Lead in our Lives

Chapter 23. Lead in our Lives

Biology Connections with Assessment
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You must read each slide, and complete the question on the slide, before proceeding to the next one.
Uses of lead range from deadly bullets to stained glass windows in churches.

Read the article below. Then complete the comprehension questions that follow.

Lead is both useful and toxic to humans

Lead is an inexpensive metallic element that is durable, resistant to corrosion, and malleable. Unfortunately, it’s also a toxin that can enter our bodies in tiny quantities, accumulate in our tissues, and cause great harm—particularly to our nervous system. Through this combination of usefulness and toxicity, lead has both helped and poisoned humans for thousands of years. Let’s see how lead has been useful, as well as how it can adversely affect our bodies.

Bullets, pipes, paints, and gas

Humans have found countless uses for lead throughout history. Ancient Egyptians mixed lead into pottery glazes, and Romans used it to make water pipes. Lead is in the stained glass windows that have graced churches since medieval times, as well as in the moveable type of printing presses that promoted literacy and free expression.

Considering all the people killed by them, lead bullets have also had an enormous impact on history—though generally the result of damage done to the body, and not because of lead’s toxicity. The toxicity of lead bullets can be a serious problem for other animals, however. (See the section on “Lead & Condors” below.)

Most of the toxicity of lead to the systems of the human body has come from three sources: pipes, paints, and gasoline. Lead was a common component of all three a little more than a generation ago.

The practice of making water pipes from lead far outlasted the Roman Empire. Lead was still being used for pipes well into the 20th century, and lead-based solder to join copper pipes was still used in the 1980s. For hundreds of years humans were ingesting toxic lead particles along with the water they drank from these pipes.

Lead was in paint for a long time, too. As recently as the 1970s, house paints contained lead, and undercoats of paint in many homes, schools, and workplaces still do. This puts children and pets—who spend much of their time on the floor where paint dust and chips land—at particular risk. Lead was even breathed in from the air. Tetraethyl lead was added to gasoline from the 1920s until the 1970s. The dangers of toxic emission created by leaded gas caused its gradual reduction and eventual banning.

Lead Paint in Toys

Lead most recently made the news when poisonings were linked to contaminated toys manufactured in China and sold in the United States. In 2007, toy manufacturers recalled more than one-million toys because of lead paint contamination.

How lead acts in the body

Lead was once added to gasoline to improve performance, but it also put lead into the air.

The dangers of lead have long been in evidence. The Greek physician Nikander described lead poisoning 2300 years ago, and historians tell us that Roman aristocrats suffered from psychosis and infertility—both symptoms of lead poisoning. But how does lead wreak havoc when it enters our bodies?

Lead is carried by the blood to soft tissue and bone where it can be stored for many years. Exposure can be harmful to several organs— including kidneys—as well as the nervous system. Long-term exposure to lead can cause memory loss and learning impairment. Recent studies have linked early childhood exposure to behavioral problems and juvenile delinquency. Death can result from sustained exposure.

Many of lead’s toxic properties stem from its ability to mimic calcium, altering cellular processes. Even at low concentrations, lead interferes with the release of neurotransmitters (chemicals used by the nervous system to communicate with nearby cells), especially in the brain. Star-shaped cells, called astrocytes, can be impacted by lead as well. Astrocytes help repair scarring in the brain and spinal cord and provide nutrients to nervous tissue. This is why lead poisoning in high doses can result in brain hemorrhaging.

Lead also interferes with the protective sheath that insulates nerve cells in the central nervous system, and alters the integrity of the blood-brain barrier. This damage can lead to severe impairment, especially in children. Tots with lead poisoning might complain of stomachaches and exhibit hyperactivity, sleeping problems, or irritability. Because these symptoms mimic other conditions, lead poisoning is sometimes mistaken for a cold or the flu.

Getting the lead out of your life

Conservation groups and public health department campaigns continue to warn the public about lead pollution. Even though the metal is now banned in pipes, paint, and most gasoline, many of us who live, work, and go to school in older buildings can come into contact with lead, and lead-contaminated soil lines many streets and roadways.

What can you do to reduce your exposure to lead? If you have doubts about the safety of your home or workplace, have tests done on the water and paint. Most importantly, watch for the warning signs of lead poisoning, especially in children. The only way to diagnose lead poisoning is by having a blood test, but treatment shortly after exposure can sometimes help prevent severe damage.

Lead & Condors

Even birds bite the lead bullet. Research recently proved that condors and other endangered birds consume tiny bits of lead-based ammunition when scavenging the remains of animals killed by shotguns. Also, animals can mistake spent shotgun pellets on the ground for seeds and consume them. This is a big problem since the ammunition most recreational shooters fire from their guns remains in the countryside.

In the winter of 2010 three endangered California condors died from lead poisoning, bringing the total number of lead-related deaths since 1996 to 15—a hard hit, since there are only several hundred California condors alive today.

© 2015 WH Freeman and Company.

Answer the following questions to demonstrate your understanding of the article.

1.

The Romans constructed their out of lead. In fact, this practice continued long after the Romans, well into the 20th Century.

2
Correct. As the article points out, the Romans fashioned water pipes out of lead. Up until a generation ago, lead was still commonly used for piping in the modern world.
Try again. The article didn’t mention that particular example.
Incorrect. As the article points out, the Romans fashioned water pipes out of lead. Up until a generation ago, lead was still commonly used for piping in the modern world.

2.

Fill in the Blank:

Lead may harm the nervous system and key internal organs, including the , with long-term exposure possibly leading to complete renal failure.

2
Correct. Along with other vital internal organs, the kidneys can be adversely affected by even slight exposure to lead, including inhibiting proper excretion of waste products and filtration.
Try again. You have one attempt remaining. ("Renal failure" should provide you a hint.)
Incorrect. Along with other vital internal organs, the kidneys can be adversely affected by even slight exposure to lead, including inhibiting proper excretion of waste products and filtration.

3.

Lead exposure can adversely affect the release of ________________ from nerve cells, in turn affecting proper cell functioning and communication.

A.
B.
C.
D.
E.
2
Correct. Neurotransmitters are the chemicals released by neurons for communication between cells. Exposure to lead, even at low levels, can negatively affect the release of neurotransmitters, preventing communication and proper cell functioning.
Try again. You have one attempt remaining.
Incorrect. Neurotransmitters are the chemicals released by neurons for communication between cells. Exposure to lead, even at low levels, can negatively affect the release of neurotransmitters, preventing communication and proper cell functioning.

4.

True/False:

The only way to detect if lead has been absorbed and/or stored in the body is to examine a blood sample for the presence of lead.

Correct. Lead that has been absorbed into the body, either by breathing in lead dust or ingesting lead-contaminated material, can be detected by blood analysis.
No, this statement is True. Lead exposure can only be directly determined by blood analysis.

5.

Fill in the Blank:

A specialized, star-shaped cell found within the central nervous system called a(n) can be damaged by chronic exposure to lead. These cells are responsible for repairing scarring within the brain and spinal cord as well as proving nutrients to cells of the nervous system.

2
Great job! Astrocytes are found only within the central nervous system and play an important role in the maintenance of the brain and spinal cord.
Try again. The shape of the cell provides a clue to its name. You have one attempt remaining.
Incorrect. Astrocytes are found only within the central nervous system and play an important role in the maintenance of the brain and spinal cord.

6.

Buying a house is a big decision for anyone to pursue. Based on the information in the article, which of the following should be tested for lead before purchasing a house that was originally built in 1920 and last renovated in 1970?

A.
B.
C.
D.
E.
2
Good job! Older houses such as this may be contaminated with lead, including not-so-obvious sources such as soils surrounding a home, which may be contaminated with lead-based paint chips.
Try again. You have one attempt remaining.
Incorrect. The correct answer is “All of the above.” As the article points out, paint commonly contained lead well into the 20th century. So not only would you want to test interior and exterior walls, but also soils surrounding the home, where lead-containing paint chips might be found. Likewise, many pipes contained lead well into the 1970s and 80s, so drinking water should be tested, too.

7.

For 4 years, Lisa and her family lived in a home that was contaminated with lead paint. About 8 months ago, they moved into a brand new home that is completely lead-free. However, results of a recent blood test indicated that Lisa has elevated levels of lead in her blood, which has her parents very concerned.
What is a reasonable explanation for her blood test results?

A.
B.
C.
D.
E.
2
After exposure, blood can carry lead from bone and soft tissues, where it may be stored for years, to other parts of the body. Therefore, it may take some time for detectable levels of lead to enter the bloodstream from fatty tissue or bones.
Try again. You have one attempt remaining.
Incorrect. After lead exposure, blood can carry lead from bone and soft tissues, where it may be stored for years, to other parts of the body. Therefore, it may take some time for detectable levels of lead to enter the bloodstream from fatty tissue or bones.

8.

Which of the following are ways that lead can affect the central nervous system? Check ALL that apply.

interferes with proper release of neurotransmitters

impacts astrocytes that help repair nervous tissue

causes heightened brain activity and brain functioning

alters the integrity of the blood-brain barrier

damages the protective sheath that insulates nerve cells

triggers neurons to “fire” more rapidly

Correct. As the article points out, lead poisoning can affect proper cell functioning and lead to extensive damage of the central nervous system.
Incorrect. All of the items are ways that lead can affect the central nervous system, EXCEPT causing heightened brain activity and causing neurons to fire more rapidly. In fact, lead can greatly impede proper communication between cells, particularly in the brain.

9.

The article notes that California condors are susceptible to lead poisoning as the result of ingesting lead-based ammunition when scavenging remains of animals killed by shotguns. What is a reasonable compromise hunters could make to prevent unintended deaths of these endangered birds?

A.
B.
C.
D.
E.
2
Good job. This not only would be effective, but is an excellent compromise between hunters and conservation groups.
Try again. You have one attempt remaining.
Incorrect. The most amicable solution here would be for hunters to replace their lead-based bullets with other types of ammunition.

10.

The US Centers for Disease Control and Prevention (CDC) recommends that, if any child (between the ages of 1 and 5) has a blood test indicating lead levels equal to/greater than 45 micrograms per deciliter of blood, he/she should be treated with chelation, a procedure that lowers blood lead levels.
Using that knowledge, review the graph above, which shows the blood lead level of a 4-year-old child recorded over a period of several months. (You may click the graph to expand and view in a larger window.)
Based on the data shown, did this child need to have chelation treatment at any point?

A.
B.
C.
D.
E.
2
Yes. As the graph indicates, the child’s blood lead levels were hovering near 50 micrograms/deciliter in late July, warranting chelation treatment.
Try again. Take another look at the graph. You have one attempt remaining.
Incorrect. The graph indicates that the child’s blood lead levels were hovering near 50 micrograms/deciliter in late July, warranting chelation treatment.

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