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: Linda lives in a run down house in downtown Detroit. The walls and floors are degraded, and were made with large amounts of asbestos. As a result, Linda comes into contact with asbestos frequently. Linda's cousin, Gerald, lives in a upper-class neighborhood of Detroit. His house was built recently, and as a result he never comes into contact with asbestos.

Question: Who is more likely to develop cancer?
Answer: Linda

Situation: Linda lives in a run down house in downtown Detroit. The walls and floors are degraded, and were made with large amounts of asbestos. As a result, Linda comes into contact with asbestos frequently. Linda's cousin, Gerald, lives in a upper-class neighborhood of Detroit. His house was built recently, and as a result he never comes into contact with asbestos.

Question: Who is less likely to develop cancer?
Answer: Gerald

Situation: Jamal is a chemist that washes his hands every day with benzene in order to remove excess chemicals. Because of this, he has a high level of contact with benzene on a regular basis. Jamal's son, Chester, is also a chemist. However, Chester washes his hands with water, and as a result he has no contact with benzene.

Question: Who is at a higher risk for developing cancer?
Answer: Jamal

Situation: Jamal is a chemist that washes his hands every day with benzene in order to remove excess chemicals. Because of this, he has a high level of contact with benzene on a regular basis. Jamal's son, Chester, is also a chemist. However, Chester washes his hands with water, and as a result he has no contact with benzene.

Question: Who is at a lower risk for developing cancer?
Answer: Chester

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a higher risk for getting lung cancer in the future?
Answer: Jim

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a lower risk for getting lung cancer in the future?
Answer: Robert

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a higher risk for getting mouth cancer in the future?
Answer: Jim

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a lower risk for getting mouth cancer in the future?
Answer: Robert

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a higher risk for getting throat cancer the future?
Answer: Jim

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a lower risk for getting throat cancer the future?
Answer: Robert

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a higher risk for getting bladder cancer the future?
Answer: Jim

Situation: Jim and Robert are identical twins both getting their yearly physical check ups at the doctor's office.  They are trying to figure out if they are at risk for any future health problems. Both of them consume the same diet and exercise the same amount, and were both raised in the exact same environment. But, Jim has smoked tobacco frequently for several years and Robert has never smoked tobacco in his life.

Question: Who is at a lower risk for getting bladder cancer the future?
Answer: Robert