What defines a carcinogen?

A carcinogen is specifically defined as a substance that is known to cause cancer in living tissue. This can include a range of compounds and agents that can lead to the development of cancer through various mechanisms, such as causing mutations in DNA or promoting uncontrolled cell division.

The identification of a substance as a carcinogen often relies on extensive research, including epidemiological studies and laboratory testing, which demonstrate a clear link between the exposure to the substance and an increased incidence of cancer. It's important for public health and safety regulations to accurately identify and manage exposure to carcinogens to reduce the risk of cancer in affected populations.

The other options, while related to health hazards, do not accurately capture the specific nature of carcinogens. Substances that cause skin irritation, accelerate aging, or lead to respiratory diseases are important health concerns, but they fall under different categories of toxicological hazards rather than being classified as carcinogens.