Background: Many different chemical substances cause cancer. Dozens of chemicals in tobacco smoke, including nicotine, have been shown to cause cancer ( Figure below ). In fact, tobacco smoke is one of the main sources of chemical carcinogens. Smoking tobacco increases the risk of cancer of the lung, mouth, throat, and bladder. Using smokeless tobacco can also cause cancer. Other chemicals that cause cancer include asbestos, formaldehyde, benzene, cadmium, and nickel.

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend was at a higher risk for developing cancer?
Answer: Tom

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend was at a lower risk for developing cancer?
Answer: Randy

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend was exposed more to one of the main sources of chemical carcinogens?
Answer: Tom

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend was exposed less to one of the main sources of chemical carcinogens?
Answer: Randy

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend had an increased risk of developing cancer of the lung?
Answer: Tom

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend had a lower risk of developing cancer of the lung?
Answer: Randy

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend had a lower risk of developing cancer of the mouth?
Answer: Randy

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend had a higher risk of developing cancer of the mouth?
Answer: Tom

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend had a higher risk of developing cancer of the throat?
Answer: Tom

Situation: Two friends met after 20 years. Tom had been smoking tobacco all these years and had some health problems related to that, while Randy quit smoking 25 years ago.

Question: Which friend had a lower risk of developing cancer of the throat?
Answer: Randy

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady is more exposed to cancer?
Answer: Patty

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady is less exposed to cancer?
Answer: Julie

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady is less exposed chemical carcinogens?
Answer: Julie

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady is more exposed chemical carcinogens?
Answer: Patty

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady has a higher risk of getting lung cancer?
Answer: Patty

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady has a lower risk of getting lung cancer?
Answer: Julie

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady has a lower risk of getting mouth cancer?
Answer: Julie

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady has a higher risk of getting mouth cancer?
Answer: Patty

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady has a higher risk of getting throat cancer?
Answer: Patty

Situation: Two ladies sit in a coffee shop. Patty smokes three packs of cigarettes a day, but her good friend Julie, doesn't smoke. They are both 65 years old. They are enjoying a coffee.

Question: Which lady has a lower risk of getting throat cancer?
Answer: Julie