Which of the following statements about pollutants is false?

The statement that all pollutants are harmful to human health is not accurate. While many pollutants can have detrimental effects on human health, not all pollutants pose a direct threat. For instance, certain substances can be present in the environment in non-toxic forms or at levels that do not significantly impact health. Additionally, some pollutants may only be harmful under specific conditions or at certain concentrations.

In contrast, the other choices highlight true aspects of pollutants. Pollutants can indeed originate from natural sources, such as volcanic eruptions and forest fires, which release substances into the air and water. They can also accumulate in food chains, creating a phenomenon known as biomagnification, where the concentration of harmful substances increases at each trophic level. Furthermore, some pollutants are biodegradable and can be broken down by natural processes or organisms, thereby reducing their environmental impact over time.