NEHA Hazardous Materials and Toxicology

Question 1

What is the fundamental principle of toxicology attributed to Paracelsus?

Accepted Answer

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

Answer

All substances are equally toxic

Answer

Natural substances are always safer than synthetic ones

Answer

Toxicity is determined solely by chemical structure

Question 2

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

Accepted Answer

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

Answer

The time required for a toxic substance to cause symptoms

Answer

The route by which a toxic substance enters the body

Answer

The rate at which the body eliminates a toxin

Question 3

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

Accepted Answer

Inhalation, ingestion, dermal absorption, and injection

Answer

Hearing, seeing, smelling, tasting

Answer

Air, water, soil, and food

Answer

Acute, chronic, subacute, and subchronic

Question 4

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

Accepted Answer

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

Answer

Acute exposure is always more dangerous than chronic exposure

Answer

Chronic exposure affects only specific organs while acute exposure is systemic

Answer

Acute and chronic refer to different toxicity mechanisms, not exposure duration

Question 5

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

Accepted Answer

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

Answer

The breakdown of toxic substances by microorganisms in the environment

Answer

The movement of toxic substances through soil and groundwater

Answer

The emission of toxic substances from industrial facilities

Question 6

What is the LD50 value used to measure in toxicology?

Accepted Answer

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

Answer

The concentration of a substance in drinking water causing illness in 50% of consumers

Answer

The time in days for 50% elimination of a substance from the body

Answer

The exposure level causing cancer in 50% of a population over a lifetime