AEP Environmental Health & Toxicology 2 — Questions and Answers
Question 1: In human health risk assessment, cancer risk from chronic chemical exposure is calculated as:
- Risk = Exposure Concentration × Body Weight
- Risk = Chronic Daily Intake (CDI) × Cancer Slope Factor (CSF) (Correct answer)
- Risk = Hazard Quotient × Reference Dose
- Risk = NOAEL ÷ Uncertainty Factor
Correct answer: Risk = Chronic Daily Intake (CDI) × Cancer Slope Factor (CSF)
Cancer risk is determined by multiplying the Chronic Daily Intake by the Cancer Slope Factor (also called the oral slope factor or potency factor).
Question 2: The Hazard Quotient (HQ) used in non-cancer risk assessment is calculated as:
- Exposure dose divided by the reference dose (Correct answer)
- Reference dose divided by the exposure dose
- Cancer slope factor multiplied by chronic daily intake
- LD50 value divided by body weight
Correct answer: Exposure dose divided by the reference dose
HQ = Exposure Dose / Reference Dose; an HQ greater than 1.0 indicates potential concern for non-cancer adverse health effects.
Question 3: For residential sites with soil contamination, which exposure pathway typically contributes most to risk for young children?
- Dermal contact with surface water
- Inhalation of outdoor ambient air
- Incidental soil ingestion and dermal contact with soil (Correct answer)
- Consumption of contaminated fish tissue
Correct answer: Incidental soil ingestion and dermal contact with soil
Young children are especially vulnerable to soil ingestion (hand-to-mouth behavior) and dermal contact with contaminated surface soil at residential sites.
Question 4: ATSDR Toxicological Profiles serve which primary purpose in environmental health practice?
- Listing all CERCLA-regulated chemicals and their cleanup standards
- Providing comprehensive health effects and exposure data for specific hazardous substances (Correct answer)
- Establishing risk-based cleanup levels for Superfund sites
- Inventorying toxic chemical releases required by EPCRA Section 313
Correct answer: Providing comprehensive health effects and exposure data for specific hazardous substances
ATSDR Toxicological Profiles are peer-reviewed documents that comprehensively summarize health effects, exposure pathways, and toxicokinetic data for specific hazardous substances.
Question 5: Which statement most accurately describes the dose-response relationship in toxicology?
- Higher doses always produce proportionally equal increases in biological response
- The quantitative relationship between the amount of chemical exposure and the magnitude of biological effect in a population (Correct answer)
- A strictly linear relationship between carcinogen dose and tumor incidence
- The time elapsed between initial exposure and the appearance of clinical symptoms
Correct answer: The quantitative relationship between the amount of chemical exposure and the magnitude of biological effect in a population
The dose-response relationship is the fundamental toxicological principle describing how the severity or frequency of an effect varies with dose.
Question 6: Polychlorinated biphenyls (PCBs) are priority environmental contaminants primarily because they:
- Are highly water-soluble and migrate rapidly into drinking water aquifers
- Are persistent, lipophilic compounds that biomagnify through aquatic food chains (Correct answer)
- React photochemically with ozone to form acutely toxic byproducts
- Rapidly volatilize from soil surfaces and contaminate indoor air
Correct answer: Are persistent, lipophilic compounds that biomagnify through aquatic food chains
PCBs are highly chlorinated, chemically stable compounds that resist degradation, partition into lipid-rich tissues, and concentrate at upper trophic levels.
Question 7: Which term describes a chemical that causes malformations or developmental defects in a developing fetus?
- Mutagen
- Teratogen (Correct answer)
- Neurotoxin
- Sensitizer
Correct answer: Teratogen
A teratogen is an agent that disrupts normal fetal development, causing structural or functional birth defects when exposure occurs during gestation.
AEP Environmental Health & Toxicology 2
In human health risk assessment, cancer risk from chronic chemical exposure is calculated as: