What are considered "class A" carcinogens?

"Class A" carcinogens are defined as substances that are known to cause cancer in humans. This classification is based on sufficient evidence from epidemiological studies or animal studies demonstrating that exposure to these substances is directly linked to an increased risk of cancerous outcomes. The designation is part of a systematic evaluation process that assesses various agents for their potential carcinogenic risks.

In contrast, agents that are likely to be carcinogenic represent a different classification where the evidence is not as definitive. Non-carcinogenic compounds do not pose a cancer risk at any exposure level, and environmental pollutants without links to cancer would also fall outside this category. Therefore, option A precisely captures the essence of what constitutes "class A" carcinogens, aligning with established guidelines in carcinogen classification.