Per- and polyfluoroalkyl substances (PFAS), often referred to as “forever chemicals” due to their persistence in the environment, have a fascinating history marked by accidental discoveries and significant industrial developments.
The perfect serendipity example
In 1938, Roy Plunkett, a young chemist working for DuPont, accidentally discovered polytetrafluoroethylene (PTFE) while searching for a new refrigerant. As they were working on a cylinder filled with tetrafluoroethylene (TFE) subjected to high pressure and very low temperature, Plunkett and his assistant, Jack Rebok, found a deposit of packed white powder on the bottom and lower sides of the cylinder. The gaseous TFE sample in the cylinder spontaneously polymerized into a waxy white solid. Plunkett would later recount the anecdote:
“On the morning of April 6, 1938, Jack Rebok, my assistant, selected one of the TFE cylinders that we had been using the previous day and set up the apparatus ready to go. When he opened the valve — to let the TFE gas flow under its own pressure from the cylinder — nothing happened…We were in a quandary. I couldn’t think of anything else to do under the circumstances, so we unscrewed the valve from the cylinder. By this time it was pretty clear that there wasn’t any gas left. I carefully tipped the cylinder upside down, and out came a whitish powder down onto the lab bench. We scraped around some with the wire inside the cylinder…to get some more of the powder. What I got out that way certainly didn’t add up, so I knew there must be more, inside. Finally…we decided to cut open the cylinder. When we did, we found more of the powder packed onto the bottom and lower sides of the cylinder.”
This material, later known as TeflonTM, was notable for its chemical resistance and non-stick properties, leading to a wide range of applications, including non-stick cookware.
The Emergence of PFOS and PFOA
Around the same time, 3M made a similar discovery in 1950 when they developed perfluorooctane sulfonate (PFOS) while looking for a rubber resistant to aviation fuels. This substance became notably used in Scotchgard, a fabric and carpet protection product launched in 1956.
In the early 1950s, DuPont also began using ammonium perfluorooctanoate (PFOA) in the production of Teflon. These two substances, PFOS and PFOA, became the most well-known PFAS, widely utilized in various industries, including firefighting foams used by the military and airports.
Controversies and Repercussions
Over time, the potential dangers of PFAS to human health and the environment became increasingly apparent. As early as the 1960s and 1970s, researchers found evidence of these substances accumulating in human and animal blood, as well as causing toxic effects on the liver and other organs.
In response to growing concerns, companies like 3M and DuPont began to phase out the use of certain PFAS. In 2000, 3M stopped producing PFOS, although other variants of PFAS continue to be used, presenting ongoing environmental challenges.
Conclusion
The history of PFAS is a classic example of an unexpected scientific discovery leading to widespread industrial applications, but also significant environmental and health controversies. Ongoing research continues to uncover the implications of these substances on our health and environment, while efforts are being made to mitigate their future impact.
Sources:
- Biography of Roy Plunkett, Wikipedia
- PFAS Chemicals: Origins & History, James F. Humphreys & Associates
- Timeline of events related to per- and polyfluoroalkyl substances, Wikipedia
- The history of PFAS: From World War II to your Teflon pan, Manufacturing Drive
- The History of Teflon™ Fluoropolymers, Teflon.com
*Image: Hagley Museum and Library