Unit 1: Use of Lead in the Environment and Health Impacts on Human Populations
In Unit 1, students engage in discussion of the historical use and resulting distribution of lead throughout the human environment. Activity 1.1 introduces the systems dynamics linking geology, human use, and human health through an introductory lesson. Class discussion is facilitated by an exercise exploring students' risks of childhood exposure to lead. In a "pre-assessment exercise" suitable for homework or in-class group activity, students hypothesize explanations for varied lead exposures among different populations over time based on their existing understanding of lead's dynamics in the environment. Activity 1.2 analyzes the evolution of regulations and policies to reduce lead exposures and examines a current international case study that showcases the lag in regulatory guidelines for many parts of the world. In Activity 1.3, students explore exposure routes, transport, and fate of lead in the human body.
After completing this unit, students will be able to:
- Describe the use and distribution of lead in the human environment.
- Develop hypotheses for understanding how human exposures to lead vary temporally and spatially.
- Identify gaps in international policies and programs that contribute to adverse health outcomes.
- Explain how lead is absorbed and distributed within humans and their children recognizing the human body as a system through which lead cycles.
- Apply a lead exposure model to evaluate the significance of various factors in predicting health outcomes in children.
Context for Use
This unit should be used as an introduction to the Lead in the Environment module. It can be taught in any course on urban environmental issues or public health or can be modified to fit a variety of Earth and environmental science or public policy courses. The activities included in this unit are appropriate for introductory-level college students or as the basis for more in-depth exploration and application by upper-level students.
Description and Teaching Materials
Activity 1.1 - Introduction to Lead in the Environment (50 minutes)
In preparation for the beginning of this module, students should read the following handout giving an overview of lead poisoning.
- Reading 1 (Microsoft Word 2007 (.docx) 107kB Mar9 17)
The activity is designed to have three components:
- A discussion and associated PowerPoint with included video (10 minutes),
- An activity to answer questions based off of a table either individually or in groups (10 minutes),
- And a class jeopardy game (30 minutes).
We chose lead as the topic of this module because it is toxic to everyone, leaves permanent damage, and the symptoms are difficult to recognize. Specifically, lead causes damage to the brain and nervous system; it is dangerous even in very small amounts, as lead builds up in your body over time. However, children under 6 are especially at risk because they are more likely to come into contact with lead via household dust and paint, and also because they absorb it more easily than adults. In pregnant women, lead is linked to miscarriages, premature birth, low birth weight, brain damage, and reduced growth in young children. Once lead enters your body, it is distributed similarly to other minerals and typically ends up in the bone, interfering with calcium absorption, thus hindering transmission of signals through neurocognitive pathways. In other words, every single message the brains wants to send out to move, act or think, requires the use of these pathways. When lead replaces calcium in the neurological system these messages can't get through.
Starting with a short talk and PowerPoint (PowerPoint 1.3MB Sep3 17) allows for students to understand in further detail some key elements about lead that they learned in their pre-class reading. Making this portion as interactive as possible through questions and discussion will benefit students' knowledge and set a precursor for communication for the duration of the class. The short video embedded in the PowerPoint (slide 2) gives a brief overview of lead uses and its history. Activity 1.1: Historical comparisons of elevated blood lead levels, also embedded in the PowerPoint (PowerPoint 1.3MB Sep3 17) (slide 3) is intended to be conducted as a pre-assessment and brainstorming exercise to help students identify the information they will need to be able to predict who is at risk for lead poisoning. The presentation is to be completed after Activity 1.
Once this portion of the class is complete, Jeopardy should be played using this PowerPoint (PowerPoint 2007 (.pptx) 526kB Sep3 17). This allows for students to test what they know in an encouraging and interactive setting. Be sure students engage in this activity. For large classes, students may work in small groups. If you are interested in holding a class primarily focused on communicating with one another, it would be best to cut down time for the PowerPoint and activity, while mainly focusing on Jeopardy.
After the Jeopardy game has finished, this question should be posed to the class. It allows students to reflect on what they have just learned and apply it to their everyday lives.
- Have you ever encountered health issues related to lead in either your education or the media prior to this course? Based on your prior knowledge and our class today, do you think lead safety should be included more or less in these areas?
Materials for Activity 1.1
- Activity 1.1 Presentation (PowerPoint 1.3MB Sep3 17)
- Activity 1.1 Jeopardy (PowerPoint 2007 (.pptx) 526kB Sep3 17)
- Activity 1.1: Historical comparisons of elevated blood lead levels (Microsoft Word 2007 (.docx) 123kB Mar9 17)
- Teacher Materials (Microsoft Word 2007 (.docx) 154kB Mar9 17)
Activity 1.2 - Case Study of Unregulated Lead Exposure (50 minutes)
Activity 1.2 explores the historical foundations of our understanding of lead toxicity and the regulatory policies that slowly came into being. This class also explores a current major epidemic of childhood lead poisoning in Nigeria in communities that have families mining for gold without any occupational protections in place.
Before class, students should read the following three articles:
- Plume, G. S., Durant, J. T., Morman, S. A., Neri, A., Wolf, R. E., Dooyema, C. A., . . . Brown, M. J. (2013). Linking geological and health sciences to assess childhood lead poisoning from artisanal gold mining in Nigeria. Environmental Health Perspectives, 121(6), 744-750.
- CDC (2013). Lead Poisoning Investigation in Northern Nigeria.
PDF version - Lead Poisoning Investigation in Northern Nigeria (Acrobat (PDF) 115kB Sep9 15)
- Lead Poisoning Crisis in the Zamfara State in Northern Nigeria, MSF (May, 2012)
URL for PDF version - Lead Poisoning Crisis in the Zamfara State in Northern Nigeria
This activity begins with a discussion for approximately 10 minutes. Use the Historical and Occupational Lead discussion questions (embedded in the Teacher Materials (Microsoft Word 2007 (.docx) 142kB Mar9 17)) to prepare for this.
After exploring the recurrent historical pattern in the first portion of the activity, show students a video clip on artisanal gold mining in Nigeria: Nigerian children suffering in lead poisoning crisis, from BBC (3 min).
Next, students will explore a recent occupational/environmental case of lead exposure from artisanal gold mining in Nigeria (25 minutes). The activity can be explained by following Activity 1.2 Instructions (embedded in the Teacher Materials (Microsoft Word 2007 (.docx) 142kB Mar9 17)). Students will need Student Materials: Interdisciplinary approaches to addressing lead poisoning in Zamfara, Nigeria (Microsoft Word 2007 (.docx) 85kB Mar9 17).
The activity concludes with a short discussion (approximately 5 minutes) of how these modern occupational exposures in developing countries are similar to and different from the historical cases discussed at the beginning of class.
- Student Materials: Interdisciplinary approaches to addressing lead poisoning in Zamfara, Nigeria (Microsoft Word 2007 (.docx) 85kB Mar9 17)
- Teacher Materials (Microsoft Word 2007 (.docx) 142kB Mar9 17)
Activity 1.3 - Predicting Impacts on Populations and Individuals (50 minutes)
Three sections form this activity. Begin with a short discussion on lead and the EPA model to prepare for the interactive activity that follows. We provide a resource to guide discussion embedded in the Teacher Materials (Microsoft Word 2007 (.docx) 795kB Mar9 17).
The second section is the use of the EPA model and should take approximately 25 minutes. Instructions on use of the EPA model are embedded in the Teacher Materials (Microsoft Word 2007 (.docx) 795kB Mar9 17). You should demonstrate on the EPA model various inputs and ways in which it can be used. During this time, students will observe the model and answer guided questions in the Activity 1.3 Student Materials (Microsoft Word 2007 (.docx) 95kB Mar9 17)
Remaining time should be spent in discussion about the exposure factors and quality of data that go into the model. In section 2, we provide 8 questions for discussion, embedded in the Teacher Materials (Microsoft Word 2007 (.docx) 795kB Mar9 17) and as a worksheet in the Activity 1.3 Student Materials (Microsoft Word 2007 (.docx) 95kB Mar9 17). Some of these questions address inputs used to run the model while other questions address data that are generated from the model. At the end of this session, highlight to the students that this activity focused on how exposure factors can influence the distribution of lead within an individual human, while in the next activity students will discuss how lead is distributed in the population as a whole.
- Activity 1.3 Student Materials (Microsoft Word 2007 (.docx) 95kB Mar9 17)
- Teacher Materials (Microsoft Word 2007 (.docx) 795kB Mar9 17)
- Screenshot Instructions of EPA Model (PowerPoint 2007 (.pptx) 695kB Mar9 17)
The homework assignment Evaluation of State Data is a preparation activity for the next activity. Students evaluate state level lead data and are asked to respond to questions. They will need the data set Lead Levels by State Data (Excel 2007 (.xlsx) 100kB Mar9 17) and worksheet Preparation Assignment: Evaluation of State Data (Microsoft Word 2007 (.docx) 97kB Mar9 17).
Teaching Notes and Tips
- Student Activity 1.1: Historical comparisons of elevated blood lead levels could additionally be assigned as homework after this class, by asking the students to re-examine and add to their initial answers after having heard the remainder of the Unit 1 Presentation and using the additional web-based resources at the bottom of the worksheet.
- Note that the mean blood lead levels provided in the table are estimates based upon available data and plausible exposures; a brief explanation of their derivation is provided in the discussion notes.
- Each of these activities could be conducted independently, or expanded into multiple class sessions, allowing for more in-class research/discussion of the independent assignments.
- We have provided an optional PowerPoint presentation that is a teaching tool for instructors interested in the role of occupational exposure to lead and the history of regulating lead exposure.
- Optional PowerPoint (PowerPoint 2007 (.pptx) 81kB Mar9 17)
- If your students are not accustomed to reading scientific articles, please provide them with How to Read a Scientific Article (Microsoft Word 2007 (.docx) 140kB Mar9 17)
- For faculty who are particularly interested in issues regarding international lead exposures, we encourage you to visit this article about Syrian refugees that may spark further conversations about the ramifications of lead poisoning.
Riva, M.A., Lafranconi, A., D'orso, M. I., Cesana, G. (2012). Lead Poisoning: Historical Aspects of a Paradigmatic "Occupational and Environmental Disease." Safety and Health at Work, 3(1), 11-6.
- To explore occupational risks today, this video shows ventilation systems, recycling, and personal protection used in making lead sheeting: Introduction to Lead Manufacture, a YouTube video.
- The collective discussions and analysis of the EPA model are difficult to evaluate at an individual level. This particular discussion often finds students bringing very different levels of experience to the class. This discussion may be most valuable for students who have had no prior experience thinking about social determinants of health (race, ethnicity, poverty, etc.), and very straightforward for students who have spent years applying these concepts into academic practice. An assessment at this stage is not likely to evaluate individuals fairly; therefore, it is not a successful tool for assessing individual student learning on this topic.
This rubric is to be used for evaluation of student work in Activity 1. It is not meant to grade their preexisting knowledge of lead in the Jeopardy game.
- Activity 1.1 Rubric (Microsoft Word 2007 (.docx) 119kB Mar9 17)
- Evaluation of State Data Rubric (Microsoft Word 2007 (.docx) 88kB Mar9 17)
References and Resources
For further information on systems thinking to use as a reference point throughout the module, the following article can be utilized.
- Cash, D. W., Adger, w. N., Berkes, F., Garden, P., Lebel, L., Olsson, P., Pritchard, L., Young, O. (2006). Scale and Cross-Scale Dynamics: Governance and Information in a Multilevel World. Ecology and Society, 11(2): 8.
Other resources for the module and the first three classes are below:
- CDC (1994). Blood Lead Levels - United States, 1988-1991
- CDC (2013). Blood Lead Levels in Children Aged 1–5 Years — United States, 1999–2010
- CDC (2015). CDC's National Surveillance Data
- Smith, D. R. & Flegal, A. R. (1992). The public health implications of humans' natural levels of lead. Am J Public Health, 82(11): 1565–1566.
- Michele Augusto Rive, Alessandra Lafranconi, Marco Italo D'orso, Giancarlo Cesana, (2012). Lead Poisoning: Historical Aspects of a Paradigmatic Occupational and Environmental Disease. Review. Safety and Health at Work 2012;3:11-6. http://dx.doi.org/10.5491/SHAW.2012.3.1.11.
- How Stuff Works, (2009). History of Lead
- 3 min BCC video Nigerian children suffering in lead poisoning crisis
- Geoffrey S. Plumlee, James T. Durant, Suzette A. Morman, Antonio Neri,2Ruth E. Wolf, Carrie A. Dooyema, Philip L. Hageman, Heather A. Lowers, Gregory L. Fernette, Gregory P. Meeker, William M. Benzel, Rhonda L. Driscoll, Cyrus J. Berry, James G. Crock, Harland L. Goldstein, Monique Adams, Casey L. Bartrem, Simba Tirima, Behrooz Behbod, Ian von Lindern, and Mary Jean Brown. 2013. Linking Geological and Health Sciences to Assess Childhood Lead Poisoning from Artisanal Gold Mining in Nigeria. Environ Health Prospect, 121:744–750 (2013).
- Overbeek, O. (2012). Lead poisoning crisis in Zamfara State, Northern Nigeria - short web page summary with link to full 4-page report with additional information and photos.
- World Health Organization: Nigeria: mass lead poisoning from mining activities, Zamfara State - Update 1 - short summary of situation and partnership with CDC and Nigerian Department of Health
- Dooyema, C. A., Neri, A., Lo, Y., Durant, J., Dargan, P., Swarhout, T., Biya, O., Gidado, S. O., Haladu, S., Sani-Gwarzo, N., Nguku, P. M., Akan, H., Idris, S., Bashir, A. M., Brown, M. J. (2010). Outbreak of Fatal Childhood Lead Poisoning Related to Artisanal Gold Mining in Northwestern Nigeria Environmental Health Perspectives.
- Schmidt, C. W. (2013). Unsafe Harbor? Elevated Blood Lead Levels in Refugee Children. Environmental Health Perspectives 121, A190-A195.