Which statement best describes a pollutant?

• A. A pollutant is a substance released into the environment with harmful impacts
• B. A hazard is any chemical that can be harmful
• C. Something immune to hazards
• D. A toxin with no health effects

Answer: (A)

Pollutants are substances released into the environment that cause harmful effects to living things or ecosystems. This description captures both the fact that the substance ends up in the environment and that its presence leads to adverse outcomes, which is the essence of pollution. The other ideas don’t fit as well: a hazard refers to the potential to cause harm, not necessarily something released into the environment and causing harm, so it’s not the same as a pollutant. The notion of something immune to hazards is not meaningful in this context. And a toxin is inherently something that can cause health effects, so a toxin with no health effects contradicts what a toxin is.