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 one
(b) Only two ✓ UPSC's answer
(c) All three
(d) None

Why the answer is (b)

• Statement 1 is correct: artisanal and small-scale gold mining, which uses mercury to amalgamate gold, is the single largest source of mercury pollution globally under the Minamata Convention's assessments.

• Statement 2 is correct: coal contains trace mercury that is released when burnt, making coal-fired power plants the largest industrial emitters; India's plants are subject to mercury emission norms.

• Statement 3 is treated as not correct in the official key: WHO and regulators set reference doses and permissible limits for mercury (e.g. in fish, water and air), implying that a safe level of exposure is defined, unlike lead for which WHO states no safe level.

• Hence two statements, option (b).

Why the other options are wrong

(a) Only one: Both gold mining and coal plants are mercury sources, so the count is two.
(c) All three: Statement 3 is treated as incorrect: permissible exposure limits for mercury exist.
(d) None: Statements 1 and 2 are correct.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2023, held on 28 May 2023. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.