Activity: Processed Meat and Smoking as Carcinogens

Learning Objective:

Students will make judgments and draw appropriate conclusions based on the quantitative analysis of data presented from different sources. Students will also evaluate important assumptions in estimation and data analysis. Students will quantitatively interpret information from the media.

Background:

The World Health Organization has declared processed meat as a carcinogen. The article titled Processed meats rank alongside smoking as cancer causes- WHO by Sarah Boseley compares the cancerous effects of processed meat to those of smoking. In this activity, we will directly analyze the effects of these two carcinogens.

Activity:

1. Please read the article “Processed meats rank alongside smoking as cancer causes- WHO” by Sarah Boseley found at:

http://www.theguardian.com/society/2015/oct/26/bacon-ham-sausages-processed-meats-cancer-risk-smoking-says-who

2. The article states:

Bacon, ham and sausages rank alongside cigarettes as a major cause of cancer, the World Health Organisation has said, placing cured and processed meats in the same category as asbestos, alcohol, arsenic and tobacco.”

a) What questions does this statement raise?

b) Can you conclude from this statement that you are about as likely to get cancer eating meat as smoking? Or that smoking and eating processed meats increases your cancer risk by about the same amount?

3. The article also states:

The IARC’s experts concluded that each 50-gram (1.8-ounce) portion of processed meat eaten daily increased the risk of colorectal cancer by 18%.”

a) In [2] we see that the lifetime risk of someone developing colon cancer is 5%. Assuming this is about the rate of colon cancer in the population of people with little to no meat consumption, how does this rate increase by eating 50-grams of processed meat a day?

b) Let’s look a an extreme case. Suppose Joe is a heavy processed meat eater. According to [3], a hot dog frankfurter weighs 43 grams. Let us round this up to 50 grams to simplify things. Suppose Joe eats four hotdogs every day in his lifetime. What is the likelihood of Joe developing colon cancer in his lifetime?

c) In b), we rounded to simplify the math a bit. If we wanted to be perfectly accurate, is the chance of Joe developing colorectal cancer gotten in b) an overestimate or underestimate?

4. Let us now consider smoking as a carcinogen.

a) According to [5] we have that

Men who smoke are 23 times more likely to develop lung cancer. Women are 13 times more likely, compared to never smokers.”

Translate this into a percentage increase in the chance of a smoker developing lung cancer vs a nonsmoker.

b) How do these rates compare to processed meats?

c) Additionally, from [5] we learn “Nonsmokers have a 20 to 30 percent greater chance of developing lung cancer if they are exposed to secondhand smoke at home or work.”

How does this compare to processed meats?

d) Can we conclude that you are more likely to develop lung cancer as a smoker than colorectal cancer as a heavy meat eater?

e) Hold on a second! Even this is misleading! Even though we know the increase in the rate of smoking, we still do not know what the total percentage of people who smoke develop lung cancer. According to [6], “fewer than 10 percent of lifelong smokers will get lung cancer”.

So, are you more likely to develop lung cancer as a smoker or colon cancer as a heavy processed meat eater?

f) According to [4], 210,828 cases of lung cancer were recorded in the US in 2010. The population of the US at the time was 314 million.

What percent of the population developed lung cancer that year?

g) What can you conclude about processed meats and smoking as carcinogens?

We note that [6] also statesPart of the problem of the misconception of real risks is the emphasis on smoking and lung cancer. The greater danger is from vascular diseases leading to heart attacks and stroke, which kill more smokers than all cancers combined. Toxins in the tobacco smoke cause inflammation and hardening in the arteries.So smoking is definitely always a bad idea!

5. What is the deal with the WHO ranking? According to WHO, to be a group 1 carcinogen (which is what cigarettes and processed meats are) there needs to be a “sufficient evidence of carcinogenicity in humans”.

a) What does this mean?

b) Can we deduce group 1 carcinogens are very carcinogenic?

6. What are possible flaws in our analysis?

Suggest Solutions:

2a) Some possible questions include:

What determines the category a carcinogen falls into?

How is the probability of developing cancer effected when exposed to these carcinogens?

How much exposure is necessary to affect these rates?

b) No to both questions. We need to know more on how these rankings are determined.

3a)

5*1.18= 5.9%

3b) Total grams = 50*5 = 250 grams

5*(1.18)^4 = 9.7%

3c) Since we rounded up Joe’s meat consumption, we overestimated this probability by a bit.

4a) 2300% for men, 1300% for women

4b) These are much larger increases in the rate of cancer than processed meats.

4c) Even as a second hand smoker, the rate increase in cancer is larger than eating an additional 50 grams of processed meat a day.

4d) Although we know smoking increases our lung cancer rate a lot more than a nonsmoker, this does not give us any information on how likely we are to develop lung cancer. e) explains this further.

4e) The rates are about the same!

4f) .210 million/ 314 million = .00067 = .067%

4g) Less than .067% of Americans develop lung cancer. Yet, if you are a smoker, this jump dramatically to 10%. This is a very large increase. On the other hand, heavy consumers of processed meat also have about a 10% chance of developing colon cancer. However, this is not as significant of an increase from the base 5%.

5a) Being a group 1 carcinogen means there is a heavily backed scientific link between the carcinogen and the increase rate in cancer. However, this does not say anything about how large of a increase this is.

b) No. We can just deduce there is a large correlation between cancer and the carcinogen.

Downloadable Content: 

Word Document: meat and smoking as carcinogens

Sources:

1. http://www.theguardian.com/society/2015/oct/26/bacon-ham-sausages-processed-meats-cancer-risk-smoking-says-who

2. http://www.cancer.org/cancer/news/news/world-health-organization-says-processed-meat-causes-cancer

3. http://www.caloriecount.com

4. http://www.cdc.gov/cancer/lung/statistics

5. http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/lung-cancer/learn-about-lung-cancer/lung-cancer-fact-sheet.html

6. http://www.livescience.com/3093-smoking-myths-examined.html

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