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?

1. Statement 1 is correct. Artisanal and small-scale gold mining activity is a major global source of mercury pollution, as mercury is often used in the process to extract gold from ore, leading to environmental release. 2. Statement 2 is correct. Coal-based thermal power plants are significant contributors to mercury pollution because coal naturally contains mercury, which is released into the atmosphere during combustion. 3. Statement 3 is generally considered incorrect in a regulatory context. While mercury is highly toxic and exposure should be minimized, health organizations and regulatory bodies (like WHO, EPA) have established reference doses or tolerable daily intake levels, implying levels below which significant health risks are not expected. Thus, claiming there is absolutely no known safe level of exposure to mercury is debatable, although it's true that any exposure carries some risk, especially for vulnerable populations. 4. Therefore, statements 1 and 2 are correct. This means two of the statements given are correct.