What’s in the Water? Lesson 2: Introduction to Emerging Contaminants
This lesson begins with a reading of a letter sent by the City of Pittsboro, NC to their residents. It reveals the presence of unregulated contaminants in their drinking water, including the emerging contaminant PFAS. After sharing their reactions and raising questions in class discussion, the students work in small groups to explore some common industrial contaminants in order to understand how/why certain compounds are regulated and others are not. After a brief lecture/introduction to the PFAS family of chemicals, the students will work in groups to explore the most common sources and pathways of PFAS chemicals in order to make predictions about origins and movement of PFAS around Pittsboro. At the end of the lesson, students will reflect on the types of information they will need in order to help the residents of Pittsboro decide how to handle the issue.
This activity has been used in an introductory-level university course in environmental science that enrolls both majors and non-majors, as well as a summer intensive science course for high school students, both in North Carolina where the unit is set. It could easily be adapted to other locations where PFAS contamination is present, as well as to geology or biology courses.
Skills and concepts that students must have mastered
Students should be familiar with water and contaminant cycling through natural environments, and should be able to distinguish between point source and nonpoint source contamination. They should be comfortable drawing and/or viewing maps/diagrams to illustrate the pathways of water and contamination in natural environments.
How the activity is situated in the course
This is the second instructional lesson of the "What's in the Water?" PFAS Contamination Unit". Prior to this lesson, students will have been introduced to the unit-long Community-Engaged Project, met the community partners to understand the local PFAS contamination situation and the community partner's needs, and studied the basic pathways that water and contaminants move through natural environments.
Content/concepts goals for this activity
1. Students will be able to define "emerging contaminant" in the context of drinking water
2. Students will be able to discuss the origins and general chemical composition of the PFAS family of chemicals
Higher order thinking skills goals for this activity
- Synthesizing information from multiple sources
- Evaluating the quality and relevance of sources of information
- Designing models to illustrate pathways and relationships
Other skills goals for this activity
- Convergent decision-making (coming to agreement on a rank-ordered list of possible answers using an evidence-based rationale)
Description and Teaching Materials
The lesson will open with a discussion about a letter addressed to Pittsboro residents in October 2019. The letter indicates that the chemicals being detected in the water are "emerging contaminants." Citizens are divided in their reactions to the letter. Many trust the information in the letter – the Town has confirmed that the drinking water "meets or exceeds" every State requirement, so there seems to be no need for alarm. On the other hand, other residents are alarmed by the unknown health effects of these chemicals in the water. They want to know more about this category of chemical, "emerging contaminants." The instructor will then guide students to consider the following big picture questions:
- What are emerging contaminants?
- What is the PFAS family of chemicals and why are they a concern?
Activity 1 (Uncovering Emerging Contaminants)
Next, students will work in small groups to unpack the concept of emerging contaminants. Each group will be assigned a pair of chemicals to explore (see below) . The goal is for students to get a sense of the types of chemicals that are regulated vs those that are not. Students could produce a T-chart or other visual to represent their findings. The class will share and come to a consensus about the concept of emerging contaminants. Time estimate: 20-25 minutes
The instructor should assign each group of students one contaminant from each category:
- Emerging contaminants: 1,4 Dioxane, Perchlorate, Dinitrotoluene (DNT), Linuron, Meprobamate, Phenytoin
- Well known contaminants: Fluoride, Nitrates, Lead, Arsenic, Mercury, Copper
Students' visual report should include the following information:
- Source(s) of contamination
- Prevalence (common geographic regions, concentrations, etc.)
- Known effects on wildlife
- Known effects on human health
- Government regulation
To help the students better understand the specific situation occurring in Pittsboro, the instructor will introduce PFAS as a family of chemicals. General uses, common applications, and general information about its prevalence should be shared. Instructors will find helpful information to prepare for the lecture in the Background Guide and/or the Instructor Slides.
Activity 2 (The PFAS Life Cycle)
The instructor will open a discussion around the following guiding question: How could Federal and/or state legislative bodies set regulations and/or restrictions on PFAS and other emerging chemicals in central NC? Where would they start? Lead the class through a brainstorming session to consider the "subjects' of regulation – specific industries that produce/use PFAS, water treatment facilities that could purify the water, households that purchase and use products containing chemicals, landfills, etc. This discussion should provide an opportunity to talk about some of the sources and pathways of emerging chemicals, focused on the PFAS chemical family. This could be done as a whole class or in small groups (see teaching notes for suggested procedures). Time estimate: 15-30 minutes depending on scaffolding/degree of independence.
The instructor will close the lesson by guiding the students through a discussion to synthesize their new knowledge and reflect upon next steps. The following questions could be used to guide the discussion:
- What other information do we need to help the residents of Pittsboro decide how best to handle the situation with their water supply?
- What other emerging contaminants exist? How can we keep track?
What's in the Water Lesson 2 Lesson Plan (Microsoft Word 2007 (.docx) 10kB Nov3 21)
What's in the Water Lesson 2: Instructor Slides (PowerPoint 2007 (.pptx) 585kB Nov3 21)
What's in the Water Lesson 2: Background Guide (Microsoft Word 2007 (.docx) 549kB Nov3 21)
Teaching Notes and Tips
For Activity 1, it may be helpful to provide examples of reputable sources for students to reference as they begin their research. Examples of helpful resources are linked under Resources.
For Activity 2, instructors should select a structure that best fits their goals. We suggest creating two groups that will work in a "fission/fusion" sequence. The first set of groups will work on ONE major source and/or pathway (e.g. Industry products). Once the group has collected sufficient information. Shuffle the students into new groups in which each primary source is represented by one or two students (ensure that all sources are represented at least once). The new groups will work together to map out a pathway for PFAS chemicals throughout the Urban Water Cycle. The instructor could provide scaffolding by giving students some/all of the source locations and transport pathways. References to assist students are linked under the References section, below. Instructors may also opt to show a model of the various sources and pathways, starting with something like the ones found in the EBC Emerging Contaminants Seminar presentation from Weston and Samson (Feb. 25, 2020), linked under the References section below and in the Background Guide).
For the closing reflection, the instructor could opt to have students write a personal, open-ended reflection in lieu of, or in addition to, whole class discussion. We provide the following sample prompt for personal reflection: Write a statement from the point of view of a Pittsboro resident based on what you know so far. You could write a reflection expressing your feelings about the water issue (what bothers you the most), your concerns about yourself and others in the community, or something else. In your opinion, what should happen next?
- Formative assessment throughout the lesson is recommended. As students/groups share their findings, the instructor should ask guiding questions to help them draw connections between their tasks and the broader picture. Instructors may also take advantage of the mini-lecture period and whole class discussion to address misconceptions or gaps in understanding.
- At the conclusion of the lesson, instructors may opt to informally assess students' reflections by providing follow-up questions, noting areas where students could add supportive details or evidence, etc. Instructors could encourage students to look back at these reflections throughout the unit and monitor how their ideas change as they learn more.
- Ultimately, new or revised understandings from all lessons in the unit should be reflected by student answers to the Benchmarking Activity completed at the conclusion of the unit, which can be used for summative assessment purposes.
References and Resources
Activity 1 Resources for Students
- Emerging Contaminants and Federal Facility Contaminants of Concern, https://www.epa.gov/fedfac/emerging-contaminants-and-federal-facility-contaminants-concern
- Common Waterborne Contaminants, https://www.wqa.org/learn-about-water/common-contaminants
Activity 2 Resource for Instructors
- Model of PFAS Pathways, retrieved from the EBC Emerging Contaminant Seminar: The Lifecycle of PFAS - The Forever Chemical (slides 62-67) https://ebcne.org/wp-content/uploads/2020/03/Presentations-Emerging-Contaminants-Seminar-The-Life-Cycle-of-PFAS.pdf
Activity 2 Resources for Students
- Per- and Polyfluoroalkyl Substances (PFAS), https://www.epa.gov/pfas
- Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS), https://www.niehs.nih.gov/health/topics/agents/pfc/index.cfm
- Per- and Polyfluorinated Substances (PFAS) Factsheet, https://www.cdc.gov/biomonitoring/PFAS_FactSheet.html
Other materials in the "What's in the Water?" PFAS Contamination Unit":
- What's in the Water? Benchmarking Activity
- What's in the Water? Community Engagement Project
- What's in the Water? Lesson 1: Water Cycle and Watersheds
- What's in the Water? Lesson 3: The Economic Challenges of Clean Water
- What's in the Water? Lesson 4: Drinking Water & Environmental Justice
- What's in the Water? Lesson 5: The Health Effects of PFAS
- What's in the Water? Lesson 6: Drinking Water Quality Regulation in the U.S.