ABT Environmental Toxicology 2

Question 1

The EPA's Reference Dose (RfD) is defined as an estimate of daily exposure that:

Accepted Answer

Is likely to be without appreciable risk of deleterious effects over a lifetime

Answer

Causes a 1-in-a-million cancer risk over a lifetime

Answer

Represents the average human daily intake from all sources

Answer

Is the LOAEL divided by an uncertainty factor of 10

Question 2

Methylmercury exposure in humans primarily occurs through:

Accepted Answer

Consumption of contaminated fish and seafood

Answer

Inhalation of industrial emissions

Answer

Dermal contact with thermometers

Answer

Drinking water from industrial runoff

Question 3

Which class of pesticides inhibits acetylcholinesterase and was originally developed as nerve agents?

Accepted Answer

Organophosphates

Answer

Pyrethroids

Answer

Organochlorines

Answer

Neonicotinoids

Question 4

Lead exposure in children is most commonly associated with which source in older US homes?

Accepted Answer

Lead-based paint chips and dust

Answer

Drinking water from copper pipes

Answer

Gasoline combustion residues in soil

Answer

Food packaging leachates

Question 5

Dioxins (PCDDs) exert their toxic effects primarily through which molecular mechanism?

Accepted Answer

Activation of the aryl hydrocarbon receptor (AhR)

Answer

Direct DNA alkylation

Answer

Inhibition of cytochrome oxidase

Answer

Disruption of sodium channel gating

Question 6

The 'cancer slope factor' (CSF) is used in risk assessment to estimate risk for which type of toxic endpoint?

Accepted Answer

Linearized low-dose carcinogenicity risk

Answer

Threshold-based systemic toxicity

Answer

Neurotoxicity endpoints only

Answer

Reproductive toxicity endpoints