Mixed Deck — All ABT Topics Flashcards

Endocrine-disrupting chemicals (EDCs) can mimic or block hormones. Which effect describes a chemical that binds estrogen receptors without activating them?

Answer: Estrogen receptor antagonism

An estrogen receptor antagonist binds to estrogen receptors but does not activate transcription, effectively blocking endogenous estrogen from exerting its effects.

Which mathematical model best describes the kinetics of ethanol elimination from the blood at typical intoxicating concentrations?

Answer: Zero-order kinetics (Michaelis-Menten saturation)

At intoxicating ethanol concentrations, liver alcohol dehydrogenase (ADH) is saturated, and ethanol is eliminated at a constant rate (~0.015–0.020 g/dL/hr) independent of concentration — zero-order kinetics.

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

Answer: Lead-based paint chips and dust

Lead-based paint used in homes built before 1978 is the most common source of lead exposure in US children through ingestion of paint chips and inhalation of dust.

The area under the concentration-time curve (AUC) is directly proportional to which pharmacokinetic parameter?

Answer: Bioavailability / clearance (F/CL)

AUC = F × Dose / CL; for a given dose and bioavailability, AUC is inversely proportional to clearance and directly represents total systemic exposure.

Methylmercury exposure in humans primarily occurs through:

Answer: Consumption of contaminated fish and seafood

Methylmercury bioaccumulates in fish and seafood, making dietary consumption of large predatory fish (tuna, swordfish) the primary human exposure route.

The presence of which compound in improperly stored potatoes can cause gastrointestinal and neurological disorders?

Answer: Solanine

Solanine is a glycoalkaloid toxin naturally present in potatoes, especially in green parts, sprouts, and eyes, or in potatoes that have been improperly stored and exposed to light. Ingesting high levels of solanine can cause a range of symptoms, from gastrointestinal upset like nausea and vomiting to neurological disorders such as headaches and hallucinations. It's crucial to avoid consuming green or sprouting potatoes.

Which drug is associated with 'excited delirium syndrome' and sudden death in forensic cases, often involving restraint?

Answer: Cocaine or methamphetamine

Excited delirium syndrome is frequently associated with stimulant drugs (cocaine, methamphetamine) and is characterized by hyperthermia, agitation, superhuman strength, and sudden death.

Which period of prenatal development is most sensitive to teratogenic agents causing structural malformations?

Answer: Weeks 3–8 (organogenesis)

The embryonic period (weeks 3–8), when organogenesis occurs, is the most sensitive window for structural teratogenesis because organ rudiments are being established.

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

Answer: Linearized low-dose carcinogenicity risk

The cancer slope factor (CSF) is used in the linearized multistage model to estimate the incremental lifetime cancer risk per unit of daily exposure for carcinogens.

Which mechanism explains the selective vulnerability of the fetal brain to methylmercury neurotoxicity?

Answer: Incomplete blood-brain barrier and active neuronal migration in the developing CNS

The immature blood-brain barrier and ongoing neuronal migration, proliferation, and differentiation during fetal development make the fetal CNS highly vulnerable to methylmercury neurotoxicity.

The ACGIH Biological Exposure Index (BEI) represents:

Answer: The biomarker level observed in healthy workers exposed at the TLV

BEIs are reference values corresponding to biomarker levels found in healthy workers exposed at the TLV, used as guidelines for occupational biological monitoring programs.

What is the purpose of the GRAS (Generally Recognized As Safe) designation by the FDA?

Answer: To certify food additives that are safe for consumption

The GRAS (Generally Recognized As Safe) designation by the FDA is used to certify food additives that are considered safe for consumption under their intended conditions of use. This designation is based on extensive scientific evidence or historical use, allowing certain substances to be added to food without formal premarket approval. It helps ensure the safety of the food supply.

Under OSHA's Hazard Communication Standard (HazCom 2012), Safety Data Sheets (SDS) must follow which standardized format?

Answer: GHS 16-section format

OSHA's HazCom 2012 aligned with the Globally Harmonized System (GHS) of Classification and Labelling of Chemicals, mandating a standardized 16-section SDS.

Digoxin toxicity is potentiated by which electrolyte abnormality?

Answer: Hypokalemia

Hypokalemia increases digoxin toxicity because potassium and digoxin compete for the same binding site on the Na+/K+-ATPase pump.

CYP1A1 induction by polycyclic aromatic hydrocarbons (PAHs) increases risk of carcinogenicity because:

Answer: CYP1A1 converts PAH procarcinogens to reactive diol-epoxides that form DNA adducts

CYP1A1 (induced by PAH-AhR signaling) converts PAH procarcinogens like benzo[a]pyrene to reactive diol-epoxide metabolites (BPDE) that form covalent DNA adducts leading to mutagenesis.

The Michaelis-Menten equation describes enzyme-mediated metabolism; at concentrations far below Km, metabolism approaches:

Answer: First-order kinetics (rate proportional to concentration)

When substrate concentration is far below Km (the Michaelis constant), the enzyme is far from saturated and the reaction velocity is approximately proportional to substrate concentration — i.e., pseudo-first-order kinetics.

The hepatic extraction ratio (ER) of a drug determines whether its clearance is sensitive to changes in:

Answer: Hepatic blood flow for high-ER drugs and protein binding for low-ER drugs

High extraction ratio (ER > 0.7) drugs have flow-limited clearance sensitive to hepatic blood flow, while low ER drugs (< 0.3) have capacity-limited clearance sensitive to enzyme activity and protein binding.

Which type of asbestos fiber is associated with the greatest risk of mesothelioma due to its biopersistent, thin, needle-like morphology?

Answer: Crocidolite (blue asbestos)

Crocidolite (blue asbestos), an amphibole fiber, carries the highest mesothelioma risk due to its biopersistance and fiber dimensions that allow deep lung penetration.

In the hierarchy of occupational health controls, which control method is most preferred because it completely removes the hazard?

Answer: Elimination

Elimination is the highest priority in the hierarchy of controls because it completely removes the hazard from the workplace, providing the greatest level of worker protection.

Minamata disease is caused by occupational and environmental exposure to which toxic substance?

Answer: Methylmercury

Minamata disease results from methylmercury poisoning documented in Minamata Bay, Japan, where industrial effluent contaminated the marine food chain.