Notes: Chemical and Waste Management in Modern Dental Assisting (Chapter 23)
Exposure Hazards in the Dental Office
The dental assistant is exposed to a wide variety of chemicals used for treatment procedures, cleaning of instruments and surfaces, disinfection and sterilization, laboratory procedures, and x-ray processing.
Potential damage targets: heart, kidney, liver, and lung tissues.
Results of exposure range from short-term discomfort (e.g., burns, rashes) to life-threatening conditions (e.g., cancer, sterility, organ failure).
Hazardous Chemicals: Definitions and Classifications
Hazardous chemicals are defined as any chemical that can cause a physical or health hazard.
A chemical is considered hazardous if it:
Can ignite (catch fire) .
Can react or explode when mixed with other substances.
Is corrosive.
Is toxic.
Hazardous Chemical Categories (Visual cues)
CORROSIVE MATERIALS
TOXIC CHEMICALS
FLAMMABLE SOLVENTS
Note: Copyright and source references pertain to textbook illustrations.
Exposure to Chemicals: Primary Routes
Three primary methods of exposure include:
Inhalation
Skin contact
Ingestion
Gases, vapors, and dusts of chemicals can cause direct damage to the lungs.
Acute and Chronic Chemical Toxicity
Acute chemical toxicity: Results from a high level of exposure over a short period.
Chronic chemical toxicity: Results from many repeated exposures, generally to lower levels, over a much longer time — months or years.
Hand Protection
When using chemical disinfectants, wear a utility-type glove made from a chemical-resistant material such as natural rubber, neoprene, or industrial-grade nitrile.
Latex gloves worn during patient care do not provide adequate protection when handling chemicals.
Eye Protection
Serious damage or blindness can result from chemical accidents.
Safety eyewear options vary; ideal goggles have soft vinyl flanges (rims) at the top and bottom and fit the face snugly.
Protective Clothing
When caustic or staining chemicals are used, wear a rubber or neoprene apron when mixing or pouring the chemical.
The Safety Data Sheet (SDS, formerly MSDS) for each product provides specific information regarding the need for additional personal protective equipment (PPE).
Inhalation Protection
Masks worn during patient care may or may not provide adequate protection when working with chemicals.
The proper face mask should be fluid-repellent and should provide respiratory protection.
Control of Chemical Spills
Accidents and spills should not be common occurrences.
Planning and practice in dealing with spills should minimize employee exposure to harmful chemicals.
Refer to the Safety Data Sheet (SDS) for the specific product for accurate information on how to manage spills.
Mercury Spill Kit
Should be available in all dental offices in which amalgam is used.
Exposure to even small amounts of mercury is very hazardous to health of dental personnel.
Mercury can be absorbed through the skin or inhaled as mercury vapors.
Acid Spill Emergency Cleanup Instructions (Acid Spill)
For a spill up to 1 liter (Not for use with hydrofluoric acid):
Protect
Absorbs
Neutralize
Cleanup
Steps referenced from Stepp CA, Woods M: Laboratory procedures for medical office personnel (1998).
Copyright © 2024, Elsevier Inc.
Eyewash Units
OSHA regulations require an eyewash unit in every place of employment where chemicals are used.
When turned on, eyewash irrigates the eyes with a soft, wide flow of water to bathe away contaminants without causing additional damage.
Employees must be trained in proper use of the eyewash station, and the unit should be inspected every to ensure functionality.
Eyewash Units (Images and Examples)
Visual references show different eyewash configurations (A and B) from lab safety materials.
Ventilation
Good ventilation is essential when dealing with any type of chemical.
Many dental offices have specialized exhaust systems in the laboratory, sterilization, and darkroom areas for fumes and dust.
General Precautions for Storing Chemicals
Store dental medications and chemicals in a dry, cool, dark place and away from direct sunlight.
Follow instructions on the product; avoid exposure to light.
Check expiration date; rotate inventory to use older materials first.
Removal of Empty Containers
Empty containers may still hold residues that can burn or explode.
Never fill an empty container with another substance because dangerous chemical reactions could occur.
Follow the label and SDS guidance for disposing of empty containers.
Disposal of Waste in the Dental Office
Dental offices use substances regulated under federal, state, or local environmental regulations.
Materials may affect wastewater treatment or bypass treatment into waterways.
Many states require hauling specific waste by licensed carriers.
Classification of Waste
General waste: nonhazardous, nonregulated waste discarded in covered containers.
Hazardous waste: ignitable, corrosive, reactive, toxic, or EPA-listed waste.
Contaminated waste: contact with blood or other body fluids; infectious or regulated waste.
Pathologic Waste and Sharps.
General Waste Management
Regular dental office waste should be recycled whenever possible (e.g., aluminum, glass, newspapers, corrugated fiber, office paper, mixed paper).
Handling Hazardous Waste
May include toxic chemicals, extracted teeth with amalgam restorations, and other toxic waste.
Dispose in accordance with local and state regulations.
Disinfectants
Small quantities of spent germicidal solutions containing or less of glutaraldehyde can usually be poured down the drain.
Check with local authorities on disposal methods for these chemicals.
Scrap Amalgam
Collect and store scrap amalgam in a designated, dry, airtight container.
Scrap amalgam not recycled must be managed as hazardous waste.
Recycled scrap amalgam container must be labeled with the dental office name, address, telephone, and the date collection started.
Photochemical Waste
Radiographic fixer: on-site treatment requires silver recovery systems.
Off-site treatment involves storing used fixer and contracting with a disposal company for pickup.
Radiographic developer: products with high or low pH are likely hazardous waste and must be managed per local regulations.
Lead Contamination
Lead foil is easily recyclable but cannot be disposed of in the regular garbage.
Exempt from regulation as hazardous waste when recycled as scrap metal, but must be recycled through a licensed recovery facility.
Handling Contaminated Waste
Should be placed in a lined trash receptacle with a properly fitted lid.
Empty contents daily or when full; in most states, dispose of with general waste.
Handling Infectious or Regulated Waste
Never dispose of infectious waste with general waste.
Types include blood/blood-soaked materials, pathologic waste (e.g., soft tissue, extracted teeth), and sharps.
Sharps must go in specialized “sharps” containers labeled with universal biohazard symbol.
Disposal of Medical Waste
Once contaminated waste leaves the office, disposal is regulated by the EPA and state/local laws.
Disposal manner is often determined by the weight of infectious materials.
The average dental practice is categorized as a “small producer” of infectious waste and disposal is regulated accordingly.
The dentist must maintain records of final disposal (how, when, where).
Pathologic Waste
Must be separated and collected for disposal in a container that is leak-proof, has a tight-fitting lid, labeled “pathologic waste – incineration only,” and collected by a medical waste company.
Handling Extracted Teeth
Dispose of extracted teeth as regulated medical waste unless returned to the patient.
If teeth are returned, standard disposal provisions no longer apply.
Do not dispose of extracted teeth containing amalgam in regulated medical waste destined for incineration.
Check state/local regulations for disposal of teeth containing amalgam.
Sharps (Infectious Waste)
OSHA, CDC, and EPA classify sharps as infectious waste.
Disposable sharps must be placed in a closable, leakproof, puncture-resistant container immediately after use.
Container must be labeled with the biohazard symbol and color-coded for easy identification.
State regulations differ on container pickup frequency.
Hazard Communication Program (OSHA)
OSHA issued the Hazard Communication Standard to ensure employees know the identity and hazards of chemicals in the workplace (Employee Right-to-Know).
Requires employers to implement a hazard communication program.
Major Changes to the Hazard Communication Standard (HCS)
Hazard classification: chemicals categorized to compare hazard severity within a hazard class; same category implies same label requirements and language.
Labels: all labels include a harmonized signal word, pictogram, and hazard statement for each hazard class/category.
Safety Data Sheets (SDS): now use a specified .
Chemical Inventory
A comprehensive list of every product used in the office is required.
When a new product with a hazardous chemical is added, it must be added to the chemical list, and the SDS must be placed in the SDS file.
The manufacturer/distributor should provide an updated SDS when appropriate.
Safety Data Sheets (SDS)
SDSs contain health and safety information about every chemical in the office.
They provide comprehensive technical information and are a resource for employees.
Describe: physical and chemical properties, health hazards, routes of exposure, precautions for safe handling and use, emergency and first-aid procedures, spill-control measures.
Labeling of Chemical Containers
Containers must be labeled to indicate contents and any associated hazards.
When a chemical is transferred to a different container, the new container must also be labeled.
No single universal labeling system is required; multiple approaches are possible.
Two key requirements:
The labeling system includes all required information.
All employees are trained to read and understand the label.
NFPA Hazard Labeling System
The National Fire Protection Association (NFPA) labeling system uses four diamonds (blue, red, yellow, white).
Each diamond contains a numeric rating from 0 to 4 for each category:
Health hazard (blue)
Flammability (red)
Reactivity (yellow)
Special hazards (white), e.g., OXY for oxidizers.
Exemptions to Labeling Requirements
Certain chemicals are exempt from labeling requirements, such as tobacco and tobacco products, wood and wood products, food, drugs, cosmetics, and alcoholic beverages sold and packaged for consumer use.