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?

Let's examine the statements regarding mercury pollution:

1. Gold mining activity is a source of mercury pollution in the world. This statement is correct. Artisanal and small-scale gold mining (ASGM) is a significant global source of mercury pollution. Miners often use mercury to amalgamate gold from ore, which is then burned off, releasing highly toxic mercury vapor into the atmosphere and liquid mercury into water bodies.

2. Coal-based thermal power plants cause mercury pollution. This statement is correct. Coal naturally contains trace amounts of mercury. When coal is burned in thermal power plants for electricity generation, this mercury is released into the atmosphere as a gaseous pollutant, which can then be deposited in ecosystems and bioaccumulate in the food chain.

3. There is no known safe level of exposure to mercury. This statement is correct. Mercury, particularly its organic form, methylmercury, is a potent neurotoxin. Scientific and health organizations (like the WHO) generally advise that there is no safe threshold for mercury exposure, especially for vulnerable populations, given its severe and irreversible health effects on the nervous system, kidneys, and developing fetuses.

All three statements are correct.