Authentic Classroom Explanation by IAS Monk

🧴 Q10. Bisphenol A (BPA) and Plastics

📌 Question
Bisphenol A (BPA), a cause of concern, is a structural/key component in the manufacture of which of the following kinds of plastics?

(a) Low-density polyethylene
(b) Polycarbonate
(c) Polyethylene terephthalate
(d) Polyvinyl chloride

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✅ Correct Answer: (b) Polycarbonate

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🧑‍🏫 Authentic Classroom Explanation by IAS Monk

From first principles to final option — the UPSC way.

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🔬 Concept First

Many plastics differ not by appearance, but by monomer chemistry.
BPA is not an additive — it is a building block.

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🔍 Option-wise Analysis

• Option (a): Low-density polyethylene (LDPE) ❌
  • Made from ethylene
  • No BPA involved
• Option (b): Polycarbonate ✅
  • BPA is a key monomer
  • Used to make hard, transparent plastics
• Option (c): Polyethylene terephthalate (PET) ❌
  • Made from ethylene glycol + terephthalic acid
  • BPA-free
• Option (d): Polyvinyl chloride (PVC) ❌
  • Made from vinyl chloride
  • Uses plasticisers like phthalates, not BPA

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🧬 Why BPA is a Concern

• Acts as an endocrine disruptor
• Mimics estrogen
• Can leach into food, especially when:
  • Heated
  • Containers are old or scratched

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🔍 Curiosity Raiser

Did you know?
“BPA-free” labels became common only after studies showed that heat dramatically increases BPA leaching into food and water.

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🧠 Enrichment Notes (UPSC Lens)

• Common products using polycarbonate:
  • Water bottles (older)
  • Food containers
  • Baby bottles (now restricted in many countries)
• Also found in:
  • Epoxy resins lining metal cans
• Common UPSC Trap:
  • Confusing PET bottles with BPA-containing plastics (❌ PET is BPA-free)
• Exam Value:
  • Links chemistry, public health, and regulation

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🪶 IAS Monk Closing Whisper

Sometimes the danger is not in what we eat, but in what holds our food.