1. : Environmental toxicology mainly studies the effects of?
(A) Radiation on planets
(B) Toxic substances on living organisms and ecosystems
(C) Space pollution
(D) Soil erosion only
2. : The dose at which a toxic substance kills 50% of a test population is called?
(A) TD50
(B) LD50
(C) ED50
(D) RD50
3. : Bioaccumulation refers to?
(A) The breakdown of toxins in soil
(B) The gradual buildup of toxins in living organisms
(C) The dilution of toxins in rivers
(D) The transfer of toxins to the atmosphere
4. : Which heavy metal is most commonly linked to neurological damage in children?
(A) Zinc
(B) Lead
(C) Iron
(D) Calcium
5. : Which of the following toxins is produced by certain blue-green algae?
(A) Dioxin
(B) Microcystin
(C) Arsenic
(D) Mercury
6. : The branch of toxicology that deals with the effects of chemicals on ecosystems is called?
(A) Medical toxicology
(B) Environmental toxicology
(C) Forensic toxicology
(D) Clinical toxicology
7. : Which organ is primarily responsible for detoxification of chemicals in the human body?
(A) Heart
(B) Kidneys
(C) Liver
(D) Lungs
8. : Persistent Organic Pollutants (POPs) are dangerous because they are?
(A) Easily degradable
(B) Non-biodegradable and bioaccumulative
(C) Harmless to ecosystems
(D) Used as natural fertilizers
9. : Which toxic metal is commonly associated with “Minamata disease”?
(A) Mercury
(B) Arsenic
(C) Cadmium
(D) Chromium
10. : The most toxic form of mercury to humans is?
(A) Elemental mercury
(B) Methylmercury
(C) Inorganic mercury salts
(D) Ionic mercury
11. : What does the term “carcinogen” refer to?
(A) A chemical that causes birth defects
(B) A chemical that causes cancer
(C) A chemical that causes organ failure
(D) A chemical that causes allergies
12. : Which gas is most dangerous in poorly ventilated indoor environments?
(A) Nitrogen
(B) Carbon monoxide
(C) Oxygen
(D) Hydrogen
13. : Biomagnification means?
(A) Dilution of toxins in soil
(B) Increase in toxin concentration along the food chain
(C) Degradation of toxins in air
(D) Removal of toxins by plants
14. : DDT is an example of a?
(A) Herbicide
(B) Insecticide
(C) Fungicide
(D) Rodenticide
15. : Which organ is most affected by nephrotoxic substances?
(A) Lungs
(B) Kidneys
(C) Heart
(D) Stomach
16. : The toxic effects of asbestos exposure are mainly on?
(A) Brain
(B) Skin
(C) Lungs
(D) Kidneys
17. : “Itai-Itai disease” in Japan was caused by which toxic metal?
(A) Arsenic
(B) Cadmium
(C) Lead
(D) Mercury
18. : The term “teratogen” refers to substances that cause?
(A) Genetic mutations
(B) Birth defects during development
(C) Heart diseases
(D) Allergic reactions
19. : Which toxic metal is commonly found in groundwater in South Asia?
(A) Arsenic
(B) Zinc
(C) Nickel
(D) Cobalt
20. : The most widely known greenhouse gas with toxic effects at high concentrations is?
(A) Oxygen
(B) Carbon dioxide
(C) Nitrogen
(D) Helium
21. : Polychlorinated biphenyls (PCBs) are mainly used in?
(A) Plastic toys
(B) Electrical equipment and coolants
(C) Fertilizers
(D) Pesticides
22. : Which organ is primarily affected by hepatotoxic substances?
(A) Lungs
(B) Liver
(C) Kidneys
(D) Brain
23. : Cyanide poisoning primarily affects which system?
(A) Digestive system
(B) Respiratory system
(C) Circulatory system
(D) Immune system
24. : The pesticide Bhopal disaster in India involved which toxic chemical?
(A) Methyl isocyanate
(B) DDT
(C) Benzene
(D) Mercury chloride
25. : The concept of “threshold dose” in toxicology refers to?
(A) The maximum tolerable dose
(B) The minimum dose below which no effect is observed
(C) The dose that kills all organisms
(D) The average dose consumed daily
26. : Radon gas exposure is most strongly associated with?
(A) Stomach cancer
(B) Lung cancer
(C) Skin cancer
(D) Liver cancer
27. : Which of the following is a neurotoxin?
(A) Mercury
(B) Asbestos
(C) Lead
(D) Both Mercury and Lead
28. : Phytoremediation is the process of using?
(A) Bacteria to degrade pollutants
(B) Plants to absorb or detoxify pollutants
(C) Chemicals to neutralize toxins
(D) Machines to filter toxins
29. : The Stockholm Convention is related to control of?
(A) Water pollution
(B) Persistent Organic Pollutants (POPs)
(C) Carbon dioxide emissions
(D) Radioactive waste
30. : Which chemical is known as the “silent killer” due to its odorless and colorless properties?
(A) Methane
(B) Carbon monoxide
(C) Ozone
(D) Hydrogen
31. : Endocrine disruptors interfere with which system?
(A) Nervous system
(B) Hormonal system
(C) Respiratory system
(D) Immune system
32. : The main toxic effect of benzene exposure is?
(A) Liver cancer
(B) Lung cancer
(C) Blood disorders like leukemia
(D) Kidney failure
33. : Which toxic chemical is used in antifreeze and is sweet-tasting but deadly?
(A) Ethylene glycol
(B) Benzene
(C) Acetone
(D) Methanol
34. : The biological half-life of a toxic substance refers to?
(A) Time required to double in concentration
(B) Time required for half of it to be eliminated from the body
(C) Time required for complete metabolism
(D) Time taken to accumulate in tissues
35. : Which radioactive element was released in the Chernobyl disaster?
(A) Uranium-235
(B) Cesium-137
(C) Plutonium-239
(D) Radium-226
36. : Mercury poisoning from industrial discharge was observed in which Japanese bay?
(A) Osaka Bay
(B) Minamata Bay
(C) Tokyo Bay
(D) Nagasaki Bay
37. : What type of toxin is aflatoxin, produced by fungi?
(A) Carcinogen
(B) Neurotoxin
(C) Endocrine disruptor
(D) Allergen
38. : Which toxic gas has a characteristic rotten-egg smell?
(A) Ozone
(B) Hydrogen sulfide
(C) Ammonia
(D) Methane
39. : The toxicity of a chemical depends on?
(A) Dose
(B) Duration of exposure
(C) Route of entry
(D) All of the above
40. : The unit commonly used to measure toxic gas concentration in air is?
(A) Milligrams per liter (mg/L)
(B) Parts per million (ppm)
(C) Grams per kilogram (g/kg)
(D) Newtons per cubic meter (N/m³)
41. : Which of the following is considered an emerging environmental contaminant?
(A) Microplastics
(B) Oxygen
(C) Helium
(D) Nitrogen
42. : The toxic effects of alcohol are mainly due to?
(A) Methanol content
(B) Ethanol metabolism to acetaldehyde
(C) Presence of carbon dioxide
(D) Sulfur impurities
43. : Which insecticide is known to disrupt the nervous system by inhibiting acetylcholinesterase?
(A) DDT
(B) Organophosphates
(C) Glyphosate
(D) Atrazine
44. : Which metal contaminant is commonly found in batteries and poses health risks?
(A) Lead
(B) Nickel
(C) Cadmium
(D) All of the above
45. : Which toxic gas caused mass fatalities in Bhopal, India, in 1984?
(A) Hydrogen sulfide
(B) Carbon monoxide
(C) Methyl isocyanate
(D) Sulfur dioxide
46. : The process of testing chemicals on animals to evaluate toxicity is called?
(A) Epidemiology
(B) Bioassay
(C) Pathology
(D) Immunology
47. : Which of the following is a known nephrotoxin?
(A) Cadmium
(B) Benzene
(C) Methane
(D) Ammonia
48. : The safe level of arsenic in drinking water recommended by WHO is?
(A) 100 ppb
(B) 50 ppb
(C) 10 ppb
(D) 1 ppb
49. : Lead poisoning is also known as?
(A) Plumbism
(B) Minamata disease
(C) Itai-Itai disease
(D) Asbestosis
50. : Which branch of science studies the adverse effects of chemical substances on living organisms?
(A) Ecology
(B) Toxicology
(C) Pharmacology
(D) Geology