CIH Toxicology and Chemical Hazards 5 — Questions and Answers
Question 1: A worker exposed to beryllium dust develops granulomatous lung disease years after leaving the job. This pattern is consistent with:
- Acute chemical pneumonitis
- Chronic beryllium disease (berylliosis), an immune-mediated sensitization response (Correct answer)
- Occupational asthma from irritant exposure
- Chemical-induced pulmonary fibrosis from direct toxicity
Correct answer: Chronic beryllium disease (berylliosis), an immune-mediated sensitization response
Chronic beryllium disease is an immune-mediated granulomatous lung condition that can develop years after beryllium sensitization, even after exposure has ceased.
Question 2: Which route of exposure typically results in the fastest onset of systemic toxic effects?
- Dermal absorption
- Oral ingestion
- Intravenous injection (Correct answer)
- Inhalation
Correct answer: Intravenous injection
Intravenous injection delivers a substance directly into the bloodstream, producing the fastest onset of systemic effects with 100% bioavailability.
Question 3: The concept of a 'threshold' in toxicology implies that:
- Every dose of a chemical produces some measurable biological response
- Below a certain dose, no adverse effect is expected to occur (Correct answer)
- All toxic effects occur at the same dose level
- Carcinogens always produce effects proportional to dose
Correct answer: Below a certain dose, no adverse effect is expected to occur
The threshold concept holds that there is a dose below which no adverse effect occurs because biological defense mechanisms can handle the insult.
Question 4: Hexane exposure in industrial settings is primarily associated with which occupational disease?
- Silicosis
- Peripheral neuropathy (n-hexane neuropathy) (Correct answer)
- Occupational asthma
- Hepatocellular carcinoma
Correct answer: Peripheral neuropathy (n-hexane neuropathy)
n-Hexane is metabolized to 2,5-hexanedione, which causes peripheral neuropathy by cross-linking neurofilament proteins in axons.
Question 5: When assessing mixture toxicity for chemicals acting by the same mechanism, industrial hygienists apply the concept of:
- Synergistic interaction requiring special adjustment factors
- Dose addition (additive toxicity) to evaluate combined exposure (Correct answer)
- Independent action where only the most toxic component matters
- Potentiation where one component amplifies the other's effects
Correct answer: Dose addition (additive toxicity) to evaluate combined exposure
For chemicals with similar mechanisms of action, dose addition is applied, meaning their combined effect equals the sum of their proportional contributions to the TLV.
Question 6: Which biomarker type directly measures the amount of a chemical or its metabolite in a biological specimen, reflecting internal dose?
- Biomarker of susceptibility
- Biomarker of exposure (Correct answer)
- Biomarker of effect
- Biomarker of response
Correct answer: Biomarker of exposure
Biomarkers of exposure measure the chemical or its metabolite in blood, urine, or exhaled air, directly reflecting internal dose received.
Question 7: The primary target organ for silica dust exposure leading to occupational disease is the:
- Liver
- Kidney
- Lung (Correct answer)
- Peripheral nervous system
Correct answer: Lung
Crystalline silica dust causes silicosis, a fibrotic lung disease resulting from macrophage-mediated inflammatory response to inhaled silica particles.
CIH Toxicology and Chemical Hazards 5
A worker exposed to beryllium dust develops granulomatous lung disease years after leaving the job.
This pattern is consistent with: