Welcome to this installment of Quandary This! Chemistry in the News. In this article, we look at “forever chemicals,” also known as per- and polyfluororalkyl substances (PFAS).
Per- and polyfluoroalkyl substances, commonly known as PFAS, are a large group of synthetic chemicals that have become nearly ubiquitous in modern life. Found in everything from nonstick cookware and waterproof clothing to firefighting foams and food packaging, PFAS are valued for their durability and resistance to heat, water, and oil. These amazing properties have made them indispensable in many industries, but their use comes at a significant cost.
PFAS are often referred to as “forever chemicals” because of their persistence in the environment. Unlike many other materials, PFAS do not break down easily—they accumulate in soil, water, and living organisms over time. This persistence has led to widespread contamination, particularly in water supplies where PFAS-containing products have been heavily used.
The environmental and health risks associated with PFAS are well documented. Studies have linked exposure with a range of health issues, including thyroid disorders, immune system suppression, developmental problems in children and increased risk of cancer.
One of the most pressing challenges is removing PFAS from water. Conventional water treatment methods are largely ineffective against these chemicals—from the local water treatment facility to your refrigerator filter. Advanced techniques such as certain types of activated carbon filtration, ion exchange, and reverse osmosis systems can reduce PFAS levels, but they are costly and not available to everyone. Additionally, they transfer the problem by concentrating the chemicals in a filter rather than eliminating PFAS entirely.
Efforts to find cost-effective ways to eliminate or recycle PFAS, as well as to find more effective filtration methods, are ongoing. In the questions below, we will explore the landscape surrounding PFAS: its hazards, removal techniques, and possible paths for eliminating it.
Below are several types of questions that can be assigned to students at various levels of study.
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General Questions (appropriate for all students)
Challenge 1: Literature Research
Challenge 2: Essay Investigation
Challenge 3: In-Depth Analysis
Suggested Reading
General Questions
Answer the following questions, using the C&EN article “The challenges of going PFAS-free” or another source of your choice.
- Why are PFAS viewed as a problem? (Hint: there are several reasons.)
- Why did Chemours pay residents of Parkersburg a settlement in 2017?
- Why is it hard to replace PFAS refrigerants with non-fluoridated materials?
- Why are PFAS so hard to replace in firefighters’ turnout gear?
- PFAS are in many consumer products. What is one PFAS-containing product that you likely have in your possession that you have never actually touched?
Challenge 1: Literature Research
For Teaching Professionals: The following questions are intended to help students learn the critical skill of searching trusted sources of information, such as peer-reviewed literature, to find answers to specific questions. We encourage instructors to assign these questions to students enrolled in any introductory chemistry lab or lecture. By using literature to find the answers, students will learn to search and consume trusted scientific content with the intention of uncovering specific information. The grading is up to you, but we strongly recommend holding students accountable for presenting a clear answer to each question and accurately tying that answer to a properly cited source.
Prompt: For each of the following questions, provide an answer and cite the source of your information in ACS style. You can view citation examples and guidance in the ACS Style Quick Guide.
All the questions posed below can be answered in the journals, books, and news published by ACS Publications. While it is not the only reputable source of peer-reviewed information, the Suggested Reading list below may help you answer most, if not all, of these questions. Make sure you are logged in to your institution's library portal if you wish to search for additional sources on the ACS Publications website.
- What is considered a “long-chain” compound? How many carbons are typical?
- Name two methods of removing fluorine from a water source.
- Why is thermal regeneration considered not a feasible path for PFAS remediation?
- Is exposure to long-chain PFAS or short-chain PFAS more dangerous to a developing fetus?
- PFAS is known to exist in water. What other materials are you likely to encounter that would potentially expose you to PFAS?
Challenge 2: Essay Investigation
For Teaching Professionals: The following essay question is intended to help students go one step beyond simple question and answer research. This exercise encourages students not only to consider multidisciplinary exploration around a topic but also to develop written communication skills. As with other questions in this series, the grading is up to you, but we encourage you to help students develop a clear and concise style. Where possible, utilize chemical drawing utilities or neat handwritten molecules and mechanisms. The ideal answer should take no more than one sheet of paper. The ACS Guide to Scholarly Communication can be a great reference.
Prompt: Some evidence suggests that short-chained PFASs may disrupt endocrine systems more than long-chain PFAS. Discuss the benefits and drawbacks of the separation methods proposed in the suggested reading and propose one that you would suggest for implementation in a public water treatment facility.
Challenge 3: In-Depth Analysis
For Teaching Professionals: The following question will challenge students to uncover understanding around the business and legal implications of technological advance. This challenge is helpful for anyone who wants to build depth of thinking and understanding around the real-world circumstances involved in the application of technology. This may include business students, journalism students, and students interested in studying business or intellectual property law.
Prompt: Perfluoroalkyl substances are known as “forever chemicals” because they are notoriously difficult to remove from environments, and remediation pathway discovery is ongoing. One example is a patent for using cyclodextrins to remove PFAS cites several research articles, including several ACS Publications articles in The Journal of Physical Chemistry B and C by Karoyo et al. Given that patents are designed to secure ownership of novel discoveries and patent citations typically paint the landscape of “prior art” to demonstrate that their discovery is novel, what claim does the patent make that could be considered an advance upon the discoveries outlined in this article? (Hint: view the citation list to find the articles, and select one of them for your analysis.)
Suggested Reading
- Interactions of Aqueous Microdroplets and Mineral Particles Drive Fluorine-First Perfluoroalkyl Mineralization
- Thermal Regeneration of Spent Granular Activated Carbon Presents an Opportunity to Break the Forever PFAS Cycle
- Association between Prenatal Exposure to PFAS and Fetal Sex Hormones: Are the Short-Chain PFAS Safer?
- Are Geotextiles Silent Contributors of Ultrashort Chain PFASs to the Environment?
- Occurrence of Perfluoroalkyl and Polyfluoroalkyl Substances in Ice Cream, Instant Noodles, and Bubble Tea
- Determination of Legacy and Emerging Per- and Polyfluoroalkyl Substances (PFAS) in Indoor and Outdoor Air
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