Toxicologic Management of Specific Hazmat Agents Practice Questions

25 multiple-choice questions on Toxicologic management of specific hazmat agents for paramedic and EMT students, from Chapter 50 (Hazardous Materials). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A lab worker spilled phenol (carbolic acid) on his forearm. The burn looks white but he says it barely hurts. The lack of pain is explained by phenol's:

   1. A. Poor skin penetration
   2. B. Rapid evaporation from the skin surface
   3. C. Neutralization by sweat on the skin
   4. D. Local anesthetic effect
   Show answer

   Answer: D. Local anesthetic effect

   Phenol numbs the skin as it is absorbed, so a serious burn and systemic toxicity, including dysrhythmias and seizures, can occur with little pain. It penetrates skin well, not poorly. It does not evaporate fast enough to spare the skin, and sweat does not neutralize it. It is removed with polyethylene glycol, if available, or large volumes of water.

2. A soldier at a training range has burning particles of white phosphorus embedded in his leg. You should:

   1. A. Keep it wet with saline-soaked dressings
   2. B. Let the particles burn out, then apply a dry dressing
   3. C. Brush the particles off dry and leave the area open
   4. D. Cover the wound with an oil-based ointment and wrap
   Show answer

   Answer: A. Keep it wet with saline-soaked dressings

   White phosphorus ignites on contact with air, so the area must stay wet or submerged until the particles are removed at the hospital. Dry dressings let it reignite, and oily ointments can increase absorption.

3. A farmer is sprayed with liquid anhydrous ammonia when a hose on a nurse tank bursts. His sleeve is frozen to his white, stiff forearm. The frozen sleeve should be:

   1. A. Thawed with lukewarm water, then removed
   2. B. Pulled off at once to stop the burn
   3. C. Left on until he reaches the hospital
   4. D. Cut off, then the skin warmed with heat packs
   Show answer

   Answer: A. Thawed with lukewarm water, then removed

   Liquid anhydrous ammonia freezes tissue as it boils off and forms a strong alkali on moist skin, so the injury is both a cold injury and an alkali burn. Clothing frozen to the skin is thawed with water and then removed, and the area is flushed with large volumes of water for a long time, because soaked fabric keeps feeding ammonia to the skin. Pulling it off while frozen tears the injured skin. Leaving it on until the hospital lets the alkali keep burning. Cutting the sleeve off dry still pulls on the frozen tissue, and dry heat packs can burn numb, frozen skin and do nothing to remove the ammonia.

4. Ammonia is highly water-soluble. A worker exposed to a brief release of ammonia gas is most likely to have:

   1. A. Delayed lung injury with no early warning
   2. B. Damage centered in the small air sacs
   3. C. Symptoms that start after about 24 hours
   4. D. Immediate eye, nose, and throat burning
   Show answer

   Answer: D. Immediate eye, nose, and throat burning

   Highly water-soluble gases dissolve in the moisture of the eyes and upper airway, so they irritate at once and usually drive people away. Poorly soluble gases, such as phosgene, pass to the alveoli with little warning.

5. A woman cleaning a bathroom mixed bleach with an ammonia-based cleaner. She is coughing with burning eyes. The gas produced was most likely:

   1. A. Phosgene
   2. B. Hydrogen sulfide
   3. C. Chloramine
   4. D. Methane
   Show answer

   Answer: C. Chloramine

   Bleach (sodium hypochlorite) mixed with ammonia releases chloramine gases, which irritate the eyes and airway. Mixing bleach with an acid cleaner releases chlorine gas instead.

6. A 34-year-old pool worker has wheezing and a cough after a chlorine release. He is alert with an SpO2 of 92%. Prehospital management should include:

   1. A. Oxygen and IV furosemide for the lungs
   2. B. Humidified oxygen and a bronchodilator
   3. C. Supine positioning and a fluid bolus
   4. D. Oxygen and rapid sequence intubation
   Show answer

   Answer: B. Humidified oxygen and a bronchodilator

   Chlorine injures the airway, causing bronchospasm and irritation; humidified oxygen and a bronchodilator such as albuterol ease symptoms. Some protocols add nebulized sodium bicarbonate. Lying flat worsens his breathing. Furosemide does not treat chemical lung injury and can drop the blood pressure, and an alert patient who is protecting his airway with an SpO2 of 92% does not need immediate rapid sequence intubation.

7. A farmer exposed to a pesticide hands you the jug. Its label carries the signal word 'CAUTION.' Compared with a product labeled 'DANGER-POISON,' this one is:

   1. A. More toxic; CAUTION is the highest warning
   2. B. Equally toxic; the words vary by maker
   3. C. Less toxic; CAUTION is the lowest level
   4. D. Not toxic; CAUTION refers to fire risk
   Show answer

   Answer: C. Less toxic; CAUTION is the lowest level

   EPA pesticide labels use signal words tied to acute toxicity categories (40 CFR 156.64). DANGER with POISON and a skull and crossbones marks Category I, the most toxic by mouth, skin, or inhalation (DANGER alone can mark a product corrosive to skin or eyes); WARNING marks moderately toxic Category II; and CAUTION marks the least toxic, Categories III and IV. A CAUTION product can still make him ill, so the label's first-aid section and poison control guide care. CAUTION is the weakest signal word, not the strongest. The words are set by federal rule, not chosen by each maker. They describe toxicity, not fire risk.

8. A welder was working near a tank of chlorinated degreasing solvent and noticed a smell like freshly mown hay. He feels fine. The gas he likely inhaled is:

   1. A. Chlorine
   2. B. Phosgene
   3. C. Ammonia
   4. D. Cyanide
   Show answer

   Answer: B. Phosgene

   Heating chlorinated solvents, as in welding near a degreaser, can form phosgene, which smells like freshly mown hay. Feeling fine is not reassuring: he needs evaluation and observation.

9. A worker collapsed after inhaling fumes from a halogenated degreasing solvent in a closed tank. He is in sinus tachycardia with frequent PVCs. Because these solvents sensitize the heart, you should:

   1. A. Give epinephrine early to support his blood pressure
   2. B. Have him walk to the ambulance to keep him alert
   3. C. Give albuterol to prevent bronchospasm from the fumes
   4. D. Avoid catecholamines if possible and keep him calm
   Show answer

   Answer: D. Avoid catecholamines if possible and keep him calm

   Halogenated hydrocarbons make the myocardium sensitive to catecholamines, so stress, exertion, and drugs such as epinephrine or albuterol can trigger VF. Keep the patient calm and still, and use catecholamines only if clearly needed.

10. A man used a methylene chloride paint stripper in a closed garage for several hours. Hours later, he has a headache and nausea. This solvent is dangerous because it:

    1. A. Is metabolized into carbon monoxide
    2. B. Is converted by the liver into cyanide
    3. C. Causes delayed liver failure within hours
    4. D. Releases phosgene at room temperature
    Show answer

    Answer: A. Is metabolized into carbon monoxide

    Methylene chloride is metabolized to carbon monoxide, so carboxyhemoglobin can keep rising after exposure ends and last longer than in direct CO exposure. He needs high-flow oxygen and a CO level.

11. A driver was trapped for an hour in a crash with his legs soaked in gasoline. His skin is red and blistered. Prolonged skin contact with gasoline can cause:

    1. A. Chemical burns, even full-thickness
    2. B. Mild irritation that resolves quickly
    3. C. Frostbite from rapid evaporation
    4. D. Methemoglobinemia from skin absorption
    Show answer

    Answer: A. Chemical burns, even full-thickness

    Hydrocarbons dissolve skin oils and, with long contact, can cause partial- and full-thickness chemical burns and systemic absorption. Soaked clothing should be removed and the skin washed with soap and water.

12. A worker has had years of low-level exposure to benzene at a refinery. The long-term effect most associated with benzene is:

    1. A. Kidney stones and gouty arthritis
    2. B. Hearing loss and tinnitus
    3. C. Aplastic anemia and leukemia
    4. D. Peripheral neuropathy
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    Answer: C. Aplastic anemia and leukemia

    Benzene is toxic to the bone marrow, and chronic exposure causes aplastic anemia and leukemia. Peripheral neuropathy is linked to other solvents, such as n-hexane.

13. Hours after breathing a garlic-smelling gas (arsine) at a semiconductor plant, a worker has abdominal pain, dark red urine, and yellow eyes. Arsine's main toxic effect is:

    1. A. Formation of methemoglobin in the blood
    2. B. Massive breakdown of red blood cells
    3. C. Direct burns to the upper airway
    4. D. Binding hemoglobin in place of oxygen
    Show answer

    Answer: B. Massive breakdown of red blood cells

    Arsine, a gas used in the semiconductor industry and released when acids contact metals containing arsenic, destroys red blood cells. Hemolysis causes abdominal pain, dark red or brown urine from free hemoglobin, jaundice within a day or two, and acute kidney failure, often 2 to 24 hours after the exposure. There is no specific antidote; care is supportive, with attention to kidney function and possible transfusion. Methemoglobinemia makes the blood chocolate brown and causes cyanosis with a low SpO2, not jaundice and red urine. Arsine is not a strong airway irritant, which is why workers may not notice the exposure. Binding hemoglobin in place of oxygen is the mechanism of carbon monoxide.

14. At an electroplating shop, a worker poured an acid cleaner into a tank of cyanide salts and collapsed. The most likely toxic exposure is:

    1. A. Chlorine gas from the acid and the metal tank
    2. B. Hydrogen sulfide from the acid and the plating
    3. C. Phosgene gas from the acid and the warm tank
    4. D. Hydrogen cyanide from acid and cyanide salts
    Show answer

    Answer: D. Hydrogen cyanide from acid and cyanide salts

    Cyanide salts used in electroplating, jewelry work, and mining release hydrogen cyanide gas when mixed with acid. The area must be treated as a hot zone until it is cleared.

15. A man swallowed potassium cyanide and is unconscious with slow, shallow breathing. When providing ventilation, you should:

    1. A. Give mouth-to-mouth breaths to save time
    2. B. Withhold ventilation until decon is done
    3. C. Induce vomiting before starting ventilation
    4. D. Use a BVM and avoid mouth-to-mouth contact
    Show answer

    Answer: D. Use a BVM and avoid mouth-to-mouth contact

    Cyanide salts in the stomach can release hydrogen cyanide gas, and vomitus or exhaled air may expose rescuers, so a BVM with oxygen is used. Vomiting is not induced, and ventilation should not be delayed.

16. A decontaminated worker exposed to an unidentified industrial chemical is wheezing and anxious, with HR 104, normal pupils, no excess secretions, and SpO2 95%. Poison control is still working to identify the product. Your care should focus on:

    1. A. Giving atropine in case it is a pesticide
    2. B. Giving hydroxocobalamin in case of cyanide
    3. C. Treating symptoms and supporting the ABCs
    4. D. Giving charcoal in case he swallowed some
    Show answer

    Answer: C. Treating symptoms and supporting the ABCs

    Most hazmat exposures have no specific antidote, so after decon the care is supportive: oxygen as needed, a bronchodilator for the wheezing, monitoring, and transport, with poison control and the SDS guiding further treatment once the product is known. Atropine is given for cholinergic signs such as copious secretions, bradycardia, and pinpoint pupils; giving it without them can cause tachycardia and anticholinergic toxicity. Hydroxocobalamin is reserved for suspected cyanide poisoning with serious signs such as altered mental status, hypotension, or collapse, which he does not have. Activated charcoal has no role in an inhalation or skin exposure and adds aspiration risk.

17. A lab technician dropped a flask of liquid (elemental) mercury, and beads are scattered across a warm floor. The main health hazard to people in the room is:

    1. A. Inhaling the mercury vapor
    2. B. Absorbing it through intact skin
    3. C. Swallowing beads off the hands
    4. D. Touching the beads with gloves
    Show answer

    Answer: A. Inhaling the mercury vapor

    Elemental mercury vaporizes at room temperature, more so on warm surfaces, and inhaled vapor is well absorbed and toxic to the lungs, kidneys, and nervous system. Skin absorption and swallowed liquid mercury are poorly absorbed, which is why vapor is the main concern.

18. You are called to a parked car with the windows closed. A sign taped inside reads 'Toxic gas, do not open,' and a bucket of liquid is on the floor. You should:

    1. A. Open the doors quickly to air out the car
    2. B. Stay back, keep others away, call hazmat
    3. C. Break a window to reach the patient fast
    4. D. Hold your breath and pull the person out
    Show answer

    Answer: B. Stay back, keep others away, call hazmat

    This is a classic detergent (chemical) suicide, in which household chemicals are mixed to release a toxic gas such as hydrogen sulfide. Opening the car releases a concentrated gas that can overcome rescuers; responders need SCBA and hazmat support.

19. Hydrogen sulfide is toxic mainly because it:

    1. A. Blocks cytochrome oxidase in mitochondria
    2. B. Binds hemoglobin more tightly than oxygen
    3. C. Converts hemoglobin into methemoglobin
    4. D. Displaces oxygen from the air it fills
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    Answer: A. Blocks cytochrome oxidase in mitochondria

    Hydrogen sulfide blocks cytochrome oxidase in the mitochondria, halting aerobic metabolism much as cyanide does. Binding hemoglobin more tightly than oxygen is the mechanism of carbon monoxide. Converting hemoglobin to methemoglobin describes nitrites, aniline, and benzocaine. Displacing oxygen from the air is how simple asphyxiants such as nitrogen work; H2S is toxic at levels far too low to lower the oxygen concentration.

20. A crop-dusting worker has copious secretions, vomiting, and muscle twitching after a pesticide spill, but his heart rate is 128 and his pupils are midsize. You should:

    1. A. Rule out organophosphates by the heart rate
    2. B. Still suspect organophosphate poisoning
    3. C. Suspect a sympathomimetic overdose instead
    4. D. Treat for anxiety and check his blood sugar
    Show answer

    Answer: B. Still suspect organophosphate poisoning

    Organophosphates also stimulate nicotinic receptors, which can cause tachycardia, hypertension, fasciculations, and normal or dilated pupils. Copious secretions and twitching after a pesticide spill strongly suggest the diagnosis despite the fast pulse.

21. Compared with organophosphates, carbamate insecticides usually cause a shorter illness because carbamates:

    1. A. Do not affect acetylcholinesterase
    2. B. Are not absorbed through intact skin
    3. C. Cause effects after a delay of days
    4. D. Bind acetylcholinesterase reversibly
    Show answer

    Answer: D. Bind acetylcholinesterase reversibly

    Carbamates inhibit acetylcholinesterase, but the bond breaks down on its own within hours, so toxicity is usually shorter and does not 'age' as it does with organophosphates. They can still cause severe cholinergic toxicity.

22. A worker with a hydrofluoric acid burn to both hands develops a prolonged QT interval on the monitor, then ventricular fibrillation. Along with defibrillation, he needs:

    1. A. IV sodium bicarbonate for acid in the blood
    2. B. IV lidocaine to suppress the dysrhythmia
    3. C. IV calcium for fluoride-caused hypocalcemia
    4. D. IV glucose and insulin to lower potassium
    Show answer

    Answer: C. IV calcium for fluoride-caused hypocalcemia

    Fluoride ions bind calcium and magnesium, causing life-threatening hypocalcemia, hypomagnesemia, and hyperkalemia that lead to QT prolongation and VF. Large doses of IV calcium are the specific treatment; magnesium may also be needed but does not correct the calcium.

23. A woman used a wheel cleaner containing dilute hydrofluoric acid without gloves. Her hands looked normal at first, but they became very painful that night. This delay is typical because dilute HF:

    1. A. Is inactive until it is diluted by sweat
    2. B. Is harmless unless it is swallowed whole
    3. C. Can take hours to cause pain and injury
    4. D. Acts at once like a strong mineral acid
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    Answer: C. Can take hours to cause pain and injury

    Concentrated HF causes immediate pain, but dilute solutions, such as some rust removers and wheel cleaners, can penetrate silently and cause pain and deep injury hours later. Any HF contact needs treatment even if the skin looks normal.

24. A worker collapsed in a tank that had been purged with nitrogen. Nitrogen causes harm in this setting by:

    1. A. Displacing oxygen from the air
    2. B. Blocking oxygen use in the mitochondria
    3. C. Binding hemoglobin
    4. D. Burning the airway as a strong irritant
    Show answer

    Answer: A. Displacing oxygen from the air

    Simple asphyxiants, such as nitrogen, argon, methane, and carbon dioxide, are not toxic themselves but displace oxygen. Chemical asphyxiants, such as cyanide and carbon monoxide, interfere with oxygen transport or use.

25. A farmworker drank a mouthful of paraquat herbicide. He is alert with an SpO2 of 96% on room air. Regarding oxygen, you should:

    1. A. Give high-flow oxygen by nonrebreather at once
    2. B. Give oxygen only if SpO2 falls below about 90%
    3. C. Give oxygen by nasal cannula at 6 L/min now
    4. D. Give oxygen to keep his SpO2 at 100%
    Show answer

    Answer: B. Give oxygen only if SpO2 falls below about 90%

    Paraquat generates free radicals in the lungs, and supplemental oxygen speeds lung injury, so oxygen is withheld unless the patient is hypoxic. This is one of the few poisonings in which high-flow oxygen is harmful.