Consider the following statements regarding mercury pollution:

Gold mining activity is a source of mercury pollution in the world.

Coal-based thermal power plants cause mercury pollution.

There is no known safe level of exposure to mercury.

How many of the above statements are correct? (UPSC Prelims 2023)

Question

The correct answer is [B] Only two.

Statement 1 – Correct: Artisanal and small-scale gold mining (ASGM) is the largest source of anthropogenic mercury emissions globally. In this process, mercury is mixed with gold-bearing silt to form an amalgam. When this amalgam is heated to recover the gold, the mercury vaporizes, leading to significant atmospheric pollution and soil contamination.
Statement 2 – Correct: Coal-based thermal power plants are a major industrial source of mercury. Mercury is a naturally occurring trace element in coal. During combustion, it is released as a gas in the flue discharge. While modern plants use scrubbers and electrostatic precipitators, a portion of the mercury still enters the environment.
Statement 3 – Incorrect: From a regulatory and clinical standpoint, there are defined thresholds for \"safe\" or \"tolerable\" exposure. Global health organizations, such as the World Health Organization (WHO) and environmental agencies like the US EPA, have established Reference Doses (RfD). These are specific concentrations (e.g., 5 ng/mL in blood or 20 ng/mL in urine) below which exposure is not expected to cause adverse health effects over a lifetime. The existence of these established limits contradicts the claim that \"no safe level\" is known.

GKToday Admin · Accepted Answer

Only two The correct answer is [B] Only two.

Statement 1 – Correct: Artisanal and small-scale gold mining (ASGM) is the largest source of anthropogenic mercury emissions globally. In this process, mercury is mixed with gold-bearing silt to form an amalgam. When this amalgam is heated to recover the gold, the mercury vaporizes, leading to significant atmospheric pollution and soil contamination.
Statement 2 – Correct: Coal-based thermal power plants are a major industrial source of mercury. Mercury is a naturally occurring trace element in coal. During combustion, it is released as a gas in the flue discharge. While modern plants use scrubbers and electrostatic precipitators, a portion of the mercury still enters the environment.
Statement 3 – Incorrect: From a regulatory and clinical standpoint, there are defined thresholds for \"safe\" or \"tolerable\" exposure. Global health organizations, such as the World Health Organization (WHO) and environmental agencies like the US EPA, have established Reference Doses (RfD). These are specific concentrations (e.g., 5 ng/mL in blood or 20 ng/mL in urine) below which exposure is not expected to cause adverse health effects over a lifetime. The existence of these established limits contradicts the claim that \"no safe level\" is known.

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