Practice Test Geeks(CPA) Certified Pesticide Applicator Practice Test
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Pesticide Toxicology and Mode of Action Flashcards

7 cards from real CPA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What term describes the dose of a pesticide required to kill 50% of a test animal population under specified conditions?

    Answer: LD50

    LD50 (Lethal Dose 50) is the standard measure of acute oral or dermal toxicity, expressed in mg of pesticide per kg of body weight.

  2. Which pesticide class inhibits acetylcholinesterase, preventing the breakdown of acetylcholine and causing continuous nerve stimulation?

    Answer: Organophosphates

    Organophosphates and carbamates inhibit acetylcholinesterase, leading to acetylcholine accumulation and overstimulation of the nervous system.

  3. What is the primary mode of action of pyrethroid insecticides such as permethrin and cypermethrin?

    Answer: Block sodium channel inactivation

    Pyrethroids keep voltage-gated sodium channels open, causing prolonged nerve depolarization and repetitive nerve firing in insects.

  4. Which type of toxicity results from a single or short-term exposure to a high dose of a pesticide?

    Answer: Acute toxicity

    Acute toxicity refers to adverse effects that occur from a single dose or short-term exposure, often appearing within 24–96 hours.

  5. A pesticide has an oral LD50 of 5 mg/kg body weight. How would this pesticide be classified under EPA toxicity categories?

    Answer: Highly toxic (Category I)

    Category I (Highly Toxic) includes pesticides with oral LD50 values less than 50 mg/kg, which carry the DANGER signal word on the label.

  6. For most pesticide applicators during routine fieldwork, which route of pesticide exposure is generally considered the most significant?

    Answer: Dermal contact

    Dermal exposure accounts for the majority of pesticide exposure for applicators because skin contact occurs throughout mixing, loading, and applying operations.

  7. What term describes the potential of a pesticide to cause cancer in exposed organisms?

    Answer: Carcinogenicity

    Carcinogenicity refers to a substance's ability to cause cancer, and EPA evaluates this through weight-of-evidence classifications for pesticide registration.