CIH - Certified Industrial Hygienist Toxicology and Chemical Hazards Questions and Answers

Question 1

A worker is exposed to two chemicals simultaneously. Chemical A has a toxic effect of 2 units, and Chemical B has a toxic effect of 3 units. When combined, the total toxic effect is measured as 10 units. Which type of chemical interaction does this scenario describe?

Accepted Answer

Synergistic

Answer

A synergistic effect occurs when the combined effect of two or more chemicals is greater than the sum of their individual effects. In this case, the sum of the individual effects is 2 + 3 = 5, but the combined effect is 10, which is significantly greater.

Question 2

Which of the following is the primary target organ for toxic effects from both acute and chronic inhalation exposure to toluene?

Accepted Answer

Central Nervous System (CNS)

Answer

The central nervous system (CNS) is the primary target organ for toluene toxicity from both short-term (acute) and long-term (chronic) exposures. Symptoms of CNS effects include fatigue, confusion, headaches, dizziness, and impaired coordination.

Question 3

An industrial hygienist is evaluating a substance's acute toxicity. The data sheet reports an 'LC50 of 100 ppm (rat, 4 hr)'. What does this value represent?

Accepted Answer

The airborne concentration that is lethal to 50% of the rat population following a 4-hour exposure.

Answer

LC50 stands for Lethal Concentration 50%. It refers to the concentration of a substance in the air that is expected to cause the death of 50% of a defined experimental animal population during a specified exposure period (in this case, 4 hours).

Question 4

Organophosphate pesticides primarily exert their toxic effect through which mechanism of action?

Accepted Answer

Inhibiting the enzyme acetylcholinesterase

Answer

The primary mechanism of toxicity for organophosphates is the inhibition of acetylcholinesterase (AChE). This enzyme is responsible for breaking down the neurotransmitter acetylcholine. Inhibition of AChE leads to an accumulation of acetylcholine, causing overstimulation of the nervous system.

Question 5

A worker in a poorly ventilated garage is exposed to carbon monoxide (CO) from a running engine. According to the ACGIH, what is the Threshold Limit Value - Time-Weighted Average (TLV-TWA) for CO?

Accepted Answer

25 ppm

Answer

The American Conference of Governmental Industrial Hygienists (ACGIH) has established a Threshold Limit Value - Time-Weighted Average (TLV-TWA) for carbon monoxide of 25 ppm for a normal 8-hour workday and 40-hour workweek.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Toxicology and Chemical Hazards Questions and Answers