Toxicology and Exposure to Bisphenol A (BPA)

11.1 Toxicology and Exposure to Bisphenol A (BPA)

Introduction:

Bisphenol A (BPA) is a chemical that is used in the manufacture of plastics. It has been brought to the public’s attention due to its prevalence in such items as water bottles, baby bottles, and the linings of food cans. It is known to be an estrogen mimic and human exposure appears to be widespread. In this exercise, we will look at the amount of BPA detected in urine samples in a study conducted by the Centers for Disease Control (CDC).

DATA SETS:

All data come from the Centers for Disease Control, Fourth National Report on Human Exposure to Environmental Chamicals, February 2015.

Studies of BPA in urine of human test subjects indicate nearly universal presence, suggesting that exposure is widespread. In this exercise, we will look at the mean concentrations measured in micrograms/liter. We will begin by examining the data for all the years available (in two-year increments) by age group. To do so, select “BPA Concentration by Age Class” from the drop-down menu.

Question

1. Which age group registered the highest concentration overall in this study?

Ages 6–11 during the 2003–2004 study period.

Ages 12–19 during the 2003–2004 study period.

Ages 12–19 during the 2009–2010 study period.

Ages 6–11 during the 2005–2006 study period.

Correct!

Incorrect.

Question

2. Does the graph indicate an overall trend in concentrations of BPA over time?

Yes, BPA concentrations appear to be decreasing for the youngest age class, but not for the others.

Yes, BPA concentrations are decreasing over time for all age classes.

BPA concentrations are only decreasing during the 2007–2008 and 2009–2010 time periods.

It appears that for the most part the concentrations are stable over time.

Correct!

Incorrect.

Question

3. Is there one age class that has a consistently lower concentration of BPA than the others?

Yes, the 12- to 19-year age class is consistently lower than the others.

Yes, the 6- to 11-year age class is consistently lower than the others.

Yes, 20 and over age class is lower than the others in every year of the study.

There is not enough information presented in the graph to answer this question.

Correct!

Incorrect.

Question

4. Which of the following is a plausible explanation for the changes in concentrations over time?

Humans tend to bioaccumulate BPA, which means that over time the concentration in the body increases.

BPA has become more prevalent in the environment, indicating higher exposure rates year after year.

Active metabolism during teenage years processes BPA so that concentrations are at their lowest at that time.

Environmental exposure to BPA seems to have decreased over the course of the study period.

Correct!

Incorrect.

Question

5. Compare the average concentration across all study years for the youngest age class and the middle age class. (Hint: Add all values for the youngest age class and divide by the total number of values to find the average. Do the same for the middle age class. Compare the values.)

The average for the youngest age class is far higher than that of the middle age class.

The average for the middle age class is significantly lower than that of youngest age class.

Although the differences seem significant for certain individual years, the two age groups are nearly equivalent when averaged across the study period.

The average for the middle age class is nearly two times higher than that of the youngest age class.

Correct!

Incorrect.

Question

6. Now we will compare concentrations across gender. To do so, select “BPA Concentration by Gender” from the drop-down menu. There is an obvious difference between the concentrations measured in men than in women. What is a plausible explanation for this observation?

Men may process BPA slower than women.

Men may typically engage in activities that entail greater exposure to BPA.

When men and women are exposed to the same amount of BPA, men may accumulate more of it.

All of the above are plausible explanations and it would take more research to discover which one is the best explanation.

Correct!

Partially correct.

Question

7. Now let’s look at ethnicity by selecting “BPA Concentration by Ethnic Group” from the drop- down menu. Is there any noticeable difference between ethnic groups in this study?

No. Although the BPA level in non-Hispanic blacks is very high in the 2003–2004 study year, it is more or less at the level of the other ethnic groups for the rest of the study period.

Yes, the concentration in non-Hispanic blacks is highest.

Yes. Non-Hispanic whites have the lowest concentration for half of the study years.

Yes. Mexican Americans always have the highest concentration of BPA for the study period.

Correct!

Incorrect.

Question

8. What percentage higher is the average concentration for the ethnic group with the highest BPA concentration than the average concentration for the next highest ethnic group? (Hint: To determine the percent difference, first find the difference between the two numbers and then divide by the mean of the numbers, or the average of the numbers. Finally, multiply times 100 to get percent. Remember to find the average across all years for each ethnic group before calculating percent difference!)

The average concentration of BPA detected in non-Hispanic blacks was 49% higher than in Mexican Americans.

The average concentration of BPA detected in non-Hispanic blacks was 39% higher than in Mexican Americans.

The average concentration of BPA detected in non-Hispanic blacks was 33% higher than in Mexican Americans.

The average concentration of BPA detected in non-Hispanic blacks was 12% higher than in Mexican Americans.

Correct!

Incorrect.

Question

9. Scientific studies indicate that BPA does not bioaccumulate in humans, which suggests that if most human study subjects have a measurable concentration in their urine, then _____.

they have consistent and recent exposure to BPA

they have been exposed at some point in their lives though it may not be recent

they will always carry that BPA with them and possibly pass it onto their offspring

it was likely passed on from their own parents

Correct!

Incorrect.

Question

10. Evidence suggests that lab animals show reproduction-related health effects resulting from exposure to BPA. However the effects on humans remain uncertain. Common sources of BPA include plastics, including water bottles, and the linings of food cans. If you are concerned about exposure to BPA, which of the following would help to reduce your exposure?

Being aware of packaging materials and being an informed consumer.

Avoiding bottled water sold in containers that are made with BPA.

Pushing for legislation to eliminate or minimize exposure to this chemical.

All of the above

Correct!

Partially correct.

true

Chapter 11. Toxicology and Exposure to Bisphenol A (BPA)

11.1 Toxicology and Exposure to Bisphenol A (BPA)

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