Hazardous Materials and Toxicology Flashcards

What is the fundamental principle of toxicology attributed to Paracelsus?

Answer: The dose makes the poison — all substances can be toxic at a sufficient dose

Paracelsus established the foundational toxicology principle that the dose determines whether a substance is toxic — virtually any substance can cause harm at a sufficient dose, and many toxic substances are harmless at low exposures.

What is a 'dose-response relationship' in toxicology?

Answer: The relationship between the amount of a substance a person is exposed to and the magnitude of the resulting biological effect

A dose-response relationship describes how the severity of a biological effect increases (or changes) as the amount (dose) of a chemical substance to which an organism is exposed increases.

What are the four primary routes of exposure by which toxic substances can enter the human body?

Answer: Inhalation, ingestion, dermal absorption, and injection

Toxic substances can enter the human body through inhalation (breathing), ingestion (swallowing), dermal absorption (skin contact), and injection (puncture), with inhalation often being the most rapid route.

What is the difference between an 'acute' and 'chronic' toxic exposure?

Answer: Acute exposure occurs over a short period with high dose; chronic exposure occurs repeatedly over a long period at lower doses

Acute exposure refers to a single or short-term high-dose exposure, often causing immediate effects, while chronic exposure involves repeated or prolonged lower-dose exposures over months or years that may cause cumulative effects.

What does 'bioaccumulation' mean in the context of environmental toxicology?

Answer: The progressive increase in concentration of a substance in an organism because it is absorbed faster than it is eliminated

Bioaccumulation is the process by which a substance builds up in an organism's tissues over time because the rate of uptake exceeds the rate of metabolism and elimination.

What is the LD50 value used to measure in toxicology?

Answer: The lethal dose of a substance that kills 50% of a test population under specified conditions

LD50 (Lethal Dose 50) is a standard measure of acute toxicity representing the dose of a substance that is lethal to 50% of a test animal population under specified conditions; lower LD50 values indicate greater acute toxicity.