Which substance is an example of a carcinogen?

• A. Benzene
• B. Carbon Monoxide
• C. Hydrogen Chloride
• D. Sulfur Dioxide

Answer: (A)

Carcinogens are substances known to cause cancer in humans or animals, which is why recognizing benzene as a risk is important in hazardous materials work. Benzene has well-established links to blood cancers, especially leukemia, and major health agencies classify it as a Group 1 carcinogen, meaning cancer in humans has been demonstrated. When benzene is metabolized in the body, it forms reactive compounds that can damage DNA in bone marrow cells and disrupt normal blood cell development, increasing cancer risk with sufficient exposure over time. That’s why controlling occupational exposure to benzene through ventilation, monitoring, and protective equipment is essential.

The other substances are hazardous for different reasons but aren’t classified as carcinogens. Carbon monoxide is an asphyxiant that blocks oxygen delivery in the body. Hydrogen chloride is a corrosive gas that can burn and irritate tissues. Sulfur dioxide is a respiratory irritant that can aggravate breathing problems. None of these have the same cancer-causing evidence as benzene, so benzene is the example of a carcinogen.