the most important health hazards, yet they are frequently overlooked.

Molds and fungi

produce and release millions of spores small enough to be air, water, or insect borne which may have negative effects on human health including allergic reactions, asthma, and other respiratory problems.

Small spills

are defined as those that can be safely handled by the immediate staff.

Ergonomics

Laboratory work activities can introduce —- risk factors that are associated with muscular-skeletal disorders.

microscope

is one piece of equipment that is used by both the pathologist and the histotechnologist.

pathologist

examines the slide under the microscope to identify a disease process or an abnormality that will directly affect the patient's treatment.

histotechnologist

examines the same slide microscopically for quality control to determine whether all technical processes are done properly and if a slide of diagnostic quality has been achieved.

1. it must magnify the object

2. it must resolve the details of the object

3. it must make these details visible

To be useful, a microscope must accomplish three things:

compound light microscope

• is a microscope with more than one lens and its own light source.

• here are ocular lenses in the binocular eyepieces and objective lenses in a rotating nosepiece closer to the specimen.

Monocular Heads

• Only use one eyepiece when viewing the specimen. You are restricted if you want to use an LCD camera because this would occupy the eyepiece.

• light weight and are inexpensive.

Binocular heads

• have two eyepieces and are more convenient and comfortable to use.

• It is the most common choice.

Trinocular Heads

• have a third eyepiece tube that can be used by another person simultaneously or by an LCD camera.

• more expensive than the other two types.

Base

• provides support for the microscope.

• should be large and solid enough to allow the microscope to stand by itself.

Arm

supports and holds the magnifying and adjustment system. It can be used as a handle for carrying the microscope.

Stage

is the flat platform where the slide is placed for examination.

Substage

is located directly under the stage and holds the condenser and diaphragm.

Mechanical Stage

permits movement of the stage while holding the slide in the phase of focus.

Nosepiece

is located at the end of the body tube for holding the objectives.

Objectives

consist of a system of lenses located at the end of the body tube that is held in place by the nosepiece and is closer to the slide under examination.

Focal length

is the distance between outer lens of objective and the cover glass of the slide under examination.

Magnification

is the process that increases the size of the structure under examination. It is achieved by the use of the microscope's lens system.

160 mm

normal tube length

180 mm

Working Tube Length

Bright Field Microscopy

is generally used in compound microscopes, where light is either passed through, or reflected off, a specimen. Illumination is not altered by devices that alter the properties of light (such as polarizers or filters).

Dark Field Microscopy

• Dark Field illumination is a technique used to observe unstained and transparent samples causing them to be clearly visible and appear brightly lit against a dark, almost purely black background.

• blocks this central light with a condenser so that only oblique rays hit the object.

Phase Contrast Microscopy

• is an optical microscopy illumination technique in which small phase shifts in the light passing through a transparent specimen are converted into amplitude or contrast changes in the image.

• enhances contrasts of transparent and colorless objects by influencing the optical path of light.

• able to show components in a cell or bacteria which would be very difficult to see in an ordinary light or bright field microscope.

• reveals many cellular structures that are not visible with a simpler bright field microscope and makes it possible for biologists to study living cells and how they proliferate through cell division

True

True or False: The use of phase contrast does not require staining to view the slide.

Polarized Light Microscopy

• is a contrast-enhancing technique that improves the quality of the image obtained with birefringent materials when compared to other techniques such as bright field microscopy, phase contrast microscopy and dark field microscopy.

• designed to examine specimens that are visible primarily due to their optically anisotropic character.

1. The polarizer situated below the specimen stage usually fixed in the left-to-right, East-West direction

2. The analyzer, usually aligned North-South but again rotatable on some microscopes, is located above the objectives and can be moved in and out of the light path as required.

two essential components of a polarized light microscopy:

Fluorescence Microscope

• refers to any microscope that uses fluorescence to generate an image.

• is a precision instrument intended for microscopic detection of tubercle bacilli in specimens in the routine diagnostic TB laboratory.

• requires intense, near-mono-chromatic, illumination which some widespread light sources, like halogen lamps cannot provide.

1. xenon arc lamps

2. mercury-vapor lamps with an excitation filter

3. lasers

4. high-power LEDs

Four main types of light source are used in Fluorescence microscope:

fluorescein or rhodamine

Examples of commonly used fluorophores are?

Electron Microscope

• is a microscope that uses a beam of accelerated electrons as a source of illumination.

• functions similarly to an optical scope except that, instead of visible light, a stream of electrons is used to illuminate the specimen.

Transmission Electron Microscope

• works on the same principle as an optical microscope but uses electrons instead of light and electromagnets instead of glass lenses.

• It has high magnification and high resolution.

• can achieve better than 50 nm resolution and magnifications of up to about 10,000,000x

Scanning Electron Microscope

• uses electron illumination and looks at the surface of bulk objects by scanning the surface with a fine electron beam.

• The image is seen in 3-D

• It has high magnification and high resolution.

True

True or False: Procedures involving volatile toxic substances and those involving solid or liquid toxic substances that may result in the generation of aerosols should be conducted in a fume hood or other suitable containment device.

monthly

Eye wash station, safety shower and first aid kits should be standard facilities in a laboratory. Fire extinguishers, emergency shower systems, emergency eye washers, first aid, emergency blankets, and hoods must be checked —-

True

True or False: To avoid the unnecessary purchase of chemical materials, a detailed list of chemical materials must be prepared. Only a minimum amount of volatile chemicals must be kept in the laboratory.

True

True or False: All chemical material must be labeled with the name, characteristics, danger level, and precautionary measures.

False

True or False: Potential exposures to chemical hazards can occur both after use and with poor storage.

True

True or False: Certain silver solutions may explode upon aging, which is why they should never be stored after use.

picric acid

Explosive chemicals include?

False

True or False: Explosives are harmless by themselves, but may initiate or promote combustion and present a serious fire risk when in contact with certain substances.

polyethylene or other chemically resistant material

To minimize hazards from accidental breakage of apparatus or spills of toxic substances in the fume hood, they should be stored in pans or trays made of?

False

True or False: water should be added to concentrated acids in order to prevent splashing, and should be done under a chemical fume hood.

False-

True or False: Bleach solutions should be autoclaved.

Combustibles

• substances whose vapors will ignite at or above a certain temperature (or flash point) or in the presence of an ignition source.

• liquids pose little risk of fire under routine laboratory conditions, but they will burn readily during a fire.

True

True or False: In dealing with a laboratory fire, all containers of infectious materials should be placed into autoclaves, incubators, refrigerators, or freezers for containment.

Ground-Fault Circuit Interrupters (GFIs)

are designed to “trip” and break the circuit when a small amount of current begins flowing to ground.

True

True or False: Fixed specimens have a much less risk because nearly all infectious agents are deactivated by histological fixation, although tissues must be thoroughly fixed for this to happen.

Prions

are infectious agents that cause spongiform encephalopathies such as Creutzfeld-Jakob disease (CJD), scrapie and mad cow disease.

True

True or False: Tissue from patients with suspected CJD can be decontaminated by immersing the specimen in formalin for 48 hours, followed by treatment in concentrated formic acid for 1 hour, and additional formalin fixation for another 48 hours.

True

True or False: Biological safety cabinet(s) must be certified within the last 12 months of use.

10% bleach solution

The work space and equipment should be decontaminated with?

True

True or False: With laboratory chemicals, the most common accidents requiring first aid are ingestion, eye contact and extensive skin contact.

False

True or False: Scanning Electron Microscope reveals many cellular structures that are not visible with a simpler bright field microscope and makes it possible for biologists to study living cells and how they proliferate through cell division.

True

True or False: Because of the lower magnification, each field examined under fluorescence microscopy is larger in area than that seen with light microscopy, thus reducing the time needed to examine a slide.

True

True or False: It is recommended that the fluorescent bulb be changed after 100 hours of use.

True

True or False:
Scanning electron microscopes are radiation-generating devices and should be at least inventoried