An epidemiologist investigating lung cancer cases among non-smoking women finds a strong association with a colourless, odourless radioactive gas that seeps from soil and accumulates in poorly ventilated ground-floor homes. The gas and its principal source are:
- A Radon, derived from uranium decay in soil and rock beneath dwellings ✓
- B Carbon monoxide, derived from indoor chulha combustion
- C Formaldehyde, derived from pressed wood furniture
- D Krypton-85, derived from nuclear fallout deposition
Correct answer: A. Radon, derived from uranium decay in soil and rock beneath dwellings
Explanation
Radon, a decay product of uranium-238 present in soil and building materials, is recognised as the second leading cause of lung cancer overall and the leading cause among non-smokers. Its alpha emissions damage bronchial epithelium. Carbon monoxide causes acute toxicity, not cancer, and formaldehyde is linked mainly to nasopharynge carcinoma, which eliminates the closest distractors.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.