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: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when they start discussing their smoking habits. Walter shares that he has regularly smoked a pack of cigarettes for the past ten years. Jesse says he only smoked a couple cigarettes during college while he was drinking and isn't a regular smoker.

Question: Which man is more likely to have lung cancer?
Answer: Walter

Situation: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when they start discussing their smoking habits. Walter shares that he has regularly smoked a pack of cigarettes for the past ten years. Jesse says he only smoked a couple cigarettes during college while he was drinking and isn't a regular smoker.

Question: Which man is less likely to have lung cancer?
Answer: Jesse

Situation: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when they start discussing their homes. Jesse says that he just recently discovered that the home he has been living in his entire life has had asbestos in it. Walter says that he has never lived in a home with asbestos.

Question: Is Jesse's chance of having cancer higher or lower than Walter's?
Answer: higher

Situation: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when they start discussing their homes. Jesse says that he just recently discovered that the home he has been living in his entire life has had asbestos in it. Walter says that he has never lived in a home with asbestos.

Question: Is Walter's chance of having cancer higher or lower than Jesse's?
Answer: lower

Situation: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when the subject of bad habits comes up. Jesse shares that he has always struggled with biting his nails and no matter what he seems to do he can't kick the habit. Walter's bad habit is that when he plays his weekly baseball game he will use chewing tobacco. He says he doesn't even particularly like the taste anymore, but once he gets to the park he has a craving for it.

Question: Which man's chance of having mouth cancer is higher?
Answer: Walter

Situation: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when the subject of bad habits comes up. Jesse shares that he has always struggled with biting his nails and no matter what he seems to do he can't kick the habit. Walter's bad habit is that when he plays his weekly baseball game he will use chewing tobacco. He says he doesn't even particularly like the taste anymore, but once he gets to the park he has a craving for it.

Question: Which man's chance of having mouth cancer is lower?
Answer: Jesse