Correct Option
The correct option is Only two
Explanation
Mercury is a highly toxic heavy metal pollutant with multiple anthropogenic sources. Its environmental and health impacts are governed by the nature of exposure, concentration, and the form in which mercury occurs.
Statement-wise Analysis
- Statement 1 - Correct: Artisanal and small-scale gold mining is one of the largest sources of anthropogenic mercury pollution globally. Mercury is used to amalgamate gold particles from ore sediments, and the subsequent burning of this amalgam releases mercury vapour into the surrounding environment. This process causes significant contamination of soil, water bodies, and air, particularly in regions of Africa, South America, and Southeast Asia where such mining is prevalent.
- Statement 2 - Correct: Coal contains trace amounts of mercury as a naturally occurring impurity. When coal is combusted in thermal power plants, mercury is released into the atmosphere along with other flue gases. Coal-based thermal power plants are among the leading stationary industrial sources of mercury emissions worldwide, contributing to atmospheric deposition and subsequent bioaccumulation in aquatic food chains through methylmercury formation.
- Statement 3 - Incorrect: While mercury is undoubtedly a potent neurotoxin, regulatory and scientific bodies have established permissible exposure limits and reference dose levels for mercury. The existence of threshold-based safety standards and tolerable intake levels indicates that a defined reference point for safe exposure exists. Therefore, the claim that there is absolutely no known safe level of exposure to mercury is not accurate in the context of established toxicological standards.
Key Takeaway: Gold mining and coal-based thermal power plants are both established sources of mercury pollution - making Statements 1 and 2 correct. Statement 3 is incorrect as toxicological standards do define permissible reference levels for mercury exposure, making only two of the three statements correct.