Chemicals of Concern for UPSC: POPs, Mercury, PFAS, Basel, Rotterdam, Stockholm and Minamata, Montreal Protocol and Kigali
How UPSC Tests Chemicals of Concern
🎯 Exam priority: Tier-2. UPSC tests which chemical does what, which sector uses it and which treaty controls it. UPSC asked: mercury sources (artisanal gold mining and coal power plants, 2023); PFAS "forever chemicals" in water and packaging (2024); the uses of hydrofluorocarbons (2023); and a list of agricultural pesticides: carbofuran, methyl parathion, phorate and triazophos (2019).
Group the chemicals by the harm they do (persistence, toxicity, ozone depletion, warming) and then by the convention that controls them.
Persistent and Toxic Chemicals and the Conventions
Persistent and toxic chemicals
Chemical or group | Where it comes from | Why it matters |
Persistent organic pollutants (POPs) | Pesticides, industrial chemicals and unintended by-products | Stay in the environment, travel far and build up in food chains; controlled by the Stockholm Convention |
Mercury | Artisanal and small-scale gold mining and coal-fired power stations are major sources (2023 PYQ) | Highly toxic; controlled by the Minamata Convention |
PFAS ('forever chemicals') | Drinking water, food packaging and consumer goods | Persistent and bioaccumulative in animals (2024 PYQ: all three statements correct) |
Pesticides: carbofuran, methyl parathion, phorate, triazophos | Agricultural use; several are restricted or banned | The 2019 PYQ asked these as agricultural pesticides |
Hydrofluorocarbons (HFCs) | Aerosols, foam blowing and fire protection (not lubricants, 2023 PYQ) | Do not harm ozone but are powerful greenhouse gases |
The chemicals conventions and India
Convention | What it does | India |
Basel | Regulates transboundary movement of hazardous wastes and restricts trade in plastic waste | Ratified June 1992; prior informed consent for hazardous-waste trade under the 2016 Rules |
Stockholm | Eliminate intentionally produced POPs, reduce unintended ones, dispose of POPs waste safely | Banned 12 chemicals (the 'dirty dozen') on ratifying in January 2006; 7 more in October 2020; POPs Rules, 2018 |
Rotterdam | Prior Informed Consent (PIC) procedure for trade in listed hazardous chemicals (52 in Annex III) | Ratified May 2005; designated authorities are the fertilisers ministry (industrial chemicals) and agriculture ministry (pesticides) |
Minamata | Legally binding; covers the mercury life cycle including artisanal gold mining | Ratified June 2018; COP-6 (November 2025) extended phase-out dates for some mercury-added products to 2030 |
Global Framework on Chemicals | Succeeded SAICM in September 2023; life-cycle approach to chemicals and waste | India participates |
Ozone-Depleting Substances, Montreal Protocol and Kigali
Ozone-depleting substances and HFCs
The stratospheric ozone layer, 10 to 50 km above the Earth, shields us from harmful ultraviolet-B radiation. Ozone-depleting substances include CFCs, HCFCs, halons, carbon tetrachloride and methyl bromide; depletion raises the risk of skin cancer and cataracts, suppresses immunity and reduces crop yields.
The Vienna Convention (1985) set up the framework and the Montreal Protocol (1987) set the controls. The Protocol has universal ratification (198 UN member states) and has led to the phase-out of about 99 per cent of ozone-depleting substances globally.
India's HCFC phase-out: reductions of 10 per cent in 2015, 35 per cent in 2020 and 67.5 per cent in 2025, with complete phase-out in 2030 (apart from a small servicing tail till 2040). India completed the phase-out of the potent HCFC-141b in foam manufacturing. National rules: Ozone Depleting Substances (Regulation and Control) Rules, 2000 under the Environment (Protection) Act, 1986.
Kigali Amendment: phases down hydrofluorocarbons (HFCs), which do not harm ozone but warm the climate. India ratified on 27 September 2021 and will phase down in four steps: 10 per cent in 2032, 20 per cent in 2037, 30 per cent in 2042 and 85 per cent in 2047.
How UPSC Could Ask This Next
Matching: chemical to treaty (POPs to Stockholm, mercury to Minamata, PIC to Rotterdam, hazardous wastes to Basel, HFCs to Kigali).
Sources: where mercury, PFAS and POPs come from.
Dates: the HCFC schedule and the Kigali steps.
Uses: HFC and HCFC applications.
Further Reading
NCERT Biology (Class 12) and Geography textbooks, the India State of Forest Report, the MoEFCC Annual Report, the Economic Survey and the official lists cited in this note — the primary sources behind every figure above.
Test Yourself: Practice Questions and PYQs
Twelve practice questions on POPs, mercury, PFAS, the chemicals conventions and the ozone treaties, followed by the real UPSC Prelims questions.
Practice Questions
Q1. The Stockholm Convention deals with
(a) transboundary movement of hazardous wastes
(b) persistent organic pollutants
(c) wetlands
(d) mercury
Show answer
Answer: (b) — Basel covers hazardous wastes, Minamata mercury.
Q2. Which convention is a legally binding treaty on the life cycle of mercury, including artisanal and small-scale gold mining?
(a) Minamata Convention
(b) Basel Convention
(c) Rotterdam Convention
(d) Ramsar Convention
Show answer
Answer: (a) — India ratified the Minamata Convention in June 2018.
Q3. The Prior Informed Consent (PIC) procedure for international trade in listed hazardous chemicals is a feature of the
(a) Kyoto Protocol
(b) Cartagena Protocol
(c) Vienna Convention
(d) Rotterdam Convention
Show answer
Answer: (d) — 52 chemicals are listed in its Annex III.
Q4. How many chemicals did India ban on ratifying the Stockholm Convention in January 2006 (the 'dirty dozen')?
(a) 7
(b) 12
(c) 52
(d) 21
Show answer
Answer: (b) — Seven more were ratified in October 2020.
Q5. Which of the following are major sources of mercury pollution?
1. Artisanal and small-scale gold mining
2. Coal-fired power stations
3. Wind turbines
(a) 1 and 2 only
(b) 1, 2 and 3
(c) 1 and 3 only
(d) 2 and 3 only
Show answer
Answer: (a) — Wind power does not emit mercury.
Q6. PFAS, often called 'forever chemicals',
1. are found in drinking water, food packaging and consumer goods.
2. are persistent.
3. can bioaccumulate in animals.
(a) 1, 2 and 3
(b) 2 and 3 only
(c) 1 and 2 only
(d) 1 and 3 only
Show answer
Answer: (a) — All three statements are correct.
Q7. Hydrofluorocarbons (HFCs) are used in which of the following?
1. Aerosols
2. Foam blowing
3. Fire protection
4. Lubricants
(a) 2, 3 and 4 only
(b) 1 and 4 only
(c) 1, 2, 3 and 4
(d) 1, 2 and 3 only
Show answer
Answer: (d) — HFCs are not used as lubricants.
Q8. The Kigali Amendment to the Montreal Protocol aims to phase down
(a) methyl bromide
(b) hydrofluorocarbons
(c) chlorofluorocarbons
(d) carbon dioxide
Show answer
Answer: (b) — India ratified it on 27 September 2021.
Q9. Under India's Kigali schedule, the first reduction of 10 per cent in HFC production and consumption falls in
(a) 2025
(b) 2047
(c) 2040
(d) 2032
Show answer
Answer: (d) — Steps: 10 per cent in 2032, 20 per cent in 2037, 30 per cent in 2042 and 85 per cent in 2047.
Q10. The Montreal Protocol on Substances that Deplete the Ozone Layer was adopted in
(a) 1997
(b) 1992
(c) 1987
(d) 1985
Show answer
Answer: (c) — The Vienna Convention is 1985 and the Montreal Protocol 1987.
Q11. By 2025, India's accelerated HCFC phase-out schedule requires a reduction of
(a) 100 per cent
(b) 35 per cent
(c) 67.5 per cent
(d) 10 per cent
Show answer
Answer: (c) — Complete phase-out of production and consumption is due in 2030, with a servicing tail.
Q12. Which of the following are agricultural pesticides?
1. Carbofuran
2. Methyl parathion
3. Phorate
4. Triazophos
(a) 2 and 3 only
(b) 1, 2, 3 and 4
(c) 1 and 2 only
(d) 3 and 4 only
Show answer
Answer: (b) — All four are agricultural pesticides.
UPSC Previous Year Questions (PYQs)
Real UPSC Prelims questions, checked against the official paper and answer key.
Q1. (2023) Consider the following statements regarding mercury pollution :
1. Gold mining activity is a source of mercury pollution in the world.
2. Coal-based thermal power plants cause mercury pollution.
3. There is no known safe level of exposure to mercury.
How many of the above statements are correct?
(a) Only two
(b) All three
(c) None
(d) Only one
Show answer
Answer: (a) — Artisanal gold mining and coal-fired power stations are both major sources of mercury (1 and 2 are right). The key treats 3 as incorrect: mercury is highly toxic and exposure should be minimised, but WHO and other regulators have set reference levels for exposure. So two statements are correct.
Q2. (2024) With reference to perfluoroalkyl and polyfluoroalkyl substances (PFAS) thal are used in making many consumer product, consider the following statements :
1. PFAS are found to be widespread in drinking water, food and food packaging material.
2. PFAS are not easily degraded in the environment.
3. Persistent exposure to PFAS can lead to bioaccumulation in animal bodies.
Which of the statements given above are correct?
(a) 2 and 3 only
(b) 1, 2 and 3
(c) 1 and 3 only
(d) 1 and 2 only
Show answer
Answer: (b) — PFAS are persistent 'forever chemicals' found in drinking water, food packaging and consumer goods, and they bioaccumulate in animals, so all three statements are correct.
Q3. (2023) Consider the following:
1. Aerosols
2. Foam agents
3. Fire retardants
4. Lubricants In the making of how many of the above are hydrofluorocarbons used?
(a) Only three
(b) Only two
(c) All four
(d) Only one
Show answer
Answer: (a) — Hydrofluorocarbons are used in aerosols, foam blowing and fire protection, but not in lubricants, so three.
Q4. (2019) In India, the use of carbofuran, methyl parathion, phorate and triazophos is viewed with apprehension. These chemicals are used as
(a) preservatives in processed foods
(b) pesticides in agriculture
(c) fruit-ripening agents
(d) moisturizing agents in cosmetics
Show answer
Answer: (b) — Carbofuran, methyl parathion, phorate and triazophos are agricultural pesticides, several of them restricted or banned.
Mains Practice Questions
Use these to frame full-length answers. You don't have to answer one exactly — they show the angles UPSC tests, so let them guide which points you cover.
Why is the Montreal Protocol considered the most successful international environmental treaty? Does the Kigali Amendment extend that success to climate change?
Explain Persistent Organic Pollutants and the Stockholm Convention. How does India implement the Convention domestically?
Examine the case for tighter regulation of PFAS and mercury. What controls does India have?
Compare the Basel, Rotterdam, Stockholm and Minamata Conventions in terms of the chemicals or wastes covered and the instruments used.
Pesticide residue is a food-safety and environmental issue in India. Discuss regulation and alternatives.
UPSC Mains — Previous Years’ Questions on this topic (last 10 years)
No direct GS Mains question has been asked specifically on this topic in the last decade — it is primarily a Prelims area. Use the practice prompts above to stay exam-ready.