Preparing the practice

Correct answer: A. Human papillomavirus vaccine

• A. Correct, and this is the exception. HPV vaccination is recommended on the basis of age, routinely through 26 years with shared decision making to 45, not because someone works in healthcare. It is not an occupational requirement.
• B. Hepatitis B vaccination with post-vaccination serologic testing is the cornerstone occupational vaccine for anyone with reasonably anticipated exposure to blood.
• C. Varicella vaccine, marketed as Varivax, is recommended for healthcare personnel without evidence of immunity, because a susceptible worker exposed to chickenpox or shingles can transmit infection to vulnerable patients.
• D. MMR is recommended for personnel lacking documented immunity. Measles and mumps outbreaks in healthcare settings are precisely why this is required.

Note: The recall listed an 'HIV vaccine' among the options. No licensed HIV vaccine exists, so it is not a real answer choice. The occupational core set is hepatitis B, influenza, MMR, varicella and Tdap, with meningococcal for microbiologists.

Correct answer: C. Administrative control

• A. Engineering controls are physical modifications that isolate people from the hazard, such as high-volume evacuation, sharps containers with engineered protections, ventilation and physical barriers.
• B. PPE is the least effective tier because it protects only the wearer and only when correctly selected, fitted and used.
• C. Correct. Teledentistry changes how and when work is performed and who is present. Policies, scheduling and work practices are administrative controls, which sit in the lower-middle of the hierarchy because they depend on consistent human compliance.
• D. Elimination physically removes the hazard altogether and sits at the top of the hierarchy.

Correct answer: A. Personal protective equipment

• A. Correct. A respirator is worn on the body and is therefore PPE, the bottom tier. It protects only the individual wearing it, requires annual fit testing, a seal check at every use and correct doffing, and fails silently if any of those steps lapse.
• B. Engineering controls act on the environment rather than the person, for example a high-volume evacuator, a rubber dam or negative pressure ventilation.
• C. Administrative controls are policies and procedures such as screening, scheduling and training.
• D. Substitution means replacing a hazardous material or process with a safer one, for example using a hand instrument instead of an ultrasonic scaler to cut aerosol.

Correct answer: A. Vaccination of staff against a specific pathogen

• A. Correct as this question is keyed. Vaccination removes susceptibility to the specific pathogen entirely, so for that organism the hazard ceases to exist for the vaccinated person. It requires no ongoing compliance once complete.
• B. A rubber dam is an engineering control; it physically isolates the operative field and substantially reduces aerosol.
• C. Pre-appointment screening is an administrative control, a policy about who is seen and when.
• D. A face shield is PPE, the least effective tier.

Note: Strictly, classic occupational hygiene places vaccination among administrative or health-based controls, since elimination normally means physically removing the hazard from the workplace. Dental infection control sources commonly teach it as elimination because it eliminates host susceptibility, and that is the keyed answer here. Worth knowing both framings.

Correct answer: B. Monthly testing is sufficient for a routine sterilizer

• A. This is true. Any repair, relocation, or misuse warrants testing, conventionally three consecutive empty-chamber tests before returning the unit to service.
• B. Correct, and this is the exception. Monthly is not adequate. CDC guidance calls for biological monitoring at least weekly, so that a sterilizer failure is caught within days rather than weeks of instrument use.
• C. This is true. Loads containing implantable devices should carry a biological indicator, and the device should be quarantined until the result is known.
• D. This is true and is the accepted standard: at least weekly biological monitoring with an appropriate spore preparation.

Correct answer: D. A used scalpel blade

• A. A saliva ejector tip is general waste. It is discarded in the ordinary waste stream unless it is saturated with blood.
• B. A cotton roll with a trace of blood is general waste. The threshold for regulated soft waste is saturation or dripping, or the capacity to release blood when compressed.
• C. Packaging is ordinary waste and carries no contamination.
• D. Correct. Contaminated sharps are regulated waste without qualification and go straight into a rigid, leak-resistant, labelled sharps container. Scalpel blades, needles, endodontic files, burs, orthodontic wire and broken glass all belong there.

Correct answer: B. Broken glass from a contaminated container

• A. A disposable bib is general waste unless it is saturated with blood.
• B. Correct. Contaminated broken glass carries both a biological and a sharps hazard, so it is placed in a rigid sharps container and never swept by hand or dropped into ordinary waste. It should be picked up with forceps or a brush and pan.
• C. A disinfected impression tray is not waste at all if it is reusable, and a disposable one is general waste.
• D. Charts carry a confidentiality obligation and are shredded, but they are not biohazardous.

Note: The recall's alternative option was a used anaesthetic carpule. A carpule is a sharps-container item because it is glass and may have residual blood, so both options in the original wording point to the same underlying rule: contaminated glass goes in the sharps container.

Correct answer: D. Mycobacterium tuberculosis

• A. HIV is bloodborne, with a transmission risk of about 0.3 percent after percutaneous exposure to infected blood.
• B. Hepatitis B is the most transmissible of the bloodborne pathogens in occupational exposure, with a risk after a percutaneous injury from an e-antigen positive source that can approach 30 percent.
• C. Hepatitis C is bloodborne, with a transmission risk of roughly 1.8 percent after percutaneous exposure.
• D. Correct, and this is the exception. Tuberculosis is transmitted by the airborne route through droplet nuclei that stay suspended for hours. It requires an N95 respirator and an airborne infection isolation room, not the standard precautions used for blood.

Correct answer: B. Shelter in place indoors and await instructions

• A. Opening windows draws the contaminated air inside and defeats the purpose of sheltering.
• B. Correct. When an airborne hazard is outside and its nature is unknown, the building shell is protection. Shelter in place: remain indoors, close windows and doors, shut down systems that draw in outside air, and follow official instructions.
• C. Evacuating moves people into the plume. Evacuation is the answer when the hazard is inside, as in a fire or an internal spill.
• D. Sending someone out to investigate deliberately exposes a person to an unidentified hazard and is never correct.

Correct answer: B. Stay as low as possible while moving away from the spill

• A. Recirculating the air spreads the vapour through the whole building. Ventilation should exhaust to the outside, and only if the safety data sheet supports it.
• B. Correct. Most hazardous vapours are heavier than air and settle, so the breathable air is nearest the floor. Staying low while evacuating the immediate area limits inhalation. Then isolate the area, consult the safety data sheet and use the appropriate spill kit.
• C. A damp cloth is not respiratory protection against chemical vapour, and continuing treatment keeps both patient and operator in the hazard.
• D. Water can react violently with some chemicals, and it spreads the spill and creates contaminated runoff. The safety data sheet dictates the neutralising or absorbing agent.