Chemical carcinogens present in smoke have been indentified as a major casue of

Options

A. Lung cancer
B. Liver cancer
C. oral cancer
D. None of these

Answer

### Step-by-Step Solution:

1. **Understanding Chemical Carcinogens**:
- Chemical carcinogens are substances that can lead to cancer by causing changes in cellular DNA. They can be found in various sources, including smoke.

2. **Identifying the Source**:
- In the context of this question, we focus on tobacco smoke as the primary source of chemical carcinogens.

3. **Composition of Tobacco Smoke**:
- Tobacco smoke contains over 4000 different chemicals. Among these, approximately 70 are identified as carcinogens, meaning they have the potential to promote cancer.

4. **Impact of Carcinogens**:
- When individuals are exposed to these carcinogenic chemicals, either through active smoking or passive (secondhand) smoking, their risk of developing certain types of cancer increases significantly.

5. **Major Cancer Associated with Tobacco Smoke**:
- The most significant type of cancer associated with tobacco smoke is lung cancer. The presence of chemical carcinogens in tobacco smoke is a major cause of lung cancer.

6. **Exclusion of Other Cancer Types**:
- While other types of cancer such as liver cancer and oral cancer exist, they are not primarily caused by tobacco smoke. Liver cancer is often linked to chronic infections (like Hepatitis), and oral cancer can be associated with tobacco and alcohol use, but the question specifically asks about the carcinogens in smoke.

7. **Conclusion**:
- Therefore, the correct answer to the question is that chemical carcinogens present in smoke are a major cause of lung cancer.