MCQ on Occupational and Environmental Toxicology

🟢 Easy (1–20)

Which of the following is a common environmental toxin?
a) Lead ✅
b) Paracetamol
c) Naloxone
d) Ibuprofen
Explanation: Lead is a common environmental contaminant, especially in polluted areas.
Which occupation is most at risk for exposure to asbestos?
a) Teachers
b) Miners ✅
c) Software engineers
d) Chefs
Explanation: Miners working in asbestos-containing environments are at risk.
Which chemical is commonly found in cigarette smoke and is harmful to health?
a) Cyanide
b) Benzene ✅
c) Nitrogen
d) Oxygen
Explanation: Benzene is a carcinogen found in cigarette smoke.
What is the primary effect of carbon monoxide poisoning?
a) Liver failure
b) Respiratory depression
c) Hypoxia ✅
d) Hyperkalemia
Explanation: CO binds to hemoglobin, reducing oxygen delivery to tissues.
Which metal is commonly associated with “Mad Hatter’s disease”?
a) Lead
b) Mercury ✅
c) Zinc
d) Copper
Explanation: Mercury exposure, particularly in hat-making, causes neurological symptoms.
Which of the following is a recognized occupational carcinogen?
a) Asbestos ✅
b) Vitamin D
c) Carbohydrates
d) Zinc
Explanation: Asbestos exposure is known to cause lung cancer and mesothelioma.
Which organ is primarily affected by toxic exposure to solvents?
a) Heart
b) Liver
c) Kidneys
d) Brain ✅
Explanation: Solvent exposure can damage the central nervous system, leading to cognitive issues.
Which type of radiation exposure can cause occupational cancers?
a) Alpha radiation
b) Beta radiation
c) Gamma radiation ✅
d) Microwave radiation
Explanation: Gamma radiation exposure increases the risk of various cancers.
Which disease is caused by long-term exposure to silica dust?
a) Mesothelioma
b) Silicosis ✅
c) Parkinson’s disease
d) COPD
Explanation: Silicosis is a lung disease caused by inhaling crystalline silica dust.
Which is a common environmental pollutant affecting water quality?
a) Cyanide
b) Pesticides ✅
c) Sodium chloride
d) Nitrogen
Explanation: Pesticides can contaminate water sources and harm aquatic ecosystems.
Occupational exposure to which substance is linked to an increased risk of leukemia?
a) Arsenic
b) Benzene ✅
c) Methanol
d) Ammonia
Explanation: Benzene is a known carcinogen that increases leukemia risk.
Which of the following is an example of an endocrine-disrupting chemical?
a) Bisphenol A (BPA) ✅
b) Calcium carbonate
c) Acetaminophen
d) Glucose
Explanation: BPA is a chemical that disrupts hormonal systems, often found in plastics.
Which of the following occupations involves exposure to pesticides?
a) Graphic designers
b) Farmers ✅
c) Teachers
d) Bankers
Explanation: Farmers and agricultural workers are at risk for pesticide exposure.
Which of the following is a common environmental toxin found in air pollution?
a) Carbon dioxide
b) Nitrogen dioxide ✅
c) Oxygen
d) Helium
Explanation: Nitrogen dioxide is a harmful pollutant commonly found in urban air.
What is the most likely outcome of chronic lead exposure in children?
a) Liver damage
b) Neurological impairment ✅
c) Kidney failure
d) Respiratory issues
Explanation: Lead poisoning can cause developmental delays and cognitive deficits in children.
Which of the following is NOT a heavy metal?
a) Lead
b) Cadmium
c) Mercury
d) Sodium ✅
Explanation: Sodium is not a heavy metal and is essential in small amounts.
What is a major source of indoor air pollution in homes?
a) Wood burning stoves ✅
b) Wind turbines
c) Solar panels
d) Electric heaters
Explanation: Wood-burning stoves emit particulate matter that can degrade indoor air quality.
Which of the following diseases is linked to occupational exposure to coal dust?
a) Pneumoconiosis ✅
b) Asthma
c) Tuberculosis
d) Hepatitis
Explanation: Pneumoconiosis is a lung disease caused by long-term exposure to coal dust.
Which of the following is a common environmental toxin in agricultural settings?
a) Formaldehyde
b) Pesticides ✅
c) Lead
d) Carbon dioxide
Explanation: Pesticides used in farming can contaminate the environment and harm health.
What is the main target of carbon tetrachloride toxicity?
a) Kidneys
b) Lungs
c) Liver ✅
d) Heart
Explanation: Carbon tetrachloride is hepatotoxic, damaging the liver.

🟡 Moderate (21–40)

Which of the following is an example of an occupational exposure to a neurotoxin?
a) Asbestos
b) Lead ✅
c) Silica
d) Radon
Explanation: Lead exposure can cause neurological damage, especially in children.
Which environmental contaminant is most likely to cause respiratory issues in urban areas?
a) Nitrogen dioxide ✅
b) Benzene
c) Methane
d) Carbon monoxide
Explanation: Nitrogen dioxide from vehicle emissions causes respiratory issues.
Which toxin can be found in fish and is associated with mercury exposure?
a) DDT
b) Methylmercury ✅
c) PCB
d) Vinyl chloride
Explanation: Methylmercury accumulates in fish and is toxic to the nervous system.
Which of the following is a known effect of long-term exposure to high levels of radon?
a) Lung cancer ✅
b) Bladder cancer
c) Liver cirrhosis
d) Cardiovascular disease
Explanation: Radon exposure increases the risk of lung cancer.
Which chemical is commonly associated with occupational exposure in the printing industry?
a) Carbon monoxide
b) Benzene ✅
c) Methanol
d) Acetone
Explanation: Benzene is often used in the printing industry and is a carcinogen.
Which organ is primarily affected by vinyl chloride exposure?
a) Lungs
b) Liver ✅
c) Kidneys
d) Heart
Explanation: Vinyl chloride is hepatotoxic and a known carcinogen.
Which of the following chemicals is linked to environmental pollution caused by industrial processes?
a) Polycyclic aromatic hydrocarbons (PAHs) ✅
b) Nitrate
c) Hydrogen sulfide
d) Oxygen
Explanation: PAHs are released during combustion processes and can cause cancer.
Chronic exposure to which substance is most likely to cause kidney damage in workers?
a) Acetone
b) Cadmium ✅
c) Nitroglycerin
d) Ammonia
Explanation: Cadmium exposure is a major cause of kidney toxicity in industrial workers.
Which disease is most commonly associated with arsenic exposure?
a) Skin cancer ✅
b) Lung cancer
c) Liver cirrhosis
d) Pancreatic cancer
Explanation: Chronic arsenic exposure increases the risk of skin cancer.
Which occupational exposure is linked to the development of “Black Lung Disease”?
a) Coal dust ✅
b) Asbestos
c) Lead
d) Silica
Explanation: Long-term exposure to coal dust causes pneumoconiosis (Black Lung Disease).
Which of the following is used to measure the exposure of workers to toxic substances?
a) Urinary biomarkers ✅
b) MRI scans
c) Chest X-rays
d) Electrocardiograms
Explanation: Biomarkers in urine can indicate exposure to toxic chemicals.
Which of the following is a common method for controlling hazardous air pollutants in workplaces?
a) Increased ventilation ✅
b) Use of oral medication
c) Surgical masks
d) Avoiding the workplace
Explanation: Adequate ventilation helps reduce airborne contaminants in the workplace.
Which environmental factor increases the risk of skin cancer?
a) High levels of carbon monoxide
b) Ultraviolet radiation ✅
c) Radon
d) Asbestos
Explanation: UV radiation is the leading cause of skin cancer.
The toxicological effects of which substance are monitored through blood lead levels?
a) Cadmium
b) Lead ✅
c) Mercury
d) Arsenic
Explanation: Blood lead levels are measured to assess poisoning and exposure.
Which of the following is a major concern for workers exposed to solvent vapors?
a) Neurological disorders ✅
b) Hearing loss
c) Bone disease
d) Heart disease
Explanation: Solvent vapors are neurotoxic and can cause cognitive decline.
Which of the following is used to prevent occupational mercury exposure?
a) Using personal protective equipment (PPE) ✅
b) Avoiding all medical treatments
c) Drinking plenty of water
d) Reducing salt intake
Explanation: PPE helps protect workers from mercury exposure in industrial settings.
Which environmental toxin is primarily linked to water contamination from industrial waste?
a) PCB ✅
b) Sulfur dioxide
c) Nitrogen oxides
d) Carbon dioxide
Explanation: Polychlorinated biphenyls (PCBs) are persistent pollutants in water.
Which occupation is most likely to be exposed to silica dust?
a) Nurses
b) Construction workers ✅
c) Office workers
d) Teachers
Explanation: Construction workers often work with materials that release silica dust.
Which of the following environmental pollutants is a major cause of smog in urban areas?
a) Methane
b) Nitrogen oxides ✅
c) Carbon dioxide
d) Radon
Explanation: Nitrogen oxides react in the atmosphere to form smog.
Which metal exposure is commonly associated with occupational kidney damage?
a) Iron
b) Cadmium ✅
c) Zinc
d) Copper
Explanation: Cadmium exposure causes kidney toxicity, especially in industrial workers.

🔴 Hard (41–50)

Which of the following occupational exposures is strongly associated with hepatic angiosarcoma?
a) Benzene
b) Vinyl chloride ✅
c) Lead
d) Toluene
Explanation: Vinyl chloride, used in plastic manufacturing, is linked to hepatic angiosarcoma, a rare liver cancer.
Bioaccumulation of which environmental toxin is a concern in Arctic marine ecosystems?
a) Carbon monoxide
b) Polychlorinated biphenyls (PCBs) ✅
c) Nitrogen oxides
d) Methane
Explanation: PCBs persist in cold environments and accumulate in the food chain, affecting top predators and indigenous populations.
Which occupational toxin inhibits cytochrome oxidase and leads to cellular hypoxia?
a) Methanol
b) Cyanide ✅
c) Lead
d) Dioxin
Explanation: Cyanide disrupts mitochondrial electron transport, inhibiting oxygen use and causing rapid cellular hypoxia.
Which environmental pollutant acts as an endocrine disruptor and has been banned in many countries?
a) Arsenic
b) DDT ✅
c) Nitrate
d) Carbon tetrachloride
Explanation: DDT, once widely used as a pesticide, disrupts hormonal systems and persists in the environment.
Which biomarker is used to assess chronic cadmium exposure in industrial workers?
a) Urinary creatinine
b) Urinary β2-microglobulin ✅
c) Blood urea nitrogen
d) Serum calcium
Explanation: β2-microglobulin levels in urine increase with cadmium-induced kidney tubular damage.
Which of the following is classified as a Group 1 carcinogen by the IARC due to occupational exposure?
a) Carbon dioxide
b) Wood dust ✅
c) Propylene glycol
d) Ascorbic acid
Explanation: Wood dust is a confirmed human carcinogen (Group 1), especially in furniture and wood product manufacturing.
Which of the following environmental toxins is known to interfere with thyroid hormone synthesis?
a) Benzene
b) Perchlorate ✅
c) Methanol
d) Ethylene glycol
Explanation: Perchlorate competes with iodine uptake in the thyroid, disrupting hormone production.
Which analytical technique is most suitable for detecting trace levels of environmental heavy metals in biological samples?
a) Enzyme immunoassay
b) Gas chromatography
c) Atomic absorption spectroscopy (AAS) ✅
d) UV spectroscopy
Explanation: AAS is the standard method for detecting and quantifying trace metals in samples.
Which occupational group is most at risk for noise-induced hearing loss (NIHL)?
a) Librarians
b) Miners ✅
c) Pharmacists
d) Dentists
Explanation: Miners operate heavy machinery in confined spaces, exposing them to prolonged loud noise.
What is the primary toxic effect of organophosphate pesticide exposure?
a) DNA damage
b) Cholinesterase inhibition ✅
c) Oxidative phosphorylation
d) Sodium channel blockade
Explanation: Organophosphates inhibit acetylcholinesterase, leading to accumulation of acetylcholine and cholinergic crisis.

🟢 Easy (1–20)

🟡 Moderate (21–40)

🔴 Hard (41–50)

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