Toxicology Principles, Exposure Routes, and History Practice Questions

25 multiple-choice questions on Toxicology principles, exposure routes, and history for paramedic and EMT students, from Chapter 28 (Toxicology). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. A poison is best defined as any substance that:

   1. A. Is illegal to possess or sell without a valid prescription
   2. B. Harms body structure or function once it enters the body
   3. C. Produces dependence after repeated use over time
   4. D. Causes symptoms only when taken in very large doses
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   Answer: B. Harms body structure or function once it enters the body

   Toxicity depends on dose, route, and the patient, so even water or prescribed drugs can poison. Legality and dependence describe drugs of abuse, not toxicity itself.

2. The four routes by which a poison can enter the body are:

   1. A. Ingestion, inhalation, digestion, and excretion
   2. B. Injection, aspiration, filtration, and absorption
   3. C. Inhalation, secretion, ingestion, and circulation
   4. D. Ingestion, inhalation, injection, and absorption
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   Answer: D. Ingestion, inhalation, injection, and absorption

   Every toxic exposure enters by one of these four routes. Digestion and excretion are what happen after entry, not routes of exposure.

3. Which route of exposure usually produces the fastest systemic effects?

   1. A. Ingestion
   2. B. Skin absorption
   3. C. Inhalation
   4. D. Subcutaneous injection
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   Answer: C. Inhalation

   Inhaled toxins cross the huge alveolar surface and reach the arterial circulation within seconds. Ingested toxins must first be absorbed from the gut and pass through the liver, which delays onset.

4. The most common route of poisoning in the United States is:

   1. A. Ingestion
   2. B. Inhalation
   3. C. Injection
   4. D. Skin absorption
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   Answer: A. Ingestion

   Most poisonings, especially in children, are swallowed. Inhalation causes many of the deaths but is far less common overall.

5. Most unintentional poisonings in the United States occur in:

   1. A. Adolescents aged 13 to 18
   2. B. Adults older than 65 years
   3. C. Workers in industrial settings
   4. D. Children younger than 6 years
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   Answer: D. Children younger than 6 years

   Toddlers explore by putting objects in their mouths. Intentional overdoses are more common in adolescents and adults.

6. The national poison control phone number in the United States is:

   1. A. 1-800-273-8255
   2. B. 1-888-426-4435
   3. C. 1-800-222-1222
   4. D. 1-800-424-9300
   Show answer

   Answer: C. 1-800-222-1222

   Poison centers are staffed around the clock by toxicology specialists. 1-800-424-9300 is CHEMTREC, which gives hazmat product information, not patient management advice.

7. You are dispatched to a home where two family members are unconscious and a third has a headache. Your first action should be to:

   1. A. Suspect a toxic gas; stay out until the scene is safe
   2. B. Enter quickly and drag both patients to fresh air
   3. C. Open the windows and begin CPR on the sickest patient
   4. D. Ask the conscious patient what medications they take
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   Answer: A. Suspect a toxic gas; stay out until the scene is safe

   Several sick people in one enclosed space suggests carbon monoxide or another gas. Entering without protection risks making you the next patient, and rescue belongs to properly equipped crews.

8. A patient who has overdosed is the classic example of a scene where:

   1. A. Body substance isolation is not needed for the crew
   2. B. Your safety and the risk of violence come first
   3. C. The history is usually accurate and complete
   4. D. Transport is rarely needed if the patient is alert
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   Answer: B. Your safety and the risk of violence come first

   Intoxicated or suicidal patients can be combative, and drug scenes may hold needles, weapons, or chemicals. Overdose histories are often incomplete or deliberately false.

9. When obtaining a history from a poisoned patient, the key questions include:

   1. A. Why the patient took it and who supplied it
   2. B. Where the drug was bought and its price
   3. C. What, when, how much, and by what route
   4. D. Whether the patient has insurance or a regular doctor
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   Answer: C. What, when, how much, and by what route

   The substance, time, amount, and route guide treatment and antidote choice. Social details may matter later but do not drive acute management. Why the drug was taken and where it came from matter for safety and mental health follow-up, not for the first treatment decisions.

10. A teenager admits to taking 'a few' of her mother's pills 2 hours ago. You should:

    1. A. Bring the pill bottles to the hospital
    2. B. Accept her estimate and document it as a few pills
    3. C. Leave the bottles so the police can count them
    4. D. Induce vomiting before you begin transport
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    Answer: A. Bring the pill bottles to the hospital

    Patients often underestimate or hide how much they took, so the bottles allow the hospital to count remaining pills. Inducing vomiting is no longer recommended.

11. Syrup of ipecac is no longer recommended for poisoning because it:

    1. A. Is too expensive for most EMS agencies to keep stocked
    2. B. Delays other care and has not improved outcomes
    3. C. Works only for ingestions of liquid poisons
    4. D. Must be given intravenously to be effective
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    Answer: B. Delays other care and has not improved outcomes

    Ipecac-induced vomiting removes little poison, raises aspiration risk, and delays charcoal or antidotes. It is an oral syrup, so the IV option is simply false.

12. Why is the time of ingestion important to the receiving facility?

    1. A. It shows how many pills the patient actually swallowed
    2. B. It decides which hospital the patient must be taken to
    3. C. It reveals whether the overdose was intentional or accidental
    4. D. Some antidotes and levels depend on time since ingestion
    Show answer

    Answer: D. Some antidotes and levels depend on time since ingestion

    For example, the acetaminophen nomogram requires a level plotted against hours since ingestion, and charcoal works best within 1 hour. The time of ingestion says nothing about how many pills were taken or whether the overdose was intentional.

13. A patient's absorption of a toxin is generally slowed when the toxin:

    1. A. Is inhaled as a gas or a fine aerosol mist
    2. B. Is injected directly into a peripheral vein
    3. C. Is a sustained-release or enteric-coated tablet
    4. D. Is a liquid taken on a completely empty stomach
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    Answer: C. Is a sustained-release or enteric-coated tablet

    Extended-release formulations release drug over many hours, so symptoms may be delayed and prolonged. Inhaled, IV, and liquid exposures are absorbed quickly.

14. A 35-year-old man is found with an empty pill bottle and is alert with normal vitals. He says he took the pills 20 minutes ago. The correct approach is to:

    1. A. Release him because his vital signs are normal
    2. B. Wait 30 minutes on scene to see if symptoms develop
    3. C. Have him sign a refusal since he is alert now
    4. D. Treat it as a possible serious overdose; transport
    Show answer

    Answer: D. Treat it as a possible serious overdose; transport

    Many toxins have delayed onset, so a well-appearing patient early after ingestion can deteriorate. An intentional ingestion also implies suicide risk and lack of capacity to refuse.

15. The term 'toxidrome' refers to:

    1. A. Signs and symptoms typical of a class of poisons
    2. B. A laboratory test that measures drug blood levels
    3. C. The list of antidotes carried on an ambulance
    4. D. A poison that affects more than one organ system
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    Answer: A. Signs and symptoms typical of a class of poisons

    Recognizing a toxidrome lets you treat by drug class even when the exact substance is unknown. Blood levels are hospital tests, and multiple organ effects do not define a toxidrome.

16. Which finding at the scene most strongly suggests an intentional ingestion?

    1. A. A child-resistant cap left on the counter
    2. B. A suicide note found next to the patient
    3. C. A household cleaner stored under the sink
    4. D. A bottle of vitamins in the kitchen cabinet
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    Answer: B. A suicide note found next to the patient

    A note or statements about self-harm indicate intent and require a suicide risk assessment and transport. Ordinary household products are expected findings.

17. A worker has a dry chemical powder on his arms. Before flushing with water, you should:

    1. A. Neutralize it with a weak acid or base
    2. B. Cover the area with a moist occlusive dressing
    3. C. Apply activated charcoal paste to the skin
    4. D. Brush off as much of the powder as possible
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    Answer: D. Brush off as much of the powder as possible

    Some dry chemicals such as lime react with water, so brushing first reduces the load before copious irrigation. Neutralizing agents create heat and worsen burns.

18. Absorption of a toxin through the skin is increased by:

    1. A. Thick calluses and a water-soluble toxin
    2. B. Cool skin and a short exposure time
    3. C. Broken skin and a lipid-soluble toxin
    4. D. Dry skin and a large molecular size
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    Answer: C. Broken skin and a lipid-soluble toxin

    Organophosphates and hydrocarbons are lipid soluble and cross intact skin, and abrasions remove the barrier further. Thick skin and short contact reduce absorption.

19. An injected toxin is most often encountered in EMS as a result of:

    1. A. Illicit drug use or an envenomation
    2. B. Ingesting a household cleaning product
    3. C. Inhaling smoke at a structure fire
    4. D. Splashing a chemical onto the eyes
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    Answer: A. Illicit drug use or an envenomation

    Injection includes IV drug use, needles, and bites or stings. The other choices describe ingestion, inhalation, and absorption.

20. Poison control centers can help EMS providers by:

    1. A. Dispatching a hazmat team directly to the scene
    2. B. Advising on a product's toxicity and treatment
    3. C. Authorizing transport to a specialty hospital
    4. D. Replacing the need for online medical control
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    Answer: B. Advising on a product's toxicity and treatment

    Poison centers have product databases and toxicologists for management advice. They do not dispatch resources, and you still follow medical direction and protocols.

21. Which patient has the highest risk of an intentional overdose?

    1. A. A 2-year-old who got into a cabinet
    2. B. A 30-year-old farmer spraying crops
    3. C. A recently divorced, unemployed 45-year-old man
    4. D. A 70-year-old who confused two similar pill bottles
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    Answer: C. A recently divorced, unemployed 45-year-old man

    Major losses and life stressors raise suicide risk. The other patients illustrate accidental pediatric, occupational, and medication-error exposures.

22. Older adults are at higher risk for unintentional poisoning mainly because of:

    1. A. Greater curiosity about unfamiliar household products
    2. B. More frequent exposure to industrial chemicals at work
    3. C. A tendency to underreport alcohol use to their doctors
    4. D. Multiple medications and slower drug clearance
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    Answer: D. Multiple medications and slower drug clearance

    Polypharmacy, reduced kidney and liver function, and confusion lead to medication errors and drug interactions. Curiosity drives pediatric poisonings, not geriatric ones.

23. The physical exam of a poisoned patient should specifically include:

    1. A. Pupils, skin, breath odor, and mental status
    2. B. Visual acuity, hearing, and grip strength
    3. C. Reflexes, gait, and two-point discrimination
    4. D. Hair texture, nail beds, and dentition
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    Answer: A. Pupils, skin, breath odor, and mental status

    Pupil size, sweating, skin color, odors, and mental status are the clues that point to a toxidrome. Fine neurologic testing adds little in the field.

24. A substance abuser who uses a drug repeatedly and needs larger doses for the same effect has developed:

    1. A. Withdrawal
    2. B. Tolerance
    3. C. Addiction
    4. D. Habituation
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    Answer: B. Tolerance

    Tolerance means a higher dose is needed for the same effect. Addiction is compulsive use despite harm, and withdrawal is the syndrome when the drug is stopped.

25. A patient who develops physical signs such as tremor and sweating when a drug is stopped is showing:

    1. A. Drug tolerance
    2. B. Psychological craving
    3. C. An idiosyncratic reaction
    4. D. Physical dependence
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    Answer: D. Physical dependence

    Physical dependence is defined by a withdrawal syndrome on stopping the drug. Tolerance can accompany it but describes the dose-response change, not the withdrawal signs.