HIGH IN THE ANDES MOUNTAINS IN PERU, a massive mine is slowly devouring the 400-year-old city of Cerro de Pasco. It has left a gaping hole, deep enough to hold the Empire State Building, in the center of the city. The giant pit covers an area equal to that of about 240 football fields. It continues to expand, eating away at the town around its rim and forcing people from their homes. The mine is also having a negative impact on residents' health--by poisoning the environment with dangerous chemicals.
Mining operations in Cerro de Pasco date back to the 1600s, when Spanish colonists discovered rich silver deposits there. Later, the area was mined for copper. Until the 1950s, miners used tunnels to extract these metals. Then the largest company mining the area switched to an open-pit mine to extract lead and zinc. The company dug a huge hole instead of underground shafts. It just so happened that deposits of the metals extend directly under the town.
As the mine expanded, workers dumped waste rock around the edges of its pit. The piles, laced with toxic lead and other harmful metals, have grown to the size of small hills. Many he just yards from houses and schools. Lead-laden dust blows everywhere in the city. Runoff from the mine has contaminated nearby lakes and rivers, turning them a sickly orange and leaving residents without safe drinking water.
A TOXIC METAL'S EFFECTS
Cecilia Chamorro, now 36, grew up in Cerro de Pasco, in a house just 6 meters (20 feet) from a rock pile. She didn't know how dangerous it could be until her son, Daniel--who also grew up near the dust mounds--had a blood test at age 2. "He had 20 micrograms per deciliter of lead in his blood," says Chamorro. That's four times the acceptable level identified by the U.S. Centers for Disease Control and Prevention, although no amount of lead is considered safe.
Lead is a neurotoxin, which means it affects the nervous system. It poses the greatest risk to children (see How Does Lead Harm the Body?, right). Low levels of lead can cause learning impairments and behavioral issues like attention-deficit/hyperactivity disorder (ADHD). Daniel, who is now 12, and his sister, Araseli, 8, both have learning disabilities. High levels of lead can cause convulsions and even death.
A TOWN IN NEED OF HELP
In places where lead is found in dust or soil, children are even more at risk because they play and crawl on the floor or ground. They ingest lead-bearing dust or soil when they put objects or their hands into their mouths, says Bruce Lanphear, a pediatrician and researcher at Simon Fraser University in Canada who studies the effects of lead on children.
Lead levels in Cerro de Pasco's children have been tracked since 1996. In 2012, the Peruvian Health Ministry found that about 2,000 kids--more than half of those tested--had lead levels higher than twice the acceptable level. To draw attention to their plight, residents of Cerro de Pasco undertook a two-week-long march last September. They trudged over the mountains to Lima, Peru's capital, 240 kilometers (150 miles) away. Soon after, the government announced plans to build a hospital that would provide testing and treatment for lead poisoning.
Similar measures were promised before but never carried out, In 2008, a local congresswoman even managed to pass a law mandating the entire town be moved a safer distance from the mine. But the relocation never happened, because no one could settle on who should foot the bill. An American company owned the mine for more than half of the past century, then the Peruvian government, and most recently a Peruvian company. It's difficult to say who should be held responsible for the lead poisoning.
LEAD CLOSER TO HOME
The problem isn't isolated to places like Cerro de Pasco. In 2015, the city of Flint, Michigan, brought to light problems with lead contamination in the U.S. The year before, the town had switched its water supply to the Flint River. But officials failed to treat the corrosive (chemically damaging) water, which caused lead to leach from old pipes and exposed residents to unsafe levels of the metal. Flint made headlines nationwide, but Lanphear says it is just the latest of many similar cases in the U.S. (Read more about the Flint water crisis in the 4/18/16 issue of Science World.)
Children are also routinely exposed to lead in homes and contaminated soil in other places around the U.S. Lead in paints and gasoline wasn't prohibited in the U.S. until the 1970s. According to historian David Rosner of Columbia University in New York, lead industry executives knew how dangerous their product could be as far back as the early 1900s. But they did little to phase out its use, which would have gone against their business interests. "Now it's 2016, and we're paying the price, and we're still arguing about whether it's too expensive to clean up this mess," Rosner says.
Preventing lead exposure and the health problems related to it would save money in the long run, says Lanphear. "Too often, we put profit over people's health," he adds. In Cerro de Pasco, Chamorro and other parents hope that will change. "We're going to keep fighting for our children," Chamorro says. "And not just the children. This is a problem that affects everyone."
What do residents of Flint, Michigan, have in common with people living in Cerro de Pasco, Peru? Explain your answer using evidence from the text.
HOW DOES LEAD HARM THE BODY?
No amount of lead exposure is considered safe. Ingesting lead can severely affect children's mental and physical development. Children under the age of 6 are particularly vulnerable to lead's toxic effects because the brain is growing rapidly. Lead is also dangerous because it accumulates in growing bones, making it difficult or impossible to remove from the body. As lead levels increase, so do the severity and range of problems.
NERVOUS SYSTEM: Lead attacks nerves and the brain, causing difficulties with attention, learning, and behavior, as well as hearing loss. In high enough doses, lead can cause convulsions, coma, and even death.
BONES: Lead accumulates in bones and stunts their growth.
KIDNEYS: Lead damages kidneys, the organs that filter waste products from the blood. In adults, long-term exposure to lead can cause kidney damage and chronic kidney failure.
Lead can cause abdominal pain, constipation, nausea, and lack of appetite.
NEED A LOWER READING LEVEL?
Go to scholastic.com/scienceworld to access a version of this article with a lower reading level.
FEATURED NGSS LESSON PLAN OBJECTIVE
Students will gather evidence from two articles that discuss the causes and effects of lead contamination in two cities, and then form an argument about how well the resulting health crisis was handled in each location.
COMMON CORE STATE STANDARDS READING: INFORMATIONAL TEXT
STANDARDS: 9. Analyze how two or more texts address similar themes or topics to build knowledge.
(1) BEFORE-READING DISCUSSION
Ask students: What are some ways officials protect people from exposure to hazardous chemicals? (cleaning and testing water supplies; limiting the amount of pollution released into the environment; requiring that industries safely dispose of chemicals)
(2) READ THE ARTICLE AND GATHER EVIDENCE
Have students open their magazines to page 14. Read the Essential Question out loud. Instruct students to think about the question as they read the article silently. After reading, discuss whether a similar situation could happen in the U.S. Ask them to support their answers by gathering evidence from the text.
(3) COMPARE TWO TEXTS
Access the April 18, 2016, issue of Science World by visiting scholastic, com/scienceworld. Open the issue to page 18 and read the article titled "Troubled Waters" aloud as a class. Compare how the authors of the two articles addressed the topic of lead contamination. What information is included in both articles? Why do you think this information was included?
(4) FORM AN ARGUMENT
Hand out the skills sheet "Compare the Crises" found at scholastic.com/scienceworld. Have students use it to research the causes and effects of lead contamination in "Swallowed by a Mine" and "Troubled Waters." Students will then use the information to compare and contrast the two lead crises and present arguments to the class about how well they think they were handled in each city. As an extension activity, have students present their arguments, along with supporting evidence from the texts, to the class.
(5) AFTER-READING DISCUSSION
Ask students if there should be worldwide regulations about how environmental hazards are handled. Why or why not?
NGSS ASSESSMENT PACKAGE
Each skills sheet integrates a science and engineering practice, a crosscutting concept, and a core idea to form a comprehensive NGSS lesson.
FEATURED LESSON CHEMISTRY:
Compare the Crises Students will read a paired text and then craft arguments comparing and contrasting how well two different cities dealt with lead-contamination problems.
PRACTICE: Engaging in Argument From Evidence
CROSSCUTTING CONCEPT: Cause and Effect
CORE IDEA: ETS1.B: Developing Possible Solutions
Students will obtain information about different lead sources found in the home that are health risks.
PRACTICE: Obtaining, Evaluating, and Communicating Information CROSSCUTTING CONCEPT: Influence of Science, Engineering, and Technology on Society and the Natural World CORE IDEA: ESS3.C: Human Impacts on Earth Systems
Students will carry out an experiment to learn how chemical reactions in a battery containing lead convert one form of energy to another.
PRACTICE: Planning and Carrying Out Investigations
CROSSCUTTING CONCEPT: Systems and System Models
CORE IDEA: PS3.D: Energy in Chemical Processes
Sources of Lead Students will analyze and interpret data about the amount of lead mined as a natural resource around the world.
PRACTICE: Analyzing and Interpreting Data
CROSSCUTTING CONCEPT: Scale, Proportion, and Quantity
CORE IDEA: ESS3.A: Natural Resources
CHECK FOR UNDERSTANDING
DIRECTIONS: Answer the following questions in complete sentences.
1. Describe how miners collect metals in an open pit mine.--
2. What scientific evidence shows that children in Cerro de Pasco, Peru, are suffering from lead poisoning?--
3. What is a neurotoxin?--
4. According to the article, why are children more likely to ingest lead than adults are?--
5. Explain why the residents of Cerro de Pasco were never relocated.--
CHECK FOR UNDERSTANDING
1. To remove rock, miners dig a large hole instead of underground shafts.
2. Blood tests have shown that 2,000 children in the city of Cerro de Pasco have lead levels higher than twice the acceptable level, as per the CDC.
3. A neurotoxin is a chemical that affects the body's nervous system.
4. They crawl and play on the ground and place objects or their hands, which may be carrying lead-bearing dust, into their mouths.
5. Officials couldn't agree on who should pay for the relocation. Over the years, the mine has been owned by several companies and even the Peruvian government.
Caption: MISSING CITY: A huge hole sits where the historic center of Cerro de Pasco once stood.
KIDS AT RISK: Many of the city's children suffer from lead poisoning from the mine.
ESSENTIAL QUESTION: What effect has the lead mine in Cerro de Pasco, Peru, had on the health lot the city's residents?
Caption: MINE DANGERS
1 The enormous mine in Cerro de Pasco has eaten away a large portion of the city.
2 Lead from the mine has contaminated local rivers, making the water unsafe to drink.
3 Children play near piles of lead-laden rock removed from the mine.