Occupational Health and Applied Science practice questions

Answer: D) Deformation per unit length

• AIncorrect. That's power.
• BIncorrect. That's work.
• CIncorrect. That's density.
• DCorrect. It's dimensionless.

Answer: C) Force times distance moved

• AIncorrect. That's pressure or stress.
• BIncorrect. That's density.
• CCorrect. It's measured in joules or foot-pounds.
• DIncorrect. That's speed.

Answer: B) Thermal comfort conditions for building occupants

• AIncorrect. That's NFPA 13.
• BCorrect. It considers temperature, humidity and air speed.
• CIncorrect. That's NFPA 70E.
• DIncorrect. That's RCRA.

Answer: C) New cases in a population over a set period

• AIncorrect. That isn't incidence.
• BIncorrect. That's prevalence.
• CCorrect. Prevalence counts existing cases.
• DIncorrect. That isn't incidence.

Answer: C) Smaller than about 4 micrometers

• AIncorrect. Respirable particles are tiny.
• BIncorrect. Those settle quickly.
• CCorrect. Larger particles deposit in the upper airways.
• DIncorrect. They're particles.

Answer: B) A dose exists below which no adverse effect is expected because the body can tolerate it

The threshold concept assumes there is a dose below which no adverse effect is expected, which is the basis for most health-based exposure limits. Carcinogens are treated as having no safe level of exposure.

• AIncorrect. This describes a linear no-threshold model, the kind of assumption behind NIOSH's view that there is no safe level of exposure to a carcinogen. It is the opposite of the threshold concept.
• BCorrect. The threshold concept assumes the body's defense and repair capacity can handle doses below some level without adverse effect. It is not applied to carcinogens, for which NIOSH states there is no safe level of exposure.
• CIncorrect. The threshold concept is based on dose-response: effects depend on the dose. Duration matters only because it contributes to the total dose.
• DIncorrect. The LD50 is the dose that kills half of a test population. Non-lethal adverse effects appear at doses far below it, so it is not the threshold for harm.

Answer: B) Combined exposure may still harm hearing, so audiometric testing is worth considering.

Styrene and other solvents are ototoxic, and together with noise they can cause hearing loss even below the PELs. OSHA/NIOSH recommend assessing and controlling exposure and considering audiometric testing.

• AIncorrect. The OSHA/NIOSH bulletin warns that ototoxic chemicals and noise can act together and cause hearing loss even when each exposure is below its PEL.
• BCorrect. Styrene is listed as an ototoxic solvent, and its effect can be worsened by noise. The guidance says audiometric testing and exposure controls may prevent hearing loss even when noise is below the action level and the chemical is below its PEL.
• CIncorrect. The bulletin lists solvents such as styrene, toluene and xylene as an ototoxicant class alongside metals and asphyxiants. Styrene's effect on hearing has to be evaluated together with the noise.
• DIncorrect. Ototoxic chemicals reach the inner ear through the body, for example by inhalation or skin absorption, not as sound. Hearing protectors reduce only the noise part of the exposure, so chemical exposure must also be controlled.

Answer: B) Antagonistic

• AIncorrect. That's the sum.
• BCorrect. Antidotes often work this way.
• CIncorrect. That's amplified.
• DIncorrect. That's buildup over time.

Answer: D) Hearing

• AIncorrect. That's nephrotoxic.
• BIncorrect. That's oculotoxic.
• CIncorrect. That's hepatotoxic.
• DCorrect. Some solvents and metals are ototoxic.

Answer: A) HCV has no vaccine, so follow-up relies on testing and, if infection develops, antiviral treatment that cures most patients

Hepatitis B can be prevented with a vaccine that employers must offer to workers with occupational exposure. Hepatitis C has no vaccine, so managing an exposure depends on post-exposure testing and highly effective curative treatment.

• ACorrect. CDC states there is no vaccine for hepatitis C, and that 8–12 weeks of oral medication cures more than 95% of patients. Follow-up therefore depends on testing and treatment, not on immunization.
• BIncorrect. 29 CFR 1910.1030(f) requires employers to offer the hepatitis B vaccine. There is no HCV vaccine to offer.
• CIncorrect. CDC says HCV spreads when infected blood, even in microscopic amounts, enters another person's body. It does not spread through food or water.
• DIncorrect. No HCV vaccine exists. Also, the bloodborne pathogens standard requires a confidential medical evaluation and follow-up after any exposure incident, including testing of the source and the employee.