Detailed Explanation:

Answer: Option 2 — Only two

Two out of three statements regarding mercury pollution are correct. Gold mining activities and coal-based thermal power plants are both significant sources of mercury pollution globally. However, the claim that there is "no known safe level" is scientifically inaccurate, as regulatory bodies like WHO have established reference doses and tolerable intake levels for mercury exposure.

✅ Statement 1 – Correct: Gold mining, especially artisanal and small-scale mining, uses liquid mercury to amalgamate with gold particles, releasing significant mercury into water bodies and forests, notably in regions like the Amazon.

✅ Statement 2 – Correct: Coal-based thermal power plants (TPPs) are the largest anthropogenic source of mercury emissions, releasing mercury through fly ash and flue gases; studies show TPPs contribute over 80% of mercury emissions in countries like India.

❌ Statement 3 – Incorrect: While mercury is highly toxic, regulatory and scientific bodies establish safe exposure thresholds; WHO's Provisional Tolerable Weekly Intake for methylmercury is 1.6 µg/kg body weight/week, and drinking water limit is 1 µg/litre, demonstrating that safe levels do exist below which health risks are minimal.

📝 Short Notes: Mercury Pollution

• Sources of Mercury Pollution: Coal-fired power plants (largest source), artisanal gold mining, chlor-alkali industry, waste incinerators, cement production, and volcanic eruptions.
• Mercury in Environment: Converts to toxic methylmercury in aquatic systems through bacterial action; bioaccumulates in fish and biomagnifies up the food chain.
• Health Effects: Damages nervous system, kidneys, and developing fetuses; causes Minamata disease (severe neurological syndrome); particularly harmful to children and pregnant women.
• Minamata Convention: Global treaty (2013) to protect human health and environment from anthropogenic mercury emissions and releases; India ratified in 2018.
• Safe Exposure Levels: WHO guidelines: 1.6 µg/kg body weight/week for methylmercury; 1 µg/litre for drinking water; concept of "dose makes the poison" applies.
• Mercury from Coal Plants: Indian coal contains 0.05-0.5 ppm mercury; released during combustion; fly ash disposal in ponds creates aquatic ecosystems contaminated with mercury.